Image forming apparatus

Abstract

This design avoids problems that may occur when a decrease in the lubricant supply means results in areas of lubrication failure on the intermediate transfer body where lubricant is not supplied via the opposing member of the intermediate transfer body. [Solution] An image forming apparatus equipped with a toner input control means that forms a toner image on a surface area of ​​the image carrier (1) where no image has been formed, transfers the toner image to an intermediate transfer body (8), and inputs it to the contact area of ​​a cleaning member (31), is provided with a determination means (302) to determine whether or not a non-supply area (A) has occurred on the intermediate transfer body (8) due to a decrease in lubricant in the lubricant supply means (13) and lubricant is not supplied via the intermediate transfer body opposing members (8, 19). When the determination means (302) determines that a non-supply area (A) has occurred (No in step 3), the toner input control means (300) increases the amount of toner that enters the contact area of ​​the cleaning member (31) compared to before it was determined that a non-supply area (A) had occurred.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus.

Background Art

[0002] Conventionally, an image forming apparatus has been known that includes an image carrier on which a toner image of an image to be formed is formed, an intermediate transfer member to which the toner image on the image carrier is transferred, a transfer member that transfers the toner image on the intermediate transfer member to a recording medium, a cleaning member that cleans the surface of the intermediate transfer member after the toner image has been transferred to the recording medium, a lubricant supply means that supplies a lubricant to an intermediate transfer member facing member that faces the intermediate transfer member such as the image carrier, and a toner input control means that forms a toner image on a surface portion of the image carrier where no image is formed, transfers the toner image to the intermediate transfer member, and inputs it to the contact portion of the cleaning member.

[0003] For example, Patent Document 1 describes an image forming apparatus in which a lubricant is supplied to at least one of an image carrier as an intermediate transfer member facing member and a transfer member by a lubricant supply means, and the lubricant supplied to at least one of the image carrier and the transfer member is indirectly supplied to the intermediate transfer member. In this image forming apparatus, the amount of toner input to the contact portion of the cleaning member is changed so as to be larger when in an image forming mode in which there is less opportunity for the lubricant to be indirectly supplied to the intermediate transfer member from either one or both of the image carrier or the transfer member, compared to when in an image forming mode in which there is more opportunity for the lubricant to be indirectly supplied.

Summary of the Invention

Problems to be Solved by the Invention

[0004] There remains a problem of avoiding a malfunction when a non - supply portion where the lubricant is not supplied via the intermediate transfer member facing member occurs on the intermediate transfer member due to a decrease in the lubricant of the lubricant supply means.

Means for Solving the Problems

[0005] To solve the above-mentioned problems, the present invention provides an image forming apparatus comprising: an image carrier on which a toner image of an image to be formed is formed; an intermediate transfer body on which the toner image of the image carrier is transferred; a transfer member for transferring the toner image of the intermediate transfer body to a recording medium; a cleaning member for cleaning the surface of the intermediate transfer body after the toner image has been transferred to the recording medium; a lubricant supply means for supplying lubricant to an intermediate transfer body opposing member facing the intermediate transfer body, such as the image carrier; and a toner input control means for forming a toner image on a surface portion of the image carrier where the image has not been formed, transferring the toner image to the intermediate transfer body, and inputting it to the contact portion of the cleaning member. The present invention provides a determination means for determining whether or not a non-supply area has occurred on the intermediate transfer body due to a decrease in lubricant in the lubricant supply means, and the toner input control means is characterized in that, when the determination means determines that a non-supply area has occurred, it increases the amount of toner to enter the contact portion of the cleaning member compared to before it determined that a non-supply area had occurred. [Effects of the Invention]

[0006] According to the present invention, it is possible to avoid problems that occur when a decrease in the lubricant supply means results in a supply failure in the intermediate transfer body where lubricant is not supplied via the intermediate transfer body opposing member. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of the copier according to this embodiment. [Figure 2] A close-up diagram of the copier. [Figure 3] A schematic diagram illustrating the grayscale pattern on the intermediate transfer belt of the copier. [Figure 4] An explanatory diagram of the grayscale pattern sensor in the copier. [Figure 5] A diagram illustrating the input toner pattern of the copier. [Figure 6] A flowchart illustrating the formation of the input toner pattern for the copier. [Figure 7] Diagram illustrating an example of the input toner pattern for the copier. [Figure 8] Diagram illustrating other examples of input toner patterns for the same copier. [Figure 9] A flowchart for creating the input toner pattern for the copier. [Figure 10] Diagram explaining the solid lubricant for the copier. [Figure 11] An illustration illustrating the depletion of the solid lubricant in the photocopier. [Figure 12] This diagram illustrates the input toner pattern for blade peeling caused by lubrication depletion in the copier. [Figure 13] A diagram illustrating a modified version of the input toner pattern of the same copier. [Figure 14] Block diagram of the copier. [Figure 15] Flowchart of the copier. [Modes for carrying out the invention]

[0008] The following describes an embodiment of a tandem-type color copier (hereinafter referred to as "copier 500") as an image forming apparatus to which the present invention can be applied. Figure 1 is a schematic diagram of the copier 500. The copier 500 is equipped with an image reading unit 12 above the printer unit 100, which is the main body of the image forming apparatus, and a paper feeding unit 7 below the printer unit 100. The image reading unit 12 is equipped with a document reading unit 4 and a document transport unit 3. The document transport unit 3 transports the document to the document reading unit 4, and the document reading unit 4 reads the image information of the transported document. The paper feeding unit 7 is equipped with a paper feed cassette 26 that houses the transfer paper P, which is the recording medium, and a paper feed roller 27 that feeds the transfer paper P in the paper feed cassette 26 toward the printer unit 100. The dashed line in Figure 1 shows the transport path of the transfer paper P within the copier 500.

[0009] The upper part of the printer unit 100 is an output tray 32 on which transfer paper P with the output image formed on it is stacked. The printer unit 100 includes four image-forming units 6 (Y, M, C, K) as image-forming units that form toner images of each color (yellow, magenta, cyan, black), and an intermediate transfer unit 10. The printer unit 100 also includes a writing unit 15, such as an exposure device, that writes an electrostatic latent image onto the surface of each drum-shaped photoreceptor 1 (Y, M, C, K), which serves as an image carrier on which the toner images of each color of each image-forming unit 6 (Y, M, C, K) are formed. Each image-forming unit 6 (Y, M, C, K) includes a developing device 5 (Y, M, C, K) that develops the electrostatic latent image on the surface of each photoreceptor 1 (Y, M, C, K).

[0010] The intermediate transfer unit 10 includes an intermediate transfer belt 8 and primary transfer bias rollers 9 (Y, M, C, K). The intermediate transfer belt 8 is an intermediate transfer body on which the toner images of each color formed on the surface of each photoreceptor 1 (Y, M, C, K) are superimposed and transferred, forming a color toner image on the surface. The primary transfer bias rollers 9 (Y, M, C, K) are primary transfer means that transfer the toner images formed on the surface of each photoreceptor 1 (Y, M, C, K) to the intermediate transfer belt 8.

[0011] The printer unit 100 includes a secondary transfer bias roller 19 for transferring the color toner image on the intermediate transfer belt 8 onto the transfer paper P. It also includes a pair of registration rollers 28 for adjusting the timing of transporting the transfer paper P, fed by the paper feed roller 27, to the secondary transfer nip where the intermediate transfer belt 8 and the secondary transfer bias roller 19 face each other. Furthermore, the printer unit 100 includes a fixing device 20 above the secondary transfer nip for fixing the unfixed toner image on the transfer paper P. Below the output tray 32 in the printer unit 100 and above the intermediate transfer unit 10, toner bottles 11 (Y, M, C, K) for each color are arranged. Each toner bottle 11 (Y, M, C, K) contains the toner for each color (yellow, magenta, cyan, black) that is supplied to each developing unit 5 (Y, M, C, K).

[0012] FIG. 2 is an enlarged explanatory view of one of the four image forming units 6 (Y, M, C, K) to which the present invention is applicable. Since the four image forming units 6 (Y, M, C, K) have substantially the same configuration and operation except that the toner colors used in the image forming process are different, in the following description, the reference signs Y, M, C, K indicating the corresponding colors will be appropriately omitted for explanation. As shown in FIG. 2, the image forming unit 6 serves as a process cartridge that integrally supports the photosensitive member 1 and the developing device 5, and this process cartridge is detachable from the main body of the copying machine 500. Further, the image forming unit 6 includes, in addition to the developing device 5 around the photosensitive member 1, a photosensitive cleaning device 2, a lubricant supply device 13, a charging device 14, and the like. In the image forming unit 6 of the present embodiment, the photosensitive cleaning device 2 is configured to be cleaned by a cleaning blade 2a, and the charging device 14 is configured to be charged by a charging roller 14a.

[0013] The developing device 5 has a first agent storage chamber 5a in which a first transport screw 152 as a developer transport means is disposed. It also has a toner concentration sensor 155 composed of a magnetic permeability sensor as a toner concentration detection means, a second transport screw 153 as a developer transport means, a developing roller 151 as a developer carrier, and the like. Furthermore, it also has a second agent storage chamber 5b in which a doctor blade 154 as a developer regulating member is disposed.

[0014] The toner concentration sensor 155 detects the toner concentration of the developer passing through a predetermined detection location located on the downstream side in the developer circulation direction from a location (hereinafter referred to as the "supply position") facing the toner supply port 5c in the first agent storage chamber 5a.

[0015] In the two agent storage chambers forming the circulation path, a developer composed of a magnetic carrier and a negatively charged toner is stored. The first transport screw 152 is rotationally driven by a driving means to transport the developer in the first agent storage chamber 5a to the front side in the direction perpendicular to the plane of FIG. 2. Then, the developer transported to the end of the first agent storage chamber 5a by the first transport screw 152 enters the second agent storage chamber through the communication port.

[0016] The second conveying screw 153 in the second agent storage chamber 5b is rotationally driven by driving means to convey the developer toward the back side in the direction perpendicular to the plane of FIG. 2. Above the second conveying screw 153, a developing roller 151 is disposed in a posture parallel to the second conveying screw 153. This developing roller 151 has a configuration in which a magnet roller fixed inside a developing sleeve made of a non-magnetic sleeve that is rotationally driven in the counterclockwise direction (direction of arrow B in the figure) in FIG. 2 is included.

[0017] A part of the developer conveyed by the second conveying screw 153 is sucked up to the surface of the developing sleeve by the magnetic force generated by the magnet roller. Then, after the layer thickness is regulated by a doctor blade 154 disposed so as to maintain a predetermined gap from the surface of the developing sleeve, it is conveyed to the developing area facing the photoreceptor 1, and toner is attached to the electrostatic latent image on the photoreceptor 1. By this attachment, a toner image is formed on the photoreceptor 1. The developer that has consumed toner by development is returned to the second conveying screw 153 as the developing sleeve rotates. Then, the developer conveyed to the end of the second agent storage chamber 5b by the second conveying screw 153 returns into the first agent storage chamber 5a through a communication port provided in the partition wall that partitions the two agent storage chambers. In this way, the developer is circulated and conveyed within the developing device.

[0018] The detection result of the toner concentration of the developer by the toner concentration sensor 155 is sent as an electrical signal to a control unit 60 (see FIG. 6) described later. The control unit 60 converts the output voltage from the toner concentration sensor 155 into the toner concentration of the developer. The control unit 60 compares the output voltage from the toner concentration sensor 155 with a target voltage value Vtref that is the target value of the output voltage stored in the storage 51 (see FIG. 6). Then, the toner supply device 41 is driven so as to supply an amount of toner corresponding to the comparison result from the toner supply port 5c, and an appropriate amount of toner is supplied from the toner bottle 11 to the developer in the first agent storage chamber 5a (toner supply control). For this reason, the toner concentration of the developer in the first agent storage chamber 5a is maintained within a predetermined range near the target toner concentration.

[0019] The following describes the operation of the copier 500 of this embodiment during normal color image formation. First, with the original document set on the document tray of the document transport unit 3, when the start button is pressed, the original document is transported from the document tray by the transport rollers of the document transport unit 3 and placed on the contact glass of the document reading unit 4. Then, the image information of the original document placed on the contact glass is optically read by the document reading unit 4.

[0020] In detail, the color image information of the original document is read by a color sensor for each of the RGB (red, green, blue) color separations, and then converted into an electrical image signal. Furthermore, the image processing unit performs color conversion, color correction, spatial frequency correction, and other processing based on the RGB color separation image signal to obtain yellow, magenta, cyan, and black color image information.

[0021] Then, image information for each color—yellow, magenta, cyan, and black—is transmitted to the writing unit 15. From the writing unit 15, laser light L based on the image information for each color is emitted, directed towards the corresponding photoreceptor 1 (Y, M, C, K).

[0022] Meanwhile, the four photoreceptors 1 (Y, M, C, K) are each rotating in a clockwise direction in Figures 1 and 2 (in the direction of arrow A in Figure 2). First, the surfaces of the photoreceptors 1 (Y, M, C, K) are uniformly charged at the point opposite the charging roller 14a of the charging device 14 (charging process). Thus, the surface of the photoreceptors 1 (Y, M, C, K) becomes charged. Subsequently, the charged surface of the photoreceptors 1 (Y, M, C, K) reaches the irradiation position of the laser beam L. In the writing section, laser beams L corresponding to the image signal are emitted from the four light sources, corresponding to each color. Each laser beam L passes through a separate optical path for the yellow, magenta, cyan, and black color components and irradiates the surface of each photoreceptor 1 (Y, M, C, K), forming an electrostatic latent image of each color (exposure process).

[0023] Subsequently, the surfaces of the photoreceptor 1 (Y, M, C, K), on which electrostatic latent images of each color have been formed, reach a position opposite the developing device 5. Then, the toner of each color is supplied from the developer on the developing roller 151 of the developing device 5 (Y, M, C, K), which contains the developer consisting of each color toner and carrier, onto the surface of the photoreceptor 1 (Y, M, C, K), and the latent images on the photoreceptor 1 (Y, M, C, K) are developed (developing process). The direction of transport of the developer by the developing roller 151 is counterclockwise, as indicated by arrow B.

[0024] After passing through the section facing the developing device 5, the surface of each photoreceptor 1 (Y, M, C, K) reaches the section facing the intermediate transfer belt 8. A primary transfer bias roller 9 (Y, M, C, K) is installed at each section so as to contact the inner surface of the intermediate transfer belt 8. The photoreceptor 1 (Y, M, C, K) and the primary transfer bias roller 9 (Y, M, C, K) face each other across the intermediate transfer belt 8, forming a primary transfer nip. At this primary transfer nip, the toner images of each color formed on each photoreceptor 1 (Y, M, C, K) are sequentially transferred onto the intermediate transfer belt 8 (primary transfer process).

[0025] After passing through the primary transfer nip, the surface of the photoreceptor 1 reaches a position opposite the photoreceptor cleaning device 2. At this position opposite the photoreceptor cleaning device 2, any untransferred toner remaining on the photoreceptor 1 is scraped off and collected by the cleaning blade 2a (photoreceptor cleaning process). The surface of the photoreceptor 1 that has passed through the section opposite the photoreceptor cleaning device 2 passes through the static discharge section to remove residual charge, completing the series of imaging processes on the photoreceptor 1 and preparing for the next imaging operation.

[0026] Meanwhile, the toner images of each color on the four photoreceptors 1 (Y, M, C, K) are superimposed and transferred, and the intermediate transfer belt 8, which carries the color toner images, moves counterclockwise across the surface in Figure 1 to reach the secondary transfer nip, which is the position opposite the secondary transfer bias roller 19. Also, the transfer paper P, which is fed from the paper feed cassette 26 containing the transfer paper P by the paper feed roller 27, passes through the transport guide and is led to the register roller pair 28, where it abuts and stops. The transfer paper P that has abutted the register roller pair 28 is transported toward the secondary transfer nip in time with the color toner images formed on the intermediate transfer belt 8 moving toward the secondary transfer nip. Then, at the secondary transfer nip, the color toner images carried on the intermediate transfer belt 8 are transferred onto the transfer paper P (secondary transfer process).

[0027] The surface of the intermediate transfer belt 8, having passed through the secondary transfer nip, reaches the section facing the intermediate transfer belt cleaning device 30. At this section, the remaining transfer toner adhering to the intermediate transfer belt 8 is collected by the cleaning blade 31 and brought to the intermediate transfer belt cleaning device 30, thus completing the series of transfer processes on the intermediate transfer belt 8.

[0028] Untransferred toner scraped off the surface of the photoreceptor 1 by the cleaning blade 2a is collected in the waste toner container via the toner recovery transport path. In addition, untransferred toner scraped off the surface of the intermediate transfer belt 8 by the intermediate transfer belt cleaning device 30, as well as toner for the pattern image used for process control, are also collected in the waste toner container via the toner recovery transport path.

[0029] The transfer paper P, onto which the color toner image has been transferred via the secondary transfer nip, is guided to the fuser unit 20. In the fuser unit 20, the color image is fixed onto the transfer paper P by heat and pressure at the fuser nip formed by the fuser roller and pressure roller. After passing through the fuser unit 20, the transfer paper P is discharged as an output image outside the printer unit 100 by the output roller pair 25 and stacked on the output tray 32, completing the image formation process.

[0030] Above the intermediate transfer unit 10, four toner bottles 11 (Y, M, C, K), which are toner containers that individually house Y toner, C toner, M toner, and K toner, are arranged.

[0031] In this copier 500, process control is implemented at predetermined timings to stabilize image quality in response to environmental fluctuations and over time. Figure 3 is a schematic diagram illustrating the gradation pattern on the intermediate transfer belt.

[0032] The gradation pattern consists of multiple toner patches with different image densities, and these gradation patterns are formed at positions on the intermediate transfer belt 8 opposite the optical sensor unit 40 (the center in the width direction and both ends). In the example shown in Figure 3, gradation patterns of black, cyan, magenta, and yellow are formed from top to bottom.

[0033] The optical sensor unit 40 has multiple optical sensors 40R, 40C, and 40F, which serve as adhesion amount detection means, arranged at predetermined intervals in the belt width direction of the intermediate transfer belt 8. Each optical sensor outputs a signal corresponding to the light reflectance of the intermediate transfer belt 8 and the gradation patterns PK, PC, PM, and PY on the intermediate transfer belt 8, and detects the amount of toner adhered. The copier 500 adjusts the image formation conditions, such as the development bias Vb, based on the detected amount of toner adhered.

[0034] The optical sensors 40R and 40F, positioned opposite the widthwise end region of the intermediate transfer belt 8, are located outside the paper feeding region. Therefore, as shown in Figure 4, during toner image formation on the transfer paper, an image adjustment pattern is formed outside the paper feeding region, and the amount of toner deposited on this image adjustment pattern is detected by the optical sensors 40R and 40F. Based on the amount of toner deposited detected by the optical sensors 40R and 40F, the development bias and other factors can be adjusted to control the image density and other settings.

[0035] The toner's base components, as well as silica, titanium dioxide, and other so-called toner additives added to the toner, are transferred from the photoreceptor 1 to the intermediate transfer belt 8. These toner additives transferred to the intermediate transfer belt 8 can adhere to the belt, causing filming on the belt. Furthermore, if there is a lubricant supply device 13 that applies a lubricant to the surface of the photoreceptor 1, various components contained in the lubricant, such as boron nitride and zinc stearate, are also transferred from the photoreceptor 1 to the intermediate transfer belt 8 in addition to the toner additives. The toner additives and lubricant then interact with each other, which can worsen the filming on the intermediate transfer belt 8. In addition, at the secondary transfer nip, paper dust from the transfer paper P is transferred to the intermediate transfer belt 8 and adheres to the belt, causing paper dust filming. In recent years, the challenges of intermediate transfer belt filming have become more significant due to the increased lifespan and speed of image forming machines.

[0036] This type of filming on the intermediate transfer belt 8 occurs when filming substances, such as silica and other toner additives and various components contained in lubricants, adhere to the intermediate transfer belt 8 due to external pressure (mainly contact pressure with the photoreceptor drum). When filming occurs on the intermediate transfer belt 8, if a full solid image or halftone image is output, toner will not adhere to the areas corresponding to the filming, resulting in abnormal images such as white areas or so-called white spots.

[0037] Furthermore, when filming occurs, the glossiness of the belt decreases. Therefore, if filming occurs in the region of the intermediate transfer belt 8 facing the optical sensors 40R, 40C, and 40F, the output signal changes, making it impossible to accurately detect the amount of gradation pattern deposited on the intermediate transfer belt. In addition, unevenness in the filming state can lead to unstable output from the optical sensors, resulting in problems with proper image adjustment.

[0038] Furthermore, filming may reduce the cleaning performance of the cleaning blade 31. In the belt width direction, the positions corresponding to the placement of the optical sensors 40R, 40C, and 40F on the cleaning blade 31 are frequently input with gradation patterns that have a large amount of toner deposited per unit area. Therefore, if filming occurs in the area of ​​the intermediate transfer belt 8 facing the optical sensors 40R, 40C, and 40F, the risk of cleaning failure (toner slippage) occurring when a gradation pattern is input to the cleaning blade 31 increases.

[0039] The above-mentioned filming can be scraped off by the toner that remains at the contact points between the cleaning blade 31 and the surface of the intermediate transfer belt 8 (hereinafter referred to as the "cleaning points"), and removed from the surface of the intermediate transfer belt 8. Specifically, the filming on the surface of the intermediate transfer belt is scraped off by the unevenness of the toner surface remaining at the cleaning points and the pressure of the cleaning blade 31 on the toner.

[0040] Therefore, in order to suppress filming of the intermediate transfer belt 8, the copier 500 supplies toner to be used for scraping onto the intermediate transfer belt 8 at a predetermined timing. To this end, it forms a toner pattern (referred to as an input toner pattern) on the photoreceptor 1 that is initially transferred to the intermediate transfer belt 8 but not to the transfer paper P, and is input to the cleaning blade 31. By inputting this input toner pattern to the cleaning blade 31, a sufficient amount of toner is ensured to accumulate in the cleaning area.

[0041] Figure 5 illustrates the formation position of the input toner pattern on the intermediate transfer belt. Figure 5 shows the result of printing three images consecutively using a normal image forming operation. As shown in Figure 5, the formation positions of the input toner pattern are as follows: 1. Position in front of the first transfer paper on the secondary transfer nip. 2. Position outside the width of the transfer paper that is fed through the secondary transfer nip. 3. Position of the non-image-forming region at the trailing end of the transfer paper that is passed through the secondary transfer nip. 4. Position between pages 5. Position of the final sheet after it has passed through the secondary transfer nip. These are some examples.

[0042] Regarding point 2 above, this configuration can be adopted in which the width of the intermediate transfer belt is wider than the axial length of the secondary transfer roller, and the secondary transfer roller does not contact the intermediate transfer belt 8 at the position described in point 2. This is because, in the case where the secondary transfer roller 18 contacts the intermediate transfer belt 8 at the position described in point 2, the input toner pattern formed at the position described in point 2 is transferred to the secondary transfer roller 18. Furthermore, since only the end of the intermediate transfer belt in the width direction can be removed at the position described in point 2, it is necessary to combine this with the long, strip-shaped input toner patterns in the width direction of the intermediate transfer belt described in points 1, 3 to 5 above.

[0043] Regarding item 3 above, the position may also be the non-image-forming region at the leading edge of the transfer paper that is fed through the secondary transfer nip. Regarding items 1, 3 to 5 above, when the input toner pattern on the intermediate transfer belt passes through the secondary transfer nip, a positive polarity bias is applied to the opposing roller 18A. By applying a positive polarity bias to the opposing roller 18A, the input toner pattern is electrostatically attracted to the intermediate transfer belt 8, preventing the input toner pattern from being transferred to the secondary transfer roller 18 or the transfer paper P.

[0044] Figure 6 shows an example of a flowchart for forming the input toner pattern described above. The control unit 300 (see Figure 14), which performs various controls in the copier 500, starts measuring the travel distance of the intermediate transfer belt 8 after receiving a print command and starting to drive the intermediate transfer belt 8 (S1). When the intermediate transfer belt 8 stops driving, it calculates the required toner input amount to the cleaning blade 31 based on the filming condition on the surface of the intermediate transfer belt 8, based on the measured travel distance of the intermediate transfer belt 8. Specifically, it calculates the required toner input amount by multiplying the travel distance of the intermediate transfer belt 8 by a coefficient. Then, it calculates the cumulative value of the required toner input amount by adding the calculated required toner input amounts (S2). Next, the control unit determines whether the cumulative value of the required toner input amount exceeds a threshold (S3). If the cumulative value does not exceed the threshold (No in S3), the flow in Figure 6 ends. On the other hand, if the cumulative value exceeds the threshold (Yes in S3), for example, an input toner pattern is formed during the cleaning operation, as will be described later. Then, the amount of toner in the formed input toner pattern (the amount of toner input to the cleaning blade) is subtracted from the above cumulative value (S4). This completes the flow shown in Figure 6.

[0045] In systems that use an optical sensor to detect the presence or absence of filming and form the input toner pattern, even if filming occurs outside the detection range of the optical sensor, the filming outside the area of ​​the intermediate transfer belt opposite the optical sensor will not be removed until filming occurs in the area of ​​the intermediate transfer belt opposite the optical sensor. As a result, there is a risk that the occurrence of abnormal images such as white spots due to filming cannot be adequately suppressed.

[0046] In contrast, in this embodiment, the input toner pattern is formed based on the travel distance of the intermediate transfer belt 8. As a result, even if filming does not occur in the region of the intermediate transfer belt 8 facing the optical sensor, if there is a possibility of filming occurring in other regions, the input toner pattern is formed. Therefore, compared to systems that form the input toner pattern based on the detection results of the optical sensor, filming on the intermediate transfer belt 8 can be removed more effectively.

[0047] The above coefficient may be a fixed value, or for example, the coefficient may be changed between a color image mode and a monochrome image mode. This is because the filming may deteriorate more in the color image mode than in the monochrome image mode. In the color image mode, the fixing set temperature is higher and the number of operating motors increases, so the temperature inside the machine tends to rise. When the temperature inside the machine rises, the amount of stick slip of the cleaning blade 31 increases, and there is a risk that filming will deteriorate. Also, when there is a lubricant supply device 13 for applying a lubricant to the surface of the photoreceptor 1, in the color image mode, the amount of lubricant, which is a component of the filming substance adhering to the intermediate transfer belt 8, increases compared to the monochrome mode. Therefore, there is a risk that filming will deteriorate more in the color image mode than in the monochrome image mode.

[0048] Therefore, for example, the coefficient B in the color image mode is set to a value higher than the coefficient A in the monochrome image mode (A < B). Then, when forming an image (when driving the intermediate transfer belt), it is determined whether it is the monochrome image mode or the color image mode. In the monochrome image mode, the required toner input amount is calculated using the coefficient A, and in the color image mode, the required toner input amount is calculated using the coefficient B.

[0049] For example, when the color image mode is frequent, the risk of filming deterioration is higher than in the monochrome image mode as described above. However, when the color image mode is frequent, the integrated value of the required toner input amount exceeds the threshold value with a short running distance of the intermediate transfer belt 8, so the input toner pattern is formed at an early timing. On the other hand, when the monochrome image mode is frequent, filming is less likely to deteriorate compared to the color image mode. Therefore, when the monochrome image mode is frequent, the running distance at which the integrated value of the required toner input amount exceeds the threshold value becomes longer, and the input toner pattern is formed at a late timing.

[0050] In this way, by forming the input toner pattern based on the image mode, the input toner pattern can be formed at the appropriate timing, effectively suppressing wasted toner consumption and deterioration of filming performance.

[0051] As mentioned above, it is preferable that a sufficient amount of toner remains in the cleaning area to effectively remove the filming on the surface of the intermediate transfer belt 8. However, if the amount of toner in the input toner pattern is increased and a large amount of toner is input to the cleaning area at once, toner may slip through, potentially resulting in poor cleaning.

[0052] This copier has multiple image forming modes, such as standard speed, medium speed, and low speed, in which the linear speed of the intermediate transfer belt 8 differs from one another. The image forming mode can be switched according to the type of paper, the installation environment of the image forming device, and the customer's usage.

[0053] In the standard speed image forming mode described above, the linear speed of the intermediate transfer belt 8 is increased to improve productivity, but this increased speed tends to worsen filming. As a result, in the standard speed image forming mode, in order to properly remove filming on the intermediate transfer belt 8, a larger amount of toner needs to be input to the cleaning area compared to the medium speed and low speed image forming modes described above.

[0054] However, as mentioned above, if the toner amount in the above input toner pattern is increased and a large amount of toner is input to the cleaning area at once, cleaning failures will occur.

[0055] Therefore, in this embodiment, as shown in Figure 7, multiple input toner patterns KP are formed at short intervals. This ensures that the amount of toner in the input toner patterns KP is set to an amount that does not cause cleaning defects, and that the number of input toner patterns KP ensures that there is enough toner to effectively remove the filming on the intermediate transfer belt.

[0056] As shown in Figure 7(b), each input toner pattern KP is a long, strip-shaped pattern in the main scanning direction, longer than the maximum paper width that the device can transport, and extends in the main scanning direction to the opposing regions of the optical sensors 40R and 40F, which are positioned opposite each other at both ends of the intermediate transfer belt 8. This effectively suppresses filming in the maximum paper width region of the intermediate transfer belt 8 where the toner image transferred to the transfer paper P is formed, and effectively suppresses the occurrence of abnormal images such as white spots. Furthermore, the input toner pattern KP extends to the opposing regions of the optical sensors 40R and 40F, which are positioned opposite each other at both ends of the intermediate transfer belt 8. Therefore, filming in the portions of the intermediate transfer belt 8 opposite the optical sensors 40R and 40F can be effectively suppressed, and the amount of toner deposited can be detected effectively.

[0057] The above interval Sp is set so that the next input toner pattern is input before the toner forming the preceding input toner pattern is completely removed from the cleaning area. Furthermore, the above interval Sp is set so that when the next input toner pattern KP is input to the cleaning area, the amount of toner remaining in the cleaning area is less than or equal to the amount of toner that would cause a cleaning failure. This suppresses cleaning failures and effectively suppresses filming.

[0058] Furthermore, as shown in Figure 8, it is preferable to form the three input toner patterns with toners of different colors. This helps to suppress the uneven distribution of toner consumption to a particular color.

[0059] Furthermore, in Figure 8, the downstream input toner pattern of the intermediate transfer belt 8 is C color, the central input toner pattern is M color, and the upstream input toner pattern is Y color, following the arrangement of the imaging unit 6 shown in Figure 1. By making the order of the input toner pattern colors follow the arrangement of the imaging unit 6 in this way, the imaging time for imaging the three input toner patterns can be shortened. An example of the dimensions of each part in the sub-scanning direction is as follows: the C color input toner pattern is 70 mm, the M color input toner pattern is 60 mm, the Y color input toner pattern is 70 mm, and both SPs are 80 mm.

[0060] Alternatively, the three input toner patterns may be formed on the intermediate transfer belt 8 in the order of K, C, and M colors. With this configuration, for example, the imaging time for forming the three input toner patterns can be shortened compared to the case where the C color is skipped, such as when the colors are arranged in the order of K, M, and Y colors. The imaging time is the time from when one of the three imaging units starts the series of imaging processes described above until the last of the three imaging units finishes the series of imaging processes described above.

[0061] As shown in Figures 7 and 8, by forming multiple input toner patterns KP at short intervals, cleaning defects can be suppressed and filming can be removed effectively in the standard-speed image formation mode, where filming tends to deteriorate. However, in the medium-speed and low-speed image formation modes, the linear speed of the intermediate transfer belt 8 is slower than in the standard-speed image formation mode, resulting in a lower filming level compared to the standard-speed mode. Therefore, in the medium-speed and low-speed image formation modes, if multiple input toner patterns KP are formed as shown in Figures 7 and 8, the amount of toner input to the cleaning area becomes excessive relative to the filming state, unnecessarily increasing toner consumption. Thus, it is preferable to use fewer input toner patterns KP in the medium-speed and low-speed image formation modes than in the standard-speed image formation mode.

[0062] Figure 9 is a flowchart illustrating the formation of the input toner pattern KP in this embodiment. As explained using Figure 5, when the cumulative value of the required toner input exceeds the threshold and it is time to form the input toner pattern, the control unit 300 checks whether the set linear speed of the intermediate transfer belt 8 is the standard speed (S11). If the image formation mode is the standard speed image formation mode and the linear speed of the intermediate transfer belt 8 is set to the standard speed (high speed) (Yes in S11), multiple input toner patterns KP are formed at short intervals, as shown in Figures 7 and 8 (S12).

[0063] On the other hand, when the image forming mode is a medium-speed or low-speed image forming mode, and the linear speed of the intermediate transfer belt 8 is set to a medium-speed or low-speed (No. in S11), one input toner pattern KP is formed (S13). Then, the amount of toner in the formed input toner pattern (amount of toner input to the cleaning blade) is subtracted from the above integrated value (S14).

[0064] Thus, in medium-speed or low-speed image forming modes, where the deterioration of filming is milder compared to the standard-speed image forming mode, only one input toner pattern KP is used. Even with only one input toner pattern KP and a small amount of toner input to the cleaning area, filming on the intermediate transfer belt 8 can be removed effectively. This reduces unnecessary toner consumption.

[0065] Furthermore, the threshold value of the cumulative amount of toner input required to determine whether or not to form the input toner pattern, as explained using Figure 6, may be made different for the standard speed image forming mode and the medium speed and low speed image forming modes. Specifically, the threshold value for the standard speed image forming mode may be made lower than the threshold value for the medium speed and low speed image forming modes, and the frequency of input toner pattern formation may be increased in the standard speed image forming mode compared to the medium speed and low speed image forming modes.

[0066] Furthermore, as explained using Figure 6, the required toner input amount is calculated by multiplying the travel distance of the intermediate transfer belt 8 by a coefficient, but this coefficient may be changed for the standard speed image formation mode and the medium speed and low speed image formation modes. Specifically, the value of the coefficient for the standard speed image formation mode is made larger than the value of the coefficient for the medium speed and low speed image formation modes. This makes it possible to increase the formation frequency of the input toner pattern in the standard speed image formation mode compared to the medium speed and low speed image formation modes, and suppress the deterioration of filming in the standard speed image formation mode.

[0067] As described above, the lubricant adhering to the intermediate transfer belt 8 is one factor that worsens the filming on the intermediate transfer belt 8, but it also has the advantage of reducing the coefficient of friction between the surface of the intermediate transfer belt and the cleaning blade 31, thereby suppressing the peeling of the tip of the cleaning blade 31. In particular, since the ends of the cleaning blade 31 facing outside the image forming area on the intermediate transfer belt do not come into contact with residual toner, the transferred lubricant components and the soiled toner reduce the frictional force between the intermediate transfer belt 8 and the cleaning blade 31, preventing the occurrence of blade peeling (hereinafter referred to as blade peeling).

[0068] As shown in Figure 10, when the lubricant supply device 13 contains solid lubricant 13b, the area of ​​the cleaning blade 31 that contacts the paper-feeding area of ​​the intermediate transfer belt 8 receives residual toner, lubricant, and background soiling toner. The area that contacts the non-paper-feeding area receives continuous lubricant and background soiling toner. Therefore, when the lubricant supply device 13 contains solid lubricant 13b, the curling of the tip of the cleaning blade 31 is effectively suppressed, and abnormal wear of the tip of the cleaning blade 31 is suppressed.

[0069] As the image forming operation is repeatedly performed, the solid lubricant 13b is worn down over time, and the size of the solid lubricant 13b decreases. Until now, the image forming unit 6 has been replaced with a new one when it was determined that the lifespan of the image forming unit 6 had ended before the solid lubricant 13b was completely gone, so blade peeling has never occurred.

[0070] With the recent rise in environmental awareness, it has become common practice to use the image-forming unit 6 until the lubricant is completely depleted. In such situations, the image-forming operation continues even after the lubricant around the photoreceptor has run out, and the image-forming operation may continue without any transfer of lubricant to the intermediate transfer belt 8. In this case, the ends of the cleaning blade facing outside the image-forming area on the transfer belt will no longer receive lubricant, making them more prone to peeling.

[0071] The inventors' studies have shown that a photoreceptor surface without lubricant coating exhibits better electrostatic properties and a reduced amount of background toner compared to a photoreceptor surface with lubricant coating. When the lubricant around the photoreceptor is depleted, both the lubricant component, which reduces the frictional force between the cleaning blade 31 and the intermediate transfer belt 8, and the amount of background toner decrease. With no lubricant component intervening between the cleaning blade and the transfer belt, and with a reduced amount of background toner, the frictional force between the cleaning blade and the transfer belt increases in the area outside the paper, making blade peeling more likely.

[0072] Figure 11 illustrates the case when the solid lubricant 13b is depleted. The solid lubricant 13b is biased toward the lubricant supply roller 13a by compression springs 13c at both ends in the longitudinal direction (width direction of the device). However, due to the uneven biasing force between the compression springs 13c, one side in the longitudinal direction (left side in the figure) is depleted faster than the other side (right side in the figure), as shown in Figure 11.

[0073] Therefore, the amount of lubricant adhering to the non-paper-feeding area on the lubricant-depleted side of the intermediate transfer belt 8 decreases. In addition, the amount of background toner supplied from the developing device 5 also decreases. As a result, the frictional force with the intermediate transfer belt 8 increases on the lubricant-depleted side of the cleaning blade 31, and there is a risk that peeling may occur at the tip of the cleaning blade 31 on the lubricant-depleted side.

[0074] If blade peeling occurs, it can lead to serious malfunctions such as the cessation of the image formation operation or damage to the intermediate transfer belt 8. Performing maintenance such as replacing the imaging unit 6 before the lubricant runs out, or replacing only the solid lubricant 13b, as has been done in the past, results in wasted resources and inefficiencies such as downtime for the customer's operations.

[0075] In particular, in recent years, with the growing environmental awareness and from the perspective of waste reduction, the image forming unit 6 may continue to be used without being replaced until the lubricant runs out, or even for a certain period after the lubricant has run out. In such cases, blade peeling occurs, and when blade peeling occurs, in addition to damage to the cleaning blade, intermediate transfer belt rupture often occurs as well, resulting in a long time required to restore the image forming apparatus, which becomes a major problem as it extends the customer's downtime.

[0076] Therefore, in this embodiment, in order to eliminate the waste of resources caused by replacing the image-forming unit 6 prematurely before the lubricant is depleted, and to eliminate inefficiencies due to maintenance, the blade peeling does not occur immediately even if the lubricant is depleted. To this end, after a predetermined number of prints or a predetermined travel distance has been reached during repeated image-forming operations, the amount of toner input to the cleaning blade 31, which cleans the surface of the intermediate transfer belt 8 without transferring it to the recording medium outside the image-forming area, is increased compared to before the operation. This prevents blade peeling even if the solid lubricant 13b mounted on the image-forming unit 6 is depleted.

[0077] Figure 12 is an explanatory diagram of the input toner pattern for increasing the amount of toner input in order to suppress the peeling of the cleaning blade 31 due to lubricant depletion. As shown in Figure 12, in the main scanning direction, outside the image forming area (outside the paper area) of the end of the cleaning blade 31 where lubricant depletion has occurred, more toner image patterns are input than before the set value was reached, preventing peeling. As a result, on the lubricant depleted side of the cleaning blade 31, the toner held back by the cleaning blade 31 improves the slippage between it and the intermediate transfer belt 8, thereby suppressing the peeling of the tip of the cleaning blade 31.

[0078] Unless special measures are taken, it is unclear whether one end or the other end of the solid lubricant 13b in the longitudinal direction will be depleted first. In this case, when the solid lubricant 13b is depleted and reaches the end of its lifespan, an input toner pattern will be formed (primary transfer) in the non-paper-feeding areas on both sides of the intermediate transfer belt 8. For example, if it is possible to determine which end in the longitudinal direction is depleted, or which end will be depleted faster, using the output of optical sensor 40F or optical sensor 40R, the pattern can be formed only on the affected side.

[0079] In this embodiment, when the solid lubricant 13b of one of the multiple image-forming units reaches the end of its lifespan, the control unit 300 changes the input toner pattern from a strip pattern to a combination of a strip pattern and an edge pattern formed at a position outside the width of the transfer paper passed through the secondary transfer nip (as shown in Figure 5, 2). In other words, more toner image patterns are input to the location where the solid lubricant 13b has disappeared than before the solid lubricant 13b disappeared.

[0080] This increases the amount of toner input to the non-paper-feeding area of ​​the cleaning blade 31 (the area that contacts the non-paper-feeding area of ​​the intermediate transfer belt 8) during a predetermined period. As a result, the shortage of background soiling toner can be compensated for, and the curling of the tip of the cleaning blade 31 can be suppressed. Thus, in this embodiment, the control unit 300 functions as a pattern changing means.

[0081] Figure 13 is an explanatory diagram of a modified input toner pattern to suppress peeling of the cleaning blade 31 due to lubricant depletion. It shows the case where the toner image pattern is input not only to the area where the solid lubricant 13b has disappeared, but also to the entire area in the main scanning direction. Similar to Figure 12, the frictional force between the cleaning blade 31 and the intermediate transfer belt 8 is reduced to compensate for the lubricant that can no longer enter due to the depletion of the solid lubricant 13b and the background dirt toner, thereby preventing blade peeling.

[0082] In this embodiment, the determination of whether or not the solid lubricant 13b has reached the end of its lifespan is made as follows. Here, the end of the lifespan of the solid lubricant 13b means that the amount of solid lubricant 13b has decreased to the extent that there are supply deficiencies A on the intermediate transfer belt 8 where the lubricant is not supplied.

[0083] In this embodiment, when the travel distance of the image carrier, the number of printed pages, or both, which are assumed to be the point at which the lubricant will be depleted, reaches a predetermined set value, it is determined that the solid lubricant 13b has been depleted. The specifics will be described later. Upon determining that the solid lubricant 13b has been depleted, the toner input amount is increased to the amount before the set value was reached. By inputting more toner image patterns to the area where the solid lubricant 13b has been depleted than before the set value was reached, the frictional force between the cleaning blade 31 and the transfer belt is reduced to compensate for the lubricant that is no longer entering due to the depletion of the solid lubricant 13b and the background soiled toner, thereby preventing belt peeling.

[0084] Determining whether the solid lubricant 13b has been depleted is essentially the same whether you judge it by the distance traveled or by the number of printed pages, so we will explain it using the number of printed pages below. Specific examples of setting values ​​for the number of printed pages of the image carrier at which the lubricant is expected to be depleted are as follows. If the set lifespan of the image unit 6 is, for example, 500,000 pages, then no abnormal images caused by the image unit 6 will appear up to 500,000 pages. The lifespan of the image unit 6 is set based on how the customer uses it.

[0085] Here, usage refers to factors such as the number of pages printed in a single print command, the total number of pages printed per day, the temperature and humidity environment in which printing takes place, the ratio of monochrome to color images, and the image area ratio. The lifespan of key parts that make up the image unit 6, such as the photoreceptor, charging roller, cleaning blade 31, solid lubricant 13b, and lubricant application blade, will vary depending on this usage. However, assuming a standard customer usage scenario, the lifespan of the image unit 6 is set at 500,000 pages, and the design ensures that malfunctions caused by each key part do not occur within at least 500,000 pages.

[0086] Therefore, if the lifespan of the image unit 6 is set to 500,000 sheets, the design ensures that, under the expected usage by the customer, no part of the solid lubricant 13b will be completely depleted within 500,000 sheets. Thus, if the lifespan of the image unit 6 is set to 500,000 sheets, setting the number of printed sheets at which the lubricant is judged to be depleted to be the same as the lifespan of the image unit 6 (500,000 sheets) will actually result in increasing the toner input before the solid lubricant 13b is depleted at the 500,000-sheet mark. This prevents the timing of increasing the toner input from occurring after the solid lubricant 13b has been depleted.

[0087] Next, we will explain a method for increasing the toner input amount when the number of printed pages reached is deemed to be the point at which the lubricant has been depleted. In the image forming apparatus of the present invention, a lubricant coating member is provided to supply lubricant to the image forming unit 6 in order to extend the lifespan of the photoreceptor 1. As a result, lubricant components are transferred to and solidify on the downstream intermediate transfer belt 8, resulting in so-called filming, which causes problems such as abnormal images and cleaning failures.

[0088] Originally, to prevent filming of the transfer belt, toner is ejected before the job and after the programmer operation, and a toner image pattern that will not be transferred to the paper is input to the cleaning blade 31 to prevent filming. Therefore, when the number of printed sheets on the image carrier reaches a predetermined set value, the toner input amount is increased compared to before the set value was reached, utilizing the toner input control that was originally performed to prevent filming.

[0089] To prevent filming, one method is to increase the amount of toner input to the cleaning blade 31 at once by increasing the length of the image carrier movement direction of one toner image pattern. Another method is to increase the amount of toner input to the cleaning blade 31 at once by increasing the amount of toner attached to one toner image pattern. Furthermore, for example, before exceeding the set value, toner input was performed after a programmer operation once every 200 printed pages. Another method is to change the frequency of programmer operation to once every 100 pages, thereby increasing the frequency of toner input after programmer operation from once every 200 pages to once every 100 pages.

[0090] Alternatively, once the number of printed pages reaches a predetermined set value, a separate method from the filming prevention control can be used to increase the amount of toner input by inputting toner at a frequency such as every 50 or 100 pages. Furthermore, two or more of the above methods can be combined to increase the amount of toner input.

[0091] Furthermore, when the device speed is increased (the number of prints per unit time increases), the filming of the transfer belt tends to deteriorate, so it is necessary to increase the amount of input toner to prevent filming. However, if a large amount of input toner enters at once, cleaning failures may occur.

[0092] Originally, in order to enhance the filming prevention effect when the device speed is increased, the total amount of toner input to the cleaning blade 31 is increased, and the configuration allows for input of multiple toner image patterns with predetermined intervals, where gaps of no toner image are provided between toner image patterns, so as a toner image pattern that does not cause cleaning failures.

[0093] Therefore, when the number of printed pages of the image carrier reaches a predetermined set value, the amount of toner input can be increased compared to before the set value was reached by utilizing the input control of multiple toner image patterns with predetermined intervals, which was originally done to prevent filming. One method to increase the amount of toner input is to increase the length of each toner image pattern in the direction of movement of the image carrier in the multiple toner image patterns with predetermined intervals that were input to prevent filming.

[0094] One method to increase the amount of toner input is to increase the number of toner image patterns that are spaced at predetermined intervals. Another method is to increase the amount of toner deposited on each individual toner image pattern. Furthermore, for example, if toner input occurred after a programmer operation once every 200 printed pages before exceeding a set value, one method to increase toner input is to change the frequency of programmer operation to once every 100 pages, thus increasing the frequency of toner input after programmer operation from once every 200 pages to once every 100 pages.

[0095] Alternatively, once the number of printed pages reaches a predetermined set value, a method exists to increase the amount of toner input by inputting toner at a frequency such as every 50 or 100 pages, separate from the filming prevention control. Furthermore, a method exists to increase the amount of toner input by combining two or more of the above methods.

[0096] Next, we will describe another embodiment of a method for increasing the toner input amount when the number of printed pages reached is deemed to be the point at which the lubricant has been depleted. The occurrence of peeling of the cleaning blade 31 is closely related to the internal temperature of the machine and the image formation velocity (movement speed of the image carrier). It is known that peeling is more likely to occur when the internal temperature of the image forming apparatus and the temperature near the cleaning blade 31 are high, and less likely to occur when the internal temperature and the temperature near the cleaning blade 31 are low.

[0097] Therefore, after reaching the number of printed pages at which it is determined that the lubricant has been depleted, the amount of toner input increase is changed according to the internal temperature of the machine or the temperature near the cleaning blade 31. When the internal temperature or the temperature near the cleaning blade 31 is low, the risk of peeling is relatively lower compared to when the temperature is high, so the amount of toner input increase is relatively smaller compared to when the temperature is high. By implementing this control, it is possible to prevent unnecessary toner input and prevent an increase in toner consumption.

[0098] Furthermore, it has been found that when the image forming velocity of the image forming apparatus is high (e.g., 300 mm / s), peeling is more likely, and when the image forming velocity is low (256 mm / s), peeling is less likely. When the image forming velocity is low, the risk of peeling is relatively lower compared to when it is high, so the increase in toner input is relatively smaller compared to when the velocity is high. By implementing this control, it is possible to prevent unnecessary toner input and prevent an increase in toner consumption.

[0099] Next, we will explain how the lifespan of an image forming apparatus, in which a black toner-using Bk image forming unit and a color toner-using image forming unit are opposed to each other on a common intermediate transfer belt 8, is determined by using the number of prints of the Bk image forming unit 6K. The apparatus of the present invention is equipped with four color image forming units 6: Bk, C, M, and Y. In the case of monochrome image printing, basically only the Bk image forming unit 6K operates, and in the case of color image printing, all four image forming units 6 (Bk, C, M, and Y) operate.

[0100] During color image printing, four image-forming units 6 are in operation, so the lubricant from four solid lubricants 13b is transferred to the transfer belt. On the other hand, during monochrome image printing, only one Bk image-forming unit 6K is in operation, so the lubricant from one solid lubricant 13b is transferred to the transfer belt. Compared to color image printing, only 1 / 4 of the lubricant is transferred during monochrome image printing.

[0101] From the perspective of transfer belt filming, monochrome image printing is advantageous for filming, but from the perspective of blade curling, monochrome image printing is disadvantageous for curling. If the lubricant in the Bk imaging unit 6K is depleted, only the Bk imaging unit 6K operates during monochrome image printing, so there is no lubricant transfer from the C, M, and Y imaging units 6 to the transfer belt, resulting in no lubricant transfer to the transfer belt at all, which causes blade curling.

[0102] On the other hand, even if the lubricant in the Bk image unit 6K is depleted, if color image printing is in progress, lubricant transfer occurs from the C, M, and Y image units 6 to the transfer belt, so blade peeling does not occur. As a result, there is no transfer of lubricant to the transfer belt at all, and blade peeling is likely to occur when the lubricant in the Bk image unit 6K is depleted during monochrome image printing in Bk mode. Therefore, based on the number of pages printed by the Bk image unit 6K, it is possible to determine that the lubricant has been depleted and, once a predetermined number of pages has been printed, increase the toner input amount to prevent blade peeling.

[0103] This section describes the control mechanism that increases the input toner amount by changing the toner image pattern setting according to the number of prints or travel distance of the photoconductor 1, using block diagrams and flowcharts. Figure 14 is a block diagram relating to the "setting of the toner image pattern" input to the cleaning blade 31, which cleans the surface of the intermediate transfer belt 8 without transferring it to the recording medium. Figure 15 is a flowchart.

[0104] As shown in Figure 14, the control unit 300 includes at least a print count storage unit 301 that stores the number of prints made by the image carrier (photoreceptor 1), a determination unit 302 that determines whether or not the solid lubricant 13b has reached the end of its lifespan, a toner image pattern setting unit 303, and an image controller unit 304. As mentioned above, the travel distance of the image carrier (photoreceptor 1) may be counted instead of the number of prints.

[0105] The print count storage unit 301 counts the number of prints used for each of the K, C, M, and Y color photoreceptors 1 from the time the image-making unit 6 was first used until the present (steps 1 and 2 in Figure 15). Furthermore, the number of prints for the photoreceptor 1 indicates how many prints the solid lubricant 13b has been depleted by the lubricant supply roller 13a, thus serving as an indicator for estimating the remaining amount of solid lubricant 13b.

[0106] The determination unit 302 compares the cumulative number of printed pages from the start of use to the present with a predetermined number of printed pages (threshold) to determine whether the number of printed pages has reached the threshold. If the determination unit 302 determines that the threshold has been reached, the toner image pattern setting unit 303 changes from the toner image pattern setting before reaching the threshold to the toner image pattern setting after reaching the threshold so that the input toner amount after reaching the threshold is greater than before reaching the threshold (if no in step 3 of Figure 15, then step 5).

[0107] Increasing the input toner amount here means increasing the amount of input toner per unit printed page or per unit travel distance. Compared to before the threshold is reached, the setting is changed to increase the input toner amount after the threshold is reached using one of the methods described above.

[0108] The image controller unit 304 controls at least the writing unit 15, the charging device 14, the developing device 5, the toner supply device 41, and the transfer device (primary transfer unit, secondary transfer unit), etc. Under the control of the image controller unit 304, a toner image pattern is formed on the photoreceptor 1 according to the toner image pattern setting determined by the toner image pattern setting unit 303. The toner image pattern is transferred onto the transfer belt in the primary transfer unit, and in the secondary transfer unit, the toner image pattern is not transferred to the transfer paper but reaches the cleaning blade 31 for the transfer belt. This control unit 300 corresponds to the toner input control means.

[0109] The above embodiments can be understood as follows: An image forming apparatus comprising at least a latent image carrier, a lubricant application member for supplying lubricant to the surface of the latent image carrier, an intermediate transfer belt 8, and a cleaning blade 31 for cleaning the surface of the intermediate transfer belt 8, wherein the apparatus performs an operation to appropriately form a toner image pattern on the intermediate transfer belt 8 that is input to the cleaning blade 31 for cleaning the surface of the intermediate transfer belt 8 without transferring it to a recording medium, wherein at least when the travel distance of the latent image carrier reaches a predetermined distance, or when the number of printed sheets of the latent image carrier reaches a predetermined number of printed sheets, or when both the travel distance and the number of printed sheets reach a predetermined distance and / or number of printed sheets, the amount of toner input to the toner image pattern input to the cleaning blade 31 for cleaning the surface of the intermediate transfer belt 8 without transferring it to a recording medium, at least outside the image forming area, is increased compared to before reaching the predetermined distance or number of printed sheets.

[0110] According to this, when the lubricant is depleted, the lubricating components stop reaching the blade, making it more prone to peeling. Therefore, increasing the amount of toner input to the blade and reducing the frictional force between the transfer belt and the cleaning blade 31 can prevent blade peeling.

[0111] Ideally, the image-making unit 6 could be replaced at the exact moment the solid lubricant 13b runs out, by providing a means for detecting the remaining amount of solid lubricant 13b in the image-making unit 6. However, providing such a means would lead to an increase in the size and cost of the device. According to this embodiment, a means for preventing blade peeling is taken separately from unit replacement before the lubricant runs out, without providing a means for detecting the remaining amount of lubricant. Therefore, even if the lubricant runs out, blade peeling can be prevented, independently of providing a means for detecting the remaining amount of lubricant or replacing the unit.

[0112] Although preferred embodiments of the present invention have been described above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the spirit of the present invention as described in the claims, unless otherwise specifically limited in the above description. The effects described in the embodiments of the present invention are merely a list of the most preferred effects arising from the present invention, and the effects according to the present invention are not limited to those described in the embodiments of the present invention.

[0113] The above description is merely an example, and the present invention provides specific effects for each of the following embodiments. In the description of the embodiments, the symbols in parentheses after the component names are examples of corresponding components and are not limited to these examples. (Aspect 1) The system comprises an image carrier (1) on which a toner image of the image to be formed is formed, an intermediate transfer body (8) to which the toner image of the image carrier (1) is transferred, a transfer member that transfers the toner image of the intermediate transfer body (8) to a recording medium, a cleaning member (31) that cleans the surface of the intermediate transfer body (8) after the toner image has been transferred to the recording medium, a lubricant supply means (13) that supplies lubricant to intermediate transfer body opposing members (8, 19) that face the intermediate transfer body (8) such as the image carrier (1), and a means that forms a toner image on the surface of the image carrier (1) where no image has been formed, transfers the toner image to the intermediate transfer body (8), and the cleaning member In an image forming apparatus (500) comprising a toner input control means (300) that inputs toner to the contact area of ​​(31), a determination means (302) is provided to determine whether or not a non-supply area (A) occurs on the intermediate transfer body (8) due to a decrease in lubricant in the lubricant supply means (13) and lubricant is not supplied via the intermediate transfer body opposing members (8, 19), and the toner input control means (300) is characterized in that when the determination means (302) determines that a non-supply area (A) has occurred, the amount of toner that enters the contact area of ​​the cleaning member (31) is increased compared to before the determination that a non-supply area (A) has occurred.

[0114] (Aspect 2) In the image forming apparatus (500) described in Embodiment 1, the determination means (302) is characterized in that it determines whether or not a non-supply location (A) has occurred based on the cumulative amount of surface movement of the intermediate transfer body opposing members (8, 19) since the start of lubricant use.

[0115] (Aspect 3) In the image forming apparatus (500) described in Embodiment 1, the intermediate transfer body opposing members (8, 19) are image carriers (1), and the determination means (302) determines that a non-supply location (A) has occurred when the cumulative number of image forming operations since the start of lubricant use reaches a predetermined number, or when the cumulative surface travel distance reaches a predetermined distance.

[0116] (Aspect 4) In the image forming apparatus (500) described in any one of embodiments 1 to 4, the non-supply location (A) is a partial location on the surface of the intermediate transfer body (8) in a direction perpendicular to the surface movement direction, and the toner input control means (300) is characterized in that it increases the amount of toner to at least a predetermined portion of the location where the non-supply location (A) is assumed to be, in a direction perpendicular to the surface movement direction of the intermediate transfer body (8).

[0117] (Appendix 5) In the image forming apparatus (500) described in Embodiment 4, a predetermined portion is located outside the region facing the transfer body in a direction perpendicular to the surface movement direction of the intermediate transfer body, and is a region to which lubricant from the lubricant supply means (13) is applied.

[0118] (Aspect 6) In the image forming apparatus (500) described in any one of embodiments 1 to 5, the toner input means increases or decreases the amount of toner according to predetermined conditions even before the determination means (302) determines that a non-supply location (A) has occurred, and when the determination means (302) determines that a non-supply location (A) has occurred, it increases the amount of toner to the amount according to the predetermined conditions before the determination means (302) determined that a non-supply location (A) has occurred.

[0119] (Aspect 7) In the image forming apparatus (500) described in Embodiment 6, the predetermined conditions are characterized in that they are conditions related to at least one of the temperature inside the image forming apparatus (500) and the linear velocity of the image forming apparatus (500). According to this, blade peeling is more likely to occur when the internal temperature of the machine or the temperature near the cleaning component (31) is high, and less likely to occur when the internal temperature of the machine or the temperature near the cleaning component (31) is low. Therefore, when the internal temperature of the machine or the temperature near the cleaning component (31) is high and peeling is likely to occur, the amount of toner input can be increased, and when the internal temperature of the machine or the temperature near the cleaning component (31) is low, the amount of toner input can be increased less than when the temperature is high, thereby preventing unnecessary toner input and suppressing toner consumption.

[0120] Furthermore, since the faster the line speed during image formation, the more likely the image is to peel off, increasing the amount of toner input when the line speed is high (e.g., 300 mm / s) and decreasing the amount of toner input when the line speed is slow (256 mm / s) compared to when the line speed is high prevents unnecessary toner input and reduces toner consumption.

[0121] (Pattern 8) In the image forming apparatus (500) described in any one of embodiments 1 to 7, an image carrier (1) is provided with a black toner image carrier (1) on which a black toner image is formed and at least one color toner image carrier (1) on which a color toner image is formed, facing a common intermediate transfer body (8), and each of the black toner image carrier (1) and at least one color toner image carrier (1) is provided with a lubricant supply means (13), and the determination means (302) determines the location (A) where lubricant is not supplied from the lubricant supply means (13) of the black toner image carrier (1). According to this method, by determining lubricant depletion based on the travel distance of the latent image carrier (Bk), which is most prone to lubricant depletion, or the number of printed sheets, peeling can be reliably prevented.

[0122] (Aspect 9) In the image forming apparatus (500) described in any one of embodiments 1 to 8, when forming an input toner image, multiple images are formed at intervals in the direction of movement of the intermediate transfer body (8). According to this, before the lubricant is depleted, it is possible to achieve both film prevention and cleaning ability, and after the lubricant is depleted, it is possible to prevent filming, cleanability, and blade peeling.

[0123] (Aspect 10) In the image forming apparatus (500) described in any one of embodiments 1 to 9, the increase in toner amount is characterized by increasing the length of the toner image carrier (1) in the direction of movement, increasing the number of toner images in the direction of movement of the toner image carrier (1), increasing the frequency of toner image formation (the travel distance of the latent image carrier, or the frequency of toner image input pattern formation relative to the number of printed sheets), and increasing the amount of toner attached per unit area of ​​the toner image. This makes it possible to prevent peeling, which can occur when lubricant depletion reduces the amount of lubricant components supplied to the blade, by increasing the amount of toner input to the blade. [Explanation of Symbols]

[0124] 1: Photoreceptor 2: Photoconductor cleaning device 2a: Cleaning blade 3: Manuscript transport section 4: Manuscript reading unit 5: Developing equipment 5a: First agent containment room 5b: Second agent containment room 5c: Toner refill port 6: Image creation unit 6K: Black Image Unit 7:Paper feed section 8: Intermediate transfer belt 9: Primary transfer bias roller 10: Intermediate transfer unit 11: Toner bottle 12: Image reading unit 13: Lubricant supply device 13a: Lubricant supply roller 13b: Solid lubricant 13c: Compression spring 14: Charging device 14a: Electrostatic roller 15: Writing section 18: Secondary transfer roller 18A: Opposing rollers 19: Secondary transfer bias roller 20: Fixing device 25: Paper output roller pair 26: Paper feed cassette 27: Paper feed roller 28: Resistola vs. 30: Intermediate transfer belt cleaning device 31: Cleaning blade 32: Paper output tray 40: Optical sensor unit 40C: Optical sensor 40F: Optical sensor 40R: Optical sensor 41: Toner replenishment device 51: Storage 60: Control Unit 100: Printer section 151: Developing Roller 152: First conveyor screw 153: Second transport screw 154: Doctor Blade 155: Toner density sensor 300: Control Unit 301: Print count storage unit 302: Judgment section 303: Toner image pattern setting unit 304: Image creation controller unit 500: Photocopier A: Locations where supplies are unavailable KP: Input Toner Pattern L: Laser light P: Transfer paper PK: Tone Pattern [Prior art documents] [Patent Documents]

[0125] [Patent Document 1] Patent No. 4524164

Claims

1. An image forming apparatus comprising: an image carrier on which a toner image of an image to be formed is formed; an intermediate transfer body onto which the toner image of the image carrier is transferred; a transfer member for transferring the toner image of the intermediate transfer body to a recording medium; a cleaning member for cleaning the surface of the intermediate transfer body after the toner image has been transferred to the recording medium; a lubricant supply means for supplying lubricant to an intermediate transfer body opposing member facing the intermediate transfer body, such as the image carrier; and a toner input control means for forming a toner image on a surface portion of the image carrier where the image has not been formed, transferring the toner image to the intermediate transfer body, and inputting it to the contact portion of the cleaning member, wherein the image forming apparatus is provided with a determination means for determining whether or not a non-supply area has occurred on the intermediate transfer body due to a decrease in lubricant in the lubricant supply means, and when the determination means determines that a non-supply area has occurred, the toner input control means increases the amount of toner to enter the contact portion of the cleaning member compared to before the determination that a non-supply area has occurred.

2. The image forming apparatus according to claim 1, wherein the determination means determines whether or not the non-supply location has occurred based on the cumulative amount of movement of the surface of the intermediate transfer body opposing member since the start of lubricant use.

3. An image forming apparatus according to claim 1, wherein the intermediate transfer body opposing member is the image carrier, and the determination means determines that the non-supply location has occurred in at least one of the following cases: when the cumulative number of image forming operations since the start of lubricant use reaches a predetermined number, or when the cumulative surface travel distance reaches a predetermined distance.

4. The image forming apparatus according to claim 1, wherein the non-supply location is a partial location on the surface in a direction perpendicular to the surface movement direction of the intermediate transfer body, and the toner input control means increases the amount of toner to at least a predetermined portion of the location where the non-supply location is assumed, in a direction perpendicular to the surface movement direction of the intermediate transfer body.

5. The image forming apparatus according to claim 4, wherein a predetermined portion is outside the region where the recording medium faces in a direction perpendicular to the surface movement direction of the intermediate transfer body, and is a region to which lubricant from the lubricant supply means is applied.

6. The image forming apparatus according to claim 1, wherein the toner input control means increases or decreases the amount of toner according to predetermined conditions even before the determination means determines that the non-supply location has occurred, and when the determination means determines that the non-supply location has occurred, it increases the amount of toner to the amount according to the predetermined conditions before the determination that the non-supply location has occurred.

7. An image forming apparatus according to claim 6, characterized in that the predetermined conditions are conditions related to at least one of the temperature inside the image forming apparatus and the linear velocity of the image forming apparatus.

8. The image forming apparatus according to claim 1, wherein the image carrier comprises a black toner image carrier on which a black toner image is formed and at least one color toner image carrier on which a color toner image is formed, both arranged opposite a common intermediate transfer body, and the lubricant supply means is provided for each of the black toner image carrier and at least one color toner image carrier, and the determination means determines the location of the non-supply of lubricant from the lubricant supply means for the black toner image carrier.

9. An image forming apparatus according to any one of claims 1 to 8, characterized in that when forming the toner image, a plurality of images are formed at intervals in the direction of movement of the intermediate transfer body.

10. An image forming apparatus according to any one of claims 1 to 8, characterized in that the increase in the amount of toner is achieved by at least one of the following: increasing the length of the image carrier of the toner image in the direction of movement; increasing the number of toner images in the direction of movement of the image carrier; increasing the frequency of toner image formation; and increasing the amount of toner deposited per unit area of ​​the toner image.

Images