# US 2008/0185505 A1 · Encoder and Light Receiving Device For Encoder > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0185505 A1 - Document ID: US20080185505A1 - Status: Published application - Kind: A1 - Application number: 11/883,070 - Filed: 2006-10-10 - Published: 2008-08-07 - Earliest claimed: 2005-10-13 - Assignees: Hamamatsu Photonics K.K. - Inventors: Seiichiro Mizuno; Yoshitaka Terada; Hitoshi Inoue; Takayuki Suzuki - Web page: https://patentgrep.com/patent/US20080185505A1 ## CPC - G01D 5/3473: {Circular or rotary encoders} - G01D: MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR ## Abstract There is provided an encoder in which the absolute angle can be detected with high accuracy even when the irradiated position of light to be detected with respect to a scale is displaced from a reference, and a photodetecting device for an encoder used for such an encoder. In the encoder 1, by passing light to be detected through a straight-line light transmitting portion 17, a bright portion 19 to which the light to be detected is irradiated is formed in an area of a scale plate 11 containing mutually separate parts of arranged lines L1 and L2 and also a dark portion 20 to which no light to be detected is irradiated is formed in the other area. Accordingly, a relative angle between light intensity peaks P1 and P2 (reference relative angle) can be uniquely calculated based on the shape of the light transmitting portion 17. Therefore, in the encoder 1, even if the irradiated position of the light to be detected with respect to the scale plate 11 is displaced from the reference, the absolute angle can be detected with high accuracy by calculating a deviation amount of a relative angle on detecting the angle from the reference relative angle as a corrected amount α°. ## Claims ### Claim 1 An encoder comprising: a rotating member; a light source device for emitting light to be detected to the rotating member; and a photodetecting device including a scale having a plurality of photodetecting elements arranged thereon, and an output portion for outputting an output signal based on light intensity of the light to be detected made incident to the photodetecting elements through the rotating member, wherein the photodetecting elements are arranged along an annularly arranged line on the scale, and the rotating member is designed so that, in the scale, an area containing mutually separate parts of the arranged line is set as a bright portion to which the light to be detected is irradiated, and an area containing the other portion excluding the parts of the arranged line concerned is set as a dark portion to which no light to be detected is irradiated. ### Claim 2 (depends on 1) The encoder according to claim 1, wherein a straight-line light transmitting portion is formed in the rotating member, and the bright portion is formed of the light to be detected that has passed through the light transmitting portion. ### Claim 3 (depends on 2) The encoder according to claim 2, wherein for the light transmitting portion, a width of one end side is different from a width of the other end side. ### Claim 4 (depends on 2) The encoder according to claim 2, wherein the light transmitting portion is a slit. ### Claim 5 (depends on 1) The encoder according to claim 1, wherein a straight-line light reflecting portion is formed in the rotating member, and the bright portion is formed of the light to be detected reflected from the light reflecting portion. ### Claim 6 (depends on 5) The encoder according to claim 5, wherein for the light reflecting portion, a width of one end side is different from a width of the other end side. ### Claim 7 (depends on 1) The encoder according to claim 1, wherein the photodetecting elements are arranged in a zigzag form along the arranged line. ### Claim 8 (depends on 1) The encoder according to claim 1, wherein, in the scale, a light absorbing film is formed in an area excluding the area where the photodetecting elements are arranged. ### Claim 9 A photodetecting device for an encoder comprising: a scale having a plurality of photodetecting elements arranged thereon; and an output portion for outputting an output signal based on light intensity of light to be detected made incident to the photodetecting elements, wherein the photodetecting elements are arranged along an annularly arranged line on the scale, and in the scale, a light absorbing film is formed in an area excluding the area where the photodetecting elements are arranged. ### Claim 10 (depends on 9) The photodetecting device for an encoder according to claim 9, wherein the output portion has a shift register that makes the output signal based on light intensity output in sequence from the photodetecting elements, and the shift register is arranged inside the arranged line. ### Claim 11 (depends on 9) The photodetecting device for an encoder according to claim 9, wherein the photodetecting elements are arranged in a zigzag form along the arranged line.