US5050177A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser diode driving circuit
Assignee: Ricoh Co Ltd
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Filing: 1990-11-08
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Granted: 1991-09-17
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Expires: 2010-11-08
Abstract
Abstract A laser diode driving circuit for driving a laser diode includes a driving transistor which controls a forward current of the laser diode, a photoelectric conversion element which receives an optical output of the laser diode and outputs a photocurrent proportional to the optical output, a converting circuit which converts an external light emission instruction signal into a light emission instruction signal current, and a source grounding circuit which amplifies a current which corresponds to a difference between the light emission instruction signal current from the converting circuit and the photocurrent from the photoelectric conversion element, so as to output an amplified current. This the source grounding circuit applies the amplified current to the driving transistor and controls the driving transistor so that the light emission instruction signal current becomes equal to the photocurrent.
Inventors
- 👤 Hidetoshi Ema
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 19:14
CPC Classifications
G; G11; G11B; G11B7/00; G11B7/12; G11B7/125; G11B7/126; H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
130 words
A laser diode driving circuit for driving a laser diode comprising: a driving transistor controlling a forward current of the laser diode; photoelectric conversion means for receiving an optical output of the laser diode and for outputting a photocurrent proportional to the optical output; converting means for converting an external light emission instruction signal into a light emission instruction signal current; and a source grounding circuit amplifying a current which corresponds to a difference between the light emission instruction signal current from said converting means and the photocurrent from said photoelectric conversion means, so as to output an amplified current, said source grounding circuit applying the amplified current to said driving transistor and controlling said driving transistor so that the light emission instruction signal current becomes equal to the photocurrent.
Claim 2
Dependent Claim
130 words
A laser diode driving circuit for driving a laser diode comprising: a driving transistor controlling a forward current of the laser diode; photoelectric conversion means for receiving an optical output of the laser diode and for outputting a photocurrent proportional to the optical output; converting means for converting an external light emission instruction signal into a light emission instruction signal current; and a source grounding circuit amplifying a current which corresponds to a difference between the light emission instruction signal current from said converting means and the photocurrent from said photoelectric conversion means, so as to output an amplified current, said source grounding circuit applying the amplified current to said driving transistor and controlling said driving transistor so that the light emission instruction signal current becomes equal to the photocurrent.
Claim 3
Dependent Claim
19 words
The laser diode driving circuit as claimed in claim 1, wherein said driving transistor includes a field effect transistor.
Claim 4
Dependent Claim
20 words
The laser diode driving circuit as claimed in claim 1, wherein said photoelectric conversion means includes a light receiving element.
Claim 5
Dependent Claim
93 words
The laser diode driving circuit as claimed in claim 1, which further comprises a first terminal supplying a first power source voltage, a second terminal supplying a second power source voltage and a third terminal connected to ground, said driving transistor being coupled is series with the laser diode between said first and third terminals, said photoelectric conversion means being coupled to said first terminal, said converting means being coupled to said second terminal, said source grounding circuit being coupled to said first and third terminals, said driving transistor and said converting means.
Claim 6
Dependent Claim
25 words
The laser diode driving circuit as claimed in claim 4, wherein said photoelectric conversion means is coupled between said first terminal and said converting means.
Claim 7
Dependent Claim
52 words
The laser diode driving circuit as claimed in claim 4, which further comprises a first current source coupled between said first terminal and said converting means, and a second current source coupled to said second terminal, said source grounding circuit and a node between said first current source and said converting means.
Claim 8
Dependent Claim
26 words
The laser diode driving circuit as claimed in claim 6, wherein said photoelectric conversion means is coupled between said first terminal and said second current source.
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) | 1994-09-16 | 1995-03-18 | 1995-09-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-16 | 1999-03-18 | 1999-09-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-16 | 2003-03-18 | 2003-09-17 | $7700.00 | Window Closed / Lapsed |