GB968719A - Improvements in control circuits of cathode ray tubes - Google Patents
Improvements in control circuits of cathode ray tubesInfo
- Publication number
- GB968719A GB968719A GB4306161A GB4306161A GB968719A GB 968719 A GB968719 A GB 968719A GB 4306161 A GB4306161 A GB 4306161A GB 4306161 A GB4306161 A GB 4306161A GB 968719 A GB968719 A GB 968719A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cathode
- diode
- capacitor
- dec
- tube
- 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
- H04N3/00—Scanning details of television systems; Combination thereof with generation of supply voltages
- H04N3/10—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical
- H04N3/16—Scanning details of television systems; Combination thereof with generation of supply voltages by means not exclusively optical-mechanical by deflecting electron beam in cathode-ray tube, e.g. scanning corrections
- H04N3/20—Prevention of damage to cathode-ray tubes in the event of failure of scanning
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Details Of Television Scanning (AREA)
Abstract
968,719. Cathode-ray tube protection circuits. COMPAGNIE FRANCAISE THOMSONHOUSTON. Dec. 1, 1961 [Dec. 1, 1960], No. 43061/61. Heading H4T. Damage to the screen of a television picture tube when the receiver is switched off, due to the thermal inertia of the cathode, the charge on the E.H.T. smoothing capacitor and the cessation of scanning, is prevented by means of a threshold device comprising a Zener diode 5, which, in the embodiment of Fig. 1, is connected between the final video amplifier and the cathode 6 of the picture tube 8 such that the cathode current of the latter flows through diode 5 in the reverse direction or, in the embodiment of Fig. 2, is connected in opposition with a conventional diode 12 such that the negative bias (charge on capacitor 4) on the control grid 7, on switching off, can only discharge through the Zener diode 5 in the reverse direction. An advantage of the latter embodiment over known arrangements in which a protective bias is maintained on the control electrode of the tube. is that the resistor 14 and potentiometer 15 may have low values so that the circuit has a small time constant and brightness adjustment is therefore not affected by the delay inherent in the known arrangements which have large time constants. In the embodiment of Fig. 1, the diode is shunted by a capacitor 4 which bypasses it for video signal frequencies.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR845550A FR1281404A (en) | 1960-12-01 | 1960-12-01 | Improvements to cathode ray tube monitoring and control circuits |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB968719A true GB968719A (en) | 1964-09-02 |
Family
ID=8743802
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB4306161A Expired GB968719A (en) | 1960-12-01 | 1961-12-01 | Improvements in control circuits of cathode ray tubes |
Country Status (2)
| Country | Link |
|---|---|
| FR (1) | FR1281404A (en) |
| GB (1) | GB968719A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3629645A (en) * | 1969-08-19 | 1971-12-21 | Sylvania Electric Prod | Television receiver protective system for preventing screen burn |
| JPS5040903Y1 (en) * | 1970-12-17 | 1975-11-21 | ||
| US4390817A (en) * | 1981-02-27 | 1983-06-28 | Zenith Radio Corporation | Integratable CRT spot cut-off network |
-
1960
- 1960-12-01 FR FR845550A patent/FR1281404A/en not_active Expired
-
1961
- 1961-12-01 GB GB4306161A patent/GB968719A/en not_active Expired
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3629645A (en) * | 1969-08-19 | 1971-12-21 | Sylvania Electric Prod | Television receiver protective system for preventing screen burn |
| JPS5040903Y1 (en) * | 1970-12-17 | 1975-11-21 | ||
| US4390817A (en) * | 1981-02-27 | 1983-06-28 | Zenith Radio Corporation | Integratable CRT spot cut-off network |
Also Published As
| Publication number | Publication date |
|---|---|
| FR1281404A (en) | 1962-01-12 |
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