GB729621A - Improvements in or relating to circuits for levelling datum signals interspersed in electric signals, for example television signals - Google Patents
Improvements in or relating to circuits for levelling datum signals interspersed in electric signals, for example television signalsInfo
- Publication number
- GB729621A GB729621A GB1299053A GB1299053A GB729621A GB 729621 A GB729621 A GB 729621A GB 1299053 A GB1299053 A GB 1299053A GB 1299053 A GB1299053 A GB 1299053A GB 729621 A GB729621 A GB 729621A
- Authority
- GB
- United Kingdom
- Prior art keywords
- signals
- datum
- circuit
- level
- reference potential
- 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
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
- H04N5/18—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit
- H04N5/185—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level by means of "clamp" circuit operated by switching circuit for the black level
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/14—Picture signal circuitry for video frequency region
- H04N5/16—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
- H04N5/165—Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level to maintain the black level constant
Landscapes
- Engineering & Computer Science (AREA)
- Multimedia (AREA)
- Signal Processing (AREA)
- Nuclear Medicine (AREA)
- Processing Of Color Television Signals (AREA)
- Color Television Image Signal Generators (AREA)
- Protection Of Plants (AREA)
Abstract
729,621. Television. ELECTRIC & MUSICAL INDUSTRIES, Ltd. April 2, 1951 [April 1, 1950], No. 12990/53. Divided out of 729,541. Class 40 (3). A circuit for levelling datum signals interspersed with other signals for example, television signals, comprises means for clamping said signals at a reference potential at relatively frequent intervals, means for observing the level of other datum signals at less frequent intervals and for storing a signal representing said level and means for adjusting said reference potential in response to variations in said stored level. The invention is described as applied to signals derived from the film scanner described in Specification 729,541. The signals, Fig. 2, contain datum portions 4 corresponding to blacker-than-black derived when the scanning light spot is extinguished at the end of each line, and other datum portion 5 corresponding to true black derived by scanning the bar separating adjacent film frames. The signals are applied through a condenser 1 to the input of a gamma correction circuit 2 of the type described in Specification 702,325, [Group XL (c)], and are clamped to a reference potential by means of circuit 10 of the type described in Specification 449,242 which is rendered operative once in every line by pulses 11 timed to coincide with the intervals 4. At the output of circuit 2, a bi-directionally conductive switch 6 is brought into operation once per frame during the intervals. 5 by pulses 8 and allows a condenser 7 to acquire a potential representative of the level of the other datum portion. This potential is then applied through D.C. amplifier 9 to adjust the reference potential in circuit 10. A limiter circuit 12 or 13 may be included to limit the amplitude of signals 4 in excess of true black. The rectifier shown in Fig. 3 of Specification 702,325, [Group XL (c)], may be arranged to function for this purpose.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB820550A GB729541A (en) | 1950-04-01 | 1950-04-01 | Improvements in or relating to television film scanners |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB729621A true GB729621A (en) | 1955-05-11 |
Family
ID=9847885
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1299053A Expired GB729621A (en) | 1950-04-01 | 1950-04-01 | Improvements in or relating to circuits for levelling datum signals interspersed in electric signals, for example television signals |
| GB820550A Expired GB729541A (en) | 1950-04-01 | 1950-04-01 | Improvements in or relating to television film scanners |
Family Applications After (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB820550A Expired GB729541A (en) | 1950-04-01 | 1950-04-01 | Improvements in or relating to television film scanners |
Country Status (1)
| Country | Link |
|---|---|
| GB (2) | GB729621A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB770457A (en) * | 1953-06-09 | 1957-03-20 | Fernseh Gmbh | Process for transmission of pictures by television |
-
1950
- 1950-04-01 GB GB1299053A patent/GB729621A/en not_active Expired
- 1950-04-01 GB GB820550A patent/GB729541A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB729541A (en) | 1955-05-11 |
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