US3755697A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light-emitting diode driver
Assignee: HP Inc
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Filing: 1971-11-26
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Granted: 1973-08-28
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Expires: 1991-11-26
Abstract
Abstract A transistor is driven into conduction by pulses from an external signal source and has an inductance for a collector load. A light-emitting diode (LED) is connected across the inductance and is forward-biased for a short period each time after the transistor ceases conduction. Repetitive pulsing of the LED produces illumination at low-average current consumption.
Inventors
- 👤 D Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 22:58
CPC Classifications
H; H03; H03K; H03K3/00; H03K3/02; H03K3/42
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
85 words
A circuit comprising: a light-emitting diode; inductance means coupled in parallel with said light-emitting diode; a voltage source; means for coupling said voltage source to the parallel combination of said light-emitting diode and said inductance means, said coupling means including switching means for applying current pulses to said light-emitting diode, said switching means being operable in a first conductive mode to store energy in said inductance means, and in a second nonconductive mode to produce current flow from said inductance means through said light-emitting diode.
Claim 2
Dependent Claim
85 words
A circuit comprising: a light-emitting diode; inductance means coupled in parallel with said light-emitting diode; a voltage source; means for coupling said voltage source to the parallel combination of said light-emitting diode and said inductance means, said coupling means including switching means for applying current pulses to said light-emitting diode, said switching means being operable in a first conductive mode to store energy in said inductance means, and in a second nonconductive mode to produce current flow from said inductance means through said light-emitting diode.
Claim 3
Dependent Claim
52 words
The circuit of claim 1 wherein said inductance means is a single inductor element having one end terminal connected to said switching means and the other end terminal connected to said voltage source, and wherein said coupling means is configured to reverse-bias said light-emitting diode in said first conductive mode of operation.
Claim 4
Dependent Claim
53 words
The circuit of claim 1, wherein said inductance means includes a transformer having primary and secondary windings, said primary winding being coupled by said coupling means to said voltage source, and said secondary winding being coupled to said light-emitting diode, thereby to provide d.c. isolation of said voltage source from said light-emitting diode.
Claim 5
Dependent Claim
46 words
The circuit of claim 1 wherein said switching means is a transistor having control electrode means for receiving input pulses, and a pair of main current-carrying electrodes coupled in series between said voltage source and the parallel combination of said inductance means and said light-emitting diode.
Claim 6
Dependent Claim
45 words
The circuit of claim 1, wherein said light-emitting diode and said voltage source each have a pair of opposite polarity terminals, and wherein said coupling means is configured to couple each terminal of said light-emitting diode to the opposite polarity terminal of the voltage source.
Claim 7
Dependent Claim
60 words
The circuit of claim 5, wherein said light-emitting diode has an anode and a cathode electrode and said voltage source has a positive and a negative output terminal, and wherein said coupling means is configured to connect said anode electrode to said negative output terminal through said switching means and to connect said cathode electrode to said positive output terminal.
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) | 1976-08-27 | 1977-02-26 | 1977-08-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-27 | 1981-02-26 | 1981-08-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-27 | 1985-02-26 | 1985-08-28 | $7700.00 | Window Closed / Lapsed |