Patent US4598235A successfully refreshed from Google Patents.
US4598235A
Expired / Lapsed
US
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Method and apparatus for eliminating lag in photoelectric tubes
Assignee: Ampex Corp
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Filing: 1984-03-27
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Granted: 1986-07-01
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Expires: 2004-03-27
Abstract
Abstract For each magnitude of charge stored on a section of a target of a photoelectric tube due to the action of incident light thereon, there is a specific value of cathode voltage which ensures the discharge of the section in one pass of the scanning beam. It follows that if the cathode receives a voltage whose instantaneous value is proportional to the magnitude of the charge stored on the corresponding portion of the target, the complete discharge of the target is effected in one pass of the scanning electron beam. Since the output voltage of a camera preamplifier at any instant is directly related to the magnitude of the charge stored on the corresponding portion of the target of the same tube or a different tube viewing the same scene, the preamplifier output voltage herein is selectively applied to the tube cathode, preferably with an appropriate transfer function, whereby lag in the tube is eliminated.
Inventors
- 👤 John O. Ryan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 10:17
CPC Classifications
H; H04; H04N; H04N23/00; H04N23/40
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
182 words
A circuit for eliminating lag in a photoelectric tube having a cathode, a target, and an electron beam generated by the cathode for scanning an image on the target and for generating a video output signal, said circuit including a feedback loop for supplying an electrical voltage back to the cathode whose value at any instant is proportional to the intensity of the image on the corresponding portion of the target scanned by the electron beam, which voltage has a selected non-linear characteristic corresponding to the lag characteristic of the tube, comprising: auxiliary tube means integral with the feedback loop and having a cathode coupled directly to ground and a target disposed to also retain the same image as scanned by said photoelectric tube, wherein the auxiliary tube means and feedback loop provide the electrical voltage of selected non-linear characteristic; said photoelectric tube including an output terminal coupled to the target thereof for supplying said video output signal; and said target of the auxiliary tube means is coupled via the integral feedback loop back to only the cathode of the photoelectric tube.
Claim 2
Dependent Claim
182 words
A circuit for eliminating lag in a photoelectric tube having a cathode, a target, and an electron beam generated by the cathode for scanning an image on the target and for generating a video output signal, said circuit including a feedback loop for supplying an electrical voltage back to the cathode whose value at any instant is proportional to the intensity of the image on the corresponding portion of the target scanned by the electron beam, which voltage has a selected non-linear characteristic corresponding to the lag characteristic of the tube, comprising: auxiliary tube means integral with the feedback loop and having a cathode coupled directly to ground and a target disposed to also retain the same image as scanned by said photoelectric tube, wherein the auxiliary tube means and feedback loop provide the electrical voltage of selected non-linear characteristic; said photoelectric tube including an output terminal coupled to the target thereof for supplying said video output signal; and said target of the auxiliary tube means is coupled via the integral feedback loop back to only the cathode of the photoelectric tube.
Claim 3
Dependent Claim
28 words
The circuit of claim 1 wherein the auxiliary tube means receives a selected fraction of the light corresponding to the image which is scanned by the photoelectric tube.
Claim 4
Dependent Claim
94 words
The circuit of claim 1 further including second and third photoelectric tubes, each having respective second and third cathodes, targets and electron beams and disposed to retain the same image on the targets thereof that is scanned by the first photoelectric tube, and each having respective second and third video output terminals coupled from respective targets; said feedback loop for generating the electrical voltage of non-linear characteristic is operatively coupled from the target of the auxiliary tube means back to only the respective second and third cathodes of the second and third photoelectric tubes.
Claim 5
Dependent Claim
142 words
A circuit for eliminating lag in photoelectric tubes having a cathode and a target for retaining charges indicative of an image, and including feedback loop means for supplying an instantaneous feedback voltage proportional to the magnitude of the charge stored on a corresponding portion of the targets, wherein the feedback loop means further provides a preselected transfer function corresponding to the lag characteristic of the tubes, comprising: red, green and blue photoelectric tubes for generating red, green and blue video signals corresponding to the image via respective red, green and blue targets; said feedback loop means being coupled from the target of the green photoelectric tube back to the cathodes of the red and blue photoelectric tubes to supply the instantaneous feedback voltage to the red and blue cathodes; and wherein said green photoelectric tube has its cathode coupled directly to ground.
Claim 6
Dependent Claim
142 words
A circuit for eliminating lag in photoelectric tubes having a cathode and a target for retaining charges indicative of an image, and including feedback loop means for supplying an instantaneous feedback voltage proportional to the magnitude of the charge stored on a corresponding portion of the targets, wherein the feedback loop means further provides a preselected transfer function corresponding to the lag characteristic of the tubes, comprising: red, green and blue photoelectric tubes for generating red, green and blue video signals corresponding to the image via respective red, green and blue targets; said feedback loop means being coupled from the target of the green photoelectric tube back to the cathodes of the red and blue photoelectric tubes to supply the instantaneous feedback voltage to the red and blue cathodes; and wherein said green photoelectric tube has its cathode coupled directly to ground.
Claim 7
Independent Claim
146 words
A method for eliminating lag in a photoelectric tube having a target, a cathode and a scanning electron beam, and including generating a feedback voltage whose value at any instant is proportional to the intensity of light from an image which is supplied to the target scanned by the electron beam, which feedback voltage has a selected non-linear characteristic corresponding to the lag characteristic of the photoelectric tube, comprising: separating a portion of the light from the image into a second light path; directing the second path of light to a target of an auxiliary tube means to generate the feedback voltage; conforming the feedback voltage to define the selected non-linear characteristic; supplying the conformed feedback voltage back to only the cathode of the photoelectric tube; grounding the cathode of the auxiliary tube; and supplying a video output signal via the target of the photoelectric tube.
Claim 8
Independent Claim
146 words
A method for eliminating lag in a photoelectric tube having a target, a cathode and a scanning electron beam, and including generating a feedback voltage whose value at any instant is proportional to the intensity of light from an image which is supplied to the target scanned by the electron beam, which feedback voltage has a selected non-linear characteristic corresponding to the lag characteristic of the photoelectric tube, comprising: separating a portion of the light from the image into a second light path; directing the second path of light to a target of an auxiliary tube means to generate the feedback voltage; conforming the feedback voltage to define the selected non-linear characteristic; supplying the conformed feedback voltage back to only the cathode of the photoelectric tube; grounding the cathode of the auxiliary tube; and supplying a video output signal via the target of the photoelectric tube.
References Cited (Backward Citations)
US3534168A
Cited
US3715490A
Cited
USPTO Annuity & Maintenance Windows
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|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-06-30 | 1989-12-30 | 1990-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-06-30 | 1993-12-30 | 1994-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-06-30 | 1997-12-30 | 1998-07-01 | $7700.00 | Window Closed / Lapsed |