US3833807A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital length measuring means
Assignee: Pentax Corp
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Filing: 1973-06-08
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Granted: 1974-09-03
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Expires: 1993-06-08
Abstract
Abstract A digital length measuring means including a transparency diffraction grating, a base plate having a mirror plane which is inclined with respect to the surface of the grating and an optical system arranged with respect to said diffraction grating and said base plate to produce Moire fringe contour lines, which are photoelectrically transformed into pulses which indicate certain unit lengths of relative shift of the Moire fringe lines caused by moving said diffraction grating and said optical system as a unit in a direction perpendicular to the grating lines. In a variation, two or more photoelectric elements may be provided to divide into equal parts one period of the Moire fringe lines produced at the image forming plane of the optical system. Also the transparency diffraction grating may be formed of two complex gratings whose grating lines are shifted by onefourth pitch from each other, and two photoelectric transforming devices are provided corresponding to each of these two gratings so that the pulses indicating unit length are more finely divided. In another variation, the mirror plane of the base plate placed opposite to the transparency diffraction grating is formed with a triangular waveform and is positioned parallel to the grating surface.
Inventors
- 👤 H Takeda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 19:15
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01D5/366; G01D5/38
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
126 words
Digital length measuring apparatus comprising: a single transparency diffraction grating; a base plate having a mirror plane inclined with respect to the surface of the grating; an optical system arranged with respect to the grating and the mirror plane to produce fringe contour lines on the mirror plane including a light source for directing light through the grating onto the mirror plane and photoelectric means for observing the contour lines; means for moving one of said grating, base plate and optical system in a manner to produce shifting of said fringe lines in a direction to intersect the diffraction grating lines; and electric circuit means for transforming the signals from said photoelectric means into pulses which indicate unit length of said shifting of said fringe lines.
Claim 2
Dependent Claim
126 words
Digital length measuring apparatus comprising: a single transparency diffraction grating; a base plate having a mirror plane inclined with respect to the surface of the grating; an optical system arranged with respect to the grating and the mirror plane to produce fringe contour lines on the mirror plane including a light source for directing light through the grating onto the mirror plane and photoelectric means for observing the contour lines; means for moving one of said grating, base plate and optical system in a manner to produce shifting of said fringe lines in a direction to intersect the diffraction grating lines; and electric circuit means for transforming the signals from said photoelectric means into pulses which indicate unit length of said shifting of said fringe lines.
Claim 3
Dependent Claim
17 words
The apparatus of claim 1 wherein said optical system and said grating are movable as a unit.
Claim 4
Dependent Claim
57 words
The apparatus of claim 1 wherein said optical system includes a mirror receiving light from the light source and reflecting it through the grating onto the base plate; and including means for mounting as a unit the mirror, the grating, and the photoelectric means; and means for moving said unit in a direction intersecting the grating lines.
Claim 5
Dependent Claim
27 words
The apparatus of claim 1 wherein said photoelectric means includes photoelectric elements positioned to divide into parts one period between fringe lines produced at said mirror plane.
Claim 6
Dependent Claim
45 words
The apparatus of claim 1 wherein said grating comprises two complex gratings whose grating lines are shifted from each other and said photoelectric means include two photoelectric transforming devices arranged with respect to the gratings so that the pulses indicating unit length are finely divided.
Claim 7
Dependent Claim
45 words
The apparatus of claim 1 wherein the base plate is formed with a triangular waveform having a mirrored surface and the base plate extends generally parallel to the diffraction grating while the mirror surfaces of the base plate are angled with respect to the grating.
Claim 8
Independent Claim
89 words
A method of digitally measuring length comprising the steps of: directing a source of light through a single diffraction grating onto a mirror plane inclined with respect to said grating surface to form fringe contour lines; observing the contour lines at a point on the plane with photoelectric means; moving the apparatus in a manner to shift said fringe lines in a direction intersecting the diffraction grating lines; and transforming the signals from the photoelectric means into pulses which indicate unit length of said shifting of said fringe lines.
Claim 9
Independent Claim
89 words
A method of digitally measuring length comprising the steps of: directing a source of light through a single diffraction grating onto a mirror plane inclined with respect to said grating surface to form fringe contour lines; observing the contour lines at a point on the plane with photoelectric means; moving the apparatus in a manner to shift said fringe lines in a direction intersecting the diffraction grating lines; and transforming the signals from the photoelectric means into pulses which indicate unit length of said shifting of said fringe lines.
Claim 10
Dependent Claim
33 words
The method of claim 7 including moving the diffraction grating, the light source and the photoelectric means as a unit relative to the mirror plane to cause said shifting of the fringe lines.
Claim 11
Dependent Claim
26 words
The method of claim 7 including observing with said photoelectric means the mirror plane in a manner to divide into parts one period between fringe lines.
Claim 12
Dependent Claim
45 words
The method of claim 7 wherein said grating comprises two complex gratings whose grating lines are shifted from each other and said photoelectric means include two photoelectric transforming devices arranged with respect to the gratings so that the pulses indicating unit length are finely divided.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-09-02 | 1978-03-04 | 1978-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-09-02 | 1982-03-04 | 1982-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-09-02 | 1986-03-04 | 1986-09-03 | $7700.00 | Window Closed / Lapsed |