Image forming apparatus

Abstract

The image forming apparatus includes: an image holding unit; a transfer unit that transfers, to the medium, an image to be transferred to the medium; a removal unit that removes, from the image holding unit, an image that is not intended for transfer to the medium; and a forming unit that forms an image on the image holding unit using the developer, the image being not intended for transfer to the medium, the forming unit having a first forming mode for a first medium and a second forming mode for a second medium having a surface roughness smaller than that of the first medium or a medium density larger than that of the first medium, when a predetermined first medium is used, an image that is not intended for transfer to the medium is formed, and when a second medium is used, an image that is not intended for transfer to the medium is formed between images that are intended for transfer to the medium, and an image that is not intended for transfer to the medium is formed. In the first forming mode, compared with the second forming mode, the forming unit makes the amount of the developer used for forming the image not to be transferred to the medium more.

Description

[0001] This application is a divisional application based on the invention patent application with the invention name “Image forming device”, the application date is June 5, 2020, and the application number is 202010504323.X. Technical Field

[0002] The present disclosure relates to an image forming apparatus. Background Art

[0003] In image forming apparatuses such as copiers, printers, and FAXes, the following Patent Documents 1 to 3 are known as technologies for forming images not intended for transfer to a medium.

[0004] Japanese Patent No. 6340927 discloses a technique for forcibly consuming toner that has been agitated and deteriorated without being consumed within a developing device (14). A band-shaped toner image is formed in a non-image area between toner images. In the technique disclosed in Patent Document 1, when the recording medium width is smaller than the maximum width, the image density of the band-shaped toner image is increased, or the image length is increased to consume more deteriorated toner.

[0005] Japanese Patent Application Publication No. 2006-251138 discloses a technique in which, when a toner band is formed outside an image forming area, the toner band is made lighter when the printed image is darker, and the toner band is made darker when the printed image is lighter, in order to maintain a constant amount of toner supplied to a cleaning device (18).

[0006] Japanese Patent Application Laid-Open No. 2006-221106 describes a technique in which, in a monochrome image forming mode, a toner band is formed on a photosensitive drum not performing image formation to maintain lubricity of a cleaning blade and maximize the toner amount in the toner band of the most upstream photosensitive drum. Summary of the Invention

[0007] The technical problem of the present disclosure is to ensure transferability to a medium with low transfer sensitivity and suppress developer consumption, compared with forming an image for removing discharge products on a medium with low transfer sensitivity in the same manner as on a medium with high transfer sensitivity.

[0008] The present disclosure provides an image forming device comprising: an image holding unit that holds an image formed by using a developer and intended for transfer to a medium and an image not intended for transfer to a medium; a transfer unit that transfers the image intended for transfer to a medium to a medium; a removal unit that removes the image not intended for transfer to a medium from the image holding unit; and a forming unit that forms the image not intended for transfer to a medium on the image holding unit by using a developer, the forming unit having a first forming mode for a first medium and a surface roughness smaller than that of the first medium or a medium density A second forming mode for a second medium larger than the first medium, wherein the first forming mode is a mode for forming the image not intended for transfer to the medium before the image intended for transfer to the medium when using a predetermined first medium, and the second forming mode is a mode for forming the image not intended for transfer to the medium between the images intended for transfer to the medium when using a second medium, wherein in the first forming mode, the forming unit uses a larger amount of developer for forming the image not intended for transfer to the medium than in the second forming mode.

[0009] According to a first embodiment of the present disclosure, an image forming device is provided, comprising: an image holding unit that holds an image formed using a developer for the purpose of transfer to a medium and an image not intended for transfer to a medium; a transfer unit that transfers the image intended for transfer to a medium to a medium; a removal unit that removes the image not intended for transfer to a medium from the image holding unit; and a forming unit that forms the image not intended for transfer to a medium on the image holding unit using a developer, and having a first forming mode for a first medium and a second forming mode for a second medium having a lower transfer sensitivity than the first medium, wherein in the first forming mode, the forming unit uses a larger amount of developer for forming the image not intended for transfer to a medium than in the second forming mode.

[0010] According to the second aspect of the present disclosure, the surface roughness of the first medium is greater than that of the second medium.

[0011] According to a third aspect of the present disclosure, the first medium has a lower medium density than the second medium.

[0012] According to the fourth aspect of the present disclosure, a discriminating unit is provided for discriminating the type of the medium.

[0013] According to the fifth aspect of the present disclosure, the discrimination unit is provided for discriminating a medium having a surface roughness higher than a predetermined value as the first medium.

[0014] According to the sixth aspect of the present disclosure, the discrimination unit is provided for discriminating a medium having a medium density lower than a predetermined value as the first medium.

[0015] According to a seventh aspect of the present disclosure, the forming unit is provided, and in the first forming mode, the forming unit forms the image not intended for transfer to a medium more frequently than in the second forming mode.

[0016] According to the eighth aspect of the present disclosure, when the second medium is used, the density of the image not intended to be transferred to the medium is set to zero.

[0017] According to the 9th scheme of the present disclosure, there is a forming unit that is capable of forming an image using developers of multiple colors, and each time the image that is not intended to be transferred to a medium is formed, the color of the developer constituting the image that is not intended to be transferred to a medium is set.

[0018] According to the tenth aspect of the present disclosure, the forming unit is provided, and the forming unit can form the image not intended for transfer to a medium using the developer of the plurality of colors whose amount of consumption has been the least.

[0019] (Effect)

[0020] According to the first aspect, compared with forming a discharge product removal image on a medium with low transfer sensitivity in the same manner as on a medium with high transfer sensitivity, transferability to the medium with low transfer sensitivity is ensured and developer consumption is suppressed.

[0021] According to the second aspect, transferability to a medium having a large surface roughness and a high transferability sensitivity can be ensured.

[0022] According to the third aspect, transferability to a medium having high transfer sensitivity and low density can be ensured.

[0023] According to the fourth aspect, the first forming mode and the second forming mode can be automatically switched by discriminating the type of the medium.

[0024] According to the fifth aspect, the type of the medium can be automatically determined based on the surface roughness.

[0025] According to the sixth aspect, the type of the medium can be automatically determined based on the density of the medium.

[0026] According to the seventh aspect, the formation frequency can be increased in the first formation mode, and a larger amount of developer can be fed to the removal unit.

[0027] According to the eighth aspect, compared with the case where the density of the image is not set to zero in the case of the second medium, the consumption of the developer can be suppressed.

[0028] According to the ninth aspect, compared with the case where the developer color is not changed, uneven consumption of the developer of a specific color is suppressed.

[0029] According to the tenth aspect, the deteriorated developer can be consumed more easily than in a case where the developer with the least consumption is not used for an image not intended for transfer. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is an overall explanatory diagram of the image forming apparatus of Example 1.

[0031] Figure 2 This is an enlarged explanatory diagram of the visible image forming device of Example 1.

[0032] Figure 3 This is a diagram showing, in block form, the functions of the control unit of the image forming apparatus according to the first embodiment.

[0033] Figure 4 This is an explanatory diagram of an example of the toner belt of Example 1.

[0034] Figure 5 This is an explanatory diagram serving as a flowchart of the toner band forming process according to the first embodiment.

[0035] Figure 6 is an explanatory diagram of the voltage applied to the transfer area. Figure 6 (a) is an explanatory diagram of an example of low-sensitivity paper. Figure 6 (b) is an explanatory diagram of an example of embossed paper. Figure 6 (c) is an explanatory diagram of an example of Japanese paper.

[0036] Figure 7 This is an explanatory diagram of Experimental Example 1 of image quality (embossing level) when embossed paper is used. Figure 7 (a) is a graph with the horizontal axis representing the number of printed sheets and the vertical axis representing the embossing level. Figure 7 (b) is a graph in which the horizontal axis represents adhesion and the vertical axis represents embossing grade.

[0037] Figure 8 1 and 2 are diagrams illustrating images formed in Experimental Example 1.

[0038] Figure 9 is an explanatory diagram of the experimental results of Experimental Example 2. Figure 9 (a) is a graph in which the horizontal axis represents the density of the toner band and the vertical axis represents the embossing level. Figure 9 (b) is a graph in which the horizontal axis represents the density of the toner band and the vertical axis represents the adhesion force.

[0039] Figure 10 This figure is an explanatory diagram showing the results of embossing levels in the image area and the non-image area when the paper type and toner density are changed. DETAILED DESCRIPTION

[0040] Next, specific examples of embodiments of the present disclosure (hereinafter referred to as Examples) will be described with reference to the drawings, but the present disclosure is not limited to the following Examples.

[0041] In addition, in order to make the subsequent description easy to understand, in the accompanying drawings, the front-to-back direction is set as the X-axis direction, the left-to-right direction is set as the Y-axis direction, the up-down direction is set as the Z-axis direction, and the directions or sides indicated by the arrows X, -X, Y, -Y, Z, and -Z are set as the front, rear, right, left, top, and bottom, or the front side, rear side, right side, left side, top, and bottom, respectively.

[0042] In the figure, "○" is written in ” refers to an arrow pointing from the inside of the paper to the outside, and “×” in “○” refers to an arrow pointing from the outside of the paper to the inside.

[0043] In the following description using the drawings, illustration of components other than those necessary for the description is omitted as appropriate for easier understanding.

[0044] [Example 1]

[0045] Figure 1 This is an overall explanatory diagram of the image forming apparatus of Example 1.

[0046] Figure 2 This is an enlarged explanatory diagram of the visible image forming device of Example 1.

[0047] exist Figure 1 In the figure, a copier U as an example of an image forming device includes a user interface UI as an example of an operating unit, a scanner unit U1 as an example of an image reading device, a paper feeder unit U2 as an example of a medium supply device, an image forming unit U3 as an example of an image recording device, and a medium processing device U4.

[0048] (Description of the user interface UI)

[0049] The user interface UI includes input buttons UIa for starting copying, setting the number of copies, etc. The user interface UI also includes a display unit UIb that displays the contents inputted via the input buttons UIa and the status of the copy machine U.

[0050] (Description of the paper feeder unit U2)

[0051] exist Figure 1The paper feeder unit U2 includes a plurality of paper feed trays TR1, TR2, TR3, and TR4, which serve as examples of media storage containers. Furthermore, the paper feeder unit U2 includes a media supply path SH1, which removes recording paper S, which serves as an example of image recording media, stored in the paper feed trays TR1 to TR4 and transports it to the image forming unit U3.

[0052] (Description of Image Forming Unit U3 and Medium Processing Device U4)

[0053] exist Figure 1 The image forming unit U3 includes an image recording unit U3 a that records an image on the recording paper S fed from the paper feeder unit U2 based on the document image read by the scanner unit U1 .

[0054] exist Figure 1 、 Figure 2 In the image forming unit U3, the latent image forming device drive circuit D outputs corresponding drive signals to the Y to K color latent image forming devices ROSy, ROSm, ROSc, and ROSk at predetermined times based on image information input from the scanner unit U1. Below each of the latent image forming devices ROSy to ROSk, photosensitive drums Py, Pm, Pc, and Pk are arranged as an example of an image holder.

[0055] The surfaces of the rotating photosensitive drums Py, Pm, Pc, and Pk are uniformly charged by charging rollers CRy, CRm, CRc, and CRk, respectively, as examples of chargers. Electrostatic latent images are formed on the charged surfaces of the photosensitive drums Py to Pk by laser beams Ly, Lm, Lc, and Lk, as examples of latent image writing light, output by latent image forming devices ROSy, ROSm, ROSc, and ROSk. The electrostatic latent images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are developed into toner images of yellow (Y), magenta (M), cyan (C), and black (K), as examples of visible images, by developing devices Gy, Gm, Gc, and Gk.

[0056] In the developing devices Gy to Gk, developer consumed by development is replenished from toner cartridges Ky, Km, Kc, and Kk, which are examples of developer storage containers. The toner cartridges Ky, Km, Kc, and Kk are detachably mounted on the developer replenishing device U3b.

[0057] The toner images on the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are sequentially transferred, overlappingly, to primary transfer areas Q3y, Q3m, Q3c, and Q3k on the intermediate transfer belt B, an example of an intermediate transfer member, by primary transfer rollers T1y, T1m, T1c, and T1k, thereby forming a color toner image, an example of a multi-color visible image, on the intermediate transfer belt B. The color toner image formed on the intermediate transfer belt B is conveyed to the secondary transfer area Q4.

[0058] In the case of image information of only K color, only the K color photosensitive drum Pk and the developing device Gk are used to form a toner image of only K color.

[0059] After the primary transfer, residual developer, paper dust, and other residues adhering to the surfaces of the photosensitive drums Py, Pm, Pc, and Pk are removed by drum cleaners CLy, CLm, CLc, and CLk, which are examples of cleaners of image holders.

[0060] In Example 1, the photosensitive drum Pk, charging roller CRk, and drum cleaner CLk are integrated into a photosensitive unit UK for color K, serving as an example of an image carrier unit. Similarly, for the other colors Y, M, and C, the photosensitive drums Py, Pm, and Pc, the charging rollers CRy, CRm, and CRc, and the drum cleaners CLy, CLm, and CLc form photosensitive units UY, UM, and UC, respectively.

[0061] Furthermore, the K-color photoreceptor unit UK and the developing device Gk including the developing roller R0k as an example of a developer holding member constitute a visible image forming device UK+Gk for the K-color. Similarly, the Y, M, and C-color photoreceptor units UY, UM, and UC and the developing devices Gy, Gm, and Gc including the developing rollers R0y, R0m, and R0c constitute visible image forming devices UY+Gy, UM+Gm, and UC+Gc for the Y, M, and C colors, respectively.

[0062] A belt module BM, an example of an intermediate transfer device, is located below the photosensitive drums Py-Pk. The belt module BM includes an intermediate transfer belt B, an example of an image retention unit; a drive roller Rd, an example of a driving member for the intermediate transfer element; a tension roller Rt, an example of a tension-applying member; a travel roller Rw, an example of a meandering prevention member; a plurality of idler rollers Rf, an example of a driven member; a support roller T2a, an example of an opposing member; and the primary transfer rollers T1y, T1m, T1c, and T1k. The intermediate transfer belt B is supported so as to be rotatable in the direction of arrow Ya.

[0063] A secondary transfer unit Ut is disposed below the support roller T2a. The secondary transfer unit Ut includes a secondary transfer roller T2b, an example of a secondary transfer component. The area where the secondary transfer roller T2b contacts the intermediate transfer belt B forms a secondary transfer area Q4. Furthermore, the support roller T2a, an example of an opposing component, faces the secondary transfer roller T2b across the intermediate transfer belt B. A contact roller T2c, an example of a power supply component, contacts the support roller T2a. A secondary transfer voltage having the same polarity as the toner charge polarity is applied to the contact roller T2c.

[0064] The backup roller T2 a , the secondary transfer roller T2 b , and the contact roller T2 c constitute a secondary transfer device T2 as an example of a transfer unit.

[0065] A media transport path SH2 is located below the belt module BM. Recording paper S, supplied from the media supply path SH1 of the paper feeder unit U2, is conveyed by transport rollers Ra, an example of a medium transport component, to registration rollers Rr, an example of a component that adjusts the transport timing. Registration rollers Rr transport the recording paper S downstream in sync with the timing of the toner image formed on the intermediate transfer belt B being transported to the secondary transfer area Q4. The recording paper S fed by registration rollers Rr is guided by the registration-side paper guide SGr and the pre-transfer paper guide SG1 and transported to the secondary transfer area Q4.

[0066] When the toner image on the intermediate transfer belt B passes through the secondary transfer area Q4, it is transferred by the secondary transfer device T2 to the recording paper S. In the case of a color toner image, the toner image primarily transferred to the surface of the intermediate transfer belt B is also secondarily transferred to the recording paper S in an overlapping manner.

[0067] The primary transfer rollers T1y to T1k, the secondary transfer device T2, and the intermediate transfer belt B constitute the transfer device T1y to T1k+T2+B of the first embodiment.

[0068] After the secondary transfer, the intermediate transfer belt B is cleaned by a belt cleaner CLB, an example of an intermediate transfer body cleaner, located downstream of the secondary transfer area Q4. The belt cleaner CLB, an example of a removal unit, removes residual materials such as developer and paper dust that remain untransferred in the secondary transfer area Q4 from the intermediate transfer belt B.

[0069] The recording paper S with the toner image transferred thereto is guided by the transferred paper guide SG2 and conveyed to a medium conveying belt BH, which is an example of a conveying member.

[0070] The fixing device F includes a heating roller Fh, an example of a heating member, and a pressure roller Fp, an example of a pressure member. The recording paper S is conveyed to the area where the heating roller Fh and the pressure roller Fp contact, namely, the fixing area Q5. The toner image on the recording paper S is heated and pressurized by the fixing device F as it passes through the fixing area Q5, thereby being fixed.

[0071] The visible image forming devices UY+Gy to UK+Gk, the transfer devices T1y to T1k+T2+B, and the fixing device F constitute an image recording portion U3a as an example of the image forming unit of the first embodiment.

[0072] A switching gate GT1, an example of a switching member, is provided on the downstream side of the fixing device F. The switching gate GT1 selectively switches the recording paper S after passing through the fixing area Q5 to either the discharge path SH3 or the reversing path SH4 on the side of the media processing device U4. The recording paper S transported to the discharge path SH3 is transported to the paper transport path SH5 of the media processing device U4. A curl correction member U4a, an example of a warp correction member, is provided on the paper transport path SH5. The curl correction member U4a corrects the warping, or so-called curl, of the fed recording paper S. The recording paper S, after the curl has been corrected, passes through the discharge roller Rh, an example of a medium discharge member, and is discharged to the discharge tray TH1, an example of a medium discharge portion, with the image-fixed surface of the paper facing upward.

[0073] The recording paper S conveyed to the reversing path SH4 of the image forming unit U3 through the switching gate GT1 passes through the second gate GT2 as an example of a switching member and is conveyed to the reversing path SH4 of the image forming unit U3 .

[0074] At this time, when the recording paper S is discharged with the image-fixed surface facing downward, the recording paper S's conveying direction is reversed after the trailing end of the recording paper S passes through the second gate GT2. In Example 1, the second gate GT2 is constructed of a film-like elastic member. Therefore, the second gate GT2 allows the recording paper S, which has been conveyed through the reversing path SH4, to temporarily pass through. After passing through the second gate GT2, the recording paper S is reversed, or so-called switched back, and then directed to the conveying paths SH3 and SH5. The switched back recording paper S then passes through the curl correction unit U4a and is discharged onto the discharge tray TH1 with the image-fixed surface facing downward.

[0075] The reversing path SH4 of the image forming unit U3 is connected to the circulation path SH6. A third gate GT3, an example of a switching member, is disposed at the connection portion. The downstream end of the reversing path SH4 is connected to the reversing path SH7 of the media processing device U4.

[0076] The recording paper S conveyed to the reversing path SH4 through the switching gate GT1 passes through the third gate GT3 and is conveyed to the reversing path SH7 of the media processing device U4. The third gate GT3 of Example 1, like the second gate GT2, is constructed from a film-like elastic member. Therefore, the third gate GT3 temporarily allows the recording paper S conveyed through the reversing path SH4 to pass through. After passing through, the recording paper S is switched back and directed to the circulation path SH6.

[0077] The recording paper S conveyed to the circulation path SH6 is conveyed again to the secondary transfer area Q4 through the medium conveyance path SH2 to perform printing on the second side.

[0078] The elements SH1 to SH7 constitute a paper transport path SH. The elements SH, Ra, Rr, Rh, SGr, SG1, SG2, BH, and GT1 to GT3 constitute a paper transport device SU of the first embodiment.

[0079] (Description of the Control Unit of Example 1)

[0080] Figure 3 This is a diagram showing, in block form, the functions of the control unit of the image forming apparatus according to the first embodiment.

[0081] exist Figure 3 In the embodiment, the control unit (controller) C, an example of a control unit of the copier U, has an input / output interface (I / O) for inputting and outputting signals to and from the outside. Furthermore, the control unit C has a ROM (Read Only Memory) that stores programs and information used to perform required processing. Furthermore, the control unit C has a RAM (Random Access Memory) for temporarily storing required data. Furthermore, the control unit C has a CPU (Central Processing Unit) that performs processing according to the programs stored in the ROM. Therefore, the control unit C in Example 1 is composed of a small information processing device, a so-called microcomputer. Therefore, the control unit C can realize various functions by executing the programs stored in the ROM.

[0082] (Signal output element connected to control unit C)

[0083] The control unit C receives an output signal from a signal output element such as a user interface UI.

[0084] The user interface UI includes, as examples of input means, a copy start key, numeric keys, and input buttons UIa for inputting arrow keys and the like.

[0085] (Controlled element connected to control unit C)

[0086] The control unit C is connected to the driving circuit D1 of the main driving source, the power supply circuit E, and other control elements (not shown). The control unit C outputs control signals to the circuits D1, E, and the like.

[0087] D1: driving circuit of the main driving source

[0088] The driving circuit D1 of the main driving source rotationally drives the photosensitive drums Py to Pk, the intermediate transfer belt B, and the like via a main motor M1 as an example of the main driving source.

[0089] E: Power circuit

[0090] The power supply circuit E includes a power supply circuit Ea for development, a power supply circuit Eb for charging, a power supply circuit Ec for transfer, and a power supply circuit Ed for fixing.

[0091] Ea: Power supply circuit for development

[0092] The power supply circuit Ea for development applies a development voltage to the developing rollers of the developing devices Gy to Gk.

[0093] Eb: Power supply circuit for live use

[0094] The charging power supply circuit Eb applies a charging voltage for charging the surfaces of the photosensitive drums Py to Pk to the charging rollers CRy to CRk, respectively.

[0095] Ec: Power supply circuit for transfer

[0096] The power supply circuit Ec for transfer applies a transfer voltage to the primary transfer rollers T1y to T1k and the backup roller T2a.

[0097] Ed: Power supply circuit for fixing

[0098] The fixing power supply circuit Ed supplies power to the heater of the heating roller Fh of the fixing device F.

[0099] (Function of control unit C)

[0100] The control unit C has the following functions: executing processing according to the input signal from the signal output element and outputting a control signal to each of the control elements.

[0101] C1: Control unit for image formation

[0102] The image formation control unit C1 controls the driving of components of the scanner unit U1 and the image forming unit U3 and the timing of applying voltages based on input to the user interface UI or image information input from an external personal computer, thereby executing image forming operations.

[0103] C2: Control unit of the drive source

[0104] The driving source control unit C2 controls the driving of the main motor M1 via the main driving source driving circuit D1 , thereby controlling the driving of the photosensitive drums Py to Pk and the like.

[0105] C3: Control unit of the power circuit

[0106] The power supply circuit control unit C3 controls the power supply circuits Ea to Ed, thereby controlling the voltage applied to each component and the power supplied to each component.

[0107] C4: Storage unit of media type

[0108] The media type storage unit C4 stores the type of recording paper S, an example of the media being used. The media type storage unit C4 of Example 1 stores the type of recording paper S stored in each of the paper feed trays TR1 to TR4 of the paper feeder unit U2, for each of the paper feed trays TR1 to TR4. Furthermore, in Example 1, the type of recording paper S stored in each of the paper feed trays TR1 to TR4 is stored as a type set and registered via input from the user interface UI. The type of recording paper S can be selected from among "thin paper," "plain paper," "thick paper," "embossed paper," "Japanese paper," "coated paper," and other options. For example, the type of recording paper S can be set by directly inputting the "paper basis weight."

[0109] C5: Medium type identification unit

[0110] The media type determination unit C5 determines the type of recording paper S used for printing. The media type determination unit C5 of Example 1 determines the type of recording paper S based on the information on the types of recording paper S in the paper feed trays TR1 to TR4 stored in the media type storage unit C4 and the paper feed trays TR1 to TR4 used for printing. Furthermore, the media type determination unit C5 of Example 1 determines whether the recording paper S is embossed paper or Japanese paper, an example of media with high transfer sensitivity, or thin paper, plain paper, thick paper, or coated paper, an example of media with low transfer sensitivity.

[0111] In addition, in the present specification and claims, "transfer sensitivity" indicates the difficulty of transferring an image to recording paper S, and vice versa, the ease of transfer. Even when there are slight changes in the environment such as temperature and humidity, or in the applied voltage, or in the conveying speed, poor transfer is easily produced as "high transfer sensitivity", and conversely, poor transfer is not easily produced as "low transfer sensitivity". Therefore, thin paper, ordinary paper, thick paper, and coated paper with a smooth surface and roughly uniform density of fibers such as pulp have low transfer sensitivity. On the other hand, embossed paper with uneven surfaces, Japanese paper (low-density medium) with uneven density of pulp and the like and containing many voids inside have high transfer sensitivity. Figure 6 This is described because when a transfer voltage is applied to embossed paper and Japanese paper, the resistance is different between the recessed parts and gaps (parts without fibers) and the parts with fibers, and discharge occurs in the recessed parts and gaps. At this time, the transfer voltage fluctuates and poor transfer is likely to occur.

[0112] In the following description, embossed paper and Japanese paper may be described as “high-sensitivity paper” as an example of the first medium, and plain paper may be described as “low-sensitivity paper” as an example of the second medium.

[0113] In Example 1, the media type is determined based on the information stored in the media type storage unit C4, but the present invention is not limited to this. For example, a sensor, as an example of a detection component, can be provided on the paper feed trays TR1-TR4 of the paper feeder unit U2, or on the transport paths SH1 and SH2 from the paper feed trays TR1-TR4 to the registration rollers Rr, to detect and determine the type of recording paper S used for printing. This detection component detects the media type based on the thickness, light transmittance, light reflectance, polarization characteristics, surface roughness, and other factors. Therefore, for example, if the surface roughness of the recording paper S detected by the sensor exceeds a predetermined value (threshold), that is, if the surface roughness is large, the recording paper can be determined to be high-sensitivity paper. Furthermore, if the density (weight / (thickness x area)) of the recording paper S detected by the sensor is less than a predetermined value (threshold), that is, if the recording paper S has a large amount of internal voids, the recording paper can be determined to be high-sensitivity paper.

[0114] C6: Counting unit for the number of printed sheets

[0115] The print count unit C6, an example of a unit for counting the number of transfers, counts the number of prints, an example of the number of transfers. Specifically, the print count unit C6 counts the number of times a print image has been transferred to recording paper S. The print image is an example of an image intended for transfer. In Example 1, the print count is initialized, i.e., reset, when a toner band (described later) is formed. The toner band is an example of an image not intended for transfer.

[0116] C7: Developer consumption detection unit

[0117] The developer consumption detection unit C7 detects the amount of developer consumed during image formation. The developer consumption detection unit C7 of Example 1 calculates and accumulates the developer consumption for each color based on the number of pixels written to the latent image forming devices ROSy to ROSk, thereby detecting the consumption. Furthermore, the developer consumption is not limited to being based on the number of pixels written to the latent image forming devices ROSy to ROSk. Developer consumption can also be derived based on, for example, the density of a read image or changes in the weight of the developing devices Gy to Gk that contain the developer.

[0118] Figure 4 This is an explanatory diagram of an example of the toner belt of Example 1.

[0119] C8: Toner band formation timing determination unit

[0120] The toner band formation timing determination unit C8 determines whether the time has arrived for forming a toner band 1, an example of an image not intended for transfer. In Example 1, the toner band formation timing is set to occur at the start of a job when switching from low-sensitivity paper to high-sensitivity paper, each time an inter-image area 3 is formed in a job using high-sensitivity paper, and after a predetermined number of sheets of low-sensitivity paper have been printed continuously. Specifically, when low-sensitivity paper was used in the previous job and high-sensitivity paper was switched from the current job, a recovery mode, an example of an operation for forming a toner band 1, is executed before a series of image formation operations (jobs) such as copying or printing one or more sheets, is started. Furthermore, in jobs using high-sensitivity paper, the toner band 1 is set to be formed in the inter-image area 3, which is the non-image area between printed images 2, an example of an image intended for transfer. Furthermore, it is set so that a toner band is formed in the inter-image area 3 when 5000 sheets, which is an example of a predetermined number of sheets, are continuously printed using low-sensitivity paper.

[0121] In addition, in Example 1, the case where the colorant band 1 is formed in all the inter-image areas 3 in the case of high-sensitivity paper is illustrated, but the present invention is not limited to this. The colorant band 1 can also be formed once in 2 times in the inter-image area 3, or once more than 3 times.

[0122] C9: Color determination unit

[0123] The color determination unit C9 determines the color of the toner band 1 to be formed. The color determination unit C9 of Example 1 determines the color of the toner band 1 to be formed during operation with high-sensitivity paper or printing with low-sensitivity paper, with operation with high-sensitivity paper or printing with low-sensitivity paper serving as an example of a time period for forming the toner band 1. That is, the color of the toner band 1 is determined each time the toner band 1 is formed. Furthermore, the color determination unit C9 of Example 1 determines the color with the lowest developer consumption as the color to be formed with the toner band 1, based on the developer consumption of each color detected by the developer consumption detection unit C7. This is not limiting; two or three colors from the four colors of Y, M, C, and K, in order of decreasing developer consumption, may be used. Furthermore, the color determination unit C9 is not limited to the case of low developer consumption; any parameter associated with developer degradation may be used. For example, parameters may be used in which the developing devices Gy to Gk are operated for a certain period of time or longer with the consumption amount being below a predetermined threshold value to stir the developer, or in which the amount of developer supplied to the developing devices Gy to Gk is small.

[0124] C10: Toner band forming unit

[0125] The toner band forming unit C10 forms a toner band 1 as an example of a developer supply image to the cleaning unit. In the recovery mode, an example of the first forming mode, the toner band forming unit C10 of Example 1 forms an image with a 10% density for each of the Y, M, C, and K colors, corresponding to 100 A4 sheets, or 10 A4-sized solid images, with no recording paper S being conveyed. This image, with a total density of 40%, is then applied to the toner band 1 as an example of a band-shaped image. A voltage of opposite polarity to the secondary transfer voltage is applied to the toner band 1 in the secondary transfer area Q4, and the developer from the toner band 1 is supplied to the belt cleaner CLB.

[0126] Furthermore, the toner band forming unit C10 of Example 1 executes the high-sensitivity paper mode, which is an example of a first forming mode, during printing on high-sensitivity paper, and forms a toner band 1 for each inter-image area 3 using the color determined by the color determining unit C9. Furthermore, when printing on low-sensitivity paper, the toner band forming unit C10 executes the low-sensitivity paper mode, which is an example of a second forming mode, and forms a toner band 1 in the inter-image area 3 every 5,000 pages using the color determined by the color determining unit C9.

[0127] Furthermore, the density of the toner band 1 per 5,000 pages when printing on low-sensitivity paper is lower than that when printing on high-sensitivity paper. This reduces developer usage. For example, the density of the toner band 1 can be set to 0.75% for high-sensitivity paper and 0.25% for low-sensitivity paper. The density of the toner band 1 for high-sensitivity paper is preferably set to 0.5% or higher, and more preferably to 0.75% or higher. While the example shows a case where the density of the toner band 1 for low-sensitivity paper is set to 0.25%, this is not limiting. A setting of 0% is also possible, meaning that no toner band 1 is formed for low-sensitivity paper. By not forming the toner band 1 for low-sensitivity paper, overall developer consumption can be further reduced. The present specification and claims also encompass the use of the toner band 1 for low-sensitivity paper at a density of 0%.

[0128] Furthermore, even if the toner bands 1 on low-sensitivity paper and high-sensitivity paper have the same density, the toner bands 1 are formed more frequently on the high-sensitivity paper, and the total amount of developer used is also greater on the high-sensitivity paper.

[0129] Furthermore, in Example 1, the size of the toner ribbon 1, namely, the length L0 and width L1 of the toner ribbon 1 in the direction in which it is conveyed on the intermediate transfer belt B, are set to predetermined dimensions. As an example, width L1 is set to correspond to the width of the largest print image 2a (e.g., A3) that can be formed by the copier U. Therefore, the width is set to cover the entire width of the smallest print image (e.g., A5). Alternatively, width L1 can be set to a length that exceeds the width of the largest print image 2a but is not larger than the width of the intermediate transfer belt B.

[0130] Furthermore, the longer the length L0 and width L1 of the intermediate transfer belt B in the transport direction, the greater the amount of developer used. Therefore, in Example 1, the density was increased for high-sensitivity paper. However, it is also possible to increase the width L1 or length L0 without increasing the density, or to increase the length L0 while increasing the density.

[0131] (Description of Flowchart of Example 1)

[0132] Next, the control flow in the copy machine U according to the first embodiment will be described using a flowchart, that is, a so-called flow chart.

[0133] (Flowchart Description of Toner Band Formation Process)

[0134] Figure 5 This is an explanatory diagram of a flowchart of the toner band forming process of the first embodiment.

[0135] According to the program stored in the control unit C of the copy machine U, Figure 5 The processing of each step ST of the flowchart of FIG. In addition, this processing can also be executed in parallel with other various processing of the copy machine U. Therefore, the processing of forming an image on each recording paper S with the start of the job is the same as the processing of forming an image on each recording paper S with the start of the job. Figure 5 The flowcharts are executed in parallel.

[0136] Figure 5 The flowchart shown is started when the power of the copy machine U is turned on.

[0137] exist Figure 5 In ST1 of FIG. 1 , it is determined whether the operation has started. If the answer is “yes” (Y), the process proceeds to ST2 . If the answer is “no” (N), ST1 is repeated.

[0138] In ST2 , it is determined whether the type of recording paper S has been changed from low-sensitivity paper to high-sensitivity paper. If yes (Y), the process proceeds to ST3 , and if no (N), the process proceeds to ST4 .

[0139] In ST3, the recovery mode is executed before forming the print image 2. Specifically, in the recovery mode, an image with a density of 40% is formed to correspond to 100 A4 sheets, that is, 10 A4-sized solid images. Then, the process proceeds to ST5.

[0140] In ST4 , it is determined whether the recording paper S for which the job is started is high-sensitivity paper. If yes (Y), the process proceeds to ST5 , and if no (N), the process proceeds to ST7 .

[0141] In ST5, formation of the print image 2 is started, and a high-density toner band 1 for high-sensitivity paper is formed in the inter-image area 3. Then, the process proceeds to ST6.

[0142] In ST6 , it is determined whether the work has been completed. If it is “yes” (Y), the process returns to ST1 , and if it is “no” (N), ST6 is repeated.

[0143] In ST7, formation of the print image 2 is started, and counting of the number of prints is started. Then, the process proceeds to ST8.

[0144] In ST8 , it is determined whether the toner band formation time has arrived. In other words, it is determined whether the counted number of printed sheets has reached the determination threshold of 5,000 sheets. If the answer is "yes" (Y), the process proceeds to ST9 ; if not, the process proceeds to ST10 .

[0145] In ST9 , the following processes ( 1 ) and ( 2 ) are executed, and the process proceeds to ST10 .

[0146] (1) A low-density toner band 1 is formed for low-sensitivity paper.

[0147] (2) Reset the number of prints. In other words, perform initialization.

[0148] In ST10 , it is determined whether the work has been completed. If it is “yes” (Y), the process returns to ST1 , and if it is “no” (N), the process returns to ST7 .

[0149] (Effect of Example 1)

[0150] In the copier U of Example 1 having the above-described structure, during the image forming operation, a print image 2 is secondary transferred from the intermediate transfer belt B to recording paper S. During this process, localized discharge occurs in the secondary transfer area Q4, depositing discharge products on the intermediate transfer belt B. The discharge products are removed by the belt cleaner CLB, but some remain on the intermediate transfer belt B, increasing in size over time. As a result, the adhesion between the intermediate transfer belt B and the developer of the primary transferred print image 2 increases. Furthermore, this increased adhesion makes it difficult for the developer to be transferred to the recording paper S during the secondary transfer process. Consequently, transfer failures are more likely to occur, leading to image quality defects.

[0151] To address the increase in discharge products over time, non-transferable images, such as toner bands, have been formed. Lubricants and other external additives are added to the developer, which is then fed to the belt cleaner (CLB) to improve its cleaning performance and remove any remaining discharge products.

[0152] Figure 6 is an explanatory diagram of the voltage applied to the transfer area. Figure 6 (a) is an explanatory diagram of an example of low-sensitivity paper. Figure 6 (b) is an explanatory diagram of an example of embossed paper. Figure 6 (c) is an explanatory diagram of an example of Japanese paper.

[0153] Figure 6In the low-sensitivity paper S1 such as plain paper, the surface is smooth and there are almost no voids inside. Therefore, the secondary transfer voltage V1 is applied substantially uniformly in the secondary transfer area Q4.

[0154] On the other hand, Figure 6 As shown in (b), embossed paper S2, an example of highly sensitive paper, has uneven surfaces. In concave portions S2a, gaps 12 are formed between the paper and the intermediate transfer belt B. Consequently, the resistance in the thickness direction varies between the convex portions S2b (without gaps 12) and the concave portions S2a (with gaps 12). Consequently, discharge is more likely to occur in gaps 12, potentially changing the secondary transfer voltage V1a applied to concave portions S2a. Consequently, transfer failures are more likely to occur in concave portions S2a than in low-sensitivity paper S1.

[0155] Figure 6 In (c), Japanese paper S3, an example of highly sensitive paper, is prone to internal voids (gaps) 13. Similar to the case of embossed paper S2, the portions with voids 13 are more likely to experience transfer failure than the portions without voids 13. This means that transfer failure is also likely to occur with low-density recording paper S, not just Japanese paper.

[0156] Therefore, when using high-sensitivity paper S2 or S3 under conditions where transfer failure is likely to occur due to the buildup of discharge products over time, transfer failure is more likely to occur. Therefore, high-sensitivity paper S2 or S3 is more susceptible to the effects of discharge products (higher sensitivity) than low-sensitivity paper S1.

[0157] In contrast, in Example 1, when using high-sensitivity paper S2 or S3, the amount of developer used in the toner belt 1 is increased compared to when using low-sensitivity paper S1. Specifically, the removal of discharge products is improved compared to when using low-sensitivity paper S1, resulting in a state where fewer discharge products are deposited on the intermediate transfer belt B. Therefore, compared to conventional methods that form a uniform toner belt regardless of paper type, the use of high-sensitivity paper S2 or S3 reduces the adverse effects of discharge products, making transfer defects less likely to occur.

[0158] In particular, in Example 1, when recording paper S is changed from low-sensitivity paper S1 to high-sensitivity paper S2 or S3, a recovery mode is executed to remove discharge products from the intermediate transfer belt B. Therefore, compared to when the recovery mode is not executed, the print image 2 is printed with fewer discharge products on the surface of the intermediate transfer belt B, thereby reducing the occurrence of transfer defects on the high-sensitivity paper S2 or S3.

[0159] Furthermore, during a job using high-sensitivity paper S2 or S3, a toner band 1 is formed for each inter-image area 3. Therefore, compared to a case where no toner band 1 is formed, the cleaning capacity of the belt cleaner CLB is maintained at a high level, making it easier to continuously remove discharge products from the surface of the intermediate transfer belt B during the job. In other words, the surface of the intermediate transfer belt B is more likely to be kept low. Consequently, transfer failures caused by accumulated discharge products during the job are reduced.

[0160] Furthermore, a low-density toner band 1 is formed regularly (every 5,000 sheets) on low-sensitivity paper S1, which is less susceptible to transfer failure. This regularly removes discharge products, suppressing transfer failure and minimizing toner consumption compared to forming a high-density toner band.

[0161] Furthermore, in Example 1, the developer used in both high-sensitivity and low-sensitivity paper modes is set to the developer with the lowest consumption. When developer consumption is low, the proportion of deteriorated developer due to agitation within the corresponding developing devices Gy-Gk increases. Therefore, by forcibly using deteriorated developer as the toner belt 1, replacement of deteriorated developer is facilitated. Furthermore, when the proportion of deteriorated developer decreases due to developer replacement, development and transfer defects are reduced.

[0162] (Experimental example)

[0163] Figure 7 This is an explanatory diagram of Experimental Example 1 of image quality (embossing level) when embossed paper is used. Figure 7 (a) is a graph with the horizontal axis representing the number of printed sheets and the vertical axis representing the embossing level. Figure 7 (b) is a graph in which the horizontal axis represents adhesion and the vertical axis represents embossing grade.

[0164] Next, an experiment was conducted to confirm the effects of the present disclosure.

[0165] (Experimental Example 1)

[0166] In Experimental Example 1, an experiment was conducted to see how the image quality (embossing level) changes when continuous printing is performed on embossed paper without forming a toner band. In the experiment, leather paper (レザック) 66 manufactured by Tokuju Tokai Paper Co., Ltd. was used as the embossed paper. In addition, the black leather paper 66 is described as "leather paper K" and the blue leather paper 66 is described as "leather paper B". In addition, as the image forming device, Versant 3100Press manufactured by Fuji Xerox Co., Ltd. was used. In the experiment, the image quality (embossing level) of the image having the image portion 21 and the non-image portion 22 was tested in the new state (printed 0 sheets) and 5000 sheets (5kPV) of the image having the image portion 21 and the non-image portion 22 were printed (see the following). Figure 8 ) state, a black solid surface (density 100%) and a halftone image with a density of 60%, as well as a blue solid surface (density 100%) and a halftone image with a density of 60% were formed, and the embossing level and the adhesion of the developer to the intermediate transfer belt B at this time were measured.

[0167] In the measurement of adhesion force, the intermediate transfer belt B was stopped while the developer was still attached to it, and air was blown onto the developer. The average adhesion force (nN) per developer was calculated based on the pressure of the blown air when the developer was visually blown off.

[0168] The embossing grade was visually observed for the roughness of the image. An embossing grade of 3 or less was considered acceptable.

[0169] Figure 8 1 and 2 are diagrams illustrating images formed in Experimental Example 1.

[0170] In addition, in Experimental Example 1, Figure 8 As shown, three image portions 21 are formed as an image, spaced apart from each other, and non-image portions 22 are formed between the image portions 21. That is, in the width direction of the intermediate transfer belt B, developer is supplied to the belt cleaner CLB in the area corresponding to the image portions 21, while developer is not supplied to the belt cleaner CLB in the area corresponding to the non-image portions 22.

[0171] Figure 7 In (a), it was confirmed that the embossing level decreased over time in the portion corresponding to the non-image portion 22, when no toner bands were formed. Specifically, it was confirmed that embossed paper could be printed within an acceptable level even in portions such as the image portion 21, where developer was continuously supplied, while image quality deteriorated in portions such as the non-image portion 2, where developer was not supplied.

[0172] exist Figure 7 In (b), a tendency was observed: while there was some variation, the developer adhesion to the intermediate transfer belt B increased during continuous printing in the non-image area 22, resulting in a worsening of the embossing level. Furthermore, it was confirmed that the embossing level fell within the allowable range, at least when the adhesion was less than 30 [nN].

[0173] (Experimental Example 2)

[0174] Figure 9 is an explanatory diagram of the experimental results of Experimental Example 2. Figure 9 (a) is a graph in which the horizontal axis represents the density of the toner band and the vertical axis represents the embossing level. Figure 9 (b) is a graph in which the horizontal axis represents the density of the toner band and the vertical axis represents the adhesion force.

[0175] In Experimental Example 2, the relationship between the density of the toner band 1 and the embossing level and the adhesion was observed. In Experimental Example 2, the experiment was conducted under the same experimental conditions as in Experimental Example 1.

[0176] Figure 9 In the case where the density of the toner band 1 is "0%", that is, 5000 sheets are printed without forming the toner band 1, Figure 9 As shown in the upper section of the graph "0%", the embossing level was poor, at "4", and the adhesion was also poor, at 32 nN. Furthermore, when recovery mode was executed from this state, as shown in the lower section of the graph "0%", the embossing level recovered to "3", and the adhesion also recovered to approximately 29.7 nN.

[0177] Furthermore, it was confirmed that when the density of the toner band 1 was "0.5%" and 5,000 sheets were printed, the print quality improved compared to the "0%" condition. At a density of "0.75%" or higher, the embossing level stabilized at 3 or lower, and the adhesion also stabilized at 30 nN or lower. Therefore, it was confirmed that for embossed paper, a toner band density of 0.5% or higher is preferable, and 0.75% or higher is particularly preferable.

[0178] Figure 10 This figure is an explanatory diagram showing the results of embossing levels in the image area and the non-image area when the paper type and toner density are changed.

[0179] like Figure 10 As shown, experiments were conducted using J paper (plain paper) and OSC paper (coated paper) manufactured by Fuji Xerox Co., Ltd. as examples of low-sensitivity paper, Korean paper Rendezvous (rough paper) as an example of high-sensitivity paper, and leather-grained paper (embossed paper) and snow-grained paper (embossed paper) manufactured by Tokuju Dongkai Paper Co., Ltd. The leather-grained paper used was the same as in Experimental Example 1.

[0180] according to Figure 10 The results showed that on low-sensitivity paper, no transfer failure occurred in either the image area 21 or the non-image area 22. This confirmed that even with a low density (0%) of toner band 1, there were few problems. On the other hand, on high-sensitivity paper, when the density of toner band 1 was low, image quality deteriorated in the non-image area, and that higher density of toner band 1 improved image quality.

[0181] In addition, Figure 10 In the experimental example of , an experiment was conducted to confirm whether the results differed between the black toner band 1 and the blue toner band 1. As a result, no difference was observed in the embossing level depending on the color of the developer.

[0182] (Change Example)

[0183] While the embodiments of the present disclosure have been described in detail above, the present disclosure is not limited to the embodiments described above, and various modifications can be made within the scope of the gist of the present disclosure as described in the claims. Modifications (H01) to (H08) of the present disclosure are exemplified below.

[0184] (H01) While the above embodiment illustrates a copy machine U as an example of an image forming device, the present invention is not limited to this and can also be applied to a fax machine or a multifunction device that has multiple functions such as a fax machine, a printer, and a copy machine. Furthermore, the present invention is not limited to an image forming device that develops multiple colors and can also be configured as a monochrome image forming device.

[0185] (H02) In the above-described embodiments, the specific numerical values ​​exemplified can be appropriately changed according to changes in design and specifications.

[0186] (H03) The above embodiment illustrates a case where a toner band 1 is formed in each inter-image area 3 of high-sensitivity paper, that is, for each printed image 2, and every 5,000 sheets of low-sensitivity paper. However, this is not limiting. It is preferable to form toner bands 1 frequently on high-sensitivity paper and less frequently on low-sensitivity paper. However, as long as toner consumption is acceptable, the same frequency can be used on low-sensitivity paper. However, in this case, the density of the toner band 1 must be higher for high-sensitivity paper than for low-sensitivity paper.

[0187] Furthermore, the frequency of forming the toner band is exemplified as being every 1 sheet or every 5,000 sheets, but the frequency is not limited thereto and can be variable. For example, as the intermediate transfer belt B deteriorates over time, the number of uses of the intermediate transfer belt B (the cumulative number of printed sheets since it was brand new) increases. Therefore, correction can be performed to change the toner band formation from every 5,000 sheets to every 4,000 sheets to account for the deterioration of the intermediate transfer belt B over time.

[0188] (H04) In the above embodiment, the recovery mode is preferably executed, but the recovery mode may not be executed. Furthermore, in the case of low-sensitivity paper, the toner band 1 is formed once every 5,000 sheets. However, the recovery mode may be executed once every 5,000 sheets, for example.

[0189] Furthermore, in recovery mode, the density and area of ​​the toner band formed in recovery mode (corresponding to 100 A4 pages) can be adjusted based on, for example, the number of sheets of low-sensitivity paper used continuously before switching to high-sensitivity paper. Specifically, while using low-sensitivity paper, toner band 1 is formed only infrequently. If low-sensitivity paper is used for extended periods, significant discharge products may accumulate on the intermediate transfer belt B. Therefore, the more sheets of low-sensitivity paper are printed before switching to high-sensitivity paper, the higher the density and larger the area of ​​toner band 1. The fewer sheets of low-sensitivity paper are printed, the lower the density and smaller the area of ​​toner band 1.

[0190] (H05) While the above embodiment illustrates a case where the toner strip 1 is set to a color that consumes less, the present invention is not limited to this. A specific color can be fixed, and a configuration can be made in which a developer dedicated to the toner strip is provided in addition to the four colors. Furthermore, a configuration can be made in which the toner strip 1 is formed in two or three specific colors, or in all four colors.

[0191] (H06) In the above embodiment, the recovery mode is preferably executed before a job starts, but it can also be executed at the end of each job. Furthermore, if printing on high-sensitivity paper is continuous, printing can be temporarily stopped every specified number of sheets (e.g., 500 sheets) and the recovery mode can be executed.

[0192] (H07) While the above embodiment illustrates a belt-shaped toner belt 1 as an example of an image not intended for transfer, this is not limiting. The shape, size, and number of toner belts can be modified according to design and specifications. Specifically, instead of a belt shape, polygonal or circular graphics or characters can be used, and the size and number can also be modified. Furthermore, without changing the density, the size can be increased to increase the amount of developer used, thereby increasing the amount of developer delivered to the belt cleaner CLB.

[0193] (H08) While the above embodiment illustrates increasing the amount of developer used to suppress transfer defects with high-sensitivity paper, transfer defects can also be suppressed by, for example, suppressing developer adhesion to the image retention unit or improving the ability to remove discharge products, thereby facilitating developer transfer. Specifically, when printing with high-sensitivity paper, an operating mode that suppresses adhesion compared to printing with low-sensitivity paper can be implemented. Furthermore, this operating mode can be implemented in place of or in addition to the various forming modes described in the embodiments. Specifically, as an example of improving the ability to remove discharge products from the image retention unit, at least one of the area, density, or frequency of the toner belt 1 can be increased. As another example, increasing the rotational speed of the rotating brush in the belt cleaner (cleaning unit) or increasing the contact pressure can also be considered.

Claims

1. An image forming apparatus, wherein: The image forming apparatus comprises: an image holding unit that holds an image formed using a developer and intended for transfer to a medium and an image not intended for transfer to a medium; a transfer unit for transferring the image to the medium; a removing unit that removes the image not intended for transfer to a medium from the image holding unit; as well as forming means for forming the image not intended for transfer to a medium on the image holding means using a developer, The forming unit has a first forming mode for a first medium and a second forming mode for a second medium having a surface roughness smaller than that of the first medium or a medium density larger than that of the first medium. The first forming mode is a mode in which, when using a predetermined first medium, the image not intended for transfer to the medium is formed before the image intended for transfer to the medium. The second forming mode is a mode for forming the image not intended for transfer to the medium between the images intended for transfer to the medium when the second medium is used. In the first forming mode, the forming unit increases the amount of developer used for forming the image not intended for transfer to a medium, as compared with the second forming mode.

2. The image forming apparatus according to claim 1, wherein The image forming apparatus includes a discriminating unit that discriminates the type of the medium.

3. The image forming apparatus according to claim 2, wherein: The image forming apparatus includes the discrimination unit configured to discriminate a medium having a surface roughness higher than a predetermined value as the first medium.

4. The image forming apparatus according to claim 2 or 3, wherein: The image forming apparatus includes the discrimination unit configured to discriminate a medium having a medium density lower than a predetermined value as the first medium.

5. The image forming apparatus according to claim 1, wherein The image forming apparatus includes the forming unit, and in the first forming mode, the forming unit forms the image not intended for transfer to a medium more frequently than in the second forming mode.

6. The image forming apparatus according to claim 1, wherein When the second medium is used, the density of the image not intended to be transferred to the medium is set to zero.

7. The image forming apparatus according to claim 1, wherein The image forming apparatus includes the forming unit capable of forming an image using developers of multiple colors, and determining the color of the developer constituting the image not intended for transfer to a medium each time the image not intended for transfer to a medium is formed.

8. The image forming apparatus according to claim 7, wherein: The image forming apparatus includes the forming unit capable of forming the image not intended for transfer to a medium using the developer of the plurality of colors whose amount of consumption has been the least.

Images