JP7435141B2 - Image forming apparatus and its control method - Google Patents

Description

The present disclosure generally relates to control of an image forming apparatus, and more specifically relates to communication control when a light emitting element emits light.

2. Description of the Related Art In recent years, electrophotographic image forming apparatuses using toner have become widespread. These image forming apparatuses form a toner image on a photoreceptor and transfer the toner image to a medium. In order to form a toner image on the surface of a photoreceptor, an image forming apparatus uses a charging process to form charges on the surface of the photoreceptor, an exposure process to form an electrostatic latent image by irradiating the surface of the photoreceptor with light, Then, a development process is performed to deposit toner on the surface of the photoreceptor.

The above exposure process is executed by the light emission control (control to cause the light emitting element to emit light) of the light emission control section. A control section that controls the entire image forming apparatus transmits parameters related to light emission control and the like to the light emission control section through serial communication.

The light emission control section may malfunction by receiving a signal via serial communication during light emission control, and as a result, the image printed on the medium may deteriorate. Therefore, there is a need for technology to stabilize light emission control.

Regarding the technology for stabilizing light emission control, for example, Japanese Patent Application Laid-Open No. 2019-155807 (Patent Document 1) states that ``The control unit controls a first sheet S on which an image is formed and a continuous control unit from the first sheet S. When forming an image on the second sheet S on which the image is formed, the target light amount stored in the target light amount register DAC is changed between the first sheet S and the second sheet S. Yes, and if serial communication is performed over a period in which the polygon mirror scans the photoreceptor drum multiple times to form an image on the first sheet S, the timing at which the BD signal is output is the start of serial communication. The image forming apparatus discloses an image forming apparatus in which serial communication is set so that the timing of performing APC control and the timing of rewriting the target light amount in the target light amount register DAC do not overlap (see [Summary]).

Japanese Patent Application Publication No. 2019-155807

According to the technology disclosed in Patent Document 1, serial communication processing for the light emission control unit may occur while the light emitting element is emitting light. Therefore, there is a need for a technique for suppressing the occurrence of serial communication processing for the light emission control unit while the light emitting element is emitting light.

The present disclosure has been made in view of the above background, and an object of the present disclosure in one aspect is to provide a technique for suppressing the occurrence of serial communication processing for a light emission control unit while a light emitting element is emitting light. It is in.

An image forming apparatus according to an embodiment includes a photoconductor that forms a toner image, a light-emitting element that exposes the photoconductor, a light-emission control unit that controls light emission of the light-emission element, and a light-emission control unit that controls the light-emission element. and a control unit that transmits a control signal. The control section prohibits the light emission control section from transmitting a signal to the light emission control section when the light emission control section causes the light emitting element to emit light.

In one aspect, the control unit disables a communication function via the communication path based on the fact that the light emission control unit causes the light emitting element to emit light.

In one aspect, the communication path includes a communication path for a clock signal. Disabling the communication function via the communication path includes disabling the clock signal transmission function.

In one aspect, the control unit generates a parameter regarding the timing at which light emission of the light emitting element ends, transmits the parameter to the light emission control unit via the communication path, and the light emission control unit causes the light emission element to emit light based on the parameter. Determine whether or not. The light emission control section includes causing the light emitting element to emit light based on the parameter.

In one aspect, the light emission control section includes an error detection section for detecting an error related to light emission processing. After transmitting the parameters to the light emission control unit, the control unit determines whether the light emission control unit is causing the light emitting element to emit light, and after the light emitting element has finished emitting light, requests the value detected by the error detection unit. A signal is sent to the light emission control unit.

In one aspect, the light emission control unit causes the light emitting element to emit light in order to obtain a horizontal synchronization signal for exposure timing of the light emitting element, and causes the light emitting element to emit light in order to sample the amount of light of the light emitting element.

In one aspect, the parameters include a first counter value for light emission processing to obtain a horizontal synchronization signal and a second counter value for light emission processing to sample the amount of light of the light emitting element.

An image forming apparatus according to another embodiment includes a photoreceptor that forms a toner image, a light emitting element that exposes the photoreceptor, and a first light emission control section and a second light emission control section that execute light emission control of the light emitting element. and a control section that transmits a signal for controlling the light emitting element to each of the first light emission control section and the second light emission control section. The control unit outputs a first selection signal and a second selection signal for selecting a communication destination, and the first light emission control unit outputs the first selection signal through the first communication path. The second light emission control section receives a second selection signal via the second communication path, and the first and second light emission control sections further receive a third selection signal for data transmission/reception. It is connected to the control unit via a communication path. The control unit determines whether each of the first light emission control unit and the second light emission control unit is causing the light emitting element to emit light, and based on the result of the determination, the first selection signal and the second selection signal are output. Among the signals, a select signal that selects the light emission control unit that causes the light emitting element to emit light is set to LOW.

In one aspect, the third communication path includes a communication path for a clock signal. The first communication path and the clock signal communication path are connected to the input port of the first logic circuit, and the communication path on the output port side of the first logic circuit is connected to the first light emission control unit. The first logic circuit outputs a HIGH signal only when the signals on both the first communication path and the clock signal communication path are HIGH, and the first logic circuit outputs a HIGH signal only when the signals on both the first communication path and the clock signal communication path are HIGH. The signal communication path is connected to the input port of the second logic circuit, and the communication path on the output port side of the second logic circuit is connected to the second light emission control section. The logic circuit outputs a HIGH signal only when the signals on both the second communication path and the clock signal communication path are HIGH.

In one aspect, the control unit generates parameters regarding the timing of ending light emission of the light emitting element, transmits the parameters to each of the first and second light emission control units via the third communication path, and transmits the parameters to each of the first and second light emission control units. Each of the second light emission control sections causes the light emitting element to emit light based on the parameter, and determines whether each of the first light emission control section and the second light emission control section causes the light emitting element to emit light. The method includes determining, based on the parameters, which light emission control section causes the light emitting element to emit light.

In one aspect, each of the first and second light emission control sections includes an error detection section for detecting an error related to light emission processing. After transmitting the parameter to either the first or second light emission control unit, the control unit determines whether the light emission control unit to which the parameter is transmitted is causing the light emitting element to emit light, and After the precontrol unit finishes emitting light from the light emitting element, a signal for requesting the value detected by the error detection unit is transmitted to the light emission control unit to which the parameters are transmitted.

In one aspect, the first and second light emission control units cause the light emitting element to emit light in order to obtain a horizontal synchronization signal for exposure timing of the light emitting element, and cause the light emitting element to emit light in order to sample the amount of light of the light emitting element. let

In one aspect, the parameters include a first counter value for light emission processing to obtain a horizontal synchronization signal and a second counter value for light emission processing to sample the amount of light of the light emitting element.

According to another embodiment, a method of controlling an image forming apparatus is provided. This control method includes the step of prohibiting the light emission control section from transmitting a signal when the light emission control section causes the light emitting element to emit light.

In one aspect, the control method further includes the step of disabling a communication function via the communication channel based on the fact that the light emission control unit causes the light emitting element to emit light.

In one aspect, the communication path includes a communication path for a clock signal. In the control method, disabling a communication function via the communication path includes disabling a clock signal transmission function.

In one aspect, the control method includes the steps of: generating a parameter regarding the timing of ending light emission of the light emitting element; transmitting the parameter to the light emission control unit via a communication path; and controlling the light emission control unit based on the parameter. The method includes a step of determining whether or not the light emitting element is emitting light, and a step of causing the light emitting element to emit light based on a parameter.

In one aspect, the control method includes a step of determining whether or not the light emitting element is causing the light emitting element to emit light after transmitting a parameter to the light emitting controller, and a step of determining whether the light emitting element is causing the light emitting element to emit light after transmitting parameters to the light emitting controller. The method further includes the step of transmitting a signal to the light emission control section to request the value detected by the provided error detection section.

In one aspect, the parameters include a first counter value for light emission processing to obtain a horizontal synchronization signal for exposure timing of the light emitting element, and a second counter value for light emission processing to sample the amount of light of the light emitting element. including.

A method for controlling an image forming apparatus according to another embodiment includes the steps of determining whether each of a first light emission control section and a second light emission control section is causing a light emitting element to emit light, and based on the result of the determination. The first select signal is transmitted to the first light emission control unit via the first communication path, and the second select signal is transmitted to the second light emission control unit via the second communication path. The method includes a step of turning LOW a select signal that selects a light emission control section that causes a light emitting element to emit light.

According to one embodiment, it is possible to suppress the occurrence of serial communication processing for the light emission control unit while the light emitting element is emitting light.

These and other objects, features, aspects, and advantages of this disclosure will become apparent from the following detailed description of this disclosure, taken in conjunction with the accompanying drawings.

1 is a diagram illustrating an example of an image forming apparatus 100 according to an embodiment. FIG. 2 is a schematic diagram illustrating a part of a control system related to light emission control of the image forming apparatus 100. FIG. 2 is a schematic diagram showing an example of a configuration for controlling a laser diode 213 in a light emission control section 211. FIG. 2 is a side view showing an example of the configuration of a print head section 210. FIG. 2 is a top view showing an example of the configuration of a print head section 210. FIG. FIG. 7 is a diagram showing an example of the state of each light emission and signal when light emission of the laser diode 213 and serial communication occur simultaneously. FIG. 6 is a diagram illustrating an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. 5. FIG. FIG. 2 is a first schematic diagram showing an example of a print head section 210 including a plurality of light emission control sections 211. FIG. 9 is a diagram illustrating an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. 8. FIG. 3 is a second schematic diagram showing an example of a print head section 210 including a plurality of light emission control sections 211. FIG. 11 is a diagram illustrating an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. 10. FIG. 3 is a flowchart illustrating an example of print processing in the image forming apparatus 100. 3 is a flowchart illustrating an example of image stabilization processing in the image forming apparatus 100. FIG. 3 is a diagram showing a list of types of stabilization processing.

Hereinafter, embodiments of the technical idea according to the present disclosure will be described with reference to the drawings. In the following description, the same parts are given the same reference numerals. Their names and functions are also the same. Therefore, detailed descriptions thereof will not be repeated.

<A. Overview of image forming device>
FIG. 1 is a diagram showing an example of an image forming apparatus 100 according to the present embodiment. According to the present embodiment, there is provided an image forming apparatus 100 that suppresses communication processing to the light emission control section during light emission control by the light emission control section. An overview of the hardware configuration of image forming apparatus 100 will be described with reference to FIG. 1. Image forming apparatus 100 includes a print engine 110, a document reading section 120, and an operation panel 60.

The print engine 110 includes an imaging unit 10 , an intermediate transfer belt 12 , a fixing section 22 , a paper feed section 30 , a delivery roller 32 , a conveyance roller 34 , a registration roller 36 , a control section 50 , and a power supply section 52 Equipped with. The print engine 110 performs print processing on the medium in the paper feed section 30 . The delivery roller 32 transports the medium from the paper feed section 30. Further, the conveyance roller 34 conveys the medium toward the intermediate transfer belt 12 .

The imaging unit 10 includes imaging units 10C, 10M, 10Y, and 10K that form cyan (C), magenta (M), yellow (Y), and key plate (K) toner images, respectively. The imaging units 10C, 10M, 10Y, and 10K include a photoconductor 1, a charging section (not shown), a developing section (not shown), a cleaning section (not shown), and an intermediate transfer member contact roller (not shown). (not shown).

The exposure section 3 is common to the imaging units 10C, 10M, 10Y, and 10K. In one aspect, each of the imaging units 10C, 10M, 10Y, 10K may include an individual exposure section 3. In the following description, it is assumed that the exposure section 3 is common to each of the imaging units 10C, 10M, 10Y, and 10K.

Imaging unit 10 and intermediate transfer belt 12 form toner images that are transferred to media. The charging unit uniformly charges the surface of the photoreceptor 1. The exposure unit 3 forms an electrostatic latent image on the surface of the photoreceptor 1 by exposing the surface of the photoreceptor 1 to light according to a designated image pattern by laser writing or the like. The developing section develops the electrostatic latent image formed on the photoreceptor 1 as a toner image.

The registration roller 36 adjusts the conveyance timing of the medium before the intermediate transfer belt 12. Intermediate transfer belt 12 transfers the toner image onto a medium. The fixing unit 22 performs a fixing process on the medium. Finally, the media is ejected to an ejection tray.

The toner image formed on the surface of the photoreceptor 1 is transferred to the intermediate transfer belt 12 by an intermediate transfer member contact roller. Toner images are sequentially transferred from each photoreceptor 1 onto the intermediate transfer belt 12, and the four color toner images are superimposed. The superimposed toner images are transferred from intermediate transfer belt 12 to a medium.

The document reading unit 120 reads a document and outputs the reading result as an input image to the print engine 110. The image scanner 122 scans a document placed on a platen glass and transmits the generated image data to the control unit 50. Automatic document feeder 126 continuously scans documents placed on document feed table 124 . The documents placed on the document feed table 124 are fed one by one by a delivery roller (not shown) and sequentially scanned by an image sensor disposed within the image scanner 122 or the automatic document feeder 126. The scanned document is discharged onto the document discharge table 128. The control unit 50 controls the entire image forming apparatus 100. The power supply section 52 is connected to an AC power source and supplies power to the image forming apparatus 100. The power supply section 52 includes a rectifier circuit therein, and can convert alternating current supplied from an alternating current power source into direct current, and supply direct current to some or all of the circuits in the image forming apparatus 100.

Operation panel 60 includes a display section (not shown) and an operation section (not shown). The display unit includes a liquid crystal monitor, an organic EL (Electro Luminescence) monitor, and the like. A liquid crystal monitor, an organic EL monitor, or the like includes a touch sensor, and can display an operation menu and receive touch input from a user. The operation unit includes a plurality of buttons and can receive input from the user like a touch panel. The operation panel 60 transmits the received input to the control unit 50.

FIG. 2 is a schematic diagram illustrating a part of a control system related to light emission control of the image forming apparatus 100. Each configuration shown in FIG. 2 may be realized by an electrical circuit and hardware used in combination with the electrical circuit. The control unit 50 includes an image processing unit 203 and a light emission mode control unit 204. Further, the control unit 50 is connected to the humidity sensor 216. The print head section 210 includes a light emission control section 211 , a polygon motor 212 , a laser diode 213 , a light sensor 214 , and a dust sensor 215 .

The control unit 50 includes a CPU (Central Processing Unit) (not shown), a RAM (Random Access Memory) (not shown), and a ROM (Read Only Memory) (not shown). The CPU executes or references various programs and data loaded into the RAM. In one aspect, the CPU may be a built-in CPU, an FPGA (Field-Programmable Gate Array), or a combination thereof. The CPU can execute programs for realizing various functions of the image forming apparatus 100.

The RAM stores programs executed by the CPU and data referenced by the CPU. In one aspect, the RAM may be implemented by DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory).

ROM is a non-volatile memory and may store programs executed by the CPU. In that case, the CPU executes the program read from the ROM to the RAM. In one aspect, the ROM may be implemented by an Erasable Programmable Read Only Memory (EPROM), an Electrically Erasable Programmable Read-Only Memory (EEPROM), or a flash memory.

The image processing unit 203 transmits an image signal to the light emission control unit 211. The image signal may be generated based on image data read by the image scanner 122 or image data acquired from an external device via a communication unit (not shown) included in the image forming apparatus 100. The light emission control unit 211 causes the laser diode 213 to form an electrostatic latent image on the surface of the photoreceptor 1 based on the image signal.

The light emission mode control unit 204 provides information regarding synchronous light emission for obtaining an SOS (Start of Scan) signal, which is a horizontal synchronization signal for the exposure timing of the laser diode (light emitting element) 213, and for adjusting the light intensity of the laser diode 213. Information regarding SH (Sample Hold) light emission is transmitted to the light emission control unit 211. This information includes counter values for defining the generation timing and end timing of each signal.

The SOS signal may be used to determine when to start emitting light. The SOS signal is generated when the optical sensor 214 detects synchronous light emission (hereinafter referred to as "SOS light emission") for obtaining the SOS signal. The SH light emission is light emission for adjusting the amount of light irradiated onto the photoreceptor 1. An optical sensor (not shown) for detecting the backlight of the laser diode 213 detects SH light emission and transmits a signal based on the detected value to the light emission control section 211 or the control section 50. The light emission control section 211 or the control section 50 can correct the light amount of the laser diode 213 based on the detected value of SH light emission. In some aspects, optical sensor 214 may detect SH emission.

In a certain aspect, the image processing unit 203 and the light emission mode control unit 204 may be realized as separate hardware included in the control unit 50. In other aspects, the image processing unit 203 and the light emission mode control unit 204 may be implemented as a program executed by the CPU of the control unit 50.

The light emission control section 211 controls each piece of hardware (polygon motor 212, laser diode 213, etc.) of the print head section 210. The polygon motor 212 is a motor for driving a polygon mirror for reflecting the laser emitted by the laser diode 213. The laser diode 213 irradiates the photoreceptor 1 with a laser beam to form an electrostatic latent image on its surface. By controlling the polygon motor 212 and the laser diode 213, the light emission control unit 211 can irradiate a laser beam onto any location on the surface of the photoreceptor 1 of each color.

The optical sensor 214 detects the laser light emitted by the laser diode 213. The optical sensor 214 transmits a signal indicating the detected amount of light to the light emission control section 211. In some aspects, optical sensor 214 may detect laser light reflected by a polygon mirror.

The dust sensor 215 detects dust around the laser head section 210. The dust sensor 215 transmits a signal indicating the amount of detected dust to the light emission control unit 211. In one aspect, the light emission control unit 211 may output an error to the control unit 50 when the amount of dust is above a certain level.

Humidity sensor 216 may be installed inside or outside the housing of image forming apparatus 100. The humidity sensor 216 detects the humidity around the humidity sensor 216. Humidity sensor 216 transmits a signal related to detected humidity to control unit 50. The control unit 50 can adjust various parameters (charging voltage, amount of light, amount of toner, etc.) of the charging process, exposure process, and development process of the photoreceptor 1 depending on the humidity.

<B. Light emission control and communication for light emission control>
FIG. 3 is a schematic diagram showing an example of a configuration for controlling the laser diode 213 in the light emission control section 211. Referring to FIG. 3, the internal configuration of the light emission control section 211, light emission control by the light emission control section 211, and communication between the control section 50 and the light emission control section 211 will be described.

(B-1. Configuration of light emission control unit 211)
The light emission control section 211 includes an OR circuit 311, a laser diode drive section 312, a laser diode 213, a timing signal generation section 314, a light amount correction section 317, a reference clock generation section 319, and an error detection section 320. . Timing signal generator 314 includes a counter value memory 315 and a counter 316. The light amount correction section 317 includes a correction value memory 318. The control section 50 and the light emission control section 211 are connected via an image signal line 302, a serial signal line 303, and an SOS signal line 304.

OR circuit 311 receives two input signals and outputs one output signal. The first input signal is an image signal output from the image processing unit 203 via the image signal line 302. The second input signal is a timing signal output from the timing signal generator 314. When the OR circuit 311 receives the input of the image signal, it outputs the same signal as the image signal to the laser diode drive section 312. Further, upon receiving the input of the timing signal, the OR circuit 311 outputs the same signal as the timing signal to the laser diode drive section 312.

Laser diode drive section 312 drives laser diode 213 based on the signal output from OR circuit 311. For example, upon receiving the image signal, the laser diode drive unit 312 controls the laser diode 213 to form an electrostatic latent image on the surface of the photoreceptor 1 based on the image signal. Further, upon receiving the timing signal, the laser diode drive unit 312 controls the laser diode 213 to perform SOS light emission or SH light emission. The course of the laser beam output from the laser diode 213 is adjusted by a polygon mirror 321.

The timing signal generating section 314 measures the execution timing of the SOS light emission or the SH light emission, and outputs a timing signal to the OR circuit 311 in accordance with the execution timing of the SOS light emission or the SH light emission. Counter value memory 315 holds counter values for each signal. For example, the counter value memory 315 holds matching settings for each signal in the timer, reset timing of the timer, and the like. Counter 316 is a counter for a timer. The timing signal generator 314 counts up or down the count value of the counter 316. The timing signal generation unit 314 compares the count value of the counter 316 and the count value of the matching settings for each signal in the counter value memory 315, and generates a timing signal if they match.

The light emission mode control unit 204 transmits a counter value related to SOS light emission or SH light emission to the light emission control unit 211 via the serial signal line 303. In one aspect, these counter values may include matching settings for SOS emissions, matching settings for SH emissions, and timer reset timing. The light emission control unit 211 stores these received counter values in the counter value memory 315. The control unit 50 uses these counter values to detect the period during which the serial communication function is disabled. The details will be described later.

Note that the serial signal line 303 may include, for example, three signal lines: a serial clock signal line, a data input signal line, and a data output signal line. The serial clock signal line transmits a clock in serial communication. Serial communication data is transmitted and received at the timing of the clock. In one aspect, the control unit 50 generates a clock to be transmitted to the serial clock signal line.

The data input signal line transmits data from the slave (light emission control section 211) to the master (control section 50). The light emission mode control section 204 receives data from the light emission control section 211 via the data input signal line.

The data output signal line transmits data from the master (control unit 50) to the slave (light emission control unit 211). The light emission mode control section 204 transmits data to the light emission control section 211 via the data output signal line. For example, the light emission mode control unit 204 transmits counter values regarding SOS light emission and SH light emission to the light emission control unit 211 via the data output signal line.

The light amount correction section 317 transmits a light amount correction signal to the laser diode drive section 312. The light amount correction unit 317 generates a light amount correction signal based on the correction value memory 318. The light amount correction section 317 can store the correction value in the correction value memory 318 based on the signals from the light emission mode control section 204 and the timing signal generation section 314. The light emission control unit 211 may rewrite the correction value memory 318 based on the light amount correction value signal acquired from the control unit 50 via the serial signal line 303.

The reference clock generator 319 generates a reference clock for a timer used by the timing signal generator 314. The reference clock generator 319 can adjust the start position or end position of the reference clock based on the SOS signal output by the optical sensor 214 when detecting SOS light emission. The SOS signal is transmitted to the reference clock generation section 319 and the control section 50 via the SOS signal line 304.

The error detection section 320 detects various errors occurring in the print head section 210. Examples of various errors include overcurrent to the laser diode 213, voltage drop in the light emission control unit 211, malfunction of the counter 316, and the like. When the error detection unit 320 detects these errors, the corresponding bit in the built-in register changes from 0 to 1. The control unit 50 reads error information stored in the error detection unit 320 via the serial signal line 303. More specifically, the control unit 50 transmits an error read request to the light emission control unit 211 via the serial signal line 303, and receives error information from the light emission control unit 211.

(B-2. Occurrence timing of each light emission)
Next, the timing at which the laser diode 213 emits light will be explained. As described above, during the exposure process, the print head unit 210 performs SOS emission, SH emission, and emission for forming an electrostatic latent image.

In order to form one image on the surface of the photoreceptor 1, the print head unit 210 repeats each of SOS light emission, SH light emission, and light emission that forms an electrostatic latent image multiple times. The print head unit 210 forms part of an electrostatic latent image on the surface of the photoreceptor 1 line by line. The print head unit 210 repeatedly forms a part of the electrostatic latent image on the surface of the photoconductor 1 line by line, thereby finally forming an electrostatic latent image of one image on the surface of the photoconductor 1. . SOS light emission, SH light emission, and light emission that forms an electrostatic latent image are generated in units of lines. For example, when the print head unit 210 forms part of an electrostatic latent image on the surface of the photoreceptor 1 line by line 1000 times, SOS light emission, SH light emission, and light emission that forms the electrostatic latent image also occur 1000 times. . The print head unit 210 repeatedly executes each light emission in the order of, for example, light emission for forming an electrostatic latent image, SOS light emission, and SH light emission.

(B-3. Communication occurring between control unit 50 and light emission control unit 211)
The communication related to light emission control that occurs between the control section 50 and the light emission control section 211 includes at least the following first to fourth communications.

The first communication is communication of counter values regarding SOS light emission and SH light emission. The communication is performed via the serial signal line 303. Based on the first communication, the light emission control section 211 can rewrite the counter value memory 315 of the timing signal generation section 314 to count the timing of SOS light emission or SH light emission. The print head unit 210 performs SOS light emission and SH light emission before and after light emission to form an electrostatic latent image on the surface of the photoreceptor 1 .

The second communication is image signal communication. The control unit 50 transmits an image signal to the light emission control unit 211 based on the acquisition of the image data and the print command. The image signal is a signal for causing the print head section 210 to form an electrostatic latent image on the surface of the photoreceptor 1. The light emission control unit 211 executes light emission to form an electrostatic latent image on the surface of the photoreceptor 1 based on the second communication.

The third communication is communication of the detection value of the optical sensor 214. When the optical sensor 214 detects the laser light from the laser diode 213, it transmits a detection signal to the reference clock generation section 319 and the control section 50 via the SOS signal line 304. The detection signal transmitted from optical sensor 214 may include at least an SOS signal. The reference clock generation section 319 can adjust the reference clock based on the SOS signal when SOS light emission is detected.

The fourth communication is for reading error information. The control unit 50 communicates with the light emission control unit 211 via the serial signal line 303 in order to read error information from the error detection unit 320. The fourth communication may be performed immediately after the first communication.

When the first communication and the fourth communication (serial communication) occur among the above four types of communication, the light emission control unit 211 rewrites the built-in register memory for serial communication all at once, so a large amount of flip-flop operate the pull-up circuit. As a result, the light emission control unit 211 temporarily consumes a large amount of power. If serial communication occurs at the same time as light emission control, it may cause a voltage drop in the light emission control section 211, causing a malfunction of the counter 316 or the like. If a malfunction of the counter 316 occurs, an electrostatic latent image may not be properly formed on the surface of the photoreceptor 1, and the quality of the printed image may deteriorate.

(B-4. Timing when light emission control and serial communication occur simultaneously)
Next, an example of timing at which light emission control and serial communication can occur simultaneously will be described. The first communication occurs only once for each job. The first communication is completed before execution of light emission control. After the first communication is completed, printhead unit 210 performs light emission to form an electrostatic latent image. Further, the fourth communication may occur immediately after the first communication. When light emission for forming an electrostatic latent image and fourth communication occur simultaneously, a large amount of power is consumed in the light emission control unit 211, and a voltage drop may occur.

Therefore, as described above, in the image forming apparatus 100 according to the present embodiment, when the light emission control section 211 is executing the light emission control, the control The serial communication function of the unit 50 is disabled. The control unit 50 executes serial communication only when the light emission control unit 211 is not executing light emission control. For example, the control unit 50 executes the fourth communication for reading error information from the error detection unit 320 only when the light emission control unit 211 is not executing the light emission control, such as after completion of the issuing control.

More specifically, the light emission mode control unit 204 generates counter values regarding SOS light emission and SH light emission, and transmits these counter values to the light emission control unit 211. Therefore, the light emission mode control unit 204 can detect the timing at which the light emission control unit 211 completes light emission control (the light emitting element completes light emission) based on the counter values regarding SOS light emission and SH light emission. The control unit 50 disables the serial communication function of the control unit 50 from the start timing to the completion timing of the light emission control of the light emission control unit 211 (from the start to the completion of light emission of the light emitting element). It is possible to prevent the occurrence of the voltage drop described above by prohibiting the occurrence of serial communication that occurs during the process. In one aspect, the control unit 50 may disable the function of the serial clock port. In other aspects, the control unit 2110 may disable the functions of the serial clock port, data input port, and data output port.

As described above, the image forming apparatus 100 according to the present embodiment disables the serial communication function of the control section 50 during light emission control based on various counter values set in the light emission control section 211. With this function, the image forming apparatus 100 prevents serial communication and light emission control from occurring simultaneously. As a result, a voltage drop does not occur in the light emission control unit 211, and malfunctions of the counter 316 due to the voltage drop also do not occur, and the quality of the printed image is improved.

<C. Hardware configuration of print head >
Next, with reference to FIGS. 4 and 5, the manner in which laser light is reflected at the print head section 210 will be described. FIG. 4 is a side view showing an example of the configuration of the print head section 210. In the example shown in FIG. 4, the laser beam reflected by the polygon mirror 321 passes through the fθ lens 403 and enters a reflecting mirror for reflecting the laser beam onto the photoreceptor 1 of each color.

Reflection mirrors 404Y and 405Y reflect the laser beam onto the yellow photoreceptor 1. Reflection mirrors 404M and 405M reflect the laser beam onto the magenta photoreceptor 1. Reflection mirrors 404C and 405C reflect the laser beam onto the cyan photoreceptor 1. The reflecting mirror 404K reflects the laser beam onto the photoreceptor 1 of the key plate (black).

FIG. 5 is a top view showing an example of the configuration of the print head section 210. In the image forming apparatus 100 equipped with a full-color printing function, the print head unit 210 includes light emitting elements (lasers) for each color of yellow (Y), magenta (M), cyan (C), and key plate (black) (K). diode 213). Each of the laser beams emitted from each light emitting element is focused by each of the collimator lenses 502Y, 502M, 502C, and 502K. Each of the focused laser beams is focused on a reflecting mirror 504 by each of reflecting mirrors 503Y, 503M, 503C, and 503K installed with steps. Reflection mirror 504 guides each laser beam to polygon mirror 321. A portion of the laser light reflected from the polygon mirror 321 enters the optical sensor 214 via the reflective mirror 511.

<D. Light emission and signal timing>
Next, with reference to FIGS. 6 and 7, the timing of light emission from the laser diode 213 and the generation of serial communication signals will be described. FIG. 6 is a diagram showing an example of the state of each light emission and signal when light emission of the laser diode 213 and serial communication occur simultaneously. Communications (SK, DI, DO) are a serial clock signal, data input signal, and data output signal.

The light emission control unit 211 executes light emission processing 601, 602, and 603 three times. Each light emission process includes SOS light emission and SH light emission. Actually, the light emission control unit 211 executes light emission processing for forming an electrostatic latent image on the surface of the photoreceptor 1 during the light emission processing 601 , 602 , and 603 . For example, between the light emission processing 601 and the light emission processing 602, the light emission control unit 211 can perform light emission processing for forming one line of electrostatic latent image on the surface of the photoreceptor 1.

In the example shown in FIG. 6, serial communication occurs at the timing of the third light emission process 603. As a result, the rewriting process of the communication register inside the light emission control section 211 and the light emission of the laser diode 213 occur simultaneously, and a voltage drop in the light emission control section 211 occurs. At that time, the counter 316 malfunctions, and the light emission control unit 211 no longer executes the SOS light emission and SH light emission processing that was originally supposed to be executed. is also skipped. As a result, the quality of the printed image deteriorates.

FIG. 7 is a diagram showing an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. The period 703 is a period during which the light emission control unit 211 is executing light emission control. In other words, this period is a period during which the image forming process is being executed by the light emission control section 211. The control unit 50 disables the serial communication function of the control unit 50 during the period 703. Therefore, serial communications 701 and 702 between the control unit 50 and the light emission control unit 211 occur only before and after the period 703. As a result, a voltage drop in the light emission control unit 211 does not occur, and the quality of the printed image does not deteriorate.

<E. Application to other device configurations>
The above disclosure is also applicable to the plurality of light emission control units 211. With reference to FIGS. 8 to 11, a method for stopping serial communication of the control unit 50 while the plurality of light emission control units 211 are controlling light emission will be described.

FIG. 8 is a first schematic diagram showing an example of the print head unit 210 including a plurality of light emission control units 211. The example shown in FIG. 8 differs from the example shown in FIG. 5 in that a plurality of light emission control units 211A and 211B execute light emission control. For example, the light emission control unit 211A forms electrostatic latent images of yellow (Y) and cyan (C), and the light emission control unit 211B forms electrostatic latent images of magenta (M) and key plate (black) (K). Image formation may be performed. In this way, the print head section 210 can form an electrostatic latent image on the surface of the photoreceptor 1 at high speed by including the plurality of light emission control sections 211A and 211B.

In the example of FIG. 8, the control unit 50 includes at least two select ports (not shown) for specifying communication destinations for serial communication. The first select port is connected to the light emission control section 211A via the signal line 801A. The second select port is connected to the light emission control section 211B via the signal line 801B.

The control unit 50 determines the communication destination by setting one of the outputs (select signal) of the first select port or the second select port to HIGH. For example, when the control unit 50 sets the output of the first select port to HIGH, the light emission control unit 211A determines that its own device has been selected as a communication destination, and takes in the signal transmitted from the control unit 50. Conversely, the output of the second select port remains LOW, and the light emission control unit 211B determines that its own device is not selected as a communication destination, and does not take in the signal transmitted from the control unit 50.

The control unit 50 performs each light emission control by not setting the select port of the light emission control unit 211 during light emission control to HIGH based on the counter values of the SOS light emission and SH light emission transmitted to each of the light emission control units 211A and 211B. It is possible to prevent light emission processing and serial communication from occurring simultaneously in the units 211A and 211B.

In a certain aspect, the control unit 50 may realize the above functions by using conditional branching or the like using software. In another aspect, the control unit 50 may disable the output of each select port from going HIGH by rewriting the register of each select port. In another aspect, when both of the light emission control sections 211A and 211B are in the process of emitting light, the control section 50 may disable the serial communication function itself.

FIG. 9 is a diagram showing an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. 8. The SK signal, DI signal, DO signal, and CS signal (SC1, SC2 signals) are a serial clock signal, a data input signal, a data output signal, and a select signal, respectively.

A period 903 is a period during which the light emission control units 211A and 211B are executing light emission control. In other words, this period is a period during which the image forming process of the print job is being executed. The control unit 50 disables the serial communication function of the control unit 50 during the period 903. Alternatively, the control unit 50 sets the output of the select port to LOW for selecting the light emission control unit 211 that is executing the light emission control. Therefore, serial communications 901 and 902 between the control unit 50 and the light emission control units 211A and 211B occur only before and after the period 903. As a result, no voltage drop occurs in either of the light emission control units 211A, 211B, and no quality deterioration of the printed image occurs.

FIG. 10 is a second schematic diagram showing an example of the print head section 210 including a plurality of light emission control sections 211. The example shown in FIG. 10 differs from the above-described configuration in that the plurality of light emission control units 211A and 211B execute light emission control, and the control unit 50 disables the serial communication function of the control unit 50 by hardware. is different.

For example, the light emission control unit 211A forms electrostatic latent images of yellow (Y) and cyan (C), and the light emission control unit 211B forms electrostatic latent images of magenta (M) and key plate (black) (K). Image formation may be performed.

In the example of FIG. 10, the signal line 1001 includes a data input signal line and a data output signal line in serial communication. Signal line 1002 is a serial clock communication line. The signal line 1003A is a signal line connected to the first select port for selecting the light emission control unit 211A. The signal line 1003B is a signal line connected to the second select port for selecting the light emission control section 211B.

Each of signal line 1002 and signal line 1003A is connected to an input port of AND circuit 1004A. Each of signal line 1002 and signal line 1003B is connected to an input port of AND circuit 1004B.

A signal line on the output side of the AND circuit 1004A is connected to a serial clock signal input port of the light emission control section 211A. The signal line on the output side of the AND circuit 1004B is connected to the serial clock signal input port of the light emission control section 211B.

With the above configuration, the signal of the select port for selecting each light emission control section 211A, 211B can be a signal for controlling enabling and disabling of the clock signal. More specifically, when the control unit 50 sets the output of the first select port to HIGH and the output of the second select port to LOW, when the control unit 50 generates a serial clock, the AND circuit 1004A outputs a serial clock, but AND circuit 1004B does not output a serial clock. In this way, in the example of FIG. 10, by blocking the serial clock to the light emission control section 211 that is not selected by the control section 50 by the hardware configuration, the serial clock to the light emission control section 211 that is under light emission control can be more reliably controlled. Communication may be prevented.

FIG. 11 is a diagram showing an example of the state of each light emission and signal when the serial communication disabling function of the control unit 50 is used in the configuration of FIG. 10. The SK1 signal is a serial clock signal output from the AND circuit 1004A to the light emission control section 211A. The SK2 signal is a serial clock signal output from the AND circuit 1004B to the light emission control section 211B.

A period 1103 is a period during which the light emission control units 211A and 211B are executing light emission control. In other words, this period is a period during which the image forming process of the print job is being executed. The control unit 50 disables the serial communication function of the control unit 50 during the period 1103. Alternatively, the control unit 50 disables the select port for selecting the light emission control unit 211 that is executing the light emission control, and forcibly cuts off the serial clock signal to the light emission control unit 211 that is not selected. Therefore, serial communications 1101 and 1102 between the control unit 50 and the light emission control units 211A and 211B occur only before and after the period 1103. As a result, no voltage drop occurs in either of the light emission control units 211A, 211B, and no quality deterioration of the printed image occurs.

<F. Internal processing>
Next, internal processing related to light emission control of the image forming apparatus 100 will be described with reference to FIGS. 12 to 14. In one aspect, the CPU of the control unit 50 loads a program for performing the processes shown in FIGS. 12 and 13 from the ROM of the control unit 50 or another storage medium into the RAM of the control unit 50, and executes the program. Good too. In other aspects, part or all of the processing may be implemented as a combination of circuit elements configured to perform the processing.

FIG. 12 is a flowchart illustrating an example of print processing in the image forming apparatus 100. In step S1210, the control unit 50 transmits the SOS light emission start counter value, the SOS light emission end counter value, the SH light emission start counter value, and the SH light emission end counter value to the light emission control unit 211. The light emission control unit 211 stores each of these counter values in the counter value memory 315.

In step S1220, the control unit 50 transmits a light emission control start command to the light emission control unit 211. In step S1230, the control unit 50 stops the serial communication clock to the light emission control unit 211. More specifically, the control unit 50 disables the function of the port that outputs the serial clock. In one aspect, the control unit 50 may also disable the serial communication data input port function and data output port function.

In step S1240, the control unit 50 starts printing processing. The control unit 50 drives actuators such as the conveyance roller 34, the imaging unit 10, and the fixing unit 22. In step S1250, the light emission control unit 211 executes light emission control. The light emission control includes formation of an electrostatic latent image on the surface of the photoreceptor 1, SOS light emission, SH light emission, and the like.

In step S1260, the control unit 50 determines whether the printing process has ended. If the control unit 50 determines that the printing process has ended (YES in step S1260), it moves the control to step S1270. If not (NO in step S1260), control unit 50 moves control to step S1250.

In step S1270, the control unit 50 determines whether the end sequence processing has ended. When the control unit 50 determines that the end sequence processing has ended (YES in step S1270), the control section 50 moves the control to step S1280. If not (NO in step S1270), control unit 50 repeats the process of step S1270.

In step S1280, the control unit 50 starts a communication clock to the light emission control unit 211. More specifically, the control unit 50 enables the function of the port that outputs the serial clock. In one aspect, the control unit 50 may also enable the function of a data input port and the function of a data output port of serial communication. In step S1290, the control unit 50 transmits a light emission control stop command to the light emission control unit 211. In some aspects, the order of execution of step S1280 and step S1290 may be reversed.

FIG. 13 is a flowchart illustrating an example of image stabilization processing in the image forming apparatus 100. The image forming apparatus 100 executes image stabilization processing during a period when printing processing is not executed, and adjusts the amount of light emitted from the laser diode 213.

Each process of steps S1310 to S1330, S1370, and S1380 is the same as each process of steps S1210 to S1230, S1270, and S1280, so the description of these steps will not be repeated.

In step S1340, the control unit 50 starts image stabilization processing. The image stabilization process includes, for example, forming a test toner patch on the photoconductor 1 and adjusting the exposure amount and toner supply amount of the photoconductor 1. In step S1350, IDC (Image Density Control) sensor calibration control is performed. In step S1360, the control unit 50 executes adhesion amount control, laser diode light amount control, resist control, and γ correction control. The adhesion amount control is a control for adjusting the amount of toner adhesion to the photoreceptor 1. Laser diode light amount control is control that adjusts the light amount (output) of the laser diode 213. Registration control is control for adjusting the position of the medium. γ correction control is control for correcting the gradation of an image.

FIG. 14 is a diagram showing a list of types of stabilization processing. Each stabilization process includes a different sequence. Therefore, in one aspect, the control unit 50 disables the function of the port that outputs the serial clock before starting the first sequence of each stabilization process, and outputs the serial clock after the completion of the last sequence of each stabilization process. You may also enable the functionality of the port.

As described above, the image forming apparatus 100 according to the present embodiment disables the serial communication function of the control section 50 during light emission control based on various counter values set in the light emission control section 211. With this function, the image forming apparatus 100 prevents serial communication and light emission control from occurring simultaneously. As a result, a voltage drop does not occur in the light emission control unit 211, and malfunctions of the counter 316 due to the voltage drop also do not occur, and the quality of the printed image is improved.

The embodiments disclosed this time should be considered to be illustrative in all respects and not restrictive. The scope of the present disclosure is indicated by the claims rather than the above description, and it is intended that all changes are included within the meaning and scope equivalent to the claims. Furthermore, the disclosures described in the embodiments and each modification are intended to be implemented alone or in combination to the extent possible.

1 Photoreceptor, 3 Exposure section, 10 Imaging unit, 12 Intermediate transfer belt, 22 Fixing section, 30 Paper feeding section, 32 Sending roller, 34 Conveyance roller, 36 Registration roller, 50 Control section, 52 Power supply section, 60 Operation panel, Reference Signs List 100 image forming device, 110 print engine, 120 original reading section, 122 image scanner, 124 original feeding table, 126 automatic document feeding device, 128 original discharge table, 203 image processing section, 204 light emission mode control section, 210 print head part, 211 light emission control part, 212 polygon motor, 213 laser diode, 214 optical sensor, 215 dust sensor, 216 humidity sensor, 302 image signal line, 303 serial signal line, 304 SOS signal line, 801A, 801B, 1001, 1002, 1003A, 1003B signal line, 311 OR circuit 311 circuit, 312 laser diode drive section, 314 timing signal generation section, 315 counter value memory, 316 counter, 317 light amount correction section, 318 correction value memory, 319 reference clock generation section, 320 error Detection unit, 321 Polygon mirror, 403 fθ lens, 404C, 404K, 404M, 404Y, 405C, 405K, 405M, 405Y, 503C, 503K, 503M, 503Y, 504, 511 Reflection mirror, 502C, 502K, 502M, 502Y Collimator lens , 1004A, 1004B AND circuit.

Claims (20)

a photoreceptor that forms a toner image;
a light emitting element that exposes the photoreceptor;
a light emission control unit that executes light emission control of the light emitting element;
a control unit that transmits a signal for controlling the light emitting element to the light emission control unit,
The control unit and the light emission control unit are configured to be able to transmit and receive signals via a serial communication channel,
In the image forming apparatus, the control section prohibits transmitting the signal to the light emission control section in order to prevent a voltage drop in the light emission control section when the light emission control section causes the light emitting element to emit light. . The image forming apparatus according to claim 1, wherein the control section disables a communication function via the communication path based on the fact that the light emission control section causes the light emitting element to emit light. The communication path includes a communication path for a clock signal,
3. The image forming apparatus according to claim 2, wherein disabling the communication function via the communication path includes disabling the clock signal transmission function. The control unit includes:
generating a parameter regarding the timing at which light emission of the light emitting element ends;
transmitting the parameters to the light emission control unit via the communication path;
Based on the parameters, the light emission control unit determines whether the light emitting element is causing light to emit light;
The image forming apparatus according to claim 2 , wherein the light emission control section causes the light emitting element to emit light based on the parameter. The light emission control unit includes an error detection unit for detecting an error related to light emission processing,
The control unit includes:
After transmitting the parameters to the light emission control unit, the light emission control unit determines whether the light emitting element is causing the light emitting element to emit light;
The image forming apparatus according to claim 4, wherein after the light emitting element finishes emitting light, a signal for requesting the value detected by the error detection section is transmitted to the light emission control section. The light emission control section includes:
causing the light emitting element to emit light in order to obtain a horizontal synchronization signal for exposure timing of the light emitting element;
The image forming apparatus according to claim 4, wherein the light emitting element is caused to emit light in order to sample the amount of light from the light emitting element. The said parameters are:
a first counter value for light emission processing to obtain the horizontal synchronization signal;
The image forming apparatus according to claim 6, further comprising a second counter value for light emission processing for sampling the amount of light of the light emitting element. a photoreceptor that forms a toner image;
a light emitting element that exposes the photoreceptor;
a first light emission control section and a second light emission control section that execute light emission control of the light emitting element;
a control unit that transmits a signal for controlling the light emitting element to each of the first light emission control unit and the second light emission control unit,
The control unit outputs a first select signal and a second select signal for selecting a communication destination,
The first light emission control unit receives the first selection signal via a first communication path,
The second light emission control unit receives the second selection signal via a second communication path,
The first and second light emission control units are further connected to the control unit via a third communication path for data transmission and reception,
The control unit includes:
Determining whether each of the first light emission control unit and the second light emission control unit causes the light emitting element to emit light;
Based on a result of the determination, the image forming apparatus sets a select signal, which selects a light emission control unit that causes the light emitting element to emit light, of the first select signal and the second select signal to LOW. The third communication path includes a communication path for a clock signal,
The first communication path and the clock signal communication path are connected to an input port of a first logic circuit,
A communication path on the output port side of the first logic circuit is connected to the first light emission control section,
The first logic circuit outputs a HIGH signal only when signals on both the first communication path and the clock signal communication path are HIGH,
The second communication path and the clock signal communication path are connected to an input port of a second logic circuit,
A communication path on the output port side of the second logic circuit is connected to the second light emission control section,
The image forming apparatus according to claim 8, wherein the second logic circuit outputs a HIGH signal only when signals on both the second communication path and the clock signal communication path are HIGH. The control unit includes:
generating a parameter regarding the timing at which light emission of the light emitting element ends;
transmitting the parameters to each of the first and second light emission control units via the third communication path;
Each of the first and second light emission control units causes the light emitting element to emit light based on the parameter,
Determining whether each of the first light emission control section and the second light emission control section causes the light emitting element to emit light includes determining which light emission control section causes the light emitting element to emit light based on the parameters. The image forming apparatus according to claim 8 or 9, further comprising determining whether or not light is being emitted. Each of the first and second light emission control sections includes an error detection section for detecting errors related to light emission processing,
The control unit includes:
After transmitting the parameters to either the first or second light emission control unit, determining whether the light emission control unit to which the parameters are transmitted is causing the light emitting element to emit light;
2. A signal for requesting a value detected by the error detection unit is transmitted to the light emission control unit to which the parameter is to be transmitted, after a precontrol unit to which the parameter is to be transmitted has finished emitting light from the light emitting element. 11. The image forming apparatus according to 10. The first and second light emission control sections are
causing the light emitting element to emit light in order to obtain a horizontal synchronization signal for exposure timing of the light emitting element;
The image forming apparatus according to claim 10 or 11, wherein the light emitting element is caused to emit light in order to sample the amount of light from the light emitting element. The said parameters are:
a first counter value for light emission processing to obtain the horizontal synchronization signal;
The image forming apparatus according to claim 12, further comprising a second counter value for light emission processing for sampling the amount of light of the light emitting element. A method for controlling an image forming apparatus, the method comprising:
The image forming apparatus includes:
a light emission control unit that executes light emission control of the light emitting element;
a control unit that transmits a signal for controlling the light emitting element to the light emission control unit,
The control unit and the light emission control unit are configured to be able to transmit and receive signals via a serial communication channel,
A control method comprising the step of prohibiting the control unit from transmitting the signal to the light emission control unit in order to prevent a voltage drop in the light emission control unit when the light emission control unit causes a light emitting element to emit light. . 15. The control method according to claim 14 , further comprising the step of disabling a communication function via the communication path based on the fact that the light emission control section causes the light emitting element to emit light. The communication path includes a communication path for a clock signal,
16. The control method according to claim 15, wherein disabling the communication function via the communication path includes disabling the clock signal transmission function. generating a parameter regarding the timing at which light emission of the light emitting element ends;
transmitting the parameters to the light emission control unit via the communication path;
a step of determining whether the light emission control unit causes the light emitting element to emit light based on the parameter;
The control method according to claim 15 or 16, comprising the step of causing the light emitting element to emit light based on the parameter. After transmitting the parameters to the light emission control unit, determining whether the light emission control unit is causing the light emitting element to emit light;
18. The method further comprises the step of transmitting a signal to the light emission control section to request a value detected by an error detection section provided in the light emission control section after the light emission of the light emitting element is completed. control method. The said parameters are:
a first counter value for light emission processing to obtain a horizontal synchronization signal for exposure timing of the light emitting element;
The control method according to claim 17 or 18, further comprising a second counter value for light emission processing for sampling the light amount of the light emitting element. A method for controlling an image forming apparatus, the method comprising:
determining whether each of the first light emission control section and the second light emission control section causes the light emitting element to emit light;
Based on the result of the determination, a first select signal is sent to the first light emission control unit via a first communication path and a first selection signal is sent to the second light emission control unit via a second communication path. A control method comprising the step of setting a select signal, which selects a light emission control unit that causes the light emitting element to emit light, of a second select signal that causes the light emitting element to emit light, to LOW.

Images