Image forming apparatus

Abstract

To prevent advance of filming while reducing unnecessary toner consumption in an image forming apparatus using developer including toner particles and lubricant particles.SOLUTION: An image forming apparatus forms, on a recording material P, an image formed on a latent image carrier by a developing device using developer including toner particles and lubricant particles, and the apparatus has control means that executes pattern image forming control of forming a toner pattern TP not formed on the recording material with the toner particles during an image forming operation or in a period before the start or after the completion of the image forming operation. The control means executes the pattern image forming control such that the toner pattern is not formed in a width area corresponding to a part or all within the maximum image width of an image formed during the image forming operation, and is formed in a width area corresponding to the outside of the maximum image width of the image formed during the image forming operation.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, an image forming apparatus that forms an image formed on a latent image carrier on a recording material by a developing device using a developer containing toner particles and lubricant particles is known.

[0003] Patent Document 1 discloses an image forming apparatus that forms a toner image on a photoreceptor (latent image carrier) with a developer containing toner (toner particles) and a lubricating external additive (lubricant particles) charged with a polarity opposite to the charging polarity of the toner. In this image forming apparatus, in order to keep the amount of the lubricating external additive on the photoreceptor within an appropriate range, a strip-shaped patch image (toner pattern) extending over all within the maximum image width and outside the maximum image width is formed in an image area corresponding to between recording materials continuously fed during the image forming operation.

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in a conventional image forming apparatus using a developer containing toner particles and lubricant particles, there is a problem of a large amount of wasted toner consumption.

Means for Solving the Problems

[0005] In order to solve the above-described problems, the present invention is an image forming apparatus that forms an image formed on a latent image carrier on a recording material by a developing device using a developer containing toner particles and lubricant particles, and has control means for executing pattern imaging control for imaging a toner pattern that is not formed on the recording material with the toner particles during the image forming operation or during a period before or after the start or end of the image forming operation, and the control means is configured such that the toner pattern is within the maximum image width formed during the image forming operation AllThe pattern image formation control is performed such that no image is formed in the width region corresponding to the part, but an image is formed in the width region corresponding to the maximum image width formed during the image formation operation, and the control means is characterized in that the pattern image formation control is performed such that the width of the toner pattern is increased as the maximum image width formed during the image formation operation becomes smaller. [Effects of the Invention]

[0006] According to the present invention, in an image forming apparatus using a developer containing toner particles and lubricant particles, it is possible to suppress the deterioration of filming while suppressing unnecessary toner consumption. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of a tandem-type color copier, which is an electrophotographic image forming apparatus according to this embodiment. [Figure 2] This figure illustrates an example of the formation position of the scraping toner pattern on the intermediate transfer belt of the copier. [Figure 3] A diagram illustrating another example of the formation location of the scrape toner pattern on the intermediate transfer belt of the same copier. [Figure 4] A diagram illustrating yet another example of the formation location of the scraping toner pattern on the intermediate transfer belt of the same copier. [Figure 5] A graph showing an example of the relationship between the image area ratio per unit travel distance and the toner consumption (toner ejection amount) due to the scraping toner pattern in the embodiment. [Figure 6] A diagram illustrating yet another example of the formation location of the scraping toner pattern on the intermediate transfer belt of the same copier. [Figure 7] A flowchart illustrating an example of pattern formation control for a scraping toner pattern in an embodiment. [Modes for carrying out the invention]

[0008] One embodiment of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram of a tandem-type color copier (hereinafter simply referred to as "copier") which is an electrophotographic image forming apparatus according to this embodiment. The copier 1 of this embodiment includes a document transport unit 3 for transporting the original document to the document reading unit, a document reading unit 4 for reading the image information of the original document, a paper output tray 5 on which the output image is loaded, and a paper feeding unit 7 for which the paper P, which is the recording material, is stored.

[0009] Furthermore, the copier 1 includes a registration roller 9 (timing roller) for adjusting the transport timing of the paper P, and photoreceptor drums 11Y, 11M, 11C, and 11BK which are latent image carriers on which toner images of each color (yellow, magenta, cyan, and black) are formed. The copier 1 also includes a charging device 12 for uniformly charging the surface of each photoreceptor drum 11Y, 11M, 11C, and 11BK, and a writing unit (exposure unit) 6 which emits laser light based on input image information and writes electrostatic latent images onto each photoreceptor drum 11Y, 11M, 11C, and 11BK. The copier 1 also includes a developing device 13 for developing the electrostatic latent images written on each photoreceptor drum 11Y, 11M, 11C, and 11BK. The copier 1 also includes an intermediate transfer belt 17 which is an intermediate transfer body on which toner images of multiple colors are superimposed. Furthermore, the copier 1 is equipped with a primary transfer bias roller 14 that transfers the toner images formed on each photoreceptor drum 11Y, 11M, 11C, and 11BK onto an intermediate transfer belt 17.

[0010] Furthermore, the copier 1 is equipped with a secondary transfer roller 18 for transferring the color toner image on the intermediate transfer belt 17 onto the paper P. The copier 1 is also equipped with a developer container 28, which serves as a developer reservoir, containing a developer containing toner (toner particles) and lubricant (lubricant particles) of each color (yellow, cyan, magenta, black) for supply to a fuser 20 for fixing the unfixed image on the paper P and a developer 13. The copier 1 is also equipped with a belt cleaning device 30 having a cleaning member for removing toner (untransferred toner) adhering to the surface of the intermediate transfer belt 17. In addition, the copier 1 is equipped with a waste toner collection container in which the untransferred toner removed by the belt cleaning device 30 and the like is collected as waste toner.

[0011] The following describes the operation of the image forming apparatus during normal color image formation. First, the document is transported from the document glass 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 document placed on the contact glass is optically read by the document reading unit 4.

[0012] In detail, the document scanning unit 4 scans the image of the document on the contact glass while illuminating it with light emitted from the illumination lamp, and forms an image on the color sensor via a group of mirrors and lenses with the light reflected from the document. The color image information of the document is read by the 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 processing, color correction processing, spatial frequency correction processing, etc., based on the RGB color separation image signals to obtain yellow, magenta, cyan, and black color image information.

[0013] Image information for each color—yellow, magenta, cyan, and black—is transmitted to the writing unit 6. Then, the writing unit 6 emits laser light L based on the image information for each color, directed towards the surface of the corresponding photosensitive drums 11Y, 11M, 11C, and 11BK.

[0014] Meanwhile, the four photoreceptor drums 11Y, 11M, 11C, and 11BK are each rotating clockwise as shown in Figure 1. First, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK are uniformly charged at the point opposite the charging device 12 (charging process). In this way, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK are charged to a predetermined charging potential. Subsequently, the charged surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK reach the respective laser beam irradiation positions.

[0015] In the writing unit 6, laser light corresponding to the image signal is emitted from four light sources, each corresponding to a different color. Each laser beam passes through a separate optical path for the yellow, magenta, cyan, and black color components (exposure process).

[0016] The laser beam corresponding to the yellow component is shone onto the surface of the first photoreceptor drum 11Y from the left side of the paper. At this time, the laser beam of the yellow component is scanned in the direction of the rotation axis (main scanning direction) of the photoreceptor drum 11Y by a high-speed rotating polygon mirror. In this way, an electrostatic latent image corresponding to the yellow component is formed on the surface of the photoreceptor drum 11Y after it has been charged by the charging device 12.

[0017] Similarly, the laser light corresponding to the magenta component is shone onto the surface of the second photoreceptor drum 11M from the left of the paper, forming an electrostatic latent image corresponding to the magenta component. The laser light corresponding to the cyan component is shone onto the surface of the third photoreceptor drum 11C from the left of the paper, forming an electrostatic latent image of the cyan component. The laser light corresponding to the black component is shone onto the surface of the fourth photoreceptor drum 11BK from the left of the paper, forming an electrostatic latent image of the black component.

[0018] Subsequently, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK, on ​​which electrostatic latent images of each color have been formed, reach a position opposite the developing unit 13. Then, toner of each color is supplied from the developing unit 13 onto the photoreceptor drums 11Y, 11M, 11C, and 11BK, and the latent images on the photoreceptor drums 11Y, 11M, 11C, and 11BK are developed (developing process).

[0019] After the development process, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK reach the opposing portions with the intermediate transfer belt 17, respectively. Here, at each opposing portion, a primary transfer bias roller 14 is installed so as to contact the inner peripheral surface of the intermediate transfer belt 17. And at the position of the primary transfer bias roller 14, the toner images of each color formed on the photoreceptor drums 11Y, 11M, 11C, and 11BK are sequentially superimposed and primarily transferred onto the intermediate transfer belt 17 (primary transfer process).

[0020] After the primary transfer process, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK reach the opposing positions with the cleaning unit 15 having a cleaning member, respectively. And at the cleaning unit 15, the untransferred toner remaining on the photoreceptor drums 11Y, 11M, 11C, and 11BK is removed and recovered by the cleaning member (cleaning process). Note that the untransferred toner removed and recovered by the cleaning unit 15 is conveyed through a conveyance path and conveyed and recovered as waste toner into a waste toner recovery container. Thereafter, the surfaces of the photoreceptor drums 11Y, 11M, 11C, and 11BK pass through a charge removal unit, and a series of image forming processes on the photoreceptor drums 11Y, 11M, 11C, and 11BK are completed.

[0021] On the other hand, the intermediate transfer belt 17 on which the toner images of each color on the photoreceptor drums 11Y, 11M, 11C, and 11BK are superimposed and primarily transferred (carried) travels in the counterclockwise direction in FIG. 1 and reaches the opposing position with the secondary transfer roller 18. The secondary transfer roller 18 contacts the intermediate transfer belt 17 and forms a secondary transfer nip which is a transfer nip. At this secondary transfer nip, the color toner image carried on the intermediate transfer belt 17 is secondarily transferred onto the paper P (secondary transfer process).

[0022] A secondary transfer bias is applied to the opposing roller 18A, which is located opposite the secondary transfer roller 18 via the intermediate transfer belt 17, and the secondary transfer roller 18 is electrically grounded. When secondary transfer of the color toner image on the intermediate transfer belt 17 to the paper P, a negative polarity transfer bias, which is the normal charge polarity of the toner, is applied to the opposing roller 18A, and the negative polarity normal charge toner on the intermediate transfer belt is repulsively transferred to the paper P.

[0023] The surface of the intermediate transfer belt 17 after the secondary transfer process reaches the position of the belt cleaning device 30. The belt cleaning device 30 has a cleaning blade 31, which is a cleaning member. This cleaning blade 31 removes toner (untransferred toner) that has adhered to the intermediate transfer belt 17. The toner removed by the cleaning blade 31 is transported via a transport path to a waste toner collection container as waste toner and collected.

[0024] Here, the paper P that is transported between the intermediate transfer belt 17 and the secondary transfer roller 18 (secondary transfer nip) is transported from the paper feeding unit 7 via the registration roller 9, etc. Specifically, the paper P is fed from the paper feeding unit 7, which stores the paper P, by the paper feeding roller 8, passes through the transport guide, and is then guided to the registration roller 9. Once the paper P reaches the registration roller 9, it is transported toward the secondary transfer nip at the appropriate timing.

[0025] The paper P onto which the full-color image has been transferred in the secondary transfer process is then guided to the fuser 20. In the fuser 20, the color image is fixed onto the paper P by the nip between the fuser roller and the pressure roller. After the fixing process, the paper P is discharged as an output image from the main body of the device by the output roller and stacked on the output tray 5, completing the series of image formation processes.

[0026] In this copier, 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 drum 11 to the intermediate transfer belt 17. These toner additives transferred to the intermediate transfer belt 17 can adhere to the belt, causing filming to occur on the belt. In addition, in this copier, lubricant is supplied to the surface of the photoreceptor drum 11 along with the toner from the developing unit 13. Therefore, in addition to the toner additives, various components contained in the lubricant are also transferred from the photoreceptor drum 11 to the intermediate transfer belt 17. The interaction between the toner additives and the lubricant can worsen the filming on the intermediate transfer belt 17.

[0027] Such filming of the intermediate transfer belt 17 occurs when filming substances, such as silica and other toner additives and various components contained in lubricants, adhere to the intermediate transfer belt 17 due to external pressure on the intermediate transfer belt 17 (mainly contact pressure with the photoreceptor drum). When filming occurs on the intermediate transfer belt 17, when outputting a full solid image or a halftone image, the toner is not properly supported in the areas corresponding to the filming, resulting in abnormal images such as white spots.

[0028] Furthermore, when filming occurs, the glossiness of the surface of the intermediate transfer belt 17 decreases. Therefore, if filming occurs in the belt width region facing the optical sensor 40, such as the toner adhesion amount sensor, which is facing the surface of the intermediate transfer belt 17, the output signal of the optical sensor 40 changes, making it impossible to properly detect the amount of toner adhesion, such as the gradation pattern, on the intermediate transfer belt 17.

[0029] 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 17 (hereinafter referred to as "cleaning points"), and thus removed from the surface of the intermediate transfer belt 17. Specifically, the filming on the intermediate transfer belt 17 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.

[0030] Therefore, in this copier 1, in order to suppress filming of the intermediate transfer belt 17, a scraping toner pattern is formed on the intermediate transfer belt 17 at a predetermined timing. Then, by inputting this scraping toner pattern to the cleaning blade 31, a sufficient amount of toner remains at the cleaning location to achieve the effect of removing filming.

[0031] Figure 2 illustrates an example of the formation position (width region) of the scraping toner pattern TP on the intermediate transfer belt 17. The example shown in Figure 2 illustrates how to form an image on paper with the maximum paper width usable by this copier 1.

[0032] In the copier 1 of this embodiment, a method of supplying lubricant to the photoreceptor drum 11 and the intermediate transfer belt 17 is employed, which involves using a developer containing toner and lubricant. When this supply method is employed, lubricant can be supplied to the photoreceptor drum 11 and the intermediate transfer belt 17 without providing a separate lubricant supply device (for example, a device that applies powdered lubricant attached to a brush to the photoreceptor drum). However, the present invention may also include a separate lubricant supply device as long as this supply method is employed.

[0033] When this supply method is adopted, the lubricant supplied from the developing device 13 onto the photoreceptor drum 11 includes components that are supplied independently of the toner (toner that adheres to the electrostatic latent image and forms a toner image) supplied onto the photoreceptor drum 11 during the developing process. In particular, since the lubricant in this embodiment consists of non-charged particles, no electrostatic adhesion force is generated between it and the toner, which consists of charged particles (toner that is negatively charged in this embodiment). Therefore, the lubricant in this embodiment is not affected by the toner that moves to the photoreceptor drum 11 during the developing process, and continues to be supplied to the photoreceptor drum 11 almost uniformly across the entire width of the developing area as long as the photoreceptor drum 11 and the developing roller are rotating, both during developing and non-developing processes.

[0034] Therefore, in this embodiment, as shown in Figure 2, lubricant is continuously supplied from the developing device 13 to the photoreceptor drum 11, even in the widthwise region outside the maximum image width (hereinafter simply referred to as "maximum image width") where toner adheres due to the image forming operation.

[0035] In this embodiment, the development area width is wider than the maximum image width of the widest image that can be formed in this copier 1 (the image formed on paper with the maximum paper width usable by this copier 1), as shown in Figure 2. Therefore, even when forming the widest image in this copier 1, lubricant will be supplied from the development device 13 onto the photoreceptor drum 11 outside the maximum image width. In other words, filming by lubricant can occur over the entire development area width, which is wider than the maximum image width when forming the widest image that can be formed in this copier 1.

[0036] Filming tends to deteriorate, especially in the widthwise region where there is little toner coming in and out of contact members such as the cleaning blade 31. Therefore, deterioration of filming is likely to occur outside the maximum image width where toner does not adhere during image forming.

[0037] In conventional devices, if a strip-shaped scraping toner pattern is created that extends not only within the maximum image width but also outside the maximum image width, toner is supplied to the area outside the maximum image width where deterioration of filming is likely to occur. Therefore, with this conventional device, it is possible to suppress deterioration of filming that may occur throughout the entire development area width. However, the strip-shaped scraping toner pattern used in this conventional device adheres to the entire maximum image width. The maximum image width is the width area to which toner adheres during the image formation operation, and is therefore the width area where toner frequently enters and exits the contact member such as the cleaning blade 31, so deterioration of filming is already sufficiently suppressed. Therefore, even if toner is further supplied by the scraping toner pattern in the maximum image width where toner frequently enters and exits, there is almost no effect in suppressing deterioration of filming, and it results in wasted toner consumption.

[0038] Therefore, in this embodiment, as shown in Figure 2, during the image forming operation, a scraping toner pattern TP is created such that it is not created in the width region corresponding to the entire maximum image width during the image forming operation, but is created in the width region corresponding to the area outside the maximum image width. As a result, in the area outside the maximum image width where filming deterioration is likely to occur, toner is supplied by the scraping toner pattern TP, thereby suppressing filming deterioration. On the other hand, in the area within the maximum image width where filming deterioration is unlikely to occur in the first place, the toner pattern TP is not created over the entire area, so unnecessary toner consumption can be suppressed. As a result, unnecessary toner consumption can be suppressed while overall suppressing the filming deterioration that may occur in this copier 1.

[0039] Furthermore, in the conventional device described above, since the scraping toner pattern is created within the maximum image width during the image formation operation, it cannot be created at the same paper transport direction position (sub-scanning direction position) as the image formed during the image formation operation. Therefore, it is necessary to create the scraping toner pattern during the period before and after the image formation operation (the period during non-image formation operation) or in the inter-image region (inter-paper region) corresponding to the space between sheets of paper during the image formation operation. In this case, downtime occurs in order to allow time to create the scraping toner pattern during the period before and after the image formation operation, or the spacing between sheets of paper is widened in order to create the scraping toner pattern in the inter-image region (inter-paper region), resulting in a decrease in image productivity.

[0040] In contrast, the scraping toner pattern TP of this embodiment is not imaged in the width region corresponding to the entire maximum image width during the image formation operation. Therefore, as shown in Figure 2, the scraping toner pattern TP can be imaged at the same paper transport direction position (sub-scanning direction position) as the image formed during the image formation operation. Consequently, the occurrence of downtime and the decrease in image productivity mentioned above are suppressed.

[0041] In this embodiment, the scraping toner pattern TP is not formed in the width region corresponding to the entire maximum image width during the image formation operation. However, a scraping toner pattern may also be used in which the pattern is not formed in the width region corresponding to a part of the maximum image width during the image formation operation, but is formed in the width region corresponding to the remaining part of the maximum image width. Even in this case, it is possible to suppress unnecessary toner consumption compared to a conventional scraping toner pattern that is formed over the entire maximum image width.

[0042] Furthermore, the scraping toner pattern TP in this embodiment is a toner pattern that is imaged in a width region corresponding to a part outside the maximum image width during the image forming operation (outside the paper feed width during the image forming operation). However, it may also be a toner pattern that is imaged in a width region corresponding to the entire area outside the maximum image width (for example, a toner pattern that also extends within the paper feed width during the image forming operation). However, by imaged the scraping toner pattern TP in a width region corresponding to the outside the paper feed width during the image forming operation, it is possible to suppress toner staining on the paper P.

[0043] In other words, in the width region where the scraping toner pattern TP is imaged, the amount of toner adhering increases over time, which can lead to toner contamination at the location of the charging device 12 corresponding to that width region, potentially causing abnormal images such as vertical streaks to appear in that location. Furthermore, toner contamination can progress at the location of the developing device 13 corresponding to that width region (such as the entrance seal), and at the locations of the cleaning unit 15 and belt cleaning device 30 corresponding to that width region (such as the entrance seal), potentially causing abnormal images such as toner drops to appear in that location. As in this embodiment, by imaged in a width region corresponding to the outside of the paper feed width during the image formation operation, it is possible to suppress the formation of such abnormal images on the paper P.

[0044] Figure 3 illustrates another example of the formation position (width region) of the scraping toner pattern TP on the intermediate transfer belt 17. The example shown in Figure 3 illustrates how to form an image on paper with a paper width narrower than the maximum paper width usable by this copier 1 (narrow paper). In the example shown in Figure 3, as in the example in Figure 2, a scraping toner pattern TP is created such that, during the image formation operation, it is not created in the width region corresponding to the entire maximum image width during the image formation operation, but is created in the width region corresponding to the area outside the maximum image width. Therefore, it is possible to suppress unnecessary toner consumption while overall suppressing the deterioration of filming that may occur in this copier 1.

[0045] When forming an image on narrow paper, toner can be supplied to the area outside the maximum image width during the image formation operation on narrow paper, overlapping with the area within the maximum image width during other image formation operations on wider paper. Therefore, deterioration of filming is relatively unlikely in this overlapping area. However, even in this overlapping area, toner is not supplied during the image formation operation on narrow paper, so deterioration of filming is a concern.

[0046] Therefore, in the example shown in Figure 3, a scraping toner pattern TP is created that also forms an image in the overlapping area mentioned above. This also suppresses the deterioration of filming in areas that overlap with the maximum image width during other image forming operations on wider paper.

[0047] In this embodiment, as shown in the examples in Figures 2 and 3, pattern image control is performed to create a scraping toner pattern TP such that the width of the toner pattern increases as the maximum image width formed during the image formation operation decreases. This makes it possible to create a scraping toner pattern TP with an appropriate width according to the maximum image width formed during the image formation operation. In other words, even if the maximum image width formed during the image formation operation is different, it is possible to appropriately obtain the effect of suppressing the deterioration of filming while suppressing unnecessary toner consumption.

[0048] Figure 4 illustrates yet another example of the formation position (width region) of the scraping toner pattern TP on the intermediate transfer belt 17. The example shown in Figure 4, like the example in Figure 3, is an example of image formation on narrow paper that is narrower than the maximum paper width usable by this copier 1. In the example shown in Figure 4, during the image formation operation, a scraping toner pattern TP is created such that it is not created in the width region corresponding to the entire maximum image width during the image formation operation, but is created in the width region corresponding to the area outside the maximum image width. Therefore, it is possible to suppress unnecessary toner consumption while also suppressing the overall deterioration of filming that may occur in this copier 1.

[0049] Furthermore, in the example shown in Figure 3, a scraping toner pattern TP is created that also forms an image in the overlapping area, in order to suppress the deterioration of filming in the area that overlaps with the maximum image width during other image forming operations on wider paper. However, if, for example, another image forming operation on wider paper is performed before or after an image forming operation on narrow paper, sufficient toner is supplied to the overlapping area during the other image forming operation. In such cases, supplying toner to the overlapping area with the scraping toner pattern will have little effect in suppressing the deterioration of filming and will result in wasted toner consumption.

[0050] In the example shown in Figure 4, if an image forming operation on a wider sheet of paper is performed before or after an image forming operation on a narrow sheet of paper, a scraping toner pattern is used during the period when the image forming operation on the narrow sheet of paper is being performed, in which the image is not formed in the portion that overlaps with the maximum image width during the other image forming operation on the wider sheet of paper.

[0051] Specifically, in the example shown in Figure 4, a scraping toner pattern TP is created such that it is not created in the width region corresponding to the entire maximum image width during the image forming operation prior to the current image forming operation (for example, the one immediately preceding it), but is created in the width region corresponding to the area outside the maximum image width. This further reduces wasted toner consumption compared to creating a scraping toner pattern TP that is not created in the width region corresponding to the entire maximum image width during the current image forming operation, but is created in the width region corresponding to the area outside the maximum image width.

[0052] Alternatively, instead of the example in Figure 4, a scraping toner pattern TP may be created such that it is not imaged in the width region corresponding to the entire maximum image width during an image forming operation that occurs after the current image forming operation (for example, immediately afterward) (another image forming operation), but is imaged in the width region corresponding to the area outside the maximum image width. In this case as well, it is possible to further suppress wasted toner consumption.

[0053] In this embodiment, the image formation control of the scraping toner pattern TP is performed such that the less toner is consumed during the image formation operation (amount of toner consumed for image formation), the greater the toner consumed when forming the scraping toner pattern TP (amount of toner ejected). This is for the following reasons.

[0054] In this embodiment, a configuration is adopted in which a developer, which is a pre-mixed toner and lubricant, is supplied from the developer container 28 to the developing device 13. In such a configuration, when the amount of toner consumed during the image formation operation (amount of toner consumed for image formation) is small (for example, when an image with a relatively low image area ratio is formed), the amount of developer supplied from the developer container 28 to the developing device 13 (amount of developer supplied per unit travel distance of the intermediate transfer belt 17) is small. On the other hand, regardless of the amount of toner consumed during the image formation operation, the amount of lubricant supplied from the developing device 13 to the photoreceptor drum 11 (amount of lubricant consumed) is almost the same, and a certain amount or more of lubricant continues to be consumed. Consequently, when the amount of toner consumed during the image formation operation is small, the amount of lubricant supplied from the developer container 28 may become insufficient, and a problem may occur in which the amount of lubricant supplied from the developing device 13 to the photoreceptor drum 11 becomes insufficient.

[0055] In this embodiment, in order to suppress this problem, as described above, the image formation control of the scraping toner pattern TP is performed such that the less toner consumed during the image formation operation, the greater the toner consumed when forming the scraping toner pattern TP (toner ejection amount). As a result, even when the amount of toner consumed during the image formation operation is small, the amount of toner consumed by the scraping toner pattern TP (toner ejection amount) increases, resulting in an increase in the amount of developer supplied from the developer container 28 to the developing device 13. Therefore, the amount of lubricant supplied increases, and a shortage of lubricant supplied from the developing device 13 to the photoreceptor drum 11 is suppressed.

[0056] Figure 5 is a graph showing an example of the relationship between the image area ratio per unit travel distance and the toner consumption by the scraping toner pattern TP in this embodiment. As shown in Figure 5, the lower the image area ratio per belt travel distance (surface travel distance of the image carrier) of the image being formed, the less toner is consumed during the image formation operation. Therefore, pattern formation control is performed to increase the toner consumption (toner ejection amount) by the scraping toner pattern TP.

[0057] In particular, in the example shown in Figure 5, when the image area ratio per belt travel distance (hereinafter simply referred to as "image area ratio") is 5% or less, the toner consumption (toner discharge amount) by the scraping toner pattern TP is adjusted (changed) so that the total amount of toner consumed by image formation and the toner consumed by the toner pattern TP (toner discharge amount) (total toner adhering to the intermediate transfer belt 17) is approximately the same as the toner consumption by image formation (toner adhering to the intermediate transfer belt 17) when the image area ratio is 5%. As a result, the amount of developer replenished per belt travel distance when the image area ratio is 5% or less becomes approximately constant, and the minimum amount of lubricant to be replenished can be secured, thereby suppressing a shortage of lubricant supplied from the developing device 13 to the photoreceptor drum 11.

[0058] Methods for adjusting (changing) the toner consumption (toner ejection amount) by the scraping toner pattern TP include, for example, changing the length of the scraping toner pattern TP in the recording material transport direction (length in the sub-scanning direction). Alternatively, the widthwise length of the scraping toner pattern TP may be changed. Alternatively, the amount of toner deposited per unit area of ​​the scraping toner pattern TP may be changed. Furthermore, methods combining these methods, or methods combining these methods with other methods, may also be used.

[0059] Furthermore, it is preferable that the scraping toner pattern TP formed during the image formation operation is not formed in the area corresponding to the space between continuously fed sheets of paper (the inter-paper area), as shown in Figure 6. By preventing the scraping toner pattern TP from being formed in the inter-paper area, toner can be intermittently supplied to the contact member such as the cleaning blade 31, thereby suppressing excessive toner input to the contact member. This reduces the cleaning load.

[0060] Figure 7 is a flowchart showing an example of pattern image control for the scraping toner pattern TP. When the control unit 80 receives a print command and starts driving the intermediate transfer belt 17, it starts measuring the travel distance of the intermediate transfer belt 17 (S1). When the driving of the intermediate transfer belt 17 stops, 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 17, based on the measured travel distance of the intermediate transfer belt 17. Specifically, it calculates the required toner input amount by multiplying the travel distance of the intermediate transfer belt 17 by a coefficient. Then, it calculates the cumulative value of the required toner input amount by adding the calculated required toner input amounts (S2).

[0061] If the cumulative value exceeds the threshold (Yes in S3), a scraping toner pattern TP is formed when the intermediate transfer belt 17 is driven next. Then, the amount of toner consumed by the formed scraping toner pattern (amount of toner input to the cleaning blade) is subtracted from the cumulative value (S4).

[0062] The coefficient may be a constant value, or it may be changed, for example, between color image mode and monochrome image mode. This is because filming may be worse in color image mode than in monochrome image mode. In color image mode, the fixing temperature is higher than in monochrome image mode, and the number of motors in operation increases, which tends to raise the internal temperature of the machine. When the internal temperature rises, the amount of stick-slip of the cleaning blade 31 increases, which may worsen the filming. Also, if there is a lubricant application section on the surface of the photoreceptor drum 11, the amount of lubricant that becomes a component of the filming material adhering to the intermediate transfer belt 17 increases in color image mode than in monochrome mode. Therefore, filming may be worse in color image mode than in monochrome image mode.

[0063] 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, at the time of image formation (when the intermediate transfer belt is driven), 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.

[0064] For example, when there are many color image modes, the risk of film deterioration is higher than in the monochrome image mode as described above. However, when there are many color image modes, since the integrated value of the required toner input amount exceeds the threshold value at the running distance of the short intermediate transfer belt 17, the scraping toner pattern TP is formed at an early timing. On the other hand, when there are many monochrome image modes, film deterioration is less likely to occur compared to the color image mode. Therefore, when there are many monochrome image modes, the running distance at which the integrated value of the required toner input amount exceeds the threshold value becomes longer, and the scraping toner pattern TP is formed at a late timing.

[0065] In this way, by forming the scraping toner pattern based on the image mode, the scraping toner pattern can be formed at an appropriate timing, and waste toner consumption and deterioration of filming can be suppressed well.

[0066] In the above description, an embodiment in which the present invention is applied to an image forming apparatus of an intermediate transfer system has been described. However, the present invention can also be applied to an image forming apparatus of a direct transfer system that directly transfers the toner image on the photoreceptor drum to the paper as a recording material. For this direct transfer type image forming apparatus, the image carrier corresponds to the photoreceptor drum, and the cleaning member corresponds to the photoreceptor cleaning blade that cleans the surface of the photoreceptor.

[0067] What has been described above is an example, and each of the following aspects has a specific effect. [Aspect 1] The first embodiment is an image forming apparatus (e.g., a copier 1) that forms an image on a recording material (e.g., paper P) by developing apparatus 13 that uses a developer containing toner particles and lubricant particles, wherein the apparatus has control means (e.g., a control unit 80) that performs pattern forming control to form a toner pattern (e.g., a scraping toner pattern TP) that is not formed on the recording material using the toner particles during the image forming operation or during the period before the start or after the completion of the image forming operation, and the control means performs the pattern forming control such that the toner pattern is not formed in a width region corresponding to a part or all of the maximum image width formed during the image forming operation, but is formed in a width region corresponding to outside the maximum image width formed during the image forming operation. Some image forming apparatuses have lubricant particles attached to the latent image carrier for purposes such as suppressing the adhesion of toner additives to the latent image carrier and suppressing wear of the latent image carrier. In such image forming apparatuses, filming occurs, in which lubricant particles are fixed to the latent image carrier or intermediate transfer body (hereinafter referred to as "image carrier") by contact members such as cleaning members that come into contact with the image carrier. If filming deteriorates, problems such as poor cleaning and poor detection by the image sensor will occur. One method for supplying lubricant particles onto the image carrier is to use a developer containing toner particles and lubricant particles. In an image forming apparatus employing this method, lubricant particles can be supplied from the developer to the latent image carrier or to the intermediate transfer medium via the latent image carrier. However, some of the lubricant particles supplied from the developer to the latent image carrier are supplied independently of the toner particles supplied to the latent image carrier during the development process. Therefore, lubricant particles are supplied from the developer to the latent image carrier even in the width region outside the maximum image width (outside the maximum image width) where toner particles adhere due to the image forming operation (hereinafter simply referred to as "maximum image width"). This phenomenon occurs even when forming the widest possible image, because the width of the development region to which the developer is supplied from the developer to the latent image carrier is wider than the maximum image width when forming the widest possible image that can be formed by the image forming apparatus. Therefore, when using a developer containing toner particles and lubricant particles, filming by the lubricant particles may occur over the entire development area width, which is wider than the maximum image width when forming the widest image that can be formed by the image forming apparatus. Filming tends to worsen, especially in the widthwise region where there is little movement of toner particles into and out of the contact material. Therefore, filming deterioration is more likely to occur outside the maximum image width where toner particles do not adhere during image forming. In this case, conventional image forming apparatuses that create toner patterns that extend not only within the maximum image width but also outside the maximum image width (toner patterns that are not formed on the recording material) supply toner particles to the area outside the maximum image width where filming deterioration is likely to occur. Therefore, with conventional image forming apparatuses, it is possible to suppress filming deterioration that can occur throughout the entire width of the development area. However, conventional image forming apparatuses employ a toner pattern in which toner particles adhere to the entire maximum image width. Since the maximum image width is the width region in which toner particles adhere during the image forming operation, toner particles frequently enter and exit the contact material, and deterioration of filming is sufficiently suppressed. Therefore, supplying toner particles to the maximum image width using the toner pattern contributes little to suppressing deterioration of filming and can be said to result in wasted toner consumption. In this embodiment, the control means performs pattern image control to create a toner pattern such that it is not imaged in a width region corresponding to part or all of the maximum image width during the image forming operation, but is imaged in a width region corresponding to the area outside the maximum image width. As a result, in the area outside the maximum image width where deterioration of filming is likely to occur because toner particles do not adhere during the image forming operation, the deterioration of filming is suppressed by supplying toner particles through the toner pattern. On the other hand, in the area within the maximum image width where deterioration of filming is less likely to occur because toner particles adhere during the image forming operation, unnecessary toner consumption can be suppressed by not imageing a toner pattern in part or all of that area. As a result, it is possible to suppress unnecessary toner consumption while overall suppressing the deterioration of filming that may occur in the image forming apparatus.

[0068] [Second aspect] The second embodiment is characterized in that, in the first embodiment, the toner particles are charged particles and the lubricant particles are uncharged particles. According to this embodiment, since the lubricant particles in the developer are non-charged particles, no electrostatic adhesion force is generated between them and the toner particles, which are charged particles. Therefore, the lubricant particles can be supplied to the latent image carrier almost uniformly across the entire width of the development area during the image formation operation, without being affected by the toner particles that move to the latent image carrier during the development process. Thus, the amount of lubricant supplied to the latent image carrier is not affected by the amount of toner consumed by image formation (image area ratio, etc.), and a stable amount of lubricant particles can be supplied to the latent image carrier.

[0069] [Third aspect] The third embodiment is characterized in that, in the first or second embodiment, it has at least one of the following cleaning members: a cleaning member for cleaning the latent image carrier (for example, a cleaning member of the cleaning section 15), and a cleaning member for cleaning the intermediate transfer body (for example, an intermediate transfer belt 17) on which the image on the latent image carrier is intermediately transferred (for example, a cleaning blade 31). According to this method, the toner supplied by the toner pattern can be input to the contact points of the cleaning member that makes strong contact with the image carrier, thereby effectively suppressing deterioration of the filming process.

[0070] [Fourth aspect] The fourth embodiment is characterized in that, in any of the first to third embodiments, the control means performs the pattern image formation control such that the width of the toner pattern is increased as the maximum image width formed during the image formation operation becomes smaller. According to this, a toner pattern with an appropriate width corresponding to the maximum image width formed during the image formation operation can be created. Therefore, even if the maximum image width formed during the image formation operation differs, it is possible to appropriately suppress the deterioration of filming while suppressing unnecessary toner consumption.

[0071] [Fifth aspect] The fifth aspect is characterized in that, in any of the first to fourth aspects, the control means performs the pattern image formation control during the period of the image formation operation such that the toner pattern is not imaged in an area corresponding to the entire maximum image width formed during the image formation operation. This makes it possible to create a toner pattern at the same recording material transport direction position (sub-scanning direction position) as the image formed during the image formation operation. Therefore, there is no need to allocate time before and after the image formation operation to create the toner pattern, thus suppressing downtime. In addition, there is no need to create a toner pattern in the inter-image area (inter-paper area), thus suppressing the decrease in image productivity caused by widening the inter-paper area.

[0072] [Sixth aspect] The sixth aspect is characterized in that, in the fifth aspect, the control means performs the pattern imaging control so that the toner pattern is imaged only during the period of image forming operation. According to this, there is no need to allocate time before and after the image formation operation to create the toner pattern, thus suppressing downtime.

[0073] [Seventh aspect] The seventh embodiment is characterized in that, in any of the first to sixth embodiments, the device has a developer supply means for supplying the developer from a developer storage unit (e.g., a developer container 28) that stores the developer to the developing device 13, and the control means performs the pattern image control such that the less toner consumed during the image forming operation, the greater the toner consumed when the toner pattern is formed (e.g., the amount of toner ejected). In a configuration where a developer containing toner and lubricant is supplied from a developer reservoir to the developing device, when the amount of toner consumed during the image forming operation is small, the amount of developer supplied from the developer reservoir to the developing device is small. On the other hand, the amount of lubricant particles supplied from the developing device to the latent image carrier (lubricant consumption) is not affected by the amount of toner consumed during the image forming operation and continues to be consumed above a certain amount. Therefore, when the amount of toner consumed during the image forming operation is small, the amount of lubricant supplied from the developer reservoir may become insufficient, which can lead to a problem where the amount of lubricant supplied from the developing device to the latent image carrier is insufficient. According to this embodiment, the less toner is consumed during the image forming operation, the greater the toner consumption (toner ejection amount) due to the toner pattern, resulting in an increase in the amount of developer supplied from the developer reservoir to the developing device. Therefore, the amount of lubricant supplied increases, and the shortage of lubricant supplied from the developing device to the latent image carrier is suppressed.

[0074] [8th aspect] The eighth aspect is characterized in that, in the seventh aspect, the control means changes the amount of toner consumed when the toner pattern is imaged so that the amount of developer supplied per unit surface movement distance of the image carrier that carries the image is substantially constant. This ensures that the minimum amount of lubricant supplied is secured, thereby stably suppressing any shortage of lubricant supplied from the developing device to the latent image carrier.

[0075] [Ninth aspect] The ninth embodiment is characterized in that, in the seventh or eighth embodiment, the control means changes the amount of toner consumed when the toner pattern is imaged by changing the length of the toner pattern in the recording material transport direction. According to this, the amount of toner consumed when creating a toner pattern can be easily changed.

[0076] [Tenth aspect] The tenth embodiment is characterized in that, in any of the seventh to ninth embodiments, the control means changes the amount of toner consumed when the toner pattern is imaged by changing the widthwise length of the toner pattern. According to this, the amount of toner consumed when creating a toner pattern can be easily changed.

[0077] [Phase 11] The eleventh embodiment is characterized in that, in any of the seventh to tenth embodiments, the control means changes the amount of toner consumed when the toner pattern is imaged by changing the amount of toner deposited per unit area of ​​the toner pattern. According to this, the amount of toner consumed when creating a toner pattern can be easily changed. [Explanation of Symbols]

[0078] 1: Photocopier 3: Manuscript transport section 4: Manuscript reading unit 5: Output tray 6: Writing section 7:Paper feed section 8: Paper feed roller 9: Registroller 11: Photoconductor Drum 12: Charging device 13: Developing equipment 14: Primary transfer bias roller 15: Cleaning Department 17: Intermediate transfer belt 18: Secondary transfer roller 18A: Opposing rollers 20: Fixing device 28: Developer container 30: Belt cleaning device 31: Cleaning blade 40: Optical sensor 80: Control Unit TP: Scratch-off toner pattern [Prior art documents] [Patent Documents]

[0079] [Patent Document 1] Patent No. 6164232

Claims

1. An image forming apparatus that forms an image on a recording material by developing an agent containing toner particles and lubricant particles, wherein the image is formed on a latent image carrier using a developing apparatus, The system has control means for performing pattern forming control to form a toner pattern on the recording material using toner particles during the image forming operation or during the period before or after the start of the image forming operation, The control means performs the pattern image formation control such that the toner pattern is not imaged in the width region corresponding to the entire maximum image width formed during the image formation operation, but is imaged in the width region corresponding to the area outside the maximum image width formed during the image formation operation. The image forming apparatus is characterized in that the control means performs the pattern forming control such that the width of the toner pattern is increased as the maximum image width formed during the image forming operation becomes smaller.

2. In the image forming apparatus according to claim 1, An image forming apparatus characterized in that the toner particles are charged particles and the lubricant particles are uncharged particles.

3. In the image forming apparatus according to claim 1 or 2, An image forming apparatus characterized by having at least one of the following cleaning members: a cleaning member for cleaning the latent image carrier, and a cleaning member for cleaning an intermediate transfer body on which an image on the latent image carrier is intermediately transferred.

4. In the image forming apparatus according to any one of claims 1 to 3, The image forming apparatus is characterized in that the control means performs the pattern forming control so that the toner pattern is formed only during the period of image forming operation.

5. In the image forming apparatus according to any one of claims 1 to 4, The developing apparatus has a developer supply means for supplying the developer from a developer storage section that stores the developer, The image forming apparatus is characterized in that the control means performs the pattern forming control such that the less toner is consumed during the image forming operation, the more toner is consumed when forming the toner pattern.

6. In the image forming apparatus according to claim 5, The control means is characterized by changing the amount of toner consumed when the toner pattern is formed so that the amount of developer supplied per unit surface movement distance of the image carrier that holds the image is substantially constant.

7. In the image forming apparatus according to claim 5 or 6, The control means is characterized by changing the amount of toner consumed when the toner pattern is imaged by changing the length of the toner pattern in the recording material transport direction.

8. In the image forming apparatus according to any one of claims 5 to 7, The control means is characterized by changing the amount of toner consumed when the toner pattern is imaged by changing the widthwise length of the toner pattern.

9. In the image forming apparatus according to any one of claims 5 to 8, The control means is characterized by changing the amount of toner consumed when the toner pattern is imaged, by changing the amount of toner deposited per unit area of ​​the toner pattern.

Images