# US 2014/0192574 A1 · Technique for reducing power consumed by electric equipment > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0192574 A1 - Document ID: US20140192574A1 - Status: Published application - Kind: A1 - Application number: 14/146,455 - Filed: 2014-01-02 - Published: 2014-07-10 - Earliest claimed: 2013-01-10 - Assignees: Canon Kabushiki Kaisha - Applicants: Canon Kabushiki Kaisha - Inventors: Tetsuya Nozaki - Web page: https://patentgrep.com/patent/US20140192574A1 ## CPC - G03G 15/5004: {Power supply control, e.g. power-saving mode, automatic power turn-off} - G03G 15/80: {Details relating to power supplies, circuits boards, electrical connections} - H02M 1/0006: {Arrangements for supplying an adequate voltage to the control circuit of converters} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P) ## Abstract When an image forming apparatus shifts to a power saving mode, a controller unit further reduces power consumption by switching AC current on/off every predetermined amount of time. When AC current input from a commercial AC power supply is turned off, a DC voltage generating circuit normally can no longer supply a DC voltage, rendering the controller unit unable to operate. Accordingly, the controller unit operates using a charge accumulated in a smoothing capacitor while the AC current is not being supplied. An AC cutting circuit is switched on before a both-end voltage at the smoothing capacitor drops below a lower limit of operation voltage of the DC voltage generating circuit, and the smoothing capacitor is recharged. ## Claims ### Claim 1 Electric equipment having a normal power supply mode and a power saving mode that consumes less power than the normal power supply mode, the equipment comprising: an AC cutting circuit, connected serially to a power supply line through which AC current is input, configured to turn the supply of the AC current on and off; a rectifying and smoothing circuit configured to rectify the AC current and smoothes the AC current using a capacitor; a DC voltage generating circuit, connected to the rectifying and smoothing circuit, configured to generate a DC voltage; and a controller, operating under the DC voltage generated by the DC voltage generating circuit, configured to cause the AC cutting circuit to turn the supply of the AC current off when the electric equipment shifts to the power saving mode, and then cause the AC cutting circuit to turn the supply of the AC current on every predetermined amount of time in order to charge the capacitor. ### Claim 2 (depends on 1) The electric equipment according to claim 1, wherein the DC voltage generating circuit is further configured to generate the DC voltage based on a charge of the capacitor after the AC cutting circuit has been caused to turn the supply of the AC current off. ### Claim 3 (depends on 1) The electric equipment according to claim 1, wherein the predetermined amount of time is an amount of time shorter than an amount of time from a time when the AC cutting circuit is caused to turn the supply of the AC current off until a time when a voltage in the capacitor drops below a lower limit of operation voltage of the controller. ### Claim 4 (depends on 1) The electric equipment according to claim 1, wherein the predetermined amount of time is set in accordance with the AC voltage input to the electric equipment. ### Claim 5 (depends on 1) The electric equipment according to claim 1, wherein the AC cutting circuit includes a photo triac. ### Claim 6 (depends on 5) The electric equipment according to claim 5, wherein the AC cutting circuit includes a circuit in which an electromagnetic relay and a photo triac are connected in parallel; and the AC cutting circuit is configured so that the electromagnetic relay turns off during the power saving mode and the photo triac turns on when the AC current is supplied in order to charge the capacitor. ### Claim 7 (depends on 1) The electric equipment according to claim 1, further comprising: a line filter, wherein the AC cutting circuit cuts AC current to the line filter during the power saving mode. ### Claim 8 An image forming apparatus having a normal power supply mode and a power saving mode that consumes less power than the normal power supply mode, the apparatus comprising: an AC cutting circuit, connected serially to a power supply line through which AC current is input, configured to turn the supply of the AC current on and off; a rectifying and smoothing circuit configured to rectify the AC current and smoothes the AC current using a capacitor; a DC voltage generating circuit, connected to the rectifying and smoothing circuit, configured to generate a DC voltage; and a controller, operating under the DC voltage generated by the DC voltage generating circuit, configured to cause the AC cutting circuit to turn the supply of the AC current off when the electric equipment shifts to the power saving mode, and then cause the AC cutting circuit to turn the supply of the AC current on every predetermined amount of time in order to charge the capacitor. ### Claim 9 An image forming apparatus comprising: a switch serially connected to one of two power supply lines through which AC current is input; a rectifying circuit configured to rectify the AC current and smoothes the AC current using a capacitor; a DC voltage generating circuit configured to generate a DC voltage based on an output of the rectifying circuit; and a controller, operating under the DC voltage generated by the DC voltage generating circuit, configured to repeatedly turn the switch on and off when the image forming apparatus shifts from an image forming mode in which the image forming apparatus can form images to a power saving mode that consumes less power than the image forming mode, wherein the DC voltage generating circuit is further configure to generate the DC voltage using a voltage supplied by the capacitor when the controller sets the switch to off, and the controller is configured to set the switch on before a both-end voltage at the capacitor drops below a lower limit of operation voltage of the DC voltage generating circuit. ### Claim 10 (depends on 9) The image forming apparatus according to claim 9, further comprising: a timer configured to measure an amount of time from a time the switch is set to off, wherein the timer is caused to measure a predetermined amount of time that is shorter than an amount of time from a time when the switch is set to off until a time when a time at which the both-end voltage at the capacitor drops below a lower limit of operation voltage of the controller, and charging of the capacitor is caused to resume before the both-end voltage at the capacitor drops below the lower limit of operation voltage of the controller by setting the switch to on when the timer finishes measuring the predetermined amount of time. ### Claim 11 (depends on 9) The image forming apparatus according to claim 9, further comprising: a first switch contact provided serially in the other of the two power supply lines through which the AC current is input; and a second switch contact provided serially in the one of the two power supply lines through which the AC current is input, wherein the switch is provided in parallel relative to the second switch contact; and the second switch contact is switched on along with the first switch contact, and is switched off by the controller when the image forming apparatus shifts to the power saving mode. ### Claim 12 (depends on 9) The image forming apparatus according to claim 9, wherein the switch is a photo triac. ### Claim 13 (depends on 9) The image forming apparatus according to claim 9, further comprising: a first switch contact provided serially in the other of the two power supply lines through which the AC current is input; a second switch contact provided serially in the one of the two power supply lines through which the AC current is input; and a third switch contact provided serially relative to the second switch contact, wherein the switch is provided serially relative to the second switch contact and in parallel relative to the third switch contact; and the third switch contact is switched on along with the first switch contact and the second switch contact, and is switched off by the controller when the image forming apparatus shifts to the power saving mode. ### Claim 14 (depends on 9) The image forming apparatus according to claim 9, further comprising: a first switch contact provided serially in the other of the two power supply lines through which the AC current is input; a second switch contact provided serially in the one of the two power supply lines through which the AC current is input; and a bistable relay provided serially relative to the second switch contact, wherein the switch is provided serially relative to the second switch contact and in parallel relative to the bistable relay; and the bistable relay is switched off by the controller when the image forming apparatus shifts to the power saving mode and is switched on by the controller when the first switch contact and the second switch contact are switched off. ### Claim 15 (depends on 9) The image forming apparatus according to claim 9, further comprising: a line filter provided for the two power supply lines through which the AC current is input; and a discharge resistance configured to discharge a charge accumulated in the line filter when the supply of the AC current is cut. ### Claim 16 (depends on 9) The image forming apparatus according to claim 9, further comprising: a cutting circuit, controlled by the controller, configured to supply and cuts power between the DC voltage generating circuit and a constituent element, wherein when the image forming apparatus shifts to the power saving mode, the controller cuts power from the DC voltage generating circuit to the constituent element by switching the cutting circuit from on to off.