US3590152A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Narrow bandwidth picture transmission apparatus
Assignee: VIDCOM ELECTRONICS Inc
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Filing: 1968-11-13
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Granted: 1971-06-29
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Expires: 1988-11-13
Abstract
Abstract Slow-scan video apparatus for transmitting video information through a narrow band transmission path such as a telephone line, comprises a transmitter and receiver, the transmitter including a photomultiplier responsive to light from the face of a cathoderay tube reflected from the image to be transmitted, an audio frequency oscillator the output of which is modulated by the video output from the photomultiplier tube, and means for coupling the modulated audio frequency output to the narrow band transmission line. The receiver includes demodulating means which reconstructs the video information and applies it to the cathode of an electron discharge tube to create the transmitted image on the face of the receiver tube, where it is stored, for example, by photography. The transmitted includes a shading control circuit to assure an optical input to the photomultiplier tube proportional to the reflectance of the picture being transmitted over the entire picture area, a brightness control circuit which senses the whitest portion of the image to be transmitted and correlates the modulator output to this whitest level, and a control mechanism which disables the transmitter apparatus when the receiver is not in condition to receive a transmitted image. In addition, the system includes a gamma correction circuit wherein the image is transmitted through the audio frequency transmission path in such a way that noise introduced into the received picture by the transmission path will be subjectively equal in all grey levels, and to make the grey scale rendition of the received picture subjectively similar to that of the transmitted picture.
Inventors
- 👤 Copthorne Mcdonald
- 👤 C Robert Fine
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 09:48
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/407; H04N1/4072; H04N1/401; H04N5/00; H04N5/14; H04N5/20; H04N5/202
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
229 words
Slow-scan video apparatus comprising a transmitter and receiver connected by a narrow band transmission path, said transmitter comprising a cathode-ray tube, vertical and horizontal sweep means for producing voltages which cause an electron beam to be scanned across the face of said tube, said beam being converted into a light beam on said tube face, said tube including means for varying the intensity of said light beam, means for focusing said light beam on the picture to be transmitted, photosensitive means responsive to the reflection of said light beam from said picture for producing a current which is a function of the light intensity of said reflected beam, an audio frequency oscillator, means responsive to the current from said photosensitive means for modulating the output of said audio frequency oscillator, means responsive to the voltages produced by said sweep means for generating a control voltage having an amplitude related to the position of said optical beam relative to said photosensitive means, said control voltage being coupled to said intensity varying means to provide a substantially uniform light input to said photosensitive means when said optical beam is scanning a uniform optical field, and means coupling the modulated output of said oscillator to said narrow band transmission path, said receiver comprising means for demodulating said modulated output applied to said transmission path, and means for reproducing and storing said image.
Claim 2
Dependent Claim
229 words
Slow-scan video apparatus comprising a transmitter and receiver connected by a narrow band transmission path, said transmitter comprising a cathode-ray tube, vertical and horizontal sweep means for producing voltages which cause an electron beam to be scanned across the face of said tube, said beam being converted into a light beam on said tube face, said tube including means for varying the intensity of said light beam, means for focusing said light beam on the picture to be transmitted, photosensitive means responsive to the reflection of said light beam from said picture for producing a current which is a function of the light intensity of said reflected beam, an audio frequency oscillator, means responsive to the current from said photosensitive means for modulating the output of said audio frequency oscillator, means responsive to the voltages produced by said sweep means for generating a control voltage having an amplitude related to the position of said optical beam relative to said photosensitive means, said control voltage being coupled to said intensity varying means to provide a substantially uniform light input to said photosensitive means when said optical beam is scanning a uniform optical field, and means coupling the modulated output of said oscillator to said narrow band transmission path, said receiver comprising means for demodulating said modulated output applied to said transmission path, and means for reproducing and storing said image.
Claim 3
Dependent Claim
61 words
Slow-scan video apparatus according to claim 1, including means for producing a voltage which is a logarithmic function of the output current of said photomultiplier, and means for adjusting the level of the output of said demodulating means so that the image stored in said reproducing and storing means has essentially the same gray scale as the image to be transmitted.
Claim 4
Dependent Claim
81 words
Slow-scan video apparatus according to claim 1, including means for prescanning said image prior to picture transmission, means for sensing when the level of the output of said photosensitive means exceeds a preselected level during said prescanning, and means responsive to said level sensing means for causing said intensity varying means to adjust the intensity of said beams so that said modulating means produces a predetermined modulated output for the highest output level of said photosensitive means detected during said prescanning.
Claim 5
Dependent Claim
61 words
Slow-scan video apparatus according to claim 3, including means for producing a voltage which is a logarithmic function of the output current of said photomultiplier, and means for adjusting the level of the output of said demodulating means so that the image stored in said reproducing and storing means has essentially the same gray scale as the image to be transmitted.
Claim 6
Dependent Claim
46 words
Slow-scan video apparatus according to claim 1, including means for coupling a ready signal from said receiver to said transmitter through said transmission path when said receiver is ready to receive information signals from said transmitter, said transmitter including indicator means responsive to said ready signal.
Claim 7
Dependent Claim
21 words
Slow-scan video apparatus according to claim 5, wherein said means for reproducing and storing comprises a display tube and photographic camera.
Claim 8
Dependent Claim
229 words
Slow-scan video apparatus comprising transmitter and receiver connected by a narrow band transmission path, said transmitter comprising a cathode-ray tube, vertical and horizontal sweep means for scanning an electron beam across the face of said tube, said beam being converted into a light bEam on said tube face, said tube including means for varying the intensity of said light beam, means for focusing said light beam on the picture to be transmitted, photosensitive means responsive to the reflection of said light beam from said picture for producing a current which is a function of the light intensity of said reflected beam, an oscillator, means responsive to the current from said photosensitive means for modulating the output of said oscillator, means for prescanning said image prior to picture transmission, means for sensing when the level of the output of said photosensitive means exceeds a preselected level during said prescanning, and means responsive to said level sensing means for causing said intensity varying means to adjust the intensity of said beams so that said modulating means produces a predetermined modulated output for the highest output level of said photosensitive means detected during said prescanning, and means coupling the modulated output of said oscillator to said narrow band transmission path, said receiver comprising means for demodulating said modulated output applied to said transmission path, and means for reproducing and storing said image.
Claim 9
Dependent Claim
229 words
Slow-scan video apparatus comprising transmitter and receiver connected by a narrow band transmission path, said transmitter comprising a cathode-ray tube, vertical and horizontal sweep means for scanning an electron beam across the face of said tube, said beam being converted into a light bEam on said tube face, said tube including means for varying the intensity of said light beam, means for focusing said light beam on the picture to be transmitted, photosensitive means responsive to the reflection of said light beam from said picture for producing a current which is a function of the light intensity of said reflected beam, an oscillator, means responsive to the current from said photosensitive means for modulating the output of said oscillator, means for prescanning said image prior to picture transmission, means for sensing when the level of the output of said photosensitive means exceeds a preselected level during said prescanning, and means responsive to said level sensing means for causing said intensity varying means to adjust the intensity of said beams so that said modulating means produces a predetermined modulated output for the highest output level of said photosensitive means detected during said prescanning, and means coupling the modulated output of said oscillator to said narrow band transmission path, said receiver comprising means for demodulating said modulated output applied to said transmission path, and means for reproducing and storing said image.
Claim 10
Dependent Claim
61 words
Slow-scan video apparatus according to claim 7, including means for producing a voltage which is a logarithmic function of the output current of said photomultiplier, and means for adjusting the level of the output of said demodulating means so that the image stored in said reproducing and storing means has essentially the same gray scale as the image to be transmitted.
Claim 11
Dependent Claim
46 words
Slow-scan video apparatus according to claim 7, including means for coupling a ready signal from said receiver to said transmitter through said transmission path when said receiver is ready to receive information signals from said transmitter, said transmitter including indicator means responsive to said ready signal.
Claim 12
Dependent Claim
21 words
Slow-scan video apparatus according to claim 9, wherein said means for reproducing and storing comprises a display tube and photographic camera.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-06-28 | 1974-12-28 | 1975-06-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-28 | 1978-12-28 | 1979-06-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-28 | 1982-12-28 | 1983-06-29 | $7700.00 | Window Closed / Lapsed |