# US 2013/0155737 A1 · Switching mode power supply usable in an image forming apparatus, and image forming apparatus and method of supplying power by using the same > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2013/0155737 A1 - Document ID: US20130155737A1 - Status: Published application - Kind: A1 - Application number: 13/713,559 - Filed: 2012-12-13 - Published: 2013-06-20 - Earliest claimed: 2011-12-15 - Assignees: Samsung Electronics Co., Ltd. - Inventors: An-sik JEONG - Web page: https://patentgrep.com/patent/US20130155737A1 ## CPC - H02M 7/04: by static converters - H02M 3/33507: {with automatic control of the output voltage or current, e.g. flyback converters (H02M3/33561, H02M3/33569 take precedence)} - H02M 1/0032: {Control circuits allowing low power mode operation, e.g. in standby mode} - Y02B 70/10: Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes - 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) - Y02B: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS ## Abstract A switching mode power supply and a method of supplying power by using the same. The switching mode power supply includes a converting unit to convert an alternating current (AC) voltage input to the switching mode power supply to at least one direct current (DC) voltage by using at least one transformer, and a voltage controller to control a voltage level of an output voltage to be output to a system controller of the image forming apparatus from among the at least one DC voltage, where the system controller controls operations of the image forming apparatus. The voltage controller includes a switching unit to switch the voltage level of the output voltage from a first voltage level to a second voltage level when the image forming apparatus enters a power saving mode, where the second voltage level is lower than the first voltage level. ## Claims ### Claim 1 A switching mode power supply of an image forming apparatus, the switching mode power supply comprising: a converting unit to convert an alternating current (AC) voltage input to the switching mode power supply to at least one direct current (DC) voltage by using at least one transformer; and a voltage controller to control a voltage level of an output voltage to be output to a system controller of the image forming apparatus from among the at least one DC voltage, where the system controller controls operations of the image forming apparatus, wherein the voltage controller comprises a switching unit to switch the voltage level of the output voltage from a first voltage level to a second voltage level when the image forming apparatus enters a power saving mode, where the second voltage level is lower than the first voltage level. ### Claim 2 (depends on 1) The switching mode power supply of claim 1, wherein the switching unit switches the voltage level of the output voltage, based on a control signal received from the system controller. ### Claim 3 (depends on 1) The switching mode power supply of claim 1, wherein the voltage controller is connected to a secondary coil of the at least one transformer so as to control the voltage level of the output voltage. ### Claim 4 (depends on 1) The switching mode power supply of claim 1, the voltage controller further comprises a voltage stabilizer including a voltage regulator connected in parallel to an output terminal to output the output voltage, and at least one resistor connected to a reference voltage terminal of the voltage regulator, wherein the switching unit is connected to the reference voltage terminal of the voltage regulator, and wherein the switching unit comprises a diode that is turned on or off based on a voltage of a control signal received from the system controller; and at least one resistor connected in series to the diode. ### Claim 5 (depends on 4) The switching mode power supply of claim 4, wherein the switching unit is turned on to switch the voltage level of the output voltage to the second voltage level, based on the control signal received from the system controller, when the image forming apparatus enters the power saving mode. ### Claim 6 (depends on 4) The switching mode power supply of claim 4, wherein the second voltage level is determined according to a resistance value of the at least one resistor. ### Claim 7 (depends on 6) The switching mode power supply of claim 6, wherein the at least one resistor is a variable resistor, and wherein the system controller determines the resistance value of the variable resistor as a resistance value to minimize power consumption in the power saving mode from among resistance values of the variable resistor. ### Claim 8 (depends on 4) The switching mode power supply of claim 4, wherein the second voltage level is determined according to a voltage level of the voltage of the control signal, and wherein the voltage level of the control signal is a voltage value converted by a digital-analog converter of the system controller. ### Claim 9 (depends on 8) The switching mode power supply of claim 8, wherein the system controller determines the voltage level of the control signal as a voltage value to minimize power consumption in the power saving mode from among voltage values converted by the digital-analog converter. ### Claim 10 (depends on 1) The switching mode power supply of claim 1, the voltage controller further comprises a voltage stabilizer including a voltage regulator connected in parallel to an output terminal to output the output voltage, and at least one resistor connected to a reference voltage terminal of the voltage regulator, and wherein the switching unit comprises a transistor that is turned on or off based on a control signal received from the system controller. ### Claim 11 (depends on 10) The switching mode power supply of claim 10, wherein the switching unit is connected in parallel to the at least one resistor connected between the reference voltage terminal of the voltage regulator and the output terminal. ### Claim 12 (depends on 11) The switching mode power supply of claim 11, wherein the switching unit is turned on to switch the voltage level of the output voltage to the second voltage level, according to a control signal received from the system controller, when the image forming apparatus enters the power saving mode. ### Claim 13 (depends on 10) The switching mode power supply of claim 10, wherein the switching unit is connected in parallel to at least one series resistor connected between the reference voltage terminal of the voltage regulator and ground. ### Claim 14 (depends on 13) The switching mode power supply of claim 13, wherein the switching unit is turned off to switch the voltage level of the output voltage to the second voltage level, based on a control signal received from the system controller, when the image forming apparatus enters the power saving mode. ### Claim 15 (depends on 1) The switching mode power supply of claim 1, wherein the converting unit converts the AC voltage input to the switching mode power supply to a DC voltage and then outputs the DC voltage as the output voltage, and the output voltage is output to the image forming apparatus, including the system controller. ### Claim 16 (depends on 1) The switching mode power supply of claim 1, wherein the converting unit converts the AC voltage input to the switching mode power supply to a first output voltage and a second output voltage, wherein the voltage controller controls a voltage level of the first output voltage, and switches the voltage level of the first output voltage from the first voltage level to the second voltage level when the image forming apparatus enters the power saving mode, and the first output voltage and the second output voltage are output to the system controller and an image forming unit of the image forming apparatus, respectively. ### Claim 17 An image forming apparatus which includes a switching mode power supply, the image forming apparatus comprising: a system controller to control operations of the image forming apparatus, and to output a control signal to control a switching operation of the switching mode power supply according to whether the image forming apparatus is in an operating mode or a power saving mode; and the switching mode power supply to convert an alternating current (AC) voltage input thereto to at least one direct current (DC) voltage by using at least one transformer, to switch a voltage level of an output voltage, which is output to the system controller from among the at least one DC voltage, to a first voltage level or a second voltage level according to the control signal, and then to output the switched output voltage to the system controller, where the second voltage level is lower than the first voltage level. ### Claim 18 (depends on 17) The image forming apparatus of claim 17, wherein, when the image forming apparatus enters the power saving mode, the switching mode power supply switches the voltage level of the output voltage from the first voltage level to the second voltage level. ### Claim 19 (depends on 17) The image forming apparatus of claim 17, wherein the switching mode power supply comprises: a voltage stabilizer to stabilize the output voltage by using a voltage regulator connected in parallel to an output terminal to output the output voltage, and at least one resistor connected between a reference voltage terminal of the voltage regulator and the output terminal; and a switching unit including a transistor connected in parallel to the at least one resistor, wherein, when the image forming apparatus enters the power saving mode, the switching unit turns on the transistor to switch the voltage level of the output voltage to the second voltage level, based on the control signal. ### Claim 20 (depends on 17) The image forming apparatus of claim 17, wherein the switching mode power supply comprises: a voltage stabilizer to stabilize the output voltage by using a voltage regulator connected in parallel to an output terminal to output the output voltage, and at least one resistor connected between a reference voltage terminal of the voltage regulator and ground; and a switching unit including a transistor connected in parallel to the at least one resistor, wherein, when the image forming apparatus enters the power saving mode, the switching unit turns off the transistor to switch the voltage level of the output voltage to the second voltage level, based on the control signal. ### Claim 21 (depends on 17) The image forming apparatus of claim 17, wherein the switching mode power supply comprises: a voltage stabilizer to stabilize the output voltage by using a voltage regulator connected in parallel to an output terminal to output the output voltage, and at least one resistor connected between a reference voltage terminal of the voltage regulator and the output terminal; and a switching unit comprising a diode connected to the reference voltage terminal of the voltage regulator; and a resistor connected in series to the diode, wherein the switching unit is connected to the reference voltage terminal of the voltage regulator, and wherein the switching unit turns on the diode to switch the voltage level of the output voltage to the second voltage level, based on the control signal, when the image forming apparatus enters the power saving mode. ### Claim 22 A method of supplying power to an image forming apparatus by using a switching mode power supply, the method comprising: converting an alternating current (AC) voltage input to the switching mode power supply into at least one direct current (DC) voltage by using at least one transformer; receiving a control signal to control a switching operation of the switching mode power supply according to whether the image forming apparatus is in an operating mode or a power saving mode, from a system controller that controls operations of the image forming apparatus; switching a voltage level of an output voltage, which is output to the system controller from among the at least one DC voltage, to a first voltage level or a second voltage level, based on the control signal, where the second voltage level is lower than the first voltage level; and outputting the switched output voltage to the system controller. ### Claim 23 (depends on 22) The method of claim 22, wherein the switching of the voltage level comprises switching the voltage level of the output voltage from the first voltage level to the second voltage level when the image forming apparatus enters the power saving mode. ### Claim 24 (depends on 22) The method of claim 22, further comprising stabilizing the output voltage by using a voltage regulator and at least one series resistor, where the voltage regulator is connected in parallel to an output terminal to output the output voltage and the at least one series resistor is connected between a reference voltage terminal of the voltage regulator and the output terminal, and wherein the switching of the voltage level comprises switching the voltage level of the output voltage by using a transistor connected in parallel to the at least one series resistor, and turning on the transistor to switch the voltage level of the output voltage to the second voltage level, based on the control signal, when the image forming apparatus enters the power saving mode. ### Claim 25 (depends on 22) The method of claim 22, further comprising stabilizing the output voltage by using a voltage regulator and at least one series resistor, where the voltage regulator is connected in parallel to an output terminal to output the output voltage and the at least one series resistor is connected between a reference voltage terminal of the voltage regulator and ground, and wherein the switching of the voltage level comprises switching the voltage level of the output voltage by using a transistor connected in parallel to the at least one series resistor, and turning off the transistor to switch the voltage level of the output voltage to the second voltage level, based on the control signal, when the image forming apparatus enters the power saving mode. ### Claim 26 (depends on 22) The method of claim 22, further comprising stabilizing the output voltage by using a voltage regulator and at least one series resistor, where the voltage regulator is connected in parallel to an output terminal to output the output voltage and the at least one series resistor is connected between a reference voltage terminal of the voltage regulator and ground, and wherein the switching of the voltage level comprises switching the voltage level of the output voltage by using a diode connected to the reference voltage terminal of the voltage regulator; and a resistor connected in series to the diode, and turning off the diode to switch the voltage level of the output voltage to the second voltage level, based on the control signal, when the image forming apparatus enters the power saving mode. ### Claim 27 A computer readable recording medium having embodied thereon a computer program to execute a method of supplying power to an image forming apparatus by using a switching mode power supply, wherein the method comprises: converting an alternating current (AC) voltage input to the switching mode power supply into at least one direct current (DC) voltage by using at least one transformer; receiving a control signal to control a switching operation of the switching mode power supply according to whether the image forming apparatus is in an operating mode or a power saving mode, from a system controller that controls operations of the image forming apparatus; switching a voltage level of an output voltage, which is output to the system controller from among the at least one DC voltage, to a first voltage level or a second voltage level, based on the control signal, where the second voltage level is lower than the first voltage level; and outputting the switched output voltage to the system controller.