JP2019015903A - Image forming apparatus and image forming method - Google Patents

Abstract

To provide an image forming apparatus that can stably maintain image quality.SOLUTION: The image forming apparatus comprises: an image carrier that includes a surface carrying an image; an exposure device that exposes the surface of the image carrier; contact members that are respectively in contact with both the surface of the image carrier and exposure device to adjust the interval between the surface of the image carrier and the exposure device; and a control unit that controls a rotation operation of the image carrier and determines the amount of wear of at least one of the image carrier and contact members according to at least one of the number of times of start of the rotation operation of the image carrier and the number of times of stop of the rotation operation.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an image forming apparatus and an image forming method for forming an image using an electrophotographic system.

  The present applicant has proposed a method for optimally positioning an optical print head including a light emitting unit including a plurality of light emitting units with respect to a photosensitive drum, and a positioning apparatus for performing the method (see, for example, Patent Document 1). .

JP 2003-11414 A

  By the way, an image forming apparatus including such an optical print head includes a member that wears due to friction with other members in association with repeated printing operations. Such wear can affect image quality.

  Therefore, it is desired to provide an image forming apparatus and an image forming method capable of stably maintaining image quality.

  A first image forming apparatus according to an embodiment of the present invention includes an image carrier including a surface carrying an image, an exposure device that exposes the surface of the image carrier, a surface of the image carrier, and an exposure device. A contact member that abuts both of them and adjusts the distance between the surface of the image carrier and the exposure device, and controls the rotation operation of the image carrier. And a controller that determines the wear amount of at least one of the image carrier and the contact member according to at least one of the above.

  A first image forming method according to an embodiment of the present invention includes starting and stopping a rotation operation of an image carrier including a surface carrying an image, and exposing the surface by an exposure device to perform image formation. The distance between the surface of the image carrier and the exposure device is adjusted in contact with both the surface of the image carrier and the exposure device according to at least one of the number of start and stop times of the rotation operation of the image carrier. Determining the amount of wear of at least one of the contact member and the image carrier.

  In the first image forming apparatus and the first image forming method as one embodiment of the present invention, the image carrier and the contact are made according to at least one of the number of rotations and the number of stops of the rotation operation of the image carrier. Since the wear amount of at least one of the members is obtained, the wear amount of at least one of the image carrier and the abutting member can be estimated more accurately.

  A second image forming apparatus according to an embodiment of the present invention includes an image carrier including a surface carrying an image, an exposure device that exposes the surface of the image carrier, a surface of the image carrier, and an exposure device. A contact member that abuts both of them and adjusts the distance between the surface of the image carrier and the exposure device, and controls the rotation operation of the image carrier. And a control unit that controls at least one of the exposure light amount and the exposure time with respect to the surface by the exposure apparatus according to at least one of

  A second image forming method according to an embodiment of the present invention includes starting and stopping a rotation operation of an image carrier including a surface carrying an image, and exposing the surface by an exposure device to form an image. And controlling at least one of the amount of exposure light and the exposure time for the surface by the exposure device in accordance with at least one of the number of start and stop times of the rotation operation of the image carrier.

  In the second image forming apparatus and the second image forming method as one embodiment of the present invention, the exposure light amount on the surface by the exposure apparatus according to at least one of the number of rotations of the rotation of the image carrier and the number of stops Since at least one of the exposure time and the exposure time is controlled, appropriate exposure is performed.

  A third image forming apparatus according to an embodiment of the present invention includes an image carrier including a surface carrying an image, an exposure device that exposes the surface of the image carrier, a surface of the image carrier, and an exposure device. A contact member that abuts both of them and adjusts the distance between the surface of the image carrier and the exposure device, and controls the rotation operation of the image carrier. And a control unit that determines the replacement timing of at least one of the image carrier and the contact member according to at least one of the above.

  A third image forming method according to an embodiment of the present invention includes starting and stopping a rotation operation of an image carrier including a surface carrying an image, and exposing the surface by an exposure device to form an image. The distance between the surface of the image carrier and the exposure device is adjusted in contact with both the surface of the image carrier and the exposure device according to at least one of the number of start and stop times of the rotation operation of the image carrier. And determining the replacement time of at least one of the contact member and the image carrier.

  In the third image forming apparatus and the third image forming method as one embodiment of the present invention, the control unit controls the image carrier and the image carrier according to at least one of the number of rotations and the number of stops of the rotation of the image carrier. Since the replacement time of at least one of the contact members is obtained, the life of the image carrier and the contact member can be judged more accurately.

  According to the image forming apparatus and the image forming method as one embodiment of the present invention, the image quality can be stably maintained. In addition, the effect of this invention is not limited to this, Any effect described below may be sufficient.

1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a configuration example of a main part of an image forming unit mounted on the image forming apparatus illustrated in FIG. 1. FIG. 3 is a schematic diagram illustrating a configuration example of an exposure head of the image forming unit illustrated in FIG. 2 and its periphery. FIG. 2 is a block diagram schematically illustrating a configuration example of a control mechanism of the image forming apparatus illustrated in FIG. 1. It is a conceptual diagram showing the rotational speed of the photosensitive drum at the time of printing operation, and the frictional force between the photosensitive drum and the interval adjusting member. FIG. 3 is a characteristic diagram illustrating a relationship between a print duty and a print density of an image printed by the image forming apparatus illustrated in FIG. 1. FIG. 10 is another characteristic diagram illustrating the relationship between the print duty and the print density of an image printed in the image forming apparatus illustrated in FIG. 1. 3 is a flowchart illustrating an operation example of the image forming apparatus illustrated in FIG. 1.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The following description is an example of the present invention, and the present invention is not limited to the following embodiment. Further, the present invention is not limited to the arrangement, dimensions, dimensional ratios, and the like of the components shown in the drawings. The description will be made in the following order.
1. Embodiment 1 Example of Changing Initially Set Exposure Light Amount and Exposure Time Based on Number of Starts of Printing Modified example

<1. Embodiment>
[1.1 Configuration of Image Forming Apparatus 10]
FIG. 1 is a schematic diagram illustrating an example of the overall configuration of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 is an electrophotographic printer that forms an image (for example, a monochrome image) on a medium (also referred to as a print medium or a transfer material) 300 such as paper.

  As shown in FIG. 1, the image forming apparatus 10 includes a paper feed tray 200 that accommodates a medium 300, a pickup roller 400, a transfer device 800, a fixing device 600, in addition to the image forming unit 100, in a housing 1000. A carry-out roller pair 700 and a temperature / humidity sensor 900 are provided.

  The paper feed tray 200 is a member that stores the medium 300 in a stacked state, and is detachably attached to the lower portion of the image forming apparatus 10, for example.

  The pick-up roller 400 is a member that takes out the medium 300 stored in the paper feed tray 200 one by one from the top and feeds it onto the transport path 500.

  The image forming unit 100 develops a toner image on the medium 300 conveyed on the conveyance path 500. The image forming unit 100 includes a toner cartridge 101 that contains toner T, and an image forming cartridge 102 that forms an image using toner T that is located below the toner cartridge 101 and is supplied from the toner cartridge 101.

  The transfer device 800 is a device for electrostatically transferring the toner image developed in the image forming unit 100 onto the surface of the medium 300. The transfer device 800 includes, for example, a transfer belt 801, a driving roller 802, a driven roller 803, and a transfer roller 7. The transfer belt 801 has a function of conveying the medium 300. The driving roller 802 is a member that circulates and rotates the transfer belt 801. The driven roller 803 follows the circulation rotation of the transfer belt 801 and stretches the transfer belt 801 in cooperation with the driving roller 802. The transfer roller 7 is disposed so as to face the photosensitive drum 1 with the transfer belt 801 interposed therebetween. The transfer belt 801 is provided with an elastic layer made of a material having a lower hardness and a protective layer made of a fluororesin (for example, polytetrafluoroethylene) on a base made of, for example, polyimide, PVDF, or urethane. It is preferable to have a multilayer structure.

  The fixing device 600 is a mechanism for fixing the toner image onto the medium 300 by applying heat and pressure to the toner image transferred onto the medium 300.

  The carry-out roller pair 700 is a member that conveys the medium 300 on which the toner is fixed by the fixing device 600 in a direction indicated by an arrow in FIG. 2 and discharges the medium 300 to a discharge tray outside the housing 1000.

[1.2 Configuration of Image Forming Unit 100]
FIG. 2 is a schematic diagram illustrating a schematic configuration example of the image forming cartridge 102 and its periphery in the image forming unit 100 according to the embodiment of the present invention. The image forming unit 100 forms a toner image by using the toner T accommodated in the toner cartridge 101 shown in FIG. In this specification, the direction in which the medium 300 travels is referred to as a transport direction, and a direction perpendicular to the transport direction, which is perpendicular to the paper surface of FIG. 1, is referred to as a lateral direction, a width direction, or a main scanning direction.

  The toner T is composed of, for example, a nonmagnetic material including a binder resin such as a polyester resin, a charge control agent as an internal additive, a release agent, and a colorant, and an external additive such as silica and titanium oxide. It is what is done. Among these, the color of the toner image formed by the image forming unit 100 can be changed by appropriately selecting the color of the colorant.

  As shown in FIG. 2, the image forming cartridge 102 includes a photosensitive drum 1, a charging roller 2, a developing roller 4, a supply roller 5, a toner regulating member 6, and a cleaning member 8.

  The photosensitive drum 1 is a columnar member extending in the lateral direction, and is configured using a photosensitive member (for example, an organic photosensitive member). The photosensitive drum 1 functions as an electrostatic latent image carrier that carries an electrostatic latent image on its surface (surface layer portion) 1S. Specifically, the photosensitive drum 1 is formed by sequentially stacking a charge generation layer and a charge transport layer as a photoconductive layer so as to cover an outer peripheral surface of a metal pipe (conductive support) made of, for example, aluminum. It is. The photosensitive drum 1 is rotated at a predetermined peripheral speed, for example, in a rotation direction 1R (clockwise on the paper surface) indicated by an arrow by a rotation driving unit 40 (described later) controlled by the drive control unit 24 (described later). It has become. The photosensitive drum 1 corresponds to a specific example of “image carrier” of the invention.

  The charging roller 2 is a member (charging member) that charges the surface 1 </ b> S of the photosensitive drum 1, and is disposed so as to contact the surface 1 </ b> S of the photosensitive drum 1. The charging roller 2 has, for example, a metal shaft and a semiconductive rubber layer (for example, a semiconductive epichlorohydrin rubber layer) covering the outer periphery (surface) thereof. The charging roller 2 is rotated at a predetermined peripheral speed (rotated in the opposite direction to the photosensitive drum 1) by a rotation driving unit 40 controlled by the drive control unit 24. A charging voltage is applied to the charging roller 2 by a charging roller voltage power source 2V.

  The developing roller 4 is a member that carries a toner T for developing an electrostatic latent image on the surface thereof, and is disposed so as to be in contact with the surface 1S of the photosensitive drum 1. The developing roller 4 has, for example, a metal shaft and a semiconductive urethane rubber layer covering the outer peripheral surface (surface) thereof. The developing roller 4 is rotated at a predetermined peripheral speed (rotated in the same direction as the photosensitive drum 1) by a rotation driving unit 40 controlled by the drive control unit 24. Further, a developing voltage is applied to the developing roller 4 by a developing roller voltage power source 4V.

  The supply roller 5 is a member (supply member) for supplying the toner T to the developing roller 4 and is disposed so as to be in contact with the surface of the developing roller 4. The supply roller 5 has, for example, a metal shaft and a foamable silicone rubber layer that covers the outer periphery (surface) of the metal shaft. The supply roller 5 is rotated at a predetermined peripheral speed (rotated in the same direction as the developing roller 4) by a rotation driving unit 40 controlled by the drive control unit 24. A supply voltage is applied to the supply roller 5 by a supply roller voltage power supply 5V.

  The toner regulating member 6 forms a layer (toner layer) made of toner T on the surface of the rotating developing roller 4 and regulates (controls and adjusts) the thickness of the toner layer. The toner regulating member 6 is a plate-like elastic member (plate spring) made of, for example, stainless steel, and is disposed so that the bent portion in the vicinity of the tip of the plate-like elastic member slightly contacts the surface of the developing roller 4. .

  The cleaning member 8 is a member that cleans the surface 1S of the photosensitive drum 1 by scraping and collecting the toner T remaining on the surface 1S of the photosensitive drum 1. The cleaning member 8 is arranged so as to come into contact with the surface 1S by a counter (contact in the opposite direction to the rotation direction 1R of the photosensitive drum 1). Such a cleaning member 8 is comprised by elastic bodies, such as a polyurethane rubber, for example.

  On the outside of the image forming cartridge 102, an exposure head 3 and a transfer roller 7 facing the photosensitive drum 1 are provided.

  The exposure head 3 is an apparatus that forms an electrostatic latent image on the surface 1S of the photoconductive drum 1 by exposing the surface 1S of the photoconductive drum 1 that is opposed at a predetermined interval. The exposure head 3 extends in the horizontal direction with a light emitting element array 3B2 (described later) composed of a plurality of light emitting elements that are arranged in the horizontal direction (main scanning direction) with respect to one photosensitive drum 1 and emits irradiation light. In addition, a rod lens array 3D (described later) for forming an image of the irradiation light from the plurality of light emitting elements on the surface 1S of the photosensitive drum 1 is provided. The light emitting element includes, for example, an LED (Light Emitting Diode). The operation of the exposure head 3 is controlled by an exposure control unit 25 (described later).

  The transfer roller 7 is rotated at a predetermined peripheral speed (rotated in the opposite direction to the photosensitive drum 1) by a rotation driving unit 40 controlled by the drive control unit 24. A transfer voltage is applied to the transfer roller 7 by a transfer roller voltage power supply 7V. The transfer roller 7 is a member that, as it rotates, conveys the medium 300 while conveying it downstream, and electrostatically transfers the toner image formed on the image forming cartridge 102 onto the medium 300. The transfer roller 7 has, for example, a metal shaft and a semiconductive urethane rubber layer that covers the outer peripheral surface (surface) thereof.

[1.3 Configuration of exposure head 3 and its surroundings]
FIG. 3 is a schematic diagram showing a schematic configuration example of the exposure head 3 and its periphery in the image forming unit 100 according to the embodiment of the present invention. The right view of FIG. 3 is a front view of the exposure head 3 as viewed from the transport direction, and the center view of FIG. 3 is a side view of the exposure head 3 as viewed laterally. This figure is a cross-sectional view orthogonal to the horizontal direction. As shown in FIG. 3, the exposure head 3 includes a print head 3A and a distance adjusting member 9 (an eccentric roller 3G and an abutting piece 3H) provided between the print head 3A and the surface 1S of the photosensitive drum 1. And have. Here, the print head 3A is one specific example corresponding to the “exposure apparatus” of the present invention.

  The print head 3A extends in the lateral direction so as to face the photosensitive drum 1, and includes a light emitting element array unit 3B, a base 3C, a rod lens array 3D, and a rod lens array holder 3E. The light emitting element array unit 3B includes, for example, a substrate 3B1 extending in the horizontal direction and a light emitting element array 3B2 including a plurality of light emitting elements arranged in the horizontal direction (X-axis direction) on the substrate 3B1. The base 3C is a support that supports the light emitting element array unit 3B. The rod lens array 3D is an optical member that forms an image on the surface 1S of the photosensitive drum 1 while transmitting light from the light emitting element array unit 3B. The rod lens array holder 3E holds the base 3C and the rod lens array 3D so that the distance between the rod lens array 3D and the light emitting element array 3B2 supported by the base 3C is appropriate.

The interval adjusting member 9 has an eccentric roller 3G and an abutment piece 3H, and is provided in the vicinity of both ends in the lateral direction of the print head 3A. The eccentric roller 3G is a member that adjusts the distance L between the rod lens array 3D and the surface 1S of the photosensitive drum 1 by itself rotating around the rotation axis J3G. The abutting piece 3H is a pedestal that rotatably supports the eccentric roller 3G, and a part thereof is in contact with the surface 1S of the photosensitive drum 1. The exposure head 3 is constantly biased with respect to the photosensitive drum 1 by a biasing member (not shown) such as a coil spring. The abutting piece 3H slides on the surface 1S when the photosensitive drum 1 rotates. Thus, the eccentric roller 3G and the abutting piece 3H are one specific example corresponding to the “contact member” of the present invention, and the distance L between the rod lens array 3D and the surface 1S of the photosensitive drum 1 is appropriately set. It functions as the interval adjusting member 9 to be held.
However, when the printing operation is repeated, friction between the photosensitive drum 1 and the abutting piece 3H occurs, and at least one of the photosensitive drum 1 and the abutting piece 3H is worn. Therefore, as will be described later, in the present embodiment, exposure control in the exposure head 3 is performed in accordance with the wear amount of at least one of the photosensitive drum 1 and the abutting piece 3H.

[1.4 Control Mechanism of Image Forming Apparatus 10]
Next, a control mechanism of the image forming apparatus 10 will be described mainly with reference to FIG. FIG. 4 is a block diagram illustrating an example of a control mechanism of the image forming apparatus 10 illustrated in FIG. As shown in FIG. 4, the image forming apparatus 10 includes a control unit 20, a high-voltage power supply unit 30, and a rotation drive unit 40 as its control mechanism.

  The control unit 20 includes a storage unit 21, an arithmetic processing unit 22, a voltage control unit 23, a drive control unit 24, an exposure control unit 25, an interface (I / F) control unit 26, and a sensor group 27.

  The control unit 20 is a specific example corresponding to the “control unit” of the present invention. The control unit 20 controls the rotational operation of the photosensitive drum 1 and the cumulative number of times the rotational operation of the photosensitive drum 1 is started under an arbitrary condition. The amount of wear Pw (described later) of at least one of the photosensitive drum 1 and the interval adjusting member 9 is obtained in accordance with (the number of times of starting cumulative rotation described later) Ps. Further, the control unit 20 controls at least one of the exposure light amount and the exposure time with respect to the surface 1S of the photosensitive drum 1 by the exposure head 3 in accordance with the cumulative number of rotations of the rotating operation of the photosensitive drum 1 under an arbitrary condition. To do. Further, the control unit 20 obtains the replacement time of at least one of the photosensitive drum 1 and the interval adjusting member 9 according to the cumulative number of rotations of the rotating operation of the photosensitive drum 1.

  The storage unit 21 is composed of a semiconductor memory such as a ROM or a RAM that stores a sequence control program for a printing operation, various data for controlling the image forming apparatus 10 and various specified values for comparison.

  The arithmetic processing unit 22 is a microprocessor that performs arithmetic processing for operating the image forming apparatus 10 based on various data from the storage unit 21 and other data. More specifically, the arithmetic processing unit 22 includes a time measuring device (timer) 2A, a rotation number counter 2B, a rotation start number counter 2C, and a wear amount calculation unit 2D. The timer 2A is used to synchronize the control timing of various printing operations. The rotation number counter 2 </ b> B counts the number of rotations of the photosensitive drum 1. The rotation start number counter 2 </ b> C counts the number of rotations of the photosensitive drum 1 (the total number of rotations of the rotation of the photosensitive drum 1). The wear amount calculation unit 2D calculates the wear amount of the surface 1S of the photosensitive drum 1 and the abutting piece 3H.

  The voltage control unit 23 receives the calculation processing result from the calculation processing unit 22, and sets the voltage output value to the charging roller 2, the developing roller 4, the supply roller 5, and the transfer roller 7 and performs on / off control of the voltage output. Is.

The drive control unit 24 performs on / off control of the driving force of the rotation driving unit 40.
The exposure control unit 25 performs on / off control in dot units for a plurality of light emitting elements arranged in dot units in the exposure head 3.

  The I / F control unit 26 receives print data and control commands from a host device such as a personal computer (PC), and transmits them to the arithmetic processing unit 22.

  The sensor group 27 includes various sensors that monitor the operation state of the image forming apparatus 10, such as a position detection sensor for the medium 300, a temperature / humidity sensor 900, a print density sensor, and a toner remaining amount detection sensor.

  The high-voltage power supply unit 30 includes a voltage output unit 31 that applies appropriate voltages to the charging roller 2, the developing roller 4, the supply roller 5, and the transfer roller 7. The high-voltage power supply unit 30 applies the voltage output unit 31 to each of the various constituent members (the charging roller 2, the developing roller 4, the supply roller 5, and the transfer roller 7) based on an instruction from the voltage control unit 23 in the control unit 20. Control the voltage. The voltage output unit 31 includes a charging roller voltage power source 2V, a developing roller voltage power source 4V, a supply roller voltage power source 5V, and a transfer roller voltage power source 7V. The voltage control unit 23 controls, for example, at least one of the exposure light amount and the exposure time with respect to the surface 1S by the exposure head 3 according to the wear amount of the butting piece 3H calculated by the wear amount calculation unit 2D in the calculation processing unit 22. To do. Alternatively, the voltage control unit 23 selects a friction coefficient between the photosensitive drum 1 and the interval adjusting member 9 according to the environmental temperature and the environmental humidity measured by the temperature / humidity sensor 900 included in the sensor group 27, The wear amount of the butting piece 3H calculated by the wear amount calculation unit 2D may be corrected.

  The rotation drive unit 40 applies a driving force to each rotation member and each conveyance member, and includes, for example, electronic components such as a DC motor and a pulse motor, and peripheral gears.

[1.5 Actions and effects]
(A. Basic operation)
In the image forming apparatus 10, a toner image is formed on the medium 300 as follows.

  When print image data and a print command are input to the arithmetic processing unit 22 from an external device such as a PC via the I / F control unit 26 to the activated image forming apparatus, the arithmetic processing unit 22 outputs the print command. In response, the printing operation of the print image data is started in cooperation with the drive control unit 24 or the like.

  The drive control unit 24 drives the rotation driving unit 40 to rotate the photosensitive drum 1 at a constant speed in the rotation direction 1R as shown in FIG. When the photosensitive drum 1 rotates, the power is transmitted to the supply roller 5, the developing roller 4 and the charging roller 2 via a drive transmission mechanism such as a gear train. As a result, the supply roller 5, the developing roller 4, and the charging roller 2 are each rotated in a predetermined direction.

  Next, the high voltage power supply unit 30 applies a predetermined charging voltage from the charging roller voltage power supply 2V to the charging roller 2 based on the control of the voltage control unit 23 to uniformly charge the surface 1S of the photosensitive drum 1. .

  Next, the exposure control unit 25 activates the exposure head 3 to irradiate the photosensitive drum 1 with light corresponding to the color component (here, black) of the printed image based on the image signal, so that the surface 1S of the photosensitive drum 1 is statically irradiated. An electrostatic latent image is formed. Further, in the image forming unit 100, the toner T is developed on the electrostatic latent image formed on the surface 1S of the photosensitive drum 1 as follows.

  Specifically, first, the toner T is put into the image forming cartridge 102 from the toner cartridge 101. The toner T is carried on the supply roller 5 and moves to the vicinity of the developing roller 4 by the rotation of the supply roller 5. At this time, the toner T is supplied to the developing roller 4, for example, negatively charged due to friction between the developing roller 4 and the supply roller 5 and due to a potential difference between the potential of the developing roller 4 and the potential of the supply roller 5. The toner T supplied to the developing roller 4 forms a toner layer regulated to a predetermined thickness by the toner regulating member 6. Thereafter, the toner layer on the developing roller 4 is developed with respect to the electrostatic latent image formed on the surface 1S of the photosensitive drum 1 as described above, so that the toner image is formed on the surface 1S of the photosensitive drum 1. It is formed.

  On the other hand, the drive control unit 24 drives the rotation driving unit 40, and the transfer device 800 starts conveying the medium 300. With this conveyance control, the medium 300 is conveyed at a predetermined conveyance speed to a transfer unit where the photosensitive drum 1 and the transfer roller 7 face each other. Specifically, as shown in FIG. 1, first, the medium 300 stored in the paper feed tray 200 is picked up one by one from the uppermost portion by the pickup roller 400 and fed out to the transport path 500. The medium 300 fed out by the pickup roller 400 is conveyed to the transfer unit by the transfer belt 801.

  A predetermined transfer voltage is applied to the transfer roller 7 provided facing the photosensitive drum 1 by a transfer roller voltage power source 7V in accordance with the timing of conveying the medium 300 to the transfer unit. As a result, the toner image formed on the photosensitive drum 1 is transferred onto the surface of the medium 300 traveling on the conveyance path 500 between the photosensitive drum 1 and the transfer roller 7.

  Thereafter, the fixing device 600 applies heat and pressure to the toner image transferred onto the medium 300 to fix the toner image on the medium 300. After that, the medium 300 on which the toner image is fixed is discharged to a discharge tray outside the housing 1000 by the carry-out roller pair 700. The toner T that has not been transferred to the medium 300 may remain slightly on the photosensitive drum 1, but the remaining toner T is removed by the cleaning member 8. For this reason, the photosensitive drum 1 can be used continuously.

(B: Method for calculating the wear amount of the butting piece 3H)
Next, with reference to FIG. 5, a method for calculating the wear amount of the abutment piece 3H by the wear amount calculation unit 2D will be described. 5A is a conceptual diagram illustrating the rotational speed S of the photosensitive drum 1 during the printing operation in the image forming apparatus 10, where the horizontal axis represents time T and the vertical axis represents the rotational speed S. Yes. 5B is a conceptual diagram illustrating the frictional force F generated between the photosensitive drum 1 and the abutting piece 3H during the printing operation in the image forming apparatus 10, and the horizontal axis represents the time T. The vertical axis represents the frictional force F.

  In the example of the printing operation shown in FIG. 5, the printing operation is started at time T = t0. That is, as shown in FIG. 5A, the rotational speed S of the photosensitive drum 1 starts to rise from S = s0 at time T = t0, and immediately after that, until time T = t2, S = Stabilizes at s1. At this time, as shown in FIG. 5B, immediately after the change of the rotational speed S is started, the frictional force caused by the static friction coefficient μ0 is between the photosensitive drum 1 and the abutting piece 3H. f0 is generated. After that, the frictional force f1 due to the dynamic friction coefficient μ1 is immediately generated at time T = t1, and the frictional force f1 is also maintained while the rotational speed S = s1 is maintained (until time T = t2). The

  Here, the total wear amount Pw of the photosensitive drum 1 and the abutting piece 3H accompanying the printing operation is equal to the wear amount depending on the accumulated rotational speed of the photosensitive drum 1 during the printing operation, and the photosensitive drum during the printing operation. It can be thought of as the sum of the wear amount depending on the accumulated number of rotations of 1 (the accumulated number of rotations of the rotation operation). Therefore, the wear amount Pw is obtained by the following conditional expression (1).

Pw = A * (μenv / μ) * Pn + B * (μ0env / μ0) * Ps (1)

  In conditional expression (1), the first term on the right side represents the amount of wear depending on the accumulated number of rotations of the photosensitive drum 1, and the second term on the right side represents the amount of wear depending on the number of accumulated rotations of the photosensitive drum 1. Yes. A and B are coefficients. μenv is a dynamic friction coefficient at the environmental temperature and environmental humidity during the printing operation, and μ is a dynamic friction coefficient at the reference environmental temperature and environmental humidity. μ0env is a coefficient of static friction at the environmental temperature and environmental humidity during the printing operation, and μ0 is a coefficient of static friction at the environmental temperature and humidity as the environmental standard. Pn is the cumulative rotation number of the photosensitive drum 1 during the printing operation, and Ps is the cumulative rotation start number of the photosensitive drum 1 during the printing operation.

  The wear amount calculation unit 2D calculates the wear amount Pw based on, for example, various pieces of information stored in the storage unit 21, that is, the dynamic friction coefficients μenv, μ, the static friction coefficients μ0env, μ0, the accumulated rotation number Pn, and the accumulated rotation start number Ps. calculate.

(C: Exposure control according to wear amount Pw)
Next, exposure control according to the wear amount Pw calculated based on the conditional expression (1) will be described. 6 and 7 are characteristic diagrams showing the relationship between the print duty and the print density of an image printed by the image forming apparatus 10. Note that the print duty, which is the horizontal axis in FIG. 6 and FIG. 7, is the thinning of the exposure dots evenly compared to the case where the entire medium 300 (for example, A4 size paper) is filled with exposure dots, so-called solid printing is 100%. The ratio of the exposed dot area when actually printed so as to be filled in. The print density on the vertical axis in FIGS. 6 and 7 indicates the density of the toner image printed on the medium 300, as a spectral densitometer “X-Rite 528” (C light source, viewing angle 2 °) manufactured by X-Rite. The value measured by means of a relative value. The higher the numerical value, the darker the print density.

  FIG. 6 particularly shows the influence of the amount of deviation dL on the print density. The shift amount dL is a difference between the focal length of the rod lens array 3D and the distance L (interval between the rod lens array 3D and the surface 1S of the photosensitive drum 1) shown in FIG. That is, it can be said that the error is between the set value and the actually measured value. At the beginning of manufacture (before use), the deviation dL between the design value and the actual measurement value is substantially zero, but the deviation dL between the design value and the actual measurement value tends to increase by repeatedly performing the printing operation. Specifically, when the printing operation is repeated, the focal length of the rod lens array 3D is basically unchanged, while the wear amount Pw of the photosensitive drum 1 and the abutting piece 3H is equal to the accumulated rotational speed Pn and It increases as the cumulative rotation start count Ps increases. Therefore, as the wear amount Pw increases, the shift amount dL also increases. This is because the distance L between the rod lens array 3 </ b> D and the surface 1 </ b> S of the photosensitive drum 1 is shortened by increasing the wear amount Pw. As shown in FIG. 6, it is recognized that the print density tends to increase as the wear of the photosensitive drum 1 and the abutting piece 3H progresses and the shift amount dL increases. This is because as the distance L deviates from the focal length of the rod lens array 3D, that is, the closer the rod lens array 3D and the surface 1S of the photosensitive drum 1 are (0 μm → 45 μm → 90 μm), the surface 1S of the photosensitive drum 1 is increased. This is because the spot diameter of the light applied to the light beam increases.

  FIG. 7 particularly shows the influence of the amount of light applied to the surface 1S on the print density. As shown in FIG. 7, it is recognized that the print density tends to increase as the amount of light applied to the surface 1S increases.

  From the results of FIGS. 6 and 7, by repeatedly performing the printing operation, the wear amount Pw of the photosensitive drum 1 and the abutting piece 3H is increased, and the surface 1S by the exposure head 3 is increased as the shift amount dL increases. It can be said that fluctuations in the print density can be suppressed by reducing (decreasing) the amount of light irradiated to.

  Specifically, the wear amount Pw of the photosensitive drum 1 and the abutting piece 3H is obtained based on the above-described formula (1). Next, for example, using a light amount correction coefficient C (for example, see Table 1) set in advance based on experimental data, a corrected exposure light amount W1 corresponding to the wear amount Pw is calculated by the following equation (2). In Expression (2), W is a reference exposure light amount W0 before the start of use (when the wear amount Pw = 0).

W1 = f (Pw) * W = C * Pw (2)

  The exposure control unit 25 controls the exposure head 3 so that the corrected exposure light amount W1 obtained by the equation (2) is obtained. Thereby, the change of the printing density resulting from the increase in the wear amount Pw can be suppressed, and a stable printing operation can be performed.

  The amount of wear Pw was about 20 to 30 [mu] m when 5000 sheets of A4 size paper were printed side by side (conveying with the short side direction as the conveying direction), one sheet per job. The result and the results of FIGS. 6 and 7 were combined to obtain the light amount correction coefficient C shown in Table 1. In Table 1, the wear amount Pw is divided every 5 μm and the light amount correction coefficient C suitable for each division is set. However, the present invention is not limited to this. For example, the light amount correction coefficient C uniquely determined with respect to the wear amount Pw may be obtained by a calculation formula or the like. The numerical values shown in Table 1 are merely examples, and can be appropriately changed depending on various conditions such as the material of the photosensitive drum 1 and the abutting piece 3H. Furthermore, although the case where the exposure light amount is changed is described here as an example of exposure control according to the wear amount Pw, the exposure control unit 25 may change the exposure time according to the wear amount Pw. For example, an increase in print density can be suppressed by shortening the exposure time for the surface 1S of the exposure head 3 while maintaining the exposure light amount on the surface 1S. Further, the exposure control unit 25 may control both the exposure light amount and the exposure time of the exposure head 3 according to the wear amount Pw.

  FIG. 8 is a flowchart showing the procedure of exposure control performed in accordance with the amount of wear of the abutting piece 3H in the image forming apparatus 10.

  As illustrated in FIG. 8, the control unit 20 acquires the environmental temperature and the environmental humidity during the printing operation using the temperature / humidity sensor included in the sensor group 27 (step S <b> 101).

  Next, the static friction coefficient μ0env and the dynamic friction coefficient μenv corresponding to the environmental temperature and environmental humidity detected in step S101 are read from the storage unit 21 (step S102).

  After that, it is determined whether or not the current printing operation is the first operation (step S103). If it is the first operation (step S103Y), the printing operation is started (step S104). On the other hand, if it is not the first operation (step S103N), the wear amount Pw at the end of the previous printing operation is read from the storage unit 21 (step S105), the corrected exposure light amount W1 is determined (step S106), and then the corrected exposure is performed. A printing operation is started under image forming conditions using the light amount W1 or the like (step S104). The corrected exposure light amount W1 is given by, for example, equation (2).

  After that, while repeating the printing operation, the control unit 20 counts the number of rotations of the photosensitive drum 1 and the number of rotations of the photosensitive drum 1, respectively, to obtain the total number of rotations Pn and the total number of rotations Ps (step S107). Then, the wear amount calculation unit 2D sequentially calculates the wear amount Pw (step S108).

  The controller 20 determines whether the wear amount Pw is within a preset allowable range (step S109). When the wear amount Pw is within the allowable range (step S109Y), the control unit 20 determines whether print data remains (step S110). If print data remains (step S110Y), the printing operation is started again (step S104). If no print data remains (step S110N), the printing operation is ended (step S111), and the finally calculated wear amount Pw at the end of printing is stored in the storage unit 21 (step S112), and then the processing ends (step S112). End).

  On the other hand, when the wear amount Pw is out of the allowable range (step S109N), the printing operation is stopped, a warning is issued (step S113), and the process ends (end).

(D: Effect)
As described above, in the image forming apparatus 10 of the present embodiment, the total wear amount Pw of the photosensitive drum 1 and the abutting piece 3H is obtained according to the cumulative rotation start number Ps of the photosensitive drum 1. The wear amount Pw can be estimated more accurately. Therefore, the image forming apparatus 10 can stably maintain the image quality. This is because, based on the accurately estimated wear amount Pw, the exposure head 3 can expose the surface 1S of the photosensitive drum 1 with an appropriate corrected exposure light amount W1 each time. That is, when the photosensitive drum 1 and the abutting piece 3H are worn due to repeated printing operations over a long period of time, the distance L between the surface 1S of the photosensitive drum 1 and the rod lens array 3D is reduced from the initial value. Even so, image formation can be performed under image forming conditions suitable for the reduced distance L as appropriate. Therefore, it is possible to maintain a stable image quality with little fluctuations in print density and the like over a long period of time.

  In addition, since the wear amount Pw can be estimated more accurately in the image forming apparatus 10, for example, the life of the photosensitive drum 1 and the abutting piece 3H can be accurately predicted, and an appropriate replacement time can be obtained. For this reason, before the image defect occurs, the photosensitive drum 1 and the abutting piece 3H can be replaced at an appropriate timing, and image formation with good quality can be continuously performed.

<2. Modification>
Although the present invention has been described with reference to the embodiments and examples, the present invention is not limited to these embodiments and the like, and various modifications are possible. For example, in the above-described embodiment, an image forming apparatus that forms a monochrome image has been described. However, the present invention is not limited to this, and may be an image forming apparatus that forms a color image, for example. In the above embodiment, the direct transfer type image forming apparatus 10 has been described. However, the present invention can also be applied to a secondary transfer type.

  Further, the series of processes described in the above embodiments may be performed by hardware (circuit) or may be performed by software (program). When performed by software, the software is composed of a group of programs for causing each function to be executed by a computer. Each program may be used by being incorporated in advance in the computer, for example, or may be used by being installed in the computer from a network or a recording medium.

  In the above embodiment, the LED head using a light emitting diode as a light source is used as the exposure device. However, for example, an exposure device using a laser element or the like as a light source may be used.

  Furthermore, in the above embodiment, an image forming apparatus having a printing function has been described as a specific example of the “image forming apparatus” in the present invention. However, the present invention is not limited to this. That is, in addition to such a printing function, for example, the present invention can also be applied to an image forming apparatus that functions as a multifunction peripheral having a scanning function and a fax function.

  In the above embodiment, the exposure control unit 25 appropriately controls the exposure light amount and the exposure time in the exposure head 3 to stabilize the image quality, but the present invention is not limited to this. In the present invention, any control unit may be used as long as the image forming condition is changed in accordance with the wear amount of the contact member obtained in accordance with the cumulative number of times of starting the image carrier. That is, the image forming conditions are not limited to the voltage applied to the exposure head 3 or the exposure time by the exposure head 3. The image carrier tends to be more easily charged as the photosensitive layer on the surface thereof is worn. Therefore, the absolute value of the developing voltage applied to the developer carrying member (developing roller 4) is preferably reduced as the number of times the image carrier is started up. By doing so, the amount of toner per dot can be reduced, and an increase in print density due to wear of the photosensitive layer can be suppressed.

  In the above-described embodiment, the total wear amount Pw of the photosensitive drum 1 and the abutting piece 3H is obtained according to the cumulative number of rotations of the rotational operation of the photosensitive drum 1 (integrated rotation start number) Ps. The present invention is not limited to this. For example, the wear amount of only the photosensitive drum 1 or the wear amount of only the butting piece 3H may be obtained. Further, the replacement timing of at least one of the photosensitive drum 1 and the abutting member is directly determined without obtaining the wear amount Pw according to the cumulative number of rotations of the rotational operation of the photosensitive drum 1 (integrated rotation start number) Ps. You may make it ask. In that case, the replacement time may be obtained in consideration of the integrated rotational speed of the photosensitive drum 1. Furthermore, it is also possible to control at least one of the exposure light amount and the exposure time of the exposure head 3 without obtaining the wear amount according to the cumulative number of times of rotation start of the photosensitive drum 1 (total number of rotation start times) Ps. Good. Also in that case, at least one of the exposure light amount and the exposure time of the exposure head 3 may be controlled in consideration of the integrated rotational speed of the photosensitive drum 1.

  In the above-described embodiment, the wear amount calculation unit 2D sequentially calculates the wear amount Pw each time the accumulated rotation number Pn and the accumulated rotation start number Ps of the photosensitive drum 1 are acquired. However, the calculation amount is reduced. For example, the wear amount Pw may be calculated every time the printing operation is started.

  Further, according to the present invention, the controller controls the exposure apparatus and the contact member other than the wear amount, the voltage, or the life according to at least one of the cumulative start count and the total stop count of the rotation operation of the image carrier. Another physical quantity related to at least one of them may be obtained.

  Further, in the above embodiment, the wear amount is estimated, the voltage is controlled, or the replacement time is determined according to the number of times of starting the image carrier integration under an arbitrary condition. It is not limited. For example, wear amount estimation, voltage control, or replacement timing may be determined according to the number of stoppages of integration of the image carrier. Alternatively, estimation of wear amount, voltage control, or determination of replacement time may be performed in accordance with both the number of start times of integration and the number of stop times of integration.

  DESCRIPTION OF SYMBOLS 1 ... Photosensitive drum, 1S ... Surface, 2 ... Charging roller, 3 ... Exposure head, 3A ... Print head, 3B ... Light emitting element array unit, 3C ... Base, 3D ... Rod lens array, 3E ... Rod lens array holder, 3G ... Eccentric roller, 3H ... Abutting piece, 4 ... Developing roller, 5 ... Supply roller, 6 ... Toner regulating member, 7 ... Transfer roller, 8 ... Cleaning member, 9 ... Interval adjusting member, 10 ... Image forming apparatus, 20 ... Control unit, 21 ... storage unit, 22 ... arithmetic processing unit, 2A ... time measuring device (timer), 2B ... rotation number counter, 2C ... rotation start number counter, 2D ... wear amount calculation unit, 23 ... voltage control unit, 24 DESCRIPTION OF SYMBOLS ... Drive control part, 25 ... Exposure control part, 26 ... I / F control part, 27 ... Sensor group, 30 ... High voltage power supply part, 31 ... Voltage output part, 40 ... Rotation drive part, 2V ... Charging roller voltage power supply, 4 ... Development roller voltage power supply, 5V ... Supply roller voltage power supply, 7V ... Transfer roller voltage power supply, 100 ... Image forming unit, 101 ... Toner cartridge, 102 ... Image forming cartridge, 200 ... Paper feed tray, 300 ... Medium, 400 ... Pickup Roller, 500 ... conveying path, 600 ... fixing device, 700 ... unloading roller pair, 800 ... transfer device, 900 ... temperature and humidity sensor, 1000 ... housing.

Claims (12)

An image carrier comprising a surface carrying an image;
An exposure apparatus that exposes the surface of the image carrier;
An abutting member that abuts both the surface of the image carrier and the exposure apparatus, and adjusts a distance between the surface of the image carrier and the exposure apparatus;
The rotation amount of the image carrier is controlled, and the amount of wear of at least one of the image carrier and the contact member according to at least one of the number of start and stop times of the rotation of the image carrier An image forming apparatus comprising: The image forming apparatus according to claim 1, wherein the control unit obtains the wear amount in consideration of a rotational speed of the image carrier. A sensor for measuring at least one of environmental temperature and environmental humidity;
The control unit selects a friction coefficient between the image carrier and the contact member according to at least one of the environmental temperature and the environmental humidity, and corrects the wear amount. The image forming apparatus according to claim 2. 4. The image forming apparatus according to claim 1, wherein the control unit changes an image forming condition based on the amount of wear determined according to at least one of the number of times of starting and the number of times of stopping. 5. . An image carrier comprising a surface carrying an image;
An exposure apparatus that exposes the surface of the image carrier;
An abutting member that abuts both the surface of the image carrier and the exposure apparatus, and adjusts a distance between the surface of the image carrier and the exposure apparatus;
The rotation operation of the image carrier is controlled, and at least one of the exposure light amount and the exposure time with respect to the surface by the exposure device is controlled according to at least one of the start frequency and the stop frequency of the rotation operation of the image carrier. An image forming apparatus. The image forming apparatus according to claim 5, wherein the control unit controls at least one of the exposure light amount and the exposure time in consideration of a rotation speed of the image carrier. An image carrier comprising a surface carrying an image;
An exposure apparatus that exposes the surface of the image carrier;
An abutting member that abuts both the surface of the image carrier and the exposure apparatus, and adjusts a distance between the surface of the image carrier and the exposure apparatus;
A timing for exchanging at least one of the image carrier and the abutting member according to at least one of the number of start and stop times of the rotation of the image carrier while controlling the rotation of the image carrier. An image forming apparatus comprising: The image forming apparatus according to claim 7, wherein the control unit obtains the replacement time in consideration of a rotation speed of the image carrier. An image carrier comprising a surface carrying an image;
An exposure apparatus that exposes the surface of the image carrier;
An abutting member that abuts both the surface of the image carrier and the exposure apparatus, and adjusts a distance between the surface of the image carrier and the exposure apparatus;
Controlling the rotation operation of the image carrier, and at least one of the image carrier, the exposure device, and the contact member according to at least one of the number of start and stop times of the rotation of the image carrier An image forming apparatus comprising: a control unit that obtains a physical quantity related to one. Starting and stopping the rotation operation of the image carrier including the surface carrying the image, and exposing the surface by an exposure device to form an image; and
The surface of the image carrier and the exposure device are in contact with both the surface of the image carrier and the exposure device according to at least one of the number of start and stop times of the rotation operation of the image carrier. An amount of wear of at least one of the abutting member for adjusting the distance to the image bearing member and the image carrier. Starting and stopping the rotation operation of the image carrier including the surface carrying the image, and exposing the surface by an exposure device to form an image; and
An image forming method comprising: controlling at least one of an exposure light amount and an exposure time with respect to the surface by the exposure device in accordance with at least one of a start count and a stop count of the rotation operation of the image carrier. Starting and stopping the rotation operation of the image carrier including the surface carrying the image, and exposing the surface by an exposure device to form an image; and
The surface of the image carrier and the exposure device are in contact with both the surface of the image carrier and the exposure device according to at least one of the number of start and stop times of the rotation operation of the image carrier. An image forming method comprising: obtaining a replacement time of at least one of the contact member for adjusting the distance between the contact member and the image carrier.

Images