Image forming apparatus

Abstract

To accurately estimate toner consumption in an image forming apparatus in which a photoconductor drum and a developing roller are driven while in contact with each other in an operation other than that during image formation.SOLUTION: An image forming apparatus has: a photoconductor drum that carries an electrostatic latent image; an electrifying roller that electrifies the photoconductor drum; a developing roller that develops the electrostatic latent image formed on the photoconductor drum with toner; and estimation means that estimates a value related to the toner consumption, and the image forming apparatus is configured to start rotating the photoconductor drum and the developing roller in a state where both are in contact with each other. The estimation means estimates the value related to the toner consumption in the image forming apparatus on the basis of the amount of fogging toner consumed when the photoconductor drum and the developing roller are driven while in contact with each other at the start of the image forming apparatus.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus and a control method thereof. [Background technology]

[0002] In an image forming apparatus using an electrophotographic process, an image carrier such as a photosensitive drum is charged by a charging roller, an electrostatic latent image is formed by a laser scanner, and toner is transferred onto the photosensitive drum by the potential difference between the developing roller and the photosensitive drum. Outside the image forming section, there is a technique for controlling the potential difference between the developing roller and the photosensitive drum to be within a predetermined range so that the toner on the developing roller is not transferred onto the photosensitive drum. If this potential difference is not within the predetermined range, toner is likely to adhere to non-image areas, which causes an increase in toner consumption.

[0003] There is also a technique for accumulating toner consumption and estimating the remaining toner amount for the purpose of notifying a user of a decrease in the remaining toner amount at an appropriate time. When estimating the toner consumption amount, it is necessary to consider the toner consumption amount due to fogging in addition to the toner consumption amount due to image formation. The toner consumption amount due to fogging during image formation (hereinafter referred to as the fogging toner amount) correlates with the potential difference between the charging potential of the photosensitive drum and the developing bias potential. Patent Document 1 describes a technique for estimating the fogging toner amount during image formation based on this potential difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2012-189841 A Summary of the Invention [Problem to be solved by the invention]

[0005] In an image forming apparatus that starts operation with the photosensitive drum and the developing roller in contact with each other, image fog toner is generated even during operations other than image formation, such as when the image forming apparatus is started up, etc. Therefore, there is a possibility that the toner consumption amount, and therefore the remaining toner amount, cannot be accurately estimated by only estimating the amount of fog toner generated during image formation.

[0006] An object of the present invention is to accurately estimate the amount of toner consumed in an image forming apparatus that is driven in a state in which a photosensitive drum and a developing roller are in contact with each other during operations other than image formation. [Means for solving the problem]

[0007] The present invention relates to a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the toner consumption amount based on a value related to the amount of fog toner consumed when the photosensitive drum and the developing roller are driven in a contact state when the image forming apparatus is started up.

[0008] The present invention provides a method for controlling an image forming apparatus having a photosensitive drum that carries an electrostatic latent image, a charging roller that charges the photosensitive drum, and a developing roller that develops the electrostatic latent image formed on the photosensitive drum with toner, the image forming apparatus being configured to start rotating in a state in which the photosensitive drum and the developing roller are in contact with each other, the method comprising the steps of: a step of estimating a value relating to an amount of fog toner consumed when the image forming apparatus is driven in a state in which the photosensitive drum and the developing roller are in contact with each other at the time of start-up; estimating a value relating to a toner consumption amount in the image forming apparatus based on the value relating to the amount of the fog toner; The image forming apparatus control method includes the steps of:

[0009] The present invention relates to a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the toner consumption amount based on a value related to the amount of fog toner generated during non-image formation, which is different from the fog toner in non-image areas during image formation on the recording medium.

[0010] The present invention relates to a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the amount of toner consumption based on a value related to the amount of fog toner consumed when the photosensitive drum and the developing roller are driven in a contacting state during post-rotation after the image forming operation on the recording medium is completed. Effect of the Invention

[0011] According to the present invention, it is possible to accurately estimate the amount of toner consumed in an image forming apparatus that is driven in a state in which the photosensitive drum and the developing roller are in contact with each other during operations other than image formation. [Brief description of the drawings]

[0012] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a block diagram showing the functional configuration of the image forming apparatus according to the embodiment. [Diagram 3] 4 is a timing chart showing voltage control of the charging roller and the developing roller in the embodiment. [Figure 4] 3 is an enlarged view of the developing roller, the photosensitive drum, and the charging roller. [Diagram 5] 6 is a flowchart showing an estimation of the amount of fog toner consumed at the time of startup in the first embodiment. [Figure 6] 10 is a flowchart showing an estimation of the amount of fog toner consumed at the time of startup in the second embodiment. [Figure 7] 13 is a selection table of coefficient α1 in the second embodiment. [Figure 8] 13 is a flowchart showing an estimation of the amount of fog toner consumed during start-up control in the third embodiment. [Figure 9] 13 is a flowchart showing an estimation of the amount of fog toner consumed during shutdown control in the fourth embodiment. [Figure 10] 13 is a selection table of coefficient α2 in the fourth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, with reference to the drawings, a description will be given of an embodiment of the present invention. However, unless otherwise specified, the dimensions, materials, shapes, relative positions, and the like of the components described in the embodiments are not intended to limit the scope of the present invention to those alone.

[0014] The image forming apparatus in the following embodiments is characterized in that it accurately estimates the remaining toner amount by adding the fog toner amount during non-image formation to the toner consumption amount during image formation.The estimation of the fog toner amount during non-image formation is characterized in that it takes into consideration whether or not the last time the drop control was performed correctly.Examples of the time when no image formation is performed include when the image forming apparatus is started (embodiments 1 and 2), when the voltage of the charging roller and the developing roller is raised (embodiment 3), and when the voltage is lowered (embodiment 4).

[0015] Example 1 In the first embodiment, a method for estimating the amount of fog toner consumed at the start of an image forming apparatus according to the cause of the previous stop will be described.

[0016] <Configuration of Image Forming Apparatus> FIG. 1 is a schematic diagram showing an overall configuration of an image forming apparatus 100 according to a first embodiment. The image forming apparatus 100 has a process cartridge 120 that is detachable from the image forming apparatus 100. A photosensitive drum 122 made of an organic photosensitive body or an amorphous silicon photosensitive body, a charging roller 123, and a developing roller 121 are arranged in the process cartridge 120. The photosensitive drum 122 is an image carrier that carries an electrostatic latent image. The surface of the photosensitive drum 122 is uniformly charged to a predetermined potential (e.g., −400 V) by the charging roller 123. The charging roller 123 is a charging means that charges the photosensitive drum 122. The developing roller 121 is a developing means that develops the electrostatic latent image formed on the photosensitive drum 122 with toner.

[0017] A laser beam output from the scanner unit 108 is reflected by a laser reflecting mirror 107 and irradiated onto the photosensitive drum 122, causing the exposed portion of the photosensitive drum 122 to have a predetermined exposure potential (e.g., −100 V), forming an electrostatic latent image. The developing roller 121 outputs a predetermined voltage (e.g., −250 V), and forms a toner image by supplying toner with a negative charging polarity to the electrostatic latent image formed on the photosensitive drum 122. In the first embodiment, the developing roller 121 and the photosensitive drum 122 are driven in a state of constant contact with each other and are not separated from each other (hereinafter, referred to as a development contact / separation-less configuration).

[0018] Furthermore, when an image is formed, a sheet feed solenoid 113 is driven, and the topmost sheet of a stack of recording media 140 is fed from the cassette by a sheet feed roller 102. The recording medium 140 is conveyed by a conveyance roller 103 and a registration roller 104, and conveyed to a nip portion formed by a photosensitive drum 122 and a transfer roller 106. A registration sensor 105 detects the leading and trailing ends of the recording medium.

[0019] The transfer roller 106 applies a predetermined voltage and supplies charge to the rear surface of the recording medium 140, which has been conveyed to the nip portion between the photosensitive drum 122 and the transfer roller 106, thereby transferring the toner image on the photosensitive drum 122 onto the recording medium 140. The voltage applied to the transfer roller 106 is, for example, +1500 V.

[0020] <Explanation of Functional Configuration of Image Forming Apparatus> The functional configuration of the image forming apparatus 100 will be described with reference to FIG. 2. The controller 201 is capable of communicating with the host computer 200 and the engine control unit 202. When print data is input from the host computer 200, the controller 201 develops the print data and converts it into image data for image formation. The controller 201 then generates a video signal for exposure based on the image data. When the generation of the video signal is completed, CPU 220 issues a command to the video interface unit 210 of the engine control unit 202 to start image formation. After that, when the CPU 220 receives the command to start image formation from the video interface unit 210, it starts various actuators such as the main motor 250 and starts preparation for image formation. When the preparation for image formation is completed, the engine control unit 202 starts outputting a / BD signal, which is the reference timing for outputting the video signal, to the controller 201, and sequentially executes the above image formation operations.

[0021] The engine control unit 202 starts the main motor 250 as a drive source during image formation. Then, the engine control unit 202 drives each roller (feed roller 102, conveying roller 103, registration roller 104, transfer roller 106, discharge roller 110, FD roller 111) involved in conveying the recording medium 140 to control conveyance of the recording medium 140. The registration sensor 105 measures the interval of the recording medium 140 based on the detection timing of the leading end and trailing end of the recording medium 140 accompanying the conveyance of the recording medium 140. For example, the timing of the next paper feed is determined from the recording medium length and the nominal paper interval, and the paper feed solenoid 113 is driven at the paper feed timing to feed the recording medium 140.

[0022] Furthermore, the voltage control unit 230 controls the application of voltage to the charging roller 123, the developing roller 121, and the transfer roller 106. The voltage control unit 230 performs voltage control in the operation of forming an image on the photosensitive drum 122 (forming an electrostatic latent image and a toner image) and the operation of forming (transferring) an image on the recording medium 140. In addition, in preparation for these image formations, the voltage control unit 230 performs a start-up operation in which the charging roller 123 starts charging the surface of the photosensitive drum 122, and a stop-down operation after the image formation is completed. The start-up operation and the stop-down operation will be described later.

[0023] The voltage control unit 230 causes the charging roller 123 to uniformly charge the surface of the photosensitive drum 122 to a charging potential VH. When a predetermined discharge start voltage is applied to the charging roller 123, a discharge occurs in a minute space formed before and after a nip portion where the photosensitive drum 122 and the charging roller 123 contact each other. When the charge generated during the discharge moves to the photosensitive drum 122 and is charged, the potential difference between the photosensitive drum 122 and the charging roller 123 disappears and the discharge stops. As a result, the surface of the photosensitive drum 122 is controlled to a target charging potential VH. In the first embodiment, the discharge start voltage is -600V. Note that this discharge start voltage is an example.

[0024] Thereafter, the scanner unit 108 irradiates the surface of the photosensitive drum 122 with laser light, generating an exposure potential VL on the surface of the photosensitive drum 122. The area on the photosensitive drum 122 that is exposed to the exposure potential VL forms an image area, and the area on the photosensitive drum 122 that is charged to the charging potential VH forms a non-image area. The potential difference between the development bias potential Vdc applied to the development roller 121 and the charging potential VH (non-image area) is called a first potential difference, and the potential difference between the development bias potential Vdc and the exposure potential VL (image area) is called a second potential difference. If the first potential difference is Vback, when Vback deviates from a predetermined potential difference, toner adheres to the non-image area, which is known as fogging. The fogging that occurs in the non-image area results in unintended consumption of toner.

[0025] There are two types of fog: normal fog caused by toner charged to the normal polarity (negative polarity, negative toner in the first embodiment), and reverse fog caused by toner charged to the reverse polarity (positive polarity, positive toner in the first embodiment). The occurrence of normal fog and reverse fog depends on environmental conditions such as humidity and temperature, the degree of toner deterioration, the device configuration, etc.

[0026] In the image forming apparatus 100 of the first embodiment, which is driven with the photosensitive drum 122 and the developing roller 121 in contact with each other during non-image formation, fog toner may be generated in addition to the fog toner generated in the non-image area during image formation. For example, fog toner is generated during non-image formation related to preparatory operations such as when the image forming apparatus 100 is started up, when a start-up operation and a stop-down operation are performed, and during post-rotation after completion of image formation, which will be described later. In the first embodiment, the amount of fog toner generated when the image forming apparatus 100 is driven with the photosensitive drum 122 and the developing roller 121 in contact with each other during such start-up is described below. Based on the values, a value relating to the toner consumption amount in the image forming apparatus 100 is estimated.

[0027] The start-up of the image forming apparatus 100 may be, for example, a period from when the image forming apparatus 100 is turned on in a power-off state until the image forming apparatus 100 is ready to perform image formation. The start-up may be, for example, a period from when the image forming apparatus 100 is turned on in a power-off state and the application of a charging bias to the charging roller 123 is started until the image forming apparatus 100 is ready to perform image formation. The start-up may be, for example, a period from when the image forming apparatus 100 is in a power-on state and the image forming apparatus 100 is ready to perform image formation from a standby state for input of image data. The start-up may be, for example, a period from when the main motor 250 starts rotating until the position on the photosensitive drum 122 that has been charged to a potential at which an image can be formed by start-up control reaches the position of the developing roller 121.

[0028] In the image forming apparatus 100 of the first embodiment, the rotational drive is started in such a state that the photosensitive drum 122 and the developing roller 121 are in contact with each other at the time of such start-up. Therefore, depending on the potential state of the surface of the photosensitive drum 122 at the time of start-up, there is a possibility that unexpected fog toner may be generated. For example, when the power was turned off last time or when the image forming operation was completed, if a predetermined process was not performed to change from a state capable of image forming operation to a standby state or a power-off state, and the stop time is short, the charged state of the surface of the photosensitive drum 122 is in an unexpected state. Therefore, an unexpected amount of fog toner may be generated at the time of start-up.

[0029] An exposure control unit 240 performs settings on the scanner unit 108 and controls it so that the photosensitive drum 122 is exposed to a predetermined amount of light.

[0030] The toner consumption calculation unit 270 is an estimation unit that estimates the toner consumption amount in the developing roller 121. When an image is formed, the toner consumption calculation unit 270 calculates the toner consumption amount during image formation from information based on image data. The toner consumption calculation unit 270 also has a fog toner amount estimation unit 271 that estimates the fog toner amount consumed during non-image formation. In the first embodiment, the fog toner amount estimation unit 271 estimates the fog toner amount at the start of the image forming apparatus 100 as the non-image formation time. The toner consumption calculation unit 270 calculates the toner consumption amount based on the toner consumption amount during image formation and the fog toner amount consumed when the photosensitive drum 122 and the developing roller 121 are driven in a state of contact with each other during non-image formation. The toner consumption calculation unit 270 writes the calculated toner consumption amount to the non-volatile memory 124 provided in the process cartridge 120. As a result, the non-volatile memory 124 stores the cumulative value of the toner consumption amount since the process cartridge 120 was new. The cumulative value of the toner consumption amount may be stored in the non-volatile memory 260 of the engine control unit 202. The fog toner amount estimating means 271 may further estimate the amount of fog toner consumed by adhering to the non-image area of ​​the recording medium 140 during image formation. In this case, the consumed toner amount calculating unit 270 may calculate the toner consumption amount based on the amount of toner consumed in the image area during image formation, the amount of fog toner adhering to the non-image area, and the amount of fog toner during non-image formation.

[0031] The toner consumption calculation unit 270 estimates the remaining toner amount in the process cartridge 120 based on the cumulative value of the toner consumption amount and the initial toner amount contained in the process cartridge 120 when it is new. When the estimated remaining toner amount falls below a predetermined threshold, the CPU 220 performs control to notify the user of the decrease in the remaining toner amount. Various known methods can be used as the method of notification.

[0032] The environment sensor 141 and the downtime measurement unit 280 in FIG. 2 are components according to a second embodiment described later.

[0033] <Start-up and shutdown control> In the image forming apparatus 100, start-up control is performed to control the voltage applied to the charging roller 123 and the developing roller 121 in order to make the charging roller 123 and the developing roller 121 in a standby state ready for image formation. Also, stop-down control is performed to control the voltage applied to the charging roller 123 and the developing roller 121 in order to make the charging roller 123 and the developing roller 121 in an image formation ready state ready for image formation. The start-up control is performed by the voltage control unit 230 before the start of the image forming operation, and the stop-down control is performed after the end of the image forming operation. In the start-up control and stop-down control of the first embodiment, the voltage applied to the charging roller 123 and the developing roller 121 is changed stepwise to a target voltage. The start-up control and stop-down control of the first embodiment will be described below.

[0034] In the image forming apparatus of the first embodiment, the potential at which an image can be formed (an electrostatic latent image can be formed and developed with toner) is -400V for the photosensitive drum 122 and -250V for the developing roller 121. Therefore, the first potential difference Vback between the photosensitive drum 122 and the developing roller 121 in the state at which an image can be formed is 150V. When the surface potential of the photosensitive drum 122 is in a state where it is 0V, if the voltage of the charging roller 123 is set to a negative value whose absolute value is greater than the discharge start voltage of -600V, the surface potential of the photosensitive drum 122 starts to change from 0V. In order to charge the photosensitive drum 122 to -400V, it is necessary to output the voltage of the charging roller 123 to -1000V.

[0035] When the photosensitive drum 122 and the developing roller 121 are in an image forming state, even if no electrostatic latent image is formed on the surface of the photosensitive drum 122, a small amount of toner is transferred from the developing roller 121 to the photosensitive drum 122, generating fog toner. In the image forming apparatus 100 of the first embodiment, the amount of fog toner is the smallest when the first potential difference Vback is around 150V (for example, 150V±100V). When the first potential difference Vback changes significantly from 150V, the amount of fog toner increases. When the voltage of the charging roller 123 and the voltage of the developing roller 121 are raised all at once to a state in which an image can be formed, a period in which the first potential difference Vback greatly exceeds 150V may occur due to the difference in the time required for each voltage to rise. In that case, the amount of fog toner during the rise may increase.

[0036] Therefore, in order to prevent the first potential difference Vback from changing significantly from 150 V during the rise of the voltages of the charging roller 123 and the developing roller 121, the voltages of the charging roller 123 and the developing roller 121 are each changed stepwise to rise. In the first embodiment, the voltages of the charging roller 123 and the developing roller 121 are each changed to the target value in four steps of 100 V each. The voltages are also changed stepwise in a similar manner when the voltages of the charging roller 123 and the developing roller 121 are dropped.

[0037] The start-up control and the stop-down control of the charging roller 123 and the developing roller 121 in the first embodiment will be described with reference to FIG.

[0038] Figures 3(a) and 3(b) show the change in voltage when the surface potential of the photosensitive drum 122 is gradually increased from 0 V (time t1) to -400 V (time t4) at which an image can be formed. Also, Figures 3(a) and 3(b) show the change in voltage when the surface potential of the photosensitive drum 122 is subsequently decreased again to 0 V (time t8) from a state in which an image can be formed. Figure 3(a) shows the change in voltage of the charging roller 123, and Figure 3(b) shows the change in the surface potential of the photosensitive drum 122 at the position of the charging roller 123, with the vertical axis representing voltage or potential and the horizontal axis representing time.

[0039] At the base point (time t0) of the timing charts of FIGS. 3A and 3B, no voltage is applied to the charging roller 123, and the surface potential of the photosensitive drum 122 is also 0 V. At time t3, the voltage of the charging roller 123 is set to -900V. At time t4, the time T1 has elapsed since time t3, the voltage of the charging roller 123 is set to -1000V, and the charging roller 123 is ready to start image formation. At this time, the surface potential of the photosensitive drum 122 at the position of the charging roller 123 changes to -100V by the time T1 has elapsed since time t1, as shown in FIG. 3B. Thereafter, the surface potential of the photosensitive drum 122 changes by 100 V each time as the output of the charging roller 123 increases stepwise, and changes to the target value of −400 V by the time when the time T1 has elapsed from time t4.

[0040] Figures 3(c) and 3(d) are timing charts showing the changes in the voltage of the developing roller 121 and the surface potential of the photosensitive drum 122 at the position of the developing roller 121 when the surface potential of the photosensitive drum 122 at the position of the charging roller 123 is changed as described above. Figure 3(c) shows the change in voltage of the developing roller 121. Figure 3(d) shows the change in the surface potential of the photosensitive drum 122 when the surface of the photosensitive drum 122, which was at the position of the charging roller 123 at time tn (n = 0, 1, 2, ...) in Figure 3(b), reaches the position of the developing roller 121 at time tn'. The vertical axis of Figures 3(c) and 3(d) represents voltage or potential, and the horizontal axis represents time.

[0041] A positive or negative bias can be applied to the developing roller 121 in the first embodiment as a developing bias. At the base point (time t0') of the timing charts in FIG. 3(c) and FIG. 3(d), a positive voltage of +150V is applied to the developing roller 121 in order to set the first potential difference Vback between the photosensitive drum 122 and the developing roller 121 to 150V, which is a target value in a state in which an image can be formed. Time t1' is the timing at which the surface of the photosensitive drum 122, which was at the position of the charging roller 123 at time t1 in FIG. 3(a) and FIG. 3(b), reaches the position of the developing roller 121. In the first embodiment, the interval between time t1 and time t1' is 100 msec (t1'-t1=100 msec). At time t1', the developing voltage applied to the developing roller 121 is changed by 100 V, the same as the change width in the charging voltage applied to the charging roller 123, and set to +50 V. At time t2', which is the time T1 that has passed since time t1', the voltage of the developing roller 121 is similarly changed by 100 V and set to -50 V. At time t3', which is the time T1 that has passed since time t2', the voltage of the developing roller 121 is set to -150 V. Similarly, at time t4', which is the time T1 that has passed since time t3', the voltage of the developing roller 121 is set to -250 V, completing preparations in the developing roller 121 for image formation.

[0042] The voltages applied to the charging roller 123 and the developing roller 121 are changed in stages. As a result, the first potential difference Vback between the charging roller 123 and the developing roller 121 changes from 150V within 100V from time t0' to time t4' in Figures 3(c) and 3(d). Therefore, even if there is variation due to individual differences in the time required for the voltage rise of the charging roller 123 and the developing roller 121, the value of the first potential difference Vback can be kept within the range of 150V ± 100V, and an increase in the amount of fog toner can be suppressed.

[0043] In addition, in the fall control at times t5 to t8 and times t5' to t8', the voltage applied to the charging roller 123 is changed stepwise in the same manner as in the rise control described above, so that the value of the first potential difference Vback can be kept within a range in which fogging toner is unlikely to occur. However, in the fall control, the voltage applied to the charging roller 123 is lowered, and control is performed to attenuate the charge of the photosensitive drum 122 by applying a transfer bias and performing pre-exposure to expose and eliminate electricity upstream of the charging roller 123. The voltage control in the rise control and fall control described above is an example, and is not limited to the above example.

[0044] <Estimation of fog toner amount> A method for estimating the amount of fog toner consumed at the start of the image forming apparatus 100 will be described. In the first embodiment, the amount of fog toner consumed at the next start of the image forming apparatus 100 is estimated in the case where the image forming apparatus 100 was previously stopped due to an interruption during the image forming operation as a non-image forming time.

[0045] If the image forming operation is interrupted for some reason and the voltage control unit 230 does not perform the drop control, the value of the first potential difference Vback may not be within the range of 150V±100V when the image forming apparatus 100 is started next time. In Fig. 4(a) and Fig. 4(b), the area from the position of the charging roller 123 to the position of the developing roller 121 on the surface of the photosensitive drum 122 is indicated by a diagonal line. In this area, the surface potential cannot be controlled by the voltage control of the developing roller 121 and the charging roller 123 when the image forming apparatus 100 is started next time. Regardless of whether the drop control is performed or not, the surface potential of the photosensitive drum 122 attenuates with the passage of time since the end of the previous image forming operation. Under the same condition of the elapsed time after the end of the image forming operation, when the drop control is not performed after the previous image forming operation, a lot of fog toner may be generated, even if the rise control is properly performed at the next start, compared to when the drop control is performed. However, when the elapsed time is sufficiently long and the surface potential of the photosensitive drum 122 becomes 0, there is no difference in the generation of fog toner depending on whether or not the turn-off control is performed, so the above-mentioned elapsed time is the elapsed time for which the surface potential does not become 0. Note that in the first embodiment, since the developing roller 121 and the photosensitive drum 122 start rotating in a state of contact with each other at the time of startup, if the turn-off control was not performed the previous time, unexpected fog toner may be generated at the time of the next startup depending on the stop time. Therefore, in the first embodiment, the amount of fog toner at startup is estimated taking into consideration whether or not the turn-off control was performed after the previous image forming operation.

[0046] Specifically, the engine control unit 202 writes a value defined as follows, for example, to a specific address in the non-volatile memory 260 according to the operating state of the image forming apparatus 100. 00h: Image formation is not in progress 01h: Image formation in progress

[0047] Here, the timing determined as "image forming operation in progress" is when the operation of forming an image on the photosensitive drum 122, the operation of forming (transferring) an image on the recording medium 140, start-up control for these preparatory operations, or shut-down control for the subsequent operation is being executed. With regard to the start-up control, the image forming operation is determined to be in progress from the timing when the charging roller 123 starts rotating and is charged. With regard to the shut-down control, the image forming operation is determined to be in progress from the timing when the charging roller 123 becomes uncharged and the rotation of the charging roller 123 stops. Therefore, the engine control unit 202 writes 01h to the address of the non-volatile memory 260 at the timing when the voltage control unit 230 starts the start-up control and the charging roller 123 starts rotating. The charging roller 123 may be configured to rotate following the photosensitive drum 122, or may be configured to rotate and driven by an independent driving device. Furthermore, the engine control unit 202 writes 00h to the address of the non-volatile memory 260 at the completion of the shut-down control. If the image forming operation is interrupted while the shutdown control is not completed, 01h is written to the address in non-volatile memory 260. Therefore, when the next startup is performed, if 01h is written by referring to the address in non-volatile memory 260, it can be determined that the previous shutdown control was not completed. In this way, control that takes into account the cause of the shutdown of image forming apparatus 100 is possible.

[0048] The toner consumption calculation unit 270 calculates the amount of fog toner consumed at the time of startup using the fog toner amount estimation unit 271. If the shutdown control was not performed normally at the end of the previous image forming operation, the charge roller 123 and the photosensitive drum 122 are consumed at the time of startup of the image forming apparatus 100. It is not possible to control the potential of the region from the position where the developing roller 121 and the photosensitive drum 122 contact each other to the position where the developing roller 121 and the photosensitive drum 122 contact each other. It is considered that the amount of fog toner consumed at the start of the image forming apparatus 100 is generated according to the size of this potential uncontrollable region (the region indicated by the diagonal line in FIG. 4). Therefore, the fog toner amount estimating means 271 estimates the amount of fog toner [g] consumed at the next start of the image forming apparatus 100 by the following formula 1 when the shutdown control was not performed normally after the previous image forming operation. Fog toner amount = D1 × L × α1 Formula 1 D1 [mm]: the distance in the rotational direction along the surface of the photosensitive drum 122 of the potential uncontrollable region (see FIG. 4(a)), and indicates the size of the potential uncontrollable region. L [mm]: length of the developing opening 121A in the toner container 121B in the direction of the rotation axis of the developing roller 121 (length of the toner coated region 121C of the developing roller 121) (see Figs. 4(b) and 4(c)). Fig. 4(c) is a conceptual diagram showing the relationship between the developing opening 121A of the toner container 121B, which rotatably supports the developing roller 121 and contains toner, and the developing roller 121. The toner in the toner container 121B is supplied to the developing roller 121 from the developing opening 121A, and the surface of the developing roller 121 is coated with the toner. Therefore, fogging occurs in the region 121C (shown by diagonal lines in Fig. 4(c)) of the surface of the developing roller 121 in the longitudinal direction (direction of the rotation axis) that is the length of the developing opening 121A. α1 [g / mm 2 ]: experimentally determined coefficient. In Example 1, α1 = 3.0 × 10 -7 [mg / mm 2 ], L=210[mm], D1=18[mm].

[0049] FIG. 5 is a flowchart showing a process for estimating the amount of fog toner consumed at the start-up of the image forming apparatus 100 according to the first embodiment.

[0050] In step S501, the fog toner amount estimating means 271 judges whether or not shutdown control has been performed after the previous image forming operation. That is, when the image forming apparatus 100 starts up, the fog toner amount estimating means 271 judges whether the previous stop was a stop after shutdown control or a stop due to interruption of the image forming operation by referring to the non-volatile memory 260. If shutdown control has not been performed (if the cause of the stop is a stop due to interruption of the image forming operation) (S501: No), in step S502, the fog toner amount estimating means 271 calculates the amount of fog toner consumed at startup using formula 1.

[0051] In step S503, the consumed toner amount calculation unit 270 adds a value equivalent to the fog toner amount calculated in step S502 to the consumed toner amount. Note that the fog toner amount calculated here is an estimated value and does not necessarily match the actual fog toner amount. Therefore, "adding" to the consumed toner amount here includes adding the fog toner amount equivalent value calculated by formula 1 to the actual toner consumption amount. The accumulated value of the consumed toner amount up to now is stored in the non-volatile memory 124 of the process cartridge 120, and the consumed toner amount calculation unit 270 writes the consumed toner amount updated by adding the fog toner amount to the non-volatile memory 124. Note that the accumulated value of the consumed toner amount may be stored in the non-volatile memory 260 provided in the image forming apparatus 100.

[0052] As described above, in the first embodiment, when the image forming operation is interrupted in the image forming apparatus 100 and shutdown control is not performed, the amount of fog toner consumed at the next startup is estimated and added to the amount of toner consumed. This makes it possible to estimate the remaining amount of toner with high accuracy. Note that, in the first embodiment, the method of estimating the amount of fog toner at startup using formula 1 and adding it to the amount of toner consumed is exemplified, but the method of estimating the amount of fog toner is not limited to this example. Fog Toner Amount Estimation The determining means 271 is not limited to estimating the fog toner amount itself, so long as it estimates a value related to the fog toner amount. Furthermore, the method of calculating the toner consumption amount is not limited to adding a value related to the fog toner amount. For example, a fixed amount may be added to the toner consumption amount as the fog toner amount at startup. Furthermore, the amount to be calculated is not limited to the fog toner amount, and an amount correlated or related to the fog toner amount may be calculated. For example, when a pixel count (number of dots) is used to calculate the remaining toner amount, a value equivalent to the fog toner amount may be calculated by converting it into the number of pixels, and added to the number of pixels calculated in the remaining toner amount calculation process. Furthermore, the fog amount at startup may be estimated by multiplying the toner consumption amount by a predetermined coefficient.

[0053] Example 2 In the second embodiment, a method for estimating the amount of fog toner consumed at the start of the image forming apparatus 100 is described, taking into consideration factors that change the amount of fog toner, such as the degree of toner deterioration, the elapsed time from the stop due to the interruption of the image forming operation to the next start, and the surrounding environment. Below, a description of the configuration common to the first embodiment is omitted.

[0054] The amount of fog toner changes depending on the first potential difference Vback as well as environmental conditions such as the degree of toner deterioration and the surrounding humidity.

[0055] Toner is supplied to the developing roller 121 through a developing opening 121A of a toner container 121B shown in FIG. 4(c) in the process cartridge 120. The toner in the toner container is stirred by a stirring sheet in the toner container while the main motor 250 is driving. In general, toner deteriorates when stirred, which affects the polarity of the toner. The polarity of the toner affects the amount of fog toner. When the engine control unit 202 drives the main motor 250, it writes a value corresponding to the number of stirrings (hereinafter, referred to as the number of rubbings) into the non-volatile memory 124 of the process cartridge 120 as an index of the degree of deterioration of the toner. In the second embodiment, the fog toner amount estimating means 271 obtains information on the number of rubbings from the non-volatile memory 124, and estimates the amount of fog toner at the time of startup based on the number of rubbings.

[0056] Also, when the image forming operation is interrupted, the first potential difference Vback immediately after the interruption is the value during image formation. As time passes after the image forming operation is interrupted, the surface potential of the photosensitive drum 122 drops, and the first potential difference Vback eventually becomes 0V. For example, when the image forming operation is interrupted while the charging bias is applied at -1000V, the developing bias becomes 0V, and the first potential difference Vback changes from 150V to 400V. Thereafter, the surface potential of the photosensitive drum 122 gradually attenuates to 0V, and the first potential difference Vback also becomes 0V. When the image forming operation is interrupted, the stop time measurement unit 280 (see FIG. 2) measures the elapsed time (hereinafter, referred to as stop time) since the image forming operation was stopped, and stops the measurement when the operation is started again. Therefore, in the second embodiment, the fogging toner amount estimation unit 271 estimates the fogging toner amount at the time of start based on the stop time measured by the stop time measurement unit 280.

[0057] The amount of toner consumed due to regular fogging caused by toner charged to the regular polarity (negative polarity, negative toner in Example 1) tends to decrease as the number of rubbings increases and the toner deteriorates. Also, the amount of fogging toner consumed at the next startup tends to decrease as the downtime increases. On the other hand, for toner charged to the opposite polarity (positive polarity, positive toner in Example 2), the amount of charge of the toner tends to decrease as the number of rubbings increases, so that reverse fogging caused by positive toner tends to increase as the number of rubbings increases. Also, the amount of reverse fogging tends to increase as the downtime increases. If the downtime increases, the charge of the toner remaining on the developing roller 121 (after passing the developing blade, but not passing the developing blade at startup) attenuates and becomes smaller (shifts to the positive side).

[0058] In Example 2, the environment or configuration is such that regular fog due to regular polarity toner is likely to occur. The estimated value of the fog toner amount based on the number of rubbings and the downtime is adjusted depending on whether the environment or configuration is such that reverse fog due to reversely charged toner is likely to occur. For example, under conditions where normal fog is likely to occur, the fog toner amount at startup is estimated to be smaller the more the number of rubbings, and the longer the downtime, the fog toner amount at startup is estimated to be smaller. Also, under conditions where reverse fog is likely to occur, the fog toner amount at the next startup (reverse fog toner amount) is estimated to be larger the more the number of rubbings and the longer the downtime.

[0059] Furthermore, the amount of fog toner at startup varies depending on environmental conditions such as temperature and humidity. The environmental sensor 141 (see FIG. 2) measures a predetermined environmental condition of the image forming apparatus 100. In the second embodiment, the fog toner amount estimation means 271 estimates the amount of fog toner at startup according to the environmental condition measured by the environmental sensor 141. Since the relationship between the environmental condition and the amount of fog toner depends on the type of environmental condition, the physical properties of the toner, and the like, information on the relationship between the environmental condition and the amount of fog toner obtained in advance through experiments is stored in the non-volatile memory 260.

[0060] In the second embodiment, the relationship between the number of rubbing operations, downtime, and environmental conditions and the coefficient α1 of Equation 1 used to estimate the amount of fog toner is obtained in advance and stored in the non-volatile memory 260 as a table as shown in Fig. 7. The fog toner amount estimation means 271 determines the coefficient α1 by referring to the table in Fig. 7 based on the number of rubbing operations obtained from the non-volatile memory 124, the downtime measured by the downtime measurement unit 280, and the environmental conditions measured by the environmental sensor 141. Then, the fog toner amount is calculated by Equation 1 using the determined coefficient α1.

[0061] FIG. 6 is a flowchart showing a process for estimating the amount of fog toner consumed at the start-up of the image forming apparatus 100 according to the second embodiment.

[0062] In step S601, the fog toner amount estimation means 271 judges whether or not the shutdown control was performed after the previous image forming operation. That is, the fog toner amount estimation means 271 judges the cause of the previous stop of the image forming apparatus 100. If the shutdown control was not performed (S601: No), the process of step S6011 is executed. In step S6011, the fog toner amount estimation means 271 judges whether the elapsed time (stop time) from the previous stop exceeds a threshold value. If the stop time exceeds the threshold value, the surface potential of the photosensitive drum 122 is completely lowered, and unexpected fog does not occur. Therefore, since it is not necessary to estimate the fog toner amount at the time of startup, the process of this flowchart is terminated. On the other hand, if the stop time is equal to or less than the threshold value, the surface potential of the photosensitive drum 122 is in an uncontrolled state, and there is a possibility that unexpected fog may occur, so the process of estimating the fog toner amount thereafter is executed.

[0063] In step S602, the consumed toner amount calculation unit 270 determines a coefficient α1. If the stop time exceeds the threshold, the coefficient α1 may be determined to be, for example, 0, or may be set to a smaller value than when the stop time does not exceed the threshold. Then, in step S603, the consumed toner amount calculation unit 270 calculates the fog toner amount using Equation 1. In step S604, the consumed toner amount calculation unit 270 adds the consumed toner amount estimated to the consumed toner.

[0064] As described above, in the second embodiment, when the image forming operation is interrupted in the image forming apparatus 100 and shutdown control is not performed, the amount of fog toner consumed at the next startup is estimated and added to the toner consumption amount. Furthermore, in estimating the amount of fog toner, the amount of fog toner consumed at startup can be estimated more accurately by taking into account the degree of toner deterioration, environmental conditions, and, in the case of startup after an image forming operation is interrupted, the downtime. Therefore, the remaining toner amount can be estimated with high accuracy. Note that, in the second embodiment, a method for estimating the amount of fog toner based on three conditions, the number of rubbings, environmental conditions, and downtime, has been described, but the amount of fog toner can also be estimated based on any one of these conditions, or a combination of any two of them. This is also fine.

[0065] Example 3 The image forming apparatus 100 in the first and second embodiments has a development contact / separation-less configuration, and the development roller 121 and the photosensitive drum 122 are in contact with each other even when the image forming operation is not performed. Therefore, the fog toner is consumed even when the development roller 121 and the photosensitive drum 122 are driven during start-up control, shut-down control, and other non-image forming operations.

[0066] In the third embodiment, a method of estimating the amount of fog toner during execution of start-up control will be described as an estimation method for the amount of fog toner during non-image formation.

[0067] In the third embodiment, when the shutdown control is performed after the previous image forming operation, the fog toner amount [g] in the next startup control is estimated by the following formula 2. Fog toner amount = D2 × L × α2 Formula 2 D2 [mm]: the distance in the rotational direction along the surface of the photosensitive drum 122 that passes through the developing roller 121 during start-up control (hereinafter referred to as driving distance), and represents the driving amount of the photosensitive drum 122 during start-up control. L [mm]: the length of the developing opening 121A in the toner container 121B in the rotation axis direction of the developing roller 121 (the length of the toner coated area 121C of the developing roller 121) (see FIGS. 4(b) and 4(c)). α2 [g / mm 2 ]: experimentally determined coefficient.

[0068] The coefficient α2 is experimentally determined in the same manner as the coefficient α1 in the formula 1. As with the coefficient α1 in the second embodiment, the coefficient α2 may be determined based on the number of times of rubbing, environmental conditions, and the like.

[0069] On the other hand, as in the first embodiment, the surface potential of the photosensitive drum 122 decays with time after the end of the previous image forming operation, regardless of whether or not the lowering control is performed. Under the same condition of the elapsed time after the end of the image forming operation, if the lowering control is not performed after the previous image forming operation, a large amount of fog toner may be generated even if the start-up control is properly performed at the next startup, compared to the case where the lowering control is performed. However, if the elapsed time is sufficiently long and the surface potential of the photosensitive drum 122 becomes 0, there is no difference in the generation of fog toner depending on whether or not the lowering control is performed, so the above-mentioned elapsed time is an elapsed time that does not make the surface potential 0. Note that in the third embodiment, since the developing roller 121 and the photosensitive drum 122 start rotating in a state of contact at the time of startup, fog toner will be generated at the next startup if the previous lowering control was not performed. In the third embodiment, the amount of fog toner generated in the potential uncontrollable area described in the first embodiment among the amount of fog toner in the next startup control is calculated using the coefficient α1 and the length D1 of the potential uncontrollable area. In addition, the driving distance D2 of the photosensitive drum 122 in the start-up control is longer than the length D1 of the potential uncontrollable region. The amount of fog toner occurring outside the potential uncontrollable region is calculated using the coefficient α2 and the distance D2-D1 of the driving distance D2 that exceeds the length D1 of the potential uncontrollable region. Therefore, the amount of fog toner [g] in the next start-up control when the stop-down control has not been performed after the previous image forming operation is estimated by the following formula 3. Fog toner amount = (D2-D1) x L x α2 + D1 x L x α1 (where D2>D1) Formula 3

[0070] The length D1 of the potential uncontrollable region is a constant determined by the dimensions and arrangement of the developing roller 121, the photosensitive drum 122, and the charging roller 123 in the image forming apparatus 100, while the driving distance D2 during start-up control is a variable control parameter during start-up control. If the stop time since the previous time is sufficiently long and the charge in the potential uncontrollable region D1 has sufficiently decayed, it is considered that the cause of fog toner generation is only the region of the driving distance D2, and the calculation may be performed with D1=0.

[0071] FIG. 8 is a flowchart showing a process for estimating the amount of fog toner consumed during start-up control of the voltage control unit 230 in the third embodiment.

[0072] When the start-up control starts, in step S801, the fog toner amount estimating means 271 determines the coefficient α2.

[0073] In step S802, the fog toner amount estimating means 271 judges whether or not shutdown control has been performed after the previous image forming operation. That is, the fog toner amount estimating means 271 refers to the non-volatile memory 260 and judges whether the previous stop was a stop after shutdown control or a stop due to interruption of the image forming operation. If shutdown control has been performed (if the previous stop was a stop after shutdown control) (S802: Yes), in step S803, the fog toner amount estimating means 271 calculates the fog toner amount by Equation 2. On the other hand, if shutdown control has not been performed (if the previous stop was due to interruption of the image forming operation) (S802: No), the process of step S8021 is executed.

[0074] In step S8021, the fog toner amount estimation means 271 determines whether the elapsed time (stop time) since the previous stop exceeds a threshold value. If the stop time exceeds the threshold value, the surface potential of the photosensitive drum 122 is completely lowered, and no unexpected fog occurs. Therefore, since there is no need to estimate the fog toner amount at the time of startup, the process of this flowchart ends. On the other hand, if the stop time is equal to or less than the threshold value, the surface potential of the photosensitive drum 122 is in an uncontrolled state, and there is a possibility that unexpected fog occurs, so the fog toner amount estimation process is executed thereafter. In step S804, the fog toner amount estimation means 271 determines a coefficient α1. Then, in step S805, the fog toner amount estimation means 271 calculates the amount of fog toner by Equation 3.

[0075] In step S806, the consumed toner amount calculation unit 270 adds the consumed fog toner amount calculated in step S803 or step S805 to the consumed toner.

[0076] As described above, in the third embodiment, by considering the amount of fog toner consumed during non-image formation, the toner consumption amount can be estimated more accurately, and the remaining toner amount can be estimated more accurately. In the third embodiment, the amount of fog toner during start-up control is estimated based on whether or not the stop control was executed when the previous image formation operation was stopped (whether or not the stop was due to an interruption during the image formation operation). Therefore, the amount of fog toner can be estimated more accurately. Note that in the third embodiment, a method for estimating the amount of fog toner during start-up control has been described, but similarly, the amount of fog toner during the execution of the stop control as the non-image formation time may be estimated and added to the amount of consumed toner. The amount of fog toner during the execution of the stop control can be estimated by using the driving distance D3 representing the driving amount of the photosensitive drum 122 during the stop control in place of the driving distance D2 in Equation 2.

[0077] Example 4 In the fourth embodiment, when a voltage control sequence different from the normal shutdown control is executed during shutdown control after an image forming operation, a method for estimating the amount of fog toner consumed during non-image formation after an image forming operation according to the voltage control sequence executed is described.

[0078] In addition to the configuration of the third embodiment, the image forming apparatus 100 of the fourth embodiment performs charging roller cleaning, which is a maintenance operation of the image forming apparatus 100, as necessary during shutdown control in order to prepare for the next image forming operation. Specifically, a positive voltage and a negative voltage are applied to the surface potential of the photosensitive drum 122 at a predetermined timing. When the charging roller cleaning is performed, a voltage control sequence different from that during normal shutdown control is performed for the surface potential of the photosensitive drum 122, and therefore a different amount of fog toner is generated than during normal shutdown control. When the image forming operation is completed and charging roller cleaning is required, the voltage control unit 230 performs charging roller cleaning, which is a voltage control sequence different from the normal shutdown control sequence.

[0079] In the fourth embodiment, when a voltage control sequence different from the normal stop control is executed for the developing roller 121 and the charging roller 123 during the stop control, the coefficient α2 is determined according to the voltage control sequence. Using this coefficient α2, the amount of fog toner during the stop control is calculated by Equation 2. In the fourth embodiment, the relationship between the type of voltage control sequence and the coefficient α2 of Equation 2 used to estimate the amount of fog toner during the stop control is obtained in advance by experiment, and is stored in the non-volatile memory 260 as a table as shown in FIG. 10. The coefficient α2 corresponding to each voltage control sequence may be determined based on the number of rubbings, environmental conditions, etc., as in the second embodiment.

[0080] The fogging toner amount estimating means 271 determines the coefficient α2 by referring to the table in Fig. 10 according to the type of voltage control sequence executed by the voltage control unit 230 in the shutdown control. Then, the fogging toner amount during the shutdown control is calculated by the formula 2 using the determined coefficient α2.

[0081] FIG. 9 is a flowchart showing a process for estimating the fog toner consumed during the shutdown control in the fourth embodiment.

[0082] When the shutdown control starts, in step S901, the fog toner amount estimating means 271 determines the coefficient α2.

[0083] In step S902, the fog toner amount estimating means 271 calculates the amount of fog toner according to Equation 2 using the coefficient α2 determined in step S901.

[0084] In step S903, the consumed toner amount calculation unit 270 adds the consumed fog toner amount calculated in step S902 to the consumed toner.

[0085] As described above, in the fourth embodiment, the fog toner consumed during non-image formation is estimated according to the voltage control sequence executed during non-image formation, so that the fog toner amount can be estimated with higher accuracy. As a result, the remaining toner amount can be estimated with higher accuracy. Note that in the fourth embodiment, the charging roller cleaning during the shutdown control is described as an example of the voltage control sequence during non-image formation, but the voltage control sequence is not limited to this.

[0086] (Other Examples) The present invention can also be realized by a process in which a program for implementing one or more of the functions of the above-mentioned embodiments is supplied to a system or device via a network or a storage medium, and one or more processors in a computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that implements one or more of the functions.

[0087] The disclosure of this embodiment includes the following configuration. (Configuration 1) a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the toner consumption amount based on a value related to the amount of fog toner consumed when the photosensitive drum and the developing roller are driven in contact with each other at the time of start-up of the image forming apparatus. (Configuration 2) 2. The image forming apparatus according to configuration 1, wherein the start-up time is the next start-up time of the image forming apparatus in a case where the previous stop of the image forming operation was due to an interruption during the image forming operation. (Configuration 3) The image forming apparatus according to configuration 1, wherein the startup time is the next startup time of the image forming apparatus when the previous image forming operation was stopped due to an interruption during the image forming operation and the elapsed time since the previous stop is less than or equal to a threshold value. (Configuration 4) The image forming apparatus according to configuration 1, wherein the startup time is a time of executing start-up control for controlling the voltage applied to the charging roller and the developing roller to bring the charging roller, the photosensitive drum, and the developing roller, which are in a standby state, into a state capable of forming an image. (Configuration 5) 5. The image forming apparatus according to configuration 4, wherein the estimation unit estimates a value relating to an amount of fog toner during the start-up control based on a drive amount of the photosensitive drum during the start-up control. (Configuration 6) The image forming apparatus according to configuration 5, wherein the estimation means estimates a value relating to the amount of fog toner at the time of the start-up control, based further on whether or not a stop-down control was executed at the time the previous image forming operation was stopped, in which the voltage applied to the charging roller and the developing roller was controlled to put the charging roller and the developing roller, which are in a state capable of image formation, into a standby state. (Configuration 7) The image forming apparatus according to configuration 1, wherein the startup time is a time of executing shutdown control for controlling the voltage applied to the charging roller and the developing roller to put the charging roller, the photosensitive drum, and the developing roller, which are in a state capable of forming an image, into a standby state. (Configuration 8) 8. The image forming apparatus according to configuration 7, wherein the estimation unit estimates a value relating to an amount of fog toner during the stop control based on a drive amount of the photosensitive drum during the stop control. (Configuration 9) 9. The image forming apparatus according to configuration 8, wherein the estimation unit estimates a value relating to an amount of fog toner during the stop control, further based on voltage control executed on the charging roller and the developing roller during execution of the stop control. (Configuration 10) The image forming apparatus according to any one of configurations 1 to 9, wherein the estimation means estimates a value relating to the amount of fog toner at the time of startup based on the size of an area on the surface of the photosensitive drum from a position where the charging roller and the photosensitive drum contact each other to a position where the developing roller and the photosensitive drum contact each other. (Configuration 11) 11. The image forming apparatus according to any one of configurations 1 to 10, wherein the estimation means estimates a value relating to the remaining amount of toner in the developing roller based on a value relating to an initial amount of toner and a cumulative value relating to the amount of toner consumed. (Configuration 12) The estimation means includes: A value relating to the amount of toner adhering to the image area of ​​the photosensitive drum during image formation and the amount of fog toner adhering to the non-image area; a value relating to the amount of fog toner consumed when the image forming apparatus is driven in a state in which the photosensitive drum and the developing roller are in contact with each other at the time of start-up; 11. The image forming apparatus according to any one of configurations 1 to 10, wherein the value relating to the toner consumption amount is estimated based on the above. (Configuration 13) 13. The image forming apparatus according to any one of configurations 1 to 12, wherein the estimation means estimates a value relating to the amount of the fog toner based on a degree of deterioration of the toner. (Configuration 14) 13. The image forming apparatus according to any one of configurations 1 to 12, wherein the estimation means estimates the value relating to the amount of fog toner based on the time that has elapsed since the previous image forming operation was stopped. (Configuration 15) 13. The image forming apparatus according to any one of configurations 1 to 12, wherein the estimation means estimates the value relating to the amount of fog toner based on whether or not the previous stop of the image forming operation was due to an interruption during the image forming operation. (Configuration 16) an environmental sensor for measuring an environmental condition around the image forming apparatus; 13. The image forming apparatus according to any one of configurations 1 to 12, wherein the estimation unit estimates a value relating to the amount of the fog toner based on the environmental condition measured by the environmental sensor. (Configuration 17) 17. The image forming apparatus according to any one of Configurations 1 to 16, wherein the developing roller and the photosensitive drum are driven in a state of being constantly in contact with each other. (Configuration 18) 8. The image forming apparatus according to any one of Configurations 5 to 7, wherein in the start-up control, the voltages applied to the charging roller and the developing roller are changed stepwise up to target voltages. (Configuration 19) 10. The image forming apparatus according to any one of Configurations 6 to 9, wherein in the fall control, the voltages applied to the charging roller and the developing roller are changed stepwise to a target voltage. (Method 20) A method for controlling an image forming apparatus having a photosensitive drum that carries an electrostatic latent image, a charging roller that charges the photosensitive drum, and a developing roller that develops the electrostatic latent image formed on the photosensitive drum with toner, the image forming apparatus being configured to start rotating in a state in which the photosensitive drum and the developing roller are in contact with each other, comprising the steps of: a step of estimating a value relating to an amount of fog toner consumed when the image forming apparatus is driven in a state in which the photosensitive drum and the developing roller are in contact with each other at the time of start-up; estimating a value relating to a toner consumption amount in the image forming apparatus based on the value relating to the amount of the fog toner; 11. A method for controlling an image forming apparatus comprising: (Configuration 21) a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the toner consumption amount based on a value related to the amount of fog toner generated during non-image formation, which is different from the fog toner in non-image areas during image formation on the recording medium. (Configuration 22) a photosensitive drum that carries an electrostatic latent image; a charging roller for charging the photosensitive drum; a developing roller for developing the electrostatic latent image formed on the photosensitive drum with toner; an estimation means for estimating a value relating to toner consumption; and an image forming apparatus configured to start rotating in a state where the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value related to the amount of toner consumption based on a value related to the amount of fog toner consumed when the photosensitive drum and the developing roller are driven in a contact state during post-rotation after the image forming operation on the recording medium is completed. [Explanation of symbols]

[0088] 121: developing roller, 122: photosensitive drum, 123: charging roller, 270: toner consumption amount calculation unit, 271: fog toner amount estimation means

Claims

1. A photosensitive drum that carries an electrostatic latent image, A charging roller for charging the photosensitive drum, A developing roller that develops the electrostatic latent image formed on the photosensitive drum using toner, An estimation means for estimating values ​​related to toner consumption, An image forming apparatus having a photosensitive drum and a developing roller, configured to start rotating when the photosensitive drum and the developing roller are in contact with each other, The image forming apparatus is characterized in that the estimation means estimates a value relating to toner consumption based on a value relating to the amount of fouling toner consumed when the photosensitive drum and the developing roller are driven in contact with each other at the time the image forming apparatus is started.

2. The image forming apparatus according to claim 1, wherein the startup is the next startup of the image forming apparatus when the previous stop of the image forming operation was due to an interruption during the image forming operation.

3. The image forming apparatus according to claim 1, wherein the startup is the next startup of the image forming apparatus when the previous stop of the image forming operation was due to an interruption during the image forming operation, and the elapsed time since the previous stop is less than or equal to a threshold.

4. The image forming apparatus according to claim 1, wherein the startup is the time when startup control is performed to control the voltage applied to the charging roller and the developing roller in order to bring the charging roller, the photosensitive drum, and the developing roller, which are in a standby state, into a state where they can form an image.

5. The image forming apparatus according to claim 4, wherein the estimation means estimates a value relating to the amount of toner fouling during the startup control based on the amount of drive of the photosensitive drum in the startup control.

6. The image forming apparatus according to claim 5, wherein the estimation means estimates a value relating to the amount of fouling toner at the time of the start-up control, based on whether or not a drop-down control was performed at the time of the previous stop of the image forming operation to control the voltage applied to the charging roller and the developing roller in order to put the charging roller and the developing roller, which are in an image forming state, into a standby state.

7. The image forming apparatus according to claim 1, wherein the startup is during the execution of a drop-down control that controls the voltage applied to the charging roller and the developing roller in order to put the charging roller, the photosensitive drum, and the developing roller, which are in an image-forming state, into a standby state.

8. The image forming apparatus according to claim 7, wherein the estimation means estimates a value relating to the amount of toner fouling during the fall-down control based on the amount of drive of the photosensitive drum during the fall-down control.

9. The image forming apparatus according to claim 8, wherein the estimation means estimates a value relating to the amount of fouled toner during the fall-down control, based on voltage control performed on the charging roller and the developing roller during the execution of the fall-down control.

10. The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the amount of fouled toner at startup based on the size of the region on the surface of the photosensitive drum from the position where the charging roller and the photosensitive drum come into contact to the position where the developing roller and the photosensitive drum come into contact.

11. The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the remaining amount of toner in the developing roller based on a value relating to the initial amount of toner and a cumulative value relating to the amount of toner consumed.

12. The estimation means is, Values ​​relating to the amount of toner adhering to the image area of ​​the photosensitive drum and the amount of fouling toner adhering to the non-image area during image formation, A value relating to the amount of foul toner consumed when the photosensitive drum and the developing roller are driven in contact with each other during startup of the image forming apparatus, An image forming apparatus according to any one of claims 1 to 9, which estimates a value relating to the amount of toner consumed based on the above.

13. The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the amount of fouled toner based on the degree of deterioration of the toner.

14. The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the amount of toner fouling based on the elapsed time since the previous image forming operation stopped.

15. The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the amount of toner fouling based on whether the previous stop of the image forming operation was due to an interruption during the image forming operation.

16. The image forming apparatus has an environmental sensor that measures the surrounding environmental conditions, The image forming apparatus according to any one of claims 1 to 9, wherein the estimation means estimates a value relating to the amount of fouling toner based on the environmental conditions measured by the environmental sensor.

17. The image forming apparatus according to any one of claims 1 to 9, wherein the developing roller and the photosensitive drum are driven in a state where they are always in contact with each other.

18. The image forming apparatus according to any one of claims 4 to 6, wherein the startup control involves gradually changing the voltage applied to the charging roller and the developing roller up to a target voltage.

19. The image forming apparatus according to any one of claims 6 to 9, wherein in the drop-down control, the voltage applied to the charging roller and the developing roller is changed stepwise up to a target voltage.

Images