Image forming apparatus

Abstract

To provide an image forming apparatus that can stabilize a voltage output from an LED controller board to an LED head.SOLUTION: An LED controller board (110) outputs a voltage based on a first voltage (V1) to an LED head (18), the first voltage (V1) input to a third voltage terminal (DT3). A fourth voltage terminal (DT4) and an LED controller (112) are electrically connected with each other. A voltage based on a second voltage (V2) input to the fourth voltage terminal (DT4) is input to the LED controller (112).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] This disclosure relates to an image forming apparatus.

Background Art

[0002] Patent Document 1 describes an image forming apparatus including an LED head that exposes the surface of a photosensitive drum, an LED control board having a sub-ASIC that controls the light emission of the LED head, and a main board having a main-ASIC that controls the exposure timing of the photosensitive drum.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the image forming apparatus of Patent Document 1, when the main board outputs a voltage to the LED head via the LED control board, the voltage output from the main board to the LED control board is divided into two systems: the voltage output to the LED head on the LED control board and the voltage for driving the sub-ASIC of the LED control board.

[0005] However, when exposing the surface of the photosensitive drum with the LED head, a large current flowing through the LED head may be required to increase the amount of light emitted by the LED head. When the voltage input from the main board is divided into two systems on the LED control board, the voltage output to the LED head may become unstable.

[0006] An object of this disclosure is to realize an image forming apparatus capable of stabilizing the voltage output from the LED controller board to the LED head.

Means for Solving the Problems

[0007] To solve the above problems, an image forming apparatus according to one aspect of the present disclosure includes: a photosensitive drum; an LED head that emits LED light and exposes the surface of the photosensitive drum; a main controller; a voltage output circuit that outputs a first voltage and a second voltage, respectively; a first voltage terminal that outputs the first voltage output by the voltage output circuit to the outside; a second voltage terminal that outputs the second voltage output by the voltage output circuit to the outside; a main controller board electrically connected to the main controller and inputting and outputting control signals; a third voltage terminal electrically connected to the first voltage terminal via a first wiring; and a second wiring The LED controller board includes a fourth voltage terminal electrically connected via a wire, a second input / output terminal electrically connected to the first input / output terminal via control wiring, and an LED controller that transmits and receives the control signals to and from the main controller via the second input / output terminal and controls the emission of light from the LED head. The LED controller board outputs a voltage to the LED head based on the first voltage input to the third voltage terminal, the fourth voltage terminal and the LED controller are electrically connected, and the LED controller receives a voltage based on the second voltage input to the fourth voltage terminal.

[0008] According to the first embodiment, the main controller board has voltage output circuits that output a first voltage and a second voltage, respectively. The voltage based on the first voltage is input to the LED head from the main controller board via the first wiring and the LED controller board. The voltage based on the second voltage is input to the LED controller from the main controller board via the second wiring. As a result, in the image forming apparatus, the voltage is divided into two systems on the main controller board, one for the LED controller and the other for the LED head. Therefore, even if the voltage required to drive the LED head increases, the voltage output by the LED controller board to the LED head can be kept stable.

[0009] The second embodiment is an image forming apparatus according to the first embodiment, further comprising a power supply board having a power supply circuit that converts an AC voltage input from an external commercial power supply into a first DC voltage, wherein the voltage output circuit has a first voltage conversion circuit that converts the first voltage into a second voltage and outputs the second voltage to the second voltage terminal.

[0010] According to the second embodiment, an AC voltage from an external commercial power supply is converted to a first voltage by a power supply circuit on the power supply board. The first voltage conversion circuit in the voltage output circuit converts the first voltage output from the power supply circuit to a second voltage. As a result, the image forming apparatus can convert the AC voltage input from an external commercial power supply to a DC voltage by a power supply circuit on the power supply board. Then, on the main controller board, the DC voltage is divided into two systems, one of which is further converted to another DC voltage, and these voltages can be input to the LED controller and the LED head, respectively.

[0011] The third embodiment is an image forming apparatus according to the first or second embodiment, wherein the LED controller board further includes a second voltage conversion circuit electrically connected between the third voltage terminal and the LED head, the second voltage conversion circuit converts the first voltage to a third voltage and outputs the third voltage to the LED head, the second voltage conversion circuit outputs a detection signal to the LED controller which becomes a Low signal when the third voltage is less than a predetermined voltage required to drive the LED head, the main controller obtains information from the LED controller via the control wiring indicating whether the detection signal is a Low signal, and detects whether the third voltage is less than the predetermined voltage.

[0012] According to the third embodiment, when a third voltage below a predetermined voltage is output to the LED head, the detection signal output by the second voltage conversion circuit to the LED controller becomes a Low signal. The main controller obtains information from the LED controller indicating whether or not the detection signal is a Low signal. As a result, the main controller can detect whether the third voltage output to the LED head is below a predetermined voltage by obtaining information about the detection signal output by the second voltage conversion circuit to the LED controller, and can detect an error in which the third voltage is not being output to the LED head due to wiring defects such as a blown fuse.

[0013] The fourth embodiment is an image forming apparatus according to the third embodiment, wherein the LED controller board has a third voltage conversion circuit that converts the second voltage input to the fourth voltage terminal into a fourth voltage and outputs the fourth voltage to the LED controller.

[0014] According to the fourth embodiment, the third voltage conversion circuit converts the second voltage to the fourth voltage and outputs it to the LED controller. This supplies the LED controller with the voltage necessary to drive the LED controller.

[0015] The fifth embodiment is an image forming apparatus according to the third or fourth embodiment, wherein the LED controller has a common terminal to which both the detection signal and the control signal are input, and the detection signal is input from the second voltage conversion circuit at times when image forming is not performed, and the control signal used during image forming is input from the main controller at times when image forming is performed.

[0016] According to the fifth embodiment, a detection signal is input to the LED controller from the second voltage conversion circuit at a time when image formation is not being performed. A control signal is input to the LED controller from the main controller at a time when image formation is being performed. Since the detection signal and the control signal are input to the LED controller at different times, the number of input terminals for the LED controller can be reduced by making the terminals to which the detection signal and the control signal are input common.

[0017] The sixth embodiment is an image forming apparatus according to the fifth embodiment, wherein the control signal output by the main controller to the LED controller at the timing of image forming is a signal instructing the start of light emission control of the LED head.

[0018] According to the sixth embodiment, the common terminal of the LED controller receives a detection signal from the second voltage conversion circuit when image formation is not being performed, and a control signal, which is a signal instructing the start of light emission control of the LED head, is received from the main controller when image formation is being performed. As a result, in the image forming apparatus, the number of terminals connected to the LED controller can be reduced by making the terminal for inputting the detection signal to the LED controller and the terminal for inputting the control signal to the LED controller common.

[0019] The seventh embodiment is an image forming apparatus according to any one of the third to sixth embodiments, wherein the second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, the detection signal of the second voltage conversion circuit outputs a High signal when the third voltage is equal to or greater than a predetermined voltage required to drive the LED head, the LED controller board has a pull-up resistor, one end of which is electrically connected to the control wiring and the other end of which is electrically connected to the detection signal output terminal, the main controller has a switch element, one end of which is grounded and the other end of which is electrically connected to the first input / output terminal, and the LED controller, when the detection signal is a High signal, receives a Low signal when the switch element is on, receives a High signal when the switch element is off, and receives a Low signal when the detection signal is a Low signal, regardless of whether the switch element is on or off.

[0020] According to the seventh embodiment, by electrically connecting one end of the pull-up resistor to the control wiring and electrically connecting the other end of the pull-up resistor to the detection signal output terminal, the High signal output from the detection signal output terminal functions as the reference potential of the pull-up resistor. When the switch element is off, if a Low signal is detected from the LED controller, the detection signal is a Low signal. The main controller obtains information from the LED controller indicating whether or not the detection signal is a Low signal. As a result, the main controller can detect whether the third voltage output to the LED head is below a predetermined voltage and can detect an error where the third voltage is not output to the LED head due to wiring defects such as a blown fuse.

[0021] The eighth embodiment is an image forming apparatus according to any one of the third to sixth embodiments, wherein the second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, the detection signal output terminal of the second voltage conversion circuit is high impedance when the third voltage is equal to or greater than the predetermined voltage required to drive the LED head, the LED controller board has a pull-up resistor with one end electrically connected to the control wiring and the other end electrically connected to a reference potential, the detection signal output terminal is electrically connected to the control wiring, the main controller has a switch element with one end grounded and the other end electrically connected to the first input / output terminal, the LED controller has a switch element with one end grounded and the other end electrically connected to the first input / output terminal, when the detection signal output terminal is high impedance, a Low signal is input when the switch element is on, a High signal is input when the switch element is off, and when the detection signal output terminal is outputting a Low signal, a Low signal is input regardless of whether the switch element is on or off.

[0022] According to the eighth embodiment, one end of the pull-up resistor is connected to the control wiring, and the other end of the pull-up resistor is electrically connected to a reference potential. When the switch element is off, if a Low signal is detected from the LED controller, the detected signal is a Low signal. The main controller obtains information from the LED controller indicating whether or not the detected signal is a Low signal. As a result, the main controller can detect whether the third voltage output to the LED head is below a predetermined voltage and can detect an error where the third voltage is not output to the LED head due to wiring defects such as a blown fuse.

[0023] The ninth aspect is an image forming apparatus according to any one of the third to sixth aspects, wherein the second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, and the detection signal output terminal of the second voltage conversion circuit is a high impedance when the third voltage exceeds a predetermined voltage required for driving the LED head. The detection signal output terminal is electrically connected to the control wiring. The main controller has a first switch element and a second switch element. One end of the first switch element is connected to a reference potential. The other end of the first switch element and one end of the second switch element are electrically connected in series and are also electrically connected to the control wiring. The other end of the second switch element is grounded. When the first switch element is on, the second switch element is off. When the first switch element is off, the second switch element is on. The LED controller inputs a Low signal when the detection signal output terminal outputs a Low signal and inputs a High signal when the detection signal output terminal is a high impedance when the first switch element is on and the second switch element is off. This is the characteristic.

[0024] According to the ninth aspect, one end of the first switch element is electrically connected to a reference potential. When the first switch element is on and the second switch element is off, if a Low signal is detected from the LED controller, the detection signal is a Low signal. The main controller acquires information indicating whether the detection signal from the LED controller is a Low signal. Thereby, the main controller can detect whether the third voltage output to the LED head is less than a predetermined voltage, and can detect an error that the third voltage is not output to the LED head due to a wiring defect such as a blown fuse.

[0025] The tenth aspect is an image forming apparatus according to any one of the third to ninth aspects, wherein the LED controller has a register that stores information indicating whether the detection signal is a Low signal, and the main controller acquires the information stored in the register via the control wiring.

[0026] According to the tenth aspect, the LED controller stores information indicating whether the detection signal is a Low signal in a register, and the main controller acquires the information stored in the register via the control wiring. Thereby, the main controller can detect whether the third voltage output to the LED head is less than a predetermined voltage, and can detect an error that the third voltage is not output to the LED head due to a wiring defect such as a blown fuse.

Effects of the Invention

[0027] According to one aspect of the present disclosure, the image forming apparatus can stabilize the voltage output from the LED controller board to the LED head.

Brief Description of the Drawings

[0028] [Figure 1] It is a schematic side sectional view showing the internal configuration of the image forming apparatus according to Embodiment 1 of the present disclosure. [Figure 2] It is a functional configuration diagram showing the electrical configuration of the image forming apparatus according to Embodiment 1 of the present disclosure. [Figure 3] It is a flowchart of the power supply detection control process to the LED head of the image forming apparatus according to Embodiment 1 of the present disclosure. [Figure 4] It is a functional configuration diagram showing the electrical configuration of the image forming apparatus according to a modification of Embodiment 1 of the present disclosure. [Figure 5] It is an electrical wiring diagram of the image forming apparatus according to Embodiment 2 of the present disclosure. [Figure 6] It is an electrical wiring diagram of the image forming apparatus according to Embodiment 3 of the present disclosure. [Figure 7] It is an electrical wiring diagram of the image forming apparatus according to a modification of Embodiment 3 of the present disclosure.

Modes for Carrying Out the Invention

[0029] 〔Embodiment 1〕 Hereinafter, Embodiment 1 of the present disclosure will be described in detail.

[0030] <Overall configuration of image forming apparatus 1> Figure 1 is a schematic side cross-sectional view showing the internal configuration of the image forming apparatus 1. In the following description, when referring to the image forming apparatus 1 as "top," "bottom," "front," "rear," "right," and "left," these correspond to the directions indicated by the arrows in Figure 1 and other figures as appropriate.

[0031] As shown in Figure 1, the image forming apparatus 1 is an LED color printer that forms color images using four developer colors consisting of yellow (Y), magenta (M), cyan (C), and black (K).

[0032] In the following explanation, when components are distinguished by color, the letters "Y" for yellow, "M" for magenta, "C" for cyan, and "K" for black will be added to the end of the component's code. When components are not distinguished by color, the aforementioned "Y," "M," "C," and "K" will be omitted. Note that in Figures 1, 2, and 4, components are distinguished by color, and the aforementioned "Y," "M," "C," and "K" are added to the end of the component's code.

[0033] However, the image forming apparatus 1 is not limited to an LED color printer; for example, it may be a laser color printer, a facsimile machine, or a so-called multifunction device equipped with printer and reading functions.

[0034] As shown in Figure 1, the image forming apparatus 1 includes, within its main body housing 2, a paper feeding unit 10 for supplying sheets 3, an image forming unit 20 for forming images on the fed sheets 3, a paper discharge unit 30 for discharging the sheets 3 on which images have been formed, a main controller board 100 for controlling each unit when forming images, an LED controller board 110 for controlling each LED head 18Y to 18K, and a power supply board 120 for supplying DC voltage to each unit.

[0035] An upper cover 2A is provided on the upper part of the main housing 2, which opens and closes an opening 36 in the main housing 2, and is rotatable vertically with a pivot shaft 37 located at the rear. The upper surface of the upper cover 2A is a paper output tray 34 for accumulating the sheets 3 discharged from the main housing 2, and the lower surface is provided with multiple holding members 39 for holding the exposure unit 17. A shield plate 35 is also provided inside the upper cover 2A.

[0036] The shielding plate 35 shields against noise such as electromagnetic waves generated by the LED controller board 110. As shown in Figure 1, the shielding plate 35 consists of an upper shielding plate 35B that faces the upper surface of the LED controller board 110 and a lower shielding plate 35A that faces the lower surface of the LED controller board 110.

[0037] The paper feeding unit 10 is located in the lower part of the main body housing 2 and mainly comprises a paper feeding tray 4 that is detachably attached to the main body housing 2, and a paper supply mechanism 40 that transports the sheet 3 from the paper feeding tray 4 to the image forming unit 20. The paper supply mechanism 40 consists of a pickup roller 5, a separation roller 71, and a transport roller 72.

[0038] A pickup roller 5 is provided above the front end of the paper feed tray 4. As the pickup roller 5 rotates, the sheet 3 stacked at the top of the paper feed tray 4 is fed to the separation roller 71.

[0039] The sheets 3 are separated one by one between the separation roller 71 and a separation pad (not shown), and then conveyed toward the conveyor roller 72. After that, the position of the front end of the sheets 3 is restricted by the registration roller 6, which is in a stopped state, and then conveyed toward the transfer unit 11 via the conveyor path.

[0040] Furthermore, a paper feed sensor 9, a pre-register sensor 8, and a post-register sensor 7 are provided on the transport path, capable of detecting the passage of the sheet 3. The paper feed sensor 9 is located downstream of the pickup roller 5 and the separation roller 71 in the transport direction of the sheet 3. The pre-register sensor 8 is located downstream of the paper feed sensor 9 and the transport roller 72, and upstream of the register roller 6, in the transport direction of the sheet 3. The post-register sensor 7 is located downstream of the register roller 6, and upstream of the photosensitive drum 28Y, in the transport direction of the sheet 3.

[0041] The image forming unit 20 mainly consists of four exposure units 17Y to 17K, four process units 19Y to 19K, a transfer unit 11, and a fixing unit 31. The exposure units 17Y to 17K are positioned above the photosensitive drums 28Y to 28K and mainly consist of LED heads 18Y to 18K and backplates 38Y to 38K, with the LED heads 18Y to 18K positioned opposite the photosensitive drums 28Y to 28K.

[0042] The transfer unit 11 is located between the paper feeding section 10 and each process section 19Y to 19K, and mainly comprises a belt support roller 12A, a belt drive roller 12B, a belt 13, and transfer rollers 14Y to 14K.

[0043] The transfer unit 11 has a configuration in which an annular belt 13 is stretched between a belt support roller 12A located at the front and a belt drive roller 12B located at the rear. Inside the belt 13, there are photosensitive drums 28Y to 28K corresponding to each of the four process sections 19Y to 19K, and transfer rollers 14Y to 14K are provided at positions opposite each other across the belt 13.

[0044] The belt-driven roller 12B is connected to a process motor (not shown) located inside the main housing 2, via a gear mechanism (not shown), when the transfer unit 11 is mounted inside the main housing 2. The belt-driven roller 12B is rotated by the power of the process motor, causing the belt 13 to circulate in the clockwise direction shown, thereby conveying the sheet 3 on the upper surface of the belt 13 backward.

[0045] Above the transfer unit 11, exposure units 17Y to 17K, corresponding to each of the four process units 19Y to 19K, are arranged in a front-to-back direction. The exposure units 17Y to 17K are supported on the lower surface of the upper cover 2A, and each exposure unit 17Y to 17K is equipped with an LED head 18Y to 18K at its lower end, which has multiple LEDs arranged in a row. The exposure unit 17 is controlled to emit light based on the image data to be formed, and exposure is performed by irradiating the surface of the photosensitive drum 28 with LED light from the LED head 18 line by line, that is, by scanning the photosensitive drum 28 line by line.

[0046] Each of the process units 19Y to 19K comprises a cartridge frame 21Y to 21K, a developing cartridge 22Y to 22K that is detachably attached to each of the cartridge frames 21Y to 21K, a photosensitive drum 28Y to 28K, and a charger 29Y to 29K. When the upper cover 2A is opened, the exposure unit 17 retracts upward together with the upper cover 2A, and the process units 19 become individually detachable from the main housing 2.

[0047] Each of the developing cartridges 22Y to 22K is equipped with a developing chamber 23Y to 23K for containing the developing agent of each color, and on the underside of each is a supply roller 24Y to 24K, a developing roller 25Y to 25K, and a layer thickness regulating blade 26Y to 26K.

[0048] The developer released from the developer storage chamber 23 is supplied onto the developing roller 25 by the rotation of the supply roller 24, and is positively triboelectrically charged between the supply roller 24 and the developing roller 25. Furthermore, as the developing roller 25 rotates, the developer supplied onto the developing roller 25 penetrates between the layer thickness regulating blade 26 and the developing roller 25, where it is further sufficiently triboelectrically charged and supported on the developing roller 25 as a thin layer of a certain thickness.

[0049] At the bottom of the cartridge frame 21 are a photosensitive drum 28 whose surface is covered with, for example, a positively charged photosensitive layer, and a charger 29. During image formation, the photosensitive drum 28 is rotated, and as a result, the surface of the photosensitive drum 28 is uniformly positively charged by the charger 29. Then, the positively charged portion is exposed by scanning by the exposure unit 17, and an electrostatic latent image is formed on the surface of the photosensitive drum 28.

[0050] Next, the positively charged developer supported on the developing roller 25 is supplied to the electrostatic latent image on the surface of the photosensitive drum 28, thereby making the electrostatic latent image on the photosensitive drum 28 visible. Subsequently, the developer image supported on the surface of the photosensitive drum 28 is sequentially transferred onto the sheet 3 by a negative polarity transfer voltage applied to the transfer roller 14 as the sheet 3 passes through the nip position between the photosensitive drum 28 and the transfer roller 14. The sheet 3 with the transferred developer image is then transported to the fixing unit 31 equipped with a heater 31A.

[0051] The fixing unit 31 includes a heating roller 33 with a heater 31A and a pressure roller 32 that presses the sheet 3 toward the heating roller 33, thereby heat-fixing the developer image transferred onto the sheet 3 to the paper surface. After that, the sheet 3 that has been heat-fixed by the fixing unit 31 is transported upward and accumulated in the output tray 34 on the upper surface of the upper cover 2A.

[0052] The power supply board 120 is electrically connected to the main controller board 100 via the power supply line PL1. The main controller board 100 is electrically connected to the LED controller board 110 via the first wiring L1. The main controller board 100 is also electrically connected to the LED controller board 110 via the second wiring L2. The LED controller board 110 is electrically connected to each LED head 18Y~18K via the power supply line PL9.

[0053] <Electrical configuration of image forming apparatus 1> Figure 2 is a functional configuration diagram showing the electrical configuration of an image forming apparatus according to Embodiment 1 of the present disclosure. The main controller board 100 includes a first voltage terminal DT1, a second voltage terminal DT2, a first fuse H1, a second fuse H2, a voltage output circuit 102, a main controller 101, and a first input / output terminal T1. The voltage output circuit 102 has a first voltage conversion circuit 103.

[0054] The LED controller board 110 includes a third voltage terminal DT3, a fourth voltage terminal DT4, a second voltage conversion circuit 111, a third voltage conversion circuit 115, an LED controller 112, and a second input / output terminal T2. The second voltage conversion circuit 111 has a detection signal output terminal To that outputs a detection signal Vd, which will be described later. The LED controller 112 further has a register 113. The register 113 stores information 114, which will be described later.

[0055] The power supply board 120 includes a power supply circuit 121.

[0056] The power supply circuit 121 receives the AC voltage from an external commercial power supply and generates a first voltage V1. The power supply circuit 121 outputs the first voltage V1 to the voltage output circuit 102.

[0057] The first voltage conversion circuit 103 converts the first voltage V1 to the second voltage V2.

[0058] The voltage output circuit 102 outputs a first voltage V1 and a second voltage V2, respectively. The voltage output circuit 102 outputs the first voltage V1 to the first fuse H1. The voltage output circuit 102 outputs the second voltage V2 to the second fuse H2.

[0059] The first fuse H1 will break if the current based on the first voltage V1 exceeds a predetermined value. This configuration prevents overcurrents caused by circuit failures or short circuits from flowing through each LED head 18Y~18K.

[0060] The second fuse H2 will break if the current based on the second voltage exceeds a predetermined value. This configuration prevents overcurrents caused by circuit failures or short circuits from flowing to the LED controller 112.

[0061] The main controller 101 sends and receives a control signal Vs to the LED controller 112 via the control wiring CL. For example, the control signal Vs is a signal that instructs the start of light emission control of the LED head 18 at the timing when image formation is performed.

[0062] The second voltage conversion circuit 111 converts the first voltage V1 to the third voltage V3. If the third voltage V3 is less than a predetermined voltage, the second voltage conversion circuit 111 outputs a detection signal Vd, which is a Low signal, from the detection signal output terminal To.

[0063] The detection signal Vd is input to the LED controller 112. The detection signal Vd is stored in the register 113 of the LED controller 112 as information 114 indicating whether or not the detection signal Vd is a Low signal.

[0064] The second voltage conversion circuit 111 outputs the third voltage V3 to each LED head 18Y~18K.

[0065] The third voltage, V3, drives each LED head from 18Y to 18K.

[0066] The third voltage conversion circuit 115 converts the second voltage V2 to the fourth voltage V4. The third voltage conversion circuit 115 outputs the fourth voltage V4 to the LED controller 112.

[0067] The fourth voltage V4 drives the LED controller 112.

[0068] The LED controller 112 sends and receives signals to control the illumination of each LED head 18Y to 18K. The LED controller 112 sends information 114, which indicates whether the detection signal Vd stored in register 113 is a Low signal, to the main controller 101. As a result, the main controller 101 obtains the information 114 indicating whether the detection signal Vd is a Low signal.

[0069] The power supply circuit 121 is electrically connected to the voltage output circuit 102 via the power supply line PL1. The voltage output circuit 102 is electrically connected to the first fuse H1 via the power supply line PL2. Also, the voltage output circuit 102 is electrically connected to the second fuse H2 via the power supply line PL4. The first fuse H1 is electrically connected to the first voltage terminal DT1 via the power supply line PL3. The first voltage terminal DT1 is electrically connected to the third voltage terminal DT3 via the first wiring L1. The third voltage terminal DT3 is electrically connected to the second voltage conversion circuit 111 via the power supply line PL6. The second voltage conversion circuit 111 is electrically connected to each of the LED heads 18Y to 18K via the power supply line PL9. The second fuse H2 is connected to the second voltage terminal DT2 via the power supply line PL5. The second voltage terminal DT2 is electrically connected to the fourth voltage terminal DT4 via the second wiring L2. The fourth voltage terminal DT4 is electrically connected to the third voltage conversion circuit 115 via the power supply line PL7. The third voltage conversion circuit 115 is electrically connected to the LED controller 112 via the power supply line PL8. The main controller 101 is electrically connected to the first input / output terminal T1 via the signal line SL1. The first input / output terminal T1 is electrically connected to the second input / output terminal T2 via the control wiring CL. The second input / output terminal T2 is electrically connected to the LED controller 112 via the signal line SL2. The LED controller 112 electrically connects between each of the LED heads 18Y to 18K via the flat cables 140Y to 1 (error in original, should be 140K). The detection signal output terminal To is electrically connected to the LED controller 112 via the detection signal line Ld.

[0070] <Power supply detection process for the LED head 18> It should be noted that there seems to be an error in the original text where it says "flat cables 140Y to 1" instead of "140K" in the relevant description. This has been corrected in the translation as much as possible while maintaining the integrity of the original text.Figure 3 is a flowchart of the power supply detection process to the LED heads 18 of the image forming apparatus 1 according to Embodiment 1 of this disclosure. If the first wiring L1 is faulty due to a break in the first fuse H1 or a poor connection in the first wiring, power will not be supplied to each LED head 18Y to 18K. On the other hand, if power is supplied to the second wiring L2, the LED controller 112 will be driven. Therefore, at the timing of image formation, the LED controller 112 may be driven, but the LED heads 18 may not be driven, and an image may not be formed on the sheet 3.

[0071] The main controller 101 detects that the LED head 18 is not receiving power because the third voltage V3 is below a predetermined voltage. The main controller 101 then notifies the user that the LED head 18 is not receiving power and controls the LED controller 112 to stop supplying power.

[0072] Power supply detection control to the LED head 18 is performed at times when image formation is not being carried out. For example, when the power to the image forming apparatus 1 is turned ON, but image formation has not yet been performed.

[0073] First, the power supply detection control for the LED head 18 is initiated.

[0074] Step S101: Turn on the power to the image forming apparatus 1. Then proceed to step S102.

[0075] Step S102: The main controller 101 obtains information 114 stored in register 113 of the LED controller 112 from the LED controller 112.

[0076] Step S103: The main controller 101 determines whether information 114 indicates that the detected signal Vd is a Low signal. If information 114 indicates that the detected signal Vd is a Low signal (Yes in step S103), the process proceeds to step S104. If information 114 does not indicate a Low signal (No in step S103), the process ends.

[0077] Step S104: The main controller 101 determines that the third voltage V3 is below a predetermined voltage required to drive the LED head 18 and notifies the user of an abnormal power supply to the LED head 18. Next, the process proceeds to step S105. For example, the notification of the abnormal power supply to the LED head 18 to the user is made by displaying an error on a display unit (not shown) of the image forming apparatus 1.

[0078] Step S105: The main controller 101 stops supplying power to the LED controller 112. Specifically, the main controller 101 stops driving the third voltage conversion circuit 115, which generates the fourth voltage V4 output to the LED controller 112. Alternatively, the main controller 101 stops driving the first voltage conversion circuit 103, which generates the second voltage V2 output to the third voltage conversion circuit 115. This terminates the process.

[0079] <Effects and Actions> The main controller board 100 has a voltage output circuit 102 that outputs a first voltage V1 and a second voltage V2, respectively. The voltage based on the first voltage V1 is input to the LED head 18 from the main controller board 100 via the first wiring L1 and the LED controller board 110. The voltage based on the second voltage V2 is input to the LED controller 112 from the main controller board 100 via the second wiring L2.

[0080] As a result, in the image forming apparatus 1, the voltage is divided into two systems on the main controller board 100: one for the LED controller 112 and the other for the LED head 18. Even if the voltage required to drive the LED head 18 increases, the voltage output by the LED controller board 110 to the LED head 18 can be kept stable.

[0081] The AC voltage from the external commercial power supply (AC) is converted to a first voltage V1 by the power supply circuit 121 on the power supply board 120. The first voltage conversion circuit 103 of the voltage output circuit 102 converts the first voltage V1 output from the power supply circuit 121 to a second voltage V2.

[0082] As a result, the image forming apparatus 1 can convert the AC voltage input from the external commercial power supply AC into a DC voltage using the power supply circuit 121 on the power supply board 120. Then, on the main controller board 100, the DC voltage is divided into two systems, one of which is further converted into another DC voltage, and these voltages can be input to the LED controller 112 and the LED head 18, respectively.

[0083] When a third voltage V3 below a predetermined voltage is output to the LED head 18, the detection signal Vd output by the second voltage conversion circuit 111 to the LED controller 112 becomes a Low signal. The main controller 101 obtains information 114 from the LED controller 112 indicating whether or not the detection signal Vd is a Low signal. As a result, the main controller 101 obtains the information 114 of the detection signal Vd output by the second voltage conversion circuit 111 to the LED controller 112. The main controller 101 can detect whether the third voltage V3 output to the LED head 18 is below a predetermined voltage and can detect an error in which the third voltage V3 is not output to the LED head 18 due to wiring problems such as a blown fuse.

[0084] The third voltage conversion circuit 115 converts the second voltage V2 to the fourth voltage V4 and outputs it to the LED controller 112. This supplies the LED controller 112 with the voltage necessary to drive it.

[0085] The LED controller 112 stores information 114 in register 113 indicating whether the detection signal Vd is a Low signal or not, and the main controller 101 retrieves the information 114 stored in register 113 indicating whether the detection signal Vd is a Low signal or not. As a result, the main controller 101 can detect whether the third voltage V3 output to the LED head 18 is below a predetermined voltage and detect an error where the third voltage V3 is not output to the LED head 18 due to wiring problems such as a blown fuse.

[0086] [Modified example of Embodiment 1] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0087] Figure 4 is a functional configuration diagram showing the electrical configuration of an image forming apparatus 1A according to a modified embodiment 1 of the present disclosure. The LED controller 112 has a common terminal Tc to which both the detection signal Vd and the control signal Vs are input. The detection signal output terminal To, which outputs the detection signal Vd, is electrically connected to the common terminal Tc via the detection signal line LtA. The main controller 101 receives the control signal Vs to the common terminal Tc via the signal line SL1, the first input / output terminal T1, the control wiring CL, the second input / output terminal T2, and the signal line SL2.

[0088] The common terminal Tc of the LED controller 112 receives a detection signal Vd from the second voltage conversion circuit 111 when image formation is not being performed. The common terminal Tc of the LED controller 112 receives a control signal Vs used during image formation from the main controller 101 when image formation is being performed.

[0089] The LED controller 112 acquires a detection signal Vd from the common terminal Tc when image formation is not being performed, and a control signal Vs when image formation is being performed.

[0090] This allows the number of terminals connected to the LED controller 112 to be reduced by making the terminal for inputting the detection signal Vd to the LED controller 112 and the terminal for inputting the control signal Vs to the LED controller 112 common.

[0091] The control signal Vs that the main controller 101 outputs to the LED controller 112 at the timing of image formation is a signal that instructs the start of light emission control of the LED head 18.

[0092] The LED controller 112 acquires a detection signal Vd from the second voltage conversion circuit 111 when it is not performing image formation. The LED controller 112 acquires a control signal Vs from the main controller 101, which is a signal instructing the start of light emission control of the LED head 18, when it is performing image formation.

[0093] As a result, in the image forming apparatus 1A, the number of terminals input to the LED controller can be reduced by making the terminal for inputting the detection signal Vd to the LED controller 112 and the terminal for inputting the control signal Vs to the LED controller 112 common.

[0094] [Embodiment 2] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0095] Figure 5 is an electrical wiring diagram of an image forming apparatus 1B according to Embodiment 2 of the present disclosure. The detection signal Vd of the second voltage conversion circuit 111 outputs a High signal when the third voltage V3 is equal to or greater than a predetermined voltage required to drive the LED head 18. The detection signal Vd of the second voltage conversion circuit 111 outputs a Low signal when the third voltage V3 is less than a predetermined voltage required to drive the LED head 18.

[0096] The LED controller board 110 has a pull-up resistor Rp1, one end of which is electrically connected to the control wiring CL, and the other end of which is electrically connected to the detection signal output terminal To via the detection signal line LdB. The main controller 101 has a switch element SW, one end of which is grounded, and the other end of which is electrically connected to the first input / output terminal T1 via the signal line SL1.

[0097] When the detection signal Vd is a High signal, the LED controller 112 receives a Low signal if the switch element SW is ON, and a High signal if the switch element SW is OFF. On the other hand, when the detection signal Vd is a Low signal, a Low signal is received regardless of whether the switch element SW is ON or OFF.

[0098] By electrically connecting one end of the pull-up resistor Rp1 to the control wiring CL and the other end of the pull-up resistor Rp1 to the detection signal output terminal To, the High signal output from the detection signal output terminal To functions as the reference potential of the pull-up resistor Rp1. When the switch element SW is off, if a Low signal is detected from the LED controller 112, the detection signal Vd is a Low signal. The main controller 101 obtains information 114 from the LED controller 112 indicating whether or not the detection signal Vd is a Low signal. As a result, the main controller 101 can detect whether the third voltage V3 output to the LED head 18 is less than a predetermined voltage, and can detect an error where the third voltage V3 is not output to the LED head 18 due to wiring problems such as a blown fuse.

[0099] [Embodiment 3] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0100] Figure 6 is an electrical wiring diagram of an image forming apparatus 1C according to Embodiment 3 of the present disclosure. The detection signal output terminal To of the second voltage conversion circuit 111 is high impedance when the third voltage V3 is equal to or greater than a predetermined voltage required to drive the LED head 18. The detection signal output terminal To of the second voltage conversion circuit 111 outputs a low signal when the third voltage V3 is less than a predetermined voltage required to drive the LED head 18.

[0101] When the detection signal output terminal To is described as having high impedance, it means that the impedance between the detection signal output terminal To and ground (GND) is extremely high. When the detection signal output terminal To has high impedance, only a very weak current flows through the detection signal line LdC, and the detection signal Vd is no longer output from the detection signal output terminal To.

[0102] A Low signal is output from the detection signal output terminal To, meaning that the detection signal output terminal To is connected to ground (GND). In this state, the potential of the detection signal output terminal To is at a Low level.

[0103] The LED controller board 110 has a pull-up resistor Rp2. One end of the pull-up resistor Rp2 is electrically connected to the control wiring CL, and the other end of the pull-up resistor Rp2 is electrically connected to the reference potential Vcc. The detection signal output terminal To is electrically connected to the control wiring CL via the detection signal line LdC. The main controller 101 has a switch element SW, one end of which is grounded and the other end of which is electrically connected to the first input / output terminal T1 via the signal line SL1.

[0104] When the detection signal output terminal To of the LED controller 112 is high impedance, a Low signal is input when the switch element SW is on, and a High signal is input when the switch element SW is off. On the other hand, when the detection signal output terminal To of the LED controller 112 is outputting a Low signal, a Low signal is input regardless of whether the switch element SW is on or off.

[0105] One end of the pull-up resistor Rp2 is connected to the control wiring CL, and the other end of the pull-up resistor Rp2 is electrically connected to the reference potential Vcc. When the switch element SW is off, if a Low signal is detected from the LED controller 112, the detected signal Vd is a Low signal. The main controller 101 obtains information 114 from the LED controller 112 indicating whether or not the detected signal Vd is a Low signal. As a result, the main controller 101 can detect whether the third voltage V3 output to the LED head 18 is less than a predetermined voltage, and can detect an error where the third voltage V3 is not output to the LED head 18 due to wiring problems such as a blown fuse.

[0106] [Modified version of Embodiment 3] Other embodiments of this disclosure are described below. For the sake of clarity, components having the same function as those described in the above embodiments are denoted by the same reference numerals, and their descriptions are not repeated.

[0107] Figure 7 is an electrical wiring diagram of an image forming apparatus 1D according to a modified example of Embodiment 3 of the present disclosure. The detection signal output terminal To of the second voltage conversion circuit 111 is high impedance when the third voltage V3 is equal to or greater than a predetermined voltage required to drive the LED head 18. The detection signal output terminal To of the second voltage conversion circuit 111 outputs a low signal when the third voltage V3 is less than a predetermined voltage required to drive the LED head 18.

[0108] The detection signal output terminal To is electrically connected to the control wiring CL via the detection signal line LdC. The main controller 101 has a first switch element SW1 and a second switch element SW2. One end of the first switch element SW1 is connected to a reference potential Vcc, and the other end of the first switch element SW1 and one end of the second switch element SW2 are electrically connected in series, as well as being electrically connected to the control wiring CL. The other end of the second switch element SW2 is grounded.

[0109] When the first switch element SW1 is ON, the second switch element SW2 is OFF, and when the first switch element SW1 is OFF, the second switch element SW2 is ON.

[0110] When the first switch element SW1 is ON and the second switch element SW2 is OFF, the LED controller 112 receives a Low signal if the detection signal output terminal To is outputting a Low signal, and receives a High signal if the detection signal output terminal To is high impedance.

[0111] One end of the first switch element SW1 is electrically connected to a reference potential Vcc. When the first switch element SW1 is ON and the second switch element SW2 is OFF, if a Low signal is detected from the LED controller 112, then the detected signal Vd is a Low signal. The main controller 101 obtains information 114 from the LED controller 112 indicating whether or not the detected signal Vd is a Low signal. As a result, the main controller 101 can detect whether the third voltage V3 output to the LED head 18 is below a predetermined voltage and detect an error where the third voltage V3 is not output to the LED head 18 due to wiring problems such as a blown fuse.

[0112] Furthermore, when the first switch element SW1 is off and the second switch element SW2 is on, the LED controller 112 receives a low signal even if the detection signal output terminal To outputs a low signal or has high impedance. When the control signal Vs is a low signal and no image formation is performed, the state in which the first switch element SW1 is off and the second switch element SW2 is on is never adopted.

[0113] This disclosure is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of this disclosure. [Explanation of symbols]

[0114] 1, 1A, 1B, 1C, 1D image forming device 18 LED Head 28 Photosensitive drum 100 Main Controller Board 101 Main Controller 102 Voltage Output Circuit 103 First Voltage Conversion Circuit 110 LED Controller Board 111 Second Voltage Conversion Circuit 112 LED Controller 115 Third Voltage Conversion Circuit 120 Power Supply Board 121 Power supply circuit DT1 First voltage terminal DT2 Second voltage terminal DT3 Third voltage terminal DT4 4th voltage terminal T1 1st input / output terminal T2 2nd input / output terminal

Claims

1. Photosensitive drum and An LED head that emits LED light and exposes the surface of the photosensitive drum, A main controller board having a main controller, a voltage output circuit that outputs a first voltage and a second voltage respectively, a first voltage terminal that outputs the first voltage output by the voltage output circuit to the outside, a second voltage terminal that outputs the second voltage output by the voltage output circuit to the outside, and a first input / output terminal that is electrically connected to the main controller and inputs and outputs control signals, An LED controller board having: a third voltage terminal electrically connected to the first voltage terminal via a first wiring; a fourth voltage terminal electrically connected to the second voltage terminal via a second wiring; a second input / output terminal electrically connected to the first input / output terminal via control wiring; and an LED controller that transmits and receives the control signals to and from the main controller via the second input / output terminal and controls the illumination of the LED head; Equipped with, The aforementioned LED controller board is A voltage based on the first voltage input to the third voltage terminal is output to the LED head. The fourth voltage terminal and the LED controller are electrically connected. The LED controller receives a voltage based on the second voltage input to the fourth voltage terminal. An image forming apparatus characterized by the following features.

2. The power supply board further comprises a power supply circuit that converts an AC voltage input from an external commercial power supply into the first DC voltage, The aforementioned voltage output circuit is The circuit includes a first voltage conversion circuit that converts the first voltage to the second voltage and outputs the second voltage to the second voltage terminal. The image forming apparatus according to feature 1.

3. Photosensitive drum and An LED head that emits LED light and exposes the surface of the photosensitive drum, A main controller board having a voltage output circuit that outputs the first voltage and the second voltage respectively, having a first voltage conversion circuit that converts the first voltage to a second voltage and outputs the second voltage to a second voltage terminal, a main controller, a first voltage terminal that outputs the first voltage output by the voltage output circuit to the outside, a second voltage terminal that outputs the second voltage output by the voltage output circuit to the outside, and a first input / output terminal that is electrically connected to the main controller and inputs and outputs control signals, An LED controller board having: a third voltage terminal electrically connected to the first voltage terminal via a first wiring; a fourth voltage terminal electrically connected to the second voltage terminal via a second wiring; a second input / output terminal electrically connected to the first input / output terminal via control wiring; a second voltage conversion circuit electrically connected between the third voltage terminal and the LED head; and an LED controller that transmits and receives the control signals to and from the main controller via the second input / output terminal and controls the illumination of the LED head. A power supply board having a power supply circuit that converts an AC voltage input from an external commercial power supply into the first voltage which is a DC voltage, Equipped with, The aforementioned LED controller board is A voltage based on the first voltage input to the third voltage terminal is output to the LED head. The fourth voltage terminal and the LED controller are electrically connected. The LED controller receives a voltage based on the second voltage input to the fourth voltage terminal. The second voltage conversion circuit described above is: The first voltage is converted to a third voltage, and the third voltage is output to the LED head. If the third voltage is less than a predetermined voltage required to drive the LED head, a detection signal which is a Low signal is output to the LED controller. The aforementioned main controller Information indicating whether the detection signal is a Low signal is obtained from the LED controller via the control wiring, and it is detected whether the third voltage is less than the predetermined voltage. An image forming apparatus characterized by the following features.

4. The aforementioned LED controller board is The device has a third voltage conversion circuit that converts the second voltage input to the fourth voltage terminal into a fourth voltage and outputs the fourth voltage to the LED controller. The image forming apparatus according to feature 3.

5. The LED controller has a common terminal to which both the detection signal and the control signal are input. The common terminal of the LED controller is At a time when image formation is not being performed, the detection signal is input from the second voltage conversion circuit. At the timing of image formation, the control signals used during image formation are input from the main controller. The image forming apparatus according to feature 3 or 4.

6. The aforementioned main controller At the timing of image formation, the control signal output to the LED controller is a signal instructing the start of light emission control of the LED head. The image forming apparatus according to feature 5.

7. The second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, The detection signal of the second voltage conversion circuit outputs a High signal if the third voltage is equal to or greater than a predetermined voltage required to drive the LED head. The aforementioned LED controller board is A pull-up resistor has one end electrically connected to the control wiring and the other end electrically connected to the detection signal output terminal. The aforementioned main controller A switch element having one end grounded and the other end electrically connected to the first input / output terminal, The aforementioned LED controller If the detection signal is a High signal, When the aforementioned switch element is ON, a Low signal is input. When the aforementioned switch element is off, a High signal is input. If the detection signal is a Low signal, Regardless of whether the aforementioned switch element is on or off, a Low signal is input. The image forming apparatus according to any one of claims 3 to 6.

8. The second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, The detection signal output terminal of the second voltage conversion circuit is high impedance when the third voltage is equal to or greater than the predetermined voltage required to drive the LED head. The aforementioned LED controller board is It has a pull-up resistor, one end of which is electrically connected to the control wiring and the other end of which is electrically connected to a reference potential. The detection signal output terminal is electrically connected to the control wiring. The aforementioned main controller A switch element having one end grounded and the other end electrically connected to the first input / output terminal, The aforementioned LED controller If the detection signal output terminal is of high impedance, When the aforementioned switch element is ON, a Low signal is input. When the aforementioned switch element is off, a High signal is input. When the detection signal output terminal outputs a Low signal, Regardless of whether the aforementioned switch element is on or off, a Low signal is input. The image forming apparatus according to any one of claims 3 to 6.

9. The second voltage conversion circuit has a detection signal output terminal that outputs the detection signal, The detection signal output terminal of the second voltage conversion circuit is high impedance when the third voltage exceeds a predetermined voltage required to drive the LED head. The detection signal output terminal is electrically connected to the control wiring. The aforementioned main controller It has a first switch element and a second switch element, One end of the first switching element is connected to a reference potential, The other end of the first switch element and one end of the second switch element are electrically connected in series, and are also electrically connected to the control wiring. The other end of the second switching element is grounded. When the first switch element is ON, the second switch element is OFF. When the first switch element is off, the second switch element is on. The aforementioned LED controller When the first switch element is on and the second switch element is off, If the aforementioned detection signal output terminal outputs a Low signal, a Low signal is input. If the detection signal output terminal is high impedance, a High signal is input. The image forming apparatus according to any one of claims 3 to 6.

10. The LED controller has a register that stores information indicating whether the detection signal is a Low signal or not. The main controller acquires the information stored in the register via the control wiring. The image forming apparatus according to any one of claims 3 to 9.

Images