# US 5,708,271 A · Non-destructive sugar content measuring apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,708,271 A - Document ID: US5708271A - Status: Granted - Kind: A - Application number: 08/577,542 - Filed: 1995-12-22 - Granted: 1998-01-13 - Earliest claimed: 1994-12-28 - Assignees: Sumitomo Metal Mining Co., Ltd. - Inventors: Masahiro Ito; Junji Iida; Akira Terashima; Toshiki Kishimoto - Web page: https://patentgrep.com/patent/US5708271A ## CPC - G01N 33/025: {Fruits or vegetables} - G01N 21/3563: for analysing solids; Preparation of samples therefor - G01N 21/359: using near infrared light - G01N 2021/8466: {Investigation of vegetal material, e.g. leaves, plants, fruits} - Y10S 250/91: Food sample analysis using invisible radiant energy source - 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) - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract A non-destructive sugar content measuring apparatus for determining the sugar content of a vegetable or fruit by measuring absorption of light in sugar when near infrared light is made incident on the vegetable or fruit; comprising at least one light source that emits light rays having three kinds of wavelengths within a wavelength range of from 860 nm to 960 nm, and a detector that detects the absorption of light. The detector is disposed at a position except the position on an extended line of a straight line that connects i) the center of a light-incident area formed on the surface of the vegetable or fruit by the light emitted from the light source and incident on the vegetable or fruit and ii) the center of the vegetable or fruit, and at the same time at a position where the light-incident area formed on the surface of the vegetable or fruit by the incident light and the detection area formed on the surface of the vegetable or fruit by the light emergent from the vegetable or fruit and to be received by the detector do not overlap each other. This apparatus effectively enables non-destructive measurement of sugar content of vegetables and fruits in an accuracy of about plus-minus 1.0.degree.Brix, which is a resolving limit of sugar content that can be perceived by humans. ## Claims ### Claim 1 A non-destructive sugar content measuring apparatus for determining the sugar content of a vegetable or fruit by measuring absorption of light in sugar when near infrared light is made incident on the vegetable or fruit; said apparatus comprising: at least one light source that emits a first light ray having a wavelength ranging between 860 nm and 890 nm, a second light ray having a wavelength ranging between 900 nm and 920 nm and a third light ray having a wavelength ranging between more than 920 nm and not more than 960 nm, and a detector that detects the absorption of light; said detector being disposed at a position except the position on an extended line of a straight line that connects i) the center of a light-incident area formed on the surface of the vegetable or fruit by the light emitted from the light source and incident on the vegetable or fruit, and (ii) the center of the vegetable or fruit, and at the same time at a position where the light-incident area formed on the surface of the vegetable or fruit by the incident light and a detection area formed on the surface of the vegetable or fruit by the light emergent from the vegetable or fruit and to be received by the detector do not overlap each other. ### Claim 2 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said vegetable or fruit is a muskmelon, and an angle formed by i) a straight line that connects the center of a light-incident area formed on the surface of the muskmelon by the light incident thereon and the center of the muskmelon and ii) a straight line that connects the center of a detection area formed on the surface of the muskmelon by the light emergent therefrom and the center of the muskmelon is set at from 40 degrees to 80 degrees. ### Claim 3 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said vegetable or fruit is a muskmelon, and the linear distance corresponding to a straight line connecting the center of the light-incident area formed on the surface of the muskmelon by the incident light and the center of a detection area formed on the surface of the muskmelon by the emergent light is set at from 4 cm to 13 cm. ### Claim 4 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said vegetable or fruit is a watermelon, and the linear distance corresponding to a straight line connecting the center of the light-incident area formed on the surface of the watermelon by the incident light and the center of a detection area formed on the surface of the watermelon by the emergent light is set at from 4 cm to 12 cm. ### Claim 5 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein the incident direction of the light emitted from the light source and incident on the surface of the vegetable or fruit is set in the direction not in agreement with the direction extended from a straight line connecting the center of the light-incident area formed on the surface of the vegetable or fruit by the incident light and the center of the vegetable or fruit. ### Claim 6 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said light source is a semiconductor laser. ### Claim 7 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said light source is a solid-state laser. ### Claim 8 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said light source is a light-emitting diode. ### Claim 9 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said second light ray has a wavelength ranging between 900 and 905 nm or between 910 nm and 915 nm, and said third light ray has a wavelength ranging between more than 920 nm and not more than 925 nm. ### Claim 10 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said second light ray has a wavelength ranging between more than 905 nm and not more than 910 nm, and said third light ray has a wave length ranging between more than 920 nm and not more than 925 nm. ### Claim 11 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said third light ray has a wavelength ranging between more than 925 nm and not more than 930 nm. ### Claim 12 (depends on 1) The non-destructive sugar content measuring apparatus according to claim 1, wherein said third light ray has a wavelength ranging between more than 930 nm and not more than 940 nm. ### Claim 13 (depends on 1, 2, 3, 4, 5, 6, 7, 8) The non-destructive sugar content measuring apparatus according to any one of claims 1 to 8, wherein said vegetable or fruit is a muskmelon, said first to third light rays emitted from at least one light source and incident on the muskmelon have equal extent of the light-incident area and equal light intensity distribution in the light-incident area on the surface of the muskmelon, and the extent of light-incident area is set within the range of from 1 cm.sup.2 to 20 cm.sup.2. ### Claim 14 (depends on 13) The non-destructive sugar content measuring apparatus according to claim 13, wherein said first to third light rays emitted from at least one light source and incident on the muskmelon are passed through a diffuser panel so that the incident light rays have equal light intensity distribution in the light-incident area on the surface of the muskmelon. ### Claim 15 (depends on 1, 2, 3, 4, 5, 6, 7, 8) The non-destructive sugar content measuring apparatus according to any one of claims 1 to 8, wherein said vegetable or fruit is a fruit, and the light-incident area formed on the surface of the fruit by the incident light and/or the detection area formed on the surface of the fruit by the light emergent from the fruit and to be received by the detector is set at a position within the range of from 1/50 to 1/3 of the overall height of the fruit as viewed with its pedicel portion up.