US4621240A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Temperature compensated oscillator for raster scanned video display
Assignee: Zenith Electronics LLC
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Filing: 1985-06-28
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Granted: 1986-11-04
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Expires: 2005-06-28
Abstract
Abstract In the horizontal drive of a raster scanned video display, a free running astable multivibrator responsive to a synchronization input signal provides a horizontal output signal to horizontal deflection circuitry for synchronizing the video display's raster scan with the video information presented thereon. The astable multivibrator includes a pair of coupled transistors which are alternately rendered conductive in accordance with the time constant of a respective RC network associated with each transistor. To compensate for the temperature-dependent operation of the transistor pair which causes the multivibrator's operating frequency to increase with increasing temperature, a pair of back-to-back coupled diodes are connected to provide the synchronization input signal to one RC network so as to increase the charge on a capacitor within the network, the time constant of which is similarly increased. The temperature-dependent change in voltage across the diodes compensates for the change in V BE of the transistor with temperature to maintain the time before transistor turn-on constant. A second pair of similarly coupled diodes may be connected to the second RC network to provide temperature compensation for the second transistor.
Inventors
- 👤 Robert J. Alvord
- 👤 Robert Amberg
- 👤 Michael T. Fegan
- 👤 Joseph Kadlec
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:40
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/26; H03K3/28; H03K3/281; H03K3/282; H03K3/2823; H03K3/01; H03K3/011
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
161 words
In a horizontal deflection circuit responsive to a synchronization signal for providing horizontal drive signals to deflection circuitry for horizontally scanning an electron beam across a faceplate of a raster scanned video display in timed relation with video information presented on said video display, a temperature compensated oscillator comprising: first and second timing networks respectively directly and indirectly responsive to the synchronization signal for producing first and second turn-on signals in timed relation with the synchronization signal; first and second temperature-dependent conducting means respectively coupled to said first and second timing networks and alternately rendered conductive in said timed relation with the synchronization signal by said first and second turn-on signals, respectively, for providing horizontal drive signals to the deflection circuitry; and temperature compensating means including temperature responsive bi-directional conducting means coupled to said first timing network for controlling said first turn-on signal wherein the operation of said first conducting means is substantially independent of the operating temperature of the oscillator.
Claim 2
Dependent Claim
161 words
In a horizontal deflection circuit responsive to a synchronization signal for providing horizontal drive signals to deflection circuitry for horizontally scanning an electron beam across a faceplate of a raster scanned video display in timed relation with video information presented on said video display, a temperature compensated oscillator comprising: first and second timing networks respectively directly and indirectly responsive to the synchronization signal for producing first and second turn-on signals in timed relation with the synchronization signal; first and second temperature-dependent conducting means respectively coupled to said first and second timing networks and alternately rendered conductive in said timed relation with the synchronization signal by said first and second turn-on signals, respectively, for providing horizontal drive signals to the deflection circuitry; and temperature compensating means including temperature responsive bi-directional conducting means coupled to said first timing network for controlling said first turn-on signal wherein the operation of said first conducting means is substantially independent of the operating temperature of the oscillator.
Claim 3
Dependent Claim
40 words
The temperature compensated oscillator of claim 1 wherein each of said timing networks includes at least one resistor and at least one capacitor charged by the synchronization signal so as to generate a respective turn-on signal upon the discharge thereof.
Claim 4
Dependent Claim
35 words
The temperature compensated oscillator of claim 2 wherein a respective RC time constant of each timing network establishes the turn-on time of the respective conducting means coupled thereto following receipt of the respective turn-on signal.
Claim 5
Dependent Claim
29 words
The temperature compensated oscillator of claim 1 wherein each conducting means includes a respective transistor and wherein the turn-on signal level of each transistor decreases with increasing operating temperature.
Claim 6
Dependent Claim
55 words
The temperature compensated oscillator of claim 4 wherein said temperature compensating means increases the time between receipt of a synchronization signal and the generation of said first turn-on signal by said first timing network with increasing operating temperatures in compensating for the decrease in turn-on signal level of the transistor in said first conducting means.
Claim 7
Dependent Claim
48 words
The temperature compensated oscillator of claim 5 wherein each timing network includes a respective RC circuit having a characteristic time constant and wherein said temperature compensating means regulates the discharging of the RC circuit of said first timing network in controlling the timing of said first turn-on signal.
Claim 8
Dependent Claim
54 words
The temperature compensated oscillator of claim 6 wherein said temperature compensating means increases the charge across a capacitor in the RC network of said first timing network for delaying the occurrence of said first turn-on signal in maintaining the turn-on of the transistor in said first conducting means substantially unchanged with increasing operating temperatures.
Claim 9
Dependent Claim
33 words
The temperature compensated oscillator of claim 7 wherein said temperature responsive bi-directional conducting means provides said increased charge across said capacitor with increasing operating temperatures and allows for the discharge of said capacitor.
Claim 10
Dependent Claim
23 words
The temperature compensated oscillator of claim 1 wherein said temperature compensating means includes a pair of back-to-back coupled diodes connected to said capacitor.
Claim 11
Dependent Claim
61 words
The temperature compensated oscillator of claim 1 wherein said oscillator is a free-running astable multivibrator and wherein said temperature compensating means is further coupled to said second timing network for controlling said first and second turn-on signals and the operation of said first and second conducting means for maintaining the operation of said free-running astable multivibrator independent of its operating temperature.
Claim 12
Dependent Claim
73 words
The temperature compensated oscillator of claim 10 wherein each of said timing networks includes a respective RC circuit and each of said conducting means includes a respective transistor and wherein said temperature compensating means includes first and second pairs of back-to-back coupled diodes connected to a capacitor in said respective RC circuit for increasing the charge thereon with increasing operating temperatures and maintaining the turn-on of said transistors unchanged with increasing operating temperatures.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1989-11-03 | 1990-05-05 | 1990-11-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-11-03 | 1994-05-05 | 1994-11-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-11-03 | 1998-05-05 | 1998-11-04 | $7700.00 | Window Closed / Lapsed |