# US 2018/0321613 A1 · Image forming apparatus and developer replacement method of 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 2018/0321613 A1 - Document ID: US20180321613A1 - Status: Published application - Kind: A1 - Application number: 16/019,600 - Filed: 2018-06-27 - Published: 2018-11-08 - Earliest claimed: 2016-11-02 - Assignees: Kabushiki Kaisha Toshiba; Toshiba Tec Kabushiki Kaisha - Applicants: Kabushiki Kaisha Toshiba; Toshiba Tec Kabushiki Kaisha - Inventors: Koji Imamiya; Kei Onishi - Web page: https://patentgrep.com/patent/US20180321613A1 ## CPC - G03G 15/0849: {Detection or control means for the developer concentration} - G03G 15/0877: {Arrangements for metering and dispensing developer from a developer cartridge into the development unit} - G03G 15/556: {for toner consumption, e.g. pixel counting, toner coverage detection or toner density measurement} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus of an exemplary embodiment includes a temperature sensor, a developing unit, a supply unit, and a control unit. The temperature sensor detects a temperature. The developing unit supplies developer to an image carrier and performs development. The supply unit contains developer and supplies the contained developer to the developing unit. The control unit executes developer replacement processing including discharging the developer from the developing unit and supplying the developer contained in the supply unit to the developing unit based on a first ratio which a ratio of a developer supply time during which the supply unit performs supply of the developer for the developing unit and a drive time during which the developing unit is driven and a threshold value obtained based on a detected temperature of a temperature sensor. ## Claims ### Claim 1 An image forming apparatus comprising: a temperature sensor which detects a temperature inside the image forming apparatus; a developing unit which supplies developer to an image carrier and performs development; a supply unit which contains developer and supplies the contained developer to the developing unit; a control unit which executes developer replacement processing of discharging the developer from the developing unit and supplying the developer contained in the supply unit to the developing unit based on a first ratio of a developer supply time during which the supply unit performs supply of the developer for the developing unit and a drive time during which the developing unit is driven and a threshold value obtained based on a detected temperature of the temperature sensor; and a storage unit which stores a correspondence relationship between a value of the detected temperature and the threshold value, wherein the control unit obtains the threshold value from the correspondence relationship according to the detected temperature of the temperature sensor. ### Claim 2 (depends on 1) The apparatus according to claim 1, wherein the control unit performs the developer replacement processing for each color of the developer. ### Claim 3 (depends on 1) The apparatus according to claim 1, wherein the control unit cumulatively adds a first time during which supply of the developer is performed for the developing unit when image formation processing is performed and a second time during which the developing unit is driven when the image formation processing is performed respectively to calculate the developer supply time and the drive time and initializes the developer supply time and the drive time after the developer replacement processing is performed. ### Claim 4 (depends on 3) The apparatus according to claim 3, wherein the control unit adds the first time during which supply of the developer is performed for the developing unit and the second time during which the developing unit is driven when the developer replacement processing is performed to the developer supply time and the drive time to calculate the first ratio and repeatedly executes the developer replacement processing until the first ratio becomes less than the threshold value. ### Claim 5 (depends on 1) The apparatus according to claim 1, wherein the developer comprises a carrier and a toner. ### Claim 6 (depends on 5) The apparatus according to claim 5, wherein the the toner comprises a decolorable toner and a non-decolorable toner. ### Claim 7 (depends on 1) The apparatus according to claim 1, further comprising: a concentration sensor which detects a concentration of the toner contained in the developer, wherein the control unit determines whether a forcible supply operation, which drives the developing unit at all times until reaching a specified concentration and stirs a carrier and a newly supplied toner, is performed or not based on the detected value of the concentration sensor. ### Claim 8 (depends on 7) The apparatus according to claim 7, wherein the control unit initializes the developer supply time and the drive time after performing the forcible supply operation. ### Claim 9 (depends on 2) The apparatus according to claim 2, wherein the control unit performs the developer replacement processing for yellow toner, magenta toner, cyan toner, and black toner of the developer. ### Claim 10 A developer replacement method of an image forming apparatus including a developing unit which supplies developer to an image carrier and performs development, a supply unit which contains the developer and supplies the contained developer to the developing unit, and a temperature sensor which detects a temperature inside the image forming apparatus, the method comprising: calculating a first ratio of a developer supply time during which the supply unit performs supply of the developer for the developing unit and a drive time during which the developing unit is driven; performing developer replacing processing of discharging the developer from the developing unit and supplying the developer contained in the supply unit to the developing unit based on the first ratio and a threshold value obtained based on the detected temperature of the temperature sensor; storing a correspondence relationship between a value of the detected temperature and the threshold value; and obtaining the threshold value from the correspondence relationship according to the detected temperature. ### Claim 11 (depends on 10) The method according to claim 10, further comprising, by the image forming apparatus, cumulatively adding a time during which supply of the developer is performed for the developing unit when image formation processing is performed and a time during which the developing unit is driven when the image formation processing is performed respectively to calculate the developer supply time and the drive time and initializing the developer supply time and the drive time after the developer replacement processing is performed. ### Claim 12 (depends on 11) The method according to claim 11, further comprising, by the image forming apparatus, adding the time during which supply of the developer is performed for the developing unit and the time during which the developing unit is driven when the developer replacement processing is performed to the developer supply time and the drive time to calculate the first ratio and repeatedly executing the developer replacement processing until the first ratio becomes less than the threshold value. ### Claim 13 (depends on 10) The method according to claim 10, further comprising performing the developer replacement processing for each color of the developer. ### Claim 14 (depends on 10) The method according to claim 10, wherein the developer comprises a carrier and a toner. ### Claim 15 (depends on 14) The method according to claim 14, wherein the the toner comprises a decolorable toner and a non-decolorable toner. ### Claim 16 (depends on 10) The method according to claim 10, further comprising: detecting a concentration of the toner contained in the developer, and determining whether a forcible supply operation, which drives the developing unit at all times until reaching a specified concentration and stirs a carrier and a newly supplied toner, is performed or not based on the detected value. ### Claim 17 (depends on 16) The method according to claim 16, further comprising initializing the developer supply time and the drive time after performing the forcible supply operation. ### Claim 18 (depends on 10) The method according to claim 10, further comprising performing the developer replacement processing for yellow toner, magenta toner, cyan toner, and black toner of the developer. ### Claim 19 (depends on 10) The method according to claim 10, further comprising performing the developer replacement processing for black toner of the developer.