Patent US5067090A successfully refreshed from Google Patents.
EP0115037A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Cathode ray tube display deflection system
Assignee: International Business Machines Corp
•
Filing: 1983-12-21
•
Granted: —
•
Expires: 2003-12-21
Abstract
Abstract A variable format CRT display is driven by a transistor 10 which is turned-off by a synchronising pulse 20 and is turned on when the coil current generated by a diode and capacitor circuit 44 reaches a settable threshold 54. Drift compensation is exercised by a delay mechanism fixed by the synchronising pulse, which sets a latch 22, quenching transistor 25 and allowing capacitor 26 to charge through a variable resistance 46. When the ramp voltage 24 attains the voltage of a second capacitor 27, comparator 18 generates a pulse 30 setting latch 12 and turning off transistor 10. The flyback current 43a is clipped to a pulse 43b which fires transistor 40 to enable a current minor 34, 45 to charge capacitor 27 until the ramp voltage reaches a reference value 29 whereat capacitor 27 discharges and capacitor 26 is discharged. If discharge is not centred on pulse 43b, the charged state of capacitor 27 will vary to tend to maintain centring. Variables 32, 36 and 54 exercise gross control.
Inventors
- 👤 Paul William Bond
- 👤 James Donald Rockrohr
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 18:05
CPC Classifications
H; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/60; H03K4/62; H03K4/64
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
159 words
A cathode ray tube display deflection system responsive to an external.,synchronising signal and including a deflection yoke coil (16), a coil drive (10,44) generating a ramp current in the coil and a drift compensated drive control characterised in that the drive control comprises: (a) first means (42)responsive to the flyback current in the coil for generating a flyback pulse (43b) defining the flyback period; (b) second means (26, 46) generating a ramp voltage during the deflection'"period of the coil ramp current following each synchronising signal (20); (c) third means (27, 34, 40, 45) deriving a measure of the relative durations of the pre- and post- ramp voltage termination portions of the pulse defined flyback period; and (d) fourth means (18) responsive to the second and third means generating a timed control pulse (30) advanced or retarded relative to the preceding control pulse in such a way as to tend to maintain a constant ratio of the flyback pulse portions.
Claim 2
Dependent Claim
159 words
A cathode ray tube display deflection system responsive to an external.,synchronising signal and including a deflection yoke coil (16), a coil drive (10,44) generating a ramp current in the coil and a drift compensated drive control characterised in that the drive control comprises: (a) first means (42)responsive to the flyback current in the coil for generating a flyback pulse (43b) defining the flyback period; (b) second means (26, 46) generating a ramp voltage during the deflection'"period of the coil ramp current following each synchronising signal (20); (c) third means (27, 34, 40, 45) deriving a measure of the relative durations of the pre- and post- ramp voltage termination portions of the pulse defined flyback period; and (d) fourth means (18) responsive to the second and third means generating a timed control pulse (30) advanced or retarded relative to the preceding control pulse in such a way as to tend to maintain a constant ratio of the flyback pulse portions.
Claim 3
Dependent Claim
31 words
A system as claimed in claim 1 wherein the second means includes an externally variable component (46) whereby the centring of the deflection produced by the coil drive can be adjusted.
Claim 4
Independent Claim
41 words
A system as claimed in either preceding claims wherein the third means has an adjustable input (29, 32) whereby the delay between the start of the ramp current generation and the flyback initiation can be adjusted to vary the trace length.
Claim 5
Independent Claim
30 words
A system as claimed in any preceding claim in which the fourth means has an externally adjustable input (54, 14, 12) whereby the centring of the drive can be adjusted.
Claim 6
Independent Claim
82 words
A system as claimed in any preceding claim wherein the coil drive comprises a scan current driver (10), controlled by the fourth means and an inductive "spring" (44) generating flyback drive, on release of the driver, the fourth means including a latch (12) of the kind having a predominant state, established by the control pulses, in which the driver (10) is ineffective, its minor state, in which the driver is effective, being established by attainment of a threshold by the coil current.
Claim 7
Independent Claim
47 words
A system as claimed in any preceding claim in which the third means comprises a capacitance (27), connected to a charging/discharging circuit, enabled for either operation by each flyback pulse and switched, in operation, by a signal (21) which terminates ramp voltage generation by the second means.
Claim 8
Independent Claim
75 words
A system as claimed in any preceding claim wherein the second means comprises a capacitance (26) and a variable reactance 46 connected in series, their common mode being dischargeable through a transistor (25) and defining the ramp voltage as it recharges when the transistor is generated in response to the synchronising signal, the common mode voltage (24) being compared (at 32) with a reference voltage 29 to generate an enabling signal (21) to the transistor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.