GB1057477A - Picture control circuit for a television receiver - Google Patents
Picture control circuit for a television receiverInfo
- Publication number
- GB1057477A GB1057477A GB3369264A GB3369264A GB1057477A GB 1057477 A GB1057477 A GB 1057477A GB 3369264 A GB3369264 A GB 3369264A GB 3369264 A GB3369264 A GB 3369264A GB 1057477 A GB1057477 A GB 1057477A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cathode
- video signal
- tube
- voltage
- fraction
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/44—Receiver circuitry for the reception of television signals according to analogue transmission standards
- H04N5/57—Control of contrast or brightness
- H04N5/59—Control of contrast or brightness in dependence upon beam current of cathode ray tube
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Television Receiver Circuits (AREA)
- Picture Signal Circuits (AREA)
Abstract
1,057,477. Controlling television picture signals. HAZELTINE CORPORATION. Aug 18, 1964 [Oct. 24, 1963], No. 33692/64. Heading H3Q. In a television receiver keyed A.G.C. system with additional means for stabilizing the black level and limiting beam current in scenes of high average brightness as in Specifications 1,057,474 and 1,057,475, the video signal is applied to the cathode-ray tube and the A.G.C. circuit via networks having different A.C. and D.C. gains, and the A.G.C. cirucit is also supplied (at a second input) with a fraction of the D.C. component of the video signal, and (at the first input) with a fraction of the D.C. component of the voltage at the cathode of the cathode-ray tube. In Fig. 1 the output from the video amplifier 13 is passed to the cathode of the picture tube 15 via an RC network 23 as in Specification 1,057,475, but the sync-tip gated A.G.C. tube 28 of that Specification is fed by a further RC network 30. In addition, the beam current flowing through resistor 24 develops a voltage representing the average value of the video signal and this is applied to the cathode ef the A.G.C. tube via resistor 35. The A.C./ D.C. transmission ratios of the two networks 23, 30 are so chosen, in conjunction with any unequal transmission of A.C. and D.C. through the video amplifier, that the gain of the receiver is controlled in accordance with the average value of the video signal and at the same time the black level is preserved. The circuit can also be used with back-porch gated A.G.C. (Fig. 2, not shown). Contrast control can be applied by. injecting a variable voltage at point 27 in Fig. 1 (Fig. 3, not shown).
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US318608A US3316351A (en) | 1963-09-18 | 1963-10-24 | Black level control circuit for a television receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB1057477A true GB1057477A (en) | 1967-02-01 |
Family
ID=23238873
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB3369264A Expired GB1057477A (en) | 1963-10-24 | 1964-08-18 | Picture control circuit for a television receiver |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB1057477A (en) |
-
1964
- 1964-08-18 GB GB3369264A patent/GB1057477A/en not_active Expired
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