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US3885872A
Expired / Lapsed
US
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Digital proximity sensing system
Assignee: International Business Machines Corp
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Filing: 1973-06-12
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Granted: 1975-05-27
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Expires: 1993-06-12
Abstract
Abstract A digital proximity sensing system includes a light source, a pair of photosensitive transducers such as phototransistors, one of which is arranged to have a first voltage output characteristic with respect to the distance between the object to be sensed and the photosensitive transducer and the other of which is arranged to have a second voltage output characteristic with respect to the distance between the object to be measured and the photosensitive transducer differing from said first characteristic. The respective outputs from the photosensitive transducers are amplified by a pair of amplifiers of which one is adjustable. The amplified outputs are then compared to determine which voltage signal is greater. An initial adjustment is made with an object at a predetermined distance Do, so that the voltage outputs of the respective amplifiers are equal. The relative magnitude of the voltage outputs of the respective amplifiers as compared results in an indication of the position of the object to be sensed relative to the predetermined distance Do.
Inventors
- 👤 Jr James J Howe
- 👤 James C Yarrington
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 15:40
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01B; G01B11/00; G01B11/02; G01B11/026
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
124 words
A proximity sensor comprising: a light source, first and second photosensitive elements responsive to light from said source reflected from an object, said first photosensitive element being positioned to receive light from said source directly reflected from said object, said second photosensitive element being positioned to receive light from said source diffusively reflected from said object, and means for comparing outputs from said photosensitive elements to obtain an indication of proximity, wherein said photosensitive elements have differing output characteristics with respect to displacement between said photosensitive elements and said object, said characteristics each comprising a voltagedisplacement relationship in which the voltage decreases with respect to increase in displacement, said characteristics having an intersection with each other at a nominal predeterminEd displacement from said object.
Claim 2
Dependent Claim
124 words
A proximity sensor comprising: a light source, first and second photosensitive elements responsive to light from said source reflected from an object, said first photosensitive element being positioned to receive light from said source directly reflected from said object, said second photosensitive element being positioned to receive light from said source diffusively reflected from said object, and means for comparing outputs from said photosensitive elements to obtain an indication of proximity, wherein said photosensitive elements have differing output characteristics with respect to displacement between said photosensitive elements and said object, said characteristics each comprising a voltagedisplacement relationship in which the voltage decreases with respect to increase in displacement, said characteristics having an intersection with each other at a nominal predeterminEd displacement from said object.
Claim 3
Dependent Claim
45 words
Apparatus according to claim 1 wherein said means for comparing further comprises: first and second amplifiers, one of said amplifiers having an adjustable gain characteristic; and a voltage comparator for providing a digital output signal determined by relative magnitudes of output signals from said amplifiers.
Claim 4
Dependent Claim
169 words
Apparatus for determining displacement of an object with respect to a reference point, comprising: a light source for providing illumination of said object; a first photosensitive element disposed to receive light directly reflected from said source, and having a first electrical output characteristic which is proportional to displacement from said first photosensitive element to said object; a second photosensitive element disposed to receive light diffusively reflected from said source, and having a second electrical output characteristic which is proportional to displacement between said second photosensitive element and said object and different from said first characteristic; and means for comparing an output from said first photosensitive element with an output from said second photosensitive element to determine the relative displacement of said object with respect to a predetermined reference point, said characteristics each comprising a voltage-displacement relationship in which the voltage decreases with respect to increase in displacement, said characteristics having an intersection with each other at a displacement from said object equal to the displacement of said reference point.
Claim 5
Dependent Claim
169 words
Apparatus for determining displacement of an object with respect to a reference point, comprising: a light source for providing illumination of said object; a first photosensitive element disposed to receive light directly reflected from said source, and having a first electrical output characteristic which is proportional to displacement from said first photosensitive element to said object; a second photosensitive element disposed to receive light diffusively reflected from said source, and having a second electrical output characteristic which is proportional to displacement between said second photosensitive element and said object and different from said first characteristic; and means for comparing an output from said first photosensitive element with an output from said second photosensitive element to determine the relative displacement of said object with respect to a predetermined reference point, said characteristics each comprising a voltage-displacement relationship in which the voltage decreases with respect to increase in displacement, said characteristics having an intersection with each other at a displacement from said object equal to the displacement of said reference point.
Claim 6
Dependent Claim
33 words
Apparatus according to claim 3 wherein said output of one of said photosensitive elements is adjustable to equalize a voltage representing said first photosensitive element and a voltage representing said second photosensitive element.
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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |