Image forming apparatus

Abstract

This invention relates to an image forming apparatus that, in film formation processes, reduces toner consumption in the toner image pattern of an image while suppressing detection errors in the adhesion detection mechanism. The image forming apparatus forms a toner image pattern, such as a scraping toner pattern (Kp), which is input to a cleaning component, such as a cleaning squeegee, used to clean the surface of an image carrier (e.g., an intermediate transfer belt), without transferring it to a recording medium. This toner image pattern is a long strip-shaped pattern in an orthogonal direction to the surface movement direction of the image carrier. Furthermore, the toner image pattern is formed by a method in which the input toner dose to a location corresponding to the placement position of the adhesion detection mechanism (e.g., an optical sensor (40F, 40C, 40R) of the cleaning component) is greater than the input toner dose to a location not corresponding to the placement position of the cleaning component.

Description

Technical Field

[0001] This invention relates to an image forming apparatus. Background Technology

[0002] This invention relates to an image forming apparatus. [Background Technology]

[0004] Conventionally, a known image forming apparatus includes an imaging mechanism for imaging a toner image, an image carrier carrying the toner image image imaged by the imaging mechanism, a transfer unit for transferring the toner image image on the image carrier to a recording medium, a cleaning unit for cleaning the surface of the image carrier, and an adhesion detection mechanism for detecting the amount of toner adhering to the toner image, which is configured to face the surface of the image carrier. The imaging mechanism forms a toner image pattern on the image carrier that is input to the cleaning unit, rather than transferring it to the recording medium.

[0005] In Patent Document 1, the aforementioned image forming apparatus describes dividing the surface of an intermediate transfer belt, which serves as an image carrier, into five regions in a direction orthogonal to the surface movement direction of the intermediate transfer belt, i.e., the belt width direction. An optical sensor, serving as an adhesion detection mechanism, is disposed in each of these regions. Then, when the optical sensor detects film formation on the surface of the intermediate transfer belt, the area of ​​the intermediate transfer belt corresponding to the optical sensor is not transferred to the recording medium; instead, a toner image pattern is formed and input to a cleaning component. Therefore, in the belt width direction, since the toner image pattern is formed only at the location where film formation has occurred, toner waste is avoided compared to the case where the toner image pattern is formed over the entire area in the belt width direction.

[0006] However, in Patent Document 1, it may not be possible to effectively suppress film formation on the image carrier.

[0007] [Patent Document 1] Japanese Patent Application Publication No. 2006-160429

[0008] [Patent Document 2] Japanese Patent Application Publication No. 09-164593

[0009] [Patent Document 3] Japanese Patent Application Publication No. 2020-121868 Summary of the Invention

[0010] To address the aforementioned issues, the present invention relates to an image forming apparatus, comprising: an imaging mechanism for imaging a toner image; an image carrier for carrying the toner image image imaged by the imaging mechanism; a transfer unit for transferring the toner image image on the image carrier to a recording medium; a cleaning unit for cleaning the surface of the image carrier; and an adhesion detection unit disposed opposite to the surface of the image carrier for detecting the amount of toner adhered to the toner image. The imaging mechanism forms a toner image pattern input to the cleaning unit onto the image carrier without transferring the toner image to the recording medium. The toner image pattern is a long strip-shaped pattern in an orthogonal direction orthogonal to the direction of movement of the image carrier surface. The imaging mechanism forms the toner image pattern such that, in the orthogonal direction, the input toner dose at a location on the cleaning unit corresponding to the location of the adhesion detection unit is greater than the input toner dose at a location on the cleaning unit not corresponding to the location of the adhesion detection unit.

[0011] According to the present invention, film formation on the image carrier can be effectively suppressed. Attached Figure Description

[0012] Figure 1 The diagram shown is a schematic configuration diagram of the image forming apparatus, namely a serial color copier, according to this embodiment.

[0013] Figure 2 The diagram shown illustrates the grayscale pattern on the intermediate transfer belt.

[0014] Figure 3 The diagram shown is an example of an image adjustment pattern formed on the intermediate transfer belt during image adjustment in parallel with the printing action.

[0015] Figure 4 The diagram shown illustrates the formation location of the toner pattern scraped off on the intermediate transfer belt.

[0016] Figure 5 The diagram shown is an example of a flowchart illustrating the formation of a pattern using toner.

[0017] Figure 6 The diagram shown is a schematic representation of an example of a scratch-off toner pattern according to this embodiment.

[0018] Figure 7 The diagram shown illustrates the width of the opposite area of ​​the pattern created by scraping off the toner.

[0019] Figure 8 The diagram shows a schematic of a reference plate used to measure the diameter of the sensor spot.

[0020] Figure 9(a) shows an example of the obtained positive reflection output, and (b) shows an example of the obtained diffuse reflection output. Detailed Implementation

[0021] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same or equivalent parts are given the same reference numerals, and detailed descriptions thereof are omitted where appropriate.

[0022] Figure 1 The diagram shown is a schematic configuration diagram of the image forming apparatus according to this embodiment, namely a serial color copier (hereinafter referred to as a copier).

[0023] exist Figure 1 In this context, a serial color copier (hereinafter referred to as a copier) that serves as an image forming apparatus includes an original transport unit 3 that transports the original to the original reading unit, an original reading unit 4 that reads the image information of the original, a paper tray 5 that loads the output image, and a paper supply unit 7 that holds the paper P, which serves as a recording medium.

[0024] Additionally, the copier 1 includes an alignment roller 9 (timing roller) for adjusting the feeding timing of paper P, and an imaging unit 10 (imaging mechanism) for forming toner images of various colors (yellow, magenta, cyan, and black). The imaging unit 10 includes, for example, photosensitive drums 11Y, 11M, 11C, and 11BK that form the toner images as latent image carriers. Furthermore, the imaging unit 10 includes a charging device 12 for uniformly charging the surfaces of each photosensitive drum 11Y, 11M, 11C, and 11BK, and a writing unit (exposure unit) 6 for emitting lasers based on input image information and writing electrostatic latent images onto each photosensitive drum 11Y, 11M, 11C, and 11BK. Additionally, a developing unit 13 is included to develop the electrostatic latent images written onto each photosensitive drum 11Y, 11M, 11C, and 11BK. It also features a primary transfer bias roller 14 to overlay and transfer the toner image formed on each photosensitive drum 11Y, 11M, 11C, 11BK onto the intermediate transfer belt 17.

[0025] Furthermore, the copier 1 includes an intermediate transfer belt 17 serving as an image carrier on which toner images of multiple colors are overlaid, and a secondary transfer roller 18 serving as a transfer unit for transferring the color toner images on the intermediate transfer belt 17 onto paper P. The copier 1 also includes a fixing unit 20 for fixing the unfixed image on the paper P, and a toner container 28 for holding various colors (yellow, cyan, magenta, and black) of toner supplied to the developing unit 13. The copier 1 further includes a belt cleaning unit 30 for removing toner (untransferred toner) adhering to the surface of the intermediate transfer belt 17. Moreover, the copier 1 includes a waste toner collection container 80 for recovering the untransferred toner removed by the belt cleaning unit 30 and the like as waste toner.

[0026] The following describes the operation of a typical color image formation process in an image forming apparatus.

[0027] First, the original document is transported from the document stage by the transport rollers of the document transport unit 3 and then placed on the contact glass of the document reading unit 4. Then, in the document reading unit 4, the image data of the original document placed on the contact glass is optically read.

[0028] In detail, the document reading unit 4 scans the image of the document on the contact glass while illuminating it with light from an illumination lamp, and images the light reflected from the document onto the color sensor via a mirror assembly and a lens. The color image data of the document is read in the color sensor according to the various color decompositions of RGB (red, green, and blue) and converted into electrical image signals. Furthermore, based on the RGB color decomposition image signals, the image processing unit performs color transformation processing, color correction processing, spatial frequency correction processing, etc., to obtain color image data in yellow, magenta, cyan, and black.

[0029] Image data of yellow, magenta, cyan, and black are received by the writing unit 6. Then, lasers L from the writing unit 6, based on the image data of each color, are directed toward the front of the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

[0030] On the other hand, the four photosensitive drums 11Y, 11M, 11C, and 11BK rotate clockwise as shown in the figure. Then, firstly, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK are uniformly charged at the points opposite to the charging device 12 (charging process). Thus, a charged potential is formed on the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK. Then, the charged surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the irradiation positions of each laser.

[0031] In the writing unit 6, lasers L corresponding to the image signals from the four light sources are emitted separately after corresponding to each color. Each laser passes through other optical paths (exposure process) according to its yellow, magenta, cyan, and black color components.

[0032] A laser beam corresponding to the yellow component is irradiated onto the surface of the first processing cartridge 11Y from the left side of the paper. At this time, the yellow component laser beam is scanned along the rotation axis (main scanning direction) of the photosensitive drum 11 by a high-speed rotating faceted mirror. Thus, an electrostatic latent image corresponding to the yellow component is formed on the surface of the photosensitive drum 11Y after it has been charged at the charging device 12.

[0033] Similarly, when the laser corresponding to the magenta component is irradiated onto the surface of the second photosensitive drum 11M from the left of the paper, an electrostatic latent image corresponding to the magenta component is formed. When the laser corresponding to the cyan component is irradiated onto the surface of the third photosensitive drum 11C from the left of the paper, an electrostatic latent image corresponding to the cyan component is formed. When the laser corresponding to the black component is irradiated onto the surface of the fourth photosensitive drum 11BK from the left of the paper, an electrostatic latent image corresponding to the black component is formed.

[0034] Subsequently, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK, which have formed electrostatic latent images of various colors, reach positions facing the developing apparatus 13. Then, toners of various colors are supplied from the developing apparatus 13 to the photosensitive drums 11Y, 11M, 11C, and 11BK, and the latent images on the photosensitive drums 11Y, 11M, 11C, and 11BK are developed (developing process).

[0035] After the developing process, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach the opposing portions of the intermediate transfer belt 17, which serves as the image carrier. Here, in each opposing portion, a primary transfer bias roller 14 is disposed abutting against the inner circumferential surface of the intermediate transfer belt 17. Then, at the position of the primary transfer roller 14, the toner images of each color formed on the photosensitive drums 11Y, 11M, 11C, and 11BK are sequentially and overlappingly transferred onto the intermediate transfer belt 17 in one step (one-step transfer process).

[0036] After the transfer process, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK reach positions facing the cleaning section 15. Then, at the cleaning section 15, any untransferred toner remaining on the photosensitive drums 11Y, 11M, 11C, and 11BK is removed and recycled (cleaning process). Additionally, the untransferred toner removed and recycled by the cleaning section 15 is transported as waste toner to the waste toner recycling container 80 via a transport path for recycling. Afterward, the surfaces of the photosensitive drums 11Y, 11M, 11C, and 11BK pass through the static elimination section, thus completing the series of imaging processes for the photosensitive drums 11Y, 11M, 11C, and 11BK.

[0037] On the other hand, the various toners on the photosensitive drum 11 overlap and are then transferred (carried) by the intermediate transfer belt 17 (image carrier) in a single transfer. Figure 1 After moving counterclockwise, it reaches a position opposite to the secondary transfer roller 18. The secondary transfer roller 18 abuts against the intermediate transfer belt 17, forming a secondary transfer clamping part as a transfer clamping part. In this secondary transfer clamping part, the colored toner carried on the intermediate transfer belt 17 is transferred onto the paper P in a secondary transfer (secondary transfer process).

[0038] A secondary transfer bias voltage is applied to the opposing roller 18A, which is opposite to the secondary transfer roller 18 via the intermediate transfer belt 17, and the secondary transfer roller 18 is electrically grounded. When the colored toner image of the intermediate transfer belt 17 is transferred to the paper P, a transfer bias voltage of the normal charged polarity (i.e., negative polarity) of the toner is applied to the opposing roller 18A, and the negative polarity normal charged toner on the intermediate transfer belt is transferred to the paper P through repulsive force.

[0039] After the secondary transfer process, the surface of the intermediate transfer belt 17 reaches the position of the belt cleaning device 30. The belt cleaning device 30 has a cleaning scraper 31 as a cleaning component. The cleaning scraper 31 removes the toner (untransferred toner) adhering to the intermediate transfer belt 17. The toner removed by the cleaning scraper is transported as waste toner to the waste toner recycling container 80 for recycling via a conveying path.

[0040] Here, the paper P, which is conveyed between the intermediate transfer belt 17 and the secondary transfer roller 18 (secondary transfer clamping section), is conveyed from the paper supply section 7 via the alignment roller 9 and the like.

[0041] In detail, starting from the paper feeding section 7 that holds the paper P, the sheet P supplied by the paper feeding roller 8 is guided to the alignment roller 9 after passing through the transport guide section. When the paper P reaches the alignment roller 9, it is aligned and then transported toward the secondary transfer clamping section.

[0042] After the full-color image is transferred to the paper P in the secondary transfer process, it is guided to the fixing unit 20. In the fixing unit 20, the color image is fixed onto the paper P at the clamping point of the fixing roller and the pressure roller. Then, the paper P after the fixing process is discharged from the unit body as an output image by the paper discharge roller and stacked on the paper discharge tray 5, thus completing the series of image forming processes.

[0043] In this copier, in order to stabilize image quality under environmental changes or over time, a control called "process control" is implemented at specified times.

[0044] Figure 2 The diagram shown illustrates the grayscale pattern on the intermediate transfer belt.

[0045] The grayscale pattern is composed of multiple toner patches with different image concentrations, formed on the central transfer belt 17 at positions opposite to the optical sensor unit 40 (center and both ends in the width direction). Figure 2 In the example shown, grayscale patterns PK, PC, PM, and PY are formed from top to bottom, consisting of black, cyan, magenta, and yellow.

[0046] The optical sensor unit 40 has a plurality of optical sensors 40R, 40C, and 40F arranged at predetermined intervals along the width direction of the intermediate transfer belt 17, serving as adhesion amount detection mechanisms. Each optical sensor outputs a signal corresponding to the light reflectance of the intermediate transfer belt 17 or the grayscale patterns PK, PC, PM, and PY on the intermediate transfer belt 17, and detects the toner adhesion amount. The copier 1 adjusts imaging conditions such as the developing bias voltage Vb based on the detected toner adhesion amount.

[0047] Optical sensors 40R and 40F, positioned opposite the width-direction end region of the intermediate transfer belt 17, are located on the outer side of the area passing through the paper. Therefore, as... Figure 3 As shown, in the toner image formation process transferred onto paper, an image adjustment pattern is formed on the outer side of the paper area, and the amount of toner adhering to this image adjustment pattern is detected by optical sensors 40R and 40F. Then, based on the amount of toner adhering detected by the optical sensors 40R and 40F, the image density can be adjusted by adjusting the developing bias voltage, etc.

[0048] The base component of the toner, silica or titanium dioxide added to the toner, and other so-called toner additives are transferred from the photosensitive drum 11 to the intermediate transfer belt 17. The toner additives transferred to the intermediate transfer belt 17 adhere to it, sometimes forming a film on the intermediate transfer belt 17. Furthermore, in the case of a lubricant coating section that applies lubricant to the surface of the photosensitive drum 11, various components contained in the lubricant, in addition to the toner additives, are also transferred from the photosensitive drum 11 to the intermediate transfer belt 17. Then, the interaction between the toner additives and the lubricant sometimes leads to deterioration of the film formation on the intermediate transfer belt 17. Furthermore, in the secondary transfer clamping section, paper dust is transferred from the paper P to the intermediate transfer belt 17 and adheres to it, sometimes resulting in paper dust film formation.

[0049] The film formation on the intermediate transfer belt 17 is achieved through external pressure on the intermediate transfer belt 17 (mainly the contact pressure with the photosensitive drum), resulting in the adhesion of film-forming substances such as toner additives like silica and various components contained in the lubricant. If a full-solid or halftone image is output during film formation on the intermediate transfer belt 17, and no toner is present in the area corresponding to the film formation, abnormal images such as white spots or other defects will occur.

[0050] Furthermore, the gloss of the belt decreases during film formation. Therefore, when film formation occurs in the area of ​​the intermediate transfer belt 17 opposite to the optical sensors 40R, 40C, and 40F, the output signal changes, making it difficult to accurately detect the amount of grayscale pattern adhered to the intermediate transfer belt. Additionally, due to the unevenness of the film formation, there is also a problem of unstable output from the optical sensors, preventing accurate image adjustment.

[0051] Furthermore, the cleaning performance of the cleaning blade 31 may decrease due to film formation. In the belt width direction, there is a higher chance of inputting grayscale patterns with a high adhesion per unit area at positions corresponding to the configuration of the cleaning blade 31 and the optical sensors 40R, 40C, and 40F. Therefore, when film formation occurs in the area of ​​the intermediate transfer belt 17 opposite to the optical sensors 40R, 40C, and 40F, the risk of poor cleaning (toner leakage) when the grayscale pattern is input onto the cleaning blade 31 increases.

[0052] The aforementioned film is scraped off by the toner retained on the contact area between the cleaning blade 31 and the intermediate transfer belt 17 (hereinafter referred to as the "cleaning area"), and can be removed from the surface of the intermediate transfer belt 17. Specifically, the film on the surface of the intermediate transfer belt is scraped off by the unevenness of the toner surface retained on the cleaning area and the pressure applied to the toner by the cleaning blade 31.

[0053] Therefore, in order to suppress film formation on the intermediate transfer belt 17, this copier 1 forms a scratch-off toner pattern on the intermediate transfer belt 17 at a predetermined time. Then, by inputting the scratch-off toner pattern into the cleaning blade 31, a sufficient amount of toner is retained on the cleaning area.

[0054] Figure 4 The diagram shown illustrates the formation location of the toner pattern scraped off on the intermediate transfer belt.

[0055] Figure 4 This refers to the case where three sheets are printed consecutively using the usual image forming process. For example... Figure 4 As shown, the locations where the pattern is formed using scratch-off toner can be listed below.

[0056] 1. Positioned further forward than the first sheet of paper facing the secondary transfer clamp.

[0057] 2. A position further outwards than the width of the paper passing through the secondary transfer clamping section.

[0058] 3. The position of the non-image forming area at the rear end of the paper in the secondary transfer clamping section.

[0059] 4. The position between the sheets of paper

[0060] 5. The final position of the paper after passing through the secondary transfer clamp.

[0061] Regarding point 3 above, the location can also be in the non-image forming area at the front end of the paper in the secondary transfer clamping section. When the scratch-off toner pattern on the intermediate transfer belt passes through the secondary transfer clamping section, a positive bias is applied to the opposing roller 18A. By applying a positive bias to the opposing roller 18A, the scratch-off toner pattern is electrostatically attracted to the intermediate transfer belt 17, preventing the scratch-off toner pattern from being transferred to the secondary transfer roller 18 or the paper P.

[0062] Figure 5 The diagram shown is an example of a flowchart illustrating the formation of the aforementioned scratch-off toner pattern.

[0063] After the control unit receives the printing instruction and starts driving the intermediate transfer belt 17, it begins measuring the travel distance of the intermediate transfer belt 17 (S1). When the driving of the intermediate transfer belt 17 stops, the necessary amount of toner input to the cleaning squeegee 31 is calculated based on the film formation state on the surface of the intermediate transfer belt 17 according to the measured travel distance of the intermediate transfer belt 17. Specifically, the necessary amount of toner input is calculated by multiplying the travel distance of the intermediate transfer belt 17 by a coefficient. Then, the calculated necessary amount of toner input is added together to calculate the cumulative value of the necessary amount of toner input (S2). When the cumulative value exceeds a threshold (S3), a toner pattern for scraping off is formed on the next drive of the intermediate transfer belt 17. Then, the toner dosage of the formed toner pattern for scraping off (the toner dosage input to the cleaning squeegee) is subtracted from the cumulative value (S4).

[0064] When forming a scratch-off toner pattern by detecting the presence or absence of film formation using an optical sensor, even if film formation occurs outside the detection range of the optical sensor, the film formation outside the area opposite the optical sensor on the intermediate transfer belt is not removed before film formation occurs in the area opposite the optical sensor on the intermediate transfer belt. As a result, it may not be possible to effectively suppress the occurrence of abnormal images such as white spots caused by film formation.

[0065] In contrast, in this embodiment, the scratch-off toner pattern is formed based on the travel distance of the intermediate transfer belt 17. Therefore, even if film formation does not occur in the area of ​​the intermediate transfer belt opposite the optical sensor, but film formation may occur in other areas, a scratch-off toner pattern is still formed. Thus, compared to the case where the scratch-off toner pattern is formed based on the detection results of the optical sensor, film formation on the intermediate transfer belt can be removed more effectively.

[0066] The aforementioned coefficients can be fixed values, or they can be varied, for example, between color and monochrome image modes. This is because film formation can sometimes deteriorate in color image mode compared to monochrome image mode. In color image mode, the internal temperature tends to be higher due to the higher fixing setting temperature and increased number of motor stages compared to monochrome image mode. This higher internal temperature increases the amount of slip on the cleaning blade 31, potentially worsening film formation. Furthermore, in the case of a lubricant coating section that applies lubricant to the surface of the photosensitive drum 11, the amount of lubricant used to form the film-forming material adhering to the intermediate transfer belt 17 increases in color image mode compared to monochrome image mode. Therefore, film formation may deteriorate in color image mode compared to monochrome image mode.

[0067] Therefore, for example, the coefficient B for the color image mode is set to a higher value than the coefficient A for the monochrome image mode (A < B). Then, during image formation (when the intermediate transfer belt is driven), it is determined whether it is a monochrome image mode or a color image mode. In monochrome image mode, coefficient A is used to calculate the necessary toner input amount, while in color image mode, coefficient B is used to calculate the necessary toner input amount.

[0068] For example, in the case of multiple color image modes, as mentioned above, the possibility of film formation deterioration is higher than in monochrome image modes. However, in the case of multiple color image modes, since the cumulative value of the necessary toner input exceeds the threshold during the short travel distance of the intermediate transfer belt 17, the formation of the toner pattern for scraping is performed at an earlier time. On the other hand, in the case of multiple monochrome image modes, film formation is less likely to deteriorate compared to color image modes. Therefore, in the case of multiple monochrome image modes, the travel distance during which the cumulative value of the necessary toner input exceeds the threshold becomes longer, and the formation of the toner pattern for scraping is performed at a later time.

[0069] In this way, by forming the scratch-off toner pattern based on the image pattern, the scratch-off toner pattern can be formed at the appropriate time, which can effectively suppress unnecessary toner consumption and film deterioration.

[0070] Conventionally, a method was used to maintain a constant input toner dosage to the cleaning squeegee 31 in the width direction, forming a long, strip-shaped toner pattern in the width direction to suppress film formation on the intermediate transfer belt. However, while this method effectively suppressed abnormal images such as white spots caused by film formation, it could not sufficiently suppress the decrease in adhesion detection accuracy of the optical sensors 40R, 40C, and 40F due to film formation. This is believed to be because the impact of film formation is greater than that of abnormal images such as white spots caused by film formation; even a small amount of film formation can reduce adhesion detection accuracy.

[0071] Therefore, in this embodiment, a strip-shaped toner pattern for scraping is formed. That is, a toner pattern for scraping is formed such that the input toner dose on the cleaning scraper 31 in the opposing area opposite to the optical sensors 40R, 40C, 40F is greater than the input toner dose in the non-opposing area not opposite to the optical sensors 40R, 40C, 40F.

[0072] Figure 6 The diagram shown is a schematic representation of an example of a scratch-off toner pattern according to this embodiment.

[0073] like Figure 6 (a) Figure 6 As shown in (b), the toner pattern Kp for scraping off is a strip-shaped pattern having a length from the optical sensor 40F at one end to the optical sensor 40R at the other end in the width direction, and having a length of more than the paper-passing area T of the intermediate transfer belt 17. Therefore, the film formed in the paper-passing area T carrying the toner image transferred to the intermediate transfer belt 17 can be removed, and abnormal images such as white spots caused by film formation can be suppressed.

[0074] Then, in Figure 6 In (a), the length of the intermediate transfer belt 17 in the surface movement direction of the area P1 opposite to the optical sensors 40R, 40C, and 40F of the scraped toner pattern Kp is longer than the length of the non-opposite area P2 in the surface movement direction. Therefore, in the belt width direction, the input toner dosage at the location corresponding to the arrangement position of the cleaning blade 31 and the optical sensors 40R, 40C, and 40F is greater than the input toner dosage at other locations.

[0075] In addition, such as Figure 6 As shown in (b), it is also possible to have a greater amount of toner adhered to the opposite area P1 of the toner pattern Kp being scraped off than toner adhered to the non-opposite area P2. Even in Figure 6In (b), in the width direction, the input toner dose input to the part corresponding to the configuration position of the cleaning scraper 31 and the optical sensors 40R, 40C, 40F can also be more than the input toner dose input to other parts.

[0076] In the width direction, by increasing the input toner dosage to the portion corresponding to the configuration positions of the cleaning squeegee 31 and the optical sensors 40R, 40C, and 40F, the toner can remain at the cleaning position of the cleaning squeegee for a longer period. This improves the toner's removal effect on the film formed on the intermediate transfer belt. As a result, the film formed in the area opposite the intermediate transfer belt 17 and the optical sensors 40R, 40C, and 40F can be effectively removed, and the reduction in the detection accuracy of the toner adhesion amount can be suppressed.

[0077] On the other hand, the input toner dosage at locations other than those corresponding to the positions of the cleaning scraper 31 and the optical sensors 40R, 40C, and 40F (hereinafter referred to as non-corresponding locations) is less than that at locations corresponding to the positions of the optical sensors 40R, 40C, and 40F. For non-corresponding locations, it is sufficient to remove the film on the intermediate transfer belt to a level that does not produce abnormal images such as white spots caused by film formation. Compared to the decrease in detection accuracy of toner adhesion caused by film formation, the impact of film formation on abnormal images such as white spots is lower. Therefore, even if there is some film residue on the intermediate transfer belt, abnormal images such as white spots caused by film formation can be suppressed. Therefore, even with a low input toner dosage, the film on the intermediate transfer belt can be reduced to a level that does not produce abnormal images such as white spots caused by film formation.

[0078] Thus, in this embodiment, by making the input toner dosage of the scraping toner pattern to the cleaning squeegee 31 different in the width direction, compared with the case where the amount is the same in the width direction, unnecessary toner consumption can be suppressed for the input toner dosage to the cleaning squeegee 31, the generation of abnormal images can be suppressed and the detection accuracy of toner adhesion amount can be reduced.

[0079] In Patent Document 1, where the intermediate transfer belt 17 is divided into multiple regions along its width, and a toner pattern for scraping is formed only in the divided regions when film formation occurs, an optical sensor needs to be configured in each region to detect the presence or absence of film formation in each region. In contrast, in this embodiment, the toner pattern for scraping is set as a long strip-shaped pattern along the width, and toner is fed into the cleaning squeegee across the entire width. As a result, film formation can be removed across the entire width. Therefore, unlike Patent Document 1, it is not necessary to detect which region of the intermediate transfer belt 17 has formed film in the width direction using an optical sensor. This prevents the situation where film formation outside the detection range of the optical sensor is not removed if film formation does not occur within the detection range of the optical sensor. Therefore, compared to Patent Document 1, film formation can be removed more effectively.

[0080] In this embodiment, the input color tone dose input to the cleaning blade 31 at the location corresponding to the configuration positions of the optical sensors 40R, 40C, and 40F is twice the input color tone dose input to non-corresponding locations. It should be noted that the difference between the input color tone dose input to the cleaning blade 31 at the location corresponding to the configuration positions of the optical sensors 40R, 40C, and 40F and the input color tone dose input to non-corresponding locations can also be appropriately determined depending on the configuration of the device.

[0081] Alternatively, it can be to Figure 6 (a) and Figure 6 (b) The combined toner pattern Kp for scraping. That is, the amount of toner adhering to the opposing region P1 is greater than the amount of toner adhering to the non-opposing region P2, and the length of the surface movement direction of the intermediate transfer belt 17 in the opposing region P1 is greater than the length of the surface movement direction of the non-opposing region P2. Even with this configuration, the input toner dosage to the location corresponding to the configuration position of the cleaning blade 31 and the optical sensors 40R, 40C, 40F can be greater than the input toner dosage to other locations.

[0082] Figure 7 The diagram shown illustrates the width of the opposite area P1 of the scratched toner pattern Kp.

[0083] The width of the opposing region P1 of the scratch-off toner pattern Kp is set to the size of the lens 40a of the optical sensor, and is also set to the detection range of the optical sensor, i.e., above the sensor spot diameter. Therefore, the film formed within the detection range of the optical sensor, at least the intermediate transfer belt 17, can be effectively removed by the input toner fed to the cleaning squeegee. This suppresses the decrease in the detection accuracy of the toner adhesion amount on the optical sensor. Furthermore, by setting the width of the opposing region P1 of the scratch-off toner pattern Kp to the size of the lens 40a of the optical sensor, unnecessary waste of toner can be suppressed compared to cases where the width exceeds the size of the lens 40a.

[0084] Furthermore, in this embodiment, an optical sensor is used that includes a light-receiving element for receiving diffuse light and a light-receiving element for receiving orthogonal light. Thus, the optical sensor, which receives both orthogonal and diffuse light, has two types of light spot diameters: an orthogonal light spot diameter and a diffuse light spot diameter. The width of the opposite region P1 of the toner pattern Kp being scraped off is wider than both the orthogonal light spot diameter and the diffuse light spot diameter.

[0085] Here, the measurement of the sensor spot diameter of the optical sensor is explained.

[0086] Figure 8 The figure shows a reference plate 100 used in measuring the diameter of the sensor spot. The upper part of the figure is a glass positive reflective substrate 100a, and the lower part of the figure is a resin diffuse reflective substrate 100b with a roughened surface.

[0087] With the measurement range of the reference plate facing the optical sensor, scan downwards in the image at intervals of 0.1 mm, starting from the measurement range +5 mm, to obtain the orthographic reflection output VO1 and diffuse reflection output VO2.

[0088] Figure 9 (a) shows an example of a positive reflection output VO1. Figure 9 (b) shows an example of the diffuse reflection output VO2 obtained. The horizontal axis in the figure is the distance from the boundary between the positive reflection substrate 100a and the diffuse reflection substrate 100b of the reference plate 100, with positive values ​​on the positive reflection substrate side and negative values ​​on the diffuse reflection substrate side.

[0089] from Figure 9(a) It can be seen that when the entire orthoreflection spot is located in the orthoreflection substrate 100a, the orthoreflection output VO1 of the optical sensor shows its maximum value VO1(max). Then, when scanning the reference plate 100, a portion of the orthoreflection spot enters the diffuse reflection substrate 100b. As a result, the orthoreflection output VO1 decreases. When scanning the reference plate 100 further, the proportion of the orthoreflection spot in the diffuse reflection substrate 100b increases, and correspondingly, the orthoreflection output VO1 decreases. Then, when the entire orthoreflection spot enters the diffuse reflection substrate 100b, the orthoreflection output VO1 shows its minimum value VO1(min).

[0090] On the other hand, from Figure 9 (b) It can be seen that when the entire diffuse reflection spot is located in the positive reflection substrate 100a, the diffuse reflection output VO2 of the optical sensor exhibits a minimum value VO2(min). Then, by scanning the reference plate and allowing a portion of the diffuse reflection spot to enter the diffuse reflection substrate 100b, the diffuse reflection output VO2 gradually increases. Finally, when the entire diffuse reflection spot enters the diffuse reflection substrate 100b, the diffuse reflection output VO2 exhibits a maximum value VO2(max).

[0091] The calculation of the diameter φVO1(D) of the orthogonal reflection spot first involves calculating the orthogonal reflection substrate portion 100a of the detection reference plate 100. Figure 9 The maximum positive reflection output VO1(max) is calculated by averaging ten points in the area (+5.0 to +4.0 mm) indicated by the dashed line X1 in (a). Next, the diffuse reflection substrate portion 100b of the detection reference plate 100 is calculated. Figure 9 The minimum positive reflection output VO1(min) is calculated by taking the average of ten points in the area (-4.0 to -5.0 mm) shown by the dashed line X2 in (a).

[0092] Next, calculate the initial distance PVO1(D1) where the output of the orthorhombic reflected light is less than or equal to (VO1(m3x)-VO1(min))×0.9+VO1(min). Also, calculate the initial distance PVO1(D2) where the output of the orthorhombic reflected light is less than or equal to (VO1(max)-VO1(min))×0.1+VO1(min). Then, calculate the diameter φVO1(D) of the orthorhombic reflected light spot according to Equation 1 below.

[0093] φVO1(D)=|PVO1(D1)-PVO1(D2)| (Formula 1)

[0094] The calculation of the diffuse reflection spot diameter φVO2(D) is basically the same as the calculation of the orthographic reflection spot diameter. That is, firstly, the orthographic reflection substrate portion 100a of the detection reference plate 100 is calculated. Figure 9(b) The minimum diffuse reflection output VO2(min) is calculated by averaging ten points in the area (+5.0 to +4.0 mm) indicated by the dashed line Y2. Next, the diffuse reflection substrate portion 100b of the detection reference plate 100 is calculated. Figure 9 (b) The ten-point average of the area (-4.0 to -5.0 mm) shown by the dashed line Y1 is used to calculate the maximum diffuse reflection output VO2(max).

[0095] Next, the initial distance PVO2(D1) for diffuse reflection light output less than (VO2(m3x)-VO2(min))×0.1+VO2(min) is calculated. Additionally, the initial distance PVO1(D2) for diffuse reflection light output less than (VO2(max)-VO2(min))×0.9+VO2(min) is calculated. Then, the diffuse reflection spot diameter φVO2(D) is calculated using Equation 2 below.

[0096] φVO2(D)=|PVO2(D1)-PVO2(D2)| (Formula 2)

[0097] Furthermore, while the above description describes an embodiment of an image forming apparatus using an intermediate transfer method, the present invention can also be applied to a direct transfer image forming apparatus that directly transfers a toner image from a photosensitive drum to paper, which serves as the recording medium. In this direct transfer image forming apparatus, the image carrier corresponds to the photosensitive drum, and the transfer component corresponds to a transfer roller that abuts against the photosensitive drum to form a transfer clamping portion. Then, the cleaning component corresponds to a photosensitive cleaning blade that cleans the surface of the photosensitive component.

[0098] The above explanation is just one example; the various methods below each have their own unique effects.

[0099] (Method 1)

[0100] An image forming apparatus includes an imaging mechanism (in this embodiment, comprising a photosensitive drum 11, a charging device 12, a writing unit (exposure unit) 6, and a developing device 13, etc.) for imaging a toner image, an image carrier such as an intermediate transfer belt 17 carrying the toner image image imaged by the imaging mechanism, a transfer unit such as a secondary transfer roller 18 for transferring the toner image on the image carrier to a recording medium such as paper P, a cleaning unit such as a cleaning blade 31 for cleaning the surface of the image carrier, and an optical sensor disposed opposite to the surface of the image carrier for detecting the amount of toner adhering to the toner image. The adhesion detection mechanism of the device, etc., and the imaging mechanism form a toner image pattern, such as a scraping toner pattern Kp, input to the cleaning component on the image carrier without transferring it to the recording medium. The toner image pattern is a long strip pattern in an orthogonal direction orthogonal to the surface movement direction of the image carrier. The imaging mechanism forms the toner image pattern such that, in the orthogonal direction, the input toner dose at the part of the cleaning component corresponding to the position of the adhesion detection mechanism is greater than the input toner dose at the part of the cleaning component that does not correspond to the position of the attachment detection mechanism.

[0101] In Patent Document 1, the method of dividing the surface of an image carrier into multiple regions along the aforementioned orthogonal direction and arranging an adhesion detection mechanism such as an optical sensor in each divided region, and forming a toner image pattern in the region corresponding to the optical sensor after the adhesion detection mechanism detects film formation, has the following problem. That is, film formation outside the detection range of the adhesion detection mechanism on the image carrier surface is not removed before film formation within the detection range of the adhesion detection mechanism, thus resulting in the inability to effectively suppress film formation in the bandwidth direction.

[0102] In contrast, in Method 1, the toner image pattern is a long strip pattern in an orthogonal direction orthogonal to the surface movement direction of the image carrier. Toner is applied to the cleaning component across the entire area in this orthogonal direction, thereby removing the film from the entire area in the orthogonal direction. Therefore, unlike Patent Document 1, film formation is not detected in areas segmented in the orthogonal direction using optical sensors or the like. Instead, the strip pattern can be formed at the point where film formation is likely, based on factors such as the moving distance of the image carrier. Thus, compared to Patent Document 1, which uses multiple adhesion detection mechanisms to detect areas where film formation has occurred and forms the toner pattern only in those areas, film formation can be effectively suppressed.

[0103] Furthermore, in Method 1, as described in the embodiment, by inputting the toner image pattern into the cleaning member, the toner is retained at the contact portion of the cleaning member with the image carrier, and the retained toner can be used to scrape off the film formed on the image carrier. This suppresses abnormal images such as white spots caused by film formation.

[0104] Furthermore, the input toner dosage is increased when applied to the area corresponding to the placement of the adhesion detection mechanism on the cleaning component compared to the input toner dosage applied to areas not corresponding to the placement of the cleaning component. As a result, the toner remains in the corresponding area for a longer period, allowing for longer film removal compared to non-corresponding areas. Consequently, film formation in the opposing area (where the adhesion detection mechanism faces away) can be removed compared to the non-opposing area of ​​the image carrier. This results in less film formation in the opposing area compared to the non-opposing area, and effectively suppresses the detection error of the adhesion detection mechanism, which is more susceptible to film formation than image anomalies caused by film formation.

[0105] Furthermore, compared to the case where the input toner dosage of the toner image pattern is constant and input to the cleaning component in a direction perpendicular to the surface movement direction of the image carrier, the toner consumption of the toner image pattern can be reduced while suppressing the detection error of the adhesion detection mechanism.

[0106] (Method 2)

[0107] In Method 1, the length of the first region, such as the opposite region P1 of the toner image pattern Kp for toner scraping, is longer than the length of the surface movement direction of the image carrier, such as the intermediate transfer belt 17, in the direction corresponding to the configuration position of the cleaning component, such as the cleaning scraper 31, and the position corresponding to the configuration position of the adhesion detection mechanism, such as the optical sensor.

[0108] Therefore, if used Figure 6 As explained in (a), the input toner dose can be greater at the location corresponding to the position of the adhesion detection mechanism such as the optical sensor of the cleaning component such as the cleaning scraper 31 than at the location not corresponding to the position of the cleaning component.

[0109] (Method 3)

[0110] In Method 1 or Method 2, the toner dosage of a first region, such as the opposite region P1 of the toner image pattern Kp for toner scraping, is greater than the toner dosage outside the first region when the position of the cleaning component, such as the cleaning scraper 31, corresponding to the position of the attachment amount detection mechanism, such as the optical sensor, is input to the part of the cleaning component.

[0111] Therefore, if used Figure 6As explained in (b), the input toner dose can be greater at the location corresponding to the position of the adhesion detection mechanism such as the optical sensor of the cleaning component 31 than at the location not corresponding to the position of the cleaning component.

[0112] (Method 4)

[0113] In any of Modes 1 to 3, a first region, such as P1, which is opposite to the toner image pattern Kp for toner scraping, is input to the cleaning component such as the cleaning scraper 31 at the location corresponding to the placement position of the adhesion detection mechanism such as the optical sensor. This first region is above the adhesion detection range of the adhesion detection mechanism.

[0114] Therefore, if used Figure 7 As explained, the film formed within the detection range of the adhesion amount detection mechanism of the image carrier such as the intermediate transfer belt 17 can be effectively removed by the input toner fed to a cleaning component such as a cleaning squeegee. This suppresses any decrease in the toner adhesion amount detection accuracy of the adhesion amount detection mechanism.

[0115] (Method 5)

[0116] In Method 4, the adhesion detection mechanism is an optical sensor, and the adhesion detection range is the spot diameter of the optical sensor.

[0117] (Method 6)

[0118] In any of the methods 1 to 5, multiple adhesion detection mechanisms such as optical sensors are arranged in a direction orthogonal to the surface movement direction of the image carrier such as the intermediate transfer belt 17, and at least one of the adhesion detection mechanisms is arranged outside the recording medium of the image carrier through the paper area.

[0119] Therefore, if used Figure 3 As explained, in the toner image formation process transferred onto the recording medium, an image adjustment pattern can be formed. The amount of toner adhering to this image adjustment pattern is detected by an adhesion detection mechanism, and image adjustments such as image density are performed.

Claims

1. An image forming apparatus, comprising: Imaging mechanism, used to image the toner image; An image carrier that carries a toner image imaged by the imaging mechanism; The transfer unit transfers the toner image on the image carrier to the recording medium; Cleaning components clean the surface of the image carrier, and An adhesion detection mechanism is disposed facing the surface of the image carrier to detect the amount of toner adhered to the toner image. The imaging mechanism forms the toner image pattern input to the cleaning component onto the image carrier without transferring it onto the recording medium. The toner image pattern is a long strip pattern in an orthogonal direction to the surface movement direction of the image carrier. The imaging mechanism forms the toner image pattern such that, in the orthogonal direction, the input toner dose to the part of the cleaning component corresponding to the configuration position of the adhesion detection mechanism is greater than the input toner dose to the part of the cleaning component that does not correspond to the configuration position. The first area of ​​the toner-image pattern into which the toner is input to the cleaning component at the location corresponding to the position of the adhesion detection mechanism is above the adhesion detection range of the adhesion detection mechanism.

2. The image forming apparatus according to claim 1, characterized in that: The length of a first region of the toner image pattern input to the cleaning component at the location corresponding to the placement position of the adhesion detection mechanism is longer than the length of the region outside the first region in the surface movement direction.

3. The image forming apparatus according to claim 1, characterized in that: The toner dosage of the first region of the toner image pattern input to the cleaning component at the location corresponding to the placement position of the adhesion detection mechanism is greater than the toner dosage outside the first region.

4. The image forming apparatus according to claim 2, characterized in that: The toner dosage of the first region of the toner image pattern input to the cleaning component at the location corresponding to the placement position of the adhesion detection mechanism is greater than the toner dosage outside the first region.

5. The image forming apparatus according to claim 1, characterized in that: The adhesion detection mechanism is an optical sensor, and the adhesion detection range is the spot diameter of the optical sensor.

6. The image forming apparatus according to any one of claims 1 to 5, characterized in that: Multiple adhesion detection mechanisms are arranged in a direction orthogonal to the surface movement direction of the image carrier, and at least one of the adhesion detection mechanisms is arranged outside the recording medium of the image carrier through the paper area.

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