JP2024033269A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that can encourage a user to perform an operation to avoid abnormality before an abnormality occurs in a scorotron electrifier.

SOLUTION: When an ASIC detects that scorotron electrifiers (41) include new articles and old articles before executing image forming processing of forming an image on a sheet, it executes notification processing of notifying information for promoting cleaning of wires (42), and when the ASIC detects that all the scorotron electrifiers (41) are new articles or that all the scorotron electrifiers (41) are old articles, it does not execute the notification processing.

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2024,JPO&INPIT

Description

The present disclosure relates to an image forming apparatus.

Patent Document 1 discloses an image forming apparatus that includes a plurality of charging means arranged to face a plurality of photoreceptors, respectively, and a high-voltage power supply section that applies high voltage to the charging means. The image forming apparatus disclosed in Patent Document 1 detects an abnormality in the charging means by detecting discharge of the charging means using a discharge detection means.

Japanese Patent Application Publication No. 2007-178595

The image forming apparatus disclosed in Patent Document 1 can detect that an abnormality has occurred in the charging means, but it cannot prompt the user to perform an operation to avoid the abnormality in the charging means before the abnormality occurs in the charging means. Can not. An object of the present disclosure is to provide an image forming apparatus that can prompt a user to perform an operation to avoid an abnormality before an abnormality occurs in a scorotron charger.

In order to solve the above problems, an image forming apparatus of the present disclosure includes a first photoreceptor, a first scorotron charger that charges the first photoreceptor, and a first scorotron charger that has a first grid and a first wire. A first photoconductor cartridge having a first scorotron charger, a first memory, a second photoconductor, and a second scorotron charger for charging the second photoconductor, the cartridge including a second grid and a second wire. a second scorotron charger having a second scorotron charger, a second photoreceptor cartridge having a second memory, and a control section, the control section controlling the first scorotron charger and the second scorotron charger; A detection process for detecting whether the first scorotron charger is a new product or an old product, the first history information indicating the usage history of the first photoreceptor cartridge being read from the first memory. By detecting whether the second scorotron charger is new or old, and reading second history information indicating the usage history of the second photoreceptor cartridge from the second memory, the second scorotron charger is detected as new or old. or an old product, and before performing an image forming process of forming an image on the sheet, the first scorotron charger and the second scorotron charger , when it is detected that new and old wires are mixed, a notification process is executed to notify information prompting cleaning of the wire, and before executing the image forming process, the first scorotron charger and If it is detected that both the second scorotron chargers are new, or that both the first scorotron charger and the second scorotron charger are old, the notification process is not executed.

If the Scorotron charger is used for a long period of time, foreign matter may adhere to the wire. Regarding the first scorotron charger and the second scorotron charger, if there is a mixture of new products with no foreign matter attached to the wire and old products with foreign matter attached to the wire, cleaning the wires is recommended. It is preferable that the wire of the first scorotron charger and the wire of the second scorotron charger be in a state where there is no large difference in the degree of adhesion of foreign matter.

According to the image forming apparatus of the present disclosure, when the control unit detects that new and old scorotron chargers are mixed in the first scorotron charger and the second scorotron charger, the control unit sends information prompting cleaning of the wire. Notify to encourage wire cleaning. As a result, the image forming apparatus can prompt the user to perform wire cleaning at a favorable timing, and provide an image forming apparatus that can prompt the user to perform an operation to avoid an abnormality before an abnormality occurs in the scorotron charger. be able to.

Further, the control unit easily detects whether the first scorotron charger and the second scorotron charger are new or old by a simple process of reading history information from the first memory and the second memory. be able to.

The image forming apparatus of the present disclosure includes: a wire voltage application unit that applies a voltage to the first wire and the second wire; a voltage measurement unit that measures the voltage applied to the first wire and the second wire; The control unit further includes, before executing the image forming process, a first application process of applying a voltage to the first wire and the second wire by the wire voltage application unit, and a first application process of applying a voltage to the first wire and the second wire by the voltage measurement unit. , a first measurement process of measuring a first wire voltage applied to the first wire in the first application process and a second wire voltage applied to the second wire in the first application process; further executes, detecting in the detection process that the first scorotron charger is new and that the second scorotron charger is an old product, and detecting that the first scorotron charger is an old product, and the first scorotron charger measured in the first measurement process. If the difference between the wire voltage and the second wire voltage is greater than or equal to the threshold, the notification process is executed, and the detection process determines that the first scorotron charger is new and that the second scorotron charger is old. If the difference between the first wire voltage and the second wire voltage measured by the first measurement process is smaller than the threshold value, the notification process may not be performed. .

If the difference between the first wire voltage and the second wire voltage measured by the first measurement process is smaller than the threshold, a scorotron charger with foreign matter attached to the wire and a scorotron charger with no foreign matter attached to the wire, It is unlikely that they are mixed. Therefore, there is little need to clean the first wire and the second wire.

The control unit executes the notification process when the difference between the first wire voltage and the second wire voltage is equal to or greater than the threshold value, and does not execute the notification process when the difference is small. Thereby, when it is necessary to perform wire cleaning, the control unit can execute notification processing.

The image forming apparatus of the present disclosure includes a wire voltage applying unit that applies a voltage to the first wire and the second wire, a current that measures a current flowing through the first grid, and a current flowing through the second grid. A measurement unit, the control unit includes a first application process of applying a voltage to the first wire and the second wire by the wire voltage application unit before executing the image forming process; a second measurement process of measuring a first grid current flowing to the first grid and a second grid current flowing to the second grid by the current measurement unit when the first application process is executed; further executed, detecting in the detection process that the first scorotron charger is new and that the second scorotron charger is an old product, and the first grid measured in the second measurement process; If the difference between the current and the second grid current is equal to or greater than the threshold, the notification process is executed, and in the detection process it is determined that the first scorotron charger is new and that the second scorotron charger is an old product. If it is detected that this is the case, and the difference between the first grid current and the second grid current measured by the second measurement process is smaller than the threshold value, it is not necessary to perform the notification process.

If the difference between the first grid current and the second grid current measured by the second measurement process is smaller than the threshold, a scorotron charger with foreign matter attached to the wire and a scorotron charger with no foreign matter attached to the wire, It is unlikely that they are mixed. Therefore, there is little need to clean the first wire and the second wire.

The control unit executes the notification process when the difference between the first grid current and the second grid current is equal to or greater than the threshold value, and does not execute the notification process when the difference is small. Thereby, when it is necessary to perform wire cleaning, the control unit can execute notification processing.

The image forming apparatus of the present disclosure further includes a cover that covers the first photoreceptor cartridge and the second photoreceptor cartridge, and a cover sensor that detects opening/closing of the cover, and the control unit controls the notification process. After execution, if the cover sensor detects that the cover is closed, a first determination process may be further executed in which it is determined that the wire cleaning has been performed.

When a user cleans the first wire and the second wire, it is necessary to open and close the cover. Therefore, when the cover is closed, there is a high possibility that the wire has been cleaned by the user. Therefore, when the cover sensor detects that the cover is closed, the control unit can easily determine that the wire cleaning has been performed.

The image forming apparatus of the present disclosure includes: a wire voltage application unit that applies a voltage to the first wire and the second wire; a voltage measurement unit that measures the voltage applied to the first wire and the second wire; The control section further includes a second application of applying a voltage to the first wire and the second wire by the wire voltage application section after executing the notification process and before executing the image forming process. and a first starting voltage, which is a voltage at which the first wire starts corona discharge, and a second starting voltage, which is a voltage at which the second wire starts corona discharge, by the voltage measurement unit. A third measurement process and a second determination process of determining whether or not the wire has been cleaned based on the first start voltage and the second start voltage may be further executed.

By having the user clean the wire, foreign matter attached to the old wire can be removed. When the foreign matter attached to the old wire is removed, the voltage that initiates corona discharge in the old wire decreases.

Here, the second determination process is a process of determining whether the first wire and the second wire have been cleaned based on the first start voltage and the second start voltage, which are the voltages that start corona discharge. . Therefore, the control unit can accurately determine whether the first scorotron charger and the second scorotron charger have been cleaned by the second determination process.

In the image forming apparatus of the present disclosure, the information that prompts the cleaning of the wire notified in the notification process is information that prompts the cleaning of the first wire and the second wire, or the information that prompts the cleaning of the first scorotron charger and the second wire. The information may also be information that prompts cleaning of the wire of a scorotron charger detected to be an old one among the scorotron chargers.

The image forming apparatus of the present disclosure may be realized by a computer, and in this case, the image forming apparatus is realized by a computer by operating the computer as each part included in the image forming apparatus, that is, as a software element. A control program for an image forming apparatus and a computer-readable recording medium on which the program is recorded also fall within the scope of the present disclosure.

According to one aspect of the present disclosure, it is possible to provide an image forming apparatus that can prompt a user to perform an operation to avoid an abnormality before an abnormality occurs in a scorotron charger.

1 is a cross-sectional view showing an example of a schematic configuration of an image forming apparatus according to Embodiment 1 of the present disclosure. 2 is an example of a circuit diagram showing the electrical configuration of the image forming apparatus shown in FIG. 1. FIG. 2 is an example of a circuit diagram showing the electrical configuration of the image forming apparatus shown in FIG. 1. FIG. 2 is a flowchart showing detection processing and notification processing executed by the ASIC of the image forming apparatus shown in FIG. 1. FIG. 7 is a flowchart illustrating image forming processing executed by the ASIC of the image forming apparatus according to Embodiment 2 of the present disclosure. 7 is a flowchart illustrating detection processing and notification processing executed by the ASIC of the image forming apparatus according to Embodiment 2 of the present disclosure. 12 is a flowchart illustrating detection processing and notification processing executed by the ASIC of the image forming apparatus according to Embodiment 3 of the present disclosure. 8 is a flowchart showing voltage measurement processing among the processing shown in FIG. 7. FIG. 12 is a flowchart illustrating detection processing and notification processing executed by the ASIC of the image forming apparatus according to Embodiment 4 of the present disclosure. 10 is a flowchart showing current measurement processing among the processing shown in FIG. 9. 12 is a flowchart showing image forming processing executed by an ASIC of an image forming apparatus according to Embodiment 5 of the present disclosure. 12 is a flowchart illustrating detection processing executed by an ASIC of an image forming apparatus according to Embodiment 5 of the present disclosure. 13 is a flowchart showing voltage calculation processing among the processing shown in FIG. 12. FIG. It is a graph showing the relationship between the current value of the grid current and the value obtained by subtracting the grid voltage from the voltage of the wire.

[Embodiment 1]
<Configuration of image forming apparatus 1>
FIG. 1 is a cross-sectional view showing an example of a schematic configuration of an image forming apparatus 1 according to Embodiment 1 of the present disclosure. The image forming apparatus 1 is a color laser printer that forms a color image on a sheet P. Note that the image forming apparatus 1 may be an MFP (Multi Function Printer) that also has other functions such as a scanner or a facsimile. Further, the sheet P is not limited to plain paper, but may be thick paper, thin paper, or the like. In FIG. 1, the direction from the photoconductor 31Y to the photoconductor 31K is the X-axis direction, the direction from the housing 3 to the cover 7 is the Z-axis direction, and the direction perpendicular to both the X-axis direction and the Z-axis direction is the Y-axis direction. In the axial direction.

As shown in FIG. 1, the image forming apparatus 1 includes a housing 3, a discharge tray 5, a cover 7, a display section 8, a paper feed section 10, an image forming section 20, and a cover sensor 40. Be prepared. The housing 3 is open in the positive direction of the Z-axis, and accommodates the paper feed section 10 and the image forming section 20. The ejection tray 5 is provided on the upper surface of the cover 7. The sheet P on which the image is formed is discharged onto the discharge tray 5.

The cover 7 is rotatably connected to the housing 3 via the hinge part 4 so as to close the opening of the housing 3. The cover 7 covers the image forming section 20. The cover sensor 40 is attached to the inner wall of the housing 3 and detects whether the cover 7 is opened or closed. The display section 8 is provided at the upper part of the cover 7 on the positive side of the X-axis, and includes a display screen, an operation section, and the like. The display unit 8 displays messages to be notified to the user.

<Configuration of image forming section 20>
The image forming section 20 includes a transport unit 21, four process cartridges 30Y, 30M, 30C, and 30K, an exposure section 35, and a fixing section 50. The transport unit 21 is provided between the paper feed section 10 and the process cartridge 30, and includes a transport belt 23 and four transfer rollers 25Y, 25M, 25C, and 25K.

The conveyor belt 23 is an endless belt formed into a ring shape, and is wound around a driving roller 27 and a driven roller 28 . The surface of the conveyor belt 23 on the Z-axis positive direction side extends substantially horizontally directly below the process cartridge 30C and the like, and comes into contact with the back surface of the sheet P fed by the paper feed section 10.

The drive roller 27 rotates the conveyor belt 23 in a predetermined direction. As the conveyor belt 23 rotates, the driven roller 28 also rotates. The transfer rollers 25Y, 25M, 25C, and 25K are charged by application of a transfer voltage, and convey the sheet P along the conveyance path R in the positive direction of the X-axis while attracting the sheet P with electrostatic force.

In the conveyance path R along which the sheet P is conveyed, four process cartridges 30Y and 30M corresponding to each color of yellow (Y), magenta (M), cyan (C), and black (K) are installed in order from the upstream side in the conveyance direction. , 30C, and 30K are arranged. Note that the arrangement order of the process cartridges 30Y, 30M, 30C, and 30K is not limited to this, and can be changed as appropriate.

In the present disclosure, "Y", "M", "C", and "K" in the member numbers mean that each member corresponds to each color mentioned above. In addition, if there is no particular distinction as to which color the component corresponds to, part or all of the component may be indicated by a component number without the addition of "Y," "M," "C," or "K." .

Each of the process cartridges 30Y, 30M, 30C, and 30K includes four photoreceptor cartridges 32Y, 32M, 32C, and 32K corresponding to each color, and four toner cartridges 33Y, 33M, 33C, and 33K corresponding to each color. The process cartridges 30Y, 30M, 30C, and 30K are each provided in the image forming apparatus 1 so that they can be replaced separately.

The toner cartridges 33Y, 33M, 33C, and 33K each contain toner of a corresponding color. The toner cartridges 33Y, 33M, 33C, and 33K are separately replaceably provided in the process cartridges 30Y, 30M, 30C, and 30K, respectively. The photoreceptor cartridge 32K is an example of a first photoreceptor cartridge, and the photoreceptor cartridges 32Y, 32M, and 32C are examples of second photoreceptor cartridges.

Each of the photoreceptor cartridges 32Y, 32M, 32C, and 32K includes a drum-shaped photoreceptor 31Y, 31M, 31C, and 31K, and four scorotron chargers 41Y, 41M, 41C, and 41K. Further, the photoreceptor cartridges 32Y, 32M, 32C, and 32K each have drum memories 34Y, 34M, 34C, and 34K, and are provided to be replaceable separately in the process cartridges 30Y, 30M, 30C, and 30K.

The photoreceptor 31K is an example of a first photoreceptor, and the photoreceptors 31Y, 31M, and 31C are examples of second photoreceptors. The scorotron charger 41K is an example of a first scorotron charger, and the scorotron chargers 41Y, 41M, and 41C are examples of second scorotron chargers. The drum memory 34K is an example of a first memory, and the drum memories 34Y, 34M, and 34C are examples of a second memory.

The drum memories 34Y, 34M, 34C, and 34K are, for example, RAM (Random Access Memory) or IC (Integrated Circuit) chips. The drum memories 34Y, 34M, 34C, and 34K each store history information indicating the usage history of the photoreceptor cartridges 32Y, 32M, 32C, and 32K. History information indicating the usage history of the photoreceptor cartridge 32K is an example of first history information, and history information indicating the usage history of the photoreceptor cartridges 32Y, 32M, and 32C is an example of second history information.

Photoreceptors 31Y, 31M, 31C, and 31K are provided facing transfer rollers 25Y, 25M, 25C, and 25K. The scorotron chargers 41Y, 41M, 41C, and 41K uniformly and positively charge the surfaces of the corresponding photoreceptors 31Y, 31M, 31C, and 31K during image formation.

The exposure section 35 is provided inside the cover 7, and forms electrostatic latent images based on image data on the surfaces of the charged photoreceptors 31Y, 31M, 31C, and 31K. The toner cartridges 33Y, 33M, 33C, and 33K supply toner to the surfaces of the corresponding photoreceptors 31Y, 31M, 31C, and 31K by carrying the toner on the surface of the developing roller 47.

By rotating while being supplied with a developing voltage, the developing roller 47 triboelectrically charges the toner in the toner cartridges 33Y, 33M, 33C, and 33K by friction accompanying the rotation, and transfers the toner to the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K. supply By supplying toner to the electrostatic latent images formed on the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K, toner images are formed on the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K.

The conveyance unit 21 conveys the sheet P toward the fixing section 50. The sheet P is conveyed while being held between transfer rollers 25Y, 25M, 25C, and 25K to which a transfer voltage is applied, and photoreceptors 31Y, 31M, 31C, and 31K. As a result, the toner images developed on the surfaces of the photoreceptors 31Y, 31M, 31C, and 31K are transferred onto the sheet P.

The fixing unit 50 is provided on the downstream side of the transport path R than the transport unit 21 . The fixing section 50 includes a heating roller 51 and a pressure roller 52. The heating roller 51 is disposed on the image forming surface side of the sheet P, rotates in synchronization with the conveyance belt 23, etc., and conveys the sheet P while heating the toner transferred to the sheet P.

The pressure roller 52 sandwiches the sheet P between it and the heating roller 51 and rotates drivenly while pressing the sheet P toward the heating roller 51 side. As a result, the fixing unit 50 heats and melts the toner transferred to the sheet P, thereby fixing it onto the sheet P. The sheet P to which the toner has been fixed by the fixing unit 50 is conveyed along the conveyance path R and is discharged to the discharge tray 5 .

The paper feeding section 10 includes a paper feeding tray 11 containing sheets P and various rollers, and feeds the sheets P to the image forming section 20 by driving the various rollers. Further, the paper feed tray 11 is configured to be detachable from the lower part of the housing 3.

<Electrical configuration of image forming apparatus 1>
2 and 3 are examples of circuit diagrams showing the electrical configuration of the image forming apparatus 1 shown in FIG. 1. FIG. FIG. 2 shows an electric circuit 60 used for forming yellow, magenta, and cyan portions of an image formed by the image forming apparatus 1. As shown in FIG. FIG. 3 shows an electric circuit 60K used to form a black portion of an image formed by the image forming apparatus 1. As shown in FIG.

The image forming apparatus 1 includes an electric circuit 60 and an electric circuit 60K. As shown in FIG. 2, the electric circuit 60 includes an ASIC (Application Specific Integrated Circuit) 61, a high voltage power supply board 62, a ROM 63, and a RAM 64. Further, the electric circuit 60 includes a first voltage application circuit 70, a first charged voltage measurement circuit 78, and grid voltage adjustment circuits 81Y, 81M, and 81C. Note that the electric circuit 60 may include an NVRAM (Non-Volatile Random Access Memory) instead of the ROM 63. In this case, the information stored in the ROM 63 in the following description is stored in the NVRAM.

The ASIC 61 is an example of a control unit that controls the entire image forming apparatus 1 in addition to controlling the high voltage power supply board 62 and the like. The ASIC 61 executes various processes by executing programs stored in the ROM 63, for example. The ASIC 61 is connected to a high voltage power supply board 62, a ROM 63, and a RAM 64.

The high voltage power supply board 62 is provided with a first voltage application circuit 70, a first charged voltage measurement circuit 78, and grid voltage adjustment circuits 81Y, 81M, and 81C. Although the illustration of a part of the configuration is simplified, the grid voltage adjustment circuits 81M and 81C have the same configuration as the grid voltage adjustment circuit 81Y.

The first voltage application circuit 70 is an example of a wire voltage application section, and is connected to the scorotron chargers 41Y, 41M, and 41C via a power line PL. The scorotron charger 41Y has a wire 42Y and a grid 43Y. Similarly, the scorotron charger 41M has a wire 42M and a grid 43M, and the scorotron charger 41C has a wire 42C and a grid 43C. Wires 42Y, 42M, and 42C are examples of second wires, and grids 43Y, 43M, and 43C are examples of second grids.

The first voltage application circuit 70 is connected to the wires 42Y, 42M, and 42C via the power line PL, generates a charging voltage CHG, and applies the voltage to the wires 42Y, 42M, and 42C. Scorotron chargers 41Y, 41M, and 41C are connected in parallel to the power line PL. The charging voltage CHG is, for example, about 5.5 kV or more and 7 kV or less. Further, the first voltage application circuit 70 includes a PWM signal control circuit 71, a transformer drive circuit 72, and a booster circuit 73.

The PWM signal control circuit 71 includes, for example, a resistor and a capacitor (not shown), smoothes a PWM (Pulse Width Modulation) signal Sp1 input from a port PWM1 of the ASIC 61, and supplies the smoothed PWM signal Sp1 to the transdrive circuit 72. do. The transformer drive circuit 72 supplies, for example, the smoothed PWM signal Sp1 supplied from the PWM signal control circuit 71 to a drive transistor (not shown), and supplies an oscillation current to the boost circuit 73.

Boost circuit 73 includes a transformer 74 , a rectifier diode 75 , a smoothing capacitor 76 , and an output resistor 77 . The transformer 74 has a primary winding 74a, a secondary winding 74b, and an auxiliary winding 74c. The transformer drive circuit 72 supplies an oscillation current from a drive transistor to the primary winding 74a.

The transformer 74 changes the voltage value of the charging voltage CHG, which is the output voltage output from the secondary winding 74b, according to the duty ratio of the oscillation current. For example, the transformer 74 generates a charging voltage CHG whose voltage value increases as the duty ratio of the PWM signal Sp1 increases.

A rectifier diode 75, a smoothing capacitor 76, and an output resistor 77 are connected to the secondary winding 74b. Thereby, the booster circuit 73 boosts and rectifies the voltage generated in the primary winding 74a, and applies the charging voltage CHG to the wires 42Y, 42M, and 42C.

The first charged voltage measurement circuit 78 is an example of a voltage measurement section, and is connected between the auxiliary winding 74c and the ASIC 61. The first charged voltage measurement circuit 78 includes, for example, a smoothing circuit and a voltage dividing resistor (not shown). The first charged voltage measurement circuit 78 detects the output voltage V1 generated in the auxiliary winding 74c as the charged voltage CHG is generated.

The first charged voltage measurement circuit 78 is a circuit that measures the voltage applied to the wires 42Y, 42M, and 42C by detecting the charged voltage CHG. The first charged voltage measurement circuit 78 smoothes and divides the output voltage V1, and supplies it to the port A/D1 of the ASIC 61 as an output voltage detection signal Sv1 indicating the charged voltage CHG.

Grid voltage adjustment circuits 81Y, 81M, and 81C are provided corresponding to scorotron chargers 41Y, 41M, and 41C, respectively, and operate according to PWM signals Spp1, Spp2, and Spp3 supplied from ASIC 61. The grid voltage adjustment circuit 81Y includes a grid current measurement circuit 82Y, a grid voltage measurement circuit 83Y, and an operational amplifier OP1.

The grid voltage measurement circuit 83Y has two voltage dividing resistors R7 and R8 connected in series. A shunt current Id1 of the grid current IgY flowing through the grid 43Y flows through the voltage dividing resistors R7 and R8. The grid voltage measurement circuit 83Y outputs a detection voltage Vgr1 corresponding to the grid voltage GRID1 applied to the grid 43Y from the connection point between the two voltage dividing resistors R7 and R8.

The grid voltage measurement circuit 83Y supplies the detection voltage Vgr1 as the divided voltage detection signal Sid1 to the operational amplifier OP1 via the output resistor R6. Capacitor C3 configures an RC filter by being connected in parallel with voltage dividing resistor R8.

A port PWM2 of the ASIC 61 is connected to the operational amplifier OP1 via an output resistor R9. Output resistor R9 is grounded via capacitor C4. ASIC61 supplies PWM signal Spp1 from port PWM2 to operational amplifier OP1 via output resistor R9. Therefore, the ASIC 61 is configured to be able to change the reference voltage and the like of the operational amplifier OP1. Note that the operational amplifier OP1 may be configured to receive a fixed value PWM signal Spp1. In this case, the operational amplifier OP1 does not need to be connected to the ASIC 61.

A smoothing circuit including a voltage dividing resistor R4 and a capacitor C2 is connected to the output terminal of the operational amplifier OP1. A connection point of the voltage dividing resistor R4 on the side opposite to the output terminal of the operational amplifier OP1 is grounded via a capacitor C2. Further, the base of a transistor Q1 for making the grid voltage GRID1 a constant voltage is connected to a connection point of the voltage dividing resistor R4 on the side opposite to the output terminal of the operational amplifier OP1.

Transistor Q1 is connected to a voltage control line Ln1 connected to a connection point between voltage dividing resistor R7 and grid 43Y. Transistor Q1 is, for example, an NPN transistor. The collector of transistor Q1 is connected to grid 43Y, and the emitter of transistor Q1 is connected to resistor R3 of grid current measurement circuit 82Y. Note that the transistor Q1 is not limited to a bipolar transistor, and may be, for example, an FET (field effect transistor).

The base current of transistor Q1 is controlled by the output of operational amplifier OP1. The transistor Q1 has a collector resistance that changes depending on the magnitude of the base current, and functions as a variable resistor. The collector resistance is a resistance value obtained by dividing the collector-emitter voltage by the collector current. For example, the collector resistance decreases by increasing the base current, and conversely increases by decreasing the base current. This changes the collector-emitter voltage.

The ASIC 61 executes feedback control based on the detection voltage Vgr1 detected by the grid voltage measurement circuit 83Y. The ASIC 61 changes the PWM signal Spp1 to change the base voltage of the transistor Q1, and changes the grid voltage GRID1. Therefore, the ASIC 61 can change the voltage value of the grid voltage GRID1 to a predetermined target voltage value by changing the duty ratio of the PWM signal Spp1. Note that a capacitor C1 charged with the grid voltage GRID1 is provided between the voltage control line Ln1 and the grid 43Y.

A grid current measuring circuit 82Y that detects a line current Ir1 corresponding to a grid current IgY flowing through the grid 43Y is connected to the voltage control line Ln1. A resistor R3 of the grid current measuring circuit 82Y is connected between the emitter of the transistor Q1 and ground.

The grid current measuring circuit 82Y is an example of a current measuring section, and supplies the positive terminal voltage of the resistor R3 to the port A/D2 of the ASIC 61 as the line voltage detection signal Sir1. Grid current measurement circuit 82Y is a circuit that measures grid current IgY. Grid current IgY is an example of a second grid current. The ASIC 61 calculates the grid current IgY by dividing the positive terminal voltage of the resistor R3 by the resistance value of the resistor R3.

Furthermore, the configurations of grid voltage adjustment circuits 81M and 81C are similar to the configuration of grid voltage adjustment circuit 81Y. Grid voltage adjustment circuits 81M and 81C each have grid current measurement circuits 82M and 82C. Grid current measurement circuits 82M and 82C are examples of current measurement units, respectively, and are circuits that measure grid currents IgM and IgC. Grid current IgM is a current flowing through grid 43M, and grid current IgC is a current flowing through grid 43C. Grid current IgM and grid current IgC are examples of second grid current.

The ASIC 61 receives an output voltage detection signal Sv1 indicating the charging voltage CHG, and line voltage detection signals Sir1, Sir2, and Sir3 for calculating the grid currents IgY, IgM, and IgC, respectively.

The ASIC 61 controls the voltage value of the charging voltage CHG supplied from the first voltage application circuit 70 based on the current values of the grid currents IgY, IgM, and IgC. For example, the ASIC 61 controls the charging voltage CHG based on the grid current Ig having the smallest current value among the three grid currents IgY, IgM, and IgC. Variations occur in increases in the current values of grid currents IgY, IgM, and IgC.

As shown in FIG. 3, the electric circuit 60K has the same function as the electric circuit 60 shown in FIG. 2 regarding image formation in a black portion, which is one predetermined color. This makes it possible to make the configuration used for monochrome printing independent.

The electric circuit 60K includes a high voltage power supply board 62K, a second voltage application circuit 70K, a second charged voltage measurement circuit 78K, and a grid current measurement circuit 82K. Note that the ASIC 61 may be common to the electric circuit 60, or may be configured separately and operated in cooperation with each other.

The high voltage power supply board 62K is provided with a second voltage application circuit 70K, a second charged voltage measurement circuit 78K, and a grid current measurement circuit 82K. Scorotron charger 41K has wire 42K and grid 43K. The wire 42K is an example of a first wire, and the grid 43K is an example of a first grid.

The second voltage application circuit 70K is an example of a wire voltage application section, and is connected to the scorotron charger 41K via a power supply line PLK. The second voltage application circuit 70K is connected to the wire 42K via the power line PLK, generates a charging voltage CHGK, and applies the voltage to the wire 42K. The second voltage application circuit 70K includes a PWM signal control circuit 71K, a transformer drive circuit 72K, and a booster circuit 73K.

The configurations of the PWM signal control circuit 71K, transformer drive circuit 72K, and booster circuit 73K are similar to those of the PWM signal control circuit 71, transformer drive circuit 72, and booster circuit 73, respectively. The PWM signal control circuit 71K smoothes the PWM signal Sp2 input from the port PWM5 of the ASIC 61.

The second charged voltage measurement circuit 78K is an example of a voltage measurement section, and is connected between the booster circuit 73K and the ASIC 61. The second charged voltage measuring circuit 78K includes, for example, a smoothing circuit and a voltage dividing resistor (not shown). The second charged voltage measurement circuit 78K detects the output voltage V2 generated in the booster circuit 73K as the charged voltage CHGK is generated.

The second charged voltage measurement circuit 78K is a circuit that measures the voltage applied to the wire 42K by detecting the charged voltage CHGK. The second charged voltage measurement circuit 78K smoothes and divides the output voltage V2 and supplies it to the port A/D5 of the ASIC 61 as an output voltage detection signal Sv2 indicating the charged voltage CHGK.

Grid current measurement circuit 82K is connected to grid 43K via current detection line Ln4 and resistor R11. A capacitor C1K charged with grid voltage GRID4 is provided between resistor R11 and grid 43K.

A grid current measuring circuit 82K that measures a grid current IgK flowing through the grid 43K is connected to the current detection line Ln4. Resistor R3K of grid current measurement circuit 82K is connected between resistor R11 and ground. Grid current IgK is an example of a first grid current.

The grid current measurement circuit 82K is an example of a current measurement section, and supplies the positive terminal voltage of the resistor R3K to the port A/D6 of the ASIC 61 as a line voltage detection signal Sir4. Grid current measurement circuit 82K is a circuit that measures grid current IgY. The ASIC 61 calculates the grid current IgK by dividing the positive terminal voltage of the resistor R3K by the resistance value of the resistor R3K.

Note that the electric circuit 60K differs from the electric circuit 60 in that it does not include a grid voltage adjustment circuit. This is because in the electric circuit 60K, the grid current IgK flows only through the grid 43K of the scorotron charger 41K, and the grid current IgK can be adjusted to a desired current value only by controlling the charging voltage CHGK.

<Detection processing and notification processing>
FIG. 4 is a flowchart showing detection processing and notification processing executed by the ASIC 61 of the image forming apparatus 1 shown in FIG. The ASIC 61 executes the process shown in FIG. 4 before executing the image forming process of forming an image on the sheet P. After completing the process shown in FIG. 4, the ASIC 61 transitions to a state in which it can execute the image forming process.

As shown in FIG. 4, the ASIC 61 reads history information indicating the usage history of each photoreceptor cartridge 32 from each drum memory 34 (S1). If the drum memory 34 is an IC chip, the ASIC 61 may read the history information using RFID (Radio Frequency Identification).

After reading the history information, the ASIC 61 detects whether each scorotron charger 41 is a new product or an old product (S2). The process in S2 is an example of a detection process. The ASIC 61 reads the history information from each drum memory 34 to detect whether each Scorotron charger 41 is new or old.

Further, the ASIC 61 may detect that the scorotron charger 41 is an old product, for example, when the history information indicates that the scorotron charger 41 is used. Further, the ASIC 61 may detect that the scorotron charger 41 is new if the history information indicates that the scorotron charger 41 is unused.

The ASIC 61 determines whether each scorotron charger 41 is new or not based on the result of detecting whether each scorotron charger 41 is new or old (S3). If the ASIC 61 determines that there is no new scorotron charger 41 (NO in S3), the process ends.

Consider a case where the ASIC 61 determines that there is a new scorotron charger 41 (YES in S3). In this case, the ASIC 61 determines whether all of the scorotron chargers 41 are new or not based on the result of detecting whether each scorotron charger 41 is new or old (S4).

If the ASIC 61 determines that all of the scorotron chargers 41 are new (YES in S4), the process ends. If the ASIC 61 determines that all of the scorotron chargers 41 are not new (NO in S4), that is, as a result of determining whether or not each scorotron charger 41 is new, it determines that new and old products are mixed. Consider the case where In this case, the ASIC 61 executes a notification process to notify information urging cleaning of all wires 42 (S5).

As the notification process, the ASIC 61 executes a display process to display information urging cleaning of all the wires 42 on the display unit 8. Note that the ASIC 61 may display a message asking whether cleaning of all the wires 42 has been completed as the notification process. Further, the ASIC 61 may execute, as the above-mentioned notification process, a voice output process in which a voice of information urging cleaning of all the wires 42 is outputted from a voice output unit (not shown). The audio output section may be included in the image forming apparatus 1.

Moreover, in the case of NO in S4, there are new wires among the wires 42 and old wires among the wires 42. Therefore, in the case of NO in S4, the ASIC 61 has detected that new and old products are mixed in each Scorotron charger 41. The user can manually clean each wire 42.

After executing the notification process in S5, the ASIC 61 determines whether the OK button displayed on the display unit 8 has been pressed by the user's operation on the operation unit (S6). If the ASIC 61 determines that the OK button has been pressed (YES in S6), it ends the process. If the OK button is not pressed (NO in S6), the ASIC 61 determines whether the cover sensor 40 has detected that the cover 7 has been closed (S7).

When the ASIC 61 determines that the cover sensor 40 has detected that the cover 7 has been closed (YES in S7), the ASIC 61 executes a determination process to determine that the wire 42 has been cleaned. The determination process is an example of the first determination process. After the ASIC 61 executes the above determination process, the process ends. When the ASIC 61 determines that the cover sensor 40 has not detected that the cover 7 is closed (NO in S7), the process proceeds to S6.

When the user cleans each wire 42, it is necessary to open and close the cover 7. Therefore, when the cover 7 is closed, there is a high possibility that the wire 42 has been cleaned by the user. Therefore, when the cover sensor 40 detects that the cover 7 is closed, the ASIC 61 can easily determine that the wire 42 has been cleaned.

If NO in S3, the ASIC 61 detects that there is no new scorotron charger 41, that is, all the scorotron chargers 41 are old products. Further, if NO in S3 or YES in S4, the ASIC 61 does not execute the notification process in S5.

In other words, when the ASIC 61 detects that both the first scorotron charger and the second scorotron charger are new, or that both the first scorotron charger and the second scorotron charger are old, the Notification processing is not executed.

In addition, in the notification process of S5, the ASIC 61 may notify information that prompts cleaning of the wire 42 of the scorotron charger 41 detected as an old product in S2. In other words, the information that prompts the cleaning of the wire 42 notified in the notification process of S5 is the information that prompts the cleaning of the first wire and the second wire, or the information that prompts the cleaning of the first scorotron charger and the second scorotron charger. The information may also be information that prompts cleaning of the wire 42 of the scorotron charger 41 that has been detected.

When charging the surface of the photoreceptor 31 with the scorotron charger 41 in the image forming apparatus 1 of the present disclosure, it is necessary to control the voltage of the wire 42 of the scorotron charger 41 within a predetermined range. The lower limit value of the predetermined range of the voltage of the wire 42 is the lower limit voltage of the wire 42 at which a specified lower limit grid current can flow in order to charge the surface of the photoreceptor 31 to a state suitable for image formation. It is.

In order to charge the photoreceptor 31 with the scorotron charger 41, it is necessary to generate corona discharge. Therefore, the lower limit voltage of the wire 42 is higher than the corona discharge starting voltage, which is the voltage of the wire 42 at which corona discharge starts in the scorotron charger 41. The upper limit of the predetermined range of the voltage of the wire 42 is the upper limit voltage of the wire 42 at which the amount of charged products (ozone, nitrogen oxides, etc.) generated from the scorotron charger 41 falls within an allowable range.

When the scorotron charger 41 is used for a long period of time, foreign matter may adhere to the wire 42. The lower limit voltage of the wire 42 of the scorotron charger 41 with foreign matter attached to the wire 42 is higher than the lower limit voltage of the wire 42 of the scorotron charger 41 with no foreign matter attached to the wire 42. If new and old scorotron chargers 41 are used together, the lower limit voltage of the wire 42 of one scorotron charger 41 may exceed the upper limit voltage of the wire 42 of another scorotron charger 41. There is.

For example, consider a case where new and old scorotron chargers 41 coexist in the image forming apparatus 1 configured to apply the same voltage to the wire 42 of each scorotron charger 41 from a common voltage application circuit. In this case, a problem arises in that the voltages applied to the wires 42 of each scorotron charger 41 cannot be kept within a predetermined range at the same time.

If all the wires 42 are cleaned, even if new and old scorotron chargers 41 are mixed, the lower limit voltage of the wire 42 of one scorotron charger 41 will be the same as that of the wire 42 of another scorotron charger 41. This solves the problem of exceeding the upper limit voltage.

However, it is difficult for the user to perform cleaning of the wires 42, which is an operation of determining whether new and old parts of each scorotron charger 41 are mixed and removing foreign matter from each wire 42.

According to the image forming apparatus 1 of the present disclosure, when the ASIC 61 detects that a new product and an old product are mixed for each scorotron charger 41, the ASIC 61 notifies the wire 42 of cleaning the wire 42. encourage cleaning. As a result, the image forming apparatus 1 can prompt the wire 42 to be cleaned at a preferable timing, and the image forming apparatus can prompt the user to perform an operation to avoid an abnormality before an abnormality occurs in the scorotron charger 41. 1 can be provided.

[Embodiment 2]
Embodiment 2 of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in Embodiment 1 will be denoted by the same reference numerals, and the description thereof will not be repeated.

<Image formation processing>
FIG. 5 is a flowchart showing image forming processing executed by the ASIC 61 of the image forming apparatus 1 according to the second embodiment of the present disclosure. As shown in FIG. 5, the ASIC 61 determines whether there is a command to apply voltage to each wire 42 (S10). When the ASIC 61 receives a print job and the process shown in FIG. 6 has been completed, the ASIC 61 receives a voltage application command to each wire 42 and determines that there is the voltage application command. The processing shown in FIG. 6 will be described later.

If there is no command to apply voltage to each wire 42 (NO in S10), the ASIC 61 continues the process in S10. Consider a case where the ASIC 61 determines that there is a command to apply voltage to each wire 42 (YES in S10). In this case, the ASIC 61 executes an application process of applying a voltage to each wire 42 using the first voltage application circuit 70 and the second voltage application circuit 70K in the image forming process (S11).

When executing the application process in S11, the ASIC 61 stores the voltage value of the voltage of the wire 42 corresponding to each color in the RAM 64 at predetermined time intervals (S12). The predetermined time in S12 is, for example, 1 ms. S12 will be specifically explained below.

In S12, the ASIC 61 executes a measurement process of measuring the voltage applied to each wire 42 in the application process of S11 using the first charged voltage measurement circuit 78 and the second charged voltage measurement circuit 78K. Further, in S12, the ASIC 61 stores in the RAM 64 the voltage value of the voltage applied to each wire 42 measured in the measurement process.

After storing the voltage value of the voltage applied to each wire 42 in the RAM 64, the ASIC 61 determines whether the voltage application command to each wire 42 has been completed (S13). If the command to apply voltage to each wire 42 has not been completed (NO in S13), the ASIC 61 continues the process in S13. If the ASIC 61 determines that the voltage application command to each wire 42 has been completed (YES in S13), the ASIC 61 ends the application process of applying voltage to each wire 42 (S14).

<Detection processing and notification processing>
FIG. 6 is a flowchart showing detection processing and notification processing executed by the ASIC 61 of the image forming apparatus 1 according to the second embodiment of the present disclosure. The processes S21 to S23 and S26 to S28 shown in FIG. 6 are the same as the processes S1 to S3 and S5 to S7 shown in FIG. 4, respectively. Consider a case where the ASIC 61 determines that there is a new one among the scorotron chargers 41 (YES in S23). In this case, the ASIC 61 reads the history of the voltage values of the voltages applied to each wire 42 from the RAM 64 (S24).

The ASIC 61 determines whether there is a photoreceptor cartridge 32 in which the voltage of the wire 42 is equal to or higher than a predetermined threshold value based on the history of voltage values read from the RAM 64 (S25). The voltage value that the ASIC 61 reads from the RAM 64 is the voltage value that the ASIC 61 stored in the RAM 64 in S12 shown in FIG. 5 when the ASIC 61 received the print job last time.

If the ASIC 61 determines that there is no photoreceptor cartridge 32 whose voltage on the wire 42 is equal to or higher than the predetermined threshold value (NO in S25), the process ends. If the ASIC 61 determines that there is a photoreceptor cartridge 32 for which the voltage of the wire 42 is equal to or higher than the predetermined threshold value (YES in S25), that is, it detects that each Scorotron charger 41 is a mixture of new and old products. If so, the process of S26 is executed.

The voltage on the old wire 42 is higher than the voltage on the new wire 42. According to the above configuration, the ASIC 61 can determine in S25 whether or not to execute the notification process in S26 based on the voltage applied to each wire 42 in the image forming process.

[Embodiment 3]
Embodiment 3 of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in Embodiments 1 and 2 will be denoted by the same reference numerals, and the description thereof will not be repeated. In the third embodiment, the image forming apparatus 1 includes an electric circuit having four voltage application circuits, four charged voltage measurement circuits, and four grid voltage adjustment circuits corresponding to each color, instead of the electric circuit 60 and the electric circuit 60K. Be prepared.

Each of the above four voltage application circuits is connected to the wires 42Y, 42M, 42C, and 42K in a one-to-one correspondence via power lines, and generates a charged voltage to connect the wires 42Y, 42M, 42C, and 42K. Apply voltage to. Each of the four voltage application circuits described above is an example of a wire voltage application section, and has the same function as the first voltage application circuit 70.

Each of the four charged voltage measurement circuits is a circuit that measures the voltage applied to the wires 42Y, 42M, 42C, and 42K by detecting the charged voltage. The four charged voltage measuring circuits have one-to-one correspondence with the wires 42Y, 42M, 42C, and 42K, respectively. Each of the four charged voltage measurement circuits described above is an example of a voltage measurement section, and has the same function as the first charged voltage measurement circuit 78. Each of the four grid voltage adjustment circuits described above has the same function as the grid voltage adjustment circuit 81Y, and is provided corresponding to each grid 43.

<Detection processing and notification processing>
FIG. 7 is a flowchart showing detection processing and notification processing executed by the ASIC 61 of the image forming apparatus 1 according to the third embodiment of the present disclosure. FIG. 8 is a flowchart showing the voltage measurement process among the processes shown in FIG. In the third embodiment, the image forming process executed by the ASIC 61 is the same as the image forming process shown in FIG. The ASIC 61 executes the process shown in FIG. 7 before executing the image forming process. The processes of S31 to S33 and S36 to S38 shown in FIG. 7 are the same as the processes of S21 to S23 and S26 to S28 shown in FIG. 6, respectively.

Consider a case where the ASIC 61 determines that there is a new one among the scorotron chargers 41 (YES in S33). In this case, as shown in FIG. 7, the ASIC 61 executes voltage measurement processing (S34). The voltage measurement process in S34 will be explained below using FIG. 8.

As shown in FIG. 8, in the voltage measurement process of S34, the ASIC 61 first reads the voltage setting value Vgt of each grid 43 from the ROM 63 (S41). The set value Vgt is stored in advance in the ROM 63 for each grid 43. The set value Vgt is, for example, 200V.

After reading the set value Vgt from the ROM 63, the ASIC 61 executes an application process of applying a voltage to each wire 42 using the four voltage application circuits before executing the image forming process (S42). The application process in S42 is an example of the first application process. When executing the application process in S42, the ASIC 61 supplies PWM signals to the four grid voltage adjustment circuits so that the grid voltage of each grid 43 becomes the set value Vgt.

The set value Vgt is a numerical value lower than the set value of the voltage of each grid 43 when the ASIC 61 executes the application process of S11 shown in FIG. The set value of the voltage of each grid 43 when the ASIC 61 executes the application process in S11 is, for example, 800V.

After executing the application process of S42, the ASIC 61 executes a measurement process of measuring the voltage applied to each wire 42 in the application process of S42 using the four charged voltage measurement circuits (S43). The measurement process in S43 is an example of the first measurement process. Further, the voltage applied to the wire 42K measured in S43 is an example of the first wire voltage, and the voltage applied to the wires 42Y, 42M, and 42C measured in S43 is an example of the second wire voltage. be.

Returning to FIG. 7, after executing the voltage measurement process in S34, the ASIC 61 determines whether Vwold-Vwnew is less than 500V for all old photoconductor cartridges 32 (S35). 500V in S35 is an example of a threshold value. The ASIC 61 executes the process of S35 for every old photoreceptor cartridge 32.

All of the old photoreceptor cartridges 32 in S35 are the photoreceptor cartridges 32 having the scorotron charger 41 determined to be old in S32. Vwold is the voltage of the wire 42 measured in S43 for the scorotron charger 41 determined to be an old product in S32. Vwnew is the voltage of the wire 42 measured in S43 for the scorotron charger 41 determined to be new in S32.

Note that when there are multiple scorotron chargers 41 determined to be new in S32, Vwnew is the value measured in S43 for any one of the multiple scorotron chargers 41 determined to be new. It may be the voltage of the wire 42. Further, in this case, Vwnew may be an average value of the voltages of the plurality of wires 42 measured in S43 for the plurality of scorotron chargers 41 determined to be new.

If the ASIC 61 determines that Vwold-Vwnew is less than 500V for all the old photoconductor cartridges 32 (YES in S35), the process ends. If the ASIC 61 determines that Vwold-Vwnew is not less than 500V for at least one of all the old photoconductor cartridges 32 (NO in S35), that is, the new and old products are mixed for each Scorotron charger 41. If it is detected that this is the case, the process of S36 is executed.

Regarding the above-mentioned process, for example, the ASIC 61 reads history information from each of the plurality of drum memories 34 in S31, and determines in S32 that the scorotron charger 41K is new and that the scorotron chargers 41Y, 41M, and 41C are new. Consider a case where it is detected that the product is an old product.

In this case, in S35, the ASIC 61 determines that if the difference between the voltages of the wires 42Y, 42M, and 42C measured in the measurement process of S43 and the voltage of the wire 42K measured in the measurement process of S43 is equal to or greater than the threshold value, The notification process of S36 is executed. Further, in S35, if the difference between the voltages of the wires 42Y, 42M, and 42C measured in the measurement process of S43 and the voltage of the wire 42K measured in the measurement process of S43 is smaller than the threshold value, the ASIC 61 performs the process of S36. Notification processing is not executed.

That is, the ASIC 61 detects that the first scorotron charger is new and that the second scorotron charger is an old product by reading the first history information from the first memory, and performs the first measurement process. If the difference between the first wire voltage and the second wire voltage measured by is equal to or greater than the threshold value, the notification process is executed. Further, the ASIC 61 detects that the first scorotron charger is new and that the second scorotron charger is an old product by reading the first history information from the first memory, and performs the first measurement process. If the difference between the first wire voltage and the second wire voltage measured by is smaller than the threshold value, the notification process is not executed.

If the difference between the voltages of the wires 42Y, 42M, and 42C measured by the measurement process in S43 and the voltage of the wire 42K of the new Scorotron charger 41K is smaller than the threshold, the Scorotron charger has foreign matter attached to the wire 42. 41 and the scorotron charger 41 with no foreign matter attached to the wire 42 are unlikely to coexist. Therefore, there is little need to clean the wire 42.

The ASIC 61 executes the notification process when the difference between the voltages of the wires 42Y, 42M, and 42C and the voltage of the wire 42K of the new Scorotron charger 41K is equal to or more than a threshold value, and does not execute the notification process when it is small. . Thereby, when the wire 42 needs to be cleaned, the ASIC 61 can perform notification processing.

[Embodiment 4]
Embodiment 4 of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in Embodiments 1 to 3 are denoted by the same reference numerals, and the description thereof will not be repeated. In the fourth embodiment, the image forming apparatus 1 includes an electric circuit having one voltage application circuit, one charged voltage measurement circuit, and four grid voltage adjustment circuits instead of the electric circuit 60 and the electric circuit 60K.

The one voltage application circuit is connected to the wires 42Y, 42M, 42C, and 42K via power supply lines, generates a charging voltage CHG, and applies the voltage to the wires 42Y, 42M, 42C, and 42K. The above-mentioned one voltage application circuit is an example of a wire voltage application section, and has the same function as the first voltage application circuit 70.

Each of the above charged voltage measurement circuits is a circuit that measures the voltages applied to the wires 42Y, 42M, 42C, and 42K by detecting the charged voltage CHG. The above-mentioned one charged voltage measurement circuit is an example of a voltage measurement section, and has the same function as the first charged voltage measurement circuit 78. Each of the four grid voltage adjustment circuits described above has the same function as the grid voltage adjustment circuit 81Y, and is provided corresponding to each grid 43.

<Detection processing and notification processing>
FIG. 9 is a flowchart showing a detection process and a notification process executed by the ASIC 61 of the image forming apparatus 1 according to the fourth embodiment of the present disclosure. FIG. 10 is a flowchart showing the current measurement process among the processes shown in FIG. In the fourth embodiment, the image forming process executed by the ASIC 61 is the same as the image forming process shown in FIG.

The ASIC 61 executes the process shown in FIG. 9 before executing the image forming process. The processes of S51 to S53 and S56 to S58 shown in FIG. 9 are the same as the processes of S21 to S23 and S26 to S28 shown in FIG. 6, respectively. The process of S62 shown in FIG. 10 is the same as the process of S42 shown in FIG.

Consider a case where the ASIC 61 determines that there is a new one among the scorotron chargers 41 (YES in S53). In this case, as shown in FIG. 9, the ASIC 61 executes current measurement processing (S54). The current measurement process in S54 will be described below using FIG. 10.

As shown in FIG. 10, in the current measurement process of S54, the ASIC 61 first calculates the set value Vwt of the voltage of the wire 42 from the voltage value Vwb of the voltage of the wire 42 when executing the application process of S11 shown in FIG. is calculated (S61).

Specifically, the ASIC 61 reads the voltage value Vwb from the RAM 64. The voltage value Vwb is the voltage value that the ASIC 61 stored in the RAM 64 in S12 shown in FIG. 5 when the ASIC 61 received the print job last time. The ASIC 61 calculates a value obtained by subtracting, for example, 1000V from the voltage value Vwb as the set value Vwt.

After calculating the set value Vwt, the ASIC 61 executes the process of S62. When the ASIC 61 executes the process of applying voltage to the wire 42 in S62, the ASIC 61 measures the grid current flowing in each grid 43 using four grid current measuring circuits (S63). The measurement process in S63 is an example of the second measurement process. The four grid current measurement circuits are included in the four grid voltage adjustment circuits, respectively.

Returning to FIG. 9, after executing the current measurement process in S54, the ASIC 61 determines whether Ignew-Igold is less than 100 μA for all old photoconductor cartridges 32 (S55). 100 μA of S55 is an example of a threshold value. The ASIC 61 executes the process of S55 for every old photoreceptor cartridge 32.

All of the old photoreceptor cartridges 32 in S55 are the photoreceptor cartridges 32 having the scorotron charger 41 determined to be old in S52. Ignew is the grid current measured in S63 for the scorotron charger 41 determined to be new in S52. Igold is the grid current measured in S63 for the scorotron charger 41 determined to be an old product in S52.

Note that if there are multiple scorotron chargers 41 determined to be new in S52, Ignew is the value measured in S63 for any one of the multiple scorotron chargers 41 determined to be new. It may also be a grid current. Further, in this case, Ignew may be the average value of the grid currents of the plurality of grids 43 measured in S63 for the plurality of scorotron chargers 41 determined to be new.

If the ASIC 61 determines that Ignew-Igold is less than 100 μA for all the old photoconductor cartridges 32 (YES in S55), the process ends. If the ASIC 61 determines that Ignew-Igold is not less than 100 μA for at least one of all old photoconductor cartridges 32 (NO in S55), that is, new and old products are mixed for each Scorotron charger 41. If it is detected that this is the case, the process of S56 is executed.

Regarding the above-mentioned process, for example, the ASIC 61 reads history information from each of the plurality of drum memories 34 in S51, and determines in S52 that the scorotron charger 41K is new and that the scorotron chargers 41Y, 41M, and 41C are new. Consider a case where it is detected that the product is an old product.

In this case, in S55, if the difference between the grid current IgK measured in the measurement process of S63 and each of the grid currents IgY, IgM, and IgC measured in the measurement process of S63 is equal to or greater than the threshold value, the ASIC 61 performs the process of S56. Execute notification processing. In addition, in S55, if the difference between the grid current IgK measured in the measurement process of S63 and each of the grid currents IgY, IgM, and IgC measured in the measurement process of S63 is smaller than the threshold, the ASIC 61 performs the notification process of S56. do not execute.

That is, by reading the first history information from the first memory, the ASIC 61 detects that the first scorotron charger is new and that the second scorotron charger is an old product, and performs the second measurement process. If the difference between the first grid current and the second grid current measured by is equal to or greater than the threshold value, the notification process is executed. Further, the ASIC 61 detects that the first scorotron charger is new and that the second scorotron charger is an old product by reading the first history information from the first memory, and performs the second measurement process. If the difference between the first grid current and the second grid current measured by is smaller than the threshold value, the notification process is not executed.

If the difference between the grid current IgK and the grid currents IgY, IgM, and IgC measured by the measurement process in S63 is smaller than the threshold value, it is determined that the scorotron charger 41 has foreign matter attached to the wire 42 and the wire 42 has no foreign matter attached. It is unlikely that the scorotron charger 41 is mixed. Therefore, there is little need to clean the wire 42.

The ASIC 61 executes the notification process when the difference between the grid current IgK of the new Scorotron charger 41K and the grid currents IgY, IgM, and IgC is equal to or greater than the threshold value, and does not execute the notification process when it is small. Thereby, when the wire 42 needs to be cleaned, the ASIC 61 can execute notification processing.

[Embodiment 5]
Embodiment 5 of the present disclosure will be described below. For convenience of explanation, members having the same functions as those described in Embodiments 1 to 4 are denoted by the same reference numerals, and the description thereof will not be repeated. In the fifth embodiment, the image forming apparatus 1 includes an electric circuit 60 shown in FIG. 2 and an electric circuit 60K shown in FIG. 3.

<Image formation processing>
FIG. 11 is a flowchart showing image forming processing executed by the ASIC 61 of the image forming apparatus 1 according to the fifth embodiment of the present disclosure. The processes of S71, S72, S74, and S75 shown in FIG. 11 are the same as the processes of S10, S11, S13, and S14 shown in FIG. 5, respectively.

When executing the application process in S72, the ASIC 61 stores the voltage value Vwb of the wire 42, the voltage value Vgb of the grid 43, and the grid current value Igb of the grid 43 in the RAM 64 for the scorotron charger 41 corresponding to each color at predetermined time intervals. It is stored (S73). The predetermined time in S73 is, for example, 1 ms. S73 will be specifically explained below.

In S73, the ASIC 61 executes a measurement process of measuring the voltage applied to each wire 42 in the application process of S72 using the first charged voltage measurement circuit 78 and the second charged voltage measurement circuit 78K. Further, in S73, the ASIC 61 stores in the RAM 64 the voltage value Vwb of the voltage applied to each wire 42 measured in the measurement process.

Further, when the ASIC 61 executes the application process in S72, the grid currents flowing through each grid 43 are measured by the grid current measurement circuits 82Y, 82M, 82C, and 82K. In S73, the ASIC 61 stores the grid current value Igb of the measured grid current in the RAM 64. After the ASIC 61 stores the voltage value Vwb of the wire 42, the voltage value Vgb of the grid 43, and the grid current value Igb in the RAM 64, the process proceeds to S74.

<Detection processing and notification processing>
FIG. 12 is a flowchart showing a detection process executed by the ASIC 61 of the image forming apparatus 1 according to the fifth embodiment of the present disclosure. FIG. 13 is a flowchart showing the voltage calculation process among the processes shown in FIG. 12. FIG. 14 is a graph showing the relationship between the current value of the grid current Ig and the value obtained by subtracting the grid voltage Vg from the voltage Vw of the wire 42. The processing in S84 to S86 shown in FIG. 12 is the same as the processing in S1 to S3 shown in FIG. 4, respectively. Further, the process in S81 shown in FIG. 12 is the same as the process in S7 shown in FIG.

When the ASIC 61 determines that the cover sensor 40 has detected that the cover 7 is closed (YES in S81), the ASIC 61 reads the voltage value Vwb of the voltage of the wire 42 a predetermined time before the end of printing of each color from the RAM 64 (S82). . The predetermined time in S82 is, for example, 120 ms. The voltage value Vwb is the voltage value that the ASIC 61 stored in the RAM 64 in S73 when the ASIC 61 received the print job last time.

After reading the voltage value Vwb from the RAM 64, the ASIC 61 determines whether there is a photoconductor cartridge 32 in which the voltage value Vwb of the voltage of the wire 42 is equal to or higher than a predetermined threshold (S83). If the ASIC 61 determines that there is no photoreceptor cartridge 32 whose voltage value Vwb is equal to or higher than the predetermined threshold value (NO in S83), the process ends. If the ASIC 61 determines that there is a photoreceptor cartridge 32 whose voltage value Vwb is equal to or greater than the predetermined threshold value (YES in S83), it executes the process in S84.

If the ASIC 61 determines that there is a new scorotron charger 41 (YES in S86), it executes a voltage calculation process (S87). The voltage calculation process in S87 will be explained below using FIG. 13. The processes of S91 and S94 shown in FIG. 13 are the same as the processes of S41 and S42 shown in FIG. 8, respectively. Further, the processing in S99 to S101 shown in FIG. 13 is the same as the processing in S5 to S7 shown in FIG. 4, respectively.

After executing the process of S91, the ASIC 61 calculates the set value Vwt of the voltage of each wire 42 (S92). Specifically, the ASIC 61 calculates the set value Vwt using the following equation (1).

Vwt=Vwb-ΔV-(Vgb-Vgt)...(1)
Vwb is the voltage value of the voltage on the wire 42 that the ASIC 61 reads from the RAM 64 in S82. ΔV is, for example, 1000V, and is stored in the ROM 63 in advance. Vgb is the voltage value of the voltage of the grid 43 that the ASIC 61 stored in the RAM 64 in S73 when the ASIC 61 received the print job last time. Vgt is a set value of the voltage of each wire 42 that the ASIC 61 reads from the ROM 63 in S91, and is, for example, 400V.

After calculating the set value Vwt, the ASIC 61 reads the grid voltage Vgkt of the grid 43K from the ROM 63 (S93). The grid voltage Vgkt is, for example, 200V and is stored in the ROM 63 in advance. After reading the grid voltage Vgkt, the ASIC 61 executes the process of S94.

After executing the process of S94, the ASIC 61 stores the set value Vwt of the voltage of the wire 42 corresponding to each color in the RAM 64 (S95). After storing the wire voltage setting value Vwt in the RAM 64, the ASIC 61 calculates the corona discharge starting voltage Vthb during printing corresponding to each color (S96). Specifically, the ASIC 61 calculates the corona discharge starting voltage Vthb using the following equation (2).

Vthb=Vwb-Vgb-Igb×K...(2)
Igb is the current value of the grid current of the grid 43 that the ASIC 61 stored in the RAM 64 in S73 when the ASIC 61 received the print job last time. K is a coefficient stored in advance in the ROM 63, and is, for example, 5. The corona discharge starting voltage Vthb is a voltage at which each wire 42 starts corona discharge when the ASIC 61 executes the application process of S72.

After calculating the corona discharge starting voltage Vthb, the ASIC 61 calculates the corona discharge starting voltage Vtht corresponding to each color (S97). Specifically, the ASIC 61 calculates the corona discharge starting voltage Vtht using the following equation (3). The corona discharge starting voltage Vtht is a voltage value for determining whether or not to execute the notification process of S99.

Vtht=Vwt-Vgt-Igt×K...(3)
Vwt is the set value of the voltage of each wire 42 calculated by the ASIC 61 in S92. Vgt is the grid voltage Vgkt of the grid 43K and the grid voltages of the grids 43Y, 43M, and 43C read by the ASIC 61 in S93. The grid voltages of the grids 43Y, 43M, and 43C are, for example, 400V, and are stored in the ROM 63 in advance.

Igt is the grid current flowing through the grids 43Y, 43M, and 43C measured by the grid current measuring circuits 82Y, 82M, and 82C when the ASIC 61 executes the application process in S94. Moreover, Igt is a set value of the grid current of the grid 43K, which is stored in advance in the ROM 63.

The graph shown in FIG. 14 is obtained using the above equations (2) and (3). Here, regarding the grid current value Igb, it is assumed that the grid current value of the grid 43Y is Igyb, the grid current value of the grid 43M is Igmb, and the grid current value of the grid 43C is Igcb. Further, regarding the voltage value Vwb of the voltage of the wire 42, the voltage value of the wire 42Y is Vwyb, the voltage value of the wire 42M is Vwmb, and the voltage value of the wire 42C is Vwcb.

Further, regarding the corona discharge starting voltage Vthb, the voltage value of the wire 42Y is Vthyb, the voltage value of the wire 42M is Vthmb, and the voltage value of the wire 42C is Vthcb. Vwyt is the set value of the voltage of the wire 42Y with respect to the set value Vwt. Igyt is the grid current setting value of the grid 43Y with respect to the grid current setting value Igt. Vthyt is the corona discharge starting voltage of the wire 42Y with respect to the corona discharge starting voltage Vtht.

The ASIC 61 calculates the set value Vwt in S92 based on the voltage value Vwb of the voltage applied to each wire 42 measured by the first charged voltage measurement circuit 78 and the second charged voltage measurement circuit 78K in S73. The ASIC 61 calculates the corona discharge starting voltage Vtht in S97 based on the calculated setting value Vwt. In this way, the ASIC 61 executes the measurement process of measuring the corona discharge starting voltage Vtht. The measurement process is an example of the third measurement process.

The corona discharge starting voltage Vtht, which is the voltage at which the wire 42K starts corona discharge, is an example of the first starting voltage. The corona discharge starting voltage Vtht, which is the voltage at which the wires 42Y, 42M, and 42C start corona discharge, is an example of the second starting voltage.

After calculating the corona discharge starting voltage Vtht, the ASIC 61 determines whether VthMax-VthMin is less than Vthmaxmin (S98). VthMax is the maximum value among the corona discharge starting voltages Vtht corresponding to each color, and VthMin is the minimum value among the corona discharge starting voltages Vtht corresponding to each color.

If the ASIC 61 determines that VthMax−VthMin is less than Vthmaxmin (YES in S98), the process ends. If the ASIC 61 determines that VthMax-VthMin is not less than Vthmaxmin (NO in S98), that is, if it detects that each Scorotron charger 41 is a mixture of new and old products, it executes the process of S99. .

As described above, the ASIC 61 determines in S98 whether or not to execute the notification process in S99 based on the corona discharge starting voltage Vtht. The voltage that initiates corona discharge in the old wire 42 is higher than the voltage that initiates corona discharge in the new wire 42. The ASIC 61 can determine whether to execute the notification process in S99 based on the corona discharge starting voltage Vtht.

[Modified example]
After the ASIC 61 executes the notification process in S99 and before executing the image forming process shown in FIG. may be executed. The application process is an example of the second application process. Further, after executing the above-mentioned application process, the ASIC 61 executes the above-mentioned third measurement process.

The ASIC 61 executes a determination process to determine whether or not the wire 42 has been cleaned, based on the corona discharge starting voltage Vtht of each wire 42 measured in the third measurement process. The determination process is an example of the second determination process. When the ASIC 61 determines that each wire 42 has been cleaned through the determination process, the ASIC 61 ends the process. When the ASIC 61 determines that each wire 42 has not been cleaned through the above determination process, it executes the process of S99.

By having the user clean the wire 42, foreign matter attached to the old wire 42 can be removed. When the foreign matter attached to the old wire 42 is removed, the voltage at which corona discharge starts in the old wire 42 decreases.

Here, the second determination process is a process of determining whether each wire 42 has been cleaned based on the corona discharge starting voltage Vtht, which is the voltage that starts corona discharge. Therefore, the ASIC 61 can accurately determine whether each scorotron charger 41 has been cleaned by the second determination process.

[Example of implementation using software]
The function of the image forming apparatus 1 (hereinafter referred to as the "apparatus") is a program for making a computer function as the apparatus, which causes the computer to function as each control block of the apparatus (particularly each part included in the ASIC 61). This can be achieved using a program for

In this case, the device includes a computer having at least one control device (for example, a processor) and at least one storage device (for example, a memory) as hardware for executing the program. By executing the above program using this control device and storage device, each function described in each of the above embodiments is realized.

The above program may be recorded on one or more computer-readable recording media instead of temporary. This recording medium may or may not be included in the above device. In the latter case, the program may be supplied to the device via any transmission medium, wired or wireless.

Further, part or all of the functions of each of the control blocks described above can also be realized by a logic circuit. For example, an integrated circuit in which a logic circuit functioning as each of the control blocks described above is formed is also included in the scope of the present disclosure. In addition to this, it is also possible to realize the functions of each of the control blocks described above using, for example, a quantum computer.

The present disclosure is not limited to the embodiments described above, and various changes can be made within the scope of the claims, and embodiments obtained by appropriately combining technical means disclosed in different embodiments. are also included within the technical scope of the present disclosure.

1 Image forming device 7 Cover 31, 31Y, 31M, 31C, 31K Photoconductor 32, 32Y, 32M, 32C, 32K Photoconductor cartridge 34, 34Y, 34M, 34C, 34K Drum memory 40 Cover sensor 41, 41Y, 41M, 41C , 41K Scorotron charger 42, 42Y, 42M, 42C, 42K Wire 43, 43Y, 43M, 43C, 43K Grid 61 ASIC
70 First voltage application circuit 70K Second voltage application circuit 78 First charged voltage measurement circuit 78K Second charged voltage measurement circuit 82K Grid current measurement circuit 83Y Grid voltage measurement circuit Vtht Corona discharge starting voltage

Claims (6)

a first photoreceptor;
a first scorotron charger that charges the first photoreceptor, the first scorotron charger having a first grid and a first wire; a first memory;
a first photoreceptor cartridge having;
a second photoreceptor;
a second scorotron charger that charges the second photoreceptor, the second scorotron charger having a second grid and a second wire; a second memory;
a second photoreceptor cartridge having;
comprising a control unit;
The control unit includes:
Detection processing for detecting whether the first scorotron charger and the second scorotron charger are new or old,
detecting whether the first scorotron charger is a new product or an old product by reading first history information indicating a usage history of the first photoreceptor cartridge from the first memory;
and detecting whether the second scorotron charger is a new product or an old product by reading second history information indicating a usage history of the second photoreceptor cartridge from the second memory. Execute the detection process,
If it is detected that new and old parts of the first scorotron charger and the second scorotron charger are mixed before performing an image forming process of forming an image on the sheet, cleaning the wires is performed. Execute notification processing to notify the prompting information,
Before executing the image forming process, both the first scorotron charger and the second scorotron charger are new, or both the first scorotron charger and the second scorotron charger are old products. An image forming apparatus characterized in that the image forming apparatus does not execute the notification process when it detects that the image forming apparatus has the following information. a wire voltage application unit that applies voltage to the first wire and the second wire;
further comprising a voltage measuring unit that measures the voltage applied to the first wire and the second wire,
The control unit includes:
a first application process of applying a voltage to the first wire and the second wire by the wire voltage application unit before executing the image forming process;
A first wire voltage applied to the first wire in the first application process and a second wire voltage applied to the second wire in the first application process by the voltage measurement unit. 1 measurement processing, and
In the detection process, it is detected that the first scorotron charger is new and that the second scorotron charger is an old product, and the first wire voltage measured in the first measurement process and the second scorotron charger are If the difference with the 2-wire voltage is equal to or greater than the threshold, execute the notification process,
In the detection process, it is detected that the first scorotron charger is new and that the second scorotron charger is an old product, and the first wire voltage measured in the first measurement process and the second scorotron charger are 2. The image forming apparatus according to claim 1, wherein the notification process is not executed when the difference between the two-wire voltage and the two-wire voltage is smaller than the threshold value. a wire voltage application unit that applies voltage to the first wire and the second wire;
further comprising a current measuring unit that measures the current flowing through the first grid and the current flowing through the second grid,
The control unit includes:
a first application process of applying a voltage to the first wire and the second wire by the wire voltage application unit before executing the image forming process;
a second measurement process of measuring a first grid current flowing to the first grid and a second grid current flowing to the second grid by the current measurement unit when the first application process is executed; further run
In the detection process, it is detected that the first scorotron charger is new and that the second scorotron charger is an old product, and the first grid current measured in the second measurement process and the second grid current are detected. If the difference from the second grid current is equal to or greater than the threshold, execute the notification process,
In the detection process, it is detected that the first scorotron charger is new and that the second scorotron charger is an old product, and the first grid current measured in the second measurement process and the second grid current are detected. 2. The image forming apparatus according to claim 1, wherein the notification process is not executed when the difference from the second grid current is smaller than the threshold value. a cover that covers the first photoreceptor cartridge and the second photoreceptor cartridge;
further comprising a cover sensor that detects opening and closing of the cover,
The control unit includes:
2. The method of claim 1, further comprising performing a first determination process of determining that the wire has been cleaned if the cover sensor detects that the cover is closed after executing the notification process. The image forming apparatus described above. a wire voltage application unit that applies voltage to the first wire and the second wire;
further comprising a voltage measuring unit that measures the voltage applied to the first wire and the second wire,
The control unit includes:
After executing the notification process and before executing the image forming process, a second application process of applying a voltage to the first wire and the second wire by the wire voltage application unit;
A third measurement in which the voltage measurement unit measures a first starting voltage that is a voltage at which the first wire starts corona discharge, and a second starting voltage that is a voltage at which the second wire starts corona discharge. processing and
Image forming according to claim 1, further comprising performing a second determination process of determining whether or not cleaning of the wire has been performed based on the first start voltage and the second start voltage. Device. The information that prompts cleaning of the wire notified in the notification process is information that prompts cleaning of the first wire and the second wire, or information that prompts cleaning of the first scorotron charger and the second scorotron charger. 2. The image forming apparatus according to claim 1, wherein the information is for prompting cleaning of a wire of a scorotron charger that is detected to be present.

Images