Image forming apparatus

Abstract

To provide an image forming apparatus that can appropriately perform image adjustment in accordance with a change in density caused by various conditions to stabilize image quality.SOLUTION: An image forming apparatus has: an image forming unit that forms developer images on image carriers; a reading unit that reads the density of the developer images for adjustment; an image adjustment result storage unit that stores a result of reading the developer images for adjustment; a deteriorated developer amount storage unit that stores the amount of accumulation of deteriorated developer; and an image adjustment control unit that performs predetermined image adjustment on the basis of a first image adjustment result in a state in which the amount of accumulation of deteriorated developer is equal to or more than a predetermined value and a second image adjustment result in a state in which the amount of accumulation of deteriorated developer is less than the predetermined value, which are stores in the image adjustment result storage unit, and the amount of accumulation of deteriorated developer stored in the deteriorated developer amount storage unit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] In the past, when image forming devices using continuous paper detected deterioration of developer (toner) during image formation, they would discharge the deteriorated developer or replenish with new developer to maintain the quality of the image formation. However, while performing these operations stabilized the image quality, it required temporarily halting image formation (printing).

[0003] Patent document 1 discloses a technology for performing image adjustment (density correction) by adjusting the amount of light from the exposure head according to the density of images printed so far during continuous printing, in order to stabilize image quality without discharging degraded toner. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-158922 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in conventional methods, the light intensity is adjusted based on a preset value rather than in response to actual density changes, making it unclear whether the light intensity is being properly corrected for density changes that vary depending on various conditions, such as ambient temperature, humidity, and the lifespan of the drum.

[0006] Therefore, there is a demand for an image forming apparatus that can appropriately adjust images to accommodate density changes that vary depending on various conditions, thereby stabilizing image quality. [Means for solving the problem]

[0007] The image forming apparatus of the present disclosure is characterized by having (1) an image forming unit that forms a developer image on an image carrier; (2) a reading unit that reads the density of the developer image for adjustment; (3) an image adjustment result memory unit that stores the reading result of the developer image for adjustment; (4) a deteriorated developer amount memory unit that stores the accumulated amount of deteriorated developer; and (5) an image adjustment control unit that performs a predetermined image adjustment based on a first image adjustment result stored in the image adjustment result memory unit when the accumulated amount of deteriorated developer is equal to or greater than a predetermined value, a second image adjustment result stored in the image adjustment result memory unit when the accumulated amount of deteriorated developer is less than a predetermined value, and the accumulated amount of deteriorated developer stored in the deteriorated developer amount memory unit. [Effects of the Invention]

[0008] According to the present disclosure, image adjustment can be performed appropriately to deal with density changes that vary depending on various conditions, thereby stabilizing image quality. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 2 is a block diagram showing the configuration of a control system of the printer according to the embodiment. [Figure 2] 1 is a diagram illustrating an outline of the overall configuration of a printer according to an embodiment. [Figure 3] FIG. 2 is a diagram illustrating the internal configuration of an image forming unit according to the embodiment. [Figure 4] 4 is a flowchart showing the printing operation (including image adjustment and deteriorated toner disposal operations) of the printer according to the embodiment. [Figure 5] 10 is a graph showing an example of calculating a light amount correction amount from the deteriorated toner accumulation amount stored in a deteriorated toner accumulation amount storage unit according to the embodiment; DETAILED DESCRIPTION OF THE INVENTION

[0010] (A) Main embodiment An embodiment of an image forming apparatus according to the present disclosure will be described in detail below with reference to the drawings. In the following, an example in which the image forming apparatus according to the present disclosure is applied to a printer will be described.

[0011] (A-1) Configuration of the embodiment FIG. 2 is a diagram showing an outline of the overall configuration of the printer according to the embodiment.

[0012] In Figure 2, printer 1 is a printer that performs electrophotographic printing on continuous paper P pulled out from a roll of paper 101, and has a printing unit 20 that forms an image on the continuous paper P and a feeder unit 10 that supplies the continuous paper P to this printing unit 20.

[0013] <Feeder unit> The feeder unit 10 is attached to the lower front surface of the printing unit 20 and includes a roll of paper 101 , a feeder motor 102 , a feeder transport roller 103 , a tension bar 104 , and a paper feed sensor 105 .

[0014] Within the feeder unit 10, a transport path R1 that connects the feeder unit 10 and the printing unit 20 is provided.

[0015] The roll paper 101 is provided at the front end of the feeder unit 10 and is rotatably held as a rolled medium.

[0016] The feeder motor 102 is a driving device for operating the feeder transport rollers 103 .

[0017] The feeder transport roller 103 transports the continuous paper P pulled out from the roll paper 101 to the printing unit 20 along the transport path R1.

[0018] The tension bar 104 is configured to move freely with a constant tension in order to keep the tension of the continuous paper P pulled out from the roll paper 101 constant.

[0019] The paper feed sensor 105 detects the presence or absence of continuous paper P being fed to the printing unit 20, and any abnormalities in conveyance.

[0020] <Printing unit> The printing unit 20 has an IN1 sensor 111, an IN2 sensor 112, an IN3 sensor 113, a transport motor 114, a transport roller group 115, a fixing unit 150, a pre-fixing slack sensor 151, a fixing motor 154, a fixing discharge sensor 155, a discharge sensor 156, a discharge roller 157, and an image forming unit 30.

[0021] Within the printing unit 20, a transport path R2 is provided, extending from the lower front surface to the lower rear surface. The front end of this transport path R2 is connected to the transport path R1 of the feeder unit 10, and the rear end is connected to a paper discharge port 160 provided on the rear surface of the printing unit 20. Within the printing unit 20, along this transport path R2, an IN1 sensor 111, an IN2 sensor 112, an IN3 sensor 113, an image forming unit 30, a pre-fixing slack sensor 151, a fixing unit 150, a fixing discharge sensor 155, and a discharge sensor 156 are provided in this order from upstream in the paper transport direction. Furthermore, within the printing unit 20, a transport roller group 115 and a discharge roller 157 are provided along this transport path R2.

[0022] The IN1 sensor 111, the IN2 sensor 112, and the IN3 sensor 113 detect the presence or absence of continuous paper P passing through the transport path R2, transport abnormalities, etc. The number and locations of the sensors to be placed inside the printer 1 are not particularly limited.

[0023] The transport motor 114 is a drive device for operating the transport roller group 115 .

[0024] The transport roller group 115 transports the continuous paper P supplied from the feeder unit 10 to the image forming unit 30 and the fixing unit 150 along the transport path R2.

[0025] The image forming unit 30 includes image forming sections 200 (200Y, 200M, 200C, 200K, and 200W), an intermediate transfer belt 130 serving as an intermediate transfer member, and a secondary transfer unit 140.

[0026] The image forming unit 30 transfers a developer image (hereinafter also referred to as a "toner image") developed with toner of each color onto the surface of the continuous paper P being transported along the transport path R2, thereby forming an image on the continuous paper P. In this embodiment, the image forming unit 30 employs a secondary transfer method in which the toner image formed on each image forming section 200 is primarily transferred onto the intermediate transfer belt 130, and then secondarily transferred from the intermediate transfer belt 130 onto the continuous paper P.

[0027] The image forming unit 30 has image forming sections 200 (200Y, 200M, 200C, 200K, 200W) corresponding to the respective colors of yellow (Y), magenta (M), cyan (C), black (K), and white (W). Each image forming section 200 stacks toner images on the intermediate transfer belt 130 without misalignment with one another.

[0028] The intermediate transfer belt 130 is supported by belt support rollers 131 to 133 and a backup roller 135 so as to be rotatable in the direction of the arrow Y. The intermediate transfer belt 130 is rotated by the drive of a belt motor 136 and conveys the toner image to a secondary transfer unit 140.

[0029] The secondary transfer unit 140 is disposed below the backup roller 135 and includes a secondary transfer roller 141 .

[0030] The secondary transfer roller 141 can come into contact with and separate from the backup roller 135 across the intermediate transfer belt 130. When the toner image on the intermediate transfer belt 130 passes through the backup roller 135, a secondary transfer bias is applied to the secondary transfer roller 141 from a high-voltage supply unit (not shown), so that the toner image is transferred to the continuous paper P.

[0031] A density sensor 137 as a reading unit detects the density of a patch image formed in the same procedure as the toner image on the intermediate transfer belt 130 during the image adjustment operation.

[0032] A belt cleaning roller 134 removes patch images that have not been transferred from the intermediate transfer belt 130. The patch images (as well as deteriorated toner as waste toner) are collected in a waste toner collector (not shown).

[0033] The pre-fixing slack sensor 151 detects the presence or absence of continuous paper P onto which a toner image has been transferred, conveyance abnormalities, and the like.

[0034] The fixing unit 150 has a heating belt 152 that heats the toner image, and a fixing backup roller 153 that clamps and presses the continuous paper P together with the heating belt 152. The heating belt 152 is rotated by a fixing motor 154 to fix the toner image while transporting the continuous paper P.

[0035] After the continuous paper P is fixed by the fixing unit 150, it is transported to an ejection roller 157 which is driven to rotate by a fixing motor 154, passes through a fixing ejection sensor 155 and an ejection sensor 156, and is ejected from the printer 1 through a paper ejection port 160.

[0036] <Internal configuration of the image forming unit> FIG. 3 is a diagram showing the internal configuration of the image forming unit according to the embodiment.

[0037] The image forming unit 200 has a toner chamber 201, a supply roller 202, a developing roller 203, a layer regulating blade 204, a photosensitive drum 205 as an image carrier, a charging roller 206, an exposure head 207 as an exposure unit, and a primary transfer roller 208.

[0038] The toner chambers 201 contain toner of the corresponding color (yellow, magenta, cyan, black, white).

[0039] The supply roller 202 has a function of supplying the toner in the toner chamber 201 to the developing roller 203 .

[0040] The developing roller 203 adheres toner to a latent image pattern (electrostatic latent image) formed on the photosensitive drum 205 to form a developer image.

[0041] The layer regulating blade 204 regulates the amount of toner adhering to the developing roller 203 .

[0042] Photoconductor drum 205 is a cylindrical member that carries an electrostatic latent image on its surface and is constructed using a photoconductor. When various toners are supplied to photoconductor drum 205, an image (toner image) corresponding to the electrostatic latent image is formed (developed).

[0043] The charging roller 206 is arranged around the photosensitive drum 205 and serves to uniformly charge the surface of the photosensitive drum 205 .

[0044] The exposure head 207 selectively exposes the uniformly charged surface of the photosensitive drum 205 to light to form an electrostatic latent image. The exposure head 207 is composed of, for example, LED elements, LED driving elements, and a lens array, and is positioned so that the light emitted from the LED elements forms an image on the surface of the photosensitive drum 205.

[0045] The primary transfer roller 208 transfers the toner image on the photosensitive drum 205 onto the intermediate transfer belt 130 .

[0046] <Control system configuration> Next, we will explain the configuration of the control system of the printer 1. Figure 1 is a block diagram showing the configuration of the control system of the printer according to this embodiment.

[0047] 1, the printer 1 has a control unit 300 that controls the above-mentioned motors (such as the feeder motor 102), sensors (such as the density sensor 137), and image forming units 200. The control unit 300 reads out various programs stored in a storage unit (not shown) into a memory (not shown) and executes them, thereby operating as a functional unit according to the various programs.

[0048] The control unit 300 includes a main control unit 301, an I / F unit 310, a command decode control unit 311, a sensor control unit 320, a motor control unit 321, a secondary transfer roller control unit 322, an image formation control unit 323, an image adjustment control unit 324, an image adjustment result memory unit 325, a deteriorated toner accumulation amount memory unit 326 as a deteriorated developer amount memory unit, and a deteriorated toner disposal control unit 327.

[0049] The I / F unit 310 receives print instructions and other operation instruction commands from a higher-level host (not shown), decodes the commands via a command decode control unit 311, and notifies the main control unit 301 of the commands one by one.

[0050] The main control unit 301 controls the main functions of the printer 1 in an integrated manner, and issues control instructions and acquires status to the sensor control unit 320, motor control unit 321, secondary transfer roller control unit 322, image formation control unit 323, image adjustment control unit 324, image adjustment result memory unit 325, deteriorated toner accumulation amount memory unit 326, and deteriorated toner disposal control unit 327 in response to request commands.

[0051] The sensor control unit 320 reads the sensor status of the paper feed sensor 105, the IN1 sensor 111, the IN2 sensor 112, the IN3 sensor 113, the fixing discharge sensor 155, and the discharge sensor 156 to detect the presence or absence of the continuous paper P, and obtains the slack state of the continuous paper P from the pre-fixing slack sensor 151.

[0052] The motor control unit 321 controls the rotational driving of the feeder motor 102, the transport motor 114, the belt motor 136, and the fixing motor 154, and transports the continuous paper P and the toner image.

[0053] The secondary transfer roller control unit 322 manages the contact and separation states between the secondary transfer roller 141 and the intermediate transfer belt 130, and controls the movement mechanism of the secondary transfer unit 140 to perform the contact operation and separation operation of the secondary transfer roller 141.

[0054] The image formation control unit 323 controls the image forming units 200Y, 200M, 200C, 200K, and 200W in accordance with an image formation request from the main control unit 301 to form a toner image.

[0055] When an image adjustment command is received from the main control unit 301, the image adjustment control unit 324 reads the toner image on the intermediate transfer belt 130 with the density sensor 137, performs image adjustment based on the toner image reading result, and adjusts the voltage applied to the developing roller 203 and the light intensity of the exposure head 207. Details of image adjustment will be described in the section on operation.

[0056] The image adjustment result storage unit 325 is a storage unit that stores the results of the image adjustment performed by the image adjustment control unit 324 .

[0057] The deteriorated toner accumulation amount storage unit 326 is a storage unit that stores the deteriorated toner accumulation amount Wto, which indicates the accumulated amount of deteriorated toner accumulated in the toner chamber 201.

[0058] The deteriorated toner disposal control unit 327 determines whether or not to perform the deteriorated toner disposal operation based on the deteriorated toner accumulation amount Wto stored in the deteriorated toner accumulation amount storage unit 326 and the deteriorated toner disposal execution threshold Wth, and then performs the deteriorated toner disposal operation. Details of the deteriorated toner disposal operation will be described in the operation section.

[0059] (A-2) Operation of the embodiment Next, the operation of the printer 1 according to the embodiment having the above configuration will be described. First, the image adjustment operation and the deteriorated toner disposal operation will be described, and then the flow of the printing operation of the printer 1 incorporating these operations will be described.

[0060] (A-2-1) Image adjustment operation First, the operation of image adjustment will be described with reference to the above-mentioned FIGS.

[0061] The image formation control unit 323 controls the image forming units 200 (200Y, 200M, 200C, 200K, and 200W) to form patch images for image adjustment on the intermediate transfer belt 130.

[0062] When the image adjustment patch on the intermediate transfer belt 130 reaches the reading position of the density sensor 137 due to the rotational drive of the belt motor 136, the density sensor 137 reads the patch image and notifies the image adjustment control unit 324 of the reading result.

[0063] The image adjustment control unit 324 performs image adjustment based on the density difference between the target density (set density) of the patch image and the read density.

[0064] In this embodiment, as an example of an image adjustment method, the light intensity of exposure head 207 is adjusted. By adjusting the exposure amount of exposure head 207, the potential of the development portion on photosensitive drum 205 is adjusted. Even if the potential of the toner changes, the toner image developed on photosensitive drum 205 is adjusted to an appropriate density by adjusting the potential of the exposed portion.

[0065] (A-2-2) Deteriorated toner disposal operation Next, the deteriorated toner discarding operation will be explained with reference to the above-mentioned Figures 1 to 3. First, the reason for performing the deteriorated toner discarding operation will be explained.

[0066] During a printing operation, the lower the image density of the print data, the greater the amount of toner that remains on developing roller 203 without adhering to photosensitive drum 205. The toner remaining on developing roller 203 is scraped off by supply roller 202, which rotates in the opposite direction, and collected into toner chamber 201. During the next printing operation, the collected toner is again supplied from supply roller 202 to developing roller 203, where it is charged and thinned by friction with layer regulating blade 204.

[0067] If printing with low image density continues, the above-mentioned process is repeated, causing the external additives in the toner to peel off and deteriorate. This changes the toner's charging characteristics, resulting in a decrease in image quality. For example, deteriorated toner has an increased charge and takes on a higher-than-normal potential. This causes excessive toner to adhere to the photosensitive drum 205, resulting in a print density that is darker than desired, resulting in a decrease in print quality.

[0068] Therefore, in order to prevent a decrease in print quality, when a certain amount of deteriorated toner accumulates, an operation is performed to discard the deteriorated toner.

[0069] The deteriorated toner accumulation amount storage unit 326 stores the deteriorated toner accumulation amount Wto accumulated in the toner chamber 201.

[0070] The amount of deteriorated toner accumulated Wto is calculated by, for example, using the amount of deteriorated toner accumulated when 10 sheets of low-density images with an image density of 1% are printed continuously on A4-sized paper as one unit, and is incremented by 1. The amount of deteriorated toner accumulated Wto is also decremented when high-density images are printed continuously or when toner is discarded through the deteriorated toner disposal operation. For example, the amount of deteriorated toner accumulated Wto is decremented by 1 when 10 sheets of high-density images with an image density of 10% are printed continuously on A4-sized paper.

[0071] When the amount of accumulated deteriorated toner Wto exceeds the deteriorated toner disposal threshold Wth, the deteriorated toner disposal control unit 327 performs an operation to discard the deteriorated toner near the supply roller 202. In the deteriorated toner disposal operation, the deteriorated toner is supplied from the supply roller 202 to the development roller 203. A pattern image for discarding the deteriorated toner is formed on the photosensitive drum 205 by the exposure head 207. The deteriorated toner on the development roller 203 adheres to the photosensitive drum 205 and is transferred onto the intermediate transfer belt 130 by the primary transfer roller 208.

[0072] The deteriorated toner transferred onto the intermediate transfer belt 130 is scraped off by a belt cleaning roller 134 and collected in a waste toner collector (not shown).

[0073] (A-2-3) Printer 1 printing operation FIG. 4 is a flowchart showing the printing operation (including image adjustment and deteriorated toner disposal operations) of the printer according to the embodiment.

[0074] <s101> The main control unit 301 determines whether or not a print instruction has been issued from a higher-level host (not shown). If a print instruction has been issued, the main control unit 301 proceeds to step S108. If a print instruction has not been issued, the main control unit 301 proceeds to step S102.

[0075] <s102> If it is determined in step S101 above that a print instruction does not exist, the image adjustment control unit 324 determines whether the image adjustment conditions are met. The image adjustment conditions are not particularly limited. For example, the image adjustment control unit 324 determines that the image adjustment conditions are met if 400 or more pages have been printed since the previous image adjustment or if six or more hours have passed since the previous image adjustment. If the image adjustment conditions are met, the image adjustment control unit 324 proceeds to step S103. If the image adjustment conditions are not met, the image adjustment control unit 324 returns to step S101 above.

[0076] <s103> The image adjustment control unit 324 erases the image adjustment result stored in the image adjustment result storage unit 325 (the previous image adjustment result).

[0077] <s104> The image adjustment control unit 324 performs the first image adjustment operation (the above-mentioned (A-2-1)), and stores the image adjustment result (first time) in the image adjustment result storage unit 325.

[0078] <s105> The deteriorated toner disposal control unit 327 determines whether or not a certain amount of deteriorated toner has accumulated in the toner chamber 201. For example, the deteriorated toner disposal control unit 327 determines that deteriorated toner has accumulated when the deteriorated toner accumulation amount Wto is equal to or greater than the deteriorated toner disposal execution threshold Wth.

[0079] If deteriorated toner has accumulated, the deteriorated toner discard control unit 327 proceeds to step S106, whereas if deteriorated toner has not accumulated, the process returns to step S101.

[0080] <s106> The deteriorated toner disposal control unit 327 performs the deteriorated toner disposal operation ((A-2-2) above).

[0081] <s107> The image adjustment control unit 324 performs the image adjustment operation again, and stores the image adjustment result (second time) in the image adjustment result storage unit 325.

[0082] In this flow, the first image adjustment result when step S104 is performed and it is determined in step S105 that there is accumulated deteriorated toner is the image adjustment result of a state in which a predetermined amount or more of deteriorated toner has accumulated.The second image adjustment result after steps S105 and S106 are performed is the image adjustment result of a state in which there is almost no deteriorated toner (in other words, a state in which there is accumulated deteriorated toner less than a predetermined amount).

[0083] <s108> If it is determined in step S101 that there is no print instruction, the main control unit 301 controls each unit to start the print operation.

[0084] <s109> During printing operation, the image adjustment control unit 324 refers to the deteriorated toner accumulation amount memory unit 326 to determine whether there has been a change in the deteriorated toner accumulation amount Wto, and whether the image adjustment result memory unit 325 stores both the results of the first image adjustment performed in the above-mentioned step S104 and the results of the second image adjustment performed in the above-mentioned step S107.

[0085] The criteria for determining that the amount of deteriorated toner accumulated Wto has changed are not particularly limited, but for example, if the amount of deteriorated toner accumulated Wto changes by even one unit, it may be determined that the amount of deteriorated toner accumulated Wto has changed, or if the amount of deteriorated toner accumulated Wto changes by a certain range (from several units to several tens of units), it may be determined that the amount of deteriorated toner accumulated Wto has changed.

[0086] If there is a change in the amount of deteriorated toner accumulated Wto and both the first and second image adjustment results exist, the image adjustment control unit 324 proceeds to step S110, and if there is no change in the amount of deteriorated toner accumulated Wto (or if there are neither the first nor second image adjustment results), the image adjustment control unit 324 proceeds to step S112.

[0087] <s110> The image adjustment control unit 324 calculates the light amount correction amount based on the result of the first image adjustment performed in step S104 described above, the result of the second image adjustment performed in step S107 described above, and the deteriorated toner accumulation amount Wto stored in the deteriorated toner accumulation amount storage unit 326. The method for calculating the light amount correction amount will be described in detail later.

[0088] <s111> The image formation control unit 323 adjusts the exposure amount of the exposure head 207 in accordance with instructions from the image adjustment control unit 324 .

[0089] <s112> The main control unit 301 determines whether print data remains. If print data remains, the main control unit 301 continues printing and returns to step S109. On the other hand, if no print data remains, the main control unit 301 ends the printing operation and returns to START (the start of the flow in FIG. 4).

[0090] (A-2-4) Calculation method for light intensity correction amount (Details of step S110) The method for calculating the light quantity correction amount performed in step S110 will now be described. Fig. 5 is a graph showing an example of calculating the light quantity correction amount from the deteriorated toner accumulation amount Wto stored in the deteriorated toner accumulation amount storage unit 326 according to the embodiment.

[0091] Fig. 5(A) shows the image adjustment results stored in image adjustment result storage unit 325. As shown in Fig. 5(A), the first image adjustment result is a light intensity correction amount of 15% when the amount of accumulated deteriorated toner is 20 units, and the second image adjustment result is a light intensity correction amount of 23% when the amount of accumulated deteriorated toner is 0 units.

[0092] The image adjustment control unit 324 linearly interpolates these two results. Outside the range of the two points, the light intensity correction amount corresponding to the deteriorated toner accumulation amount Wto is calculated from the slope, and the light intensity correction amount can be calculated using the following equation (1). Light intensity correction amount [%] = -0.4% * Degraded toner accumulation amount Wto [unit] + 23% …(1)

[0093] FIG. 5B shows the relationship between the amount of accumulated deteriorated toner Wto and the amount of light amount correction based on the above formula (1).

[0094] As printing at low image density continues and the amount of deteriorated toner accumulated Wto increases, the amount of light intensity correction decreases. This is because, as printing at low image density continues, the external additives in the toner peel off, increasing the amount of charge on the toner, making it easier for the toner to adhere to the photosensitive drum 205 and resulting in a higher print density. Therefore, by reducing the amount of exposure of the head, the potential of the development area is brought closer to the potential of the toner, making it more difficult for the toner to move onto the photosensitive drum 205.

[0095] For example, according to the above formula (1), when the amount of accumulated deteriorated toner Wto is 30 units, the amount of light amount correction can be calculated as +11%.

[0096] Similar correction can also be applied when the amount of accumulated deteriorated toner becomes negative due to continued high-density printing. When high-density printing continues, the amount of charge on the toner decreases, making it difficult for the toner to adhere to the photosensitive drum 205. Therefore, by increasing the amount of light, the potential difference between the developed area and the toner increases.

[0097] For example, according to the above formula (1), when the amount of accumulated deteriorated toner Wto is −20 units, the amount of light amount correction is +31%.

[0098] In addition, upper and lower limit values ​​are set for the amount of light intensity correction to prevent excessive correction. The upper and lower limit values ​​are not particularly limited, but for example, the upper limit value of the amount of light intensity correction is set to +40% and the lower limit value is set to -40%.

[0099] In this way, it is possible to appropriately apply the amount of light quantity correction according to the current amount of deteriorated toner accumulation Wto from the two image adjustment results stored in the image adjustment result storage unit 325 .

[0100] (A-3) Effects of the embodiment As described above, the present embodiment provides the following advantages.

[0101] The printer 1 can stabilize image quality without discarding the deteriorated toner (in other words, without interrupting the printing operation) by correcting the light intensity of the exposure head 207 according to the amount of deteriorated toner accumulated Wto while printing the continuous paper P.

[0102] In addition, the amount of light intensity correction is calculated based on the current amount of deteriorated toner accumulated Wto from the image adjustment results (density correction results) for the most recent state in which deteriorated toner was accumulated (first time) and the state in which there was no deteriorated toner (second time), so image adjustment can be performed appropriately.

[0103] (B) Other embodiments Although various modified embodiments have been mentioned in the above-described embodiments, the following modified embodiments can also be applied.

[0104] (B-1) In the above-described embodiment, a color printer using five colors was used as an example of the image forming apparatus, but the number of colors used for printing is not particularly limited, and a monochrome printer may also be used, for example.

[0105] (B-2) In the above-described embodiment, an image forming apparatus that performs printing operations on continuous paper P is exemplified, but the present disclosure can also be applied to an image forming apparatus that performs printing operations on cut sheets of paper.

[0106] (B-3) In the above embodiment, the light quantity is corrected as an example of an image adjustment method, but the charging voltage, developing voltage, and transfer voltage may also be adjusted.

[0107] (B-4) In the above-described embodiment, the first image adjustment is performed immediately after the image adjustment conditions are met, and the second image adjustment is performed immediately after the deteriorated toner is discharged, but the timing of these image adjustments is not particularly limited. [Explanation of symbols]

[0108] 1...printer, 10...feeder unit, 20...printing unit, 30...image forming unit, 101...roll paper, 102...feeder motor, 103...feeder transport roller, 104...tension bar, 105...paper feed sensor, 111...IN1 sensor, 112...IN2 sensor, 113...IN3 sensor, 114...transport motor, 115...transport roller group, 130...intermediate transfer belt, 131...belt support roller, 132...belt support roller, 133...belt support roller, 134...belt cleaning roller, 135...backup roller, 136...belt motor, 137...density sensor, 140...secondary transfer unit, 141...secondary transfer roller, 150...fusing unit, 151...sensor, 152...heating belt, 153...fusing backup roller, 154...fusing motor, 155...fusing Discharge sensor, 156...discharge sensor, 157...discharge roller, 160...paper discharge port, 200 (200Y, 200M, 200C, 200K, 200W)...image forming unit, 201...toner chamber, 202...supply roller, 203...developing roller, 204...layer regulating blade, 205...photosensitive drum, 206...charging roller, 207...exposure head, 208...primary transfer roller, 300...control unit, 301...main control unit, 3 10...I / F unit, 311...command decode control unit, 320...sensor control unit, 321...motor control unit, 322...secondary transfer roller control unit, 323...image formation control unit, 324...image adjustment control unit, 325...image adjustment result storage unit, 326...deteriorated toner accumulation amount storage unit, 327...deteriorated toner disposal control unit, P...continuous paper, R1...conveyance path, R2...conveyance path, Wth...deteriorated toner disposal execution threshold, Wto...deteriorated toner accumulation amount,

Claims

1. an image forming unit that forms a developer image on an image carrier; a reading unit for reading the density of the developer image for adjustment; an image adjustment result storage unit that stores the result of reading the developer image for adjustment; a deteriorated developer amount storage unit that stores an accumulated amount of deteriorated developer; an image adjustment control unit that performs a predetermined image adjustment based on a first image adjustment result stored in the image adjustment result storage unit when the accumulated amount of deteriorated developer is equal to or greater than a predetermined value, a second image adjustment result stored in the image adjustment result storage unit when the accumulated amount of deteriorated developer is less than the predetermined value, and the accumulated amount of deteriorated developer stored in the deteriorated developer amount storage unit; An image forming apparatus comprising:

2. 2. The image forming apparatus according to claim 1, wherein the predetermined image adjustment is to adjust the amount of exposure of an exposure section that forms an electrostatic latent image on the image carrier.

3. 2. The image forming apparatus according to claim 1, wherein the first image adjustment result is a result of performing image adjustment immediately after the image adjustment condition is met, and the second image adjustment result is a result of performing image adjustment immediately after the deteriorated developer is disposed of.

4. The image forming apparatus according to any one of claims 1 to 3, characterized in that the image adjustment control unit performs the specified image adjustment when there is a change in the accumulated amount of the deteriorated developer during printing and the first image adjustment result and the second image adjustment result are stored in the deteriorated developer amount memory unit.

Images