JP2021135413A - Image forming apparatus and method for controlling the same - Google Patents

Abstract

To provide an image forming apparatus that can perform control for stopping a separation member without increasing the number of components.SOLUTION: In separation control of rotating a brushless DC motor in a direction opposite to a rotation direction to drive a photoconductor drum to form an image to thereby separate the photoconductor drum from an electrifying roller, a pulse width counting unit of a motor driving device measures a PWM duty during the reverse rotation, and in accordance with the fact that the measured PWM duty during the reverse rotation exceeds a predetermined separation operation starting duty threshold A'', an FG counting unit starts counting FG pulse signals. The motor driving device stops the brushless DC motor in accordance with the fact that the counted number of FG pulse signals reaches a preset counting threshold S.SELECTED DRAWING: Figure 12

Description

The present invention relates to an image forming apparatus and a control method thereof.

An electrophotographic image forming apparatus including a photoconductor unit including a photoconductor and a charging roller is known. In the image forming apparatus, as a charging method for the photoconductor, for example, a contact charging method in which a charging roller is brought into contact with the photoconductor to charge the photoconductor is used. In an image forming apparatus using such a contact charging method, if the charging roller is in contact with the photoconductor for a long period of time without performing the image forming operation, the portion of the charging roller that is in contact with the photoconductor is deformed. Etc. occur. As a result, when image formation is performed, image defects occur.

In order to suppress the occurrence of such image defects, for example, the charging roller is separated from the photoconductor at the time of shipment of the image forming apparatus, and the separated charging roller comes into contact with the photoconductor by rotating the photoconductor. Is known (see, for example, Patent Document 1).

Further, the distance between the photoconductor and the charging roller is maintained by engaging the engaging portion that receives the driving force by engaging with the gear that rotates with the rotation of the photoconductor. An image forming apparatus is known that includes a separating member that can rotate between a release position that releases the state and allows the photoconductor and the charging roller to come into contact with each other (see, for example, Patent Document 2).

However, in the above-mentioned techniques of Patent Documents 1 and 2, if the image forming apparatus is not used for a long period of time due to a long vacation or the like after the photoconductor comes into contact with the charging roller, the above-mentioned problem occurs. On the other hand, by rotating the photoconductor in the direction opposite to the rotation direction in which the separation member is rotated from the separation position to the release position, the separation member is rotated from the release position to the separation position, and the photoconductor and the charging roller It is being studied to perform separation control to separate the two.

Japanese Unexamined Patent Publication No. 11-9532 Japanese Unexamined Patent Publication No. 2016-133776

However, in the above-mentioned separation control, in order to perform control for rotating the separation member from the release position and stopping it at the separation position with high accuracy, it is necessary to provide a sensor or the like for detecting the position of the separation member in the image forming apparatus. Yes, the number of parts will increase.

An object of the present invention is to provide an image forming apparatus capable of performing stop control of a separating member without increasing the number of parts.

In order to achieve the above object, the image forming apparatus of the present invention includes a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor. The apparatus includes a motor control means for rotating the motor in a direction opposite to the rotation direction for driving the image of the photoconductor to separate the photoconductor from the charging means, and the motor control means is provided. In the separation control, the duty of the PWM signal that determines the voltage applied to the motor is measured, and the rotation amount of the motor is measured according to the fact that the duty of the measured PWM signal exceeds the predetermined duty threshold. It is characterized in that the motor is started and stopped when the rotation amount of the motor reaches a preset predetermined amount.

According to the present invention, it is possible to control the stop of the separating member without increasing the number of parts.

It is a side view which shows roughly the structure of the image forming apparatus which concerns on embodiment of this invention. FIG. 5 is a block diagram schematically showing a configuration of a motor driving device for rotationally driving the photosensitive drum of FIG. 1. It is a side view of the drum cartridge in this embodiment. It is a perspective view which shows the structure around the drum cartridge of FIG. It is a figure for demonstrating the coupling of the photosensitive drum of FIG. It is a perspective view which shows the structure of the drum cartridge in a separated state. It is a figure for demonstrating the release operation of the separated state of the drum cartridge of FIG. It is a figure which shows the torque of the drive shaft of the photosensitive drum when the brushless DC motor of FIG. 2 is rotated forward. It is a figure which shows the torque of the drive shaft of the photosensitive drum when the brushless DC motor of FIG. 2 is rotated in the reverse direction. It is a figure which shows the result of having measured each operation state of the forward rotation and the reverse rotation of the photosensitive drum of FIG. It is a figure which shows the duty instruction amount which added the relative torque difference B. It is a figure for demonstrating the stop control of the separation holding member 200 in this embodiment. It is a block diagram which shows schematic structure of the pulse width count part and FG count part in 1st Embodiment. It is a flowchart which shows the procedure of the control processing executed by the motor drive device of FIG. It is a flowchart which shows the procedure of the PWM duty calculation process of step S105 of FIG. 14, and the separation control process of step S107. It is a block diagram which shows schematic the structure of the motor drive device included in the image forming apparatus in 2nd Embodiment. It is a flowchart which shows the procedure of the control processing executed by the motor drive device in 2nd Embodiment. It is a flowchart which shows the procedure of the separation control processing of step S302 of FIG. It is a block diagram which shows schematic structure of the motor drive device provided in the image forming apparatus in 3rd Embodiment. It is a flowchart which shows the procedure of the separation control processing executed by the motor drive device in 3rd Embodiment.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. First, the image forming apparatus according to the first embodiment of the present invention will be described.

FIG. 1 is a side view schematically showing a configuration of an image forming apparatus 1 according to an embodiment of the present invention. In FIG. 1, the internal configuration is transparently shown for ease of understanding.

The image forming apparatus 1 is a tandem type image forming apparatus adopting an intermediate transfer method. The image forming apparatus 1 forms a full-color image by using an electrophotographic method. The image forming apparatus 1 includes image forming units 100Y, 100M, 100C, and 100K that form toner images of each color of Y (yellow), M (magenta), C (cyan), and K (black), respectively. The configurations and operations of the image forming units 100Y, 100M, 100C, and 100K are substantially the same except that the colors of the toners used are different. Therefore, in the following, unless otherwise specified, the configuration will be described by omitting the trailing Y, M, C, and K indicating the corresponding colors in the image forming unit.

The image forming unit 100 includes a cylindrical photosensitive drum 11 as an image carrier. The drive of the photosensitive drum 11 is controlled by the motor drive device 160 of FIG. 2 provided in the image forming device 1, and the photosensitive drum 11 is rotationally driven at a predetermined process speed.

FIG. 2 is a block diagram schematically showing a configuration of a motor driving device 160 that rotationally drives the photosensitive drum 11 of FIG. 1. In FIG. 2, the motor drive device 160 includes a controller 151. The controller 151 includes a PID calculator 152, a PWM controller 153, and a cycle comparator 154. The controller 151 controls the speed so that the rotation speed of the photosensitive drum 11 becomes a predetermined process speed. For example, when the controller 151 receives an FG pulse signal having a period corresponding to the rotation speed from the brushless DC motor 150 driven by the photosensitive drum 11, the period of the FG pulse signal and the period corresponding to the target rotation speed are set to the period comparer 154. Compare by. The controller 151 inputs the comparison result to the PID calculator 152. Further, the controller 151 uses the PWM controller 153 to change the amount of voltage applied to the winding of the brushless DC motor 150 so that the rotation speed of the photosensitive drum 11 becomes constant. The PWM controller 153 generates a pulse voltage from the power supply voltage Vm based on the signal received from the PID calculator 152, and adjusts the on period (hereinafter, referred to as “duty”) of the pulse voltage to make a brushless DC. Adjust the average voltage applied to the windings of the motor 150.

Returning to FIG. 1, in the image forming unit 100, the charging roller 12, the exposure device 16, the developing device 14, the primary transfer roller 17, and the cleaning blade 15 are arranged in this order around the photosensitive drum 11 along the rotation direction thereof. Has been done.

The charging roller 12 is a rotatable roller-shaped charging member that charges the photosensitive drum 11. The exposure apparatus 16 is an exposure means such as a laser scanner apparatus. In the present embodiment, the surface of the photosensitive drum 11 is arranged so as to be exposed by the exposure apparatus 16. The developing device 14 is a developing means. Toner is supplied to the developing device 14 from a toner bottle 19 as a toner container via a toner transport path (not shown). The primary transfer roller 17 is a roller-shaped primary transfer member as a primary transfer means. The cleaning blade 15 is a cleaning means for cleaning the photosensitive drum 11. Further, in the image forming unit 100, a cleaning roller 13, which is a roller-shaped charging cleaning member for cleaning the charging roller 12, is arranged in contact with the charging roller 12. In the present embodiment, the charging roller 12 is in contact with the surface of the photosensitive drum 11 with a predetermined pressing force by an urging means such as a spring, and is driven to rotate as the photosensitive drum 11 rotates.

Further, the image forming apparatus 1 includes an intermediate transfer belt 61 as an intermediate transfer body. The intermediate transfer belt 61 is formed of an endless belt body, and is arranged so as to come into contact with the photosensitive drums 11 of the image forming portions 100Y, 100M, 100C, and 100K. The intermediate transfer belt 61 is hung around a plurality of support rollers (tension rollers) (not shown) with a predetermined tension. The above-mentioned primary transfer roller 17 is arranged at a position facing the photosensitive drum 11 on the inner peripheral surface side (back surface side) of the intermediate transfer belt 61. The primary transfer roller 17 is pressed against the photosensitive drum 11 via the intermediate transfer belt 61, and forms a primary transfer portion (primary transfer nip portion) N1 in which the intermediate transfer belt 61 and the photosensitive drum 11 come into contact with each other. The primary transfer roller 17 is driven to rotate as the intermediate transfer belt 61 rotates. On the outer peripheral surface side (surface side) of the intermediate transfer belt 61, the secondary transfer roller 35 as the secondary transfer means is arranged at a position facing the secondary transfer opposed roller 62. The secondary transfer roller 35 is a roller-shaped secondary transfer member. The secondary transfer roller 35 is pressed against the secondary transfer opposed roller 62 via the intermediate transfer belt 61, and the secondary transfer portion (secondary transfer nip portion) in which the intermediate transfer belt 61 and the secondary transfer roller 35 come into contact with each other. ) Forming N2. Further, a cleaning unit 70 as an intermediate transfer body cleaning means is arranged at a position facing the tension roller 64 on the outer peripheral surface side of the intermediate transfer belt 61. The intermediate transfer belt 61 is formed endlessly with a dielectric resin such as polyimide.

Further, the image forming apparatus 1 includes a resist roller pair 23, a fixing device 40, and the like. The resist roller pair 23 conveys a recording material P such as recording paper. The fixing device 40 fixes the toner image on the recording material P.

At the time of image formation, the surface of the photosensitive drum 11 that is driven to rotate is uniformly charged to a predetermined potential by the charging roller 12. In the present embodiment, a predetermined DC voltage is applied to the charging roller 12 from a high-voltage power supply (not shown) to generate an electric discharge on the surface of the photosensitive drum 11, so that the surface of the photosensitive drum 11 has a negative potential. Is charged.

After the surface of the photosensitive drum 11 is uniformly charged, the exposure apparatus 16 scans and exposes the surface of the photosensitive drum 11 based on the signal of the image information to form an electrostatic latent image on the photosensitive drum 11. The electrostatic latent image formed on the photosensitive drum 11 is developed as a toner image by the developing apparatus 14 using toner as a developing agent. In this embodiment, the normal charging polarity of the toner is negative. The developing apparatus 14 includes a developing sleeve (not shown) as a developing agent carrier that carries toner and conveys it to a portion facing the photosensitive drum 11. The developing sleeve is rotationally driven. At the time of development, a predetermined development voltage (development bias) is applied to the development sleeve from a high-voltage power source (not shown) as a development power source. In the present embodiment, as the development voltage, a vibration voltage in which a DC voltage (DC component) and an AC voltage (AC component) are superimposed is used.

The toner image formed on the photosensitive drum 11 is transferred (primary transfer) to the surface of the intermediate transfer belt 61 by the action of the primary transfer roller 17 in the primary transfer unit N1. At this time, the primary transfer roller 17 receives a primary transfer voltage (primary transfer) from the primary transfer power supply (not shown), which is a DC voltage having a polarity (positive electrode) opposite to the charging polarity (negative electrode) of the toner during development. Bias) is applied. When forming a full-color image, the above-mentioned operations are performed in each of the image forming units 100Y, 100M, 100C, and 100K. The yellow, magenta, cyan, and black toner images formed on each photosensitive drum 11 are sequentially superimposed and transferred onto the intermediate transfer belt 61. After the transfer, a small amount of transfer residual toner remaining on the photosensitive drum 11 is removed by the cleaning blade 15 as a cleaning member and collected by a collection unit (not shown).

On the other hand, the recording materials P are fed one by one from the paper feed cassette 20 and conveyed to the resist roller pair 23. After that, the resist roller pair 23 transfers the recording material P between the intermediate transfer belt 61 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 61. The color toner image on the intermediate transfer belt 61 is transferred (secondary transfer) to the surface of the recording material P by the action of the secondary transfer roller 35 in the secondary transfer unit N2. When the recording material P passes through the secondary transfer unit N2, the secondary transfer roller 35 receives a DC voltage from the secondary transfer power supply (not shown) having a polarity opposite to the charging polarity of the toner during development. A secondary transfer voltage (secondary transfer bias) is applied. After the transfer, a small amount of residual toner remaining on the intermediate transfer belt 61 is removed and recovered by the cleaning unit 70. The toner image transferred onto the recording material P is fixed by heating and pressurizing by the fixing device 40, and is discharged onto the paper ejection tray 50 by the paper ejecting roller pair 41.

FIG. 3 is a side view of the drum cartridge 101 according to the present embodiment. FIG. 4 is a perspective view showing the configuration around the drum cartridge 101 of FIG. In FIG. 3, the internal configuration is transparently shown for ease of understanding. In the present embodiment, the image forming units 100Y, 100M, 100C, and 100K each include a drum cartridge 101.

In FIGS. 3 and 4, the drum cartridge 101 has a configuration in which the photosensitive drum 11, the charging roller 12, the cleaning roller 13, and the cleaning blade 15 are integrally held by the drum container 30 as a frame body. The drum cartridge 101 is removable from the image forming apparatus 1 and is replaced by maintenance or the like.

In the drum container 30, the photosensitive drum 11 is rotatably held around a rotation axis via a bearing (not shown). The photosensitive drum 11 is provided with the coupling 39 of FIG. 5 for receiving a driving force from the motor driving device 160 and rotating the photosensitive drum 11 while being mounted on the image forming device 1.

Further, a cleaning blade 15 for cleaning the surface of the photosensitive drum 11 is fixed to the drum container 30 so as to come into contact with the surface of the photosensitive drum 11. A recovery unit (not shown) and a toner transfer screw 38 are provided in the vicinity of the cleaning blade 15. The recovery unit collects the transfer residual toner removed from the surface of the photosensitive drum 11 by the cleaning blade 15. The toner transport screw 38 is a transport section for transporting the recovered toner to the recovery section and transporting the toner to the outside of the drum cartridge 101. The toner conveyed to the outside of the drum cartridge 101 by the toner transfer screw 38 is collected in a waste toner container (not shown) provided in the image forming apparatus 1.

As shown in FIG. 4, a gear 36 as a rotating member fixed so as to rotate integrally with the photosensitive drum 11 about the rotation axis of the photosensitive drum 11 is provided at an end portion of the photosensitive drum 11 in the longitudinal direction. There is. The rotational force of the gear 36, which rotates integrally when the photosensitive drum 11 rotates, is transmitted to the toner transfer screw 38, so that the toner transfer screw 38 rotates, and the transfer residual toner collected in the collection unit is transferred to the outside of the drum cartridge 101. Will be done.

As shown in FIG. 5, the charging roller 12 is a roller including a rotating shaft 12a which is a conductive support (core metal, core material) and one or more elastic layers 12b formed around the rotating shaft 12a. It is a shaped member. The outer peripheral surface of the charging roller 12 is configured to come into contact with the photosensitive drum 11. The rotating shaft 12a is held by the charging roller bearing 31 of FIG. 4 as a holding portion of the charging roller 12, so that the charging roller 12 is rotatably supported. Further, the charging roller bearing 31 is slidably supported with respect to the drum container 30. Specifically, the charging roller bearing 31 is configured to be slidable in the direction toward the rotation axis of the photosensitive drum 11. As a result, the supported charging roller 12 can move along the direction toward the rotation axis of the photosensitive drum 11 on the plane perpendicular to the rotation axis of the photosensitive drum 11. Further, a charging roller pressure spring 32 of FIG. 5 as a first urging means is provided between the drum container 30 and the charging roller bearing 31. Since the charging roller pressurizing spring 32 urges the charging roller 12 in the direction (biasing direction) toward the rotation axis of the photosensitive drum 11 on the plane perpendicular to the rotation axis of the photosensitive drum 11, the charging roller 12 has a charging roller 12. The photosensitive drum 11 is pressurized and is in contact with the photosensitive drum 11.

As shown in FIG. 5, the cleaning roller 13 includes a rotating shaft 13a which is a rod-shaped support portion (core metal, core material), and an elastic layer 13b formed around the rotating shaft 13a. The outer peripheral surface of the cleaning roller 13 comes into contact with the charging roller 12. The elastic layer 13b includes a foamed elastic layer as an outermost layer (contact portion) that contacts the surface (outer peripheral surface) of the charging roller 12. The cleaning roller 13 is rotatably supported by the rotating shaft 13a being supported by the cleaning roller bearing 33 of FIG. The cleaning roller bearing 33 is slidably supported with respect to the charging roller bearing 31. Specifically, the cleaning roller 13 is configured so that the cleaning roller bearing 33 can slide in the direction toward the rotation axis of the separation holding member 200 (the direction toward the rotation axis of the charging roller 12). As a result, the cleaning roller 13 can move along the direction toward the rotation axis of the separation holding member 200 (the direction toward the rotation axis of the charging roller 12) on the plane perpendicular to the rotation axis of the separation holding member 200. ..

Further, a cleaning roller pressure spring 34 as a second urging means is provided between the charging roller bearing 31 and the cleaning roller bearing 33. The direction in which the cleaning roller pressure spring 34 separates the cleaning roller 13 toward the rotation axis of the separation holding member 200 on the plane perpendicular to the rotation axis of the separation holding member 200 (direction toward the rotation axis of the charging roller 12) (biasing). Direction). Therefore, the cleaning roller 13 is pressed against the charging roller 12 and is in contact with the charging roller 12. That is, the cleaning roller 13 is configured to be movable along the urging direction of the cleaning roller pressure spring 34. In the present embodiment, the urging direction by the first urging means and the urging direction by the second urging means are the same direction.

With the above configuration, when the photosensitive drum 11 receives a driving force from a driving source provided in the image forming apparatus 1 and rotates, the charging roller 12 is driven to rotate due to the frictional force with the photosensitive drum 11. When the charging roller 12 rotates, the cleaning roller 13 is driven to rotate due to the frictional force with the charging roller 12. Further, the toner transport screw 38 rotates by receiving a driving force by the gear 36.

Further, with the above configuration, the cleaning roller 13 moves in the moving direction of the charging roller 12 in conjunction with the movement of the charging roller 12 in the direction away from the photosensitive drum 11.

Next, a separation holding mechanism for holding the photosensitive drum 11 and the charging roller 12 in a separated state will be described. Since the configurations of both ends of the charging roller 12 are the same, in the present embodiment, as an example, a diagram showing only one side will be described.

As shown in FIGS. 5 and 6, the drum cartridge 101 is used to secure clearance between the charging roller 12 and the photosensitive drum 11 and between the charging roller 12 and the cleaning roller 13 during transportation for distribution. A separation holding member 200 is provided.

The separation holding member 200 is rotatably provided at both ends of the rotating shaft 12a of the charging roller 12 with the rotating shaft 12a of the charging roller 12 as a rotating shaft. That is, the separation holding member 200 is rotatably supported by the charging roller 12 about the rotation axis of the charging roller 12. Therefore, the separation holding member 200 can move in conjunction with the rotation of the charging roller 12.

The separation holding member 200 includes a separation holding portion 210 for separating the photosensitive drum 11 and the charging roller 12, and a separation holding portion 220 for separating the charging roller 12 and the cleaning roller 13. In a state where the photosensitive drum 11, the charging roller 12, the charging roller 12 and the cleaning roller 13 are separated from each other (hereinafter, referred to as “separation state”), the separation holding portion 210 presses the charging roller pressure spring 32 (attached). It is sandwiched between the rotating shaft 12a of the charging roller 12 (the rotating shaft of the separation holding member 200) and the gear 36 by the force). Further, in the separated state, the separated holding portion 220 is pressed by the cleaning roller 13 by the pressing force (urging force) of the cleaning roller pressure spring 34, and is between the rotating shaft 12a of the charging roller 12 and the rotating shaft 13a of the cleaning roller 13. It is sandwiched between. As a result, the elastic layer 12b of the charging roller 12 is separated from the photosensitive drum 11, and the charging roller 12 is separated from the cleaning roller 13 to ensure mutual clearance. In the present embodiment, the above-mentioned separated state is maintained from the time when the drum cartridge 101 is shipped until the drum cartridge 101 is attached to the image forming apparatus 1 and the release operation described later is performed.

FIG. 7 is a diagram for explaining the operation of releasing the separated state of the drum cartridge 101 of FIG.

When the user attaches the drum cartridge 101 to the image forming apparatus 1 and activates the image forming apparatus 1, the driving force (rotational force) from the brushless DC motor 150 that has rotated forward to the photosensitive drum 11 due to the initial operation of the image forming apparatus 1. ) Is transmitted, and the photosensitive drum 11 starts to rotate. For example, when the photosensitive drum 11 starts to rotate from the separated state of the drum cartridge 101 shown in FIG. 7A, the gear 36 starts to rotate in accordance with the photosensitive drum 11. When the gear 36 rotates, the engaging portion 211 of the separation holding member 200 engaged with the gear 36 rotates by receiving the rotational force of the gear 36. As the separation holding member 200 rotates, the rotation shaft 13a of the cleaning roller 13 gets over the end on the upstream side of the receiving surface 221 in the rotation direction of the separation holding member 200 (see, for example, FIG. 7B). ). After that, when the separation holding member 200 is further rotated by the rotation of the gear 36, the gear 36 and the engaging portion 211 do not mesh with each other as shown in FIG. 7C. At this time, an urging force acts on the cleaning roller 13 in the A direction by the cleaning roller pressure spring 34. The force in the A direction is converted into a force in which the separation holding member 200 rotates in the B direction by the separation auxiliary surface 222 (contact portion) provided on the separation holding member 200. The B direction is the same direction as the direction in which the separation holding member 200 rotates when the separation state is released. The separation auxiliary surface 222 is located further upstream than the upstream end of the receiving surface 221 in the rotation direction when the driving force is received from the gear 36, and becomes shorter as it becomes downstream in the rotation direction. .. By forming the contact portion in this way, the force in the A direction is converted into a force that rotates in the B direction. In other words, when the engaging portion 211 is disengaged from the gear 36, the rotation shaft 13a of the cleaning roller 13 comes into contact with the separation auxiliary surface 222, and the separation auxiliary surface 222 is applied to the cleaning roller from the rotation shaft 13a of the cleaning roller 13. By receiving the urging force by the pressure spring 34, the separation holding member 200 rotates in the direction in which the engaging portion 211 is separated from the gear 36.

After that, as shown in FIG. 7D, the engaging portion 211 of the separation holding member 200 is separated from the gear 36, the charging roller 12 comes into contact with the surface of the photosensitive drum 11, and the cleaning roller 13 comes into contact with the charging roller 12. Then, the separated state is released. As described above, when the brushless DC motor 150 rotates in the forward direction, the separation holding member 200 is released from the position where the separation state is held (hereinafter, referred to as “separation holding position”) (hereinafter, “release”). It is a configuration that can be rotated to "position"). When the separated state is released, the charging roller 12 comes into contact with the photosensitive drum 11 and charges the surface of the photosensitive drum 11 to a predetermined voltage level as described above.

Further, in the present embodiment, the separation holding member 200 is configured to be rotatable from the release position to the separation holding position by rotating the brushless DC motor 150 in the reverse direction in the state where the separation state is released.

In the state where the separated state is released, the driving force is transmitted from the brushless DC motor 150 that has rotated in the reverse direction to the photosensitive drum 11, the photosensitive drum 11 starts to rotate, and the charging roller 12 that is in contact with the photosensitive drum 11 is driven to drive the above. It starts to rotate in the direction opposite to the direction of rotation in the movement. When the charging roller 12 rotates to a certain rotation angle, the separation gear of the separation holding portion 210 starts meshing with the gear 36. When further rotated, the separation holding member 200 rotates to the separation holding position. In the present embodiment, the abutting mechanism 230 (movement limiting means) of FIG. 7A is provided to limit the rotation of the gear 36. This makes it possible to prevent the separation holding member 200 from unnecessarily rotating beyond the release position. The torque required for the above-mentioned operation will be described with reference to FIGS. 8 and 9.

FIG. 8 is a diagram showing the torque of the drive shaft of the photosensitive drum 11 when the brushless DC motor 150 of FIG. 2 is rotated in the forward direction. In FIG. 8, the torque (“A” in FIG. 8) generated by the contact of the photosensitive drum 11 with the cleaning blade 15 is shown.

FIG. 9 is a diagram showing the torque of the drive shaft of the photosensitive drum 11 when the brushless DC motor 150 of FIG. 2 is rotated in the reverse direction. In FIG. 9, the torque (“A ′” in FIG. 9) generated by the contact of the photosensitive drum 11 with the cleaning blade 15 is shown. The torque A'does not include the torque generated by the separation operation in which the separation holding member 200 rotates from the release position to the separation holding position. Further, in FIG. 9, the amount of change in torque due to the separation operation (“Δtrq” in FIG. 9) is shown.

The forward rotation torque A and the reverse rotation torque A'are generated when the photosensitive drum 11 comes into contact with the cleaning blade 15, and change depending on the state of adhesion of toner on the surface of the photosensitive drum 11. The relationship between these torques is that torque A during forward rotation> torque A ′ during reverse rotation. Further, since these torques are generated when the photosensitive drum 11 comes into contact with the cleaning blade 15 as described above, the relative difference (hereinafter, referred to as “relative torque difference”) B is a substantially constant amount (≈ forward rotation). Hour torque A-Reverse rotation torque A'). Therefore, if the forward rotation torque A can be detected, the reverse rotation torque A'(= normal rotation torque A-relative torque difference B) is based on the detected forward rotation torque A and the relative torque difference B. ) Can be calculated. Further, it is also possible to add the torque change amount Δtrq due to the separation operation to the calculated reverse rotation torque A'to calculate the torque in consideration of the separation operation. When a torque that takes into account the separation operation is obtained, for example, the separation start position X in FIG. 9 at which the separation gear of the separation holding portion 210 starts meshing with the gear 36 can be detected based on the change in the torque. .. From FIG. 9, it can be read that the torque sharply increases from the position where the separation holding portion 210 abuts the abutting mechanism 230 (hereinafter, referred to as the "butting position" and is indicated by Y in FIG. 9).

FIG. 10 is a diagram showing the results of measuring the forward rotation and reverse rotation operation states of the photosensitive drum 11 of FIG. In FIG. 10, the period R indicates a duty instruction amount that is a speed control amount of the brushless DC motor 150 with respect to the torque at the time of forward rotation of the brushless DC motor 150. The period R'indicates the duty instruction amount of the brushless DC motor 150 with respect to the torque at the time of reverse rotation of the brushless DC motor 150. In FIG. 10, the duty indicated amount (period R) during forward rotation is shown at the same level as the duty indicated amount (period R') during reverse rotation. This is because the measurement results for a predetermined time after the brushless DC motor 150 starts driving are masked, and the torque due to the separation operation is added to the period R'. The duty indicated amount after subtracting the relative torque difference B described above is shown by the alternate long and short dash line in FIG.

Here, as described above, the photosensitive drum 11 is driven by the controller 151 controlling the rotation speed of the brushless DC motor 150. The voltage applied to the brushless DC motor 150 at this time is determined by the duty of the PWM signal output from the PWM controller 153 constituting the controller 151, and this duty is controlled according to the change in the torque. That is, the above-mentioned change in torque can be detected from the duty of the PWM signal output from the PWM controller 153.

In the present embodiment, the separation start position X required for the stop control of the separation holding member 200 is detected based on the duty of the PWM signal output from the PWM controller 153. Here, the brushless DC motor 150 detects the magnetic pole position using a Hall element, and can obtain only a resolution of an electric angle of 60 degrees. When the brushless DC motor 150 is used, it is necessary to use a rotation position detecting means such as an encoder in order to acquire the position information of the separation holding member 200 required for the stop control of the separation holding member 200. On the other hand, in the present embodiment, the separation start position X is detected based on the duty of the PWM signal output from the PWM controller 153. Thereby, the information necessary for the stop control of the separation holding member 200 can be acquired without providing the rotation position detecting means.

Further, in the present embodiment, according to the detection of the separation start position X, the stop control of the separation holding member 200 is performed based on the rotation amount of the brushless DC motor 150 for which the measurement is started. Specifically, counting of the FG pulse signal output from the brushless DC motor 150 is started, and stop control of the separation holding member 200 is performed based on the count number of the FG pulse signal.

Here, since the FG pulse signal is generated as an induced voltage based on the change in magnetic flux due to the rotation of the rotor, the rotation speed is slower than the output speed FG_lim of the FG pulse signal (shown in FIG. 12A). ) Cannot be used. Further, the stop position cannot be controlled during the deceleration period (indicated by (b) in FIG. 12) by the brushless DC motor 150 and the brake.

On the other hand, in the present embodiment, the separation start position X is detected in the period excluding the period (a) and the period (b) of FIG. 12, and the counting of the FG pulse signal is started according to the detection of the separation start position X. .. When the count number of the FG pulse signal reaches the count threshold value S in FIG. 12, the stop control of the separation holding member 200 is performed. As a result, in the motor control system having the above-mentioned restrictions, the stop control of the separation holding member 200 can be performed with high accuracy. By performing the above-mentioned control, the accuracy of the stop control is determined as follows.

As the equation of motion when the motor is stopped, if the motor speed immediately before deceleration is ωm and the time until the stop (ωm → 0) is t_stop, the following equation (1) can be obtained from the relational expression between torque and acceleration.

Trq_stop = J × dω / dt = J × (ωm-0) / t_stop… (1)
Assuming that the brake is used in the formula (1), the stop time t_brk in the period (b) is calculated by the following formula (2).

t_brk = J × ωm / Trq_stop… (2)
here,
J [kg ・ m ² ] = Jm + Jl (Jm: rotor moment of inertia, Jl: load moment of inertia)
ωm [rad / s]: Motor angular velocity Trq_stop = Tbrk + Tl [Nm] (Tbrk: braking torque by brake, Tl: load torque).

The rotation angle θstop when stopped by this brake is given by the following equation (3).

θstop [rad] = 1/2 x ωm x t_brk ... (3)
In such a stop by the brake, even if the torque changes like (0 to 100 mNm), there is a braking torque (about 40 mNm at 500 rpm). Therefore, the fluctuation range of the rotation distance until the stop can be suppressed to about 1/9, and the stop control can be performed with an accuracy of about 5 deg or less. This means that the vehicle can be stopped with a margin of about 8 times the mechanical stop position range of about 40 deg, and the stop control accuracy is sufficient.

Next, the details of the detection of the separation start position X and the stop control by the FG pulse signal will be described.

In the present embodiment, the pulse width counting unit 155 of FIG. 13A of the motor driving device 160 measures the duty of the PWM signal output from the PWM controller 153 (hereinafter, referred to as “PWM duty”). The separation start position X is detected based on the measurement result. As shown in FIG. 13B, the pulse width counting unit 155 counts the reference clock from the rising edge of the PWM signal to the falling edge of the PWM signal, and the PWM duty, that is, the width of the ON pulse of the PWM signal. To measure. When the number of counts of the reference clock reaches a predetermined number (the width of the ON pulse of the PWM signal is a predetermined width), the pulse width counting unit 155 notifies the controller 151 to that effect. Upon receiving this notification, the controller 151 instructs the FG counting unit 156 of FIG. 13A of the motor driving device 160 to start counting the FG pulse signal.

Upon receiving the instruction, the FG counting unit 156 counts the falling edge (or rising edge) of the FG pulse signal output by the brushless DC motor 150. When the count number reaches the count threshold value S in FIG. 12, the FG count unit 156 notifies the controller 151 to that effect. Upon receiving this notification, the controller 151 controls to stop the brushless DC motor 150.

FIG. 14 is a flowchart showing a procedure of control processing executed by the motor drive device 160 of FIG. The process of FIG. 14 is executed, for example, when the image forming apparatus 1 is activated. In the process of FIG. 14, it is assumed that either the image forming mode or the separation mode is preset in the image forming apparatus 1. When the image drawing mode is set, the motor drive device 160 rotates the brushless DC motor 150 in the forward direction to drive the photosensitive drum 11 in image formation. When the separation mode is set, the motor drive device 160 reversely rotates the brushless DC motor 150 to rotate the separation holding member 200 from the release position to the separation holding position.

In FIG. 14, the motor drive device 160 determines which of the image drawing mode and the separation mode is set (step S101).

As a result of the determination in step S101, when the image drawing mode is set, the motor drive device 160 performs the initial setting (step S102). For example, in step S102, the rotation direction of the brushless DC motor 150 is set to forward rotation. Further, in step S102, the rotation speed of the brushless DC motor 150, various control parameters required for image drawing drive, and the like are set. Next, the motor driving device 160 starts driving the brushless DC motor 150 according to the latent image forming sequence (step S103), and ends this process.

As a result of the determination in step S101, when the separation mode is set, the motor drive device 160 performs the initial setting (step S104). In step S104, various settings used in the processes of steps S105 and S107 described later, for example, the relative torque difference B, the torque change amount ΔTrq, and the count threshold value S are set.

Next, the motor drive device 160 executes the PWM duty calculation process of FIG. 15 (a) described later (step S105), and the duty of the PWM signal corresponding to the torque A'during reverse rotation (hereinafter, "PWM duty A'"). ”) Is calculated. Next, the motor drive device 160 waits until the vibration of the brushless DC motor 150, which has stopped rotating in step S105, subsides. Specifically, the motor drive device 160 waits until a preset predetermined time, for example, 100 ms has elapsed (step S106). Next, the motor drive device 160 executes the separation control process of FIG. 15B described later (step S107), rotates the brushless DC motor 150 in the reverse direction, and stops the separation holding member 200 at the separation holding position. Next, the motor drive device 160 stops the counting operation by the pulse width counting unit 155 and the FG counting unit 156 performed in step S107 (step S108), prepares to shift to the image drawing mode, and performs this processing. finish.

FIG. 15A is a flowchart showing the procedure of the PWM duty calculation process in step S105 of FIG. In the PWM duty calculation process, the PWM duty A corresponding to the torque A at the time of forward rotation is measured, and the torque A'at the time of reverse rotation is based on the PWM duty A and the relative torque difference B set in step S104. The PWM duty A'corresponding to is calculated.

In FIG. 15A, the motor drive device 160 sets the rotation direction of the brushless DC motor 150 to forward rotation (step S201), and causes the brushless DC motor 150 to rotate forward (step S202). The motor drive 160 then masks the start-up period. When the rotation speed of the brushless DC motor 150 stabilizes at a predetermined speed, the motor drive device 160 starts measuring the PWM duty during normal rotation (step S203). Specifically, the pulse width counting unit 155 of the motor drive device 160 counts the reference clock from the rising edge of the PWM signal to the falling edge of the PWM signal, and determines the width (PWM duty) of the ON pulse of each PWM signal. measure. The pulse width counting unit 155 continues to measure the width of the ON pulse of the PWM signal until the number of counts of the FG pulse signal by the FG counting unit 156 reaches a predetermined number. When the count number of the FG pulse signal reaches a predetermined number (YES in step S204), the motor drive device 160 averages the measured results to calculate the PWM duty A. Next, the motor drive device 160 calculates the PWM duty A'corresponding to the torque at the time of reverse rotation based on the calculated PWM duty A and the relative torque difference B set in step S104 (step S205). .. As described above, the PWM duty A'does not include the torque generated by the separation operation. Next, the motor drive device 160 adds the value corresponding to the torque change amount ΔTrq set in step S104 to the PWM duty A', and the separation operation start duty threshold value A for detecting the separation start position X. The motor driving device 160 stores the determined separation operation start duty threshold value A ”in the storage (not shown) of the image forming apparatus 1 and stops the rotation of the brushless DC motor 150 (step S206). This process ends.

FIG. 15B is a flowchart showing the procedure of the separation control process in step S107 of FIG. In the separation control process, counting of the FG pulse signal is started when the measured PWM duty at the time of reverse rotation exceeds the separation operation start duty threshold value A ”, and the count number of the FG pulse signal reaches the count threshold value S. , The separation holding member 200 is stopped.

In FIG. 15B, the motor drive device 160 sets the rotation direction of the brushless DC motor 150 to reverse rotation (step S207), and reversely rotates the brushless DC motor 150 (step S208). The motor drive 160 then masks the start-up period. When the rotation speed of the brushless DC motor 150 stabilizes at a predetermined speed, the motor drive device 160 starts measuring the PWM duty during reverse rotation (step S209). Specifically, the pulse width counting unit 155 counts the reference clock from the rising edge of the PWM signal to the falling edge of the PWM signal, and measures the width (PWM duty) of the ON pulse of each PWM signal. The pulse width counting unit 155 continues to measure the PWM duty during reverse rotation until the PWM duty exceeds the separation operation start duty threshold value A ”set in step S104. The measured PWM duty during reverse rotation is separated. When the operation start duty threshold value A ”is exceeded (YES in step S210), the motor drive device 160 causes the FG counting unit 156 to start counting the FG pulse signal. When the count number of the FG pulse signal reaches the count threshold value S set in step S104 (YES in step S211), the rotation of the brushless DC motor 150 is stopped (step S212). As a result, the drum cartridge 101 is separated. After that, the motor drive device 160 ends this process.

According to the above-described embodiment, in the separation control in which the brushless DC motor 150 is rotated in the direction opposite to the rotation direction for driving the image of the photosensitive drum 11 to separate the photosensitive drum 11 from the charging roller 12, the motor driving device 160 is used. , The pulse width counting unit 155 measures the PWM duty during reverse rotation. When the measured PWM duty at the time of reverse rotation exceeds the predetermined separation operation start duty threshold value A ”, the FG counting unit 156 of the motor driving device 160 starts counting the FG pulse signal. The motor driving device 160 starts counting the FG pulse signal. When the count number of the FG pulse signal reaches the preset count threshold value S, the brushless DC motor 150 is stopped. That is, the information required for the separation control is a sensor or the like that detects the position of the separation holding member 200. It is acquired by the pulse width counting unit 155 and the FG counting unit 156 of the motor driving device 160 without using it. Thereby, the stop control of the separation holding member 200 can be performed without increasing the number of parts.

Further, in the above-described embodiment, the separation operation start duty threshold value A ”is based on the PWM duty A during normal rotation, the preset relative torque difference B, and the torque change amount ΔTrq / 2 (set value) due to the separation operation. As a result, the separation operation start duty threshold value A "for detecting the separation start position X required for the stop control of the separation holding member 200 can be determined without increasing the number of parts.

In the above-described embodiment, the rotation speed of the brushless DC motor 150 is measured based on the count number of the FG pulse signals whose frequency changes according to the rotation speed of the brushless DC motor 150. As a result, the separation holding member 200 can be stopped at the separation holding position without increasing the number of parts.

Although the present invention has been described above with reference to the above-described embodiments, the present invention is not limited to the above-described embodiments. For example, the PWM duty A may be measured during the image drawing drive, and the PWM duty A'may be calculated based on the measured PWM duty A. As a result, in the separation mode, the processing of steps S105 and S106 can be omitted, and thus the time required for the separation operation can be shortened.

Next, the image forming apparatus according to the second embodiment of the present invention will be described. The configuration and operation of the present embodiment are basically the same as those of the first embodiment described above, and the first embodiment described above is started in that the count of the FG pulse signal is started after the abutting position is detected. It is different from the form of. Therefore, the description of the duplicated configuration and action will be omitted, and the different configurations and actions will be described below.

The engaging portion 211 of the gear 36 and the separation holding member 200 is designed to have durability that can withstand a torque several times or more the torque of normal operation. Therefore, the gear 36 and the engaging portion 211 of the separation holding member 200 do not cause tooth skipping or failure to the extent that the separation holding member 200 abuts against the abutting mechanism 230. In consideration of these durability performances, in the present embodiment, the FG pulse signal in which the separation holding member 200 detects the abutting position where the abutting mechanism 230 abuts, detects the abutting position, and then starts counting. When the count number reaches a predetermined number, the separation holding member 200 is stopped.

FIG. 16 is a configuration diagram schematically showing the configuration of the motor drive device 160'provided by the image forming apparatus 1'in the second embodiment. In FIG. 16, the motor drive device 160'includes a controller 151, an FG counting unit 157, and a pulse width counting unit 158. The FG count unit 157 starts counting the FG pulse signal at the same time as the start of driving the brushless DC motor 150. The pulse width counting unit 158 measures the PWM duty. The PWM duty measurement process by the pulse width counting unit 158 is executed in parallel with the FG pulse signal counting process by the FG counting unit 157.

FIG. 17 is a flowchart showing a procedure of control processing executed by the motor driving device 160'in the second embodiment. The process of FIG. 17 is executed, for example, when the image forming apparatus 1'is activated. In the process of FIG. 17, it is assumed that either the image forming mode or the separation mode is preset in the image forming apparatus 1'.

In FIG. 17, the motor drive device 160'performs the process of step S101. As a result of the determination in step S101, when the image drawing mode is set, the motor drive device 160'performs the processes after step S102.

As a result of the determination in step S101, when the separation mode is set, the motor drive device 160'makes an initial setting (step S301). In step S301, various settings used in the process of step S302 described later, for example, the abutting duty threshold C and the count threshold R'are set. The abutting duty threshold value C is a value at which the gear 36 and the gear of the separation holding member 200 do not fail when the separation holding member 200 abuts against the abutting mechanism 230. The count threshold value R'is the predicted count number of the FG pulse signal counted from the start of reverse rotation of the brushless DC motor 150 to the time when the separation holding member 200 abuts on the abutting mechanism 230 in the state where the separation state is released. be.

Next, the motor drive device 160'executes the separation control process of FIG. 18 described later (step S302), rotates the brushless DC motor 150 in the reverse direction, and stops the separation holding member 200 at the separation holding position. Next, the motor drive device 160'stops the counting operation by the pulse width counting unit 158 and the FG counting unit 157 performed in step S302 (step S303), prepares to shift to the image drawing mode, and performs this process. finish.

FIG. 18 is a flowchart showing the procedure of the separation control process in step S302 of FIG.

In FIG. 18, the motor drive device 160'sets the rotation direction of the brushless DC motor 150 to reverse rotation (step S401), and reversely rotates the brushless DC motor 150 (step S402). When the brushless DC motor 150 starts to rotate in the reverse direction, the motor drive device 160'executes the measurement of the PWM duty during the reverse rotation and the counting of the FG pulse signal in parallel (step S403). In step S403, the pulse width counting unit 158 counts the reference clock from the rising edge of the PWM signal to the falling edge of the PWM signal, and measures the width (PWM duty) of the ON pulse of each PWM signal. Further, in step S403, the FG counting unit 157 counts the rising edge (or falling edge) of the FG pulse signal.

When the measured PWM duty at the time of reversal exceeds the abutting duty threshold C or the count number of the FG pulse signal reaches the count threshold R'(YES in step S404), the motor drive device 160'is the brushless DC motor 150. The rotation is stopped (step S405). As a result, the drum cartridge 101 is separated. After that, the motor drive device 160'ends this process.

In the above-described embodiment, in the separation control, the FG counting unit 157 starts counting the FG pulse signal based on the start of rotation of the brushless DC motor 150, and the pulse width counting unit 158 starts the PWM duty when rotating in the reverse direction. To measure. When the count number of the FG pulse signal reaches the preset count threshold value R', or when the measured PWM duty during reverse rotation exceeds the abutting duty threshold value C, the motor drive device 160'is a brushless DC motor. Stop 150. Thereby, the stop control of the separating member can be performed without increasing the number of parts.

Further, in the above-described embodiment, the abutting duty threshold value C is a value at which the gear 36 and the gear of the separation holding member 200 do not fail when the separation holding member 200 abuts against the abutting mechanism 230. As a result, the separation holding member 200 can be stopped without breaking the gears of the gear 36 and the separation holding member 200.

Next, the image forming apparatus according to the third embodiment of the present invention will be described. The configuration and operation of the present embodiment are basically the same as those of the first embodiment and the second embodiment described above, and the separation control is performed without measuring the PWM duty. It is different from the first embodiment and the second embodiment. Therefore, the description of the duplicated configuration and action will be omitted, and the different configurations and actions will be described below.

FIG. 19 is a configuration diagram schematically showing the configuration of the motor drive device 160 "included in the image forming apparatus 1" according to the third embodiment. In FIG. 19, the motor drive device 160 ”includes a controller 151 and an FG count unit 157.

The motor drive device 160 "executes the control process of FIG. 14 when, for example, the image forming device 1" is activated. In the control process executed by the motor drive device 160 ”, the separation control process of FIG. 20 is performed in step S107.

FIG. 20 is a flowchart showing a procedure of the separation control process executed by the motor drive device 160 ”in the third embodiment. In FIG. 20, the abutting prediction time is set in step S104. The abutting predicted time is the predicted time required from the start of reverse rotation of the brushless DC motor 150 to the rotation of the separation holding member 200 to the abutting position.

In FIG. 20, the motor drive device 160 ”sets the rotation direction of the brushless DC motor 150 to reverse rotation (step S501) and reverse-rotates the brushless DC motor 150 (step S502). The brushless DC motor 150 rotates in the reverse direction. When started, the motor drive device 160 ”starts counting the FG pulse signal by the FG counting unit 157 and measuring the elapsed time by a timer (not shown) (step S503).

When the count number of the FG pulse signal reaches the count threshold value S or the measured elapsed time reaches the estimated time (YES in step S504), the motor drive device 160 ”stops the rotation of the brushless DC motor 150. (Step S505). As a result, the drum cartridge 101 is separated. After that, the motor drive device 160 "ends this process.

In the above-described embodiment, in the separation control, the motor drive device 160 "starts counting the FG pulse signal by the FG counting unit 157 based on the start of rotation of the brushless DC motor 150, and the brushless DC motor 150. The measurement of the elapsed time from the start of rotation is started. When the count number of the FG pulse signal reaches the preset count threshold S, or when the elapsed time reaches the estimated time, the motor drive device 160 ”stops the brushless DC motor 150. Thereby, the stop control of the separating member can be performed without increasing the number of parts.

Further, in the above-described embodiment, the brushless DC motor is executed in the process of step S104 before the process of step S107 is executed, that is, immediately before the separation control is performed, to drive the photosensitive drum 11 in image formation. Rotate 150. As a result, the brushless DC motor 150 is rotated in the reverse direction and the separation holding member 200 is pressed against the abutting mechanism 230 to damage the gear 36 and the engaging portion 211 of the separation holding member 200 even though the distance is in the separated state. Can be prevented.

1 Image forming device 11 Photosensitive drum 155,158 Pulse width counting unit 156,157 FG counting unit 160 Motor drive device 200 Separation holding member 230 Abutting mechanism A ”Distance operation start duty threshold value C Butting duty threshold value S, R Count threshold value

Claims (11)

An image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
A motor control means for controlling the distance of the photoconductor by rotating the motor in the direction opposite to the rotation direction for driving the image of the photoconductor to separate the photoconductor from the charging means is provided.
In the separation control, the motor control means
The duty of the PWM signal that determines the voltage applied to the motor is measured and
When the duty of the measured PWM signal exceeds the predetermined duty threshold value, the measurement of the rotation amount of the motor is started.
An image forming apparatus, characterized in that the motor is stopped when the amount of rotation of the motor reaches a preset predetermined amount. The claim is characterized in that the duty threshold value is determined based on a duty of a PWM signal measured by rotating the motor in a rotation direction for driving the image of the photoconductor and a preset set value. 1. The image forming apparatus according to 1. An image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
A motor control means for controlling the distance of the photoconductor by rotating the motor in the direction opposite to the rotation direction for driving the image of the photoconductor to separate the photoconductor from the charging means is provided.
In the separation control, the motor control means
Based on the start of rotation of the motor, the measurement of the amount of rotation of the motor is started, and the duty of the PWM signal that determines the voltage applied to the motor is measured.
Image formation characterized in that the motor is stopped when the rotation amount of the motor reaches a predetermined predetermined amount or when the duty of the measured PWM signal exceeds the preset duty threshold value. Device. A separation holding member that separates the photoconductor from the charging means based on the drive of the photoconductor in the separation control.
Further provided with a movement limiting means for restricting the movement of the separation holding member in the moving direction of the separation holding member for separating the photoconductor from the charging means in the separation control.
The image forming apparatus according to claim 3, wherein the duty threshold value is a value at which the separation holding member does not cause a failure when the separation holding member hits the movement limiting means. An image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
A motor control means for controlling the distance of the photoconductor by rotating the motor in the direction opposite to the rotation direction for driving the image of the photoconductor to separate the photoconductor from the charging means is provided.
In the separation control, the motor control means
Based on the start of rotation of the motor, the measurement of the amount of rotation of the motor is started, and the measurement of the elapsed time from the start of rotation of the motor is started.
An image forming apparatus characterized in that the motor is stopped when the rotation amount of the motor reaches a predetermined amount set in advance, or when the elapsed time reaches a predetermined time set in advance. The image forming apparatus according to claim 5, wherein the motor control means rotates the motor in a rotation direction for driving the image-forming of the photoconductor immediately before performing the separation control. A separation holding member that separates the photoconductor from the charging means based on the drive of the photoconductor in the separation control.
Further provided with a movement limiting means for restricting the movement of the separation holding member in the moving direction of the separation holding member for separating the photoconductor from the charging means in the separation control.
The image forming apparatus according to claim 5 or 6, wherein the predetermined time is a predicted time from the start of rotation of the motor to the time when the separation holding member abuts on the movement limiting means. The image formation according to any one of claims 1 to 7, wherein the rotation speed of the motor is measured based on the count number of a predetermined pulse signal whose frequency changes according to the rotation speed of the motor. Device. A control method for an image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
It has a motor control step of rotating the motor in a direction opposite to the rotation direction for driving the image-forming of the photoconductor to separate the photoconductor from the charging means.
The motor control step is the separation control.
The duty of the PWM signal that determines the voltage applied to the motor is measured and
When the duty of the measured PWM signal exceeds the predetermined duty threshold value, the measurement of the rotation amount of the motor is started.
A control method for an image forming apparatus, which comprises stopping the motor when the amount of rotation of the motor reaches a preset predetermined amount. A control method for an image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
It has a motor control step of rotating the motor in a direction opposite to the rotation direction for driving the image-forming of the photoconductor to separate the photoconductor from the charging means.
The motor control step is the separation control.
Based on the start of rotation of the motor, the measurement of the amount of rotation of the motor is started, and the duty of the PWM signal that determines the voltage applied to the motor is measured.
Image formation characterized in that the motor is stopped when the rotation amount of the motor reaches a predetermined predetermined amount or when the duty of the measured PWM signal exceeds the preset duty threshold value. How to control the device. A control method for an image forming apparatus including a photoconductor, a charging means for charging the photoconductor by contacting the photoconductor, and a motor for driving the photoconductor.
It has a motor control step of rotating the motor in a direction opposite to the rotation direction for driving the image-forming of the photoconductor to separate the photoconductor from the charging means.
The motor control step is the separation control.
Based on the start of rotation of the motor, the measurement of the amount of rotation of the motor is started, and the measurement of the elapsed time from the start of rotation of the motor is started.
A control method for an image forming apparatus, which comprises stopping the motor when the rotation amount of the motor reaches a predetermined amount set in advance, or when the elapsed time reaches a predetermined time set in advance.

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