JP7618622B2 - Manufacturing method of developing device - Google Patents

Description

The present invention relates to a method for manufacturing a developing device equipped with a resin regulating blade.

The developing device is equipped with a regulating blade (developer regulating member) having a coat amount regulating surface (regulating portion) that regulates the amount of developer (developer coat amount) carried on the surface of the developer carrier that carries the developer to develop the electrostatic latent image formed on the image carrier. The regulating blade is arranged facing the developer carrier over the longitudinal direction of the developer carrier with a predetermined gap (hereinafter referred to as SB gap G) between it and the surface of the developer carrier. The SB gap G is the shortest distance between the surface of the developer carrier supported by the frame of the development container (developing frame) and the coat amount regulating surface of the regulating blade attached to the frame of the development container. By adjusting the size of this SB gap G, the amount of developer transported to the development area where the developer carrier faces the image carrier is adjusted.

The developing device described in Patent Document 1 includes a resin developer regulating member molded from resin, and a resin developing container frame molded from resin.

JP 2014-197175 A

As the width of the sheet on which the image is formed increases, the area of the coat amount control surface corresponding to the image area that can be formed on the image carrier increases, and the length of the longitudinal direction of the control blade increases. When a control blade with a large longitudinal length is molded from resin, it is difficult to guarantee the straightness of the coat amount control surface of the resin-made control blade molded from resin. This is because when a control blade with a large longitudinal length is molded from resin, the rate at which the thermally expanded resin thermally contracts tends to vary. Therefore, in a resin-made control blade, the SB gap G tends to vary in the longitudinal direction of the developer carrier due to the straightness of the coat amount control surface of the control blade as the longitudinal length of the control blade increases. If the SB gap G varies in the longitudinal direction of the developer carrier, there is a risk of unevenness in the amount of developer carried on the surface of the developer carrier in the longitudinal direction of the developer carrier.

Therefore, in a developing device equipped with a resin regulating blade, it is desirable to ensure that the SB gap G is within a predetermined range in the longitudinal direction of the developer carrier when the regulating blade is fixed to the mounting portion of the developing frame, regardless of the straightness of the coating amount regulating surface of the regulating blade.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for manufacturing a developing device in which the size of the gap between the developer carrier supported by the developing frame and the resin-made regulating blade attached to the attachment portion of the developing frame is within a predetermined range along the longitudinal direction of the developer carrier .

In order to achieve the above object, a method for manufacturing a developing device according to one aspect of the present invention has the following configuration: That is, a method for manufacturing a developing device including a developer carrier that carries and transports a developer to a development position, a resin regulating blade that is disposed opposite to the developer carrier in a non-contact manner and that regulates the amount of developer carried on the developer carrier, and a resin developing frame that has an attachment portion to which the regulating blade is attached and supports the developer carrier, the method comprising: a coating step of coating an adhesive on the attachment portion, and a positioning step of adjusting a force for bending the regulating blade so that the size of a gap between the developer carrier supported by the developing frame and the regulating blade attached to the attachment portion is within a predetermined tolerance range along the longitudinal direction of the developer carrier while applying the adjusted force to each of a plurality of locations in the longitudinal direction of the regulating blade, after the adhesive applied to the attachment portion in the coating step is brought into contact with the regulating blade and before the adhesive applied to the attachment portion in the coating step is completely cured, and determining a position for attaching the regulating blade to the attachment portion.
In order to achieve the above object, a manufacturing method of a developing device according to another aspect of the present invention has the following configuration: That is, a manufacturing method of a developing device including a developer carrier that carries and transports a developer to a development position, a resin regulating blade that is disposed opposite to the developer carrier in a non-contact manner and that regulates the amount of developer carried on the developer carrier, and a resin developing frame that has an attachment portion to which the regulating blade is attached and supports the developer carrier, the manufacturing method including a coating step of coating an adhesive on the regulating blade, and a positioning step of adjusting a force for bending the regulating blade and applying the adjusted force to each of a plurality of positions in the longitudinal direction of the regulating blade so that the size of a gap between the developer carrier supported by the developing frame and the regulating blade attached to the attachment portion is within a predetermined tolerance range along the longitudinal direction of the developer carrier, after the adhesive coated on the regulating blade is brought into contact with the attachment portion and before the adhesive coated on the regulating blade is completely hardened in the coating step, to determine a position for attaching the regulating blade to the attachment portion.

According to the present invention, the size of the gap between the developer carrier supported by the developing frame and the resin regulating blade attached to the mounting portion of the developing frame can be made to be within a predetermined range along the longitudinal direction of the developer carrier .

FIG. 1 is a cross-sectional view showing a configuration of an image forming apparatus. FIG. 2 is a perspective view illustrating a configuration of a developing device according to the first embodiment. FIG. 2 is a perspective view illustrating a configuration of a developing device according to the first embodiment. 1 is a cross-sectional view illustrating a configuration of a developing device according to a first embodiment. FIG. 2 is a perspective view showing a configuration of a resin developing frame (single unit); FIG. 2 is a perspective view showing a configuration of a resin doctor blade (single unit). FIG. 2 is a schematic diagram for explaining the rigidity of a resin doctor blade (single unit). 5A and 5B are schematic diagrams for explaining the rigidity of a resin developing frame (single unit); 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 1A to 1C are schematic diagrams for explaining steps of a method for fixing a resin doctor blade. 10 is a cross-sectional view for explaining deformation of a resin doctor blade caused by agent pressure. FIG. FIG. 2 is a perspective view illustrating deformation of a resin doctor blade caused by a temperature change. FIG. 11 is a perspective view showing a configuration of a developing device according to a second embodiment. FIG. 11 is a cross-sectional view showing a configuration of a developing device according to a second embodiment.

The following describes in detail the embodiments of the present invention with reference to the accompanying drawings. Note that the following embodiments do not limit the scope of the present invention, and not all of the combinations of features described in the first embodiment are necessarily essential to the solution of the present invention. The present invention can be implemented in a variety of applications, including printers, various printing machines, copiers, fax machines, and multifunction machines.

[First embodiment]
(Configuration of Image Forming Apparatus)
First, the configuration of an image forming apparatus according to a first embodiment of the present invention will be described with reference to the cross-sectional view of Fig. 1. As shown in Fig. 1, an image forming apparatus 60 includes an endless intermediate transfer belt (ITB) 61 as an intermediate transfer body, and four image forming units 600 arranged from the upstream side to the downstream side along the rotation direction (the direction of the arrow C in Fig. 1) of the intermediate transfer belt 61. Each of the image forming units 600 forms a toner image of each color, yellow (Y), magenta (M), cyan (C), and black (Bk).

The image forming unit 600 includes a rotatable photoconductor drum 1 as an image carrier. The image forming unit 600 also includes a charging roller 2 as a charging means, a developing device 3 as a developing means, a primary transfer roller 4 as a primary transfer means, and a photoconductor cleaner 5 as a photoconductor cleaning means, which are arranged along the rotation direction of the photoconductor drum 1.

Each of the developing devices 3 is detachably attached to the image forming device 60. Each of the developing devices 3 has a developing container 50 that contains a two-component developer (hereinafter simply referred to as developer) containing non-magnetic toner (hereinafter simply referred to as toner) and a magnetic carrier. In addition, each of the toner cartridges that contain toner of each color Y, M, C, and Bk is detachably attached to the image forming device 60. The toner of each color Y, M, C, and Bk is supplied to each of the developing containers 50 via a toner transport path. Details of the developing device 3 will be described later in Figures 2 to 4, and details of the developing container 50 will be described later in Figure 5.

The intermediate transfer belt 61 is tensioned by a tension roller 6, a driven roller 7a, a primary transfer roller 4, a driven roller 7b, and a secondary transfer inner roller 66, and is driven to be transported in the direction of arrow C in FIG. 1. The secondary transfer inner roller 66 also serves as a drive roller that drives the intermediate transfer belt 61. As the secondary transfer inner roller 66 rotates, the intermediate transfer belt 61 rotates in the direction of arrow C in FIG. 1.

The intermediate transfer belt 61 is pressed by the primary transfer roller 4 from the back side of the intermediate transfer belt 61. In addition, by bringing the intermediate transfer belt 61 into contact with the photosensitive drum 1, a primary transfer nip portion serving as a primary transfer portion is formed between the photosensitive drum 1 and the intermediate transfer belt 61.

An intermediate transfer body cleaner 8 as a belt cleaning means is in contact with the tension roller 6 across the intermediate transfer belt 61. In addition, a secondary transfer outer roller 67 as a secondary transfer means is disposed in a position facing the secondary transfer inner roller 66 across the intermediate transfer belt 61. The intermediate transfer belt 61 is sandwiched between the secondary transfer inner roller 66 and the secondary transfer outer roller 67. As a result, a secondary transfer nip portion as a secondary transfer portion is formed between the secondary transfer outer roller 67 and the intermediate transfer belt 61. In the secondary transfer nip portion, a predetermined pressure force and a transfer bias (electrostatic load bias) are applied to cause a toner image to adhere to the surface of the sheet S (e.g., paper, film, etc.).

The sheets S are stored in a stacked state in a sheet storage section 62 (e.g., a feeding cassette or a feeding deck, etc.). The feeding means 63 feeds the sheets S in accordance with the image formation timing, for example, using a friction separation method using a feeding roller or the like. The sheets S sent out by the feeding means 63 are transported to a registration roller 65 arranged midway along a transport path 64. After skew correction and timing correction are performed by the registration roller 65, the sheets S are transported to a secondary transfer nip section. In the secondary transfer nip section, the timing of the sheets S and the toner image coincides, and secondary transfer is performed.

A fixing device 9 is disposed downstream of the secondary transfer nip in the conveying direction of the sheet S. The fixing device 9 applies a predetermined pressure and heat to the sheet S conveyed to the fixing device 9, melting and fixing the toner image on the surface of the sheet S. The sheet S with the image fixed in this way is discharged directly to the discharge tray 601 by the forward rotation of the discharge rollers 69.

When performing double-sided image formation, the discharge rollers 69 are rotated in the forward direction to transport the sheet S until the rear end passes through the switching flapper 602, and then the discharge rollers 69 are rotated in the reverse direction. This switches the leading and trailing ends of the sheet S and transports it to the double-sided transport path 603. Then, in time for the next image formation, the sheet S is transported again to the transport path 64 by the re-feed rollers 604.

(Image Formation Process)
During image formation, the photoconductor drum 1 is rotated by a motor. The charging roller 2 uniformly charges the surface of the photoconductor drum 1 that is rotated in advance. The exposure device 68 forms an electrostatic latent image on the surface of the photoconductor drum 1 that has been charged by the charging roller 2, based on a signal of image information input to the image forming device 60. The photoconductor drum 1 is capable of forming electrostatic latent images of a plurality of sizes.

The developing device 3 has a rotatable developing sleeve 70 as a developer carrier that carries the developer. The developing device 3 uses the developer carried on the surface of the developing sleeve 70 to develop the electrostatic latent image formed on the surface of the photosensitive drum 1. As a result, toner adheres to the exposed area on the surface of the photosensitive drum 1, making it into a visible image. A transfer bias (electrostatic load bias) is applied to the primary transfer roller 4, and the toner image formed on the surface of the photosensitive drum 1 is transferred onto the intermediate transfer belt 61. The small amount of toner remaining on the surface of the photosensitive drum 1 after the primary transfer (transfer residual toner) is collected by the photosensitive cleaner 5 and prepared for the next image creation process.

The image forming process for each color, which is processed in parallel by the image forming unit 600 for each color of Y, M, C, and Bk, is performed at a timing that sequentially superimposes the toner image of the upstream color that has been primarily transferred onto the intermediate transfer belt 61. As a result, a full-color toner image is formed on the intermediate transfer belt 61, and the toner image is transported to the secondary transfer nip portion. A transfer bias is applied to the secondary transfer outer roller 67, and the toner image formed on the intermediate transfer belt 61 is transferred to the sheet S transported to the secondary transfer nip portion. The toner (transfer residual toner) remaining slightly on the intermediate transfer belt 61 after the sheet S passes through the secondary transfer nip portion is collected by the intermediate transfer body cleaner 8. The fixing device 9 fixes the toner image transferred onto the sheet S. The recording material S that has been subjected to the fixing process by the fixing device 9 is discharged to the discharge tray 601.

The series of image formation processes described above is now complete, and the machine is ready for the next image formation operation.

(Configuration of the developing device)
Next, the configuration of the developing device 3 according to the first embodiment of the present invention will be described with reference to the perspective view of Fig. 2, the perspective view of Fig. 3, and the cross-sectional view of Fig. 4. Fig. 4 is a cross-sectional view of the developing device 3 taken along the section H of Fig. 2.

The developing device 3 is provided with a developing container 50 which is made of a resin developing frame (hereinafter simply referred to as the developing frame 30) and a resin cover frame (hereinafter simply referred to as the cover frame 40) which is formed separately from the developing frame 30 and is also made of resin. Figures 2 and 4 show the state in which the cover frame 40 is attached to the developing frame 30, while Figure 3 shows the state in which the cover frame 40 is not attached to the developing frame 30. Details of the configuration of the developing frame 30 (single unit) will be described later in Figure 5.

The developing container 50 has an opening at a position corresponding to the developing area where the developing sleeve 70 faces the photosensitive drum 1. The developing sleeve 70 is rotatably disposed relative to the developing container 50 so that a portion of the developing sleeve 70 is exposed at the opening of the developing container 50. A bearing 71, which is a bearing member, is provided at each end of the developing sleeve 70.

The interior of the developing container 50 is partitioned by a partition 38 extending in the vertical direction into a developing chamber 31 as a first chamber and an agitating chamber 32 as a second chamber. The developing chamber 31 and the agitating chamber 32 are connected at both ends in the longitudinal direction via two communication sections 39 that the partition 38 has. Therefore, developer can communicate between the developing chamber 31 and the agitating chamber 32 via the communication sections 39. The developing chamber 31 and the agitating chamber 32 are arranged side by side in the horizontal direction.

A magnet roll is fixedly disposed inside the developing sleeve 70, which has multiple magnetic poles along the direction of rotation of the developing sleeve 70 and serves as a magnetic field generating means for generating a magnetic field for carrying developer on the surface of the developing sleeve 70. The developer in the developing chamber 31 is pumped up by the influence of the magnetic field caused by the magnetic poles of the magnet roll, and is supplied to the developing sleeve 70. Since the developer is supplied from the developing chamber 31 to the developing sleeve 70 in this manner, the developing chamber 31 is also referred to as a supply chamber.

In the developing chamber 31, a first transport screw 33 serving as a transport means for stirring and transporting the developer in the developing chamber 31 is disposed opposite the developing sleeve 70. The first transport screw 33 includes a rotating shaft 33a as a rotatable shaft portion, and a spiral blade portion 33b as a developer transport portion provided along the outer periphery of the rotating shaft 33a, and is rotatably supported by the developing container 50. Bearing members are provided on both ends of the rotating shaft 33a.

In addition, a second conveying screw 34 is disposed in the stirring chamber 32 as a conveying means for stirring the developer in the stirring chamber 32 and conveying it in the opposite direction to the first conveying screw 33. The second conveying screw 34 includes a rotating shaft 34a as a rotatable shaft portion and a spiral blade portion 34b as a developer conveying portion provided along the outer periphery of the rotating shaft 34a, and is rotatably supported by the developing container 50. Bearing members are provided on both ends of the rotating shaft 34a. The developer circulates between the developing chamber 31 and the stirring chamber 32 via the communication portion 39 as the first conveying screw 33 and the second conveying screw 34 are driven to rotate.

A regulating blade (hereinafter referred to as doctor blade 36) is attached to the developing container 50 as a developer regulating member that regulates the amount of developer carried on the surface of the developing sleeve 70 (also referred to as developer coat amount), facing the surface of the developing sleeve 70 without contacting it. The doctor blade 36 has a coat amount regulating surface 36r that serves as a regulating portion that regulates the amount of developer carried on the surface of the developing sleeve 70. The doctor blade 36 is a resin doctor blade molded from resin. The configuration of the doctor blade 36 (single unit) will be described later with reference to FIG. 6.

The doctor blade 36 is disposed opposite the developing sleeve 70 with a predetermined gap (hereinafter referred to as SB gap G) between the developing sleeve 70 and the developing sleeve 70 across the longitudinal direction of the developing sleeve 70 (i.e., the direction parallel to the rotation axis direction of the developing sleeve 70). In the present invention, the SB gap G is the shortest distance between the area of the developing sleeve 70 that corresponds to the maximum image area that can be formed on the surface of the photosensitive drum 1 (so-called the maximum image area of the developing sleeve 70) and the area of the doctor blade 36 that corresponds to the maximum image area (so-called the maximum image area of the doctor blade 36). In the first embodiment, since the photosensitive drum 1 can form electrostatic latent images of multiple sizes, the maximum image area refers to the image area that corresponds to the largest size (e.g., A3 size) of the multiple sizes of image areas that can be formed on the photosensitive drum 1. On the other hand, in a modified example in which the photosensitive drum 1 can form electrostatic latent images of only one size, the maximum image area is interpreted as referring to the image area of that one size that can be formed on the photosensitive drum 1.

The doctor blade 36 is disposed substantially opposite the peak position of the magnetic flux density of the magnetic pole of the magnet roll. The developer supplied to the developing sleeve 70 is affected by the magnetic field of the magnetic pole of the magnet roll. In addition, the developer regulated and scraped off by the doctor blade 36 tends to accumulate in the upstream portion of the SB gap G. As a result, a developer pool is formed upstream of the doctor blade 36 in the rotation direction of the developing sleeve 70. Then, a part of the developer in the developer pool is transported so as to pass through the SB gap G as the developing sleeve 70 rotates. At this time, the layer thickness of the developer passing through the SB gap G is regulated by the coat amount regulating surface 36r of the doctor blade 36. In this way, a thin layer of developer is formed on the surface of the developing sleeve 70.

Then, a predetermined amount of developer carried on the surface of the developing sleeve 70 is transported to the developing area as the developing sleeve 70 rotates. Therefore, the amount of developer transported to the developing area is adjusted by adjusting the size of the SB gap G. In the first embodiment, the size of the SB gap G that is targeted when adjusting the size of the SB gap G (the so-called target value of the SB gap G) is set to approximately 300 μm.

The developer transported to the development area forms magnetic spikes by standing in the development area. When these magnetic spikes come into contact with the photosensitive drum 1, the toner in the developer is supplied to the photosensitive drum 1. The electrostatic latent image formed on the surface of the photosensitive drum 1 is then developed into a toner image. The developer on the surface of the development sleeve 70 after passing through the development area and supplying the toner to the photosensitive drum 1 (hereinafter referred to as the developer after the development process) is peeled off from the surface of the development sleeve 70 by the repulsive magnetic field formed between the magnetic poles of the magnet roll with the same polarity. The developer after the development process that has been peeled off from the surface of the development sleeve 70 falls into the development chamber 31 and is collected there.

As shown in FIG. 4, the developer container 50 is provided with a developer guide portion 35 for guiding the developer to be transported toward the SB gap G. The developer guide portion 35 and the developing frame 30 are integrally formed, and the developer guide portion 35 and the doctor blade 36 are separately formed. The developer guide portion 35 is formed inside the developing frame 30 and is disposed upstream of the coat amount control surface 36r of the doctor blade 36 in the rotation direction of the developing sleeve 70. The developer guide portion 35 stabilizes the flow of the developer and adjusts it to a predetermined developer density, thereby defining the weight of the developer at the position where the coat amount control surface 36r of the doctor blade 36 is closest to the surface of the developing sleeve 70.

As shown in FIG. 4, the cover frame 40 is formed separately from the developing frame 30 and attached to the developing frame 30. The cover frame 40 covers a part of the opening of the developing frame 30 so that a part of the outer peripheral surface of the developing sleeve 70 is covered over the entire longitudinal area of the developing sleeve 70. At this time, the cover frame 40 covers a part of the opening of the developing frame 30 so that the developing area of the developing sleeve 70 facing the photosensitive drum 1 is exposed. In the first embodiment, the cover frame 40 is fixed to the developing frame 30 by ultrasonic bonding, but the method of fixing the cover frame 40 to the developing frame 30 may be any method such as screw fastening, snap fitting, bonding, welding, etc.

Next, the configuration of the developing frame 30 (single unit) will be described using the perspective view of Figure 5. Figure 5 shows the developing frame 30 in a state where the cover frame 40 is not attached.

The developing frame 30 has a developing chamber 31 and an agitating chamber 32 that is partitioned from the developing chamber 31 by a partition wall 38. The partition wall 38 is molded from resin and may be formed separately from the developing frame 30 or may be formed integrally with the developing frame 30.

The developing frame 30 has a sleeve support portion 42 for supporting the developing sleeve 70 rotatably by supporting bearings 71 provided at both ends of the developing sleeve 70. The developing frame 30 also has a blade attachment portion 41 formed integrally with the sleeve support portion 42 for attaching the doctor blade 36. Figure 5 shows a hypothetical state in which the doctor blade 36 is raised above the blade attachment portion 41.

In the first embodiment, with the doctor blade 36 attached to the blade attachment portion 41, adhesive A applied to the blade attachment surface 41s of the blade attachment portion 41 hardens, thereby fixing the doctor blade 36 to the blade attachment portion 41. Details of the method of fixing the doctor blade 36 to the blade attachment portion 41 will be described later from FIG. 9 onwards.

(Plastic doctor blade)
As the width of the sheet S on which an image is to be formed increases, for example to A3 size, the area of the coat amount control surface corresponding to the maximum image area that can be formed on the surface of the photosensitive drum 1 increases, and therefore the longitudinal length of the doctor blade increases.

When a doctor blade with a large longitudinal length is molded from resin, it is difficult to guarantee the straightness of the coating amount control surface of the resin doctor blade molded from resin. This is because when a doctor blade with a large longitudinal length is molded from resin, the rate at which the thermally expanded resin thermally contracts is likely to vary. The straightness of the coating amount control surface is expressed as the absolute value of the difference between the maximum and minimum values of the outer shape of the coating amount control surface when a specified point on the coating amount control surface in the longitudinal direction of the coating amount control surface is used as a reference. For example, the center of the coating amount control surface in the longitudinal direction of the coating amount control surface is set as the origin of a Cartesian coordinate system, a specified straight line passing through the origin is set as the X-axis, and a straight line drawn from the origin at a right angle to the X-axis is set as the Y-axis. In this Cartesian coordinate system, the straightness of the coating amount control surface is expressed as the absolute value of the difference between the maximum and minimum values of the Y-coordinate of the outer shape of the coating amount control surface.

For example, if a resin doctor blade whose longitudinal length corresponds to A3 size (hereafter referred to as an A3 size resin doctor blade) is manufactured with the precision of a typical resin molded product, the straightness of the coat amount control surface is approximately 300 μm to 500 μm. Even if an A3 size resin doctor blade is manufactured with high precision using a high precision resin material, the straightness of the coat amount control surface is approximately 100 μm to 200 μm.

Therefore, in the case of a resin doctor blade, the SB gap tends to vary in the longitudinal direction of the developer carrier due to the straightness of the coating amount control surface as the longitudinal length of the doctor blade increases. If the SB gap varies in the longitudinal direction of the developer carrier, there is a risk of unevenness occurring in the amount of developer carried on the surface of the developer carrier in the longitudinal direction of the developer carrier.

Therefore, in the first embodiment, in order to suppress unevenness in the amount of developer carried on the surface of the developing sleeve 70 in the longitudinal direction of the developing sleeve 70, the SB gap G is set to be within a predetermined range along the longitudinal direction of the developing sleeve 70. Specifically, in the first embodiment, the tolerance of the SB gap G (i.e., the tolerance of the SB gap G relative to the target value) is set to ±10% or less, and the SB gap G is set to be within a predetermined range along the longitudinal direction of the developing sleeve 70.

In the first embodiment, the method described below is used to determine whether the SB gap G is within a predetermined range in the longitudinal direction of the developing sleeve 70. Details of the measurement method (calculation method) of the SB gap G will be described later with reference to FIG. 11.

First, the area corresponding to the maximum image area of the doctor blade 36 is divided into four or more equal parts, and the SB gap G is measured at five or more points at each divided part of the doctor blade 36 (including both ends and the center of the area corresponding to the maximum image area of the doctor blade 36). Then, from the sample of measurement values of the SB gap G measured at five or more points, the maximum value of the SB gap G, the minimum value of the SB gap G, and the median value of the SB gap G are extracted. At this time, it is sufficient that the absolute value of the difference between the maximum value of the SB gap G and the median value of the SB gap G is 10% or less of the median value of the SB gap G, and the absolute value of the difference between the minimum value of the SB gap G and the median value of the SB gap G is 10% or less of the median value of the SB gap G. In this case, it is satisfied that the tolerance of the SB gap G is ±10% or less, and that the SB gap G is within a predetermined range over the longitudinal direction of the developing sleeve 70.

For example, if the median value of SB gap G is 300 μm from a sample of SB gap G measurements taken at five or more locations, the maximum value of SB gap G should be 330 μm or less, and the minimum value of SB gap G should be 270 μm or more. In other words, in this case, the adjustment value of SB gap G is 300 μm ± 30 μm, which means that the tolerance of SB gap G is allowed up to 60 μm. For this reason, even if an A3-size resin doctor blade is manufactured with the precision of a typical resin molded product, or even if it is manufactured with high precision using a high-precision resin material, the straightness accuracy of the coat amount control surface alone will exceed the allowable range for the tolerance of SB gap G.

Therefore, in a developing device equipped with a plastic doctor blade, it is desirable to ensure that the SB gap G is within a predetermined range in the longitudinal direction of the developer carrier when the doctor blade is fixed to the mounting portion of the developing frame, regardless of the straightness of the coating amount control surface. In the first embodiment, by adopting the configuration described below, even if a plastic doctor blade with low accuracy of straightness of the coating amount control surface is used, when the doctor blade is fixed to the mounting portion of the developing frame, the gap between the developer carrier and the doctor blade is within a predetermined range in the longitudinal direction of the developer carrier. Details are explained below.

First, the configuration of the doctor blade 36 (single unit) will be explained using the perspective view of Figure 6.

During the image forming operation (developing operation), developer pressure (hereinafter referred to as developer pressure) generated by the flow of developer is applied to the doctor blade 36. The smaller the rigidity of the doctor blade 36, the more likely it is that the doctor blade 36 will deform and the more likely the size of the SB gap G will fluctuate when developer pressure is applied to the doctor blade 36 during the image forming operation (developing operation). During the image forming operation (developing operation), the developer pressure is applied in the short-side direction of the doctor blade 36 (the direction of the arrow M in FIG. 6). Therefore, in order to suppress fluctuations in the size of the SB gap G during the image forming operation (developing operation), it is desirable to make the doctor blade 36 more resistant to deformation in the short-side direction by increasing the rigidity of the doctor blade 36 in the short-side direction.

6, in the first embodiment, the doctor blade 36 is plate-shaped from the viewpoint of mass production and cost. Also, as shown in FIG. 6, in the first embodiment, the cross-sectional area of the side surface 36t of the doctor blade 36 is made small, and further, the length t2 in the thickness direction of the doctor blade 36 is made smaller than the length t1 in the short direction of the doctor blade 36. As a result, the doctor blade 36 (single unit) is easily deformed in the direction perpendicular to the longitudinal direction of the doctor blade 36 (the direction of the arrow N in FIG. 6) (the direction of the arrow M in FIG. 6). Therefore, in the first embodiment, in order to correct the straightness of the coat amount control surface 36r, the doctor blade 36 is fixed to the blade mounting portion 41 of the developing frame 30 with at least a part of the doctor blade 36 bent in the direction of the arrow M in FIG. 6. The details of the method of fixing the doctor blade 36 to the blade mounting portion 41 of the developing frame 30 (hereinafter referred to as the fixing method of the doctor blade 36) will be described later in FIG. 9 and subsequent figures.

Next, the rigidity of the doctor blade 36 (single unit) will be explained using the schematic diagram in FIG. 7. The rigidity of the doctor blade 36 (single unit) is measured when the doctor blade 36 is not fixed to the blade attachment portion 41 of the developing frame 30.

As shown in FIG. 7, a concentrated load F1 is applied in the short-side direction of the doctor blade 36 to the central portion 36z of the doctor blade 36 in the longitudinal direction of the doctor blade 36. At this time, the rigidity of the doctor blade 36 (single unit) is measured based on the amount of deflection in the short-side direction of the doctor blade 36 at the central portion 36z of the doctor blade 36.

For example, assume that a concentrated load F1 of 300 gf is applied in the short direction of the doctor blade 36 to the central portion 36z of the doctor blade 36 in the longitudinal direction of the doctor blade 36. At this time, the deflection amount in the short direction of the doctor blade 36 at the central portion 36z of the doctor blade 36 is 700 μm or more. At this time, the deformation amount of the central portion 36z of the doctor blade 36 on the cross section is 5 μm or less.

Next, the rigidity of the developing frame 30 (single unit) will be described using the schematic diagram in FIG. 8. The rigidity of the developing frame 30 (single unit) is measured when the doctor blade 36 is not fixed to the blade attachment portion 41 of the developing frame 30.

As shown in FIG. 8, a concentrated load F1 is applied in the short-side direction of the blade mounting portion 41 to the central portion 41z of the blade mounting portion 41 in the longitudinal direction of the blade mounting portion 41. At this time, the rigidity of the developing frame 30 (alone) is measured based on the amount of deflection in the short-side direction of the blade mounting portion 41 at the central portion 41z of the blade mounting portion 41.

For example, assume that a concentrated load F1 of 300 gf is applied in the short direction of the blade mounting portion 41 to the central portion 41z of the blade mounting portion 41 in the longitudinal direction of the blade mounting portion 41. At this time, the amount of deflection in the short direction of the blade mounting portion 41 at the central portion 41z of the blade mounting portion 41 is 60 μm or less.

Let us assume that a concentrated load F1 of the same magnitude is applied to the center 36z of the doctor blade 36 and the center 41z of the blade mounting portion 41 of the developing frame 30. At this time, the amount of bending of the center 36z of the doctor blade 36 is more than 10 times the amount of bending of the center 41z of the blade mounting portion 41. Therefore, the rigidity of the developing frame 30 (single unit) is more than 10 times greater than the rigidity of the doctor blade 36 (single unit). Therefore, when the doctor blade 36 is attached to the blade mounting portion 41 of the developing frame 30 and the doctor blade 36 is fixed to the blade mounting portion 41 of the developing frame 30, the rigidity of the developing frame 30 becomes dominant over the rigidity of the doctor blade 36.

The rigidity of the developing frame 30 (alone) is greater than the rigidity of the cover frame 40 (alone). Therefore, when the cover frame 40 is attached to the developing frame 30 and fixed to the developing frame 30, the rigidity of the developing frame 30 becomes dominant over the rigidity of the cover frame 40.

(How to fix a plastic doctor blade)
9 to 14, the steps of the method for fixing the doctor blade 36 will be described. An external device (hereinafter, simply referred to as device 100) performs the steps of the method for fixing the doctor blade 36 described below.

First, the device 100 detects the outer shape of the coat amount control surface 36r of the doctor blade 36. Next, the device 100 recognizes the straightness of the coat amount control surface 36r with respect to the outer shape of the coat amount control surface 36r in the longitudinal direction of the coat amount control surface 36r, based on the center of the coat amount control surface 36r (the tip 36e3 of the doctor blade 36). In the process of the fixing method of the doctor blade 36, a resin doctor blade corresponding to A3 size manufactured with the accuracy of a general resin molded product is used. Therefore, the device 100 recognizes that the straightness of the coat amount control surface 36r is about 300 μm to 500 μm. Then, the device 100 deflects at least a part of the area corresponding to the maximum image area of the doctor blade 36 by the force applied to the doctor blade 36. Then, the device 100 corrects the straightness of the coat amount control surface 36r to 50 μm or less (hereinafter referred to as the deflection process).

Next, the device 100 determines the position at which to fix the doctor blade 36, at least a portion of which has been deflected in the deflection process, to the blade attachment portion 41 of the developing frame 30 in order to set the SB gap G within a predetermined range (hereinafter referred to as the positioning process). Next, with the doctor blade 36 in a state in which the portion of the area corresponding to the maximum image area is deflected, the device 100 fixes the portion of the area corresponding to the maximum image area of the doctor blade 36 at the predetermined position of the blade attachment portion 41 determined in the positioning process (hereinafter referred to as the fixing process).

The device 100 has a stand 103 on which the doctor blade 36 (single unit) is placed. The device 100 also has five fingers 101 (101p1 to 101p5) for gripping each of the gripping portions 37 (37p1 to 37p5) provided at five locations within an area corresponding to the maximum image area of the doctor blade 36. Each of the fingers 101 (101p1 to 101p5) can independently move in the J direction in FIG. 9, and can move forward and backward in the J direction in FIG. 9.

The device 100 also has five cameras 102 (102p1-102p5) for measuring the positions of the five tips 36e (36e1-36e5) included in the coat amount control surface 36r of the doctor blade 36. The cameras 102 (102p1-102p5) are arranged along the direction toward the tips 36e (36e1-36e5) of the doctor blade 36 (the direction of arrow F in FIG. 9). The cameras 102 (102p1-102p5) measure the positions of the tips 36e (36e1-36e5) of the doctor blade 36, thereby detecting the outline of the coat amount control surface 36r of the doctor blade 36. Next, the device 100 recognizes the straightness of the coat amount control surface 36r with respect to the outer shape of the coat amount control surface 36r in the longitudinal direction of the coat amount control surface 36r, using the center of the coat amount control surface 36r (tip 36e3 of the doctor blade 36) as a reference. Note that, although an example in which the position of the tip 36e (36e1 to 36e5) of the doctor blade 36 is measured using the camera 102 (102p1 to 102p5) will be described below, a modified example in which this is done using a non-contact sensor may also be used.

The doctor blade 36 is manufactured with the precision of a typical resin molded product. As mentioned above, when a resin doctor blade for A3 size is manufactured with the precision of a typical resin molded product, the straightness of the coating amount control surface is about 300 μm to 500 μm. Assume that the doctor blade 36 is a resin doctor blade for A3 size manufactured with the precision of a typical resin molded product. In this case, when the doctor blade 36 is placed on the mounting table 103, the positions of the five tips 36e (36e1 to 36e5) of the doctor blade 36 are measured with the camera 102 (102p1 to 102p5), and there is a difference of about 300 μm to 500 μm. On the other hand, as mentioned above, in order to suppress unevenness in the amount of developer carried on the surface of the developing sleeve 70 in the longitudinal direction of the developing sleeve 70, the tolerance of the SB gap G is set to ±10% or less.

Therefore, taking into consideration the allowable tolerance of the SB gap G and the mounting accuracy of the doctor blade 36 relative to the developing frame 30, it is necessary to correct the straightness of the tip portions 36e1-36e5 of the doctor blade 36 (i.e., the straightness of the coat amount control surface 36r) to 50 μm or less. Furthermore, considering that the straightness accuracy of a metal doctor blade is 20 μm or less due to secondary cutting, it is more preferable to correct the straightness of the coat amount control surface 36r of the resin doctor blade 36 to 20 μm or less.

Next, we will explain in detail the series of steps in the method for fixing the doctor blade 36 (deflection step, positioning step, and fixing step).

(1) Deflection Process First, the details of the deflection process will be described with reference to the schematic diagram of Fig. 9. The device 100 holds the doctor blade 36 by gripping the gripping portion 37 (37p1 to 37p5) of the doctor blade 36 with the fingers 101 (101p1 to 101p5). Next, the camera 102 (102p1 to 102p5) measures the position of the tip 36e (36e1 to 36e5) of the doctor blade 36 while the gripping portion 37 (37p1 to 37p5) of the doctor blade 36 is gripped with the fingers 101 (101p1 to 101p5). In this way, the device 100 detects the outline of the coat amount control surface 36r of the doctor blade 36. Next, the device 100 recognizes the straightness of the coat amount control surface 36r with respect to the outer shape of the coat amount control surface 36r in the longitudinal direction of the coat amount control surface 36r, using the center of the coat amount control surface 36r (the tip 36e3 of the doctor blade 36) as a reference.

Then, the device 100, with the gripping portions 37 (37p1 to 37p5) of the doctor blade 36 gripped by the fingers 101 (101p1 to 101p5), moves each of the fingers 101 in the direction J in FIG. 9. As a result, the device 100 applies a force to the doctor blade 36 via the gripping portions 37 of the doctor blade 36 gripped by the fingers 101 to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36. Therefore, the gripping portions 37 of the doctor blade 36 serve as a force receiving portion for receiving the force applied from the device 100 to the doctor blade 36 to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36.

As shown in FIG. 10, the doctor blade 36 (single unit) has a shape in which the center of the coat amount control surface 36r of the doctor blade 36 is largely bent in the longitudinal direction of the doctor blade 36. Therefore, it is necessary to correct the straightness of the coat amount control surface 36r of the doctor blade 36 by reducing the difference in the position of the tip 36e (36e1 to 36e5) of the doctor blade 36. Therefore, based on the result of measuring the position of the tip 36e (36e1 to 36e5) of the doctor blade 36 (the detected outer shape of the coat amount control surface 36r), the difference in the position of the tip 36e (36e1 to 36e5) of the doctor blade 36 is reduced. To this end, the device 100 applies a force (also called a straightness correction force) to the doctor blade 36 for bending at least a part of the area corresponding to the maximum image area of the doctor blade 36, thereby correcting the straightness of the coat amount control surface 36r to 50 μm or less.

Then, the device 100 grips the gripping portion 37 (37p1 to 37p5) of the doctor blade 36 placed on the stand 103 with the fingers 101 (101p1 to 101p5). Then, while the device 100 grips the gripping portion 37 (37p1 to 37p5) of the doctor blade 36 with the fingers 101 (101p1 to 101p5), it moves each of the fingers 101 forward or backward independently in the direction of the arrow J in FIG. 9. At this time, the device 100 applies a force to the doctor blade 36 via the gripping portion 37 of the doctor blade 36 to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36.

In the example of Fig. 10, the device 100 applies a straightness correction force to the doctor blade 36 so that the outer shapes of the tips 36e1 and 36e5 of the doctor blade 36 are aligned with the reference, based on the outer shapes of the tips 36e2, 36e3, and 36e4. In the example of Fig. 10, the doctor blade 36 receives a force from the outside via three of the five gripping portions 37 (37p2 to 37p4) to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36. Then, due to the force received by the doctor blade 36 via the three gripping portions 37 (37p2 to 37p4), a straightness correction force is applied in the direction of arrow I in Fig. 10 to the tips 36e2 to 36e4 of the doctor blade 36 to correct the straightness of the coat amount control surface 36r. At this time, a straightness correction force is applied to the coat amount control surface 36r, and at least a portion of the area corresponding to the maximum image area of the doctor blade 36 is bent, thereby correcting the straightness of the coat amount control surface 36r of the doctor blade 36. In the example of FIG. 10, the shape of the coat amount control surface 36r of the doctor blade 36 is corrected from the coat amount control surface 36r1 to the coat amount control surface 36r2.

As a result, the straightness of the coat amount control surface 36r of the doctor blade 36 can be corrected to 50 μm or less. In the example of FIG. 10, the reference when the device 100 adjusts the outer shape of the tip 36e of the doctor blade 36 is the outer shape of the tips 36e1 and 36e5 of the doctor blade 36, but in a modified example, the reference may be the tip 36e3 (i.e., the center of the coat amount control surface 36r). In this modified example, the device 100 applies a straightness correction force to the doctor blade 36 so that the outer shape of the tip 36e3 of the doctor blade 36 is adjusted to the reference.

In the first embodiment, in consideration of a realistic mass production process, the straightness correction setting value of the coat amount control surface 36r of the doctor blade 36 is set to about 20 μm to 50 μm, and the magnitude of the straightness correction force applied to the tip 36e of the doctor blade 36 is set to about 500 g. In general, the smaller the magnitude of the straightness correction force applied to the tip 36e of the doctor blade 36, the cheaper and more compact the device 100 can be. However, if the magnitude of the straightness correction force applied to the tip 36e of the doctor blade 36 is too small compared to the rigidity of the doctor blade 36, it becomes impossible to correct the straightness of the coat amount control surface 36r of the doctor blade 36. Therefore, the magnitude of the straightness correction force applied to the tip 36e of the doctor blade 36 is set based on the rigidity of the doctor blade 36.

9, an example in which the gripping portion 37 is provided at five locations on the doctor blade 36 has been described, but as long as the straightness correction force can be applied to the coat amount control surface 36r, the locations and number of gripping portions 37 provided on the doctor blade 36 are not limited to this. In addition, in the example of FIG. 9, an example in which the gripping portion 37 of the doctor blade 36 has a convex shape has been described, but the shape of the gripping portion 37 is not limited to this. As described above, the finger 101 grips the gripping portion 37 of the doctor blade 36 so that the device 100 applies a force (straightness correction force) to the doctor blade 36 to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36. Therefore, as long as the finger 101 can grip the gripping portion 37, the shape of the gripping portion 37 may be, in addition to a convex shape, a concave shape, a groove shape, a notch shape, or a flat shape, or may be a combination of these shapes. In addition, in the drawings in this specification in which the doctor blade 36 is shown, except for Figures 9 to 12, the gripping portion 37 of the doctor blade 36 is omitted.

(2) Positioning Process Next, the positioning process will be described in detail with reference to the schematic views of Fig. 11 and Fig. 12. As shown in Fig. 11 and Fig. 12, the positioning process is performed in a state where the developing sleeve 70 is supported by the sleeve supporting portion 42 of the developing frame 30.

The fingers 101 (101p1 to 101p5) hold the doctor blade 36 in the state in which it has been bent in the bending process (i.e., the state in which the straightness of the coating amount control surface 36r has been corrected), and move the doctor blade 36 from the stand 103 to the blade attachment part 41. The amount and direction of movement of the fingers 101 (101p1 to 101p5) are preset in a program. The fingers 101 (101p1 to 101p5) are driven by an actuator and operate according to a preset program.

Then, the device 100 moves the doctor blade 36 in the bent state to the blade attachment portion 41 of the developing frame 30 while the fingers 101 (101p1 to 101p5) are still gripping the gripping portion 37 of the doctor blade 36 in the bending process. Next, the device 100 attaches the doctor blade 36 in the bent state to the blade attachment portion 41. At this time, the doctor blade 36 in the bent state is in a state where it lands on (also called a hit state) the blade attachment surface 41s of the developing frame 30 (see Figures 4 and 5).

Figure 11 shows the doctor blade 36 in a state where it has been bent in the bending process and the gripping portion 37 (37p1 to 37p5) of the doctor blade 36 is gripped by the fingers 101 (101p1 to 101p5) while the doctor blade 36 is landed on the blade attachment surface 41s.

As described above, in order to suppress unevenness in the amount of developer carried on the surface of the developing sleeve 70 in the longitudinal direction of the developing sleeve 70, the tolerance range of the SB gap G (i.e., the range allowed as a tolerance for the target value of the SB gap G) is set to a range of about 60 μm. Since the tolerance range of the SB gap G is strict, simply landing the doctor blade 36 on the blade mounting surface 41s of the developing frame 30 is unlikely to cause the SB gap G to fall within the adjustment range of the SB gap G that takes into account the tolerance range of the SB gap G (i.e., the adjustment range of the SB gap G includes the target value of the SB gap G). Therefore, it is necessary to adjust the SB gap G so that it falls within the adjustment range of the SB gap G by determining the position at which the doctor blade 36 is fixed relative to the blade mounting surface 41s of the developing frame 30 so that the SB gap G falls within the tolerance range.

The device 100 has five cameras 104 (104p1 to 104p5) for measuring the positions of the five tips 36e (36e1 to 36e5) of the doctor blade 36 when it is landed on the blade mounting surface 41s of the developing frame 30 by the finger 101. The cameras 104 (104p1 to 104p5) are arranged in a direction toward the tips 36e (36e1 to 36e5) of the doctor blade 36 (the direction of the arrow F in FIG. 11), and can measure the positions of the tips 36e (36e1 to 36e5) of the doctor blade 36. In the first embodiment, an example in which the positions of the tips 36e (36e1 to 36e5) of the doctor blade 36 are measured by the cameras 104 (104p1 to 104p5) will be described below, but a modified example in which the positions of the tips 36e (36e1 to 36e5) of the doctor blade 36 are measured by a non-contact sensor may be used.

Here, a method for measuring (calculating) the size of the SB gap G will be described. The size of the SB gap G is measured with the developing sleeve 70 supported by the sleeve support portion 42 of the developing frame 30, the doctor blade 36 attached to the blade attachment portion 41 of the developing frame 30, and the cover frame 40 fixed to the developing frame 30. In measuring the size of the SB gap G, a light source (e.g., an LED array or a light guide) is inserted into the developing chamber 31 along the longitudinal direction of the developing chamber 31. The light source inserted into the developing chamber 31 irradiates light from within the developing chamber 31 toward the SB gap G. The camera 104 (104p1 to 104p5) then captures the light emitted from the SB gap G to the outside of the developing frame 30. At this time, the camera 104 (104p1 to 104p5) reads the position 70a (70a1 to 70a5) on the surface of the developing sleeve 70 where the developing sleeve 70 is closest to the doctor blade 36, and the tip 36e (36e1 to 36e5) of the doctor blade 36. Next, the device 100 converts the pixel values from the image data generated by reading with the camera 104 (104p1 to 104p5) into distances, and calculates the size of the SB gap G. If the calculated size of the SB gap G is not within a predetermined range, the device 100 adjusts the SB gap G.

Here, the details of the method for adjusting the SB gap G will be described with reference to the schematic diagram of FIG. 12. The device 100 grips the gripping portion 37 (37p1-37p5) of the doctor blade 36 with the finger 101 (101p1-101p5), and moves the finger 101 in the direction of the arrow K shown in FIG. 12. The direction of the arrow K in FIG. 12 is the direction in which the relative position of the doctor blade 36 with respect to the developing sleeve 70 supported by the sleeve support portion 42 of the developing frame 30 is adjusted (i.e., the direction that defines the SB gap G). The direction of the arrow K in FIG. 12 also indicates the direction in which the doctor blade 36 approaches or moves away from the developing sleeve 70 supported by the sleeve support portion 42 of the developing frame 30. This adjusts the relative position of the tip 36e (36e1-36e5) of the doctor blade 36 to the position 70a (70a1-70a5) on the surface of the developing sleeve 70 where the developing sleeve 70 is closest to the doctor blade 36.

For example, assume that the SB gap G calculated at the initial position where the doctor blade 36 lands on the blade mounting surface 41s of the developing frame 30 is 350 μm. On the other hand, assume that the adjustment range of the SB gap G is 300 μm ± 30 μm, and the tolerance of the SB gap G is allowed up to 60 μm. In this case, at the initial position where the doctor blade 36 lands on the blade mounting surface 41s of the developing frame 30, the SB gap G is 50 μm larger than the nominal value of 300 μm. Therefore, while gripping the gripping portion 37 of the doctor blade 36, the finger 101 translates the doctor blade 36 in the direction of the arrow K shown in FIG. 12, in a direction that brings the doctor blade 36 50 μm closer to the surface of the developing sleeve 70.

Then, the camera 104 reads the position 70a (70a1 to 70a5) closest to the doctor blade 36 translated by the finger 101, and the tip 36e (36e1 to 36e5) of the doctor blade 36 translated by the finger 101. Next, the device 100 recalculates the SB gap G for the doctor blade 36 translated by the finger 101.

When the device 100 determines that the calculated size of the SB gap G is within the range of the SB gap G adjustment value (300 μm ± 30 μm), it ends the above-mentioned adjustment of the SB gap G. On the other hand, when the device 100 determines that the calculated size of the SB gap G is not within the SB gap G adjustment range (300 μm ± 30 μm), it repeats the above-mentioned adjustment of the SB gap G until it is within the SB gap G adjustment range (300 μm ± 30 μm). In this way, by fixing the doctor blade 36 to the blade attachment portion 41 of the developing frame 30 with the straightness of the coat amount control surface 36r corrected to 50 μm or less, the size of the SB gap G can be brought into the SB gap G adjustment range.

Here, a more preferred embodiment for adjusting the SB gap G with higher precision will be described with reference to the schematic diagrams of Figures 13 and 14. In this embodiment, the SB gap G is adjusted with higher precision by considering not only the straightness of the coat amount control surface 36r of the doctor blade 36 but also the straightness of the surface of the developing sleeve 70.

The sleeve tube that constitutes the outer shell of the developing sleeve 70 is made of metal, so by subjecting the sleeve tube to secondary cutting processing, the straightness of the surface of the developing sleeve 70 can be made highly accurate, such as ±15 μm or less. However, the straightness of ±15 μm that the developing sleeve 70 has means that when the developing sleeve 70 is rotating in actual use, the outer diameter of the developing sleeve 70 appears to vary by ±15 μm. In order to minimize the effect on the SB gap G caused by the accuracy of the straightness of the coat amount control surface 36r of the doctor blade 36 when the developing sleeve 70 is rotating, it is effective to measure the SB gap G while rotating the developing sleeve 70.

Figure 13 shows the position of the tip 36e of the doctor blade 36 when the developing sleeve 70 is stopped. Figure 13(A) shows the state in which the SB gap G has been adjusted with the developing sleeve 70 stopped at a position far from the doctor blade 36. Meanwhile, Figure 13(B) shows the state in which the SB gap G has been adjusted with the developing sleeve 70 stopped at a position close to the doctor blade 36. Also, Figure 14 shows the position of the tip 36e of the doctor blade 36 when the developing sleeve 70 is rotating.

As shown in Figs. 13A and 13B, the size of the SB gap G is the same between Figs. 13A and 13B, but the position of the tip 36e of the doctor blade 36 is different between Figs. 13A and 13B. In addition, there is a difference between the phase of the developing sleeve 70 when the developing sleeve 70 is stopped at a position far from the doctor blade 36 and the phase of the developing sleeve 70 when the developing sleeve 70 is stopped at a position close to the doctor blade 36. As a result, even if the developing sleeve 70 and the doctor blade 36 with the same accuracy are used and adjusted with the same SB gap G adjustment value, the doctor blade 36 will be fixed to the blade attachment portion 41 of the developing frame 30 with the tip 36e in a different position. This means that manufacturing variations will be allowed in the manufacturing of the developing device 3. Therefore, the SB gap G is adjusted while rotating the developing sleeve 70, thereby reducing manufacturing variations.

When the developing sleeve 70 is rotated, the straightness of the surface of the developing sleeve 70 causes a vibration of the outer diameter line of the developing sleeve 70 (hereinafter referred to as the vibration of the outer diameter of the developing sleeve 70). As shown in FIG. 14, the outer diameter line of the developing sleeve 70 is seen to move back and forth between the outer diameter line 73L1 of the developing sleeve 70 and the outer diameter line 73L2 of the developing sleeve 70, with the center line 73L0 of the vibration of the outer diameter of the developing sleeve 70 as the center. Therefore, by measuring the vibration of the outer diameter of the developing sleeve 70, the center of the vibration of the outer diameter of the developing sleeve 70 can be detected. Therefore, the center line 73L0 of the vibration of the outer diameter of the developing sleeve 70 is detected, and the size of the SB gap G can be measured from the center line 73L0 of the vibration of the outer diameter of the developing sleeve 70. This makes it possible to suppress variation in the position of the tip 36e of the doctor blade 36 caused by the difference in phase between the developing sleeve 70 when stopped at a position far from the doctor blade 36 and when stopped at a position close to the doctor blade 36.

Therefore, by using a developing sleeve 70 of the same precision and a doctor blade 36 of the same precision, and by using the same SB gap G adjustment value while rotating the developing sleeve 70, it is possible to reproduce the position of the tip 36e of the doctor blade 36 in the same position. This makes it possible to reduce manufacturing variations.

As mentioned above, the straightness of the surface of the developing sleeve 70 is within ±15 μm, but in order to adjust the SB gap with higher precision, it is necessary to consider not only the straightness of the coating amount control surface 36r of the doctor blade 36, but also the straightness of the surface of the developing sleeve 70. Therefore, in the positioning process, the finger 101 moves the doctor blade 36 in parallel in a direction that brings the doctor blade 36 closer to the surface of the developing sleeve 70, while performing the following operation with the doctor blade 36 landed on the blade attachment surface 41s.

Before landing the doctor blade 36 on the blade mounting surface 41s, the device 100 applies a straightness correction force to the doctor blade 36 via the gripping portion 37 of the doctor blade 36 to correct the straightness of the coat amount control surface 36r. That is, before landing the doctor blade 36 on the blade mounting surface 41s, the device 100 pre-corrects the straightness of the coat amount control surface 36r to 50 μm or less. Then, the device 100 lands the doctor blade 36, with the straightness of the coat amount control surface 36r corrected to 50 μm or less, on the blade mounting surface 41s.

Next, the device 100 applies an adjustment force to the doctor blade 36 via the gripping portion 37 of the doctor blade 36 to adjust the relative position of the coat amount control surface 36r of the doctor blade 36 with respect to the developing sleeve 70 in order to set the SB gap G within a predetermined range (i.e., the adjustment range of the SB gap G) when the doctor blade 36 is fixed to the blade mounting portion 41. That is, the finger 101 bends at least a part of the area corresponding to the maximum image area of the doctor blade 36 so that the SB gap G measured by the camera 104 is within the adjustment range of the SB gap G when the doctor blade 36 lands on the blade mounting surface 41s. At this time, at least a part of the area corresponding to the maximum image area of the doctor blade 36 is bent in a direction in which the doctor blade 36 attached to the blade mounting portion 41 approaches or moves away from the developing sleeve 70 supported by the sleeve support portion 42.

This allows for more precise adjustment of the SB gap G, taking into account not only the straightness of the coating amount control surface 36r of the doctor blade 36 but also the straightness of the surface of the developing sleeve 70. It also makes it possible to adjust the relative position of the coating amount control surface 36r of the doctor blade 36 with respect to the developing sleeve 70 so that the tolerance of the SB gap G is 60 μm or less along the longitudinal direction of the developing sleeve 70. In this case, after the relative position of the coating amount control surface 36r with respect to the developing sleeve 70 is adjusted so that the tolerance of the SB gap G is 60 μm or less along the longitudinal direction of the developing sleeve 70, the doctor blade 36 is fixed to the blade attachment portion 41 by a fixing process described below.

When the straightness of the surface of the developing sleeve 70 is more precise (for example, ±5 μm or less), the SB gap G can be adjusted with consideration given to the straightness of the coat amount control surface 36r, and it is not essential to take the straightness of the surface of the developing sleeve 70 into consideration. Similarly, when the latitude of the SB gap G is large, the SB gap G is adjusted with consideration given to the straightness of the coat amount control surface 36r of the doctor blade 36, but it is not essential to take the straightness of the surface of the developing sleeve 70 into consideration.

(3) Fixing Step Next, the details of the fixing step will be described with reference to the schematic diagram of Fig. 12. In the first embodiment, as shown in Fig. 12, the fixing step is performed in a state where the doctor blade 36, which has been bent in the bending step, is landed at a predetermined position of the blade attachment portion 41 of the developing frame 30 determined in the positioning step.

In the first embodiment, the device 100 applies adhesive A to the blade mounting surface 41s over substantially the entire area corresponding to the maximum image area before the doctor blade 36 lands on the blade mounting surface 41s of the developing frame 30. The doctor blade 36, which has been bent in the bending process, is then adhered (fixed) to the blade mounting portion 41 over substantially the entire area corresponding to the maximum image area. At this time, the doctor blade 36 is adhered (fixed) to the blade mounting portion 41 with the straightness of the coat amount control surface 36r corrected to 50 μm or less.

That is, in the first embodiment, the area of the doctor blade 36 that corresponds to the maximum image area and that is deflected to correct the straightness of the coat amount control surface 36r is fixed to the blade attachment portion 41. This makes it possible to prevent the area of the doctor blade 36 that corresponds to the maximum image area and that is deflected to correct the straightness of the coat amount control surface 36r from returning from the deflected state to its original state before deflection.

On the other hand, depending on the shape of the blade attachment portion 41, there may be areas where it is difficult for the device 100 to apply adhesive A to the blade attachment surface 41s. In such a case, as long as the area that receives the force to deflect at least a part of the area corresponding to the maximum image area of the doctor blade 36 is fixed to the blade attachment portion 41 by adhesive A, it is not necessary for adhesive A to be applied to a part of the blade attachment surface 41s.

Therefore, when adhesive A is applied over substantially the entire area of the area corresponding to the maximum image area on the blade attachment surface 41s, it means that the following conditions are met: Adhesive A is applied over 95% or more of the area corresponding to the maximum image area in the longitudinal direction of the blade attachment surface 41s, including the area of the doctor blade 36 that is bent to correct the straightness of the coat amount control surface 36r.

When selecting adhesive A, it is necessary that it has an adhesive strength sufficient to prevent the doctor blade 36 from peeling off from the blade attachment surface 41s of the developing frame 30 during the image formation operation (development operation). The load applied to the doctor blade 36 during the image formation operation (development operation) is approximately 2 kgf in a drop test, and there is no problem if the doctor blade 36 does not peel off from the blade attachment surface 41s of the developing frame 30 under that load. Therefore, it is known that a general adhesive A can ensure sufficient adhesive strength, and from the perspective of ensuring mass productivity, the shorter the curing time of adhesive A, the better.

Next, we will explain the film thickness of the adhesive A applied to the blade mounting surface 41s of the developing frame 30. Since the doctor blade 36 and the blade mounting surface 41s of the developing frame 30 are joined using the adhesive A, the adhesive A is interposed between the doctor blade 36 and the blade mounting surface 41s of the developing frame 30. Therefore, it is necessary to consider the film thickness of the adhesive A applied to the blade mounting surface 41s so that the adhesive A interposed between the doctor blade 36 and the blade mounting surface 41s of the developing frame 30 does not affect the size of the SB gap G.

Regarding the relationship between the film thickness of adhesive A and the magnitude of the breaking load of the part bonded with adhesive A, the greater the amount of adhesive A, the greater the adhesive strength of adhesive A. As mentioned above, the magnitude of the load applied to the doctor blade 36 during the image forming operation (developing operation) is about 2 kgf, and to allow for a margin, in the first embodiment, the strength required for the adhesive strength of adhesive A is set to 10 kgf or more. Therefore, to ensure that the adhesive strength of adhesive A is 10 kgf or more, the film thickness of adhesive A applied to the blade attachment surface 41s of the developing frame 30 should be 20 μm or more.

Next, the relationship between the thickness of the adhesive A applied and the magnitude of the dimensional fluctuation of the adhesive A in the thickness direction will be described. Generally, the larger the film thickness of the adhesive A, the greater the dimensional fluctuation of the adhesive A in the thickness direction due to the shrinkage of the adhesive A when the adhesive A hardens. On the other hand, the magnitude of the dimensional fluctuation of the adhesive A in the thickness direction when the film thickness of the adhesive A is 150 μm is only about 8 μm larger than the magnitude of the dimensional fluctuation of the adhesive A in the thickness direction when the film thickness of the adhesive A is 30 μm. If the difference in the magnitude of the dimensional fluctuation of the adhesive A in the thickness direction is about 8 μm, it is at a level that can be ignored as the influence of the dimensional fluctuation in the direction perpendicular to the thickness direction of the adhesive A (i.e., the direction that defines the SB gap G). Therefore, the upper limit of the film thickness of the adhesive A applied to the blade mounting surface 41s of the developing frame 30 is not determined by the influence of the shrinkage of the adhesive A, but may be determined by individual production requirements such as the curing time and cost of the adhesive A.

In the first embodiment, the adhesive A is applied to the blade mounting portion 41 side, but the adhesive A may be applied to the doctor blade 36 side, or to both the blade mounting portion 41 side and the doctor blade 36 side. If the adhesive A is applied to the blade mounting portion 41 side prior to the start of the positioning process (more preferably, in parallel with the bending process), the total time required for the series of steps in the method for fixing the doctor blade 36 can be shortened. That is, in this example, it means a series of steps in which the adhesive A is applied to the blade mounting portion 41 of the developing frame 30 while correcting the straightness of the coat amount control surface 36r. Therefore, in the first embodiment, the following description will be given assuming that the process of applying the adhesive A to the blade mounting portion 41 of the developing frame 30 is performed prior to the start of the positioning process.

When the doctor blade 36 is fixed with adhesive A, if the adhesive A hardens during the adjustment of the SB gap G for the doctor blade 36 that has landed on the blade attachment surface 41s in the positioning process, the SB gap G cannot be adjusted thereafter. Therefore, the adjustment of the SB gap G must be completed before the adhesive A hardens. The time it takes for the adhesive A to harden is determined by the material of the adhesive A and the amount of adhesive A applied. Therefore, the time it takes for the adhesive A to harden can be predicted to some extent. Therefore, the number of times that the SB gap G can be repeatedly adjusted before the adhesive A hardens is determined in advance from the time required for each adjustment of the SB gap G. Therefore, within that number of times, the adhesive A has not yet hardened, so the SB gap G can be repeatedly adjusted.

In addition, if repeated adjustment of the SB gap G is prioritized over shortening the total time required for the series of steps of the fixing method of the doctor blade 36, a modified example in which adhesive A is applied to the blade mounting portion 41 side after the positioning step is completed may be used. In this modified example, the device 100 stores in a memory of the device 100 information on the position at which the doctor blade 36 is fixed to the blade mounting surface 41s of the developing frame 30, which is determined by adjusting the SB gap G in the positioning step. Then, after the positioning step is completed, the device 100 performs a step of applying adhesive A to the blade mounting portion 41 side of the developing frame 30. Then, after adhesive A is applied to the blade mounting portion 41 side, the device 100 lands the doctor blade 36 in a state in which it has been bent in the bending step on the blade mounting surface 41s of the developing frame 30 based on the information on the fixing position of the doctor blade 36 stored in the memory. Then, after the doctor blade 36 in its bent state lands on the blade mounting surface 41s, the device 100 can start the fixing process described above.

After completing the adjustment of the SB gap G, in order to achieve the desired adhesive strength between the doctor blade 36 and the blade attachment portion 41 of the developing frame 30, it is necessary to keep the doctor blade 36 in close contact with the blade attachment portion 41 until the adhesive A hardens. In order to bond the doctor blade 36 to the blade attachment portion 41 with sufficient adhesive strength, the degree of adhesion between the doctor blade 36 and the blade attachment portion 41 is important. This is because if the gap between the doctor blade 36 and the blade attachment portion 41 is large, the adhesive strength will be weak even if adhesive A is present in the gap.

Therefore, in order to bring the doctor blade 36 into close contact with the blade mounting portion 41, a certain load must be applied. Specifically, the device 100 drops a weight of a certain weight onto the doctor blade 36 with the doctor blade 36 in a state where it is landed on the blade mounting surface 41s of the developing frame 30, and applies a load to bring the doctor blade 36 into close contact with the blade mounting portion 41. In order to obtain sufficient adhesive strength, the finger 101 must continue to hold the doctor blade 36 in a state where such a load is applied and the doctor blade 36 is in close contact with the blade mounting portion 41 for a period of time until the adhesive A is sufficiently cured. For example, if the curing time of the adhesive A is 15 seconds, the load to bring the doctor blade 36 into close contact with the blade mounting portion 41 can be set to be applied for 20 seconds with a margin of error.

After the doctor blade 36 has been attached to the blade attachment portion 41, the device 100 raises the weight to remove the load from the doctor blade 36. The device 100 then operates the fingers 101 (101p1 to 101p5) to move the fingers 101 (101p1 to 101p5) away from the doctor blade 36, and then moves the fingers 101 (101p1 to 101p5) to a preparation position for the next operation.

The above is the details of the steps of the fixing method of the doctor blade 36. In the above-described series of fixing methods, the device 100 preliminarily corrects the straightness of the coat amount control surface 36r to 50 μm or less before landing the doctor blade 36, whose coat amount control surface 36r has an accuracy of about 300 μm to 500 μm, on the blade mounting surface 41s. As a result, even if a resin doctor blade 36 with a low accuracy of straightness of the coat amount control surface 36r is used, an example has been described in which the SB gap G can be placed within the adjustment range of the SB gap G when the doctor blade 36 is fixed to the blade mounting part 41. In this example, the function for performing the bending process and the function for performing the positioning process are provided in separate devices 100. That is, the doctor blade 36 (single unit) is placed on the mounting table 103 of the device 100 for performing the bending process, which is a device separate from the device 100 for performing the positioning process. The device 100 for performing the bending process applies a force to the doctor blade 36 to bend at least a portion of the area corresponding to the maximum image area of the doctor blade 36 while the doctor blade 36 (single unit) is placed on the stand 103.

On the other hand, a modified example in which a function for performing the deflection process and a function for performing the positioning process are both provided in one device 100 is also conceivable. In this modified example, the one device 100 does not correct the straightness of the coat amount control surface 36r to 50 μm or less before landing the doctor blade 36, whose accuracy of the coat amount control surface 36r is about 300 μm to 500 μm, on the blade mounting surface 41s. Instead, the one device 100 deflects at least a part of the area corresponding to the maximum image area of the doctor blade 36 so that the SB gap G falls within the adjustment range of the SB gap G, after landing the doctor blade 36 on the blade mounting surface 41s and before the adhesive A hardens. That is, in this modified example, a series of steps is meant in which the doctor blade 36 is fixed to the blade mounting surface 41s while at least a part of the area corresponding to the maximum image area of the doctor blade 36 is deflected to bring the SB gap G within a predetermined range (i.e., the adjustment range of the SB gap G). As a result, even if a resin doctor blade 36 with low straightness accuracy of the coating amount control surface 36r is used, when the doctor blade 36 is fixed to the blade attachment portion 41, the SB gap G can be within the SB gap G adjustment range.

However, as mentioned above, when a resin doctor blade for A3 size is manufactured with the accuracy of a general resin molded product, the straightness of the coat amount control surface is about 300 μm to 500 μm. For this reason, it is preferable for the device 100 to correct the straightness of the coat amount control surface 36r to 50 μm or less before landing the doctor blade 36 on the blade mounting surface 41s. This is because the SB gap G is adjusted with the straightness of the coat amount control surface 36r corrected to 50 μm or less, so the adjustment time is shorter than when the SB gap G is adjusted with the straightness of the coat amount control surface 36r being about 300 μm to 500 μm. In other words, the time required for the process performed with the doctor blade 36 landed on the blade mounting surface 41s (the adjustment time of the SB gap G) is shorter, so the time until the adhesive A applied to the blade mounting surface 41s hardens can be set shorter. Furthermore, having the function for performing the deflection process and the function for performing the positioning process in separate devices 100 is advantageous in terms of mass production, since the takt time can generally be shortened compared to having both functions in a single device 100.

Next, the deformation of the doctor blade 36 caused by the agent pressure generated by the developer flow acting on the doctor blade 36 during the image forming operation (developing operation) will be described using the cross-sectional view of FIG. 15. FIG. 15 is a cross-sectional view of the developing device 3 taken along a cross section (cross section H in FIG. 2) perpendicular to the rotation axis of the developing sleeve 70. FIG. 15 also shows the configuration in the vicinity of the doctor blade 36 fixed to the blade attachment portion 41 of the developing frame 30 by adhesive A.

As shown in FIG. 15, the line connecting the closest position of the doctor blade 36 to the developing sleeve 70 on the coating amount control surface 36r and the center of rotation of the developing sleeve 70 is the X-axis. At this time, the doctor blade 36 is long in the X-axis direction, and the rigidity in the cross section in the X-axis direction is large. Also, as shown in FIG. 15, the proportion of the cross-sectional area T1 of the doctor blade 36 to the cross-sectional area T2 of the wall portion 30a of the developing frame 30 located near the developer guide portion 35 is small. As described above, in the first embodiment, the rigidity of the developing frame 30 (single unit) is 10 times or more larger than the rigidity of the doctor blade 36 (single unit). Therefore, when the doctor blade 36 is fixed to the blade attachment portion 41 of the developing frame 30, the rigidity of the developing frame 30 becomes dominant with respect to the doctor blade 36. As a result, during the image formation operation (development operation), the displacement (maximum deflection) of the coat amount control surface 36r of the doctor blade 36 when the doctor blade 36 is subjected to developer pressure becomes substantially equivalent to the displacement (maximum deflection) of the developing frame 30.

During the image forming operation (developing operation), the developer pumped up from the first conveying screw 33 passes through the developer guide portion 35 and is transported to the surface of the developing sleeve 70. After that, even when the doctor blade 36 determines the layer thickness of the developer to the size of the SB gap G, the doctor blade 36 receives developer pressure from various directions. As shown in FIG. 15, when the direction perpendicular to the X-axis direction (the direction that determines the SB gap G) is the Y-axis direction, the developer pressure in the Y-axis direction is perpendicular to the blade mounting surface 41s of the developing frame 30. That is, the developer pressure in the Y-axis direction is a force in the direction that peels the doctor blade 36 off the blade mounting surface 41s. Therefore, the bonding force of the adhesive A needs to be sufficiently large relative to the agent pressure in the Y-axis direction. Therefore, in the first embodiment, the adhesive area and coating thickness of the adhesive A to the blade mounting surface 41s are optimized in consideration of the force that tries to peel the doctor blade 36 off the blade mounting surface 41s due to the agent pressure and the adhesive force of the adhesive A. In addition, in the first embodiment, the cross-sectional area T2 of the wall portion 30a of the developing frame 30 is made sufficiently large to withstand the developer pressure in the Y-axis direction that the developer guide portion 35 receives, so deformation of the doctor blade 36 due to the developer pressure during the image formation operation (development operation) can be suppressed.

Next, the deformation of the doctor blade 36 caused by temperature changes due to heat generated during the image forming operation (developing operation) will be described using the perspective view of Figure 16. Examples of heat generated during the developing operation include heat generated when the rotating shaft of the developing sleeve 70 and the bearing 71 rotate, heat generated when the rotating shaft 33a of the first conveying screw 33 and the bearing member rotate, and heat generated when the developer passes through the SB gap G. These heats generated during the image forming operation (developing operation) change the temperature around the developing device 3, and the temperatures of the doctor blade 36, the developing frame 30, and the cover frame 40 also change.

On the other hand, if the linear expansion coefficient α1 of the resin constituting the doctor blade 36 is different from the linear expansion coefficient α2 of the resin constituting the developing frame 30, the amount of deformation due to temperature change will differ due to the difference in these linear expansion coefficients. As described above, in the first embodiment, a method is adopted in which the doctor blade 36 is fixed to the blade attachment portion 41 of the developing frame 30 by adhesive A over almost the entire area corresponding to the maximum image area. In addition, if there is a large difference between the linear thermal expansion coefficient α2 of the resin constituting the developing frame 30 and the linear thermal expansion coefficient α1 of the resin constituting the doctor blade 36, the following problem occurs when a temperature change occurs. That is, when a temperature change occurs, the amount of deformation (amount of expansion and contraction) of the doctor blade 36 due to the temperature change will differ from the amount of deformation (amount of expansion and contraction) of the developing frame 30 due to the temperature change.

For example, suppose that at least a first region, a second region, and a third region (e.g., three or more regions including both ends and the center of the region corresponding to the maximum image area of the doctor blade 36) are fixed to the blade mounting surface 41s. In this case, the amount of thermal expansion differs between the center and both ends of the doctor blade 36, so the doctor blade 36 may bend significantly and warp significantly. As a result, even if the SB gap G is adjusted with high precision when determining the position for mounting the doctor blade 36 to the blade mounting surface 41s of the developing frame 30, the size of the SB gap G will fluctuate due to temperature changes during the image formation operation (development operation).

In the first embodiment, the doctor blade 36 is fixed to the blade attachment surface 41s over almost the entire area corresponding to the maximum image area, so it is necessary to suppress fluctuations in the size of the SB gap G caused by temperature changes during the image formation operation (development operation).

16, the amount of expansion of the doctor blade 36 due to temperature change is H [μm], and the amount of expansion of the blade mounting surface 41s of the blade mounting portion 41 of the developing frame 30 due to temperature change is I [μm]. In addition, the linear expansion coefficient α1 of the resin constituting the doctor blade 36 is different from the linear expansion coefficient α2 of the resin constituting the developing frame 30. In this case, the difference in these linear expansion coefficients causes the amount of deformation of the developing frame 30 and the doctor blade 36 due to temperature change to differ, and in order to compensate for the difference between H [μm] and I [μm], the doctor blade 36 deforms in the direction of arrow J in FIG. 16. The deformation of the doctor blade 36 in the direction of arrow J in FIG. 16 will be referred to hereinafter as the deformation in the warping direction of the doctor blade 36. The deformation in the warping direction of the doctor blade 36 leads to a change in the size of the SB gap G. In order to suppress fluctuations in the size of the SB gap G caused by heat, the linear expansion coefficient α2 of the resin that constitutes the sleeve support portion 42 and blade attachment portion 41 of the developing frame 30 (single unit) and the linear expansion coefficient α1 of the resin that constitutes the doctor blade 36 (single unit) are related to each other.

Hereinafter, the difference between the linear expansion coefficient α1 of the resin constituting the doctor blade 36 and the linear expansion coefficient α2 of the resin constituting the developing frame 30 having the sleeve support portion 42 and the blade attachment portion 41 will be referred to as the linear expansion coefficient difference α2-α1. The change in the maximum deflection amount of the doctor blade 36 due to this linear expansion coefficient difference α2-α1 will be explained using Table 1. With the doctor blade 36 fixed to the blade attachment portion 41 of the developing frame 30 over almost the entire area corresponding to the maximum image area, the maximum deflection amount of the doctor blade 36 was measured when a temperature change from room temperature (23°C) to a high temperature (40°C) was applied.

The linear expansion coefficient of the resin that constitutes the developing frame 30 having the sleeve support portion 42 and the blade attachment portion 41 is α2 [m/°C], and the linear expansion coefficient of the resin that constitutes the doctor blade 36 is α1 [m/°C]. The parameter of the linear expansion coefficient difference α2-α1 was then changed to measure the maximum deflection of the doctor blade 36, and the results are shown in Table 1.

As mentioned above, in order to suppress unevenness in the amount of developer carried on the surface of the developing sleeve 70 in the longitudinal direction of the developing sleeve 70, the fluctuation amount of the SB gap G caused by heat generally needs to be suppressed to ±20 μm or less. Therefore, in Table 1, when the absolute value of the maximum deflection amount of the doctor blade 36 is 20 μm or less, the maximum deflection amount is indicated as "O", and when the absolute value of the maximum deflection amount of the doctor blade 36 is greater than 20 μm, the maximum deflection amount is indicated as "X".

As can be seen from Table 1, in order to suppress the amount of variation in the SB gap G due to heat to within ±20 μm, the linear expansion coefficient difference α2−α1 needs to satisfy the following relational expression (Equation 1).
(Equation 1)
-0.45×10 ^-5 [m/℃]≦α2-α1≦0.55×10 ^-5 [m/℃]

Therefore, the resin constituting the developing frame 30 and the resin constituting the doctor blade 36 should be selected so that the linear expansion coefficient difference α2-α1 is -0.45×10 ^-5 [m/°C] or more and 0.55×10 ^-5 [m/°C] or less. By selecting resins constituting the developing frame 30 and the doctor blade 36 such that the linear expansion coefficient difference α2-α1 satisfies (Equation 1), the fluctuation amount of the SB gap G caused by heat can be suppressed to ±20 μm or less. It is more preferable to make the linear expansion coefficient difference α2-α1 zero. In order to make the linear expansion coefficient difference α2-α1 zero, the same resin should be selected for the developing frame 30 and the doctor blade 36.

In addition, because the cover frame 40 is fixed to the developing frame 30, if the amount of deformation of the developing frame 30 and the cover frame 40 due to temperature changes differs, the deformation in the warping direction of the cover frame 40 will lead to fluctuations in the size of the SB gap G. As a result, even if the SB gap G is adjusted with high precision in the positioning process of the doctor blade 36, there is a risk that the size of the SB gap G will fluctuate due to temperature changes during the image formation operation (development operation).

To suppress the fluctuation in the size of the SB gap G caused by temperature changes, the linear expansion coefficient α2 of the resin that constitutes the sleeve support portion 42 and blade attachment portion 41 of the developing frame 30 (single unit) and the linear expansion coefficient α3 of the resin that constitutes the cover frame 40 (single unit) are related. As mentioned above, it is necessary to suppress the amount of fluctuation in the SB gap G caused by heat to ±20 μm or less. The linear expansion coefficient of the resin that constitutes the developing frame 30 having the sleeve support portion 42 and blade attachment portion 41 is α2 [m/°C], and the linear expansion coefficient of the resin that constitutes the cover frame 40 is α3 [m/°C].

Hereinafter, the difference between the linear expansion coefficient α2 of the resin constituting the developing frame 30 having the sleeve support portion 42 and the blade attachment portion 41 and the linear expansion coefficient α3 of the resin constituting the cover frame 40 will be referred to as the linear expansion coefficient difference α3-α2. As with Table 1, it is necessary for this linear expansion coefficient difference α3-α2 to satisfy the following relational expression (Equation 2).
(Equation 2)
-0.45×10 ^-5 [m/℃]≦α3-α2≦0.55×10 ^-5 [m/℃]

Therefore, the resin constituting the developing frame 30 and the resin constituting the cover frame 40 may be selected so that the linear expansion coefficient difference α3-α2 is -0.45× ^10-5 [m/°C] or more and 0.55× ^10-5 [m/°C] or less. By selecting resins constituting the developing frame 30 and the cover frame 40 such that the linear expansion coefficient difference α3-α2 satisfies (Equation 2), the amount of fluctuation in the SB gap G caused by heat can be suppressed to ±20 μm or less. It is more preferable to make the linear expansion coefficient difference α3-α2 zero. In order to make the linear expansion coefficient difference α3-α2 zero, the same resin may be selected as the resin constituting the developing frame 30 and the resin constituting the cover frame 40.

When adhesive A is applied to the doctor blade 36 and the developing frame 30, the linear expansion coefficient of the doctor blade 36 and the developing frame 30 to which adhesive A is applied will vary. However, the volume of adhesive A applied to the doctor blade 36 and the developing frame 30 is very small, and the effect on dimensional fluctuations in the thickness direction of adhesive A due to temperature changes is negligible. Therefore, when adhesive A is applied to the doctor blade 36 and the developing frame 30, the deformation in the warping direction of the doctor blade 36 caused by fluctuations in the linear expansion coefficient difference α2-α1 is negligible.

Generally speaking, resin molded products tend to have poorer abrasion resistance than metal molded products. Factors affecting the abrasion resistance of the doctor blade 36 include the agent pressure applied to the doctor blade 36. When selecting a resin for the doctor blade 36, it is generally known that the greater the surface hardness of the resin, the better the abrasion resistance.

Therefore, taking into consideration wear resistance, a resin having a surface hardness of 100 or more on the L scale of Rockwell hardness (JIS K7202-2) is selected as the resin for the doctor blade 36. This makes it possible to suppress wear of the doctor blade 36 during the image formation operation (development operation). The doctor blade 36 made of such a resin only wears to 10 μm or less even in a durability test equivalent to about 500,000 sheets. The greater the surface hardness of the doctor blade 36, the more improved the wear resistance of the doctor blade 36 becomes, but the mass productivity of the doctor blade 36 tends to decrease. This is because resins with high surface hardness generally contain a large amount of reinforcing agent such as glass fiber. When molding a resin with such high surface hardness in a mold, the reinforcing agent added to the resin will damage the mold. Therefore, if a certain amount or more of reinforcing agent is added to the resin, the mass productivity of the doctor blade 36 cannot be maintained. Therefore, it has been found that mass production of doctor blade 36 can be ensured by selecting a resin that has a surface hardness of 100 or less on the M scale of Rockwell hardness (JIS K7202-2) as the resin that constitutes doctor blade 36.

In the first embodiment, in consideration of both the wear resistance and mass production of the doctor blade 36, the doctor blade 36 is molded from a resin having a surface hardness of 100 or more on the Rockwell hardness L scale and 100 or less on the Rockwell hardness M scale. Examples of resins having a surface hardness of 100 or more on the Rockwell hardness L scale and 100 or less on the Rockwell hardness M scale include the following. For example, a resin (hereinafter referred to as resin X) based on polyphenylene ether (PPE) and polystyrene (PS) and containing 30% to 35% by weight of a reinforcing agent is included. Another example is a resin (hereinafter referred to as resin Y) based on polycarbonate (PC) and acrylonitrile butadiene styrene (ABS) and containing 20% to 30% by weight of a reinforcing agent is included.

In this case, the resin that constitutes the doctor blade 36 is selected to be "resin X" or "resin Y" in consideration of both the wear resistance and mass productivity of the doctor blade 36. In this case, the resin that constitutes the developing frame 30 should be selected so that the difference between the linear expansion coefficient α1 of the doctor blade 36 and the linear expansion coefficient α2 of the developing frame 30 (linear expansion coefficient difference α2-α1) satisfies the above-mentioned (Equation 1).

When "resin X" is selected as the resin that constitutes the doctor blade 36, if "resin X" or "resin Y" is selected as the resin that constitutes the developing frame 30, the linear expansion coefficient difference α2-α1 satisfies the above-mentioned (formula 1). When "resin Y" is selected as the resin that constitutes the doctor blade 36, if "resin X" or "resin Y" is selected as the resin that constitutes the developing frame 30, the linear expansion coefficient difference α2-α1 satisfies the above-mentioned (formula 1).

On the other hand, if "resin X" is selected as the resin constituting the developing frame 30, then "resin X" or "resin Y" can be selected as the resin constituting the cover frame 40. In this case, the difference in the linear expansion coefficient α2 of the developing frame 30 relative to the linear expansion coefficient α3 of the cover frame 40 (linear expansion coefficient difference α2 - α3) satisfies the above-mentioned (equation 2). Also, if "resin Y" is selected as the resin constituting the developing frame 30, then the linear expansion coefficient difference α2 - α3 satisfies the above-mentioned (equation 2) if "resin X" or "resin Y" is selected as the resin constituting the cover frame 40.

As described above, in the first embodiment, a doctor blade 36 is used in which the straightness accuracy of the coating amount control surface 36r is the same as that of a typical resin molded product. Then, a part of the area of the doctor blade 36 corresponding to the maximum image area is bent to correct the straightness of the coating amount control surface 36r, and the doctor blade 36 is fixed to the blade attachment surface 41s over substantially the entire area corresponding to the maximum image area. With this configuration, even if a resin doctor blade compatible with A3 size, which has a low straightness accuracy of the coating amount control surface 36r, is used, the SB gap G can be set within a range of approximately 300 μm ± 30 μm (i.e., the adjustment range of the SB gap G) over the longitudinal direction of the developing sleeve.

In the first embodiment, the resin constituting the doctor blade 36 was selected taking into consideration both the wear resistance and mass productivity of the doctor blade 36. The resin constituting the developing frame 30 was selected so that the difference between the linear expansion coefficient α1 of the doctor blade 36 and the linear expansion coefficient α2 of the developing frame 30 (linear expansion coefficient difference α2-α1) satisfies the above-mentioned (Formula 1). Furthermore, the resin constituting the cover frame 40 was selected so that the difference between the linear expansion coefficient α2 of the developing frame 30 and the linear expansion coefficient α3 of the cover frame 40 (linear expansion coefficient difference α2-α3) satisfies the above-mentioned (Formula 2). As a result, it is possible to suppress fluctuations in the size of the SB gap G caused by temperature changes during the image forming operation (developing operation).

In addition, in the first embodiment, the doctor blade 36 is fixed to the blade attachment portion 41 of the developing frame 30 over substantially the entire area corresponding to the maximum image area. This increases the rigidity of the doctor blade 36 when fixed to the developing frame 30 compared to when only both ends (two locations) of the doctor blade 36 in the longitudinal direction of the doctor blade 36 are fixed to the blade attachment portion 41. As a result, it is possible to suppress fluctuations in the size of the SB gap G caused by the agent pressure applied to the doctor blade 36 during the image formation operation (development operation).

Second Embodiment
In the above-described first embodiment, an example has been described in which the adhesive A is applied over substantially the entire area of the area corresponding to the maximum image area on the blade attachment surface 41s of the developing frame 30. By applying the adhesive A over substantially the entire area of the area corresponding to the maximum image area on the blade attachment surface 41s of the developing frame 30, the deflected area of the doctor blade 36 corresponding to the maximum image area is fixed to the blade attachment surface 41s. This prevents the deflected area of the doctor blade 36 corresponding to the maximum image area, which is deflected to correct the straightness of the coat amount control surface 36r, from returning from the deflected state to its original state before the deflection.

On the other hand, the second embodiment differs from the first embodiment in that the device 100 does not apply adhesive A to the blade mounting surface 41s of the developing frame 30 over almost the entire area corresponding to the maximum image area. In the second embodiment, the device 100 stores in memory the area of the doctor blade 36 that is deflected to correct the straightness of the coat amount control surface 36r in the area corresponding to the maximum image area. Next, based on the information on the deflected area of the doctor blade 36 stored in the memory, the device 100 determines a predetermined area to which adhesive A is applied in the area corresponding to the maximum image area of the blade mounting surface 41s of the developing frame 30. Then, the device 100 applies adhesive A to the determined predetermined area of the blade mounting surface 41s. The application width and film thickness of adhesive A applied to the blade mounting surface 41s may be determined from the adhesive strength of adhesive A and the amount of adhesive A applied, taking into account the man-hours and costs. As a result, the bent area of the doctor blade 36 that corresponds to the maximum image area is fixed to the blade attachment surface 41s.

In order to suppress the fluctuation of the size of the SB gap G caused by the agent pressure applied to the doctor blade 36 during the image forming operation (developing operation), it is necessary to increase the rigidity of the doctor blade 36 when it is fixed to the developing frame 30. Therefore, it is desirable for the device 100 to further apply adhesive A to at least three locations including both ends and the approximate center of the area corresponding to the maximum image area of the blade mounting surface 41s of the developing frame 30 in addition to the predetermined area of the determined blade mounting surface 41s. Note that the approximate center of the area corresponding to the maximum image area of the blade mounting surface 41s also covers an area that is moved in parallel to one end or the other end by a length of 10% or less of the longitudinal length of the area based on the center of the area corresponding to the maximum image area of the blade mounting surface 41s.

As a result, in addition to the deflected area of the doctor blade 36 corresponding to the maximum image area, at least three points including both ends and the approximate center of the area corresponding to the maximum image area of the doctor blade 36 are fixed to the blade attachment surface 41s. This further increases the rigidity of the doctor blade 36 when fixed to the developing frame 30, thereby suppressing fluctuations in the size of the SB gap G caused by the agent pressure applied to the doctor blade 36 during the image formation operation (development operation).

The method of fixing at least three points including both ends and the approximate center of the area corresponding to the maximum image area of the doctor blade 36 to the blade mounting surface 41s is not limited to fixing with adhesive A, but may be fixing with screws. Figure 17 is a perspective view showing the configuration of the developing device 300 in which three points, both ends and the approximate center of the area corresponding to the maximum image area of the doctor blade 36, are fixed to the blade mounting surface 41s with screws 80. Figure 18 is a cross-sectional view of the developing device 300 at section H in Figure 17, showing the configuration in the vicinity of the doctor blade 36 fixed to the blade mounting portion 41 of the developing frame 30 with screws 80. In Figure 17, the same reference numerals as in Figure 2 indicate the same configuration. Also, in Figure 18, the same reference numerals as in Figure 15 indicate the same configuration.

In the example of FIG. 17, an insert nut is inserted into the blade mounting surface 41s of the developing frame 30 at a fixed position. Then, a screw 80 is fastened to the insert nut, thereby improving the fastening force for fixing the doctor blade 36 to the blade mounting surface 41s. If the fastening force can be maintained, the insert nut can be eliminated and a self-tapping screw, in which the screw 80 itself cuts a tap when it is screwed in, can be used instead.

When fixing the doctor blade 36 to the blade mounting surface 41s with the screw 80, the doctor blade 36 can be fixed to the blade mounting surface 41s with the screw 80 after the adjustment of the SB gap G is completed in the positioning process described above. The gripping portion 37 of the doctor blade 36 is shifted by an amount equivalent to the fixing width per location by the screw 80 from the screw fastening portion provided on the doctor blade 36 for fastening to the blade mounting surface 41s with the screw 80. In the example of FIG. 17, the fixing width per location by the screw 80 corresponds to the width at which the screw 80 is fastened, and is about 5 mm.

Other Embodiments
The present invention is not limited to the above-described embodiments, and various modifications (including organic combinations of the respective embodiments) are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

In the above embodiment, as shown in FIG. 4, the developer guide portion 35 and the developing frame 30 are integrally formed, and the developer guide portion 35 and the doctor blade 36 are formed separately, but this is not limited to the above. As long as the doctor blade 36 (single unit) has a rigidity such that the finger 101 can bend the doctor blade 36, and the developer flow and developer pressure during the development operation are within the range of the design values, the developer guide portion 35 and the doctor blade 36 may be integrally formed.

In the above embodiment, as shown in FIG. 1, the image forming apparatus 60 is configured to use the intermediate transfer belt 61 as an image carrier, but this is not limited to the above. The present invention can also be applied to an image forming apparatus configured to transfer recording material by directly contacting the photosensitive drum 1 in sequence. In this case, the photosensitive drum 1 constitutes a rotatable image carrier that carries a toner image.

In the above embodiment, as shown in FIG. 2, the developing sleeve 70 rotates counterclockwise and the doctor blade 36 is disposed below the developing sleeve 70. However, this is not limited to this. The present invention can also be applied to a developing device 3 in which the developing sleeve 70 rotates clockwise and the doctor blade 36 is disposed above the developing sleeve 70.

In the above embodiment, as shown in FIG. 2, the developing device 3 is configured such that the developing chamber 31 and the stirring chamber 32 are arranged side by side in the horizontal direction, but this is not limited to the above. The present invention can also be applied to a developing device 3 configured such that the developing chamber 31 and the stirring chamber 32 are arranged side by side above and below in the direction of gravity.

In addition, in the above embodiment, the developing device 3 has been described as a single unit, but the same effect can be obtained even if the image forming section 600 (see FIG. 1) including the developing device 3 is integrated into a unit and is in the form of a process cartridge that is detachable from the image forming device 60. Furthermore, the present invention can be applied to image forming devices 60 equipped with such developing devices 3 or process cartridges, regardless of whether they are monochrome or color machines.

3 Developing device 30 Developing frame 36 Doctor blade 41 Blade attachment portion 70 Developing sleeve

Claims (18)

A manufacturing method of a developing device including a developer carrier which carries and transports a developer to a development position, a resin-made regulating blade which is disposed opposite to the developer carrier in a non-contact manner and regulates an amount of developer carried on the developer carrier, and a resin-made developing frame which has an attachment portion to which the regulating blade is attached and which supports the developer carrier, comprising:
a coating step of coating the mounting portion with an adhesive;
a positioning step of adjusting a force for bending the regulating blade so that a size of a gap between the developer carrier supported on the developing frame and the regulating blade attached to the attachment portion falls within a predetermined tolerance range along the longitudinal direction of the developer carrier after the adhesive applied to the attachment portion in the application step is brought into contact with the regulating blade and before hardening of the adhesive applied to the attachment portion in the application step is completed, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of a plurality of points in the longitudinal direction of the regulating blade;
A manufacturing method of a developing device comprising the steps of: 2. The method for manufacturing a developing device according to claim 1, wherein the positioning step includes adjusting the force while the regulating blade is landed on the mounting portion to which the adhesive is applied in the application step, and determining a position for attaching the regulating blade to the mounting portion while applying the adjusted force to each of the multiple points in the longitudinal direction of the regulating blade. The method further includes a measuring step of measuring the size of the gap,
3. The method for manufacturing a developing device according to claim 1, wherein the positioning step includes adjusting the force so that the size of the gap measured in the measurement step is within the predetermined tolerance range along the longitudinal direction of the developer carrier, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of the multiple locations in the longitudinal direction of the regulating blade. 4. The method for manufacturing a developing device according to claim 1, wherein the positioning step includes adjusting the force so that the size of the gap at each of a plurality of positions in the longitudinal direction of the developer carrier is 270 μm or more and 330 μm or less, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of the plurality of positions in the longitudinal direction of the regulating blade. 4. The method for manufacturing a developing device according to claim 3, wherein the measuring step measures the size of the gap by irradiating light from inside the developing frame toward the gap using a light source installed inside the developing frame, and imaging section installed outside the developing frame images the light emitted from the gap to the outside of the developing frame. The developer carrier is rotatable,
6. The method for manufacturing a developing device according to claim 3, wherein the measuring step measures the size of the gap while the developer carrier is rotating. The method for manufacturing a developing device according to any one of claims 1 to 6, characterized in that after the adhesive applied to the mounting portion in the application process has hardened, an absolute value of the difference between the gap values at multiple positions in the longitudinal direction of the developer carrier and the median value of the gap at the multiple positions is 10% or less of the median value. A method for manufacturing a developing device as described in any one of claims 1 to 7, characterized in that the multiple locations in the longitudinal direction of the regulating blade include one end of the area of the regulating blade corresponding to a maximum image area, the other end of the area of the regulating blade corresponding to the maximum image area, and a central portion of the area of the regulating blade corresponding to the maximum image area. The method for manufacturing a developing device according to claim 8 , wherein a length of the region of the regulating blade corresponding to the maximum image region corresponds to an A3 size. A manufacturing method of a developing device including a developer carrier which carries and transports a developer to a development position, a resin-made regulating blade which is disposed opposite to the developer carrier in a non-contact manner and regulates an amount of developer carried on the developer carrier, and a resin-made developing frame which has an attachment portion to which the regulating blade is attached and which supports the developer carrier, comprising:
a coating step of coating the regulating blade with an adhesive;
a positioning step of adjusting a force for bending the regulating blade so that a size of a gap between the developer carrier supported on the developing frame and the regulating blade attached to the attachment portion falls within a predetermined tolerance range along the longitudinal direction of the developer carrier, after the adhesive applied to the regulating blade in the application step is brought into contact with the attachment portion and before hardening of the adhesive applied to the regulating blade in the application step is completed, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of a plurality of points in the longitudinal direction of the regulating blade;
A manufacturing method of a developing device comprising the steps of: 11. The method for manufacturing a developing device according to claim 10, wherein the positioning step includes adjusting the force while the regulating blade on which the adhesive has been applied in the application step is landed on the attachment portion, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of the multiple points in the longitudinal direction of the regulating blade. The method further includes a measuring step of measuring the size of the gap,
12. The method for manufacturing a developing device according to claim 10, wherein the positioning step includes adjusting the force so that the size of the gap measured in the measurement step is within the range of the predetermined tolerance along the longitudinal direction of the developer carrier, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of the multiple locations in the longitudinal direction of the regulating blade. 13. The method for manufacturing a developing device according to claim 10, wherein the positioning step includes adjusting the force so that the size of the gap at each of a plurality of positions in the longitudinal direction of the developer carrier is 270 μm or more and 330 μm or less, and determining a position for attaching the regulating blade to the attachment portion while applying the adjusted force to each of the plurality of positions in the longitudinal direction of the regulating blade. 13. The method for manufacturing a developing device according to claim 12, wherein the measuring step measures the size of the gap by irradiating light from inside the developing frame toward the gap using a light source installed inside the developing frame, and imaging section installed outside the developing frame images the light emitted from the gap to the outside of the developing frame. The developer carrier is rotatable,
15. The method for manufacturing a developing device according to claim 12, wherein the measuring step measures the size of the gap while the developer carrier is rotating. 16. The method for manufacturing a developing device according to claim 10, wherein after the adhesive applied to the mounting portion in the application process has hardened, an absolute value of a difference between values of the gap at multiple positions in the longitudinal direction of the developer carrier and a median value of the gap at the multiple positions is 10% or less of the median value. 17. A method for manufacturing a developing device according to any one of claims 10 to 16, characterized in that the multiple locations in the longitudinal direction of the regulating blade include one end of the area of the regulating blade corresponding to a maximum image area, the other end of the area of the regulating blade corresponding to the maximum image area, and a central portion of the area of the regulating blade corresponding to the maximum image area. The method for manufacturing a developing device according to claim 17 , wherein the length of the region of the regulating blade corresponding to the maximum image region corresponds to an A3 size.

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