JP7487553B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming device.

Electrophotographic image forming devices (printers, copiers, facsimiles, and all-in-one machines) are equipped with cleaning devices having cleaning blades that remove residual toner remaining on image carriers such as photoreceptor drums and intermediate transfer belts. Some devices also include a lubricant supplying device that supplies lubricant onto the image carrier to reduce the friction between the image carrier and the cleaning blade and smoothly clean the residual toner on the image carrier (see, for example, Patent Document 1).

JP 2019-8276 A

In an image forming apparatus having the above-mentioned lubricant supply device, when using plain paper other than textured paper, there is no deterioration in transferability even if the amount of lubricant on the image carrier increases. However, it has been newly discovered that when forming an image on textured paper with unevenness such as embossed paper, if the amount of lubricant on the image carrier is large, the transferability of the toner image to the textured paper deteriorates.

Specifically, the inventors measured the pure water contact angle on the intermediate transfer belt as a proxy for the amount of lubricant, because the pure water contact angle on the intermediate transfer belt increases as the amount of lubricant increases, and evaluated the transferability to embossed paper relative to the pure water contact angle. Figure 1 is a graph evaluating the transferability to embossed paper relative to the pure water contact angle on the intermediate transfer belt. In Figure 1, the transferability is evaluated using a transferability rank of 1 to 5, with the higher the transferability rank number, the better the transferability. As shown in Figure 1, in the case of embossed paper, as the pure water contact angle increases, that is, as the amount of lubricant increases, the transferability deteriorates.

This tendency can also be confirmed by the presence or absence and type of correction operation in the image forming device. Correction operation is performed to correct performance related to image formation. Figure 2 is a graph evaluating the transferability to embossed paper with or without correction operation and the type of correction operation. In Figure 2, the transferability is also evaluated with a transferability rank of 1 to 5. In Figure 2, no correction operation is the transferability rank for embossed paper when an image is formed by passing one sheet of embossed paper without performing a correction operation, and is transferability rank 4. In this case, since there is no correction operation, that is, there is no operation to transfer lubricant onto the intermediate transfer belt, the lubricant is not transferred onto the intermediate transfer belt. Even if lubricant is transferred, the amount of lubricant transferred onto the intermediate transfer belt is small. Therefore, the transferability is not deteriorated.

On the other hand, in FIG. 2, correction operations A to C are the transferability ranks on embossed paper when correction operations A to C are performed and one sheet of embossed paper is passed through to form an image. Correction operations A to C have a lower transferability rank than when there is no correction operation. This is because correction operations A to C include an operation in which lubricant is transferred onto the intermediate transfer belt, so the amount of lubricant on the intermediate transfer belt is greater than when there is no correction operation. Also, the transferability ranks of correction operations A to C are correction operation A < correction operation B < correction operation C. In each of correction operations A to C, the idle rotation times a to c during which no toner image is formed on the intermediate transfer belt are a>b>c, and the transferability rank is low in correction operation A, which has the longest idle rotation time a. This is because when the idle rotation time is longer, the time for the operation in which lubricant is transferred onto the intermediate transfer belt is longer, and the amount of lubricant transferred onto the intermediate transfer belt is greater. In addition, during the idle rotation time, the cleaning device can remove the lubricant, but the toner image that functions as an abrasive is not transferred onto the intermediate transfer belt, so the effect of the removal is not great, and the amount of lubricant transferred exceeds the amount of lubricant removed. Thus, as can be seen from Figure 2, when the amount of lubricant on the intermediate transfer belt increases with embossed paper, the transferability deteriorates.

Here, the mechanism by which the transferability of embossed paper deteriorates when the amount of lubricant on the intermediate transfer belt increases will be explained with reference to Figures 3A and 3B. Figure 3A is a diagram explaining the transfer of a toner image to plain paper on the intermediate transfer belt. Also, Figure 3B is a diagram explaining the transfer of a toner image to embossed paper on the intermediate transfer belt.

A lubricant is supplied to the intermediate transfer belt from a lubricant supplying device via a photosensitive drum. The lubricant supplied to the intermediate transfer belt forms a lubricant layer on the intermediate transfer belt, as shown in Figures 3A and 3B. It is believed that the lubricant layer formed in this way deteriorates and changes in quality due to discharge products generated by the voltage applied during primary transfer and secondary transfer, causing the resistance of the lubricant layer to decrease.

When performing secondary transfer onto plain paper P0, even if the lubricant layer has a low resistance, plain paper P0 has no (small) unevenness, so the charge generated by the applied voltage does not concentrate locally. As a result, a uniform electric field is formed on plain paper P0, and the toner is easily transferred onto plain paper P0.

On the other hand, when performing secondary transfer onto embossed paper P1, if the lubricant layer has a low resistance, the charge generated by the applied voltage tends to concentrate on the convex parts because the embossed paper P1 has large projections and recesses. As a result, an electric field is formed on the convex parts of the embossed paper P1, but it is difficult to form an electric field on the recesses, and transferability to the recesses in particular deteriorates. If the lubricant layer is thick, that is, if there is a large amount of lubricant on the intermediate transfer belt, the resistance becomes lower and transferability deteriorates further.

As such, if there is a large amount of lubricant on the image carrier such as the intermediate transfer belt, the transferability of the toner to textured paper such as embossed paper is deteriorated.

The object of the present invention is to provide an image forming device that can achieve good toner transferability even on textured paper.

The image forming apparatus according to the present invention comprises:
an image carrier capable of carrying a toner image;
a lubricant supplying section for supplying a lubricant onto the image carrier;
a control unit that reduces an amount of the lubricant remaining on the image carrier before the toner image is formed on the textured paper, compared to a case in which the toner image is formed on a recording medium other than the textured paper via the image carrier;
Equipped with.
The image forming apparatus according to the present invention comprises:
an image carrier capable of carrying a toner image;
a lubricant supplying section for supplying a lubricant onto the image carrier;
a control unit that reduces an amount of the lubricant on the image carrier before the toner image is formed on the textured paper, compared to when the toner image is formed on a recording medium other than the textured paper via the image carrier;
a toner image forming unit that forms a toner image on the image carrier;
Equipped with
the control unit reduces the amount of the lubricant supplied to the image carrier in the correction operation performed when forming an image on the textured paper, compared to a correction operation for correcting performance related to image formation performed when forming an image on a recording medium other than the textured paper;
In the correcting operation, the toner image forming section forms a second toner image on the image carrier so as to fill in a gap between the first toner images required for the correcting operation.

According to the present invention, it is possible to improve the transferability of toner even on textured paper.

1 is a graph showing an evaluation of transferability using textured paper versus the contact angle of pure water on an intermediate transfer belt. 11 is a graph showing an evaluation of transferability on textured paper with or without a correction operation and the type of correction operation. 3A and 3B are diagrams illustrating the transfer of a toner image onto plain paper from an intermediate transfer belt. 4A and 4B are diagrams illustrating the transfer of a toner image onto textured paper on an intermediate transfer belt. 1 is a diagram illustrating an overall configuration of an image forming apparatus according to an embodiment of the present invention. 2 is a diagram showing a main part of a control system of the image forming apparatus according to the embodiment of the present invention; FIG. 2 shows a drum cleaning unit having a lubricant supply. 5 is a flowchart illustrating an example of a method for reducing a lubricant carried out in the image forming apparatus shown in FIG. 4 . 5 is a graph showing an evaluation of transferability ranks on textured paper with respect to the amount of toner sent to the cleaning unit of the image forming apparatus shown in FIG. 4 and the idle rotation time of the intermediate transfer belt. 13 is a graph showing an evaluation of transferability rank for uneven paper when a lubricant removal operation is performed after a correction operation. 5 is a flowchart illustrating another example (variation 2) of the method for reducing a lubricant carried out in the image forming apparatus shown in FIG. 4 . 13A and 13B are diagrams illustrating image patterns of toner images in a correction operation for adjusting the toner concentration. FIG. 13 is a diagram showing an example (image pattern 1) of a toner image in a correction operation for suppressing adhesion of lubricant; FIG. 13 is a diagram showing another example (image pattern 2) of the image pattern of the toner image in the correction operation for suppressing adhesion of the lubricant; FIG. 13 is a diagram showing another example (image pattern 3) of the image pattern of the toner image in the correction operation for suppressing adhesion of the lubricant; FIG. 13 is a diagram showing another example (image pattern 4) of the image pattern of the toner image in the correction operation for suppressing adhesion of the lubricant; 13 is a graph showing an evaluation of transferability rank on textured paper when image patterns 1 to 3 are used in correction operation A. 5 is a graph showing an evaluation of the transferability rank for textured paper with respect to the amount of toner sent to the cleaning unit of the image forming apparatus shown in FIG. 4 and the idle rotation time of the intermediate transfer belt in the correction operation A2. 13 is a graph showing an evaluation of transferability rank on textured paper when a lubricant removal operation is performed after the correction operations A2 to A4. 3A and 3B are diagrams illustrating an example of the molecular structure of a coating layer in an intermediate transfer belt having a coating layer. 1 is a graph showing the amount of _NO3 detected initially and after continuously processing 50,000 sheets in an intermediate transfer belt having a coating layer.

The image forming device according to the embodiment of the present invention will be described in detail below with reference to the drawings.

Figure 4 is a diagram showing the overall configuration of the image forming apparatus 1 according to this embodiment. Figure 5 is a diagram showing the main parts of the control system of the image forming apparatus 1 according to this embodiment. Note that the image forming apparatus 1 is an example of this embodiment, and its configuration and specifications are not limited to the following description and can be modified as appropriate.

As shown in FIG. 4, the image forming device 1 is a color image forming device of the intermediate transfer type that utilizes electrophotographic process technology. That is, the image forming device 1 forms an image by primarily transferring each of the CMYK color toner images formed on the photosensitive member to an intermediate transfer body, superimposing the four color toner images on the intermediate transfer body, and then secondary transferring the images onto a recording medium, namely paper. Note that CMYK stands for C (cyan), M (magenta), Y (yellow), and K (black).

The image forming device 1 also uses a tandem system in which photoconductors corresponding to the four colors CMYK are arranged in series in the running direction of the intermediate transfer body, and each color toner image is transferred sequentially to the intermediate transfer body in a single step.

The image forming device 1 shown in Figures 4 and 5 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper conveying unit 50, a fixing unit 60, and a control unit 70.

The control unit 70 includes a CPU (Central Processing Unit) 71, a ROM (Read Only Memory) 72, and a RAM (Random Access Memory) 73. The CPU 71 reads a program corresponding to the processing contents from the ROM 72, loads it into the RAM 73, and centrally controls the operation of each block of the image forming device 1 in cooperation with the loaded program. At this time, various data such as a LUT (Look Up Table) stored in the memory unit 82 is referenced. The memory unit 82 is composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 70 transmits and receives various data to and from an external device (e.g., a personal computer) connected to a communication network such as a LAN (Local Area Network) or a WAN (Wide Area Network) via the communication unit 81. The control unit 70 receives, for example, image data transmitted from an external device, and forms an image on paper based on this image data (input image data). The communication unit 81 is, for example, configured with a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeder 11, also known as an ADF (Auto Document Feeder), and a document image scanning device 12 (scanner).

The automatic document feeder 11 transports the document D placed on the document tray using a transport mechanism and sends it to the document image scanning device 12. The automatic document feeder 11 can continuously read the images (including both sides) of multiple documents D placed on the document tray all at once.

The document image scanning device 12 optically scans the document transported from the automatic document feeder 11 onto the contact glass or the document placed on the contact glass, and forms an image of the reflected light from the document on a CCD (Charge Coupled Device) sensor 12a to read the document image. The image reading unit 10 generates input image data based on the results of the reading by the document image scanning device 12. This input image data is subjected to a predetermined image processing in the image processing unit 30.

The operation display unit 20 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, image status displays, and the operating status of each function according to a display control signal input from the control unit 70. The operation unit 22 has various operation keys such as a numeric keypad and a start key, accepts various input operations by the user, and outputs operation signals to the control unit 70.

The image processing unit 30 includes a circuit that performs image processing on input image data according to initial settings or user settings. The image forming unit 40 is controlled based on the image data that has been subjected to image processing.

The image forming section 40 includes image forming units 41Y, 41M, 41C, and 41K, and an intermediate transfer unit 42 for forming images using the color toners of the Y, M, C, and K components based on image data from the image processing section 30.

The image forming units 41Y, 41M, 41C, and 41K for the Y, M, C, and K components have the same configuration. Therefore, in FIG. 4, only the components of the image forming unit 41Y for the Y component are labeled, and the components of the other image forming units 41M, 41C, and 41K are not labeled.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photosensitive drum 413 (image carrier), a charging device 414, a drum cleaning unit (hereinafter, cleaning unit) 415, etc.

The exposure device 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with laser light corresponding to an image of each color component. Positive charges are generated in the charge generation layer of the photoconductor drum 413 by irradiation with the laser light, and when the charges are transported to the surface of the charge transport layer, the surface charge (negative charge) of the photoconductor drum 413 is neutralized. As a result, an electrostatic latent image of each color component is formed on the surface of the photoconductor drum 413 due to the potential difference with the surroundings.

The developing device 412 is, for example, a two-component developing device having a developing sleeve 412A, and by depositing toner of each color component from the developing sleeve 412A onto the surface of the photoconductor drum 413, the electrostatic latent image is visualized to form a toner image.

The photoconductor drum 413 includes, for example, an aluminum conductive cylinder (aluminum tube), an undercoat layer (UCL), a charge generation layer (CGL), a charge transport layer (CTL), etc. This photoconductor drum 413 is a photoconductor having photoconductivity formed by sequentially laminating an undercoat layer, a charge generation layer, and a charge transport layer on the circumferential surface of a conductive cylinder, and is, for example, a negatively charged organic photoconductor (OPC). The control unit 70 controls the drive current supplied to the drive motor (not shown) of the photoconductor drum 413, so that the photoconductor drum 413 rotates at a constant peripheral speed (linear speed).

The charging device 414 uniformly charges the surface of the photoconductive photoconductor drum 413 to a negative polarity.

The cleaning unit 415 will be described with reference to FIG. 6. FIG. 6 is a diagram showing the cleaning unit 415 having a lubricant supply unit 450. The cleaning unit 415 includes a drum cleaning blade (hereinafter, cleaning blade) 416, a lubricant supply unit 450, and the like. These are attached to a support frame 415a.

The cleaning blade 416 (cleaning unit) is in sliding contact with the surface of the photosensitive drum 413, and removes residual toner remaining on the surface of the photosensitive drum 413 after the primary transfer. The cleaning blade 416 is a flat sheet made of an elastic material such as urethane rubber, and has a width approximately equal to the width of the photosensitive drum 413 in the axial direction (main scanning direction). The cleaning blade 416 is configured in a counter type so that its tip (edge) abuts against the rotation direction R1 of the photosensitive drum 413. Specifically, it is arranged to slide in contact with the photosensitive drum 413 at a predetermined abutment angle and penetration amount from a counter direction (the direction in which the tip of the cleaning blade 416 is stretched when the photosensitive drum 413 rotates) with respect to the rotation direction R1 of the photosensitive drum 413.

The lubricant supply unit 450 includes a brush 451, a lubricant 452, a pressing member 453, and a supporting plate 454. The lubricant 452 is formed by solidifying the lubricant. The brush 451 and the lubricant 452 are supported by the supporting plate 454 and are fixed to the supporting frame 415a via the pressing member 453. The pressing member 453 is, for example, a compression spring, and presses the lubricant 452 toward the brush 451 with a predetermined pressing load in order to keep the lubricant 452 in contact with the brush 451. The width of the lubricant 452 is narrower than the width of the cleaning blade 416. The lubricant 452 has, for example, a pencil hardness equivalent to F to HB. The lubricant used for the lubricant 452 is, for example, zinc stearate (ZnSt).

Brush 451 has the role of supplying lubricant 452 onto photoconductor drum 413. Brush 451 is, for example, a roller-shaped brush in which a base cloth with fibers such as polyester woven therein is wound around a core metal, and has a width approximately equal to the axial width of photoconductor drum 413. Brush 451 is arranged so as to come into contact with the surface of lubricant 452 and the surface of photoconductor drum 413, and rotates in rotation direction R2 opposite to rotation direction R1 of photoconductor drum 413 to supply lubricant onto photoconductor drum 413.

As shown in FIG. 4, the intermediate transfer unit 42 includes an intermediate transfer belt 421, a plurality of support rollers 423, a secondary transfer roller 424, a main cleaner 426, a sub-cleaner 427, etc. The plurality of support rollers 423 include rollers such as a drive roller 423A and a backup roller 423B.

The intermediate transfer belt 421 (image carrier) is stretched in a loop around multiple support rollers 423, and the intermediate transfer belt 421 runs at a constant speed in the direction of arrow A as the drive roller 423A rotates. The primary transfer roller 422 presses the intermediate transfer belt 421 against the photosensitive drum 413, thereby transferring the toner image from the photosensitive drum 413 to the intermediate transfer belt 421. The secondary transfer roller 424 is pressed against the backup roller 423B with the intermediate transfer belt 421 in between, thereby transferring the toner image from the intermediate transfer belt 421 to the paper P. The paper P to which the toner image has been transferred is transported toward the fixing unit 60. Instead of the secondary transfer roller 424, a belt-type secondary transfer unit in which the secondary transfer belt is stretched in a loop around multiple support rollers may be used.

Here, the intermediate transfer belt 421 has at least two layers, a base layer and a surface layer disposed on the base layer. For example, polyimide (PI) resin is used for the base layer. The base layer may be a single layer or a multi-layer structure. For example, a material containing silicon dioxide (SiO ₂ ) as a main component is used for the surface layer. In other words, the intermediate transfer belt 421 is configured by applying a coating layer containing glass (SiO ₂ ) as a main component. Furthermore, the surface roughness of the intermediate transfer belt 421 is ten-point average roughness Rzjis=0.75 μm.

The main cleaner 426 (cleaning unit) is disposed upstream of the sub-cleaner 427 in the rotation direction A of the intermediate transfer belt 421. The main cleaner 426 is equipped with a cleaning blade and a support frame that remove foreign matter by sliding against the surface of the intermediate transfer belt 421 that rotates in the rotation direction A.

The cleaning blade of the main cleaner 426 is a member that removes toner, lubricants, and the like that have adhered to the surface of the intermediate transfer belt 421. The cleaning blade has its tip (edge) abutted against the surface of the intermediate transfer belt 421 in the counter direction to the rotation direction A of the intermediate transfer belt 421. The material of the cleaning blade is, for example, urethane rubber, but any other elastic material may be used.

The sub-cleaner 427 (cleaning unit) is disposed adjacent to the main cleaner 426 on the downstream side of the rotation direction A of the intermediate transfer belt 421. The sub-cleaner 427 is downstream of the main cleaner 426 and includes a scraper and a support frame that slides against the surface of the intermediate transfer belt 421 to remove foreign matter.

The scraper of the sub-cleaner 427 is a member that removes toner, lubricant, and the like that has adhered to the surface of the intermediate transfer belt 421 and that has not been completely removed by the main cleaner 426. This scraper abuts the tip (edge) of the scraper against the surface of the intermediate transfer belt 421 in the counter direction to the rotation direction A of the intermediate transfer belt 421. The material of the scraper is, for example, a metal such as stainless steel, but any other material may be used.

The paper transport section 50 includes a paper feed section 51, a paper discharge section 52, and a transport path section 53. The three paper feed trays 51a to 51c that make up the paper feed section 51 store paper P that has been identified based on basis weight, size, etc., by pre-set type. The transport path section 53 has multiple transport roller pairs, such as a registration roller pair 53a.

The paper P stored in the paper feed trays 51a to 51c is sent out one by one from the top and transported to the image forming unit 40 by the transport path unit 53. At this time, the inclination of the fed paper P is corrected and the transport timing is adjusted by the registration roller unit in which the registration roller pair 53a is arranged. Then, the paper P on which an image has been formed through the image forming unit 40 and the fixing unit 60 is discharged outside the machine by the paper discharge unit 52 equipped with the paper discharge roller 52a.

The fixing unit 60 heats and presses the transported paper P in a fixing nip, fixing the toner image to the paper P. The fixing unit 60 includes a fixing belt 61, a heating roller 62, a fixing roller 63, and a pressure roller 64. The fixing belt 61 is stretched between the heating roller 62 and the fixing roller 63. The pressure roller 64 forms a fixing nip between the fixing belt 61 and the paper P to sandwich and transport it.

However, in the image forming apparatus 1 having the above-mentioned lubricant supply unit 450, when forming an image on uneven paper such as embossed paper, it has been found that if there is a large amount of lubricant on the intermediate transfer belt 421, the transferability of the toner image onto the uneven paper deteriorates.

In this embodiment, the image forming device 1 includes an intermediate transfer belt 421 capable of carrying a toner image, and a lubricant supply unit 450 that supplies lubricant onto the intermediate transfer belt 421. The image forming device 1 also includes a control unit 70 that reduces the amount of lubricant on the intermediate transfer belt 421 before the toner image is formed on the textured paper via the intermediate transfer belt 421, compared to when a toner image is formed on a recording medium other than textured paper.

When forming an image on textured paper using the image forming device 1, the control of the control unit 70 to reduce the amount of lubricant on the intermediate transfer belt 421 will be described with reference to FIG. 7. FIG. 7 is a flow chart that describes an example of a method for reducing lubricant implemented by the image forming device 1.

(Step S11)
In the image forming apparatus 1, when an operation command such as an image forming operation or a correction operation is given, the control unit 70 checks whether or not textured paper is to be used. If textured paper is to be used (YES), the process proceeds to step S12, and if textured paper is not to be used (NO), the process proceeds to step S16. The correction operation is an operation for correcting the performance related to image formation in the image forming apparatus 1.

The operation command for the image forming operation is issued, for example, when the user presses the start button on the operation display unit 20. The operation command for the correction operation is issued, for example, when the user performs a start operation on the operation display unit 20. In addition, the operation command for the correction operation is issued before the start of the image forming operation or during non-image formation, including between sheets during the image forming operation, when the control unit 70 determines that the conditions for performing the correction operation are met.

The control unit 70 also checks information about the paper on which an image is to be formed and determines whether or not to use textured paper. For example, the user can input or select information about the type of paper (paper information) set in the paper feed trays 51a to 51c on the paper setting screen (selection section) displayed on the display unit 21 of the operation display unit 20. The control unit 70 checks the paper feed tray currently being used, and if the paper information for that paper feed tray is textured paper (e.g., embossed paper), determines that textured paper should be used.

In addition, if the paper information for at least one of the paper feed trays 51a to 51c is textured paper, the control unit 70 may determine that an image forming operation using textured paper is likely to be performed and may determine that textured paper will be used. In other words, the control unit 70 may determine that textured paper will be used just because there is a possibility that an image forming operation using textured paper will be performed. Conversely, if the paper information for any of the paper feed trays 51a to 51c is not textured paper, the control unit 70 may determine that an image forming operation using paper other than textured paper will be performed and may determine that textured paper will not be used.

Instead of inputting or selecting the paper information described above, the smoothness of the paper may be input. Also, a detector for detecting the physical properties of the paper may be provided, for example, in the transport path section 53, and the control section 70 may determine the use of textured paper based on the detection results of the detector.

(Step S12)
The control unit 70 checks whether the operation command is a correction operation. If it is a correction operation (YES), the process proceeds to step S14, and if it is not a correction operation (NO), that is, if it is an image forming operation, the process proceeds to step S13.

(Step S13)
The lubricant on the intermediate transfer belt 421, which is an image carrier, is removed. To explain this in detail with reference to Fig. 4, the intermediate transfer belt 421 is rotated idly, and the intermediate transfer belt 421 passing through the cleaning blade of the main cleaner 426 and the scraper of the sub-cleaner 427 is polished to remove the lubricant adhering to the intermediate transfer belt 421.

When the intermediate transfer belt 421 rotates idly, it abuts against the cleaning blade of the main cleaner 426 and the scraper of the sub-cleaner 427, but does not abut against the photoconductor drum 413 or the secondary transfer roller 424, and is spaced apart from them. In other words, the intermediate transfer belt 421 rotates idly with respect to the photoconductor drum 413 and the secondary transfer roller 424 other than the main cleaner 426 and the sub-cleaner 427. In this way, during the idling rotation in the lubricant removal operation, the intermediate transfer belt 421 does not abut against the photoconductor drum 413. On the other hand, during the idling rotation in the correction operation, the intermediate transfer belt 421 abuts against the photoconductor drum 413. Therefore, hereinafter, the idling rotation during the lubricant removal operation is referred to as removal-time free rotation.

In this way, when performing an image formation operation on textured paper, a lubricant removal operation is performed to remove the lubricant adhering to the intermediate transfer belt 421 before starting the image formation operation. Note that, although the lubricant removal operation is performed before the start of the image formation operation here, in the case of a correction operation performed during the image formation operation, if the image formation operation is temporarily interrupted due to mechanical operation or the like, the lubricant removal operation may be performed before resuming it. Also, during the image formation operation, the image formation operation may be periodically interrupted and the lubricant removal operation may be performed before resuming it.

The lubricant removal operation is performed before starting the image formation operation on textured paper, but even if it is performed before starting the image formation operation on paper other than textured paper, for example plain paper, it does not cause any problems with the image formation operation on plain paper. In other words, as explained in step S11, there is only a possibility that an image formation operation using textured paper will be performed, and it may be determined that textured paper will be used and the lubricant removal operation may be performed. However, taking into account the time required for the lubricant removal operation, it is preferable not to perform the lubricant removal operation in the case of paper other than textured paper.

(Step S14)
In step S12, if the operation command is a correction operation, the image forming apparatus 1 performs the correction operation, but after the correction operation, a lubricant removal operation is performed, or the correction operation is performed by reducing the amount of lubricant supplied.

If a lubricant removal operation is performed after the correction operation, the lubricant is removed by the main cleaner 426 and sub-cleaner 427 as described in step S13.

When performing a correction operation by reducing the amount of lubricant supplied, the lubricant is less likely to adhere to the intermediate transfer belt 421 during the correction operation than in the case of paper other than textured paper (e.g., plain paper).

Referring to FIG. 6, by stopping the supply of lubricant to the photoconductor drum 413 by the lubricant supply unit 450, lubricant is not supplied from the photoconductor drum 413 to the intermediate transfer belt 421, and the lubricant is less likely to adhere to the intermediate transfer belt 421. For example, as described in Variation 4 below, the lubricant supply unit 450 may separate the brush 451 from the photoconductor drum 413. Furthermore, as described in Variation 5 below, the rotation of the brush 451 may be stopped.

(Step S15)
After the correction operation, the control unit 70 checks whether the image forming operation is to be continued or not. If the image forming operation is to be continued (YES), the process proceeds to step S16, and if not (NO), the process ends.

(Step S16)
The control unit 70 performs an image forming operation in the image forming apparatus 1. In the case of plain paper, the image forming operation is performed without reducing the amount of lubricant on the intermediate transfer belt 421 according to the above-mentioned procedure. On the other hand, in the case of textured paper, the lubricant on the intermediate transfer belt 421 is reduced according to the above-mentioned procedure, and the image forming operation is performed.

As described above, the image forming apparatus 1 of this embodiment includes an intermediate transfer belt 421 capable of carrying a toner image, and a lubricant supply unit 450 that supplies lubricant onto the intermediate transfer belt 421. The image forming apparatus 1 also includes a control unit 70 that reduces the amount of lubricant on the intermediate transfer belt 421 before a toner image is formed on the textured paper via the intermediate transfer belt 421, compared to when a toner image is formed on a recording medium other than textured paper.

According to the image forming device 1 of this embodiment configured in this way, when forming an image on textured paper, the amount of lubricant on the intermediate transfer belt 421 is reduced, so that the toner can be transferred well even on textured paper.

[Modification 1]
In this modification, the configuration of image forming apparatus 1 is as described in the above embodiment. Also, in this modification, the method of reducing lubricant performed by image forming apparatus 1 is basically the same as in the above embodiment (see FIG. 7). However, this modification differs from the above embodiment in that toner is sent to main cleaner 426 and sub-cleaner 427 in the lubricant removal operation.

In the lubricant removal operation, as described above, the main cleaner 426 and the sub-cleaner 427 are brought into contact with the intermediate transfer belt 421, and the intermediate transfer belt 421 is rotated for removal. At this time, if toner is present on the intermediate transfer belt 421, the toner can be sent to the main cleaner 426 and the sub-cleaner 427. When the toner is sent to the main cleaner 426 and the sub-cleaner 427, the toner acts as an abrasive, and the effect of removing the lubricant from the intermediate transfer belt 421 can be improved.

For example, before the intermediate transfer belt 421 is rotated for removal, a toner image may be transferred from the photosensitive drum 413 to the intermediate transfer belt 421, thereby supplying toner onto the intermediate transfer belt 421. Also, a separate device may be provided for supplying toner onto the intermediate transfer belt 421.

When the three types of correction operations A to C shown in FIG. 2 are performed in the image forming device 1, the transferability rank when each of the correction operations A to C is performed is as shown in FIG. 2.

More specifically, the transferability rank is defined as follows: This definition is the same in Figs. 1 and 2 and Figs. 8, 9, and 16 to 18 described later.
Rank 5: No problem Rank 4: Slight transfer failure, but fully acceptable Rank 3: Some areas of transfer failure, but acceptable Rank 2: Wide area of transfer failure, NG level Rank 1: Fully defective transfer

As explained in FIG. 2, the idle rotation times a to c of the correction operations A to C are a>b>c, and in the correction operation A, in which the idle rotation time a during which no image formation is performed is the longest, the transferability rank deteriorates to the NG level.

After performing the above-mentioned correction operation A, when performing the lubricant removal operation, the conditions of the toner feed amount fed to the main cleaner 426 and the sub-cleaner 427 and the idling time of the removal space rotation of the intermediate transfer belt 421 were changed, and the transferability rank was evaluated. Here, under each condition, the toner was fed to the main cleaner 426 and the sub-cleaner 427 first, and then the intermediate transfer belt 421 was rotated for the removal space rotation. FIG. 8 is a graph showing the transferability rank of the textured paper against the toner feed amount and the idling time of the removal space rotation. In this evaluation, the textured paper, embossed paper, was a product name of Lezac 66 (registered trademark), white, and had a basis weight of 302 g/ ^m2 , and a full-surface solid image formed with two layers (blue) was used for the image evaluation.

As shown in FIG. 8, the transferability rank immediately after performing correction operation A was "1.5" (0g, 0 second point in FIG. 8). By performing a lubricant removal operation with a changed toner feed amount and idling time of the removal space rotation after performing such correction operation A, the transferability rank improves as shown in FIG. 8. For example, even if the toner feed amount is 0g, if the idling time of the removal space rotation is set to 60 seconds, the transferability rank improves to "3.0" (0g, 60 second point in FIG. 8). Also, if the toner feed amount is 9g and the idling time of the removal space rotation is set to 80 seconds, the transferability rank improves to "4.0" (9g, 80 second point in FIG. 8)

Here, the transferability rank 3 is set as the acceptable level. Note that this acceptable level can be changed as appropriate depending on the configuration of the image forming device 1 and the required image quality. In FIG. 8, the line T1 of the transferability rank 3 is shown by a dotted line, and the conditions in the area above the line T1 are the acceptable level. In FIG. 8, in order to achieve a transferability rank of 3.0, for example, when the conditions for the least amount of toner consumption and the shortest idle rotation time of the removal space rotation are set as the lubricant removal operation, the toner feed amount may be set to 2 g and the idle rotation time of the removal space rotation may be set to 20 seconds. Note that the setting of the conditions for this lubricant removal operation can be changed as appropriate depending on whether to prioritize suppressing toner consumption, shortening the idle rotation time of the removal space rotation, or improving the transferability rank.

In this way, the conditions for the lubricant removal operation are set. Then, after performing the correction operations A to C shown in FIG. 2, the lubricant removal operation is performed under the conditions of a toner feed amount of 2 g and an idle rotation time of 20 seconds during removal, and these are called correction operations A1 to C1, respectively, and the transferability rank is evaluated. FIG. 9 is a graph that evaluates the transferability rank on textured paper when the above-mentioned lubricant removal operation is performed after correction operations A to C.

As shown in FIG. 9, correction operation A1, in which the above-mentioned lubricant removal operation is performed after correction operation A, has an improved transferability rank of "3.0". Furthermore, correction operation B1, in which the above-mentioned lubricant removal operation is performed after correction operation B, has an improved transferability rank of "3.5", and correction operation C1, in which the above-mentioned lubricant removal operation is performed after correction operation C, has an improved transferability rank of "4.0".

As described above, the image forming apparatus 1 of this modified example is equipped with a toner supply unit that supplies toner to the main cleaner 426 and the sub-cleaner 427 and has the main cleaner 426 and the sub-cleaner 427 clean the lubricant together with the toner.

According to the image forming apparatus 1 of this embodiment configured as described above, after the correction operation is performed, the lubricant removal operation is performed in which toner is sent to the main cleaner 426 and the sub-cleaner 427 and the intermediate transfer belt 421 rotates during removal. This makes it possible to improve the effect of removing the lubricant on the intermediate transfer belt 421 by using toner that acts as an abrasive. As a result, it is possible to improve the transferability to textured paper.

In this case, the correction operation is performed by the user starting the correction operation, as in the above embodiment. In addition, if the conditions for performing the correction operation are met, the correction operation is performed before the start of the image formation operation or during non-image formation, including between sheets during the image formation operation.

In this example, the lubricant removal operation is performed after the correction operation, but the lubricant removal operation may be performed during the correction operation or may be performed multiple times. In either case, it is preferable to perform the lubricant removal operation after an operation that is most likely to transfer the lubricant onto the intermediate transfer belt 421.

In addition, here, the lubricant removal operation is performed for all of correction operations A to C. However, in order to reduce toner consumption and the idle rotation time during removal, the lubricant removal operation may be performed for correction operation A, which has a transferability rank of "1.5," below the acceptable level.

The main cleaner 426 may also be configured with a space S for storing the toner removed by the cleaning blade, as shown in FIG. 4. In this case, the toner stored in the space S comes into surface contact with the intermediate transfer belt 421, making it possible to more effectively polish off the lubricant.

In addition, the contact conditions of the cleaning blade of the main cleaner 426 and the scraper of the sub-cleaner 427 that remove the lubricant may be different during the lubricant removal operation and during the image formation operation. For example, during the lubricant removal operation, the contact conditions such as the contact force of the cleaning blade or scraper, the contact angle, and the movement speed of the intermediate transfer belt 421 may be changed to conditions that make it easier to remove the lubricant. Furthermore, a contact member that contacts the intermediate transfer belt 421 to remove the lubricant may be provided in addition to the cleaning blade of the main cleaner 426 and the scraper of the sub-cleaner 427.

[Modification 2]
In this modification, the configuration of the image forming apparatus 1 is as described in the above embodiment. Also, in this modification, the method of reducing lubricant performed by the image forming apparatus 1 is basically the same as that of the above embodiment (see FIG. 7). However, as can be seen from a comparison between FIG. 7 and FIG. 10, this modification differs from the above embodiment in that step S21 is added to the lubricant removal operation. Here, FIG. 10 is a flowchart for explaining another example of the method of reducing lubricant performed by the image forming apparatus 1.

The flowchart in FIG. 10 is the same as the flowchart in FIG. 7 described in the above embodiment, except that step S21 has been added between steps S12 and S13. Therefore, steps that overlap with the flowchart in FIG. 7 will be explained briefly here.

(Step S11)
Step S11 is as described with reference to FIG.

(Step S12)
The control unit 70 checks whether the operation command is a correction operation. If it is a correction operation (YES), the process proceeds to step S14, and if it is not a correction operation (NO), that is, if it is an image forming operation, the process proceeds to step S21.

(Step S21)
The control unit 70 checks whether a correction operation with a long idling time has been performed recently. If a correction operation with a long idling time has been performed recently (YES), the process proceeds to step S13, and if a correction operation with a long idling time has not been performed recently (NO), the process proceeds to step S16.

As explained in FIG. 2, when correction operations B and C, which have a short idling time, are performed, the time required for forming the toner image on the intermediate transfer belt is long, and the amount of lubricant on the intermediate transfer belt 421 decreases. On the other hand, when correction operation A, which has a long idling time, is performed, a large amount of lubricant remains on the intermediate transfer belt 421. Therefore, in step S21, if correction operation A, which has a long idling time, has been performed recently, a large amount of lubricant remains on the intermediate transfer belt 421, and in that case, the process proceeds to step 13.

In this way, if correction operation A, which has a long idling time, is performed immediately before the image formation operation and a large amount of lubricant remains on the intermediate transfer belt 421, the process proceeds to step S13 and a lubricant removal operation is performed. If correction operation A, which has a long idling time, is performed, a flag may be set, and in step S21, a determination may be made as to whether to proceed to step S13 or step S16 depending on whether the flag is set. Also, if a large amount of lubricant remains on the intermediate transfer belt 421 for reasons other than correction operation A, the flag may be set.

(Steps S13 to S16)
Steps S13 to S16 are as described with reference to FIG.

As described above, the image forming device 1 of this modified example is configured to perform a lubricant removal operation if a large amount of lubricant remains on the intermediate transfer belt 421.

According to the image forming device 1 of this modified example configured in this manner, if a large amount of lubricant remains on the intermediate transfer belt 421, a lubricant removal operation can be performed to reduce the amount of lubricant on the intermediate transfer belt 421. As a result, the transferability to textured paper can be improved.

[Modification 3]
In this modification, the configuration of the image forming apparatus 1 is as described in the above embodiment. Also, in this modification, the method of reducing the amount of lubricant performed by the image forming apparatus 1 is basically the same as that of the above embodiment (see FIG. 7). However, in this modification, the correction operation differs from the above embodiment in that a toner image for suppressing the amount of lubricant (second toner image) is formed on the intermediate transfer belt 421 in addition to a correction toner image (first toner image) necessary for the correction operation.

In this modified example, the image pattern of the toner image used during the correction operation is changed to prevent the adhesion of lubricant onto the intermediate transfer belt 421 during the correction operation.

First, the correction toner image required for the correction operation will be described with reference to FIG. 11. FIG. 11 is a diagram showing the image pattern of the toner image in the correction operation for adjusting the toner concentration.

The correction operation of the image forming device 1 typically involves ATVC (Active Transfer Voltage Control), toner concentration adjustment, potential correction on the photoconductor drum 413, color registration correction, etc.

The toner density adjustment and color registration correction are performed based on the detection result of the toner image formed on the intermediate transfer belt 421 detected by the density sensor 461 (see FIG. 4). The density sensor 461 has, for example, an irradiation section that irradiates light toward the intermediate transfer belt 421 and a light receiving section that receives reflected light from the intermediate transfer belt 421, and the detection result of the reflected light at the light receiving section is used for the above adjustment and correction. As shown in FIG. 4, the density sensor 461 is disposed downstream of the photoconductor drum 413 in the rotation direction A. Also, as shown in FIG. 11, multiple density sensors (two in FIG. 11 as an example) are disposed in the width direction (main operation direction) of the intermediate transfer belt 421.

Therefore, toner images Ty01-Ty03, Tc01-Tc03, Tm01-Tm03, and Tb01-Tb03 required for toner concentration adjustment and color registration correction are formed at positions on the intermediate transfer belt 421 that pass the density sensor 461. In FIG. 11, Wmax is the maximum image width of the intermediate transfer belt 421. In FIG. 11 and FIGS. 12-15 described below, the symbol Ty indicates a yellow toner image, the symbol Tc indicates a cyan toner image, the symbol Tm indicates a magenta toner image, and the symbol Tb indicates a black toner image.

The areas of the toner images Ty01 to Ty03, Tc01 to Tc03, Tm01 to Tm03, and Tb01 to Tb03 shown in FIG. 11 are kept to a minimum to prevent unnecessary toner consumption. As a result, there are many areas where no toner is present, and the lubricant is likely to adhere to the intermediate transfer belt 421.

Therefore, in this modified example, in addition to the toner image required for the correction operation, a toner image for suppressing lubricant is formed on the intermediate transfer belt 421 to suppress the transfer of lubricant to the intermediate transfer belt 421.

For example, FIG. 12 shows an example of a toner image pattern (image pattern 1) during a correction operation to suppress lubricant adhesion.

In FIG. 12, in addition to the toner images Ty01 to Ty03, Tc01 to Tc03, Tm01 to Tm03, and Tb01 to Tb03 shown in FIG. 11, a toner image T11 for suppressing lubricant is formed on the intermediate transfer belt 421.

As shown in FIG. 12, toner image T11 is formed on intermediate transfer belt 421 so as to fill in the spaces between toner images Ty01-Ty03, Tc01-Tc03, Tm01-Tm03, and Tb01-Tb03, that is, to fill in the areas where no toner exists. In this way, toner image T11 is formed in addition to toner images Ty01-Ty03, Tc01-Tc03, Tm01-Tm03, and Tb01-Tb03 so as to cover the lubricant adhering to photoconductor drum 413. This makes it possible to prevent the transfer of lubricant from photoconductor drum 413 to intermediate transfer belt 421, and to prevent the lubricant from adhering to intermediate transfer belt 421. In addition, in the areas where the toner image is formed, the toner image is transferred from photoconductor drum 413 to intermediate transfer belt 421 instead of the lubricant. Therefore, toner that acts as an abrasive for the lubricant can be supplied to the intermediate transfer belt 421, improving the effect of removing the lubricant from the intermediate transfer belt 421.

The toner image T11 may be a halftone image. Also, if the areas where no toner is present can be filled without changing the toner images Ty01-Ty03, Tc01-Tc03, Tm01-Tm03, and Tb01-Tb03, the toner image T11 may have a pattern other than the pattern shown in FIG. 12.

Figure 13 shows another example of a toner image pattern (image pattern 2) during the correction operation to suppress lubricant adhesion.

In FIG. 13, toner images Ty11-Ty13, Tc11-Tc13, Tm11-Tm13, and Tb11-Tb13 are formed on the intermediate transfer belt 421. In other words, the toner images Ty01-Ty03, Tc01-Tc03, Tm01-Tm03, and Tb01-Tb03 shown in FIG. 11 are not changed, but are extended in the main operation direction of the intermediate transfer belt 421.

As shown in FIG. 13, toner images Ty11-Ty13, Tc11-Tc13, Tm11-Tm13, and Tb11-Tb13 are formed on the intermediate transfer belt 421 so that there are fewer areas where there is no toner. This makes it possible to prevent the lubricant from adhering to the intermediate transfer belt 421.

As shown in FIG. 13, it is not necessary to fill the intermediate transfer belt 421 with a toner image, but it is preferable to fill at least one area entirely in the main scanning direction with a toner image. This is because if one area is entirely filled in the main scanning direction with a toner image, even if there is an area in the sub-scanning direction where there is no toner image, there will be an area in the main scanning direction where toner is sent to that area. Lubricant that adheres to the intermediate transfer belt 421 from the area where there is no toner image can be removed by being polished by the toner sent from the area where there is a toner image.

On the other hand, even if the entire sub-scanning direction in one area is filled with toner images, if there is an area in the main scanning direction where there is no toner image, there may be no other area in the main scanning direction to send toner to that area. In that case, the lubricant that has adhered to the intermediate transfer belt 421 from the area where there is no toner image will be cleaned without the abrasive toner being sent in, and there is a possibility that the lubricant will remain. Thus, from the perspective of lubricant removal by toner, it is acceptable for there to be gaps in the toner image in the sub-scanning direction, but it is better for there to be no gaps in the toner image in the main scanning direction.

Figure 14 shows another example of a toner image pattern (image pattern 3) during correction operation to suppress lubricant adhesion.

In FIG. 14, in addition to the toner images Ty02-Ty03, Tc01-Tc03, Tm02-Tm03, and Tb01-Tb03 shown in FIG. 11, toner images Ty11, Tm11, T21, and T22 are formed on the intermediate transfer belt 421. The toner images Ty11 and Tm11 are obtained by extending the toner images Ty01 and Tm01 shown in FIG. 11 in the main operation direction of the intermediate transfer belt 421 without changing the portions of the toner images. In addition, the toner images T21 and T22 are halftone, and are obtained by extending the toner images Tc01 and Tb01 shown in FIG. 11 in the main operation direction of the intermediate transfer belt 421.

As shown in FIG. 14, it is not necessary to fill the intermediate transfer belt 421 with a toner image, but it is preferable to fill at least one area entirely in the main scanning direction with a toner image. The reason for this is as explained in FIG. 13.

In addition, in FIG. 14, as shown by toner images Ty11 and Tm11, the solid image may be extended in the main operation direction of the intermediate transfer belt 421. Also, as shown by toner images T21 and T22, the solid image may be extended in the main operation direction of the intermediate transfer belt 421 in halftone from toner images Tc01 and Tb01. By making the toner images T21 and T22 halftone, the amount of toner consumed can be reduced.

Figure 15 shows another example of a toner image pattern (image pattern 4) during correction operation to suppress lubricant adhesion.

Depending on the correction operation, there is an operation in which a toner image should not be present, such as potential correction on the photosensitive drum 413. The potential correction on the photosensitive drum 413 is performed based on the detection result of a potential sensor (not shown) that is provided opposite the surface of the photosensitive drum 413 and detects the surface potential of the photosensitive drum 413. In the case of such correction, as shown in FIG. 15, toner images Ty21, Tm21, Tc21, and Tb21 are formed on the intermediate transfer belt 421 except for areas f1 to f4 on the intermediate transfer belt 421 that correspond to the area on the photosensitive drum 413 detected by the potential sensor. In other words, toner images Ty21, Tm21, Tc21, and Tb21 are formed on the intermediate transfer belt 421 in the area not detected by the potential sensor. In FIG. 15, the toner images Ty21, Tm21, Tc21, and Tb21 are arranged between areas f1 and f2 and areas f3 and f4 in the sub-scanning direction, and are formed in a band shape extending in the main scanning direction. Halftone toner images T31 to T33 may also be formed to sandwich areas f3 and f4.

The toner images Ty21, Tm21, Tc21, and Tb21 are changed as appropriate depending on the content of the correction operation, but in FIG. 15 as well, the entire main scanning direction is filled with toner images, and the reason for this is as explained in FIG. 13.

Note that Figures 12 to 15 show examples of image patterns for forming toner images for removing lubricant, but the color and amount of toner adhesion can be changed appropriately for each toner image.

However, in a correction operation that includes image density correction, if too much toner is consumed, the state of the materials may change during the correction operation, and the image density correction result may be abnormal. For this reason, a toner image is formed in a limited area. Also, toner consumption is suppressed by forming a toner image using a halftone that suppresses the amount of toner adhesion. When using a toner image that suppresses toner consumption in this way, it may be used in combination with the lubricant removal operation shown in Modification 1, as described in Modification 6 below. In this case, even if the amount of toner sent in the lubricant removal operation shown in Modification 1 and the idle rotation time of the removal time free rotation are reduced, transferability equivalent to that of Modification 1 can be obtained.

Here, correction operation A was set as the correction operation to be performed by image forming apparatus 1 shown in FIG. 4, and the above image patterns 1 to 3 were set as the image patterns of the toner images to be used in correction operation A, and new correction operations A2 to A4 were performed. Correction operation A2 is correction operation A that uses image pattern 1, correction operation A3 is correction operation A that uses image pattern 2, and correction operation A4 is correction operation A that uses image pattern 3.

Figure 16 is a graph evaluating the transferability rank on textured paper when image patterns 1 to 3 are used in correction operation A. As shown in Figure 16, the transferability ranks of correction operations A2 to A4 are all improved over the transferability rank of correction operation A. Correction operation A3, which has the highest transferability rank among correction operations A2 to A4, is image pattern 2, which has the greatest amount of toner adhesion. From this result, if transferability rank 3 is considered an acceptable level, image patterns 2 or 3 are good to use in correction operation A.

In this manner, in this modified example, in addition to the correction toner image required for the correction operation, a lubricant suppression toner image is formed on the intermediate transfer belt 421 (toner image forming unit). As a result, when the toner image is primarily transferred from the photoconductor drum 413 to the intermediate transfer belt 421, the lubricant suppression toner image reduces the opportunity (area) for the intermediate transfer belt 421 to come into contact with the lubricant. Furthermore, the lubricant suppression toner image transferred to the intermediate transfer belt 421 supplies toner to the intermediate transfer belt 421 in addition to the correction toner image. As described in step S13, the toner acts as an abrasive, improving the lubricant removal effect.

In addition, the correction operation typically includes ATVC control, toner concentration adjustment, potential correction on the photoconductor drum 413, color registration correction, etc. In this modified example, the operation contents, such as the toner image for correction, the toner image for lubricant suppression, and the time required for the correction operation, can be appropriately changed taking into account these controls, adjustments, and corrections.

As described above, the image forming device 1 of this modified example includes a toner image forming unit that forms a toner image for removing lubricant on the intermediate transfer belt 421 during the correction operation, other than the correction toner image required for the correction operation.

According to the image forming device 1 of this modified example configured in this way, a toner image for removing lubricant is formed on the intermediate transfer belt 421 in the correction operation, so that the lubricant on the intermediate transfer belt 421 can be removed by the toner that acts as an abrasive. This makes it possible to reduce the amount of lubricant on the intermediate transfer belt 421. As a result, it is possible to improve the transferability to textured paper.

[Modification 4]
In this modification, the configuration of the image forming apparatus 1 is as described in the above embodiment. Also, in this modification, the method of reducing the amount of lubricant performed by the image forming apparatus 1 is basically the same as in the above embodiment (see FIG. 7). However, in this modification, the configuration and operation of the lubricant supply unit 450 in relation to the correction operation are different from those in the above embodiment (see FIG. 6).

In this modified example, the lubricant supply unit 450 is spaced away from the photoconductor drum 413 to prevent the lubricant from adhering during the correction operation.

Referring to FIG. 6, the lubricant supply unit 450 further has a cam 455. The support metal plate 454 supports the brush 451 and the lubricant 452, and extends outward from the side of the lubricant 452. The cam 455 is rotatably mounted, and when the cam 455 is rotated to a predetermined angle, it comes into contact with the support metal plate 454, which moves the support metal plate 454 downward. The support metal plate 454 supports the brush 451 and the lubricant 452, and therefore when the support metal plate 454 moves downward, the brush 451 is separated from the photosensitive drum 413.

In the correction operation of step S14 in FIG. 7 described above, the control unit 70 rotates the cam 455 to move the brush 451 away from the photosensitive drum 413, thereby preventing the lubricant from adhering to the photosensitive drum 413.

As described above, in the image forming device 1 of this modified example, the control unit 70 separates the lubricant supply unit 450 from the photoconductor drum 413 during the correction operation.

According to the image forming device 1 of this modified example configured in this way, in the correction operation, the lubricant supply unit 450 can be separated from the photosensitive drum 413 to prevent the lubricant from adhering to the photosensitive drum 413. This makes it possible to reduce the amount of lubricant on the intermediate transfer belt 421. As a result, it is possible to improve the transferability to textured paper.

Note that, here, a cam 455 is used as a separation mechanism for separating the lubricant supply unit 450 from the photoconductor drum 413, but anything other than a cam, such as an actuator, may be used as long as it functions as a separation mechanism.

[Modification 5]
In this modification, the configuration of the image forming apparatus 1 is as described in the above embodiment. Also, in this modification, the method of reducing the amount of lubricant performed by the image forming apparatus 1 is basically the same as in the above embodiment (see FIG. 7). However, in this modification, the operation of the lubricant supply unit 450 with respect to the correction operation is different from that in the above embodiment (see FIG. 6).

In this modified example, in order to prevent the adhesion of lubricant during the correction operation, the control unit 70 stops the supply of lubricant by the lubricant supply unit 450.

Referring to FIG. 6, in the lubricant supply unit 450, the brush 451 that supplies lubricant to the photoconductor drum 413 is connected to a drive motor via a gear and is driven to rotate in the rotation direction R2. Note that the gear and drive motor are not shown. In this modified example, the control unit 70 stops the drive motor when performing the correction operation, thereby stopping the supply of lubricant by the lubricant supply unit 450. In other words, the lubricant supply unit 450 is not operated.

As described above, in the image forming device 1 of this modified example, the control unit 70 stops the supply of lubricant by the lubricant supply unit 450 during the correction operation.

According to the image forming device 1 of this modified example configured in this way, in the correction operation, the supply of lubricant by the lubricant supply unit 450 can be stopped to prevent the lubricant from adhering to the photoconductor drum 413. This makes it possible to reduce the amount of lubricant on the intermediate transfer belt 421. As a result, it is possible to improve the transferability to textured paper.

[Modification 6]
In Modifications 1 and 2, the transferability of textured paper is improved by removing the lubricant from the intermediate transfer belt 421 through a lubricant removal operation. Also, in Modifications 3 to 5, the transferability of textured paper is improved by implementing a correction operation that makes it difficult for the lubricant to adhere to the intermediate transfer belt 421. It is also possible to further improve the transferability of textured paper by combining the lubricant removal operation shown in Modifications 1 and 2 with the correction operation shown in Modifications 3 to 5 that makes it difficult for the lubricant to adhere.

For example, in order to reduce toner consumption, the lubricant removal operation of Modification 1 is combined with the correction operation A2 of Modification 3. Here, after performing the correction operation A2 of Modification 3, the transferability rank was evaluated by changing the conditions of the toner feed amount and the idling time of the removal time free rotation in the lubricant removal operation of Modification 1.

Figure 17 is a graph evaluating the transferability rank for textured paper against the toner feed amount and the idle rotation time of the removal space-time rotation. Here, transferability rank 3 is also set as the acceptable level. In Figure 17, line T2 for transferability rank 3 is shown by a dotted line, and the conditions in the area above line T2 are the acceptable level. In Figure 17, in order to achieve a transferability rank of 3.0, for example, if the conditions for the least amount of toner consumption and the shortest idle rotation time of the removal space-time rotation are set as the lubricant removal operation, the toner feed amount can be set to 1.5 g and the idle rotation time of the removal space-time rotation can be set to 15 seconds. This condition reduces the toner consumption and the idle rotation time of the removal space-time rotation in the lubricant removal operation more than in variant 1.

Figure 18 is a graph evaluating the transferability rank for textured paper when a lubricant removal operation was performed after a correction operation. Specifically, correction operation A5 was performed after correction operation A2, with a toner feed amount of 1.5 g and a lubricant removal operation with an idling time of 15 seconds during removal. Correction operation B2 was performed after correction operation B, with a toner feed amount of 1.5 g and a lubricant removal operation with an idling time of 15 seconds during removal. Correction operation C2 was performed after correction operation C, with a toner feed amount of 1.5 g and a lubricant removal operation with an idling time of 15 seconds during removal.

As can be seen by comparing Figures 16 and 18, the transferability to textured paper is improved in both cases.

[Other Modifications]
In order to improve the transferability of textured paper, an intermediate transfer belt coated with a coating layer mainly composed of glass (SiO ₂ ) (hereinafter, referred to as a coated belt) is used as the intermediate transfer belt 421. With use of such a coated belt, the transferability of textured paper may deteriorate.

The coating layer, which is mainly composed of glass, has an -OH group at the end due to its structure, as shown in Figure 19. It is believed that discharge products have a tendency to adhere to -OH groups, which causes the lubricant to deteriorate and change in quality, resulting in a phenomenon in which transferability deteriorates. When the surface of the coated belt is analyzed by ion chromatography before and after image formation, as shown in Figure 20, _NO3 , which was not detected at the beginning, was detected after 50,000 consecutive sheets of processing, confirming that discharge products adhere to the surface of the coated belt.

In this way, the image forming device 1 that uses a coated belt as the intermediate transfer belt 421 may experience a deterioration in the transferability of textured paper over time, but by adopting a configuration that applies the above embodiment and variations 1 to 6, this deterioration in transferability can be prevented.

The coated belt used as the intermediate transfer belt 421 desirably has a ten-point average roughness Rzjis of 0.6 to 1.3 μm for the following reasons. Specifically, the ten-point average roughness Rzjis is desirably 0.6 μm or more, taking into consideration sensor noise in an optical sensor that optically detects toner on the coated belt, such as the above-mentioned density sensor 461. The ten-point average roughness Rzjis is desirably 1.3 μm or less, taking into consideration the cleaning ability of the coated belt by the main cleaner 426 and sub-cleaner 427 (whether or not there is any wiping residue).

Compared to intermediate transfer belts with a smoother surface, coated belts with this type of surface roughness are more likely to trap lubricant in the recesses caused by the surface roughness, which can lead to poor transferability of textured paper. Even in image forming apparatus 1 that uses such a coated belt, the deterioration of transferability can be prevented by applying the above-mentioned embodiment and variations 1 to 6.

Note that, although a coated belt is shown as an example of the intermediate transfer belt 421 here, the same effect as that of a coated belt can be obtained even if a PI belt or an elastic belt is used instead.

In addition, in the above embodiment and variants 1 to 6, the image carrier is the intermediate transfer belt 421, but the present invention can also be applied when the image carrier is the photosensitive drum 413 and a direct transfer method is used. In this case, the same effects as in the case of the intermediate transfer belt 421 can be obtained.

In addition, in the above embodiment and modified examples 1 to 6, the case where the lubricant supply unit 450 is installed on the photoconductor drum 413 has been exemplified, but the present invention is also applicable to a configuration in which the lubricant supply unit 450 supplies lubricant directly to the intermediate transfer belt 421. In this case as well, the same effect as when it is installed on the photoconductor drum 413 can be obtained.

The above embodiments are merely examples of the implementation of the present invention, and the technical scope of the present invention should not be interpreted in a limiting manner. In other words, the present invention can be implemented in various forms without departing from its gist or main characteristics.

REFERENCE SIGNS LIST 1 Image forming apparatus 10 Image reading section 20 Operation display section 30 Image processing section 40 Image forming section 50 Paper conveying section 60 Fixing section 70 Control section 415 Cleaning unit 421 Intermediate transfer belt 426 Main cleaner 427 Sub-cleaner 450 Lubricant supply section

Claims (12)

an image carrier capable of carrying a toner image;
a lubricant supplying section for supplying a lubricant onto the image carrier;
a control unit that reduces an amount of the lubricant remaining on the image carrier before the toner image is formed on the textured paper, compared to a case in which the toner image is formed on a recording medium other than the textured paper via the image carrier;
An image forming apparatus comprising: a cleaning unit that cleans the lubricant on the image carrier;
The image forming apparatus according to claim 1 . the control unit causes the cleaning unit to clean the lubricant on the image carrier after a correction operation for correcting performance related to image formation has been performed.
The image forming apparatus according to claim 2 . the control unit separates the image carrier from the cleaning unit.
The image forming apparatus according to claim 2 . a toner supplying unit that supplies toner to the cleaning unit to cause the cleaning unit to clean the lubricant together with the toner;
The image forming apparatus according to claim 2 . the cleaning unit has a space for storing the toner;
The image forming apparatus according to claim 5 . the control unit reduces the amount of the lubricant supplied to the image carrier in the correction operation performed when forming an image on the textured paper, compared to a correction operation for correcting performance related to image formation performed when forming an image on a recording medium other than the textured paper.
The image forming apparatus according to claim 1 . a toner image forming unit that forms a second toner image on the image carrier so as to fill a gap between the first toner images required for the correction operation in the correction operation;
The image forming apparatus according to claim 7. the control unit separates the lubricant supply unit from the image carrier in the correction operation.
The image forming apparatus according to claim 7. The control unit stops the supply of the lubricant by the lubricant supply unit in the correction operation.
The image forming apparatus according to claim 7. an image carrier capable of carrying a toner image;
a lubricant supplying section for supplying a lubricant onto the image carrier;
a control unit that reduces an amount of the lubricant on the image carrier before the toner image is formed on the textured paper, compared to when the toner image is formed on a recording medium other than the textured paper via the image carrier;
a toner image forming unit that forms a toner image on the image carrier;
Equipped with
the control unit reduces the amount of the lubricant supplied to the image carrier in the correction operation performed when forming an image on the textured paper, compared to a correction operation for correcting performance related to image formation performed when forming an image on a recording medium other than the textured paper;
the toner image forming unit forms a second toner image on the image carrier in the correction operation so as to fill a gap between the first toner images required for the correction operation.
Image forming device. A selection unit is provided for selecting a type of recording medium on which an image is to be formed,
the control unit reduces the lubricant on the image carrier when the selected recording medium includes textured paper.
The image forming apparatus according to claim 1 .