# US 8,786,653 B2 · Light quantity control device, exposure device, and 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 8,786,653 B2 - Document ID: US8786653B2 - Status: Granted - Kind: B2 - Application number: 13/763,866 - Filed: 2013-02-11 - Published: 2014-03-13 - Granted: 2014-07-22 - Earliest claimed: 2012-09-12 - Assignees: Fuji Xerox Co., Ltd. - Applicants: Fuji Xerox Co., Ltd. - Inventors: Satoshi Kurashima - Web page: https://patentgrep.com/patent/US8786653B2 ## CPC - G03G 15/04036: {Details of illuminating systems, e.g. lamps, reflectors (lamp housings for copying cameras, reflex exposure lighting G03B27/542)} - G03G 15/04054: {by LED arrays} - H01S 5/0264: {for monitoring the laser-output} - H01S 5/0683: by monitoring the optical output parameters - G03G 15/50: {Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control (sequencing control G03G21/14)} - H01S 5/042: Electrical excitation {; Circuits therefor (monolithically integrated laser drive components H01S5/0261)} - H01S 5/4025: {Array arrangements, e.g. constituted by discrete laser diodes or laser bar (H01S5/42 takes precedence)} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY - H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL ## Abstract A light quantity control device includes a light quantity detecting unit and an output unit. The light quantity detecting unit detects a quantity of laser light emitted from semiconductor laser elements which are mounted on plural mount devices. The output unit is provided on at least a reference mount device among the plural mount devices and outputs, to another mount device other than the reference mount device among the plural mount devices, an output result which is obtained through comparison and correction of a value detected by the light quantity detecting unit and a reference value. ## Claims ### Claim 1 A light quantity control device comprising: a light quantity detecting unit that detects a quantity of laser light emitted from semiconductor laser elements which are mounted on a plurality of circuit devices; and an output unit that is provided on at least a reference circuit device among the plurality of circuit devices and that outputs, to another circuit device other than the reference circuit device among the plurality of circuit devices, an output result which is obtained through comparison and correction of a value detected by the light quantity detecting unit and a reference value, wherein each of the plurality of circuit devices includes: a reference current generating unit that generates a reference current, a comparison and correction unit that compares the reference current with a photocurrent which is output from the light quantity detecting unit, after converting the reference current and the photocurrent to voltages, and that performs correction so that the voltages are made equal to each other, a current controller that controls, in accordance with an output result obtained from the comparison and correction unit, a driving current for driving the semiconductor laser elements; and an operation stopping unit that is electrically coupled to the reference current generating unit and the comparison and correction unit, wherein the operation stopping units are configured to stop the operation of the reference current generating unit and the comparison and correction unit of the another circuit device other than the reference circuit device among the plurality of circuit devices. ### Claim 2 (depends on 1) The light quantity control device according to claim 1, wherein each of the plurality of circuit devices further includes a memory that stores the output result obtained from the comparison and correction unit. ### Claim 3 (depends on 1) The light quantity control device according to claim 1, wherein each of the plurality of circuit devices further includes an analog-to-digital converting unit that performs analog-to-digital conversion on the output result obtained from the comparison and correction unit. ### Claim 4 (depends on 3) The light quantity control device according to claim 3, wherein each of the plurality of circuit devices outputs the output result which has been converted to a digital signal by the analog-to-digital converting unit, the output result being output as a parallel signal. ### Claim 5 (depends on 3) The light quantity control device according to claim 3, wherein each of the plurality of circuit devices outputs the output result which has been converted to a digital signal by the analog-to-digital converting unit, the output result being output as a serial signal. ### Claim 6 (depends on 1) The light quantity control device according to claim 1, further comprising: a switching unit that switches between the reference circuit device and the other circuit device. ### Claim 7 (depends on 1) An exposure device comprising: a plurality of semiconductor laser elements; the light quantity control device according to claim 1, the light quantity control device controlling a quantity of laser light emitted from the plurality of semiconductor laser elements; and an optical scanning system that causes a surface of a photoconductor to be exposed in a scanning manner to the laser light emitted from the plurality of semiconductor laser elements. ### Claim 8 (depends on 7) An image forming apparatus comprising: the exposure device according to claim 7; and a photoconductor that is exposed in a scanning manner to laser light by the exposure device in accordance with image data. ### Claim 9 A light quantity control device comprising: a light quantity detecting unit that detects a quantity of laser light emitted from semiconductor laser elements which are mounted on a plurality of circuit devices; and an output unit that is provided on at least a reference circuit device among the plurality of circuit devices and that outputs, to another circuit device other than the reference circuit device among the plurality of circuit devices, an output result which is obtained through comparison and correction of a value detected by the light quantity detecting unit and a reference value, wherein each of the plurality of circuit devices includes: a reference voltage generating unit that generates a reference voltage, a comparison and correction unit that compares the reference voltage with a photocurrent which is output from the light quantity detecting unit, after converting the photocurrent to a voltage, and that performs correction so that the reference voltage and the converted voltage are made equal to each other, a current controller that controls, in accordance with an output result obtained from the comparison and correction unit, a driving current for driving the semiconductor laser elements; and an operation stopping unit that is electrically coupled to the reference voltage generating unit and the comparison and correction unit, wherein the operation stopping units are configured to stop the operation of the reference voltage generating unit and the comparison and correction unit of the another circuit device other than the reference circuit device among the plurality of circuit devices. ### Claim 10 (depends on 9) The light quantity control device according to claim 9, wherein each of the plurality of circuit devices further includes a memory that stores the output result obtained from the comparison and correction unit. ### Claim 11 (depends on 9) The light quantity control device according to claim 9, wherein each of the plurality of circuit devices further includes an analog-to-digital converting unit that performs analog-to-digital conversion on the output result obtained from the comparison and correction unit. ### Claim 12 (depends on 11) The light quantity control device according to claim 11, wherein each of the plurality of circuit devices outputs the output result which has been converted to a digital signal by the analog-to-digital converting unit, the output result being output as a parallel signal. ### Claim 13 (depends on 11) The light quantity control device according to claim 11, wherein each of the plurality of circuit devices outputs the output result which has been converted to a digital signal by the analog-to-digital converting unit, the output result being output as a serial signal.