# US 5,706,071 A · Line of sight detection apparatus and an equipment having the line of sight detection apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,706,071 A - Document ID: US5706071A - Status: Granted - Kind: A - Application number: 08/580,449 - Filed: 1995-12-27 - Granted: 1998-01-06 - Earliest claimed: 1994-12-28 - Assignees: Canon Kabushiki Kaisha - Inventors: Tatsuyuki Tokunaga - Web page: https://patentgrep.com/patent/US5706071A ## CPC - G03B 13/02: Viewfinders - G03B 17/20: visible in viewfinder - G03B 2213/025: Sightline detection - G03B: APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR (optical parts of such apparatus G02B; photosensitive materials or processes for photographic purposes G03C; apparatus for processing exposed photographic materials G03D) ## Abstract A device for detecting a line of sight includes an image pick-up element for picking up an eyeball image of a user, a line of sight detection circuit for detecting the line of sight of the user by calculating an output from the image pick-up element, a maximum value detection circuit for detecting a maximum output value output from the image pick-up element, a comparison circuit for comparing the maximum value with a predetermined threshold value, and an inhibition circuit for inhibiting a line of sight detection operation of the line of sight detection circuit when the maximum value is smaller than the threshold value. ## Claims ### Claim 1 A device for detecting a line of sight, comprising: a) image pick-up means for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user by calculating an output from said image pick-up means; c) maximum value detection means for detecting a maximum output value output from said image pick-up means; d) comparison means for comparing said maximum value with a predetermined threshold value; and e) inhibition means for inhibiting a line of sight detection operation of said line of sight detection means when said maximum value is smaller than said threshold value. ### Claim 2 (depends on 1) A device according to claim 1, wherein said image pick-up means comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 3 (depends on 1) A device according to claim 1, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 4 (depends on 3) A device according to claim 3, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 5 (depends on 1) A device according to claim 1, wherein said maximum value detection means detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up means in units of blocks. ### Claim 6 A device for detecting a line of sight, comprising: a) image pick-up means for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user on the basis of an output from said image pick-up means; c) maximum value detection means for detecting a maximum output value output from said image pick-up means; d) determination means for determining if said maximum value satisfies a predetermined condition; and e) inhibition means for inhibiting a line of sight detection operation of said line of sight detection means when said determination means determines that said maximum value does not satisfy said predetermined condition. ### Claim 7 (depends on 6) A device according to claim 6, wherein said image pick-up means comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 8 (depends on 6) A device according to claim 6, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 9 (depends on 8) A device according to claim 8, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 10 (depends on 6) A device according to claim 6, wherein said maximum value detection means detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up means in units of blocks. ### Claim 11 A device for detecting a line of sight, comprising: a) image pick-up means, having a plurality of picture elements, for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user on the basis of an output from said image pick-up means; c) determination means for determining if a picture element that satisfies a predetermined condition is present in said plurality of picture elements; and d) inhibition means for inhibiting a line of sight detection operation of said line of sight detection means when said determination means determines that any picture element that satisfies said predetermined condition is not present in said plurality of picture elements. ### Claim 12 (depends on 11) A device according to claim 11, wherein said image pick-up means comprises a storage type image sensor which allows a non-destructive reading operation. ### Claim 13 (depends on 11) A device according to claim 11, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 14 (depends on 13) A device according to claim 13, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 15 (depends on 13) A device according to claim 13, wherein said predetermined condition is that said eyeball image picked up by said image pick-up means includes the Purkinje image. ### Claim 16 (depends on 11) A device according to claim 11, wherein said predetermined condition is that an absolute value of a picture element output is equal to or larger than a first predetermined value, and an output difference between the picture element output and an adjacent picture element is equal to or larger than a second predetermined value different from the first predetermined value. ### Claim 17 A device for detecting a line of sight, comprising: a) image pick-up means for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user on the basis of an output from said image pick-up means; c) maximum value detection means for detecting a maximum output value output from said image pick-up means; d) determination means for determining if said maximum value satisfies a predetermined condition; and e) line of sight detection control means for, when said determination means determines that said maximum value satisfies said predetermined condition, permitting a line of sight detection operation of said line of sight detection means, and for, when said determination means determines that said maximum value does not satisfy said predetermined condition, inhibiting the line of sight detection operation of said line of sight detection means. ### Claim 18 (depends on 17) A device according to claim 17, wherein said image pick-up means comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 19 (depends on 17) A device according to claim 17, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 20 (depends on 19) A device according to claim 19, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 21 (depends on 17) A device according to claim 17, wherein said maximum value detection means detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up means in units of blocks. ### Claim 22 A device for detecting a line of sight, comprising: a) an image pick-up element for picking up an eyeball image of a user; b) a line of sight detection circuit for detecting the line of sight of said user on the basis of an output from said image pick-up element; c) a maximum value detection circuit for detecting a maximum output value output from said image pick-up element; d) a determination circuit for determining if said maximum value satisfies a predetermined condition; and e) an inhibition circuit for inhibiting a line of sight detection operation of said line of sight detection circuit when said determination circuit determines that said maximum value does not satisfy said predetermined condition. ### Claim 23 (depends on 22) A device according to claim 22, wherein said image pick-up element comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 24 (depends on 22) A device according to claim 22, wherein said line of sight detection circuit detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up element. ### Claim 25 (depends on 24) A device according to claim 24, wherein said line of sight detection circuit detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up element. ### Claim 26 (depends on 22) A device according to claim 22, wherein said maximum value detection circuit detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up element in units of blocks. ### Claim 27 (depends on 22) A device according to claim 22, wherein said line of sight detection circuit, said maximum value detection circuit, said determination circuit, and said inhibition circuit comprise a microcomputer, and said microcomputer executes a predetermined algorithm. ### Claim 28 An equipment having a device for detecting a line of sight, comprising: a) image pick-up means for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user by calculating an output from said image pick-up means; c) maximum value detection means for detecting a maximum output value output from said image pick-up means; d) comparison means for comparing said maximum value with a predetermined threshold value; and e) inhibition means for inhibiting a line of sight detection operation of said line of sight detection means when said maximum value is smaller than said threshold value. ### Claim 29 (depends on 28) An equipment according to claim 28, wherein said image pick-up means comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 30 (depends on 28) An equipment according to claim 28, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 31 (depends on 30) An equipment according to claim 30, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 32 (depends on 28) An equipment according to claim 28, wherein said maximum value detection means detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up means in units of blocks. ### Claim 33 An equipment having a device for detecting a line of sight, comprising: a) image pick-up means for picking up an eyeball image of a user; b) line of sight detection means for detecting the line of sight of said user on the basis of an output from said image pick-up means; c) maximum value detection means for detecting a maximum output value output from said image pick-up means; d) determination means for determining if said maximum value satisfies a predetermined condition; and e) inhibition means for inhibiting a line of sight detection operation of said line of sight detection means when said determination means determines that said maximum value does not satisfy said predetermined condition. ### Claim 34 (depends on 33) An equipment according to claim 33, wherein said image pick-up means comprises a storage type image sensor which has a plurality of picture elements, and allows a non-destructive reading operation. ### Claim 35 (depends on 33) An equipment according to claim 33, wherein said line of sight detection means detects the line of sight of said user by detecting at least a position of a Purkinje image from said eyeball image picked up by said image pick-up means. ### Claim 36 (depends on 35) An equipment according to claim 35, wherein said line of sight detection means detects the line of sight of said user by detecting a relative position between the Purkinje image and a pupil from said eyeball image picked up by said image pick-up means. ### Claim 37 (depends on 33) An equipment according to claim 33, wherein said maximum value detection means detects maximum values in units of blocks by reading a plurality of picture elements included in said image pick-up means in units of blocks.