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EP0138245A1
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Apparatus for reading a disc-shaped record carrier
Assignee: Koninklijke Philips NV
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Filing: 1984-08-28
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Granted: —
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Expires: 2004-08-28
Abstract
Abstract The invention relates to a video-disc player in which by controlling a pivotal mirror rapid jumps over a large number of tracks can be made substantially within the field-blanking interval. In order to minimize the picture disturbance the jump is always started at the instant at which the duration of the remaining period until just before the address code within the next field blanking interval is equal to the anticipated duration of the jump to be performed, in particular by measuring the time which has elapsed since the previous read-out of an address code.
Inventors
- 👤 Robertus Wilhelmus Catharina Groen
- 👤 Cornelis Adrianus Maria De Jonge
- 👤 Lawrence Mark Schwartz
- 👤 Johannes Christiaan Van Lier
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-06 08:32
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/08; G11B7/085; G11B7/08505; G11B7/08517; G11B7/08529; G11B7/08535; G11B7/08547; G11B7/08564; H; H04; H04N; H04N5/00; H04N5/76; H04N5/7605; Y; Y10; Y10S; Y10S358/00; Y10S358/907
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
320 words
Apparatus for reading a disc-shaped record carrier in which video signals are recorded in substantially spiral tracks in such a way that corresponding picture elements of consecutive pictures are situated at substantially the same circumferential position on said record carrier, an address code being contained in at least one of the two fields of each video picture in said video signals at a predetermined position in the field blanking interval after the field-synchronizing pulse, which apparatus comprises: an optical system for aiming a light beam at the record carrier, said light beam being modulated by the record carrier, and for converting said modulated light beam into an electric signal, a converter for converting said electric signal into a radial tracking-error signal which corresponds to the radial position of the landing spot of the light beam relative to a desired track, positioning means for controlling the position landing spot of the light beam as a function of the radial tracking error signal, a jump-signal generator for generating a control signal for causing the landing spot of the light beam to be shifted over a predetermined distance in response to a jump signal, and means for applying said control signal to the positioning means during said jump, characterized by means for generating a first signal which is a continuous measure of the duration of the period of time up to a reference point in the field-blanking interval which point precedes said address code, means for generating, a second signal under command of the jump signal, which second signal is a measure of the anticipated duration of the jump to be performed in response to said command, and means for continuously comparing said first and said second signal and, in relation to the instant at which the two durations coincide, generating a starting signal for the jump-signal generator at least if said instant appears prior to the field-synchronizing pulse preceding said address code.
Claim 2
Dependent Claim
320 words
Apparatus for reading a disc-shaped record carrier in which video signals are recorded in substantially spiral tracks in such a way that corresponding picture elements of consecutive pictures are situated at substantially the same circumferential position on said record carrier, an address code being contained in at least one of the two fields of each video picture in said video signals at a predetermined position in the field blanking interval after the field-synchronizing pulse, which apparatus comprises: an optical system for aiming a light beam at the record carrier, said light beam being modulated by the record carrier, and for converting said modulated light beam into an electric signal, a converter for converting said electric signal into a radial tracking-error signal which corresponds to the radial position of the landing spot of the light beam relative to a desired track, positioning means for controlling the position landing spot of the light beam as a function of the radial tracking error signal, a jump-signal generator for generating a control signal for causing the landing spot of the light beam to be shifted over a predetermined distance in response to a jump signal, and means for applying said control signal to the positioning means during said jump, characterized by means for generating a first signal which is a continuous measure of the duration of the period of time up to a reference point in the field-blanking interval which point precedes said address code, means for generating, a second signal under command of the jump signal, which second signal is a measure of the anticipated duration of the jump to be performed in response to said command, and means for continuously comparing said first and said second signal and, in relation to the instant at which the two durations coincide, generating a starting signal for the jump-signal generator at least if said instant appears prior to the field-synchronizing pulse preceding said address code.
Claim 3
Dependent Claim
30 words
An apparatus as claimed in Claim 1, characterized in that the means for generating the first signal comprise counting means which are started each time that an address code appears.
References Cited (Backward Citations)
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