Image forming apparatus

Abstract

To appropriately dispose of deteriorated toner.SOLUTION: An image forming apparatus 100 comprises: a waste dot count calculation unit 172 that, every time an image forming operation is performed, calculates a disposal amount that is an amount of developer to be disposed of from each of a plurality of image forming units; a waste dot count update unit 173 that, in each of the plurality of image forming units, calculates a total disposal amount that is the accumulation of the disposal amounts; a deteriorated toner disposal execution checking unit 174 that determines whether or not the total disposal amount of a first image forming unit included in the plurality of image forming units exceeds a first threshold; and a deteriorated toner disposal execution unit 175 that performs disposal of developer from the first image forming unit when the total disposal amount of the first image forming unit is determined to exceed the first threshold. When the total disposal amount of the first image forming unit exceeds the first threshold, and further a second image forming unit satisfies a predetermined condition, the deteriorated toner disposal execution unit 175 performs disposal of developer from the second image forming unit.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] In electrophotographic image forming devices, deteriorated toner accumulates inside the device during use. A major cause of this is when the density of the toner consumed for printing and correction operations is insufficient for the printed image, and the toner comes into contact with a member charged to a high voltage for a long period of time.

[0003] Since this deteriorated toner is a factor that causes a decrease in image quality, in image forming apparatuses, the deteriorated toner in the developing device is ejected onto a photosensitive drum and collected in a waste toner collection container in the image forming unit.

[0004] When the print data coverage is high, the toner is developed before it deteriorates, so deteriorated toner is less likely to occur. Therefore, when discarding deteriorated toner from the entire surface of the photosensitive drum, deteriorated toner may also be discarded in areas where the print data coverage is high and the toner is not deteriorated.

[0005] In this regard, the image forming device described in Patent Document 1 calculates the duty value of each area of ​​the photosensitive drum divided into n parts when a predetermined condition is satisfied, and discards degraded toner from areas whose duty value is smaller than a reference value, thereby preventing toner from being wasted. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-242394 A Summary of the Invention [Problem to be solved by the invention]

[0007] However, with conventional technology, even if the DUTY value is close to the reference value, if it is not equal to or greater than the reference value, the degraded toner is not discarded, and images are formed with a certain amount of degraded toner accumulated until the next time, which may result in a deterioration in the quality of the formed image.

[0008] Therefore, one or more aspects of the present disclosure aim to enable proper disposal of deteriorated developer. [Means for solving the problem]

[0009] According to an aspect of the present disclosure, there is provided an image forming apparatus including a plurality of image forming units each including an image carrier, a charging unit for uniformly charging the image carrier, and a developing unit for forming a developer image by attaching a developer to an electrostatic latent image formed on the image carrier, a plurality of exposure units for forming the electrostatic latent image by exposing the image carrier of each of the plurality of image forming units, a transfer unit for transferring the developer image formed by the plurality of image forming units to a medium, and a fixing unit for fixing the developer image to the medium, a waste amount calculation unit for calculating, in each of the plurality of image forming units, a waste amount which is an amount of the developer to be discarded from each of the plurality of image forming units each time an image forming operation for forming an image on the medium is performed using the plurality of image forming units, the plurality of exposure units, the transfer unit, and the fixing unit, a waste amount accumulation unit for calculating, in each of the plurality of image forming units, a total waste amount which is an accumulation of the waste amounts, and a waste amount calculation .... and a disposal execution unit that, when it is determined that the total discard amount of the first image forming unit exceeds the first threshold, controls a first exposure unit, among the multiple exposure units, that exposes the first image forming unit to light, and the first image forming unit to form a developer image for disposal, thereby discarding the developer from the first image forming unit. When it is determined that the total discard amount of the first image forming unit exceeds the first threshold, the disposal execution determination unit determines whether a second image forming unit included in the multiple image forming units excluding the first image forming unit satisfies a predetermined condition, and when it is determined that the second image forming unit satisfies the predetermined condition, the disposal execution unit controls a second exposure unit, among the multiple exposure units, that exposes the second image forming unit to light, and the second image forming unit to form a developer image for disposal, thereby discarding the developer from the second image forming unit. Effect of the Invention

[0010] According to one or more aspects of the present disclosure, depleted developer can be appropriately disposed of. [Brief description of the drawings]

[0011] [Figure 1]1 is a cross-sectional view illustrating a schematic configuration of a main part of an image forming apparatus according to first and second embodiments. [Diagram 2] FIG. 2 is a cross-sectional view illustrating a schematic configuration of an image forming unit and a transfer unit. [Diagram 3] FIG. 1 is a block diagram showing a schematic configuration of an image forming apparatus according to first and second embodiments. [Figure 4] 4 is a schematic diagram showing an example of programs and data stored in a storage unit in the first embodiment. FIG. [Diagram 5] FIG. 2 is a block diagram illustrating a schematic configuration of a control unit 170 in the first embodiment. [Figure 6] 1A and 1B are block diagrams illustrating an example of a hardware configuration. [Figure 7] 13 is a schematic diagram showing an example of an image pattern when degraded toner is discarded in all areas. FIG. [Figure 8] 11A and 11B are schematic diagrams showing example image patterns when degraded toner is discarded in a single area. [Figure 9] 10 is a flowchart showing an operation performed when a print instruction is received. [Figure 10] 10 is a flowchart showing a deteriorated toner disposal execution process. [Figure 11] 5 is a flowchart showing a process for determining whether or not to discard deteriorated toner in the first embodiment. [Figure 12] This is a table showing the number of times a first photosensitive drum is printed, the cumulative single-area waste dot count formed on the first photosensitive drum when a printing operation corresponding to that number of times is performed, and the cumulative total waste dot count of the entire area of ​​the first photosensitive drum in embodiments 1 and 2. [Figure 13] In embodiment 1, this is a table showing the number of times the second photosensitive drum is printed, the cumulative single-area waste dot count formed on the second photosensitive drum when a printing operation corresponding to that number of times is performed, and the cumulative total waste dot count of the entire area of ​​the second photosensitive drum. [Figure 14] 11 is a schematic diagram showing an example of programs and data stored in a storage unit in the second embodiment. FIG. [Figure 15] FIG. 11 is a block diagram illustrating a schematic configuration of a control unit in the second embodiment. [Figure 16] 11 is a flowchart showing a process for determining whether or not to discard deteriorated toner in the second embodiment. [Figure 17] In embodiment 2, this is a table showing the number of times of printing on the second photosensitive drum, the cumulative single-area waste dot count formed on the second photosensitive drum when a printing operation corresponding to that number of times is performed, and the cumulative total waste dot count of the entire area of ​​the second photosensitive drum. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Embodiment 1 FIG. 1 is a cross-sectional view that illustrates a schematic configuration of a main part of an image forming apparatus 100 according to the first embodiment. The medium storage tray 101 stores media such as paper. The pickup roller 102 rotates to pick up one of the upper media stored in the media storage tray 101 and feeds out that one medium.

[0013] The single medium is transported to image forming units 110K, 110Y, 110M, and 110C by transport roller pairs 103, 104, and 105. At that time, medium detection sensors 106, 107, and 108 detect the position of the medium.

[0014] Image forming units 110K, 110Y, 110M, and 110C are image forming units that include an image carrier, a charging section that uniformly charges the image carrier, and a developing section that forms a developer image by adhering developer to the electrostatic latent image formed on the image carrier. The image forming units 110K, 110Y, 110M, and 110C have the same configuration, except that the colors of the toners used as developers are different. In addition, in Fig. 1, the capital letters "K", "Y", "M", and "C" added to the end of the reference numerals indicate configurations corresponding to "black", "yellow", "magenta", and "cyan", respectively. Therefore, in the following description, when there is no need to distinguish the color, the capital letters "K", "Y", "M", and "C" added to the end of the reference numerals may be omitted.

[0015] The image forming units 110K, 110Y, 110M, and 110C are associated with LED heads 118K, 118Y, 118M, and 118C, which are exposure units that expose the image forming units 110K, 110Y, 110M, and 110C, respectively. The LED heads 118K, 118Y, 118M, and 118C expose the image carriers of the corresponding image forming units 110K, 110Y, 110M, and 110C to light, thereby forming electrostatic latent images.

[0016] A transfer unit 120 is provided below the image forming unit 110, and the toner image formed by the image forming unit 110 is transferred by the transfer unit 120 onto a medium that has been conveyed thereto.

[0017] The toner image is fixed to the medium by applying heat and pressure using a fixing unit 130 acting as a fixing device. The medium on which the toner image has been fixed is transported to a medium collection tray 141 by a pair of transport rollers 140. At that time, medium detection sensors 142 and 143 detect the position of the medium. The medium stacking tray 141 stacks the transported media.

[0018] When images are formed on both sides of a single medium, the single medium is transported again upstream of the image forming unit 110 by transport roller pairs 144, 145, 146, and 147. At that time, medium detection sensors 148 and 149 detect the position of the medium.

[0019] FIG. 2 is a cross-sectional view that illustrates a schematic configuration of the image forming unit 110 and the transfer unit 120. As shown in FIG. The image forming unit 110 includes a photosensitive drum 111, a charging roller 112, a supply roller 113, a developing roller 114, a cleaning blade 115, and a drum waste toner collection container 116.

[0020] The photosensitive drum 111 is an image carrier that carries an image. The charging roller 112 is a charging unit that applies a negative voltage to the photosensitive drum 111 to uniformly charge the photosensitive drum 111 . As shown in FIG. 1, an LED head 118 serving as an exposure unit arranged above the photosensitive drum 111 exposes the uniformly charged photosensitive drum 111, thereby forming an electrostatic latent image on the photosensitive drum 111.

[0021] The supply roller 113 is a supply unit that supplies toner from a toner cartridge 117 serving as a developer container to the developing roller 114 . The developing roller 114 is a developing unit that is applied with a negative voltage and causes toner to adhere to the electrostatic latent image formed on the photosensitive drum 111, thereby forming a toner image.

[0022] The toner image formed on the photosensitive drum 111 is transferred onto the conveyed medium by a positive voltage applied by a transfer roller 121 of a transfer unit 120 .

[0023] Residual toner remaining on the photosensitive drum 111 is scraped off by a cleaning blade 115 . The cleaning blade 115 is a disposal unit that scrapes off the waste toner image, which is a waste developer image, and discards the waste toner. The drum waste toner collection container 116 is a container for collecting and storing residual toner or waste toner remaining on the photosensitive drum 111 in the printing process or in a deteriorated toner disposal process described later.

[0024] The transfer unit 120 includes a transfer roller 121 as a transfer section, a transfer belt 122, a belt cleaning blade 123, and a belt waste toner collection container .

[0025] The transfer belt 122 is disposed opposite the image forming unit 110, and transfers a toner image onto the transported medium with a positive voltage from the transfer roller 121. In other words, the transfer roller 121 transfers the toner image formed on the photosensitive drum 111 onto the medium. The belt cleaning blade 123 scrapes off waste toner conveyed from the transfer belt 122 in a deteriorated toner disposal process, which will be described later, and serves as a container for storing the waste toner.

[0026] FIG. 3 is a block diagram showing a schematic configuration of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 includes a storage unit 150, a control unit 170, an input unit 181, a display unit 182, and an image forming main body 183.

[0027] The storage unit 150 stores data and programs necessary for processing by the image forming apparatus 100 . FIG. 4 is a schematic diagram showing an example of programs and data stored in storage unit 150 in the first embodiment. The memory unit 150 stores a program, an all-area deteriorated toner discard slice value, an all-area deteriorated toner discard execution dot count, a single-area deteriorated toner discard slice value, a single-area deteriorated toner discard execution dot count, an all-area dot count, a drum count progress, an all-area discard threshold dot count, an all-area discard dot count cumulative, a single-area dot count, a single-area discard threshold dot count, a single-area discard dot count, a single-area discard dot count cumulative, a discard execution flag, a maximum value of the single-area discard dot count cumulative, and a discard dot count percentage value.

[0028] It is desirable that the program, all-area deteriorated toner disposal slice value, all-area deteriorated toner disposal execution dot count, single-area deteriorated toner disposal slice value and single-area deteriorated toner disposal execution dot count are stored in a permanent storage unit that can permanently store data, such as a ROM (Read Only Memory).

[0029] In addition, it is desirable that the total area dot count, drum count progress, total area discard threshold dot count, total area discard dot count, total area discard dot count cumulative, single area dot count, single area discard threshold dot count, single area discard dot count, total single area discard dot count cumulative, discard execution flag, maximum value of total single area discard dot count cumulative, and discard dot count percentage value are stored in a temporary storage unit that can temporarily store data, such as a RAM (Random Access Memory) or the like.

[0030] Returning to FIG. 3, the control unit 170 controls the processing in the image forming apparatus 100 . FIG. 5 is a block diagram showing a schematic configuration of control unit 170 in the first embodiment. The control unit 170 includes an image formation management unit 171 , a waste dot count calculation unit 172 , a waste dot count update unit 173 , a deteriorated toner disposal execution check unit 174 , a deteriorated toner disposal execution unit 175 , and an LED head light amount adjustment unit 176 .

[0031] The image formation management unit 171 controls an image formation main body 183, which will be described later, to control an image forming operation, which is an operation of forming an image on a medium.

[0032] The waste dot count calculation unit 172 is a waste amount calculation unit that calculates the waste amount, which is the amount of toner to be discarded from each of the image forming units 110, for each of the image forming units every time an image forming operation is performed. As described later, the surface of the photosensitive drum 111 is divided into a plurality of areas in the main scanning direction and managed. The waste dot count calculation unit 172 calculates, for each of the plurality of areas, a single area waste amount, which is the amount of developer to be discarded from each of the plurality of areas, every time an image forming operation is performed.

[0033] The waste dot count update section 173 is a waste amount accumulating section that calculates a total waste amount, which is the accumulated total of the waste amounts calculated by the waste dot count calculation section 172 in each of the multiple image forming units 110 . Further, the waste dot count update section 173 calculates, for each of the plurality of image forming units 110, a single area total waste amount which is a cumulative total of the single area waste amounts in each of the plurality of areas.

[0034] In addition, when degraded toner is discarded, the discard dot count update unit 173 subtracts the amount of discarded toner from the single area total discard amount of the area where the discard was performed, and also subtracts that amount of toner from the total discard amount of the image forming unit 110 that includes that area.

[0035] The deteriorated toner disposal execution check unit 174 is a disposal execution determination unit that determines whether or not to discard deteriorated toner. For example, the deteriorated toner disposal execution check unit 174 determines whether the total disposal amount of a first image forming unit 110 (also called a first image forming section), which is one of the multiple image forming units 110, exceeds a first threshold value.

[0036] Then, when it is determined that the total amount of toner to be discarded of the first image forming unit 110 exceeds the first threshold, the deteriorated toner disposal execution check unit 174 determines whether or not the second image forming unit 110, which is one of the image forming units 110 included in the plurality of image forming units 110 excluding the first image forming unit 110, satisfies a predetermined condition. When the second image forming unit 110 satisfies the predetermined condition, the deteriorated toner disposal execution check unit 174 determines to discard the deteriorated toner of the second image forming unit 110. Here, the predetermined condition is that the single area discard amount exceeds a predetermined second threshold value.

[0037] Furthermore, if none of the areas of the second image forming unit satisfy the predetermined condition, the deteriorated toner disposal execution check unit 174 identifies one or more areas of the second image forming unit that have the maximum single-area total disposal amount, and then determines to discard deteriorated toner from the identified one or more areas.

[0038] The deteriorated toner disposal execution unit 175 is a disposal execution unit that, when it is determined that the total disposal amount of the first image forming unit 110 exceeds a first threshold, controls the first LED head 118, of the multiple LED heads 118, that exposes the first image forming unit 110 and the first image forming unit 110 to form a disposal developer image, thereby disposing of toner from the first image forming unit.

[0039] In addition, when it is determined that the second image forming unit 110 satisfies the predetermined conditions, the deteriorated toner disposal execution unit 175 controls the second LED head 118, among the multiple LED heads 118, that exposes the second image forming unit 110 and the second image forming unit 110 to form a developer image for disposal, thereby disposing of toner from the second image forming unit 110. Here, when the deteriorated toner disposal execution unit 175 determines that the single area disposal amount of one area included in the multiple areas of the second image forming unit 110 exceeds the second threshold value, it discards toner from that one area by forming a disposal developer image in that one area.

[0040] Furthermore, when none of the multiple areas of the second image forming unit satisfy the predetermined conditions, if the deteriorated toner disposal execution check unit 174 identifies one or more areas among the multiple areas of the second image forming unit 110 in which the single-area total disposal amount is the maximum value, the deteriorated toner disposal execution unit 175 controls the second LED head 118 and the second image forming unit 110 to form a disposal developer image in each of the identified one or more areas, thereby disposing of toner from the one or more areas. In this case, the deteriorated toner disposal execution unit 175 discards the amount of toner corresponding to the maximum value from each of the one or more areas. Specifically, the deteriorated toner disposal execution unit 175 instructs the LED head light amount adjustment unit 176 to adjust the amount of light from the second LED head 118, thereby discarding the amount of toner corresponding to the maximum value from each of the one or more areas.

[0041] The LED head light amount adjustment unit 176 adjusts the amount of light from the LED head 118 .

[0042] 3, the communication unit 180 communicates with other devices. For example, the communication unit 180 receives print data, which is image formation data indicating an image to be formed on a medium, from other devices via a network. The input unit 181 receives operations from the user. The display unit 182 displays various screens.

[0043] The image forming body 183 includes the elements shown in FIG. 1, and forms an image on the medium by transporting the medium, transferring a toner image to the medium, and fixing the transferred toner image to the medium.

[0044] A part or the whole of the control unit 170 described above can be configured, for example, as shown in Fig. 6(A), by a memory 10 and a processor 11 such as a CPU (Central Processing Unit) that executes a program stored in the memory 10. Such a program may be provided through a network, or may be provided by being recorded on a recording medium. That is, such a program may be provided, for example, as a program product.

[0045] In addition, a part or all of the control unit 170 may be configured with a processing circuit 12 such as a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), for example, as shown in FIG. 6(B). As described above, the control unit 170 can be configured with a processing circuit network.

[0046] The communication unit 180 can be configured with a communication interface such as a NIC (Network Interface Card). The input unit 181 can be configured with an input interface such as a touch panel or operation keys. The display unit 182 can be configured with a display such as a touch panel or a display panel.

[0047] Next, the deteriorated toner discarding process in the first embodiment will be described. The control unit 170 applies a negative voltage to the supply roller 113 and the development roller 114, thereby moving the toner supplied from the toner cartridge 117 to the photosensitive drum 111. However, once the toner is charged, it deteriorates over time.

[0048] Here, if the print duty is the ratio of the print rate to the entire paper, for example, if there is a lot of high duty printing (image formation) where the print rate (image formation rate) of the entire paper as a medium is high, the toner that has been charged once is immediately used for printing, so there is a high possibility that it will be used before it deteriorates. On the other hand, if there is a lot of low duty printing where the print rate of the entire paper is low, it takes a long time for the toner that has been charged once to be used for printing, and there is a high possibility that it will deteriorate.

[0049] Here, the number of dots required for printing will be explained using the dot count, which is the actual number of dots divided by a predetermined value, because the value will be very large if the actual number of dots is used for calculation. The predetermined value here is "8192 (=2 13 ) but is not limited to this number.

[0050] For example, when printing on A4 paper with a print duty of 5%, the actual number of dots is 6,488,064, but the dot count is 792 = (6,488,064 ÷ 8,192). Therefore, when the print duty is 1%, the dot count is 158.4 (≒ 792 ÷ 5).

[0051] The drum count is defined as the average number of rotations of the photosensitive drum 111 when printing one predetermined medium (here, for example, A4). Furthermore, the slice value is a print duty (%) per drum count. It should be noted that one photosensitive drum 111 is divided into n areas (n is a positive integer equal to or greater than 2) in a direction perpendicular to the direction of rotation (also called the main scanning direction). Hereinafter, "all areas" refers to all areas into which one photosensitive drum 111 is divided.

[0052] First, the process for one photosensitive drum 111 as a whole will be described. In one printing operation (image forming operation), a slice value serving as a threshold value for determining whether or not the toner in one photosensitive drum 111 deteriorates to the extent that it needs to be discarded is set as an "all-area deteriorated toner discard slice value S." Further, the advance (increment) of the drum count of one photosensitive drum 111 in one printing operation is defined as "drum count advance O in printing (image formation)." Furthermore, the dot count serving as a threshold for determining whether or not the toner in one photosensitive drum 111 has deteriorated to the extent that it needs to be discarded in one printing operation is set as the "all area discard threshold dot count SL." The dot count printed on one photosensitive drum 111 in one printing operation is defined as the "total area dot count D," and the dot count of degraded toner that is generated in one printing operation and must be discarded is defined as the "total area discard dot count WL."

[0053] In the above definitions, the "all area discard threshold dot count SL" and the "all area discard dot count WL" are calculated by the following equations (1) and (2). SL=158.4×S×O (1) WL=SL-D (2)

[0054] This will be explained using a specific example. If the entire area deteriorated toner waste slice value S is "1.5%", the dot count D in the entire area in one printing operation is "95.04", and the drum count advance O in that one printing operation is "2", the values ​​of SL and WL are calculated using the following equations (3) and (4), respectively. SL=158.4×1.5×2=475.2 (3) WL=475.2-95.4=380.16 (4)

[0055] In other words, the total area waste dot count WL, which corresponds to the amount of toner to be discarded in one printing operation, is “380.16.” In other words, the total area waste dot count WL corresponds to the waste amount. The above calculations are performed by the discard dot count calculation unit 172, and the discard dot count update unit 173 adds the calculated WL to the total discard dot count of all areas stored in the storage unit 150. In other words, the total discard dot count of all areas corresponds to the total discard amount.

[0056] Incidentally, the "all-area deteriorated toner discard slice value S" is a value that is pre-stored in the storage unit 150. Meanwhile, the "drum count progress O in printing (image formation)", "all-area discard threshold dot count SL", "all-area dot count D" and "all-area discard dot count WL" are values ​​that are calculated by the discard dot count calculation unit 172 based on the print data when print data corresponding to one printing operation is received.

[0057] As described above, if the all area dot count D in the printing operation is larger than the all area discard threshold dot count SL, the all area discard dot count WL will be smaller. On the other hand, if the all area dot count D in the printing operation is smaller than the all area discard threshold dot count SL, the all area discard dot count WL will be larger.

[0058] In addition, the all-area deteriorated toner discard execution dot count corresponding to the amount of toner to be discarded in one deteriorated toner discard operation is determined in advance and stored in storage unit 150 .

[0059] Here, the all-area deteriorated toner discard execution dot count is determined as follows. The width of LED head 118 of image forming apparatus 100 capable of printing on A4 medium (in other words, the main scanning width) is assumed to be 9,984 dots. In addition, in the image forming apparatus 100, when performing a deteriorated toner disposal operation to dispose of deteriorated toner in all areas, a 50% pattern (e.g., 1, 0, 1, 0, ...) is used in the main scanning direction, as shown in Figure 7. In this case, in the LED head 118, 4,992 dots of degraded toner are discarded per line. In the image forming apparatus 100, if the deteriorated toner is discarded for 1,364 lines in the sub-scanning direction in the deteriorated toner discarding operation, then 6,809,088 dots of deteriorated toner are discarded in one deteriorated toner discarding operation. When this is converted into a dot count, the all-area deteriorated toner discard execution dot count CD is calculated as shown in the following formula (5). CD=6,809,088÷8,192=831 (5) Here, the all-area deteriorated toner discard execution dot count CD is also referred to as one unit of all-area toner discard. The all-area deteriorated toner discard execution dot count CD corresponds to a first threshold value.

[0060] At a timing such as before printing, the deteriorated toner discard execution check unit 174 checks whether the total discard dot count for all areas has reached the total deteriorated toner discard execution dot count for all areas.

[0061] Next, one photosensitive drum 111 is divided into n areas, and processing related to the divided areas will be described. The number of divisions is n, and the slice value serving as a threshold value for determining whether or not toner deteriorates to the point of needing disposal in a single area divided from one photosensitive drum 111 during one printing operation is defined as the "single area deteriorated toner disposal slice value S#." In addition, the dot count used as a threshold for determining whether or not toner in a single area divided from one photosensitive drum 111 during one printing operation has deteriorated to the point where it needs to be discarded is referred to as the "single area discard threshold dot count SL#." In one printing operation, the dot count of printing (image formation) in each area divided from one photosensitive drum 111 is defined as the "single area dot count D#," and the dot count of degraded toner to be discarded in each area divided from one photosensitive drum 111 in one printing operation is defined as the "single area waste dot count WL#." In other words, the single area waste dot count WL# corresponds to the single area waste amount.

[0062] In the above definitions, the "single area discard threshold dot count SL#" and the "single area discard dot count WL#" are calculated by the following expressions (6) and (7). SL#=158.4÷n×S#×O (6) WL#=SL#-D# (7)

[0063] This will be explained using a specific example. The number of areas divided from one photosensitive drum 111 is six, in other words, one photosensitive drum 111 is divided into a first area to a sixth area. In addition, if the single area deteriorated toner waste slice value S# is "1.5%," the dot count D# in the first area in one printing operation is "15", and the drum count advance O in that one printing operation is "2", then the SL# and WL in that first area are calculated using the following equations (8) and (9), respectively. SL#=158.4÷6×1.5×2=79.2 (8) WL#=79.2-15=64.2 (9)

[0064] The above WL# is calculated for each area divided from one photosensitive drum 111, and the calculated value is added to the single area discard dot count cumulative total for each area. In other words, the single area discard dot count cumulative total corresponds to the single area total discard amount.

[0065] In addition, a single area deteriorated toner disposal execution dot count CD# corresponding to the amount of toner to be disposed of in a single area divided from one photosensitive drum 111 in one deteriorated toner disposal operation is determined in advance and stored in memory unit 150.

[0066] Here, the single area deteriorated toner discard execution dot count CD# is a value obtained by dividing the all area deteriorated toner discard execution dot count CD by the division number n, as shown in the following formula (10). CD#=CD÷n (10) Specifically, it is expressed by the following formula (11). CD#=6,809,088÷8192÷6≒138.5 (11) Here, 138.5 dot counts is one unit of toner disposal when divided into 6. The single area deteriorated toner disposal execution dot count CD# also corresponds to the second threshold value. When discarding deteriorated toner in only a single area (here, the first area) divided into six, the electrostatic latent image pattern repeating 1, 0, 1, 0, . . . in the main scanning direction of the photosensitive drum 111 will be as shown in FIG.

[0067] FIG. 9 is a flowchart showing the operation performed when the control unit 170 receives a print instruction via the communication unit 180. When the communication unit 180 receives print data (S10), the image forming management unit 171 instructs the deteriorated toner disposal execution check unit 174 to perform deteriorated toner disposal execution processing.

[0068] When such an instruction is received, the deteriorated toner disposal execution check unit 174 executes the deteriorated toner disposal execution process (S11), which will be described later.

[0069] When the deteriorated toner disposal execution process in step S11 is completed, the image formation management unit 171 controls the image formation main body 183 to start printing (S12). Then, when the printing started in step S12 is completed (S13), the image formation management section 171 instructs the waste dot count calculation section 172 to calculate the waste dot count.

[0070] When such an instruction is received, the discard dot count calculation unit 172 calculates the discard dot count (S14). Specifically, waste dot count calculation section 172 receives from image formation management section 171 the total area dot count D for the current printing and the drum count progress O for the current printing, calculates the total area waste dot count, and adds it to the total area waste dot count accumulated stored in storage section 150. In addition, waste dot count calculation section 172 receives from image formation management section 171 the single area dot count D# for the current printing, calculates the single area waste dot count, and adds it to the single area waste dot count accumulated stored in storage section 150.

[0071] FIG. 10 is a flowchart showing the deteriorated toner disposal execution process. The deteriorated toner disposal execution check unit 174 checks whether or not there is a photosensitive drum 111 whose total area disposal dot count exceeds the total area deteriorated toner disposal execution dot count among all the photosensitive drums 111 (S21). If there is such a photosensitive drum 111, the process proceeds to step S22, and if there is no such photosensitive drum 111, the process ends since the deteriorated toner disposal execution process is not necessary.

[0072] In step S22, the deteriorated toner disposal execution check unit 174 performs a deteriorated toner disposal execution determination for one photosensitive drum 111. The process here will be described later.

[0073] When the deteriorated toner disposal execution determination in step S22 is completed for one photosensitive drum 111, the deteriorated toner disposal execution check unit 174 determines (S23) whether the deteriorated toner disposal execution determination is completed for all photosensitive drums 111. If the deteriorated toner disposal execution determination is not completed for all photosensitive drums 111 and there is a photosensitive drum 111 for which the deteriorated toner disposal execution determination has not been performed (NO in S23), the process proceeds to step S24, and if the deteriorated toner disposal execution determination is completed for all photosensitive drums 111 (YES in S23), the process proceeds to step S25.

[0074] In step S24, the deteriorated toner disposal execution check unit 174 changes the determination target to one photosensitive drum 111 for which the deteriorated toner disposal execution determination has not been completed. Then, the process returns to step S22.

[0075] On the other hand, in step S25, the deteriorated toner disposal execution check unit 174 instructs the deteriorated toner disposal execution unit 175 to dispose of deteriorated toner for the areas where the disposal execution flag is on, and in response to such instruction, the deteriorated toner disposal execution unit 175 disposes of deteriorated toner for the areas where the disposal execution flag is on.

[0076] When the disposal of deteriorated toner in step S25 is completed, the disposal dot count update unit 173 subtracts the single area deteriorated toner disposal execution dot count used in this deteriorated toner disposal from the single area disposal dot count cumulative count stored in the memory unit 150, and recalculates the total area disposal dot count cumulative count (S26).

[0077] FIG. 11 is a flowchart showing the deteriorated toner disposal execution determination process in the first embodiment. The deteriorated toner disposal execution check unit 174 identifies the largest value among the single-area waste dot count cumulative values ​​of one of the photosensitive drums 111 being judged, and stores the identified value in the memory unit 150 as the maximum value of the single-area waste dot count cumulative values ​​(S30).

[0078] The deteriorated toner discard execution check unit 174 judges whether the maximum value specified in step S30 exceeds the single area deteriorated toner discard execution dot count (S31). If the maximum value exceeds the single area deteriorated toner discard execution dot count (YES in S31), the process proceeds to step S32, and if the maximum value does not exceed the single area deteriorated toner discard execution dot count (NO in S31), the process proceeds to step S33.

[0079] In step S32, the deteriorated toner disposal execution check unit 174 turns on the disposal execution flag for all areas included in the single photosensitive drum 111 being judged, for which the single area disposal dot count cumulative total exceeds the single area deteriorated toner disposal execution dot count.

[0080] On the other hand, in step S33, the deteriorated toner discard execution check unit 174 calculates a ratio value RT of the discard dot count by the following formula (12). RT = (maximum value of single area discard dot count) ÷ (single area degraded toner discard execution dot count) (12)

[0081] Next, the deteriorated toner discard execution check unit 174 turns on the discard execution flag of the area corresponding to the maximum value of the single area discard dot count (S34).

[0082] Next, the LED head light amount adjustment unit 176 multiplies the light amount setting of the LED head 118 by the ratio value of the discard dot count to set the light amount when performing exposure (S35). For the areas where the discard execution flag is turned on in step S34, exposure is performed with the set light amount when performing toner discard in step S25 of FIG.

[0083] Next, the operation of the flowcharts shown in FIGS. 10 and 11 will be described using a concrete example. Here, an example will be described in which the image forming apparatus 100 includes two photosensitive drums 111, that is, a first photosensitive drum and a second photosensitive drum.

[0084] Figure 12 is a table showing the number of prints on the first photosensitive drum, the cumulative single-area waste dot count formed on the first photosensitive drum when a printing operation corresponding to that number of prints is performed, and the cumulative total waste dot count of the entire area of ​​the first photosensitive drum. Figure 13 is a table showing the number of prints on the second photosensitive drum, the cumulative single-area waste dot count formed on the second photosensitive drum when a printing operation corresponding to that number of prints is performed, and the cumulative total waste dot count of the entire area of ​​the second photosensitive drum. The following description will be given with reference to the tables shown in FIG. 12 and FIG.

[0085] As shown in FIG. 12, on the first photosensitive drum, a total area waste dot count of 160.6 dots accumulates after one printing operation. In each area of ​​the first photosensitive drum, a single printing operation accumulates a single area waste dot count of 31 dots in the first and sixth areas, 28 dots in the second and third areas, and 14.6 dots in the fifth area.

[0086] As shown in FIG. 13, the second photosensitive drum accumulates a total area waste dot count of 45 dots after one printing operation. In each area of ​​the second photosensitive drum, a single printing operation accumulates 8 dot counts in the first area, 9 dot counts in the second and fifth areas, 5 dot counts in the third area, 10 dot counts in the fourth area, and 4 dot counts in the sixth area as single area waste dot counts.

[0087] For both the first photosensitive drum and the second photosensitive drum, the cumulative total waste dot count for all areas at the start of printing for the first to sixth printings does not exceed the total area deteriorated toner waste execution dot count, so the determination in step S21 of Figure 10 is NO, and the deteriorated toner waste process is not performed.

[0088] At the start of the seventh printing, in other words, when the sixth printing operation is performed, the total discard dot count of the first photosensitive drum in all areas, "963.6", exceeds the total area deteriorated toner discard execution dot count of "831". Therefore, the determination in step S21 in Fig. 10 is YES. As a result, the deteriorated toner discard execution check unit 174 executes the flow shown in Fig. 11, which is the process in step S22 in Fig. 10.

[0089] The deteriorated toner disposal execution check unit 174 first identifies "186" for the first and sixth areas as the maximum value among the cumulative single-area discard dot counts of all areas included in the first photosensitive drum being judged (S30 in FIG. 11).

[0090] Next, since the maximum value of the deteriorated toner discard execution check unit 174 exceeds the single area deteriorated toner discard execution dot count "138.5", step S31 in FIG. 11 becomes YES.

[0091] Therefore, the deteriorated toner disposal execution check unit 174 turns on the disposal execution flag of the area where the single area disposal dot count cumulative total exceeds the single area deteriorated toner disposal execution dot count (step S32 in FIG. 11). Here, since the cumulative total of the disposal dot counts of the first area, second area, third area, fourth area, and sixth area exceeds the single area deteriorated toner disposal execution dot count "138.5", the disposal execution flag of these areas is turned on.

[0092] This ends the flow of FIG. 11 in which the first photosensitive drum is the determination target. Then, through steps S23 and S24 in FIG. 10, the flow in FIG. 11 is executed with the second photosensitive drum as the determination target.

[0093] 11, the deteriorated toner discard execution check unit 174 identifies the maximum value among the accumulated single-area discard dot counts of all areas included in the second photosensitive drum, and stores the maximum value in the storage unit 150. In this example, the maximum value is "60" for the fourth area.

[0094] Next, since the maximum value does not exceed the single area deteriorated toner discard execution dot count "138.5", the determination in step S31 in FIG. 11 is NO.

[0095] Therefore, the deteriorated toner discard execution check unit 174 calculates a ratio value RT of the discard dot count (step S33 in FIG. 11). Here, the following formula (13) is obtained. RT = 60 ÷ 138.5 ≒ 0.43 (13)

[0096] Next, the deteriorated toner disposal execution check unit 174 turns on the disposal execution flag of the area in which the accumulated total of the disposal dot count is the maximum among all the areas included in the second photosensitive drum (step S34 in FIG. 11). In this case, since the fourth area has the maximum total, the disposal execution flag of the fourth area is turned on.

[0097] Next, the LED head light amount adjustment unit 176 sets a value obtained by multiplying the light amount value for illuminating the LED head 118 by the percentage value of the waste dot count as the light amount when disposing of the deteriorated toner on the second photosensitive drum (step S35 in FIG. 11). In other words, on the second photosensitive drum, the light amount for illuminating the LED head 118 when performing deteriorated toner disposal is 43%. Since the light amount of the LED head 118 is smaller, the amount of toner disposed in the deteriorated toner disposal operation is smaller than in normal deteriorated toner disposal.

[0098] With this, the flow of FIG. 11 is also completed for the second photosensitive drum, and in step S23 of FIG. 10, it is determined that the determination of all the photosensitive drums has been completed (YES in S23), and the process proceeds to step S25 of FIG.

[0099] In step S25 of FIG. 10, the deteriorated toner in the areas of the first photosensitive drum and the second photosensitive drum whose disposal execution flags are on is discarded. Here, on the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, and sixth areas is discarded. On the second photosensitive drum, the light amount of the LED head 118 is 43%, and deteriorated toner in the fourth area is discarded.

[0100] Then, the waste dot count update unit 173 subtracts the single area deteriorated toner waste execution dot count used for this deteriorated toner waste disposal from the single area waste dot count cumulative stored in the memory unit 150, and recalculates the all area waste dot count cumulative (step S26 in FIG. 10). For example, in the first photosensitive drum, the single area deteriorated toner discard execution dot count is subtracted from each of the single area waste dot count cumulative totals in the first area, the second area, the third area, the fourth area, and the sixth area, and the sum of the values ​​to be subtracted from the single area waste dot count cumulative totals in the first area, the second area, the third area, the fourth area, and the sixth area is subtracted from the entire area waste dot count cumulative total of the first photosensitive drum. In addition, in the second photosensitive drum, the single area waste dot count total of the fourth area is subtracted from the single area waste dot count total of the fourth area, i.e., the maximum value of the single area waste dot count total of the second photosensitive drum is subtracted.

[0101] Next, at the start of the 8th to 10th printing operations, the cumulative total discard dot count for all areas of the first and second photosensitive drums does not exceed the total area deteriorated toner discard execution dot count, so step S21 in Figure 10 becomes NO, and deteriorated toner discard processing is not performed.

[0102] At the start of the 11th printing operation, the total discard dot count for all areas of the first photosensitive drum exceeds the total deteriorated toner discard execution dot count, so the deteriorated toner discard execution determination in FIG. 11 is made again. The calculation process is the same as above and will not be described here, but here, for the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, fifth, and sixth areas is discarded. For the second photosensitive drum, the light amount of the LED head 118 is 64%, and deteriorated toner in the second and fifth areas is discarded.

[0103] Next, at the start of the 12th to 15th printing operations, the total area discard dot count for both the first photosensitive drum and the second photosensitive drum does not exceed the total area deteriorated toner discard execution dot count, so the result in step S21 of FIG. 10 is NO, and the deteriorated toner discard process is not performed.

[0104] At the start of the 16th printing operation, the total discard dot count of the first photosensitive drum in all areas exceeds the total deteriorated toner discard execution dot count, so the deteriorated toner discard execution determination in FIG. 11 is made again. The calculation process is the same as above and will not be described here, but here, for the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, and sixth areas is discarded. For the second photosensitive drum, the light amount of the LED head 118 is 86%, and deteriorated toner in the first area is discarded.

[0105] As described above, in the first embodiment, when the deteriorated toner disposal of a certain photosensitive drum is executed, the waste dot counts of all the photosensitive drums are checked. At that time, for the areas of the photosensitive drum where the maximum value of the single area waste dot count accumulation does not exceed the single area deteriorated toner disposal execution dot count, the light amount is reduced and the deteriorated toner is disposed of in the area where the single area waste dot count accumulation is the largest. Therefore, even for photosensitive drums where the total area discard dot count does not exceed the total area deteriorated toner discard execution dot count, deteriorated toner can be discarded in advance for areas where deteriorated toner is likely to accumulate. Therefore, the timing for discarding deteriorated toner for each photosensitive drum can be appropriate, and a drop in performance can be prevented.

[0106] Embodiment 2 As shown in FIG. 1, the configuration of the main parts of an image forming apparatus 200 according to the second embodiment is similar to that of the image forming apparatus 100 according to the first embodiment. As shown in FIG. 3, the image forming apparatus 200 according to the second embodiment includes a storage unit 250, a control unit 270, an input unit 181, a display unit 182, and an image forming main body 183. An input unit 181, a display unit 182, and an image forming main body 183 of the image forming apparatus 200 according to the second embodiment are similar to the input unit 181, the display unit 182, and the image forming main body 183 of the image forming apparatus 100 according to the first embodiment.

[0107] The storage unit 250 stores data and programs necessary for processing in the image forming apparatus 200 . FIG. 14 is a schematic diagram showing an example of programs and data stored in storage unit 250 in the second embodiment. The memory unit 250 stores a program, an all-area deteriorated toner discard slice value, an all-area deteriorated toner discard execution dot count, a single-area deteriorated toner discard slice value, a single-area deteriorated toner discard execution dot count, an all-area dot count, a drum count progress, an all-area discard threshold dot count, an all-area discard dot count, a total all-area discard dot count, a single-area dot count, a single-area discard threshold dot count, a single-area discard dot count, a total single-area discard dot count, a discard execution flag, a maximum value of the total single-area discard dot count, a percentage value of the discard dot count, a variable for area check destination, a maximum value of the total single-area remaining discard dot count, a minimum value of the maximum value of the total single-area remaining discard dot count, and a discard dot count for deteriorated toner discard execution.

[0108] The all-area deteriorated toner discard slice value, all-area deteriorated toner discard execution dot count, single-area deteriorated toner discard slice value, single-area deteriorated toner discard execution dot count, all-area dot count, drum count progress, all-area discard threshold dot count, all-area discard dot count, all-area discard dot count cumulative, single-area dot count, single-area discard threshold dot count, single-area discard dot count, single-area discard dot count cumulative, discard execution flag, maximum value of single-area discard dot count cumulative, and discard dot count percentage value stored in memory unit 250 in embodiment 2. The values ​​are the same as the all area deteriorated toner discard slice value, all area deteriorated toner discard execution dot count, single area deteriorated toner discard slice value, single area deteriorated toner discard execution dot count, all area dot count, drum count progress, all area discard threshold dot count, all area discard dot count, all area discard dot count cumulative, single area dot count, single area discard threshold dot count, single area discard dot count, single area discard dot count cumulative, discard execution flag, maximum value of single area discard dot count cumulative, and discard dot count percentage value stored in memory unit 150 of form 1.

[0109] In addition, it is desirable that the variable for area check destination, the maximum value of the cumulative remaining discard dot count in a single area, the minimum value of the maximum value of the cumulative remaining discard dot count in a single area, and the discard dot count for executing deteriorated toner disposal are also stored in a temporary memory unit that can temporarily store data, such as a RAM.

[0110] Returning to FIG. 3, the control unit 270 controls the processing in the image forming apparatus 200 . FIG. 15 is a block diagram showing a schematic configuration of control unit 270 in the second embodiment. The control unit 270 includes an image forming management unit 171, a waste dot count calculation unit 172, a waste dot count update unit 173, a deteriorated toner disposal execution check unit 274, a deteriorated toner disposal execution unit 275, an LED head light intensity adjustment unit 176, and a remaining waste dot count accumulation calculation unit 277.

[0111] Image formation management unit 171, discard dot count calculation unit 172, discard dot count update unit 173, and LED head light intensity adjustment unit 176 of control unit 270 in embodiment 2 are similar to image formation management unit 171, discard dot count calculation unit 172, discard dot count update unit 173, and LED head light intensity adjustment unit 176 of control unit 170 in embodiment 1.

[0112] If none of the multiple areas of the second image forming unit 110 satisfy the predetermined conditions described in embodiment 1, the deteriorated toner disposal execution check unit 274 determines whether there is one or more areas among the multiple areas of the second image forming unit 110 in which the total disposal amount in a single area exceeds the third threshold value.

[0113] Here, the deteriorated toner disposal execution check unit 274 specifies multiple maximum values ​​by repeating a process of selecting an area one by one from the multiple areas in turn in each of the multiple image forming units 110 except the first image forming unit 110 as a target area and subtracting the single-area total waste amount of the target area from the single-area total waste amount of each of the multiple areas. Then, the deteriorated toner disposal execution check unit 274 specifies the single-area total waste amount of the target area corresponding to the minimum value of the multiple maximum values ​​as a third threshold value.

[0114] If the deteriorated toner disposal execution check unit 274 determines that one or more areas as described above exist, the deteriorated toner disposal execution unit 275 controls the second LED head 118 and the second image forming unit 110 to form a disposal developer image in each of the one or more areas, thereby disposing of toner from the one or more areas. Here, the deteriorated toner disposal execution unit 275 discards the amount of toner corresponding to the third threshold from each of the one or more areas. Specifically, the deteriorated toner disposal execution unit 275 instructs the LED head light amount adjustment unit 176 to adjust the amount of light from the corresponding LED head 118, thereby causing the amount of toner corresponding to the third threshold to be discarded from each of the one or more areas.

[0115] FIG. 16 is a flowchart showing the deteriorated toner disposal execution determination process according to the second embodiment. It should be noted that among the steps included in the flowchart shown in FIG. 16, steps that perform processing similar to the processing of the steps included in the flowchart shown in FIG. 11 are given the same reference numerals as in FIG.

[0116] The processing from steps S30 to S32 in FIG. 16 is similar to the processing from steps S30 to S32 in FIG. However, in FIG. 16, in step S31, if the maximum value of the cumulative single-area discard dot count of the areas included in the photosensitive drum 111 being judged does not exceed the single-area deteriorated toner discard execution dot count (NO in S31), processing proceeds to step S40.

[0117] In step S40, the remaining discard dot count calculation unit 277 identifies a predetermined area from among all areas of the photosensitive drum 111 being judged as the area to be checked first, and sets a variable for area check destination to indicate the identified area.

[0118] Next, the remaining discard dot count calculation unit 277 uses the single-area discard dot count cumulative total of the area (also called the target area) indicated by the area check destination variable to calculate the remaining discard dot count cumulative total, which is the single-area discard dot count cumulative total that will remain in each area when the deteriorated toner disposal operation is performed for all areas, and identifies the maximum value (S41). The remaining discard dot count total is calculated by subtracting the single area discard dot count total of the area indicated by the area check destination variable from the single area discard dot count total of the area to be calculated. However, if the single area discard dot count total of the area to be calculated is smaller than the single area discard dot count total of the area indicated by the area check destination variable, the calculation of the remaining discard dot count total is skipped.

[0119] Next, the remaining discard dot count accumulating unit 277 judges whether or not all areas included in the photosensitive drum 111 being judged have been set as area check destination variables (S42). If all areas have not been set as area check destination variables (No in S42), in other words, if there are areas remaining that have not been set as area check destination variables, the process proceeds to step S43. On the other hand, if all areas have been set as area check destination variables (YES in S42), the process proceeds to step S44.

[0120] In step S43, the remaining discarded dot count accumulator 277 sets information indicating one area that has not been set as an area check destination variable as an area check destination variable, and the process returns to step S41.

[0121] Meanwhile, in step S44, the remaining discard dot count accumulation calculation unit 277 identifies the minimum value among the maximum values ​​of the remaining discard dot count accumulation identified for each area set as the area check destination variable. The remaining discard dot count accumulation calculation unit 277 also identifies the single area discard dot count of the area corresponding to the identified minimum value as the discard dot count for executing deteriorated toner discard, and stores the discard dot count for executing deteriorated toner discard in the storage unit 150. The discard dot count for executing deteriorated toner discard corresponds to a third threshold value.

[0122] Then, the deteriorated toner discard execution check unit 274 calculates a discard dot count ratio RT# by the following formula (14). RT# = (deteriorated toner disposal dot count) / (deteriorated toner disposal dot count for a single area) (14)

[0123] Next, the deteriorated toner disposal execution check unit 274 turns on the disposal execution flag for the area, among all areas included in the photosensitive drum 111 to be judged, where the cumulative single-area disposal dot count exceeds the disposal dot count for deteriorated toner disposal execution (S46).

[0124] Next, the LED head light amount adjustment unit 176 multiplies the light amount setting of the LED head 118 by the ratio value of the discard dot count to set the light amount when performing exposure (S47). For the areas in which the discard execution flag is turned on in step S46, exposure is performed with the set light amount when performing toner disposal in step S25 of FIG.

[0125] Next, the operations of the flowcharts shown in FIG. 10 and FIG. 16 in the second embodiment will be described using a specific example. Here, an example will be described in which the image forming apparatus 200 includes two photosensitive drums 111, that is, a first photosensitive drum and a second photosensitive drum. In addition, the table showing the number of prints on the first photosensitive drum, the cumulative single-area waste dot count formed on the first photosensitive drum when a printing operation corresponding to that number of prints is performed, and the cumulative total waste dot count of the entire area of ​​the first photosensitive drum is the same as the table shown in Figure 12.

[0126] Figure 17 is a table showing the number of times printing is performed on the second photosensitive drum in embodiment 2, the cumulative single-area waste dot count formed on the second photosensitive drum when a printing operation corresponding to that number of times is performed, and the cumulative total waste dot count of the entire area of ​​the second photosensitive drum.

[0127] As shown in FIG. 17, on the second photosensitive drum, as in the case of the first embodiment, the total area waste dot count accumulates to 45 dot counts after one printing operation. In each area of ​​the second photosensitive drum, a single printing operation results in a single area waste dot count of 8 dots in the first area, 9 dots in the second and fifth areas, 5 dots in the third area, 10 dots in the fourth area, and 4 dots in the sixth area. This is also the same as in the first embodiment.

[0128] For both the first photosensitive drum and the second photosensitive drum, the cumulative total waste dot count for all areas at the start of printing for the first to sixth printings does not exceed the total area deteriorated toner waste execution dot count, so the determination in step S21 of Figure 10 is NO, and the deteriorated toner waste process is not performed.

[0129] At the start of the seventh printing, in other words, when the sixth printing operation is performed, the total waste dot count of the first photosensitive drum in all areas, "963.6", exceeds the total area deteriorated toner waste execution dot count, "831". Therefore, the determination in step S21 in Fig. 10 is YES. The process performed here is the same as in the first embodiment, so a description thereof will be omitted.

[0130] When the flow in FIG. 16 in which the first photosensitive drum is the determination target is ended, the flow in FIG. 16 is executed in which the second photosensitive drum is the determination target via steps S23 and S24 in FIG.

[0131] 16, the deteriorated toner discard execution check unit 274 identifies the maximum value among the accumulated single-area discard dot counts of all areas included in the second photosensitive drum, and stores the maximum value in the storage unit 250. In this example, the maximum value is "60" for the fourth area.

[0132] Next, since the maximum value does not exceed the single area deteriorated toner discard execution dot count "138.5", the determination in step S31 in FIG. 16 is NO.

[0133] Then, the deteriorated toner disposal execution checking unit 274 sets the area to be checked first (step S41 in FIG. 16). Here, the deteriorated toner disposal execution checking unit 274 sets information indicating the first area to the area check destination variable.

[0134] Next, the deteriorated toner disposal execution check unit 274 uses the single-area discard dot count cumulative total of the area set in the area check destination variable to calculate, for each area, the single-area remaining discard dot count cumulative total, which is the remainder of the single-area discard dot count cumulative total when the deteriorated toner disposal operation is performed for all areas included in the target photosensitive drum 111. Then, the deteriorated toner disposal execution check unit 274 stores the maximum value among them in the storage unit 250.

[0135] For example, in the example shown in FIG. 17, the single area discard dot count total of the first area is "48", so when discarding degraded toner for this 48 dot count, the single area remaining discard dot count total of the first area becomes "0 (=48-48)". The single area remaining discard dot count total of the second area becomes "6 (=54-48)". The single area remaining discard dot count total of the third area is "30", which is not yet "48", so the calculation is skipped. The single area remaining discard dot count total of the fourth area becomes "12 (=60-48)". The single area remaining discard dot count total of the fifth area becomes "6 (=54-48)". The single area remaining discard dot count total of the sixth area is "24", which is not yet "48", so the calculation is skipped. From the above, the maximum cumulative value of the remaining discard dot count in a single area is "30".

[0136] Next, the deteriorated toner disposal execution check unit 274 judges whether or not all areas included in the photosensitive drum 111 to be judged have been checked (step S42 in FIG. 16). Here, since the area check destination variable is information indicating the first area, the result is NO.

[0137] Then, the deteriorated toner disposal execution check unit 274 sets information indicating the second area in the area check destination variable (step S43 in FIG. 16), and the process returns to step S41. As a result, the same process as for the first area is performed for the second area, and similar processes are performed for the third to sixth areas.

[0138] When the process for checking the sixth area is completed, the deteriorated toner discard execution check unit 274 identifies the minimum value among the maximum values ​​of the cumulative count of remaining discard dots in a single area (step S44 in FIG. 16). In this case, the maximum value of the single area remaining discard dot count cumulative value when the first area is checked is "30", the maximum value of the single area remaining discard dot count cumulative value when the second area is checked is "48", the maximum value of the single area remaining discard dot count cumulative value when the third area is checked is "30", the maximum value of the single area remaining discard dot count cumulative value when the fourth area is checked is "54", the maximum value of the single area remaining discard dot count cumulative value when the fifth area is checked is "48", and the maximum value of the single area remaining discard dot count cumulative value when the sixth area is checked is "36", so the minimum value is "30". Then, the deteriorated toner disposal execution check unit 274 sets "48", which is the cumulative single area disposal dot count of the first or third area being checked that results in the minimum value, as the disposal dot count for deteriorated toner disposal execution.

[0139] Next, the deteriorated toner discard execution check unit 274 calculates a ratio value RT# of the discard dot count (step S45 in FIG. 16). Here, the following formula (15) is obtained. RT#=48÷138.5≒0.34 (15)

[0140] Next, the deteriorated toner disposal execution check unit 274 turns on the disposal execution flag of the area where the single area disposal dot count cumulative total exceeds the deteriorated toner disposal execution disposal dot count (step S46 in FIG. 16). Here, the disposal execution flags of the first area, second area, fourth area, and fifth area are turned on.

[0141] Next, the LED head light amount adjustment unit 176 sets a value obtained by multiplying the light amount value for illuminating the LED head 118 by the percentage value of the waste dot count as the light amount when disposing of the deteriorated toner on the second photosensitive drum (step S47 in FIG. 16). In other words, on the second photosensitive drum, the light amount for illuminating the LED head 118 when performing deteriorated toner disposal is 34%. Since the light amount of the LED head 118 is smaller, the amount of toner disposed in the deteriorated toner disposal operation is smaller than in normal deteriorated toner disposal.

[0142] With this, the flow of FIG. 16 is also completed for the second photosensitive drum, and in step S23 of FIG. 10, it is determined that the determination of all the photosensitive drums has been completed (YES in S23), and the process proceeds to step S25 of FIG.

[0143] In step S25 of FIG. 10, the deteriorated toner in the areas of the first photosensitive drum and the second photosensitive drum where the disposal execution flag is on is discarded. Here, on the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, and sixth areas is discarded. On the second photosensitive drum, the light amount of the LED head 118 is 34%, and deteriorated toner in the first, second, fourth, and fifth areas is discarded.

[0144] Then, the waste dot count update unit 173 subtracts the single area deteriorated toner waste execution dot count used for this deteriorated toner waste disposal from the single area waste dot count cumulative stored in the memory unit 150, and recalculates the all area waste dot count cumulative (step S26 in FIG. 10).

[0145] Next, at the start of the 8th to 10th printing operations, the cumulative total discard dot count for all areas of the first and second photosensitive drums does not exceed the total area deteriorated toner discard execution dot count, so step S21 in Figure 10 becomes NO, and deteriorated toner discard processing is not performed.

[0146] At the start of the 11th printing operation, the total discard dot count for all areas of the first photosensitive drum exceeds the total deteriorated toner discard execution dot count, so the deteriorated toner discard execution determination in FIG. 11 is made again. The calculation process is the same as above and will not be described here, but here, for the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, fifth, and sixth areas is discarded. For the second photosensitive drum, the light amount of the LED head 118 is 23%, and deteriorated toner in the first, second, third, fourth, fifth, and sixth areas is discarded.

[0147] Next, at the start of the 12th to 15th printing operations, the total area discard dot count for both the first photosensitive drum and the second photosensitive drum does not exceed the total area deteriorated toner discard execution dot count, so the result in step S21 of FIG. 10 is NO, and the deteriorated toner discard process is not performed.

[0148] At the start of the 16th printing operation, the total discard dot count of the first photosensitive drum in all areas exceeds the total deteriorated toner discard execution dot count, so the deteriorated toner discard execution determination in FIG. 11 is made again. The calculation process is the same as above and will not be described here, but here, for the first photosensitive drum, the light amount of the LED head 118 is 100%, and deteriorated toner in the first, second, third, fourth, and sixth areas is discarded. For the second photosensitive drum, the light amount of the LED head 118 is 34%, and deteriorated toner in the first, second, third, fourth, and fifth areas is discarded.

[0149] In the first embodiment, if the single-area discard dot count cumulative total does not exceed the single-area deteriorated toner discard execution dot count, the light intensity of the LED head 118 for discarding the deteriorated toner is adjusted based on the single-area discard dot count cumulative total of the area with the highest single-area discard dot count cumulative total among the areas.

[0150] On the other hand, in the second embodiment, the cumulative waste dot count for each area is used to calculate the cumulative remaining waste dot count for a single area when degraded toner is discarded, and the values ​​are compared to adjust the amount of light from the LED head 118 when degraded toner is discarded, thereby making it possible to reduce the remaining cumulative waste dot count for a single area as much as possible after degraded toner is discarded. In this way, the number of times toner disposal is performed can be further reduced, and a drop in performance can be prevented.

[0151] In the first and second embodiments, an example in which the photosensitive drum 111 is divided into six areas has been described, but the first and second embodiments are not limited to such an example. For example, the photosensitive drum 111 may be divided into five or fewer areas, or seven or more areas.

[0152] In the first and second embodiments, the image forming unit 110 includes the drum waste toner collection container 116. Therefore, when the drum waste toner collection container 116 becomes full, it is necessary to replace the image forming unit 110, but the first and second embodiments are not limited to this example. For example, the drum waste toner collection container 116 may be included inside the toner cartridge 117. In such a case, when the drum waste toner collection container 116 becomes full, it is necessary to replace the toner cartridge 117.

[0153] In the first and second embodiments, the electrostatic latent image is written on the photosensitive drum 111 by the LED head 118, but the first and second embodiments are not limited to such examples. For example, the electrostatic latent image may be formed by other methods such as a laser head.

[0154] In the first and second embodiments, when the single area waste dot count total does not exceed the single area deteriorated toner waste execution count, the amount of light during exposure is reduced to discard the deteriorated toner, but the first and second embodiments are not limited to this example. For example, when the single area waste dot count total exceeds the single area deteriorated toner waste execution count, the amount of light may be increased to discard the deteriorated toner.

[0155] For example, in the case where there are four photosensitive drums to be checked for the disposal of deteriorated toner, in the conventional technology, the duty of each area of ​​each photosensitive drum is checked at the timing of the check, and the deteriorated toner is disposed of in that area only if it is below the threshold. For example, if the duty of an area of ​​the first photosensitive drum is below the threshold and none of the areas of the second photosensitive drum are slightly below the threshold, the deteriorated toner is disposed of in the area of ​​the first photosensitive drum, but the deteriorated toner is not disposed of in the second photosensitive drum.

[0156] However, if the second photosensitive drum is used in the same way, the duty falls below the threshold at an early stage, but the duty check of the second photosensitive drum is not performed until the next check timing, which causes a problem that printing continues on the second photosensitive drum with degraded toner accumulated until the next check timing.

[0157] In contrast, in the first or second embodiment, the duty of each area is checked even for photosensitive drums where the duty of none of the areas is below the threshold at the timing of checking the duty of each area. Then, even in areas where the duty is not below the threshold, if deteriorated toner has accumulated, the amount of light exposure is adjusted to discard the deteriorated toner. This makes it possible to prevent the deterioration toner from remaining.

[0158] In addition, discarding deteriorated toner also takes time, so by discarding deteriorated toner on one photosensitive drum at the same time as discarding deteriorated toner on another photosensitive drum, it is possible to reduce the number of times that deteriorated toner disposal control is performed at a different timing, and it is possible to prevent a drop in performance. [Explanation of symbols]

[0159] 100,200 image forming apparatus, 110 image forming unit, 111 photosensitive drum, 112 charging roller, 113 supply roller, 114 developing roller, 115 cleaning blade, 116 drum waste toner collection container, 120 transfer unit, 121 transfer roller, 122 transfer belt, 123 belt cleaning blade, 124 belt waste toner collection container, 130 fixing unit, 150 memory unit, 170 control unit, 171 image formation management unit, 172 waste dot count calculation unit, 173 waste dot count update unit, 174 deteriorated toner disposal execution check unit, 175 deteriorated toner disposal execution unit, 176 LED head light amount adjustment unit, 181 input unit, 182 display unit, 183 image forming main body.

Claims

1. a plurality of image forming units each including an image carrier, a charging unit for uniformly charging the image carrier, and a developing unit for forming a developer image by attaching a developer to an electrostatic latent image formed on the image carrier; a plurality of exposure units for forming the electrostatic latent image by exposing the image carrier of each of the plurality of image forming units; a transfer unit that transfers the developer images formed by the plurality of image forming units onto a medium; a fixing section for fixing the developer image to the medium; a waste amount calculation unit that calculates, for each of the plurality of image forming units, a waste amount that is an amount of the developer to be discarded from each of the plurality of image forming units, each time an image forming operation for forming an image on the medium is performed using the plurality of image forming units, the plurality of exposure units, the transfer unit, and the fixing unit; a waste amount accumulating unit for calculating a total waste amount, which is an accumulation of the waste amounts, in each of the plurality of image forming units; a discard execution determination unit that determines whether the total discard amount of a first image forming unit included in the plurality of image forming units exceeds a first threshold value; a disposal execution unit that, when it is determined that the total disposal amount of the first image forming unit exceeds the first threshold value, controls a first exposure unit that exposes the first image forming unit and the first image forming unit among the plurality of exposure units to form a developer image for disposal, thereby discarding the developer from the first image forming unit, when determining that the total discard amount of the first image forming unit exceeds the first threshold, the discard execution determination unit determines whether or not a second image forming unit included in the plurality of image forming units excluding the first image forming unit satisfies a predetermined condition; When it is determined that the second image forming unit satisfies the predetermined condition, the disposal execution unit controls a second exposure unit that exposes the second image forming unit among the plurality of exposure units and the second image forming unit to form a developer image for disposal, thereby disposing of the developer from the second image forming unit. An image forming apparatus comprising:

2. the waste amount calculation unit divides a surface of the image carrier into a plurality of areas in a main scanning direction, and further calculates, for each of the plurality of areas, a single-area waste amount, which is an amount of the developer to be discarded from each of the plurality of areas, every time the image forming operation is performed; the waste amount accumulating unit further calculates a single-area total waste amount, which is an accumulation of the single-area waste amounts, in each of the plurality of areas; the predetermined condition is that the single area total discard amount exceeds a second threshold; When it is determined that the single area discard amount of one area included in the plurality of areas of the second image forming unit exceeds the second threshold value, the discard execution unit discards the developer from the one area by forming a discard developer image in the one area.

2. The image forming apparatus according to claim 1,

3. When none of the plurality of areas of the second image forming unit satisfies the predetermined condition, the discard execution determination unit specifies one or more areas among the plurality of areas of the second image forming unit in which the single-area total discard amount is a maximum value, The disposal execution unit controls the second exposure unit and the second image forming unit to form a developer image for disposal in each of the one or more areas, thereby disposing of the developer from the one or more areas.

3. The image forming apparatus according to claim 2, wherein

4. The discard execution unit discards the amount of the developer corresponding to the maximum value from each of the one or more areas.

4. The image forming apparatus according to claim 3,

5. The discard execution unit adjusts an amount of light from the second exposure unit to discard the amount of the developer corresponding to the maximum value from each of the one or more areas.

5. The image forming apparatus according to claim 4,

6. When none of the plurality of areas of the second image forming unit satisfies the predetermined condition, the discard execution determination unit determines whether or not there is one or more areas among the plurality of areas of the second image forming unit in which the single-area total discard amount exceeds a third threshold value; When it is determined that the one or more areas are present, the disposal execution unit controls the second exposure unit and the second image forming unit to form a developer image for disposal in each of the one or more areas, thereby disposing of the developer from the one or more areas.

3. The image forming apparatus according to claim 2, wherein

7. the discard execution determination unit, in each of the plurality of image forming units excluding the first image forming unit, sets an area selected one by one from the plurality of areas in order as a target area, and repeats a process of determining a maximum value obtained by subtracting the single-area total discard amount of the target area from the single-area total discard amount of each of the plurality of areas, thereby determining a plurality of maximum values, and sets the single-area total discard amount of the target area corresponding to the minimum value of the plurality of maximum values ​​as the third threshold value.

7. The image forming apparatus according to claim 6,

8. The discard execution unit discards the amount of the developer corresponding to the third threshold value from each of the one or more areas.

8. The image forming apparatus according to claim 7,

9. The discard execution unit discards the amount of the developer corresponding to the third threshold value from each of the one or more areas by adjusting an amount of light from the exposure unit.

9. The image forming apparatus according to claim 8,

Images