Image-forming device
Patent Information
- Application Number
- JP2023141505
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Filing Date
- 2023-08-31
- Publication Date
- 2025-03-13
Smart Images
Figure 2025034847000001_ABST
Abstract
Description
[Technical field]
[0001] The present application relates to an image forming apparatus that includes an image forming unit that forms an image on a sheet and determines whether or not abnormal discharge has occurred in the image forming unit. [Background technology]
[0002] The image forming apparatus described in Patent Document 1 counts the number of inputs when the charging voltage is higher than a predetermined reference value. The image forming apparatus then determines whether or not an abnormal discharge such as an arc discharge has occurred based on the count value, and stops applying the charging voltage when it determines that an abnormal discharge has occurred. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] JP 2010-197969 A Summary of the Invention [Problem to be solved by the invention]
[0004] It is fine if the configuration for determining whether or not the above-mentioned abnormal discharge has occurred is realized by a hardware circuit and a custom ASIC equipped with that hardware circuit is used; however, if a similar configuration is realized by software in a general-purpose SoC (System on a Chip), there is a risk that, depending on the type of malfunction, it will not be possible to determine whether or not abnormal discharge has occurred.
[0005] The present application aims to provide technology that makes it possible to reliably determine whether or not abnormal discharge has occurred, even when the configuration for determining whether or not abnormal discharge has occurred in an image forming unit is realized by software. [Means for solving the problem]
[0006] In order to achieve the above object, the image forming apparatus of the present application comprises an image forming unit that forms an image on a sheet, a high-voltage power supply board that applies a high voltage to the image forming unit based on a supplied voltage, the high-voltage power supply board that detects an overcurrent flowing in the image forming unit and outputs a discharge detection signal, a switching circuit that switches between supplying and stopping voltage to the high-voltage power supply board, a first control unit to which the discharge detection signal is input, and a second control unit that controls the high-voltage voltage by outputting a control signal to the high-voltage power supply board, the second control unit to which the discharge detection signal is input, wherein the first control unit executes a first judgment process of determining whether or not an abnormal discharge has occurred in the image forming unit based on the input discharge detection signal, and a first instruction process of instructing the switching circuit to stop the voltage to the high-voltage power supply board when it is determined in the first judgment process that an abnormal discharge has occurred in the image forming unit, and the second control unit executes a second judgment process of determining whether or not an abnormal discharge has occurred in the image forming unit based on the input discharge detection signal, and a second instruction process of instructing the switching circuit to stop the voltage to the high-voltage power supply board when it is determined in the second judgment process that an abnormal discharge has occurred in the image forming unit.
[0007] The first control unit executes a first determination process to determine whether or not an abnormal discharge has occurred in the image forming unit based on the input discharge detection signal, and the second control unit similarly executes a second determination process to determine whether or not an abnormal discharge has occurred in the image forming unit based on the input discharge detection signal. Therefore, even if an abnormality occurs in the first control unit and the first determination process cannot be executed, the second control unit executes a second determination process similar to the first determination process, so that it is possible to determine whether or not an abnormal discharge has occurred in the image forming unit. Conversely, even if an abnormality occurs in the second control unit and the second determination process cannot be executed, the first control unit executes a first determination process similar to the second determination process, so that it is possible to determine whether or not an abnormal discharge has occurred in the image forming unit. In this way, even if an abnormality occurs in either the first control unit or the second control unit, when an abnormality does not occur in the other, it is possible to determine whether or not an abnormal discharge has occurred in the image forming unit, so that it is possible to reliably perform the determination. As a result, when it is determined that an abnormal discharge has occurred in the image forming unit, it is possible to reliably instruct the switching circuit to stop the voltage to the high-voltage power supply board by the first instruction process or the second instruction process.
[0008] The first control unit counts the number of times a discharge detection signal is input in the first judgment process, and if the counted number is equal to or greater than a predetermined number, determines that an abnormal discharge has occurred in the image forming unit and sets first information indicating that the first control unit has determined that an abnormal discharge has occurred; and the second control unit counts the number of times a discharge detection signal is input in the second judgment process, and if the counted number is equal to or greater than a predetermined number, determines that an abnormal discharge has occurred in the image forming unit and sets second information indicating that the second control unit has determined that an abnormal discharge has occurred.
[0009] As a result, in both the first judgment process performed by the first control unit and the second judgment process performed by the second control unit, when the discharge detection signal is input a predetermined number of times or more, it is judged that abnormal discharge has occurred in the image forming unit, thereby improving the accuracy of judging the occurrence of abnormal discharge.
[0010] The first control unit is also characterized in that, after executing the first instruction process, it determines whether the second information is set or not, and if the second information is not set, it instructs the second control unit to perform initialization.
[0011] When the first control unit executes the first instruction process, the second control unit should have set the second information, so if the second information has not been set at this time, it is considered that some kind of abnormality has occurred in the second control unit. Therefore, the first control unit can resolve the abnormality in the second control unit by instructing the second control unit to perform initialization.
[0012] The second control unit is also characterized in that, after executing the second instruction process, it determines whether the first information is set or not, and if the first information is not set, it instructs the first control unit to perform initialization.
[0013] When the second control unit executes the second instruction process, the first control unit should have set the first information, so if the first information has not been set at this time, it is considered that some kind of abnormality has occurred in the second control unit. Therefore, the second control unit can resolve the abnormality in the first control unit by instructing the first control unit to perform initialization.
[0014] In addition, the image forming apparatus of the present application is characterized by further comprising an instruction circuit to which an instruction by a first instruction process and an instruction by a second instruction process are input, and which instructs the switching circuit to stop the supply of voltage to the high-voltage power supply board when at least one of an instruction by the first instruction process and an instruction by the second instruction process is input.
[0015] As a result, when at least one of an instruction from the first instruction process and an instruction from the second instruction process is input, the switching circuit is instructed to stop the voltage to the high-voltage power supply board. Therefore, even if an abnormality occurs in either the first control unit or the second control unit, if no abnormality occurs in the other, the first instruction process or the second instruction process can reliably instruct the switching circuit to stop the voltage to the high-voltage power supply board.
[0016] The first control unit outputs a deep sleep signal to transition the image forming device into a deep sleep state when a predetermined condition is met, including when it is determined in the first judgment process that abnormal discharge is occurring in the image forming unit, and the deep sleep signal is input to the instruction circuit instead of an instruction from the first instruction process, and when at least one of the deep sleep signal and an instruction from the second instruction process is input, the instruction circuit instructs the switching circuit to stop the voltage to the high-voltage power supply board.
[0017] As a result, the instructions from the first instruction process are substituted with a deep sleep signal that is originally provided in the image forming device, so that the first instruction process can be omitted and the output terminal that outputs the instructions from the first instruction process can be omitted.
[0018] The image forming apparatus of the present application is characterized in that it further includes a low-voltage power supply circuit that supplies a voltage to the high-voltage power supply board, and the deep sleep signal is a signal that instructs the low-voltage power supply circuit to supply a voltage lower than the voltage.
[0019] In this way, since the deep sleep signal is a signal that is originally provided in the image forming device, by substituting the deep sleep signal for the instructions from the first instruction process, the first instruction process can be omitted and the output terminal that outputs the instructions from the first instruction process can be omitted.
[0020] The image forming unit has a photosensitive drum, a charger that charges the photosensitive drum, and an exposure unit that forms an electrostatic latent image on the photosensitive drum charged by the charger, and the abnormal discharge in the image forming unit is an abnormal discharge in the charger.
[0021] This makes it possible to reliably determine whether abnormal discharge has occurred in the charger.
[0022] The first control unit, after executing the first instruction process, attempts to communicate with the second control unit, and if communication is not possible, instructs the second control unit to perform initialization.
[0023] In this way, if the first control unit is operating normally and the first control unit cannot communicate with the second control unit, it is considered that some abnormality has occurred in the second control unit. Therefore, the first control unit can resolve the abnormality in the second control unit by instructing the second control unit to perform initialization.
[0024] Moreover, the second control unit attempts to communicate with the first control unit after executing the second instruction process, and if communication is not possible, instructs the first control unit to perform initialization.
[0025] In this way, if the second control unit is operating normally and cannot communicate with the first control unit, it is considered that some abnormality has occurred in the first control unit. Therefore, the second control unit can resolve the abnormality in the first control unit by instructing the first control unit to perform initialization. [Brief description of the drawings]
[0026] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a color laser printer according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a block diagram showing a control configuration of the color laser printer of FIG. [Diagram 3] 3 is a block diagram showing transmission paths of some signals around the main board in FIG. 2. [Figure 4] 3 is a flowchart showing a procedure of a control process executed by a main control circuit mounted on the main board of FIG. 2. [Diagram 5] 3 is a flowchart showing the procedure of a control process executed by a sub-control circuit mounted on the main board of FIG. 2. [Figure 6] FIG. 11 is a block diagram showing some signal transmission paths around a main board of a color laser printer according to a second embodiment of the present application. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0027] Hereinafter, embodiments of the present application will be described in detail with reference to the drawings.
[0028] (First embodiment) FIG. 1 shows a cross-sectional view of the schematic configuration of a color laser printer (hereinafter, simply referred to as printer) 1 according to a first embodiment of the present application. Printer 1 is a so-called tandem type laser printer that uses four color toners. In the following explanation, as shown in FIG. 1, the explanation will be based on the direction as seen by a user using printer 1. That is, the right side in FIG. 1 will be referred to as the "front", the left side as the "rear", the upper side as the "upper", the lower side as the "lower", the near side as the "left" and the far side as the "right".
[0029] As shown in FIG. 1, the printer 1 includes a main body housing 2, a supply unit 10, and an image forming unit 20. The main body housing 2 is substantially box-shaped. The main body housing 2 houses the supply unit 10, the image forming unit 20, and the like. An output tray 5 is formed on the top surface of the main body housing 2. The printer 1 outputs the sheets S on which images have been formed in a stacked state onto the output tray 5. A front cover 2a is provided on the front surface of the main body housing 2. The front cover 2a is a cover that opens and closes an opening 2b formed on the front surface of the main body housing 2. The front cover 2a can be rotated forward around a rotation shaft 2c provided at the lower end, for example, and can be rotated from a position where the opening 2b shown in FIG. 1 is closed to a position where the opening 2b is opened (opened).
[0030] The supply unit 10 includes a supply tray 11 in which the sheets S are stored, a pickup roller 12, a separation pad 13, a pressure plate 14, and various rollers including a registration roller 15. The sheets S are, for example, standard sheets such as A4 size, but are not limited to paper media such as plain paper or thick paper, and may be other recording media such as OHP film. The supply tray 11 is detachably attached to the lower part of the main body housing 2. The pressure plate 14 is provided in the supply tray 11. A displacement mechanism (not shown) is provided below the pressure plate 14. Prior to image formation, the displacement mechanism displaces the pressure plate 14 to an inclined state so that the front side is higher. As a result, the sheets S stored in the supply tray 11 are brought toward the pickup roller 12 by the pressure plate 14, separated one by one by the pickup roller 12 and the separation pad 13, and the front ends of the sheets S are aligned by the registration roller 15, and then conveyed to the image forming unit 20 by other rollers. The sheet S conveyed out of the supply tray 11 is conveyed along a conveying path R by the image forming unit 20, a discharge roller 65, etc., and is discharged onto a discharge tray 5.
[0031] The image forming unit 20 is provided in the approximate center of the inside of the main body housing 2, and includes the developing cartridges 30Y, 30M, 30C, and 30K, an exposure unit 40, a transfer unit 50, and a fixing unit 60. The developing cartridges 30Y, 30M, 30C, and 30K accommodate yellow, magenta, cyan, and black toners, respectively. The four developing cartridges 30Y to 30K are provided in this order from the front to the rear of the printer 1. The developing cartridges 30Y to 30K can be removed and replaced by opening the front cover 2a and removing them through the opening 2b of the main body housing 2.
[0032] The developing cartridge 30K includes a photosensitive drum 31, a charger 32, and a toner cartridge 33K. The other developing cartridges 30C, 30M, and 30Y have different toner colors, but are otherwise similar in configuration to the developing cartridge 30K. For this reason, the following description will mainly focus on the developing cartridge 30K, and descriptions of the other developing cartridges 30C, 30M, and 30Y will be omitted as appropriate.
[0033] The charger 32 is, for example, a scorotron type charger including a charging wire 32a and a grid portion 32b. The charger 32 uniformly charges the surface of the photoconductor drum 31 to a positive charge before forming an electrostatic latent image on the surface of the photoconductor drum 31 in image formation. The device for charging the photoconductor drum 31 is not limited to a scorotron type charger, but may be another device such as a roller-type charging roller. The polarity for charging the photoconductor drum 31 is not limited to a positive charge, but may be a negative charge.
[0034] The toner cartridge 33K includes a toner storage chamber 33a, an agitator 33e, a supply roller 33b, a developing roller 33f, and a layer thickness regulating blade 33d. The toner storage chamber 33a stores black toner. The agitator 33e agitates the toner stored in the toner storage chamber 33a. The supply roller 33b is provided in the toner storage chamber 33a and rotates by a driving force transmitted from a process motor 111 (see FIG. 2) provided in the main body housing 2. The supply roller 33b supplies the toner supplied from the toner storage chamber 33a to the developing roller 33f. The photosensitive drum 31 rotates, for example, in a clockwise direction in FIG. 1. The developing roller 33f is provided diagonally behind and below the supply roller 33b and is in contact with the supply roller 33b. The developing roller 33f is also disposed downstream of the charger 32 in the rotation direction of the photosensitive drum 31. The developing roller 33f also rotates by receiving a driving force from the process motor 111. A positive voltage is applied to the roller shaft of the developing roller 33f. The toner supplied to the developing roller 33f is carried on the developing roller 33f as the developing roller 33f rotates. The layer thickness regulating blade 33d is provided so as to be in pressure contact with the developing roller 33f from above, and regulates the thickness of the toner adhering to the outer peripheral surface of the developing roller 33f to a constant value. The toner cartridges 33C, 33M, and 33Y of the other colors (cyan, magenta, and yellow) shown in FIG. 1 have the same configuration as the toner cartridge 33K.
[0035] The exposure unit 40 is provided at the top inside the main body housing 2, and includes a laser light source, a polygon mirror, a lens, a reflecting mirror, etc. (not shown). A laser beam emitted from the laser light source is deflected by a polygon mirror, etc., and is emitted from the exposure unit 40. The exposure unit 40 exposes the surface of the photoconductor drum 31 by emitting a light beam shown by a dashed line in FIG. 1 to the surface of the photoconductor drum 31. As a result, an electrostatic latent image is formed on the surface of the photoconductor drum 31. The toner carried on the development roller 33f moves to the electrostatic latent image on the photoconductor drum 31 due to the potential difference between the development roller 33f and the electrostatic latent image formed on the photoconductor drum 31, and forms a toner image.
[0036] The transfer unit 50 is disposed at a position above the supply unit 10 and below the development cartridge 30C. The transfer unit 50 transports the sheet S supplied by the supply unit 10 toward the discharge tray 5. The transfer unit 50 includes a drive roller 51, a driven roller 52, a conveyor belt 53, and a plurality of (four in this embodiment) transfer rollers 54. The conveyor belt 53 is, for example, an endless belt formed by shaping a belt in a loop, and is stretched between the drive roller 51 located below the rear end side of the development cartridge 30C and the driven roller 52 located below the front end side of the development cartridge 30K.
[0037] Each of the multiple transfer rollers 54 is disposed at a position facing each photosensitive drum 31 in the up-down direction, with a sheet transport surface 53A, which is the outer circumferential surface of the transport belt 53, sandwiched therebetween, and is in contact with the transport belt 53 from the rear side of the sheet transport surface 53A. A negative transfer voltage is applied to each of the multiple transfer rollers 54 in accordance with the transport timing of the sheet S, thereby transferring the toner image carried on the surface of the photosensitive drum 31 to the sheet S transported along the sheet transport surface 53A.
[0038] The fixing unit 60 is provided downstream in the transport direction from the position of the transfer unit 50. The fixing unit 60 includes a heating roller 61 that heats the sheet S, a pressure roller 62 that sandwiches the sheet S between the heating roller 61, and a thermistor 63 (see FIG. 2). The image forming unit 20 transports the sheet S with the toner image transferred thereto to the fixing unit 60. The fixing unit 60 thermally fixes the toner image transferred to the sheet S to the sheet S by transporting the sheet S between the heating roller 61 and the pressure roller 62. The sheet S with the printed image is discharged to the discharge tray 5 by discharge rollers 65.
[0039] Thermistor 63 is provided near heating roller 61 and detects the temperature of heating roller 61. Thermistor 63 outputs a signal corresponding to the detected temperature to main control circuit 101 (see FIG. 2).
[0040] Although the fixing unit 60 has a configuration including the heating roller 61 and the pressure roller 62, the present invention is not limited to this. For example, the fixing unit may have a heater, a nip plate that receives radiant heat from the heater, a heating belt that rotates around the nip plate, and a pressure roller.
[0041] The fixing unit may have a substrate on which a heat generating pattern is formed, a belt that rotates around the substrate, and a pressure roller, and the substrate and the belt are in contact with each other. The fixing unit may have a heating roller, a heater, and a pressure belt.
[0042] Next, the control configuration of the printer 1 will be described with reference to Fig. 2. As shown in Fig. 2, the printer 1 further includes a main control circuit 101, a ROM 102, a RAM 103, a non-volatile memory 104, and a sub-control circuit 105. The main control circuit 101, the ROM 102, the RAM 103, the non-volatile memory 104, the sub-control circuit 105, a DC-DC converter 106, a main motor driver MD1, and a process motor driver MD2 are mounted on the main board 100.
[0043] The main control circuit 101 is, for example, a general-purpose SoC equipped with a CPU (not shown), and performs overall control of each part of the printer 1. The main control circuit 101 is electrically connected to the ROM 102, the RAM 103, the non-volatile memory 104, the sub-control circuit 105, the DC-DC converter 106, the main motor driver MD1, and the process motor driver MD2. The main control circuit 101 is also connected to the sub-control circuit 105 via a signal line L1. The signal line L1 is a signal line for transmitting data between the main control circuit 101 and the sub-control circuit 105. As a communication method, for example, UART (Universal Asynchronous Receiver Transmitter) is used, but is not limited to this method. A specific example of data transmitted through the signal line L1 will be described later in the control process of FIG. 4 and FIG. 5.
[0044] The ROM 102 stores various control programs and various settings for controlling the printer 1. The program for the control process in FIG. 4 is included in the various control programs.
[0045] The RAM 103 is used as a working area from which various control programs are read, and as a storage area for temporarily storing image data included in a job. The main control circuit 101 (its CPU) controls each part of the printer 1 while storing the processing results in the RAM 103 or non-volatile memory 104 in accordance with the control programs read from the ROM 102 and signals output from various sensors including the thermistor 63.
[0046] The main motor driver MD1 controls the drive voltage based on a control signal from the main control circuit 101, and outputs the drive voltage to the main motor 110 to control the drive of the main motor 110. The main motor 110 drives the heating roller 61 and pressure roller 62 of the fixing unit 60, and the roller group 120. The roller group 120 includes the pickup roller 12, the registration roller 15, and the discharge roller 65. The drive force of the main motor 110 is transmitted to the heating roller 61 and the roller group 120 via a gear group (not shown). That is, in order to show that the drive force of the main motor 110 is indirectly transmitted to the heating roller 61 and the roller group 120 via the gear group, the main motor 110 is connected to the heating roller 61 and the roller group 120 by dashed lines in FIG. 2.
[0047] A control signal is also supplied to the process motor driver MD2 from the main control circuit 101. The process motor driver MD2 controls a drive voltage based on the control signal from the main control circuit 101, and outputs the drive voltage to the process motor 111 to control the drive of the process motor 111. The process motor 111 drives four developing rollers 33f and four photosensitive drums 31. The reason why the process motor 111 is connected to the developing rollers 33f and photosensitive drums 31 by dashed lines is the same as the reason why the main motor 110 is connected to the heating roller 61 and roller group 120 by dashed lines.
[0048] A low-voltage power supply board 113 is connected to the DC-DC converter 106. The low-voltage power supply board 113 includes an AC-DC converter (not shown) and converts an input AC voltage (e.g., commercial AC 100V) to a DC voltage (e.g., DC 24V) by the AC-DC converter and outputs it to the DC-DC converter 106 and the high-voltage power supply board 112 (see FIG. 3). The DC-DC converter 106 converts the input DC 24V to a lower DC voltage (e.g., DC 3.3V) and supplies it to the main control circuit 101 and the sub-control circuit 105 as a power supply voltage.
[0049] The sub-control circuit 105 is configured, for example, by an MCU (Micro Controller Unit), and outputs a high-voltage control signal for controlling the high-voltage power supply board 112 to the high-voltage power supply board 112. The high-voltage power supply board 112 applies a high-voltage charging voltage (for example, about 1 kV) to the four chargers 32 based on DC 24 V supplied from the low-voltage power supply board 113. The value of this charging voltage is controlled based on the high-voltage control signal from the sub-control circuit 105.
[0050] FIG. 3 shows some signal transmission paths around the main board 100. As shown in FIG. 3, the high-voltage power supply board 112 has an output terminal OUT31, and outputs a discharge detection signal from the output terminal OUT31 when an abnormal discharge such as over-discharge occurs in any of the four chargers 32. The discharge detection signal indicates that an abnormal discharge has occurred when it is H, and indicates that an abnormal discharge has not occurred when it is L, but this logic may be reversed. The output terminal OUT31 is connected to the input terminal IN2 of the sub-control circuit 105 via a signal line L5, and is connected to the input terminal IN1 of the main control circuit 101 via a signal line L6 branched from the signal line L5. Therefore, the main control circuit 101 can detect that an abnormal discharge has occurred in any of the chargers 32 based on the discharge detection signal input to the input terminal IN1. Similarly, the sub-control circuit 105 can also detect that an abnormal discharge has occurred in any of the chargers 32 based on the discharge detection signal input to the input terminal IN2.
[0051] Furthermore, the input terminal IN41 of the high-voltage power supply board 112 is connected to the output terminal OUT4 of the sub-control circuit 105 via a signal line L7. The high-voltage control signal is transmitted from the sub-control circuit 105 to the high-voltage power supply board 112 via the signal line L7.
[0052] The main control circuit 101 has an output terminal OUT1, and outputs a D-SLEEP signal from the output terminal OUT1 when a predetermined condition is satisfied and the printer 1 is to be put into a deep sleep state. The D-SLEEP signal indicates that the printer 1 is to be put into a deep sleep state when it is L, and indicates that the printer 1 is not to be put into a deep sleep state when it is H, but this logic may be reversed. The output terminal OUT1 is connected to the input terminal IN11 of the low-voltage power supply board 113 via a signal line L2. Therefore, the low-voltage power supply board 113 can detect whether or not the printer 1 is to be put into a deep sleep state based on the D-SLEEP signal input to the input terminal IN11. The low-voltage power supply board 113 outputs DC24V from the output terminal OUT11 when the D-SLEEP signal is H, that is, when the printer 1 is not to be put into a deep sleep state, while it outputs a DC voltage lower than DC24V, for example DC6V, from the output terminal OUT11 when the D-SLEEP signal is L, that is, when the printer 1 is to be put into a deep sleep state.
[0053] The output terminal OUT11 is connected to an input terminal IN21 of a relay 108 via a power line PL1. The output terminal OUT21 of the relay 108 is connected to an input terminal IN31 of a high-voltage power supply board 112 via a power line PL2. The on / off of the relay 108 is controlled by the output of an AND circuit 107.
[0054] An output terminal OUT2 of the main control circuit 101 is connected to the input side of the AND circuit 107 via a signal line L3, and an output terminal OUT3 of the sub-control circuit 105 is connected to the input side of the AND circuit 107 via a signal line L4. The main control circuit 101 outputs an HV_ENABLE1 signal from an output terminal OUT2, which instructs the high-voltage power supply board 112 to output / stop a high voltage. Similarly, the sub-control circuit 105 outputs an HV_ENABLE2 signal from an output terminal OUT3, which instructs the high-voltage power supply board 112 to output / stop a high voltage. Both the HV_ENABLE1 signal and the HV_ENABLE2 signal indicate that the high-voltage power supply board 112 is to output a high voltage when H, and indicate that the high-voltage power supply board 112 is to stop the high voltage when L. Therefore, the output of the AND circuit 107 is H when both the HV_ENABLE1 signal and the HV_ENABLE2 signal are H, and is L when at least one of the HV_ENABLE1 signal and the HV_ENABLE2 signal is L. If we assume that relay 108 is on when the output of AND circuit 107 is H and off when the output of AND circuit 107 is L, then when either main control circuit 101 or sub-control circuit 105 instructs high voltage power supply board 112 to output a high voltage, relay 108 is turned on and a high voltage is output from high voltage power supply board 112, and when at least one of main control circuit 101 and sub-control circuit 105 instructs high voltage power supply board 112 to stop the high voltage, relay 108 is turned off and the high voltage from high voltage power supply board 112 is stopped.
[0055] The control process executed by the printer 1 configured as above will be described in detail with reference to FIGS.
[0056] 4 shows the procedure of the control process executed by the main control circuit 101. As described above, the program for this control process is stored in ROM 102, and when executed by the main control circuit 101, it is read from ROM 102 to RAM 103. This control process is started when the sub-control circuit 105 starts applying high voltage to the high-voltage power supply board 112, for example, when the main control circuit 101 receives a print job or a print command. Hereinafter, in the explanation of each process, steps will be represented as "S".
[0057] 4, first, the main control circuit 101 (its CPU) initializes a discharge count counter to "0" (S10). The discharge count counter is, for example, a software counter configured using a register (not shown) provided in the main control circuit 101, and serves to measure the time during which the discharge detection signal input to the input terminal IN1 of the main control circuit 101 is H, that is, the time during which abnormal discharge occurs in any of the four chargers 32.
[0058] Next, the main control circuit 101 monitors at predetermined time intervals (e.g., 5 msec) whether the discharge detection signal input to the input terminal IN1 is H or L (S12). This monitoring may be performed, for example, by using an interrupt process in response to an interrupt signal set to be generated at predetermined time intervals.
[0059] Then, the main control circuit 101 judges whether the discharge detection signal monitored at every predetermined time is H or not (S14). In this judgment, if the discharge detection signal is H (S14: YES), the main control circuit 101 increments the discharge number counter by "1" (S16), and judges whether the value of the discharge number counter after the increment is equal to or less than a predetermined threshold value (e.g., 100 times) or not (S18). In this judgment, if the value of the discharge number counter is equal to or less than the predetermined threshold value (S18: YES), the main control circuit 101 judges whether the sub-control circuit 105 ends the high voltage application or not (S20). This judgment may be made, for example, based on whether the printing process corresponding to the received print job or print command is to be ended.
[0060] If the sub-control circuit 105 determines in step S20 that it will continue to apply high voltage (S20: NO), the main control circuit 101 returns the process to step S12. On the other hand, if the sub-control circuit 105 determines that it will end the application of high voltage (S20: YES), the main control circuit 101 ends the control process.
[0061] On the other hand, if it is determined in S14 that the discharge detection signal is L (S14: NO), the main control circuit 101 decrements the discharge number counter by "1" (S22) and determines whether the value of the discharge number counter after decrement is smaller than "0", that is, whether it is a negative value (S24). If it is determined that the value of the discharge number counter is a negative value (S24: YES), the main control circuit 101 initializes the discharge number counter to "0" (S26) and then proceeds to the process of S20. On the other hand, if the value of the discharge number counter is not a negative value (S24: NO), the main control circuit 101 skips S26 and proceeds to the process of S20.
[0062] On the other hand, when it is determined in S18 that the value of the discharge count counter exceeds the predetermined threshold value (S18: NO), the main control circuit 101 sets a discharge flag in the register (S30). The discharge flag is a flag that is set when the main control circuit 101 determines that an abnormal discharge has occurred in any of the four chargers 32. It goes without saying that the register (the area of the register) in which the discharge flag is set is different from the register (the area of the register) used as the discharge count counter.
[0063] Next, the main control circuit 101 sets the HV_ENABLE1 signal to L (S32) and sets the D-SLEEP signal to L (S34). This causes the HV_ENABLE1 signal of L to be output from the output terminal OUT2 and the D-SLEEP signal of L to be output from the output terminal OUT1. The low-voltage power supply board 113, which has received the D-SLEEP signal of L from the input terminal IN11, outputs DC6V in the deep sleep state from the output terminal OUT11 instead of the normal DC24V, as described above.
[0064] Furthermore, the main control circuit 101 attempts to communicate with the sub-control circuit 105 (S36). As described above, UART is adopted as the communication method in this embodiment, and the communication here is performed based on the UART communication protocol. Then, the main control circuit 101 judges whether communication is possible (S38). If communication is possible (S38: YES), the main control circuit 101 judges whether the discharge flag in the register of the sub-control circuit 105 is set (S40). Specifically, the main control circuit 101 inquires of the sub-control circuit 105 via communication whether the discharge flag is set in the register of the sub-control circuit 105, and judges whether the discharge flag in the register of the sub-control circuit 105 is set based on the response from the sub-control circuit 105. If it is determined in S40 that the discharge flag in the register of the sub-control circuit 105 is set (S40: YES), the main control circuit 101 displays an error message on the display unit (not shown) of the printer 1 indicating that an abnormal discharge has occurred in one of the four chargers 32 (S42), and then terminates the control process.
[0065] On the other hand, if the determination in S38 indicates that communication is impossible (S38: NO), the main control circuit 101 instructs the sub-control circuit 105 to reset (S44) and then ends the control process. If the determination in S40 indicates that the discharge flag of the register of the sub-control circuit 105 is not set (S40: NO), the main control circuit 101 advances the process to S44. Both the sub-control circuit 105 and the main control circuit 101 are configured to be able to input a reset instruction from the outside, and are reset when a reset instruction is input. Therefore, when the main control circuit 101 instructs the sub-control circuit 105 to reset in S44, the sub-control circuit 105 is reset to its initial state. If the determination in S38 indicates that communication with the sub-control circuit 105 is impossible, the main control circuit 101 determines that some abnormality has occurred in the sub-control circuit 105 and instructs the sub-control circuit 105 to reset. Similarly, when it is determined in S40 that the discharge flag in the register of the sub-control circuit 105 is not set, the main control circuit 101 also determines that some abnormality has occurred in the sub-control circuit 105 and instructs the sub-control circuit 105 to reset. As will be described later with reference to FIG. 5, the same processing as that in S12 to S30 is also performed for the sub-control circuit 105 in S52 to S70, so that when abnormal discharge occurs in any of the four chargers 32, a discharge flag should also be set in the register of the sub-control circuit 105. When it is determined in S40 that the discharge flag in the register of the sub-control circuit 105 is not set, the discharge flag should also be set in the register of the sub-control circuit 105, but the discharge flag is not set in the register of the sub-control circuit 105, so that the main control circuit 101 determines that some abnormality has occurred in the sub-control circuit 105 and instructs the sub-control circuit 105 to reset.
[0066] Fig. 5 shows the procedure of the control process executed by the sub-control circuit 105. The program of this control process is, for example, built into the sub-control circuit 105 and is executed only by the sub-control circuit 105. This control process is started when the sub-control circuit 105 starts applying high voltage to the high-voltage power supply board 112, similar to the control process of Fig. 4.
[0067] In Fig. 5, the processes of S50 to S70 are the same as the processes of S10 to S30 in Fig. 4, except for the process of S51. However, in Fig. 5, the discharge number counter is configured using a register of the sub-control circuit 105, and the discharge flag is set in the register of the sub-control circuit 105. Also, the discharge detection signal indicates the discharge detection signal input from the input terminal IN2 of the sub-control circuit 105. Furthermore, in S51, the sub-control circuit 105 starts high voltage control that is not included in the control process of Fig. 4, because, as described above, the sub-control circuit 105 is responsible for controlling the high voltage power supply board 112.
[0068] In S72 following S70, the sub-control circuit 105 sets the HV_ENABLE2 signal to L. This causes the HV_ENABLE2 signal of L to be output from the output terminal OUT3. Then, the sub-control circuit 105 judges whether or not communication with the main control circuit 101 has occurred within a predetermined time after stopping the high voltage control (S90) (S92). In S92, as a result of the main control circuit 101 attempting to communicate with the sub-control circuit 105 in S36 of FIG. 4, it may be judged that communication has occurred when communication is possible, and that no communication has occurred when communication is impossible. In the judgment of S92, if communication with the main control circuit 101 has occurred (S92: YES), the sub-control circuit 105 ends the control process. On the other hand, in the judgment of S92, if communication with the main control circuit 101 has not occurred (S92: NO), the sub-control circuit 105 advances the process to the next step S76.
[0069] The processes of S76 to S84 are almost the same as the processes of S36 to S44 in Fig. 4, except that there is no process of displaying an error in S42. However, the difference is that the processes of S36 to S44 are directed to the sub-control circuit 105, whereas the processes of S76 to S84 are directed to the main control circuit 101. As such, the processes of S36 to S44 and S76 to S84 are almost the same, and therefore further explanation of the processes of S76 to S84 will be omitted.
[0070] As described above, the printer 1 of this embodiment includes an image forming unit 20 that forms an image on a sheet S, a high-voltage power supply board 112 that applies a high-voltage voltage to the image forming unit 20 based on a supplied DC 24V voltage, the high-voltage power supply board 112 detecting an overcurrent flowing in the image forming unit 20 and outputting a discharge detection signal, a relay 108 that switches between supplying and stopping the DC 24V voltage to the high-voltage power supply board 112, a main control circuit 101 to which the discharge detection signal is input, and a sub-control circuit 105 that controls the high-voltage voltage by outputting a control signal to the high-voltage power supply board 112, the sub-control circuit 105 to which the discharge detection signal is input.
[0071] The main control circuit 101 executes a first judgment process (S18) for judging whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and a first instruction process (S32) for instructing the relay 108 to stop the supply of DC 24V voltage to the high-voltage power supply board 112 when it is judged in the first judgment process that an abnormal discharge has occurred in the image forming unit 20 (S18: NO).The sub-control circuit 105 executes a second judgment process (S58) for judging whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and a second instruction process (S72) for instructing the relay 108 to stop the supply of DC 24V voltage to the high-voltage power supply board 112 when it is judged in the second judgment process that an abnormal discharge has occurred in the image forming unit 20 (S58: NO).
[0072] In the printer 1 of this embodiment, the main control circuit 101 executes a first judgment process to judge whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and the sub-control circuit 105 similarly executes a second judgment process to judge whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal. Therefore, even if an abnormality occurs in the main control circuit 101 and the first judgment process cannot be executed, the sub-control circuit 105 executes a second judgment process similar to the first judgment process, so that it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20. Conversely, even if an abnormality occurs in the sub-control circuit 105 and the second judgment process cannot be executed, the main control circuit 101 executes a first judgment process similar to the second judgment process, so that it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20. In this way, even if an abnormality occurs in either the main control circuit 101 or the sub-control circuit 105, it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20 when no abnormality occurs in the other, so that it is possible to reliably perform the judgment. As a result, when it is determined that abnormal discharge is occurring in the image forming unit 20, it is possible to reliably instruct the relay 108 to stop the voltage to the high-voltage power supply board 112 by the first instruction process or the second instruction process.
[0073] In addition, the main control circuit 101 counts the number of times a discharge detection signal is input in a first judgment process, and if the counted number is equal to or greater than a predetermined number, determines that an abnormal discharge has occurred in the image forming unit 20 and sets first information (discharge flag) indicating that the main control circuit 101 has determined that an abnormal discharge has occurred, and the sub-control circuit 105 counts the number of times a discharge detection signal is input in a second judgment process, and if the counted number is equal to or greater than a predetermined number, determines that an abnormal discharge has occurred in the image forming unit 20 and sets second information (discharge flag) indicating that the sub-control circuit 105 has determined that an abnormal discharge has occurred.
[0074] As a result, in both the first judgment process performed by the main control circuit 101 and the second judgment process performed by the sub-control circuit 105, when a discharge detection signal is input a predetermined number of times or more, it is judged that an abnormal discharge has occurred in the image forming unit 20, thereby improving the accuracy of judging the occurrence of an abnormal discharge.
[0075] Furthermore, the main control circuit 101 is characterized in that, after executing the first instruction process, it determines whether or not the second information is set, and if the second information is not set, it instructs the sub-control circuit 105 to perform initialization.
[0076] When the main control circuit 101 executes the first instruction process, the sub-control circuit 105 should have set the second information, so if the second information has not been set at this time, it is considered that some kind of abnormality has occurred in the sub-control circuit 105. For this reason, the main control circuit 101 can resolve the abnormality in the sub-control circuit 105 by instructing the sub-control circuit 105 to perform initialization.
[0077] Furthermore, the sub-control circuit 105 is characterized in that, after executing the second instruction process, it determines whether or not the first information is set, and if the first information is not set, it instructs the main control circuit 101 to perform initialization.
[0078] When the sub-control circuit 105 executes the second instruction process, the main control circuit 101 should have set the first information, so if the first information has not been set at this time, it is considered that some kind of abnormality has occurred in the sub-control circuit 105. For this reason, the sub-control circuit 105 can resolve the abnormality in the main control circuit 101 by instructing the main control circuit 101 to perform initialization.
[0079] The printer 1 is further characterized by including an AND circuit 107 to which an instruction from a first instruction process and an instruction from a second instruction process are input, and which instructs the relay 108 to stop the supply of DC 24V voltage to the high-voltage power supply board 112 when at least one of the instructions from the first instruction process and the instructions from the second instruction process is input.
[0080] As a result, when at least one of an instruction by the first instruction process and an instruction by the second instruction process is input, the relay 108 is instructed to stop the DC 24V voltage to the high-voltage power supply board 112. Therefore, even if an abnormality occurs in either the main control circuit 101 or the sub-control circuit 105, if no abnormality occurs in the other, it is possible to reliably instruct the relay 108 to stop the voltage to the high-voltage power supply board 112 by the first instruction process or the second instruction process.
[0081] In addition, the image forming unit 20 has a photosensitive drum 31, a charger 32 that charges the photosensitive drum 31, and an exposure unit 40 that forms an electrostatic latent image on the photosensitive drum 31 charged by the charger 32, and is characterized in that the abnormal discharge in the image forming unit 20 is an abnormal discharge in the charger 32.
[0082] This makes it possible to reliably determine whether abnormal discharge has occurred in the charger 32.
[0083] Furthermore, the main control circuit 101, after executing the first instruction process, attempts to communicate with the sub-control circuit 105, and if communication is not possible, instructs the sub-control circuit 105 to perform initialization.
[0084] In this way, when the main control circuit 101 is operating normally, if the main control circuit 101 cannot communicate with the sub-control circuit 105, it is considered that some abnormality has occurred in the sub-control circuit 105. For this reason, the main control circuit 101 can resolve the abnormality in the sub-control circuit 105 by instructing the sub-control circuit 105 to perform initialization.
[0085] Furthermore, the sub-control circuit 105, after executing the second instruction process, attempts to communicate with the main control circuit 101, and if communication is not possible, instructs the main control circuit 101 to perform initialization.
[0086] In this way, when the sub-control circuit 105 is operating normally and is unable to communicate with the main control circuit 101, it is believed that some abnormality has occurred in the main control circuit 101. For this reason, the sub-control circuit 105 can resolve the abnormality in the main control circuit 101 by instructing the main control circuit 101 to perform initialization.
[0087] Second embodiment Next, a second embodiment of the present application will be described. This embodiment differs from the first embodiment only in the wiring of the main board 100', so the different parts will be mainly described and the description of the other parts will be omitted as appropriate. In addition, the hardware of this embodiment uses the hardware shown in Figures 1 and 2, including the reference numerals, as it is, and the control process of this embodiment uses the control process shown in Figures 4 and 5 almost as it is.
[0088] FIG. 6 shows the transmission paths of some signal lines around the main board 100' of this embodiment, and corresponds to FIG. 3 of the first embodiment. As can be seen by comparing FIG. 6 with FIG. 3, in FIG. 6, the output terminal OUT2 is omitted, and the output terminal OUT1 and the input side of the AND circuit 107 are directly connected via the signal line L2'. Also, the output terminal OUT1 and the input terminal IN11 of the low-voltage power supply board 113 are connected via the signal line L2, as in the first embodiment. That is, in this embodiment, the D-SLEEP signal is made to perform both the function of shifting to a deep sleep state and the function of the HV_ENABLE1 signal. The reason why the D-SLEEP signal can be used as the HV_ENABLE1 signal in this way is because the HV_ENABLE1 signal and the D-SLEEP signal are set to L in S32 and S34 of FIG. 4. However, in this embodiment, the main control circuit 101 does not output the HV_ENABLE1 signal, so the process of S32 is omitted.
[0089] As described above, the printer 1 of this embodiment includes an image forming unit that forms an image on a sheet, a high-voltage power supply board that applies a high voltage to the image forming unit 20 based on a supplied voltage and detects that an overcurrent has flowed through the image forming unit 20 and outputs a discharge detection signal, a switching circuit that switches between supplying and stopping the supply of DC 24V voltage to the high-voltage power supply board 112, a first control unit to which the discharge detection signal is input, and a second control unit that controls the high-voltage voltage by outputting a control signal to the high-voltage power supply board 112 and to which the discharge detection signal is input.
[0090] The main control circuit 101 executes a first judgment process of judging whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and a first instruction process of instructing the relay 108 to stop the DC 24V voltage to the high-voltage power supply board 112 when it is judged in the first judgment process that an abnormal discharge has occurred in the image forming unit 20. The sub-control circuit 105 executes a second judgment process of judging whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and a second instruction process of instructing the relay 108 to stop the DC 24V voltage to the high-voltage power supply board 112 when it is judged in the second judgment process that an abnormal discharge has occurred in the image forming unit 20.
[0091] In the printer 1 of this embodiment, the main control circuit 101 executes a first judgment process to judge whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal, and the sub-control circuit 105 similarly executes a second judgment process to judge whether or not an abnormal discharge has occurred in the image forming unit 20 based on the input discharge detection signal. Therefore, even if an abnormality occurs in the main control circuit 101 and the first judgment process cannot be executed, the sub-control circuit 105 executes a second judgment process similar to the first judgment process, so that it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20. Conversely, even if an abnormality occurs in the sub-control circuit 105 and the second judgment process cannot be executed, the main control circuit 101 executes a first judgment process similar to the second judgment process, so that it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20. In this way, even if an abnormality occurs in either the main control circuit 101 or the sub-control circuit 105, it is possible to judge whether or not an abnormal discharge has occurred in the image forming unit 20 when no abnormality occurs in the other, so that it is possible to reliably perform the judgment. As a result, when it is determined that abnormal discharge is occurring in the image forming unit 20, it is possible to reliably instruct the relay 108 to stop the voltage to the high-voltage power supply board 112 by the first instruction process or the second instruction process.
[0092] The printer 1 is further characterized by including an AND circuit 107 to which an instruction from a first instruction process and an instruction from a second instruction process are input, and which instructs the relay 108 to stop the supply of DC 24V voltage to the high-voltage power supply board 112 when at least one of the instructions from the first instruction process and the instructions from the second instruction process is input.
[0093] As a result, when at least one of an instruction by the first instruction process and an instruction by the second instruction process is input, the relay 108 is instructed to stop the DC 24V voltage to the high-voltage power supply board 112. Therefore, even if an abnormality occurs in either the main control circuit 101 or the sub-control circuit 105, if no abnormality occurs in the other, it is possible to reliably instruct the relay 108 to stop the voltage to the high-voltage power supply board 112 by the first instruction process or the second instruction process.
[0094] Furthermore, when a predetermined condition is met, including when it is determined in the first judgment process that an abnormal discharge has occurred in the image forming unit 20, the main control circuit 101 outputs a D-SLEEP signal for transitioning the printer 1 into a deep sleep state, and the D-SLEEP signal is input to the AND circuit 107 in place of an instruction from the first instruction process, and when at least one of the D-SLEEP signal and an instruction from the second instruction process is input, the AND circuit 107 instructs the relay 108 to stop the supply of DC 24V voltage to the high-voltage power supply board 112.
[0095] As a result, the instructions from the first instruction process are substituted with the D-SLEEP signal that is originally provided to the printer 1, so that the first instruction process can be omitted and the output terminal that outputs the instructions from the first instruction process can be omitted.
[0096] The printer 1 further includes a low-voltage power supply board 113 that supplies DC 24V to the high-voltage power supply board 112, and the D-SLEEP signal is a signal that instructs the low-voltage power supply board 113 to supply DC 6V, which is lower than the DC 24V.
[0097] In this way, since the D-SLEEP signal is a signal that is originally provided to the printer 1, by substituting the D-SLEEP signal for the instructions from the first instruction process, the first instruction process can be omitted and the output terminal that outputs the instructions from the first instruction process can be omitted.
[0098] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.
[0099] (1) In the above embodiments, a color laser printer has been described as an example of an image forming apparatus, but the image forming apparatus is not limited to this and may be a monochrome laser printer. Also, the image forming apparatus is not limited to a printer and may be a multifunction machine or a copier.
[0100] (2) In the above embodiments, the relay 108 is used as a switching circuit for switching between supplying and stopping the DC 24V voltage to the high-voltage power supply board 112. However, the switching circuit is not limited to a contact relay, and a semiconductor such as a FET may be used. In short, it is sufficient if the supply and stopping of the DC 24V voltage to the high-voltage power supply board can be switched by the output of the AND circuit 107.
[0101] (3) In each of the above embodiments, the discharge count counter and the discharge flag are configured and stored using the respective registers of the main control circuit 101 and the sub-control circuit 105, but this is not limiting and they may be configured and stored using different storage areas on the RAM 103. In this case, it goes without saying that in addition to the main control circuit 101, the sub-control circuit 105 can also access the storage area on the RAM 103 to read and write the stored contents.
[0102] (4) In the above embodiments, abnormal discharge such as over-discharge in any of the four chargers 32 is described. However, abnormal discharge may be detected not only in the chargers 32 but also on the path of the high-voltage power supply board 112.
[0103] (5) In the above embodiments, the control process program of Fig. 4 is stored in ROM 102 and read into RAM 103 for execution, and the control process program of Fig. 5 is stored in the sub-control circuit 105 and executed as is, but this is not limiting, and the control process program of Fig. 5 may also be stored in ROM 102 and the sub-control circuit 105 may read it into RAM 103 for execution. Also, the control process program stored in ROM 102 may be executed as is without being read into RAM 103. Furthermore, the control process program may be stored in non-volatile memory 104 instead of ROM 102. [Explanation of symbols]
[0104] 1...color laser printer, 20...image forming section, 31...photosensitive drum, 32...charger, 40...exposure section, 100, 100'...main board, 101...main control circuit (first control section), 102...ROM, 103...RAM, 104...non-volatile memory, 105...sub-control circuit (second control section), 106...DC-DC converter, 107...AND circuit (instruction circuit), 108...relay, 112...high-voltage power supply board, 113...low-voltage power supply board (low-voltage power supply circuit).
Claims
1. an image forming unit that forms an image on a sheet; a high-voltage power supply board that applies a high voltage to the image forming unit based on a supplied voltage, the high-voltage power supply board detecting an overcurrent flowing in the image forming unit and outputting a discharge detection signal; a switching circuit for switching between supplying and stopping the voltage to the high-voltage power supply board; a first control unit to which the discharge detection signal is input; a second control unit that controls the high voltage by outputting a control signal to the high voltage power supply board, the second control unit receiving the discharge detection signal; Equipped with The first control unit is a first determination process for determining whether or not an abnormal discharge is occurring in the image forming unit based on the input discharge detection signal; a first instruction process for instructing the switching circuit to stop the supply of the voltage to the high-voltage power supply board when it is determined in the first determination process that an abnormal discharge has occurred in the image forming unit; Run The second control unit is a second determination process for determining whether or not an abnormal discharge is occurring in the image forming unit based on the input discharge detection signal; a second instruction process for instructing the switching circuit to stop the supply of the voltage to the high-voltage power supply board when it is determined in the second determination process that an abnormal discharge has occurred in the image forming unit; Execute 1. An image forming apparatus comprising:
2. The first control unit is In the first determination process, the number of times that the discharge detection signal is input is counted, and if the counted number is equal to or greater than a predetermined number, it is determined that an abnormal discharge has occurred in the image forming unit, and first information indicating that the first control unit has determined that the abnormal discharge has occurred is set; The second control unit is In the second determination process, the number of times the discharge detection signal is input is counted, and if the counted number is equal to or greater than a predetermined number, it is determined that an abnormal discharge has occurred in the image forming unit, and second information indicating that the second control unit has determined that the abnormal discharge has occurred is set.
2. The image forming apparatus according to claim 1,
3. The first control unit is After executing the first instruction process, it is determined whether or not the second information is set, and if the second information is not set, an instruction to initialize the second control unit is given.
3. The image forming apparatus according to claim 2,
4. The second control unit is After executing the second instruction process, it is determined whether or not the first information is set, and if the first information is not set, an instruction to initialize the first control unit is given.
3. The image forming apparatus according to claim 2,
5. an instruction circuit to which an instruction by the first instruction process and an instruction by the second instruction process are input, the instruction circuit instructing the switching circuit to stop the supply of the voltage to the high-voltage power supply substrate when at least one of the instruction by the first instruction process and the instruction by the second instruction process is input; 2. The image forming apparatus according to claim 1, further comprising:
6. The first control unit is outputting a deep sleep signal for causing the image forming apparatus to transition to a deep sleep state when a predetermined condition is satisfied, including when it is determined in the first determination process that an abnormal discharge has occurred in the image forming unit; The deep sleep signal is input to the instruction circuit instead of the instruction by the first instruction process, and when at least one of the deep sleep signal and the instruction by the second instruction process is input, the instruction circuit instructs the switching circuit to stop the voltage to the high-voltage power supply board.
6. The image forming apparatus according to claim 5,
7. a low-voltage power supply circuit for supplying the voltage to the high-voltage power supply board; Further equipped with The deep sleep signal is a signal that instructs the low-voltage power supply circuit to supply a voltage lower than the voltage.
7. The image forming apparatus according to claim 6,
8. The image forming unit includes: A photoconductor drum; A charger that charges the photosensitive drum; an exposure unit that forms an electrostatic latent image on the photosensitive drum that has been charged by the charger; having the abnormal discharge in the image forming unit is an abnormal discharge in the charger, 2. The image forming apparatus according to claim 1,
9. The first control unit is After executing the first instruction process, the device attempts to communicate with the second control unit, and if the device is unable to communicate with the second control unit, instructs the second control unit to perform initialization.
2. The image forming apparatus according to claim 1,
10. The second control unit is After executing the second instruction process, the device attempts to communicate with the first control unit, and if the device is unable to communicate with the first control unit, instructs the first control unit to perform initialization.
2. The image forming apparatus according to claim 1,
Citation Information
Patent Citations
Image-forming apparatus
JP2010197969A