JP2022115710A - Image forming apparatus - Google Patents

Abstract

To provide an image forming apparatus that can prevent the same part of a photoreceptor from being exposed and prevent a specific part of the photoreceptor from being deteriorated.SOLUTION: A control unit (380) rotates a polygon mirror (330), from the start of start-up processing of detecting, with an optical sensor (360), a laser beam deflected by the polygon mirror (330) before a standby state after the start-up processing is entered, rotates a photoreceptor (410), and before the photoreceptor (410) makes one revolution, stops the photoreceptor (410).SELECTED DRAWING: Figure 2

Description

The present invention relates to an image forming apparatus using a laser scanner.

2. Description of the Related Art Conventionally, in an image forming apparatus using a laser scanner, it is known to prevent the photosensitive member from being unnecessarily exposed and the toner from adhering to the transfer portion when the laser scanner is activated.

For example, Japanese Patent Application Laid-Open No. 2002-200002 describes applying a transfer reverse bias to a portion where toner adheres due to unnecessary exposure to prevent unnecessary toner from adhering to the transfer portion.

JP 2016-071106 A

2. Description of the Related Art In an image forming apparatus using a laser scanner, the polygon mirror is rotated during start-up processing, and the optical sensor detects the beam, so the photoreceptor is unnecessarily exposed. When a specific portion of the photoreceptor is repeatedly exposed to light, photodegradation progresses only in the specific portion.

The technique described in Japanese Patent Application Laid-Open No. 2002-200002 applies a transfer reverse bias to a portion to which toner has adhered due to unnecessary exposure, thereby preventing unnecessary toner from adhering to the transfer portion. However, it does not prevent unnecessary exposure to light.

An object of one aspect of the present invention is to prevent the same portion of the photoreceptor from being exposed to light, thereby preventing deterioration of a specific portion of the photoreceptor.

To solve the above problems, an image forming apparatus according to an aspect of the present invention includes a light source that emits laser light, a polygon mirror that deflects the laser light emitted from the light source, and a laser beam deflected by the polygon mirror. a photoreceptor that is exposed to light; an optical sensor that detects laser light deflected by the polygon mirror; The photoreceptor is rotated from the start of the activation process for detecting the laser light before entering a standby state after the activation process, and the rotation of the photoreceptor is stopped before the photoreceptor makes one rotation.

According to the above configuration, the same portion of the photoreceptor is not exposed, and deterioration of a specific portion of the photoreceptor can be prevented.

The controller may start emitting the laser light from the light source when the rotation speed of the polygon mirror reaches the first target speed.

According to the above configuration, unnecessary exposure to laser light can be further prevented.

The controller may start rotating the photosensitive member when the rotation speed of the polygon mirror reaches the first target speed.

According to the above configuration, unnecessary rotation of the photoreceptor can be prevented.

The image forming apparatus may further include a motor and a clutch that connects the photoreceptor and the motor, and the control unit may connect the clutch after starting rotation of the motor to start rotation of the photoreceptor.

According to the above configuration, the motor can be rotated before rotating the photoreceptor, and the rotation timing of the photoreceptor can be determined by the first clutch.

The control unit may control the motor so that the rotation speed of the photoreceptor from the start of the activation process to before entering the standby state after the activation process is slower than the rotation speed of the photoreceptor during printing. .

According to the above configuration, it is possible to reduce unnecessary consumption of the photoreceptor and the motor.

The image forming apparatus further includes a fixing device that is rotated by a motor, and the control unit transitions from a sleep state in which the heater of the fixing device is not energized to a ready state in which the fixing device is set to a predetermined temperature lower than the fixing temperature. , start-up processing and rotation of the photoreceptor.

According to the above configuration, it is possible to confirm that the scanner has been started normally when preparing for printing.

The control unit may execute the startup process and the rotation of the photoreceptor when the power of the image forming apparatus is turned on.

According to the above configuration, it is possible to confirm that the scanner has been started normally when preparing for printing.

According to one aspect of the present invention, the same portion of the photoreceptor is not exposed, and deterioration of a specific portion of the photoreceptor can be prevented.

1 is a schematic diagram showing the configuration of an image forming apparatus according to an embodiment of the invention; FIG. 2 is a schematic diagram showing the configuration of an exposure unit shown in FIG. 1; FIG. It is a figure which shows an example of the controlled object by a control part. 5 is a flow chart for explaining a processing procedure of start-up processing of the image forming apparatus according to the embodiment of the present invention; 4 is a timing chart showing operations of respective units when the image forming apparatus according to the embodiment of the present invention is started;

<Configuration of Image Forming Apparatus 10>
FIG. 1 is a schematic diagram showing the configuration of an image forming apparatus 10 according to an embodiment of the invention. As shown in FIG. 1 , the image forming apparatus 10 includes a sheet feeding section 100 and an image forming section 200 .

The paper feeding section 100 has a tray 110 , a pickup roller 120 , a conveying roller 130 and a registration roller 140 . The sheets W stored in the tray 110 are picked up one by one by the pickup roller 120, transported by the transport rollers 130, corrected in posture by the registration rollers 140, and transported to the image forming section 200 at a predetermined timing.

The image forming section 200 includes a control section 380 , an exposure section 300 , a process section 400 , a fixing device 500 , a charge application section 610 , a development application section 620 and a transfer application section 630 . The exposure unit 300 irradiates a laser beam L toward a photosensitive drum 410, which will be described later. The configuration of the exposure unit 300 will be detailed later.

The process section 400 has a photosensitive drum 410 , a charging section 420 , a developing section 430 and a transfer roller 440 . The charging section 420 is a scorotron-type charging section having a charging wire 421 and a grid 422 and uniformly charges the surface of the photosensitive drum 410 . When the surface of the photosensitive drum 410 uniformly charged by the charging unit 420 is irradiated with the laser light L from the exposure unit 300 described above, an electrostatic latent image is formed on the surface of the photosensitive drum 410 .

The developing unit 430 develops the electrostatic latent image formed on the surface of the photosensitive drum 410 by supplying developer. Thereby, a developer image is formed on the surface of the photosensitive drum 410 . The transfer roller 440 is arranged to face the photosensitive drum 410, and transfers the developer image formed on the surface of the photosensitive drum 410 onto the sheet W being conveyed. The photosensitive drum 410 is an example of a photoreceptor, the transfer roller 440 is an example of a transfer section, and the sheet W is an example of a transfer target.

The fixing device 500 is arranged downstream of the photosensitive drum 410 in the conveying direction of the sheet W, and fixes the developer image to the sheet W by heat. After that, the sheet W is discharged to a discharge tray 720 formed on the upper surface of the image forming apparatus 10 via discharge rollers 710 .

The charging applying section 610 performs a charging applying operation of applying a voltage VC having the same polarity as the developer in the developing section 430 to the charging wire 421 in accordance with an instruction from the control section 380 . In this charging application operation, the charging applying section 610 detects the grid voltage VG of the grid 422, and the current and the current flowing from the charging applying section 610 to the charging wire 421 so that the grid voltage VG becomes a target value (for example, +800 V). At least one of the values of voltage VC is adjusted.

The development application section 620 applies a development voltage VD having the same polarity as the developer to the development roller 431 of the development section 430 according to an instruction from the control section 380, and sets the development voltage VD to a development target value (for example, +400 V). A development application operation is performed to maintain the voltage.

The transfer application section 630 can switch between forward transfer application operation and reverse transfer application operation according to an instruction from the control section 380 . In the forward transfer applying operation, the transfer applying section 630 applies a forward transfer voltage VTM having a polarity opposite to that of the developer to the transfer roller 440, maintains the forward transfer voltage VTM at a forward transfer target value (eg, −1200 V), and reverses the voltage. In the transfer application operation, a reverse transfer voltage VTP having the same polarity as the developer is applied to the transfer roller 440, and the reverse transfer voltage VTP is maintained at the reverse transfer target value (eg +900V).

<Configuration of Exposure Unit 300>
FIG. 2 is a schematic diagram showing the configuration of the exposure section 300 shown in FIG. As shown in FIG. 2, the exposure unit 300 includes a laser diode (hereinafter referred to as "LD") 310 that emits laser light L, a first lens unit 320, a polygon mirror 330, a polygon motor 340, a second It has a lens unit 350 , a beam detector (hereinafter referred to as “BD”) 360 and a monitor element 370 . LD310 is an example of a light source, and BD360 is an example of an optical sensor. For convenience of explanation, FIG. 2 also shows the control unit 380 and the photosensitive drum 410 .

The polygon mirror 330 is a rotating polygonal mirror having six reflecting surfaces 331 arranged to form side surfaces of a regular hexagonal prism. Polygon mirror 330 is rotationally driven by polygon motor 340 .

The first lens unit 320 is composed of, for example, a collimator lens, converts the laser light L emitted from the LD 310 in accordance with the light emission signal output from the control unit 380 into a light beam, and irradiates the polygon mirror 330 with the light beam. The second lens unit 350 is composed of, for example, an fθ lens, and irradiates the surface of the photosensitive drum 410 with the laser light L emitted from the first lens unit 320 and reflected by the reflecting surface 331 of the polygon mirror 330 .

When the polygon mirror 330 rotates with the rotation of the polygon motor 340, the angle of the reflecting surface 331 with respect to the irradiation direction of the laser light L from the first lens unit 320 changes periodically. positively biased. As a result, a linear electrostatic latent image (hereinafter referred to as an exposure line) is formed by the laser light L on the surface of the photosensitive drum 410 .

The BD 360 is arranged at a position where the laser light L reflected by the reflecting surface 331 is incident when the angle of the reflecting surface 331 with respect to the irradiation direction of the laser light L is a specific angle. The BD 360 outputs a BD signal that is low level at the timing when the laser light L is not incident and high level at the timing when the laser light L is incident. The monitor element 370 is arranged near the LD 310 and outputs a monitor signal corresponding to the amount of the laser light L emitted by the L 310 . This monitor signal is used, for example, for light amount adjustment for adjusting the amount of laser light L emitted by the LD 310 .

<Configuration of control target by control unit 380>
FIG. 3 is a diagram showing an example of objects controlled by the control unit 380. As shown in FIG. In addition to controlling the rotation of the polygon motor 340 and controlling the light emission of the LD 310, the control unit 380 performs detection processing of the BD signal output from the BD 360, rotation control of the motor 450, and connection control of the first clutch 124 and the second clutch 134. , heating control of the fixing heater 501 in the fixing device 500, and the like. Dotted lines between the control unit 380 and each unit indicate electrical signals. Other solid lines indicate transmission of rotation of the motor 450 .

The control unit 380 includes a CPU (Central Processing Unit) 381, a ROM (Read Only Memory) 382, a RAM (Random Access Memory) 383, and an NVM (Non-Volatile Memory) 384 as an example of a storage unit. The control unit 380 performs rotation control of the polygon motor 340 by a rotation signal, light emission control of the LD 310 by a light emission signal, and the like.

The CPU 381 performs processing according to a program read from the ROM 382 and controls each section of the image forming apparatus 10 while storing the results of the processing in the RAM 383 or NVM 384 . Various programs are stored in the ROM 382 , and the various programs include, for example, programs for controlling each section of the image forming apparatus 10 . The RAM 383 is used as a working area and a temporary data storage area when the CPU 381 executes various programs. NVM 384 is a rewritable non-volatile memory.

Rotation of motor 450 is transmitted to first clutch 124 and second clutch 134 by gear 122 . The connection of the first clutch 124 is controlled by the control unit 380 to transmit or block the rotation of the motor 450 to the photosensitive drum 410 . Similarly, the connection of the second clutch 134 is controlled by the control unit 380 to transmit or block the rotation of the motor 450 to the developing unit 430 .

When the power of the image forming apparatus 10 is turned on, the control unit 380 starts startup processing. In this start-up process, the controller 380 causes the LD 310 to emit light and detects the laser light L by the BD 360 . When the laser beam L is detected by the BD 360, the control unit 380 terminates the activation process and transitions to the standby state. In this activation process, the photosensitive drum 410 is exposed because the laser beam L is applied to the photosensitive drum 410 . The controller 380 rotates the photosensitive drum 410 to prevent exposure of the same portion of the photosensitive drum 410 . The rotation of the photosensitive drum 410 is performed from the start of the activation process to the standby state. If printing is to be performed immediately after the start-up process is completed, the photosensitive drum 410 rotates during printing, so there is no particular need to rotate the photosensitive drum 410 .

<Processing Procedure of Startup Processing of Image Forming Apparatus 10>
FIG. 4 is a flowchart for explaining the processing procedure of the startup processing of the image forming apparatus 10. As shown in FIG. First, after the power of the image forming apparatus 10 is turned on, the control section 380 shifts to an error check mode (S1). This error check mode is a mode for checking whether or not the laser light L can be detected by the BD 360 .

After shifting to the error check mode, the controller 380 performs acceleration control of the polygon motor 340 (S2). The polygon motor 340 is composed of, for example, a DC brushless motor or the like, and can obtain an FG (Frequency Generation) signal corresponding to the rotation speed from the back electromotive force of Hall elements or exciting coils.

Next, the controller 380 refers to the rotation speed and determines whether the polygon motor 340 has reached the target rotation speed (first target speed) (S3). If the target rotational speed has not been reached (No in S3), the process returns to step S2 and the subsequent processes are repeated. If the target rotational speed has been reached (Yes in S3), the controller 380 switches the polygon motor 340 from acceleration control to constant speed control (S4). Note that the target rotational speed is a target value at which the rotational speed is constant, not during acceleration.

In the startup mode, the controller 380 rotates the motor 450 to connect the first clutch 124 and rotate the photosensitive drum 410 (S5). It is assumed that the control unit 380 connects the first clutch 124 while the motor 450 is slower than the target rotation speed during printing.

It is also assumed that the control unit 380 disconnects the first clutch 124 to stop the rotation of the photosensitive drum 410 before the photosensitive drum 410 makes one rotation. As a result, even when the activation process is performed again, the exposure position in the circumferential direction of the photosensitive drum 410 changes, so unnecessary exposure to the same portion of the photosensitive drum 410 can be suppressed.

Note that the rotation direction of the photosensitive drum 410 may be forward rotation or reverse rotation. When the control unit 380 reverses the photosensitive drum 410, the toner adhering to the photosensitive drum 410 can be scraped off with a blade.

Next, the controller 380 starts forced lighting of the LD 310 (S6). This is forcibly turning on the LD 310 for a predetermined period of time in order for the BD 360 to detect the laser beam L. FIG. The control unit 380 receives the BD signal output from the BD 360 and determines whether or not the BD 360 has received the laser beam (S7).

If the BD 360 receives the laser beam (Yes in S7), the controller 380 switches the polygon motor 340 to BD control (S8), and ends the process. The BD control is a control in which the rotation speed of the polygon motor 340 is acquired from the BD signal instead of the FG signal and rotated at a constant speed. When the control unit 380 shifts to BD control, it periodically detects whether or not the BD 360 has received the laser beam. , the LD 310 is prevented from emitting light at other timings. Thereby, unnecessary exposure of the photosensitive drum 410 can be suppressed.

Also, if the BD 360 does not receive the laser beam for a predetermined time (No in S7), the control section 380 determines that there is a BD error and performs error processing (S9). Since this error processing is not directly related to the present invention, detailed description will not be given.

<Operation of each unit when the image forming apparatus 10 is started>
FIG. 5 is a timing chart showing the operation of each unit when the image forming apparatus 10 is started. Heating control of the fixing heater 501 is started when the image forming apparatus 10 is started, and the controller 380 starts rotating the motor 450 at the timing T1 when the predetermined temperature is reached. The motor 450 is connected to the fixing device 500, and when the motor 450 is rotated, the fixing device 500 is rotated. As for the waveform of the motor 450 , the vertical axis indicates the rotation speed of the motor 450 . At this timing T1, the polygon motor 340 is not rotating.

At timing T2, when the rotational speed of motor 450 reaches a predetermined value, controller 380 maintains the rotational speed. At this timing T2, the controller 380 starts rotating the polygon motor 340. As shown in FIG. In this state, since the first clutch 124 is disengaged, the photosensitive drum 410 does not rotate.

At timing T3, the rotation speed of the polygon motor 340 reaches the target rotation speed (first target speed), the control unit 380 connects the first clutch 124, rotates the photosensitive drum 410, and the photosensitive drum 410 reaches 1 Before the rotation, the first clutch 124 is disconnected to stop the rotation of the photosensitive drum 410 . The controller 380 controls the rotation of the motor 450 so that the rotational speed of the photosensitive drum 410 at this time is slower than the rotational speed of the photosensitive drum 410 during printing. As a result, unnecessary consumption of the photosensitive drum 410 and the motor 450 can be reduced.

At timing T4, the controller 380 forces the LD 340 to light. When the BD signal is obtained, the control unit 380 terminates the forced lighting, causes the LD 310 to emit light immediately before the timing at which the laser light is incident on the BD 360, and executes control so that the LD 310 does not emit light at other timings. .

At timing T5, the control unit 380 increases the rotational speed of the motor 450. FIG. At this time, the control unit 380 may control the second clutch 134 to rotate the developing roller 431 of the developing unit 430 or may prevent the developing roller 431 from rotating. At timing T6, the rotation speed of the motor 450 reaches the target rotation speed for printing.

Further, when the sleep state in which the fixing heater 501 of the fixing device 500 is not energized is changed to the ready state in which the fixing device 500 is set to a predetermined temperature lower than the printing temperature, the control unit 380 performs start-up processing to 410 may be rotated.

[Example of realization by software]
The functional blocks (in particular, the control unit 380) of the image forming apparatus 10 may be implemented by logic circuits (hardware) formed in an integrated circuit (IC chip) or the like, or may be implemented by software.

In the latter case, the image forming apparatus 10 has a computer that executes program instructions, which are software for realizing each function. This computer includes, for example, one or more processors, and a computer-readable recording medium storing the program. In the computer, the processor reads the program from the recording medium and executes it, thereby achieving the object of the present invention.

For example, a CPU can be used as the processor. As the recording medium, a "non-temporary tangible medium" such as a ROM, a tape, a disk, a card, a semiconductor memory, a programmable logic circuit, or the like can be used. In addition, a RAM or the like for developing the above program may be further provided. Also, the program may be supplied to the computer via any transmission medium (communication network, broadcast wave, etc.) capable of transmitting the program. Note that one aspect of the present invention can also be implemented in the form of a data signal embedded in a carrier wave in which the program is embodied by electronic transmission.

The present invention is not limited to the above-described embodiments, and can be modified in various ways within the scope of the claims. included in the technical scope of

In the above-described embodiment, the LD 340 is forcibly turned on after the photosensitive drum 410 is rotated in the activation process. . Alternatively, the LD 340 may be forcibly turned on while the photosensitive drum 410 is being rotated.

REFERENCE SIGNS LIST 10 image forming apparatus 124 first clutch 310 laser diode 330 polygon mirror 360 beam detector 380 control section 410 photosensitive drum 450 motor 500 fixing device 501 heater

Claims (7)

a light source that emits laser light;
a polygon mirror that deflects the laser beam emitted from the light source;
a photosensitive member exposed by the laser beam deflected by the polygon mirror;
an optical sensor for detecting the laser light deflected by the polygon mirror;
a control unit;
The control unit rotates the polygon mirror and rotates the photoreceptor from the start of activation processing in which the optical sensor detects the laser beam deflected by the polygon mirror to before entering a standby state after the activation processing. and stopping the rotation of the photoreceptor before the photoreceptor makes one rotation. 2. The image forming apparatus according to claim 1, wherein said control section starts emission of laser light from said light source based on the rotation speed of said polygon mirror reaching a first target speed. 3. The image forming apparatus according to claim 2, wherein said controller starts rotating said photoreceptor when the rotation speed of said polygon mirror reaches said first target speed. The image forming apparatus further comprises a motor and a clutch connecting the photoreceptor and the motor,
The image forming apparatus according to any one of claims 1 to 3, wherein after starting rotation of the motor, the control unit engages the clutch and starts rotation of the photoreceptor. The control unit controls the motor so that the rotation speed of the photoreceptor from the start of activation processing to a standby state after the activation processing is slower than the rotation speed of the photoreceptor during printing. 5. The image forming apparatus according to claim 4, wherein: The image forming apparatus further comprises a fixing device rotated by the motor,
The control unit executes the activation process and the rotation of the photoreceptor when transitioning from a sleep state in which the heater of the fixing device is not energized to a ready state in which the fixing device is set to a predetermined temperature lower than a fixing temperature. 6. The image forming apparatus according to claim 4 or 5. The image forming apparatus according to any one of claims 1 to 6, wherein the control section executes the activation process and the rotation of the photoreceptor when power of the image forming apparatus is turned on.

Images