# US 11,112,720 B2 · Technique for transmitting signal indicating abnormality in image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 11,112,720 B2 - Document ID: US11112720B2 - Status: Granted - Kind: B2 - Application number: 16/928,272 - Filed: 2020-07-14 - Published: 2021-01-28 - Granted: 2021-09-07 - Earliest claimed: 2019-07-25 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Satoshi Ogawara - Web page: https://patentgrep.com/patent/US11112720B2 ## CPC - G03G 15/0258: {provided with means for the maintenance of the charging apparatus, e.g. cleaning devices, ozone removing devices G03G15/0225, G03G15/0291 takes precedence} - G03G 15/5004: {Power supply control, e.g. power-saving mode, automatic power turn-off} - G03G 15/0291: {corona discharge devices, e.g. wires, pointed electrodes, means for cleaning the corona discharge device} - G03G 15/55: {Self-diagnostics; Malfunction or lifetime display} - G03G 15/80: {Details relating to power supplies, circuits boards, electrical connections} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming unit forms an image on a sheet. A first generation circuit generates, regarding a member involved in image formation in the image forming unit, a first signal relating to a first abnormality. A second generation circuit generates, regarding the member, a second signal that relates to a second abnormality different from the first abnormality, and whose feature in a time axis direction or a frequency axis direction is different from that of the first signal. A control circuit has a single port to which the first signal and the second signal are to be input. The control circuit identifies between the first signal and the second signal based on a feature of a signal input to the port. ## Claims ### Claim 1 An image forming apparatus comprising: an image forming unit that forms an image on a sheet; a first generation circuit that generates, regarding a member involved in image formation in the image forming unit, a first signal relating to a first abnormality; a second generation circuit that generates, regarding the member, a second signal that relates to a second abnormality different from the first abnormality, and whose feature in a time axis direction or a frequency axis direction is different from that of the first signal; and a control circuit having a single port to which the first signal and the second signal are to be input, wherein the control circuit is configured to identify between the first signal and the second signal based on a feature of a signal input to the port. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein a period of the first signal is different from a period of the second signal. ### Claim 3 (depends on 2) The image forming apparatus according to claim 2, wherein the control circuit includes: a counter that counts one of a falling edge and a rising edge of a signal input to the port; and an identification circuit that distinguishes between the first signal and the second signal based on a count value of the counter. ### Claim 4 (depends on 1) The image forming apparatus according to claim 1, wherein the first signal and the second signal are each a pulse signal, and wherein a number of pulses per unit time with respect to the first signal is different from a number of pulses per unit time with respect to the second signal. ### Claim 5 (depends on 4) The image forming apparatus according to claim 4, wherein the control circuit includes: a counter that counts a number of pulses of a signal input to the port; and an identification circuit that distinguishes between the first signal and the second signal based on a count value of the counter. ### Claim 6 (depends on 1) The image forming apparatus according to claim 1, further comprising: an AC power supply circuit that generates an AC voltage according to a driving signal output from the control circuit, and supplies the AC voltage to a load, wherein the first generation circuit includes: an AC detection circuit that detects a current supplied to the load; a signal generation circuit that, upon an overcurrent being detected by the AC detection circuit, generates the first signal; and a first restricting circuit that, upon an overcurrent being detected by the AC detection circuit, restricts the operation of the AC power supply circuit. ### Claim 7 (depends on 6) The image forming apparatus according to claim 6, wherein the first restricting circuit is a circuit that allows and cuts off the supply of the driving signal from the control circuit to the AC power supply circuit. ### Claim 8 (depends on 1) The image forming apparatus according to claim 1, further comprising: a DC power supply circuit that generates a DC voltage according to a driving signal output from the control circuit, and supplies the DC voltage to a load, wherein the second generation circuit includes: a DC detection circuit that detects a DC voltage that is supplied from the DC power supply circuit to the load; a signal generation circuit that, upon an overvoltage being detected by the DC detection circuit, generates the second signal; and a second restricting circuit that, upon an overvoltage being detected by the DC detection circuit, restricts the operation of the DC power supply circuit. ### Claim 9 (depends on 8) The image forming apparatus according to claim 8, wherein the second restricting circuit is a circuit that allows and cuts off the supply of the driving signal from the control circuit to the DC power supply circuit. ### Claim 10 (depends on 8) The image forming apparatus according to claim 8, wherein the second restricting circuit is a circuit that cuts off the supply of the driving signal from the control circuit to the DC power supply circuit. ### Claim 11 (depends on 10) The image forming apparatus according to claim 10, wherein the second restricting circuit includes a latch circuit that, upon an overvoltage being detected by the DC detection circuit, continues cutting off the supply of the driving signal from the control circuit to the DC power supply circuit. ### Claim 12 (depends on 1) The image forming apparatus according to claim 1, wherein a member involved in image formation is a charger for keeping a charge amount of toner that is carried by a photoreceptor at a charge amount in a target range. ### Claim 13 (depends on 12) The image forming apparatus according to claim 12, wherein the first signal is a signal indicating that a first maintenance is needed, and the first maintenance is cleaning of the charger. ### Claim 14 (depends on 12) The image forming apparatus according to claim 12, wherein the first signal is a signal indicating that a leakage current has occurred regarding a wire that is provided in the charger and charges the photoreceptor with corona discharge. ### Claim 15 (depends on 12) The image forming apparatus according to claim 12, wherein the second signal is a signal indicating that a second maintenance is needed, and the second maintenance is repair or replacement of the charger. ### Claim 16 (depends on 15) The image forming apparatus according to claim 15, wherein the second signal is a signal indicating that a wire that is provided in the charger and charges the photoreceptor with corona discharge is broken. ### Claim 17 (depends on 1) The image forming apparatus according to claim 1, wherein the first generation circuit includes a first time constant circuit that determines a period of the first signal. ### Claim 18 (depends on 1) The image forming apparatus according to claim 1, wherein the second generation circuit includes a second time constant circuit that determines a period of the second signal. ### Claim 19 (depends on 1) The image forming apparatus according to claim 1, further comprising an output unit that, upon the control circuit identifying the first signal, outputs a first message corresponding to the first signal, and upon the control circuit identifying the second signal, outputs a second message corresponding to the second signal. ### Claim 20 An image forming apparatus comprising: a charging unit that charges an image carrier; an image forming unit that forms a toner image on the image carrier charged by the charging unit; a power supply unit that supplies a charging voltage in which an AC voltage is superimposed on a DC voltage to the charging unit; a first generation circuit that detects a first abnormality regarding the DC voltage, in the power supply unit, and upon detecting the first abnormality, generates a first signal having a first pattern; a second generation circuit that detects a second abnormality regarding the AC voltage, in the power supply unit, and upon detecting the second abnormality, generates a second signal having a second pattern that is different from the first pattern; and a control circuit having a single port to which the first signal and the second signal are to be input, wherein the control circuit is configured to distinguish between the first signal and the second signal based on a pattern of a signal input to the port.