JP7532441B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus equipped with a developing device that develops an electrostatic latent image formed on an image carrier.

There is a developing device that includes a stirring chamber for stirring developer and a developing chamber for supplying developer to a developing sleeve. This developing device includes a developing screw in the developing chamber that transports the developer in the developing chamber in a first transport direction, and a stirring screw in the stirring chamber that transports the developer in the stirring chamber in a second transport direction opposite to the first transport direction, in a developing container. This developing device also includes a first opening that can communicate the developer in the developing chamber from the developing chamber to the stirring chamber, and a second opening that can communicate the developer in the stirring chamber from the stirring chamber to the developing chamber, and a partition that separates the developing chamber from the stirring chamber is provided in the developing container.

In the image forming device described in Patent Document 1, a rotatable winding section (winding shaft) for winding up the seal section (a pair of sealing members) is connected to the stirring screw via a gear train of the same series provided in the developing device. The image forming device is configured to be capable of transmitting driving force to the winding section and the stirring screw using a motor provided in the image forming device. Then, when the developing device is initially started up (when it starts to be used), the motor provided in the image forming device is driven to rotate the winding section and the stirring screw simultaneously.

JP 2014-81665 A

Depending on the storage conditions of the developing device when it is shipped, the initial developer filled in a sealed state in the stirring chamber may be compressed (tapping state) downstream of the stirring screw in the developer transport direction. Also, when the developing device is initially started up, the stirring screw starts to rotate with the first opening and the second opening sealed by the seal portion. In this case, the initial developer is transported by the stirring screw from the upstream side to the downstream side of the developer transport direction of the stirring screw, and because the first opening and the second opening are sealed, the initial developer accumulates downstream of the stirring screw in the developer transport direction. At this time, the pressure of the developer downstream of the stirring screw in the developer transport direction increases, and if the stirring screw is rotated in this state, the load torque of the motor for rotating the stirring screw increases.

This phenomenon of the motor's load torque increasing is particularly noticeable when the initial developer is in a tapping state. Furthermore, if the motor for rotating the mixing screw is not a high-output motor, the phenomenon of the motor's load torque increasing may cause a screw lock, which makes it impossible to rotate the mixing screw, if the load torque of the motor exceeds a certain value.

The present invention has been made in view of the above problems. An object of the present invention is to provide an image forming apparatus that is capable of suppressing screw lock during initialization of a developing device in a configuration in which a motor is used to transmit driving force to a winding section and an agitating screw, even if the motor is not a high-output motor.

In order to achieve the above object, an image forming apparatus according to one aspect of the present invention includes an image carrier, an exposure device that exposes the image carrier to light in order to form an electrostatic latent image on the image carrier, a developing rotator that carries and transports a developer containing toner and a carrier in order to develop the electrostatic latent image formed on the image carrier, a first chamber in which the developing rotator is disposed and that supplies the developer to the developing rotator, a second chamber that is partitioned from the first chamber by a partition wall and in which the developer circulates between the first chamber and the second chamber, a first communication portion that allows the developer to communicate from the first chamber to the second chamber, a second communication portion that allows the developer to communicate from the second chamber to the first chamber, a first conveying screw that is disposed in the first chamber and that conveys the developer, a second conveying screw that is disposed in the second chamber and that conveys the developer, and a screw that conveys the developer to the first communication portion and the second communication portion to accommodate an initial developer in the second chamber. a developing device having a pair of sealing members that seal each of two communicating portions, and a seal releasing mechanism that releases the seals of each of the first communicating portion and the second communicating portion by the pair of sealing members; a motor that can be rotated in each of a first rotation direction and a second rotation direction opposite to the first rotation direction, a control means for controlling the motor, a detection means for detecting a drive load of the motor when the motor is rotating and driven, and a display unit , wherein the first conveying screw conveys developer in a first conveying direction from the second communicating portion to the first communicating portion by a drive force supplied from the motor when the motor is rotating in the first rotation direction, and the second conveying screw conveys developer in a second conveying direction from the first communicating portion to the second communicating portion, the first conveying screw conveys the developer in the second conveying direction by a driving force supplied from the motor when the motor is rotationally driven in the second rotation direction, and the second conveying screw conveys the developer in the first conveying direction; the seal release mechanism has a rotatable winding shaft for winding up the pair of sealing members, and the winding shaft is rotationally driven in a winding direction by a driving force supplied from the motor when the motor is rotationally driven in the first rotation direction, and the pair of sealing members are wound around the winding shaft driven to rotate in the winding direction, thereby releasing the seals of the first communicating portion and the second communicating portion by the pair of sealing members, and the control means controls the first communicating portion and the second communicating portion to be unsealed by the pair of sealing members. In an initialization operation of the developing device, in which operation of the developing device is started with each of the first and second chambers sealed and the initial developer contained in the second chamber, if the driving load detected by the detection means while the motor is rotationally driven in the first rotation direction is equal to or greater than a predetermined value, the motor is controlled to be rotationally driven in the second rotation direction for a predetermined time, and thereafter, the motor is controlled to be rotationally driven in the first rotation direction, and if the driving load detected by the detection means while the motor is rotationally driven in the first rotation direction is equal to or greater than a predetermined value, an error is displayed on the display unit without again controlling the motor to be rotationally driven in the second rotation direction .

According to the present invention, in a configuration in which a motor is used to transmit driving force to the winding section and the stirring screw, even if the motor is not a high-output motor, it is possible to prevent screw lock from occurring during the initialization operation of the developing device.

1 is a diagram for explaining an overall configuration of an image forming apparatus according to a first embodiment; FIG. 2 is a diagram illustrating a cross-sectional configuration of a developing device according to the first embodiment. FIG. 2 is a diagram for explaining a planar configuration of the developing device according to the first embodiment. 2A and 2B are diagrams for explaining the configuration and operation of a developing device according to the first embodiment; 5A and 5B are diagrams illustrating a sealing structure for an initial developer in the developing device according to the first embodiment. 3 is a diagram illustrating a configuration of a drive gear train of a developing device according to the first embodiment. FIG. 5A to 5C are diagrams for explaining the operation of a drive mechanism of the developing device according to the first embodiment; 5A to 5C are diagrams for explaining the operation of a drive mechanism of the developing device according to the first embodiment; 6 is a flowchart for explaining a control example of an initialization operation of the developing device according to the first embodiment. 10A to 10C are diagrams illustrating the operation of a drive mechanism of a developing device according to a second embodiment.

The following describes in detail an embodiment of the present invention with reference to the accompanying drawings. Note that the following embodiment does not limit the scope of the present invention, and not all of the combinations of features described in the present 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)
1 is a diagram for explaining the overall configuration of an image forming apparatus 200. As shown in Fig. 1, the image forming apparatus 200 is a full-color printer of a tandem type intermediate transfer system in which yellow, magenta, cyan, and black image forming units Sa, Sb, Sc, and Sd are interchangeably mounted and arranged along an intermediate transfer belt 7.

In image forming station Sa, a yellow toner image is formed on photosensitive drum 1a and transferred to intermediate transfer belt 7. In image forming station Sb, a magenta toner image is formed on photosensitive drum 1b and transferred to intermediate transfer belt 7. In image forming stations Sc and Sd, a cyan toner image and a black toner image are formed on photosensitive drums 1c and 1d, respectively, and transferred to intermediate transfer belt 7.

The intermediate transfer belt 7 is stretched over primary transfer rollers 5a, 5b, 5c, 5d, opposing roller 8, tension roller 17, and tension roller 18, and is driven by opposing roller 8, which also serves as a drive roller, to rotate in the direction of arrow R7. The four-color toner image transferred to the intermediate transfer belt 7 is transported to secondary transfer section T2, where it is secondarily transferred onto recording material P taken out of recording material cassette 10 and transported to secondary transfer section T2. The recording material P is supplied to secondary transfer section T2 by a feeding and transporting device having a paper feed roller, transport roller, registration roller, etc.

The recording material P onto which the toner image has been transferred at the secondary transfer section T2 is heated and pressurized by the fixing device 13, which has a pressure roller 15 pressed against a fixing roller 14, and the toner image is fixed onto the surface. The recording material P is then discharged outside the machine.

Image forming units Sa, Sb, Sc, and Sd are configured almost identically, except that the colors of toner used in developing devices 100a, 100b, 100c, and 100d are different. In the following, image forming unit Sa will be described, and image forming units Sb, Sc, and Sd will be described by replacing the "a" at the end of the reference numerals given to the components of image forming unit Sa with "b," "c," and "d."

The image forming unit Sa is configured with a charging roller 2a, an exposure device 3a, a developing device 100a, a primary transfer roller 5a, and an auxiliary charging roller 6a arranged around a photosensitive drum 1a (image carrier).

The photosensitive drum 1a is an aluminum cylinder with a photosensitive layer with a negative charging polarity formed on the outer peripheral surface thereof, and rotates in the direction of arrow R1 at a predetermined process speed. The charging roller 2a charges the surface of the photosensitive drum 1a to a uniform negative potential.

The exposure device 3a scans a laser beam with a rotating mirror to write an electrostatic image onto the surface of the charged photosensitive drum 1a. The development device 100a develops the electrostatic image formed on the photosensitive drum 1a using a two-component developer composed of toner and carrier, forming a toner image on the photosensitive drum 1a.

The primary transfer roller 5a presses against the inner surface of the intermediate transfer belt 7 to form a primary transfer portion T1 between the photosensitive drum 1a and the intermediate transfer belt 7. By applying a positive DC voltage to the primary transfer roller 5a, the negative toner image carried on the photosensitive drum 1a is primarily transferred to the intermediate transfer belt 7. The auxiliary charging roller 6a charges the residual toner that has escaped transfer to the recording material P and remains on the photosensitive drum 1a to a negative polarity, and makes it involved in the next development by the developing device 100a.

A belt cleaner 11 is placed in contact with the intermediate transfer belt 7 at a position corresponding to the tension roller 17 in order to remove residual toner adhering to the intermediate transfer belt 7.

(Configuration of the developing device)
Fig. 2 is a diagram for explaining the cross-sectional structure of the developing device. Fig. 3 is a diagram for explaining the planar structure of the developing device. In the following, the developing devices replaceably mounted in the image forming units will be explained by omitting the suffixes a, b, c, and d that distinguish the image forming units.

As shown in FIG. 2, the developing device 100 develops an electrostatic image (electrostatic latent image) on the photosensitive drum 1 by carrying and transporting a developer containing toner and carrier on a developing sleeve 102, which is an example of a rotatable developer carrier (developing rotor). The developing sleeve 102 is rotatably arranged in an opening of the developing container 101 that faces the photosensitive drum 1. A layer thickness regulating blade 121 is arranged upstream in the rotation direction of the development area where the developing sleeve 102 and the photosensitive drum 1 face each other, and regulates the thickness of the developer carried on the developing sleeve 102.

The inside of the developing container 101 is divided into a developing chamber 101a and an agitating chamber 101b by a vertically installed partition wall 103. The developing chamber 101a and the agitating chamber 101b (circulation path) contain a two-component developer, which is a mixture of non-magnetic toner, magnetic carrier, and a small amount of external additive.

A magnet 102m is arranged inside the developing sleeve 102, with multiple magnetic poles arranged on its surface and supported non-rotatably. The developer is carried on the surface of the developing sleeve 102 by magnetic carriers bound by magnetic flux formed between the magnetic poles of the magnet 102m, and a magnetic brush is formed by electrostatically binding negatively charged toner to the surface of the positively charged carrier. The power source 52 applies an oscillating voltage in which an AC voltage is superimposed on a negative DC voltage, and transfers the negatively charged toner carried by the magnetic brush to the electrostatic image on the photosensitive drum 1.

As shown in FIG. 3, the developing container 101 is divided into two parallel spaces by a partition 103. The mixing chamber 101b and the developing chamber 101a are configured to be capable of storing and transporting two-component developer. The developing device 100 includes the mixing chamber 101b having a mixing screw 104b (second transport member) therein, the developing chamber 101a having a developing screw 104a (first transport member) therein, and a developing sleeve 102 disposed near the upper portion of the developing chamber 101a.

Through the openings 107a and 107b formed at both ends of the partition wall 103, the stirring chamber 101b and the developing chamber 101a communicate with each other, forming a circulation path for the developer. The developer is transferred from the stirring chamber 101b to the developing chamber 101a through the opening 107a, and the developer is transferred from the developing chamber 101a to the stirring chamber 101b through the opening 107b. That is, the opening 107a (second communication portion) allows the developer to communicate from the stirring chamber 101b (second chamber) to the developing chamber 101a (first chamber). Also, the opening 107b (first communication portion) allows the developer to communicate from the developing chamber 101a (first chamber) to the stirring chamber 101b (second chamber).

As the developer circulates through the circulation path configured in this way while being stirred, friction occurs between the toner particles and carrier particles, causing the toner to become negatively charged and the carrier to become positively charged. The developer is transported downstream while being stirred by the stirring screw 104b inside the stirring chamber 101b, and then passes through the opening 107a without the partition wall 103 and flows into the developing chamber 101a. The developer is then carried by the developing sleeve 102 inside the developing chamber 101a as it is transported downstream by the developing screw 104a.

A developing screw 104a, which is an example of a first transport screw, is rotatably mounted inside the developing chamber 101a, which is an example of a first chamber. When the developing screw 104a rotates, the two-component developer is transported from the upstream side to the downstream side of the developing chamber 101a, as shown by the arrow B.

A stirring screw 104b, which is an example of a second conveying screw, is rotatably mounted inside the stirring chamber 101b, which is an example of a second chamber. When the stirring screw 104b rotates, the two-component developer is conveyed from the upstream side to the downstream side of the stirring chamber 101b, as shown by the arrow A.

A toner supply mechanism 105 is disposed above the upstream side of the mixing chamber 101b. The toner contained in the toner bottle is transported to the toner supply mechanism 105 through a toner transport path, passes through a toner supply port 106, and is dropped and supplied into the mixing chamber 101b. In the developing device 100, the same type of toner as the initial developer is used as the replenishment toner.

Here, the toner charge amount Q/M of the two-component developer is an important parameter that determines the density of the developed image. There is a correlation between the weight ratio of the toner contained in the two-component developer (toner concentration T/D) and the toner charge amount Q/M.

Because toner is charged by friction when it comes into contact with the carrier, the more contact the toner has with the carrier, the greater the toner charge amount Q/M. For this reason, with two-component developer, the smaller the toner concentration T/D, the greater the toner charge amount Q/M, and the lower the image density when an equal electrostatic image is developed. For this reason, the toner concentration T/D of the developer circulating in the development chamber 101a and the mixing chamber 101b is constantly detected using the magnetic permeability sensor T. The amount of toner replenished from the toner replenishment mechanism 105 is then adjusted so that the toner concentration T/D remains approximately constant.

(Initial developer sealing structure)
Fig. 4 is a diagram for explaining the planar configuration of the developing device as viewed from above. Fig. 4 is also a diagram for explaining the configuration and operation of the developing device. Fig. 5 is a diagram for explaining the sealing structure of the initial developer in the developing device. Fig. 5 is a vertical cross section as viewed from the E-E direction in Fig. 4.

As shown in FIG. 4, the relationship between the developing device 100, the drive motor 53, the power source 52, the CPU 50 (control means), the operation panel 56, and the load detection means 58 of the drive motor 53 is shown using a block diagram. In addition, in the developing device 100, a sealing sheet 51a, which is an example of a sealing member, is attached to the opening 107a of the partition wall 103 that separates the developing container 101, and a sealing sheet 51b, which is an example of a sealing member, is attached to the opening 107b. A pair of sealing members consisting of the sealing sheet 51a and the sealing sheet 51b seal the openings 107a and 107b, respectively, to accommodate the initial developer in the stirring chamber 101b. With this configuration, in the developing device 100 at the time of shipment, the initial developer is filled in a sealed state only in the stirring chamber 101b, and at this time, no developer, neither carrier nor toner, exists inside the developing chamber 101a.

As shown in FIG. 5, the sealing sheet 51a, which is an example of a sealing member, is a sheet member that is peelably (openably) attached to the opening 107a. The sealing sheet 51a is attached to the opening 107a downstream in the conveying direction of the second conveying screw.

The sealing sheet 51a is folded upward from the lower end while sealing the opening 107a, and the tip is fixed to the winding shaft 600. Similarly, the opening 107b on the opposite side is folded upward from the lower end while sealing the opening 107b, and the tip is fixed to the common winding shaft 600.

The winding shaft 600, which is the sealing sheet opening mechanism (sealing release mechanism), is connected to the developing sleeve 102 so that rotation can be transmitted by a gear train. Therefore, as the developing sleeve 102 rotates, the winding shaft 600 winds up the sealing sheets 51a, 51b onto the winding shaft 600, opening the openings 107a, 107b. As a result, the sealing sheet opening mechanism releases the sealing of the openings 107b (first communicating portion) and the openings 107a (second communicating portion) by the sealing sheets 51a, 51b (a pair of sealing members).

The winding shaft 600 automatically peels off the sealing sheets 51a and 51b of the developing device 100 from the openings 107a and 107b without relying on the user's intervention, and circulates and distributes the developer within the developing chamber 101a and the mixing chamber 101b. This allows the developing device 100 to be ready for use.

(Drive mechanism for winding shaft)
6A and 6B are diagrams for explaining the configuration of the drive gear train of the developing device, with Fig. 6A and Fig. 6B being perspective views showing the same part from different directions.

As shown in FIG. 6, the developing device 100 has a developing screw 104a connected to a drive motor 53 installed on the main body side of the image forming device 200 via a coupling 54 (see FIG. 5) that is detachable in the direction of the rotation axis. The drive motor 53 is controlled by instructions from the CPU 50 to rotate the developing screw 104a.

Rotation is transmitted to the developing sleeve 102 by a gear 170 (see FIG. 4) provided on the shaft of the developing screw 104a, a sleeve gear 171 (see FIG. 4) provided on the rotation shaft of the developing sleeve 102, and an intermediate gear.

The rotation of the developing screw 104a is transmitted by the gear train 160 on the opposite side to which the coupling 54 is connected, and the stirring screw 104b, the developing screw 104a, and the winding shaft 600 rotate together. The developing sleeve 102, the developing screw 104a, the stirring screw 104b, and the winding shaft 600 form a single gear train by the gear train 160. When the developing screw 104a rotates, the output gear 151 attached to the end of the rotating shaft of the developing screw 104a rotates. The idler gear 150 meshing with the output gear 151 rotates the winding shaft 600 through the meshing of the gear 153 and the gear 154 connected to the winding shaft 600. The gears 153 and 154 are configured to be greatly decelerated using a worm gear and a worm wheel so that the torque required for the winding shaft 600 to peel off the sealing sheet 51a can be secured.

On the other hand, the mixing screw gear 155 that rotates the mixing screw 104b is engaged with the output gear 151.

All of these drive gear trains are connected in the same series, and are configured so that when the coupling 54 rotates, all of the gears are also driven to rotate. In addition, the gear trains in the same series refer to the drive transmission paths in which the coupling 54 and the stirring screw 104b, the coupling 54 and the winding shaft 600, and the sleeve gear 171 are directly connected through gear meshing. In addition, the gear trains branching off from the gears in series are considered to be the same as the branch gears in terms of the series, and the directly connected gear trains are considered to be in the same series, regardless of the length of the gear train after branching or the number of branches.

(Initialization of the developing device)
7 and 8 are diagrams for explaining the operation of the drive mechanism of the developing device. Fig. 8 is a cross-sectional view taken along the line F-F in Fig. 4, in which Fig. 8(a) shows the operation of the take-up part of the sealing sheet during the initialization operation of the developing device, and Fig. 8(b) shows the state when the drive gear train of the developing device is rotating in reverse. Note that the developing container 101 in Figs. 6 to 8 is omitted so that the internal structure of the developing container 101 can be seen.

When the developing device 100 is mounted on the image forming device 200, or when the power source of the image forming device 200 is mounted in the image forming device 200 at the time of shipment, power is supplied to the motor 53 of the drive source M1 provided in the image forming device 200. Then, power is supplied to the motor 53, and the rotational driving force is transmitted to the developing screw 104a via the coupling 54 provided at the end of the rotation shaft of the developing screw 104a of the developing device 100. The direction of rotation of the developing screw 104a during forward rotation is the direction of the arrow 104R shown in FIG. 6. The output gear 151 attached to the end of the rotation shaft of the developing screw 104a on the opposite side to the coupling 54 rotates and the rotation is transmitted to the idler gear 150 with which it is meshed. The output gear 151 is also meshed with the stirring screw gear 155, and the rotational force is transmitted to the stirring screw 104b. The idler gear 150 meshed with the other output gear 151 has a bevel gear 150a integrally provided at one end side. A bevel gear 152 is also provided integrally with one end of the worm gear 153, and the respective bevel gears are disposed with their rotation axes at 90° to each other and mesh with each other.

As a result, the rotational force transmitted to the idler gear 150 is transmitted to the worm gear 153 via the meshing of the bevel gears 152, 150a. The worm wheel 154 is greatly decelerated by the worm gear 153 and the worm wheel 154 and rotates in the direction of the arrow. At this time, the worm gear 153 receives a reaction force from the worm wheel 154 and the worm gear 153 itself is urged in the direction of the arrow P shown in Figure 8 (a). Therefore, the gear meshing between the bevel gear 152 and the bevel gear 150a provided on the idler gear 150 is maintained.

The worm wheel 154 is connected to the winding shaft 600 of the sealing sheet 51a so as to rotate together with it, and rotates together with the worm wheel 154 in the direction of the arrow T in FIG. 7. Meanwhile, the stirring screw gear 155 also starts to rotate in the direction of the arrow due to the rotational driving force transmitted from the idler gear 150. In this way, the winding shaft 600 and the stirring screw 104b operate simultaneously.

Next, the movement of each gear when the motor 53 rotates in reverse will be described. When the motor 53 rotates in reverse, all rotations are opposite to the arrows without symbols shown in FIG. 7. When the motor 53 rotates in reverse, the developing screw 104a and the output gear 151 rotate in the opposite direction to the arrows on the output gear 151 in FIG. 7. The idler gear 150 that meshes with the output gear 151 also rotates in the opposite direction to the arrows on the idler gear 150.

The operation of each gear at this time is shown in Figure 8 (b). As shown in Figure 8 (b), the bevel gear 152, which is integral with the worm gear 153 and meshes with the bevel gear 150a, which is integral with the idler gear 150, rotates together with the worm gear 153 in the direction of the arrow on the worm gear 153.

The worm gear 153 itself is biased in the direction of the arrow Q shown in Figure 8. The worm gear 153 is configured to be movable against the biasing force in the direction of the arrow Q, so when the motor 53 rotates in the reverse direction, the worm gear 153 moves in the direction of the arrow Q. As a result, the meshing between the bevel gear 152 and the bevel gear 150a disengages as shown in Figure 8, and when the teeth of the bevel gears separate to the limit where they come into contact, no rotational force is transmitted.

As a result, the worm wheel 154 that meshes with the worm gear 153 does not rotate, and the winding shaft 600 does not rotate either. Therefore, when the motor 53 rotates in the reverse direction, the sealing sheet 51a is not wound up and remains in that state.

Meanwhile, the other agitating screw gear 155 that is engaged with the output gear 151 rotates in the opposite direction to the arrow on the agitating screw gear 155 in FIG. 7. The agitating screw gear 155 is connected to the agitating screw 104b so that it rotates integrally with it, and so rotates in the same direction. The agitating screw 104b is formed with spiral blades so that it transports the developer in the direction of the arrow T in FIG. 7 during forward rotation, so that it transports the developer in the opposite direction to the arrow T during reverse rotation.

Therefore, when the motor 53 rotates in reverse, the developing screw 104a is configured to transport the developer in the direction opposite to the arrow T in FIG. 7, but as described above, the sealing sheet 51a is not collected. Therefore, there is no developer in the developing chamber 101a, and the developer is not actually transported in the reverse direction. The developer in the mixing chamber 101b is transported in the direction opposite to the arrow T.

(Normal initialization of the developing device)
A typical operation during initialization of the developing device will be described with reference to Figures 7 and 8. Also, a control example of the initialization operation of the developing device will be described with reference to the flowchart of Figure 9. The control of Figure 9 is executed by the CPU 50 reading out a control program stored in the memory of the image forming apparatus 200 and controlling various devices. Also, the control of Figure 9 is started after the image forming apparatus 200 receives an instruction to replace the developing device 100.

After the developing device 100 is replaced, or when the developing device 100 that is pre-installed at the time of shipment of the image forming device 200 is operated for the first time, a determination is made as to whether the developing device requires initialization (S1). The determination can be made either by using the memory of the developing device 100 or by an operator inputting information to the image forming device 200 via the operation panel 56. If the result of the developing device 100 replacement determination (S1) is NO, there is no particular need to perform initialization, and so the initialization operation ends.

If the replacement judgment (S1) of the developing device 100 is YES, the next step of the initialization operation of the developing device 100 starts (S2). After the initialization operation of the developing device 100 starts (S2), a judgment is made as to whether the drive load torque of the developing device 100 is excessive (above a predetermined value) or not until a predetermined time t1 has elapsed (S3). Note that the predetermined time t1 is a predetermined time until the sealing sheet 51a starts to be opened.

Under normal circumstances, there is no extreme bias of the developer in the stirring chamber 101b, and the rotation load of the stirring screw 104b does not become excessive (above a predetermined value) until the predetermined time t1 has elapsed. Therefore, the driving load torque of the developing device 100 does not become excessive (above a predetermined value) within the predetermined time t1, and the determination of whether the driving load torque of the developing device 100 is excessive (above a predetermined value) is NO (S3: NO). During this time, the developer in the stirring chamber 101b is gradually transported downstream in the transport direction of the stirring screw 104b, and since the winding shaft 600 is also rotating, the sealing sheet 51a is gradually wound up. Therefore, the initialization operation of the developing device 100 continues (S4). Here, the amount of current of the motor 53 is detected to detect the torque of the motor 53, but other methods may be used. For example, a method using a sensor that detects rotation or a detection of a stopped state due to loss of synchronism may be used. After that, the initialization operation of the development device 100 is confirmed to be complete after a predetermined time t2 has elapsed, and the process ends.

(Initialization Operation of the Developing Device When the Driving Load Torque of the Developing Device is Excessive)
Next, a description will be given of a case where the developer enclosed in the mixing chamber 101b is biased toward the downstream side in the transport direction of the mixing screw 104b, and the initialization operation of the developing device 100 is performed. As in the above-described normal operation description, when the developing device 100 is operated for the first time (at the start of use), a determination is made as to whether the developing device 100 requires an initialization operation (S1).

Next, if the result of the development device 100 replacement determination (S1) is NO, there is no need to perform initialization, so the initialization operation ends. If the development device 100 replacement determination (S1) is YES, the next step of the development device 100 initialization operation begins (S2).

The initialization operation (S2) of the developing device 100 is started, and a determination is made (S3) as to whether the drive load torque of the developing device 100 is excessive (above a predetermined value) until a predetermined time t1 has elapsed. If the developer in the stirring chamber 101b is biased toward the downstream side of the stirring screw 104b in the transport direction and the developer is in a compressed state (tapping state), the stirring screw 104b may stop without being able to rotate much.

This phenomenon of the load torque of the motor 53 increasing is particularly noticeable when the initial developer is in a tapping state. In addition, if the motor 53 is not a high-output motor, when the load torque of the motor 53 increases and exceeds a predetermined value, a screw lock occurs, which makes it impossible to rotate the stirring screw 104b.

Then, in S3, the determination as to whether the drive load torque of the developing device 100 is excessive (above a predetermined value) within the predetermined time t1 is YES. The method of detecting whether the drive load torque of the developing device 100 is excessive (above a predetermined value) is the same as that described in the normal initialization operation of the developing device 100 described above, and therefore will not be described here.

Then, the developing device is driven (reverse rotation) for a predetermined number of rotations n (S6). The predetermined number of rotations n is determined by determining the reverse rotation time of the motor 53 based on the number of times the stirring screw 104b rotates in reverse. A range is set in which the developer in the stirring chamber 101b, which is biased toward the downstream side of the conveying direction of the stirring screw 104b, does not move toward the upstream side of the conveying direction due to reverse rotation and become clogged in the reverse direction.

At this time, as described above in "Description of the operation when initializing the developing device 100", the sealing sheet 51a is configured so that the winding shaft 600 does not rotate. Therefore, the opening 107a of the partition 103 remains blocked by the sealing sheet 51a, and the developer is not discharged from the mixing chamber 101b to the developing chamber 101a. Therefore, the developer that has accumulated on the downstream side of the conveying direction (when rotating forward) of the mixing screw 104b in the mixing chamber 101b is conveyed while being dispersed toward the upstream side of the conveying direction (when rotating forward) of the mixing screw 104b.

The load torque during reverse rotation at this predetermined rotation speed n is then used to determine whether the drive load torque during reverse rotation of the developing device 100 is excessive (above a predetermined value) (S7). If it is determined that the drive load torque is excessive (above a predetermined value) (YES), then the drive load torque is excessive (above a predetermined value) both during forward and reverse rotation, so an abnormality determination (S12) is made and an error message is displayed on the operation panel 56.

On the other hand, if the determination (S7) as to whether the drive load torque during reverse rotation operation of the developing device 100 is excessive (greater than a predetermined value) is NO, the predetermined number of rotations n is completed (S8) and the drive of the developing device 100 is stopped (S9).

Next, the initialization operation of the developing device 100 is started (forward rotation) (S10). At this time, it is determined again within a predetermined time t1 whether the drive load torque is excessive (above a predetermined value) (S11). If the determination result of S11 is YES, the developing device 100 is not rotated in reverse again, and an error message is displayed on the operation panel 56 due to an abnormality determination (S12).

If the determination as to the start of the initialization operation of the developing device 100 (forward rotation) (S11) is NO, the process proceeds to continuation of the initialization operation of the developing device 100 (S4), and when the predetermined time t2 has elapsed, it is determined that the initialization operation of the developing device 100 has been completed, and the process ends.

In this way, even if the developer in the stirring chamber 101b is unevenly distributed and the development device 100 cannot be initialized, the developer in the stirring chamber 101b is prevented from clogging by the reverse rotation of the stirring screw 104b without winding up the sealing sheet 51a. Since the winding shaft 600 can be rotated forward immediately afterwards, the sealing sheet 51a can be wound up by the winding shaft 600 before the developer in the stirring chamber 101b accumulates and compresses again downstream in the transport direction of the stirring screw 104b (when rotating forward).

In the first embodiment described above, in a configuration in which the motor 53 is used to transmit driving force to the winding shaft 600 and the stirring screw 104b, it is possible to prevent screw lock from occurring when the development device 100 is first used, even if the motor 53 is not a high-output motor.

Second Embodiment
Next, a second embodiment will be described. The basic configuration of the second embodiment is the same as that of the first embodiment. Therefore, elements having substantially the same or corresponding functions and configurations as those of the first embodiment are given the same reference numerals, and detailed descriptions are omitted, and only the components unique to the second embodiment will be described in detail.

The operation of the drive mechanism of the developing device according to the second embodiment will be described with reference to FIG. 10. The configuration of the sealing sheet 51a and the winding shaft 600 is the same as that of the first embodiment described above, and therefore a description thereof will be omitted. In addition, the initialization operation of the developing device 100 and the control flow of FIG. 9 executed by the CPU 50 are also the same as those of the first embodiment described above, and therefore a description thereof will be omitted.

Figure 10(a) shows the operation of the drive gear train when the motor 35 is rotating forward, and Figure 10(b) shows the operating state when it is rotating reversely. The rotational force from the motor 53 (when rotating forward) is received by a coupling 54 provided on one end of the rotation shaft of the developing screw 104a. The rotational force received by the coupling 54 then rotates the developing screw 104a together with the output gear 151 provided on the other end of the rotation shaft of the developing screw 104a in the direction of the arrow shown on the output gear 151.

The rotational force of the main gear 151 is transmitted to the meshed stirring screw gear 155 and the idler gear 150. A bevel gear 150a is integrally provided on one end of the idler gear 150, as in the first embodiment described above.

The bevel gear 152, which meshes with the bevel gear 150a, is integrally formed with the worm gear 153 and rotates together with it. The worm gear 153 meshes with the worm wheel 154, which is connected to rotate integrally with the winding shaft 600 described in the first embodiment above. The idler gear 150, the worm gear 153, and the worm wheel 154 are integrally held by a swinging holder 180 that can swing around the rotation center 154a of the worm wheel 154.

In the oscillating holder 180, each gear is supported rotatably, and a force acts on the oscillating holder 180 in the direction of the arrow Sa in FIG. 10(a) due to a reaction force at the meshing portion between the output gear 151 and the idler gear 150. Therefore, the meshing between the output gear 151 and the idler gear 150 is maintained, and the rotation is transmitted to the worm wheel 154.

On the other hand, when the motor 35 rotates in the reverse direction, as shown in FIG. 10B, the agitating screw 104b connected to the agitating screw 155 rotates in the direction of the arrow on the agitating screw gear 155. Therefore, as in the first embodiment, the developer in the agitating chamber 101b is transported in the opposite direction to the transport direction (when rotating forward) of the agitating screw 104b.

In addition, the idler gear 150 meshing with the output gear 151 is in a state where it exerts a biasing force on the oscillating holder 180 in the direction of the arrow Sb shown in FIG. 10(b), unlike in the case of forward rotation. As a result, the oscillating holder 180 rotates around the rotation center 154a, and the meshing portion U between the output gear 151 and the idler gear 150 separates, so that the rotational force is not transmitted.

Therefore, when the motor 53 rotates in the reverse direction, the rotational force is not transmitted from the idler gear 150 to the downstream side of the rotation transmission, and the winding shaft 600 does not rotate, so the sealing sheet 51a is not wound and collected. In this way, the rotation of the gear is transmitted only during forward rotation by the rotation of the oscillating holder 180, and no rotational force is transmitted during reverse rotation, forming a so-called one-way clutch mechanism (including the oscillating gear).

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, an example has been described in which the winding up of the sealing sheets 51a and 51b by the winding shaft 600 is started at approximately the same time and completed at approximately the same time, but this is not limited to the above. A time difference may be provided between the timing at which the winding up of the sealing sheet 51a by the winding shaft 600 starts and the timing at which the winding up of the sealing sheet 51b by the winding shaft 600 starts. For example, the drive transmission mechanism may be configured so that the timing at which the winding up of the sealing sheet 51a by the winding shaft 600 starts is earlier than the timing at which the winding up of the sealing sheet 51b by the winding shaft 600 starts. This can further suppress an increase in the load torque of the motor 53 during the unsealing operation of the sealing sheets 51a and 51b.

In the above embodiment, as shown in FIG. 1, the image forming apparatus 100 is configured to use an intermediate transfer belt 7, but the present invention is not limited to this. It is also possible to apply the present invention to an image forming apparatus configured to transfer the recording material P by directly contacting the photosensitive drum 1 in sequence.

1 Photosensitive drum 3 Exposure device 50 CPU
51a Sealing sheet 51b Sealing sheet 53 Motor 58 Load detection means 100 Developing device 101a Developing chamber 101b Mixing chamber 102 Developing sleeve 104a Developing screw 104b Mixing screw 107a Opening 107b Opening 200 Image forming device 600 Winding shaft

Claims (4)

An image carrier;
an exposure device that exposes the image carrier to light in order to form an electrostatic latent image on the image carrier;
a developing device including: a developing rotor which carries and transports a developer containing a toner and a carrier to develop an electrostatic latent image formed on the image carrier; a first chamber in which the developing rotor is disposed and which supplies the developer to the developing rotor; a second chamber which is partitioned from the first chamber by a partition wall and in which the developer circulates between the first chamber and the second chamber; a first communication portion which allows the developer to communicate from the first chamber to the second chamber; a second communication portion which allows the developer to communicate from the second chamber to the first chamber; a first conveying screw which is disposed in the first chamber and transports the developer; a second conveying screw which is disposed in the second chamber and transports the developer; a pair of sealing members which seal the first communication portion and the second communication portion, respectively, to accommodate an initial developer in the second chamber; and a seal releasing mechanism which releases the sealing of the first communication portion and the second communication portion by the pair of sealing members;
a motor capable of being rotated in a first rotation direction and a second rotation direction opposite to the first rotation direction;
A control means for controlling the motor;
a detection means for detecting a driving load of the motor when the motor is rotating;
A display unit;
Equipped with
the first conveying screw conveys the developer in a first conveying direction from the second communicating portion to the first communicating portion by a driving force supplied from the motor when the motor is rotationally driven in the first rotation direction, and the second conveying screw conveys the developer in a second conveying direction from the first communicating portion to the second communicating portion by a driving force supplied from the motor.
when the motor is rotationally driven in the second rotation direction, the first conveying screw conveys the developer in the second conveying direction, and the second conveying screw conveys the developer in the first conveying direction, by a driving force supplied from the motor;
the seal release mechanism has a rotatable winding shaft for winding up the pair of sealing members, and when the motor is rotationally driven in the first rotation direction, the winding shaft is rotationally driven in the winding direction by a driving force supplied from the motor, and the pair of sealing members are wound up around the winding shaft rotationally driven in the winding direction, thereby releasing the sealing of the first communicating portion and the second communicating portion by the pair of sealing members,
During an initialization operation of the developing device in which operation of the developing device is started in a state in which the first communicating portion and the second communicating portion are each sealed by the pair of sealing members and the initial developer is contained in the second chamber, if the driving load detected by the detection means while the motor is rotationally driven in the first rotation direction is equal to or greater than a predetermined value, the control means controls the motor to be rotationally driven in the second rotation direction for a predetermined time, and thereafter controls the motor to be rotationally driven in the first rotation direction , and if the driving load detected by the detection means while the motor is rotationally driven in the first rotation direction is equal to or greater than a predetermined value, displays an error on the display unit without again controlling the motor to be rotationally driven in the second rotation direction.
1. An image forming apparatus comprising: The control means controls the motor to rotate in the first rotation direction until sealing of the first communication portion and the second communication portion by the pair of sealing members is released, when the driving load detected by the detection means while the motor is rotationally driven in the first rotation direction in the initialization operation is not equal to or greater than a predetermined value.
2. The image forming apparatus according to claim 1, 2. The image forming apparatus according to claim 1, wherein, in the initialization operation , when the motor is driven to rotate in the second rotation direction, the driving force supplied from the motor does not drive the winding shaft to rotate in the direction opposite to the winding direction. The seal release mechanism further includes a worm gear that is movable in a direction perpendicular to the rotation axis of the winding shaft, and a worm wheel that is connected to the winding shaft so as to rotate integrally with the winding shaft and meshes with the worm gear,
In the initialization operation , when the motor is rotationally driven in the second rotation direction , the worm gear moves in a direction perpendicular to the rotation axis of the winding shaft by the driving force supplied from the motor, so that the winding shaft is not rotationally driven in a direction opposite to the winding direction.
4. The image forming apparatus according to claim 3 .

Images