US3791735A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital measuring apparatus
Assignee: Nikon Corp
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Filing: 1972-05-18
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Granted: 1974-02-12
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Expires: 1992-05-18
Abstract
Abstract A digital measuring apparatus for measuring the distance between two target lines formed on a test sample by the use of circular scanning or the like includes an optical pulse scale disposed in such a predetermined relationship with the target lines as to correct any measurement error resulting from circular (or angular) scanning. A scanning system is disposed to scan the target lines and the optical pulse scale in a predetermined relationship, thereby producing optical target-line position signals and optical pulse scale signals. Photoelectric converter means are provided to convert the optical target-line position signals and the optical pulse scale signals into respective electrical signals. Target-line position signal detector means may detect the target-line positions from one of the said electrical signals. The electrical signals passed through the target-line position signal detector means may be formed into gate signals by a gate circuit. The other electrical signals passed through the gate circuit are counted by counter means.
Inventors
- 👤 K Nakazawa
- 👤 S Sasayama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 23:33
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/14; G01B11/02
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
302 words
An apparatus for optically measuring the distance between two parallel reference lines on an object comprising: a focusing optical system for forming the image of said object, a rotary plate which has an optical pulse scale including at its peripheral portion parallel light transmitting portions and light intercepting portions alternately and equidistantly disposed in the circular direction, and which is rotatable within the focusing plane of said focusing system; a driving means for rotating said rotary plate; a photoconductive member fixed at its one end to the peripheral portion of said rotary plate so that the image of said object may be scanned optically by the rotation of said rotary plate and so that said photoconductive member may receive the optical signals of said reference lines; a first photoelectric conversion means for converting the optical signals transmitted through said photoconductive member to electrical signals; a pulse signal generating means including a point optical source which illuminates said optical pulse scale at least during the time interval from a time when one of said two reference lines is scanned by said photoconductive member to a time when the other reference line is scanned, and a second photoelectric conversion means for converting the optical pulse signals passing through said optical pulse scale to electrical pulse signals; a wave form shaping means for shaping said electrical pulse signals to provide rectangular wave signals; an AND circuit having two input terminals one of which receives said rectangular wave signals and the other receives said electrical pulse signals from said second photoelectric conversion means so that said electrical signals are gated by said rectangular wave signals to provide, as output signals, electrical pulse signals corresponding to said rectangular wave signals; and a counter means for counting the number of said electrical signals passing through said AND circuit.
Claim 2
Independent Claim
302 words
An apparatus for optically measuring the distance between two parallel reference lines on an object comprising: a focusing optical system for forming the image of said object, a rotary plate which has an optical pulse scale including at its peripheral portion parallel light transmitting portions and light intercepting portions alternately and equidistantly disposed in the circular direction, and which is rotatable within the focusing plane of said focusing system; a driving means for rotating said rotary plate; a photoconductive member fixed at its one end to the peripheral portion of said rotary plate so that the image of said object may be scanned optically by the rotation of said rotary plate and so that said photoconductive member may receive the optical signals of said reference lines; a first photoelectric conversion means for converting the optical signals transmitted through said photoconductive member to electrical signals; a pulse signal generating means including a point optical source which illuminates said optical pulse scale at least during the time interval from a time when one of said two reference lines is scanned by said photoconductive member to a time when the other reference line is scanned, and a second photoelectric conversion means for converting the optical pulse signals passing through said optical pulse scale to electrical pulse signals; a wave form shaping means for shaping said electrical pulse signals to provide rectangular wave signals; an AND circuit having two input terminals one of which receives said rectangular wave signals and the other receives said electrical pulse signals from said second photoelectric conversion means so that said electrical signals are gated by said rectangular wave signals to provide, as output signals, electrical pulse signals corresponding to said rectangular wave signals; and a counter means for counting the number of said electrical signals passing through said AND circuit.
Claim 3
Independent Claim
287 words
An apparatus for optically measuring the distance between two parallel reference lines on an object comprising: a laser source; a rotary plate which has an optical pulse scale including at its peripheral portion parallel light transmitting portions and light intercepting portions disposed alternatively and equidistantly in the circular direction, and which is rotatable; a driving source for rotating said rotary plate; a reflecting member fixed at the rotary center of said rotary plate for reflecting laser light from said laser source so that said object may be scanned by the rotation of said rotary plate; a first photoelectric conversion means which receives the optical signals reflected by said object and converts said optical signals to electrical signals; a pulse generating means including a point light source which illuminates said optical scale at least during the time interval from a time when one of said two reference lines is scanned by the rotation of said reflecting member to a time when the other of said two reference lines is scanned, and a second photoelectric conversion means for converting to electrical pulse signals light pulse signals generated from said point light source and passed through said optical pulse scale; a wave form shaping means for shaping the electrical signAls from said first photoelectric conversion means to provide rectangular wave signals; an AND circuit having two input terminals one of which receives said rectangular wave signals and the other receives said electric pulse signals from said second photoelectric conversion means so that said electrical signals are gated by said rectangular wave signals to provide, as output signals, electric pulse signals corresponding to said rectangular wave signals; and a counter means for counting electric pulse signals passing through said AND circuit.
Claim 4
Independent Claim
287 words
An apparatus for optically measuring the distance between two parallel reference lines on an object comprising: a laser source; a rotary plate which has an optical pulse scale including at its peripheral portion parallel light transmitting portions and light intercepting portions disposed alternatively and equidistantly in the circular direction, and which is rotatable; a driving source for rotating said rotary plate; a reflecting member fixed at the rotary center of said rotary plate for reflecting laser light from said laser source so that said object may be scanned by the rotation of said rotary plate; a first photoelectric conversion means which receives the optical signals reflected by said object and converts said optical signals to electrical signals; a pulse generating means including a point light source which illuminates said optical scale at least during the time interval from a time when one of said two reference lines is scanned by the rotation of said reflecting member to a time when the other of said two reference lines is scanned, and a second photoelectric conversion means for converting to electrical pulse signals light pulse signals generated from said point light source and passed through said optical pulse scale; a wave form shaping means for shaping the electrical signAls from said first photoelectric conversion means to provide rectangular wave signals; an AND circuit having two input terminals one of which receives said rectangular wave signals and the other receives said electric pulse signals from said second photoelectric conversion means so that said electrical signals are gated by said rectangular wave signals to provide, as output signals, electric pulse signals corresponding to said rectangular wave signals; and a counter means for counting electric pulse signals passing through said AND circuit.
Claim 5
Dependent Claim
32 words
Apparatus according to claim 2, wherein said point light source is laser light divided by a beam splitter provided in the optical path of the laser light generated from said laser source.
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) | 1977-02-11 | 1977-08-13 | 1978-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-02-11 | 1981-08-13 | 1982-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-02-11 | 1985-08-13 | 1986-02-12 | $7700.00 | Window Closed / Lapsed |