# US 2008/0187347 A1 · Fuser, image forming apparatus, and method to control the apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0187347 A1 - Document ID: US20080187347A1 - Status: Published application - Kind: A1 - Application number: 12/023,270 - Filed: 2008-01-31 - Published: 2008-08-07 - Earliest claimed: 2007-02-01 - Assignees: Samsung Electronics Co., Ltd. - Inventors: Hyun Soo SONG - Web page: https://patentgrep.com/patent/US20080187347A1 ## CPC - G03G 15/2039: {with means for controlling the fixing temperature} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A fuser, an image forming apparatus, and a method to control the apparatus includes a power supply unit to supply power to a plurality of heat sources provided in the fuser, and is controlled to gradually increase and change in a stepwise manner an amount of current supplied alternately to the plurality of heat sources, thereby preventing an inrush current and uneven fusing of images. ## Claims ### Claim 1 A fuser, comprising: a heating member having a plurality of heat sources; and a controller to control power supplied to each of the plurality of heat sources such that an amount of a current supplied to each of the plurality of heat sources is increased gradually and is changed in a stepwise manner. ### Claim 2 (depends on 1) The fuser according to claim 1, wherein the controller changes a chopping rate of power to change the amount of the current. ### Claim 3 (depends on 2) The fuser according to claim 2, wherein the chopping rate includes a plurality of chopping rates and the controller uses the plurality of chopping rates when changing the amount of the current alternately supplied to the plurality of heat sources in the stepwise manner. ### Claim 4 An image forming apparatus, comprising: a fuser including a plurality of heat sources; a power supply unit to supply power to the plurality of heat sources; and a controller to control the power supply unit such that an amount of a current supplied to each of the plurality of heat sources is increased gradually and is changed in a stepwise manner from a change start time to a change end time. ### Claim 5 (depends on 4) The apparatus according to claim 4, wherein the controller changes a chopping rate of the power to change the amount of the current. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein the controller alternately increases the chopping rate for the plurality of heat sources. ### Claim 7 (depends on 5) The apparatus according to claim 5, further comprising: a storage unit to store a plurality of chopping rates for each of the plurality of heat sources, wherein the controller changes the chopping rate of the power to a desired one of the plurality of chopping rates. ### Claim 8 (depends on 5) The apparatus according to claim 5, wherein the power supply unit includes a switch connected to a power source to supply the power, wherein the controller controls the switch according to the chopping rate on a basis of a half cycle of the power. ### Claim 9 (depends on 4) The apparatus according to claim 4, wherein the power supply unit comprises: a zero crossing detector to detect zero crossing of the power. ### Claim 10 A method to control an image forming apparatus, the method comprising: determining whether there is a need to change an amount of a current supplied to each of a plurality of heat sources provided in a fuser; and gradually increasing and changing, in a stepwise manner, the amount of the current supplied to each of the plurality of heat sources if there is a need to change the amount of the current. ### Claim 11 (depends on 10) The method according to claim 10, wherein changing the amount of the current comprises: changing a chopping rate of power. ### Claim 12 (depends on 11) The method according to claim 11, wherein changing the amount of the current further comprises: detecting zero crossing of the power; and changing the chopping rate on a basis of a half cycle of the power according to the detected zero crossing. ### Claim 13 (depends on 11) The method according to claim 11, wherein changing the amount of the current further comprises: alternately increasing the chopping rate for the plurality of heat sources. ### Claim 14 A fuser unit usable with an image forming apparatus, the fuser unit comprising: a first and second heating source to fuse an image on a printing medium; and a controlling unit to apply current to the first heat source to reach a first predetermined level, and to apply current to the second heat source to reach a second predetermined level prior to the first heat source reaching the first predetermined level. ### Claim 15 (depends on 14) The fuser unit of claim 14, wherein an amount of the current applied to the first and second heat sources, respectively, is based on predetermined chopping rates, a number of heating sources to be activated, and a size of the printing medium. ### Claim 16 A fuser unit usable with an image forming apparatus, the fuser unit comprising: a first and second heating source to fuse an image on a printing medium; and a controlling unit to increase predetermined chopping rates of a first and second heat source at substantially different times during a same interval. ### Claim 17 (depends on 16) The fuser unit of claim 16, further comprising: a power unit to receive AC power and to supply power to the first and second heating sources. ### Claim 18 (depends on 17) The fuser unit of claim 17, wherein the same interval corresponds to one half cycle of the AC power. ### Claim 19 A fusing method of a fusing unit, the method comprising: fusing an image on a printing medium by a first and second heating source; applying current to the first heat source to reach a first predetermined level; and applying current to the second heat source to reach a second predetermined level prior to the first heat source reaching the first predetermined level. ### Claim 20 A computer-readable recording medium having embodied thereon a computer program to execute a method, wherein the method comprises: fusing an image on a printing medium by a first and second heating source; applying current to the first heat source to reach a first predetermined level; and applying current to the second heat source to reach a second predetermined level prior to the first heat source reaching the first predetermined level.