# US 2019/0162672 A1 · Image forming apparatus and determination method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0162672 A1 - Document ID: US20190162672A1 - Status: Published application - Kind: A1 - Application number: 16/322,236 - Filed: 2017-03-14 - Published: 2019-05-30 - Earliest claimed: 2016-08-10 - Assignees: Sharp Kabushiki Kaisha - Applicants: Sharp Kabushiki Kaisha - Inventors: YUSUKE SAKAKIBARA - Web page: https://patentgrep.com/patent/US20190162672A1 ## CPC - G01N 21/86: Investigating moving sheets (G01N21/89 takes precedence) - G01N 21/31: Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry {(G01N21/72 takes precedence)} - G01N 21/89: in moving material, e.g. running paper or textiles (G01N21/90, G01N21/91, G01N21/94 take precedence) - G01N 33/346: {Paper sheets} - G01N 2021/3129: {Determining multicomponents by multiwavelength light} - G01N 2021/8663: {Paper, e.g. gloss, moisture content} - G01N 2021/8917: {Paper, also ondulated} - G03G 2215/00616: Optical detector - G03G 2215/00751: of sheet type, e.g. OHP - G03G 2215/00776: of humidity or moisture influencing copy sheet handling - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract Provided is an image forming apparatus having a simplified sensor structure and configured to determine both the moisture content and paper type of paper. An image forming apparatus includes light-emitting units configured to illuminate paper—with a plurality of types of emission light having mutually different peak wavelengths, a light-receiving unit configured to receive reflected light, reflected from the paper, of the plurality of types of emission light, and a paper determination unit configured to determine the moisture content and the paper type of the paper, based on received-light intensities of the plurality of types of reflected light. ## Claims ### Claim 1 An image forming apparatus comprising: an illuminating unit configured to illuminate paper with a plurality of types of emission light having mutually different peak wavelengths; a light-receiving unit configured to receive a plurality of types of reflected light, reflected from the paper, of the plurality of types of emission light; and a determination unit configured to determine a moisture content and a paper type of the paper, based on received-light intensities of the plurality of types of reflected light received by the light-receiving unit. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein the light-receiving unit is a single unit. ### Claim 3 (depends on 1) The image forming apparatus according to claim 1 further comprising: a calculation unit configured to calculate an absorbance of the paper, based on a ratio between the received-light intensities of the plurality of types of reflected light received by the light-receiving unit and a reference received-light intensity, wherein the determination unit is configured to determine the moisture content and the paper type, based on the absorbance calculated by the calculation unit. ### Claim 4 (depends on 3) The image forming apparatus according to claim 3, wherein the determination unit is configured to determine the moisture content with a prescribed function prepared beforehand for a prescribed paper type and indicating a changing absorbance depending on the moisture content. ### Claim 5 (depends on 4) The image forming apparatus according to claim 4, wherein the determination unit is configured to determine the paper type with a plurality of the prescribed functions provided beforehand for each of a plurality of prescribed paper types. ### Claim 6 (depends on 1) The image forming apparatus according to claim 1, further comprising: a calculation unit, wherein the illuminating unit is configured to illuminate the paper with at least three types of emission light having mutually different peak wavelengths, the calculation unit is configured to calculate an absorbance of the paper, based on a ratio between a received-light intensity of reflected light, reflected from the paper, of one type of emission light of the at least three types of emission light and received-light intensities of reflected light, reflected from the paper, of the remaining two or more types of emission light, wherein the determination unit is configured to determine the moisture content and the paper type, based on the absorbance calculated by the calculation unit. ### Claim 7 (depends on 1) The image forming apparatus according to claim 1, wherein an optical axis of the plurality of types of emission light emitted by the illuminating unit or a normal line to a light-receiving surface of the light-receiving unit makes a not-perpendicular angle with the paper; and the light-receiving unit is configured to receive the plurality of types of reflected lights reflected regularly from the paper. ### Claim 8 (depends on 1) The image forming apparatus according to claim 1, further comprising: a filter configured to transmit light in a band containing a peak wavelength of one of the plurality of types of emission light and narrower than a band of the one of the plurality of types of emission light. ### Claim 9 (depends on 1) The image forming apparatus according to claim 1, further comprising: a light blocking part configured to block the plurality of types of emission light emitted by the illuminating unit directly towards the light-receiving unit. ### Claim 10 (depends on 1) The image forming apparatus according to claim 1, wherein the plurality of types of emission light have respective peak wavelengths that are different from each other by at least 10 nm. ### Claim 11 (depends on 1) The image forming apparatus according to claim 1, wherein the image forming apparatus is configured to form an image on the paper in accordance with an image forming condition set, based on a determination result by the determination unit. ### Claim 12 A method for determining a moisture content and a paper type of paper, the method comprising: making an illuminating unit illuminate the paper with a plurality of types of emission light having mutually different peak wavelengths; making a light-receiving unit receive a plurality of types of reflected light, reflected from the paper, of the plurality of types of emission light; and determining the moisture content and the paper type of the paper, based on received-light intensities of the plurality of types of reflected light.