§
Luxuse
Patent Intelligence
Sign In
← Back to Patent Explorer
EP0051092A1 Expired / Lapsed EP ⏱️ 0.0 years remaining

Cathode ray tube drive circuitry

Assignee: International Business Machines Corp
•
Filing: 1980-10-31
•
Granted: —
•
Expires: 2000-10-31
📄 Original PDF 🌐 Google Patents 🔄 Sync Now

Abstract

Abstract Cathode ray tube drive circuitry in which non-linearity of the line scan is corrected by varying the frequency of the pel clock oscillator in accordance with anticipated variations in scanning speed. Predetermined speed corrections are stored in digital store 23 and, by means of digital to analogue converter 24 and integrator 25, are applied to the control input of a voltage controlled oscillator 13. Synchronization of the pel clock with the X-deflection waveform is effected by means of a parallel phase-locked loop comprising counter 15, sample and hold 18, amplifier 20 and low pass filter 21. Preferably a sinusoidal waveform is applied to the X-deflection coil in such a manner as to have a bidirectional raster scan, the X-deflection coil forming part of a tuned circuit of the sinusoidal waveform generator.

Inventors

  • 👤 Ian David Judd

Bibliographic Details

Application Number —
Jurisdiction EP
Data Source google_patents
Last Synchronized 2026-10-26 05:21
CPC Classifications
G; G09; G09G; G09G1/00; G09G1/04; H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/22; H04N3/23; H04N3/233; H04N3/2335

Claims Analysis

Total Claims: 6
Claim 1
Independent Claim 139 words
Cathode ray tube drive circuitry comprising means for tracing a raster on the screen including a deflection yoke which is arranged to operate in co-operation with deflection signal generator means so as to cause the electron beam repetitively to trace a line across the screen, and means for generating pel clock pulses each defining an interval during which the intensity of the electron beam is modulated in accordance with the required image, characterised in that said circuitry comprises a variable frequency oscillator for producing said pel clock pulses, a digital store containing representations indicative of anticipated varations in scanning speed at certain points of the scanned line, and means for varying the frequency of the oscillator in accordance with the stored representations thereby to correct for anticipated speed variations in the scanning speed by slowing or speeding the oscillator.
Claim 2
Dependent Claim 139 words
Cathode ray tube drive circuitry comprising means for tracing a raster on the screen including a deflection yoke which is arranged to operate in co-operation with deflection signal generator means so as to cause the electron beam repetitively to trace a line across the screen, and means for generating pel clock pulses each defining an interval during which the intensity of the electron beam is modulated in accordance with the required image, characterised in that said circuitry comprises a variable frequency oscillator for producing said pel clock pulses, a digital store containing representations indicative of anticipated varations in scanning speed at certain points of the scanned line, and means for varying the frequency of the oscillator in accordance with the stored representations thereby to correct for anticipated speed variations in the scanning speed by slowing or speeding the oscillator.
Claim 3
Dependent Claim 26 words
Drive circuitry as claimed in claim 1, characterised in that said representations are stored in a digital store in the form of a read only store.
Claim 4
Dependent Claim 34 words
Drive circuitry as claimed in any preceding claim, characterised in that said oscillator is a voltage controlled oscillator connected to receive a signal indicative of the actual horizontal scanning speed of the electron spot.
Claim 5
Dependent Claim 40 words
Drive circuitry as claimed in any preceding claim, characterised in that said deflection signal generator means operates to generate a sinusoidal deflection waveform and includes a tuned circuit comprising said yoke, said pel clock being synchronized with said tuned circuit.
Claim 6
Dependent Claim 24 words
Drive circuitry as claimed in claim 4, wherein the deflection signal generator means operates to trace successive lines in opposite directions across the screen.

References Cited (Backward Citations)

US3740608A Cited
US3809947A Cited
US4099092A Cited

USPTO Annuity & Maintenance Windows

Maintenance schedule is calculated for granted US utility patents.

Assigned Categories & Tags

No categories assigned to this patent yet.

Assign Category Tag