US3629686A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Voltage supply apparatus for applying a direct current to a periodically varying load
Assignee: US Philips Corp
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Filing: 1970-04-13
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Granted: 1971-12-21
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Expires: 1990-04-13
Abstract
Abstract A voltage supply apparatus for feeding a periodically varying load provided with a safety circuit wherein a rectified voltage originating from the mains is converted into an output direct voltage by means of a chopper. The switching frequency of the chopper is at least equal to that of the load. The apparatus comprises measuring means by which the chopper is stopped in case of overload, while a smoothing capacitor having a comparatively low capacitance is arranged parallel to the load. After an overload the output voltage is slowly built up. For this purpose the ratio between the active period of the chopper and the period of the switching frequency must become small ( about 0.1). This is achieved by using a thyristor as a pulse duration modulator and by having a capacitor of high value shunt a reference voltage element in the comparison circuit of the chopper. The coil of the chopper constitutes the primary winding of a transformer secondary windings of which drive diodes which conduct simultaneously with the efficiency diode of the chopper so as to generate further direct voltages. In a preferred embodiment the apparatus feeds the line deflection circuit of a picture display device wherein the switching frequency is the line frequency and wherein the output voltage can be modulated by a parabola voltage of field frequency for the purpose of correcting the East-Westpincushion distortion.
Inventors
- 👤 Wilhelmus Theodor Hetterscheid
- 👤 Gerrit Pieter Johannes Schaik
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 23:37
CPC Classifications
H; H04; H04N; H04N3/00; H04N3/10; H04N3/16; H04N3/18; H04N3/185; H02; H02H; H02H7/00; H02H7/10; H02H7/12; H02H7/1213; H02M; H02M3/00; H02M3/02; H02M3/04; H02M3/10; H02M3/145; H02M3/155; H02M3/156; H02M3/22; H02M3/24; H02M3/28; H02M3/325; H02M3/335; H02M3/33507; H02M3/33523; H03; H03K; H03K4/00; H03K4/06; H03K4/08; H03K4/48; H03K4/60; H03K4/62; H03K4/64; H04N3/22; H04N3/23; H04N3/233
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
161 words
A circuit for supplying an output voltage to a periodically varying load of a television line deflecTion oscillator from a power main, said circuit comprising means for rectifying the power main voltage, whereby a voltage having a ripple component is produced; a switch coupled between said rectifying means and the load; means coupled to said switch for generating a periodic pulse switching voltage having a frequency f equal to nj1, wherein n equals an interger, and f1 equals the television line frequency; means for measuring the load current; safety means coupled to said measuring means for blocking said switch when the load current exceeds a selected value; means for varying the output voltage having an input means for receiving a parabola shape periodic voltage of field frequency, whereby horizontal pincushion distortion is corrected; and a capacitor parallel coupled to said load and having a large reactance with respect to said line frequency and a small reactance relative to said field frequency.
Claim 2
Dependent Claim
161 words
A circuit for supplying an output voltage to a periodically varying load of a television line deflecTion oscillator from a power main, said circuit comprising means for rectifying the power main voltage, whereby a voltage having a ripple component is produced; a switch coupled between said rectifying means and the load; means coupled to said switch for generating a periodic pulse switching voltage having a frequency f equal to nj1, wherein n equals an interger, and f1 equals the television line frequency; means for measuring the load current; safety means coupled to said measuring means for blocking said switch when the load current exceeds a selected value; means for varying the output voltage having an input means for receiving a parabola shape periodic voltage of field frequency, whereby horizontal pincushion distortion is corrected; and a capacitor parallel coupled to said load and having a large reactance with respect to said line frequency and a small reactance relative to said field frequency.
Claim 3
Dependent Claim
26 words
A circuit as claimed in claim 1 further comprising means for applying the ripple voltage in the rectified voltage to said varying means for compensation thereof.
Claim 4
Dependent Claim
73 words
A circuit as claimed in claim 2 wherein said varying means comprises a comparison circuit having a reference voltage source, a first input coupled to receive said parabola voltage, a second input coupled to said load, and a third input coupled to receive said ripple voltage, and an output; and pulse duration modulator means coupled to said comparison circuit output, said generating means, and said switch for maintaining the load voltage substantially constant.
Claim 5
Dependent Claim
88 words
A circuit as claimed in claim 1 further comprising a transformer having a primary winding coupled between said switch and said load and at least one secondary winding; an efficiency diode having one end coupled to the junction of said primary and said switch and a second end coupled to said power main; a second diode coupled to one end of said secondary winding, the remaining end of said secondary winding being coupled to ground; whereby said second diode conducts at the same time as said efficiency diode.
Claim 6
Dependent Claim
22 words
A circuit as claimed in claim 4 further comprising a capacitor having a small capacitance coupled between said second diode and ground.
Claim 7
Dependent Claim
20 words
A circuit as claimed in claim 4 further comprising a display tube having a filament coupled to said secondary winding.
Claim 8
Dependent Claim
27 words
A circuit as claimed in claim 3 wherein said modulator comprises a thyristor, whereby after an overload or circuit turn on the switch turnoff time is small.
Claim 9
Dependent Claim
56 words
A circuit as claimed in claim 7 wherein said reference voltage means comprises a voltage dependent element and further comprising a large value capacitor shunt coupled to said voltage dependent element and a resistor coupled between said load and said element; whereby after an overload or a circuit turn on the switch turnoff time is small.
Claim 10
Dependent Claim
57 words
A circuit as claimed in claim 3 wherein said generating means comprises an oscillator coupled to said modulator and directly to said rectifying means; and further comprising a control stage coupled between said modulator and said switch and also being coupled to said rectifying means; and a resistor coupled between said rectifying means and said control stage.
Claim 11
Dependent Claim
71 words
A circuit as claimed in claim 9 further comprising a transformer having a primary winding coupled to said switch, and a secondary winding having one end coupled to said resistor; a transistor coupled to the remaining end of said secondary; a diode having a cathode coupled to the junction os said secondary and said resistor and a cathode coupled to said power main; and a resistor shunt coupled to said diode.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-12-20 | 1975-06-21 | 1975-12-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-12-20 | 1979-06-21 | 1979-12-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-12-20 | 1983-06-21 | 1983-12-21 | $7700.00 | Window Closed / Lapsed |