US4806873A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Laser diode driving circuit
Assignee: Toshiba Corp
•
Filing: 1988-04-14
•
Granted: 1989-02-21
•
Expires: 2008-04-14
Abstract
Abstract A laser diode circuit has a photodiode which monitors the light output which is outputted by the laser diode and generates a photovoltaic current that corresponds to the level of the light output, a reference current selection device which selects a required reference current by switching among a plurality of reference current sources that are set to values of mutually different current values, and an amplifying apparatus which, by receiving a signal that corresponds to the photovoltaic current, controls the forward current of the laser diode so as to bring the photovoltaic current to a selected reference current. Instead of the above construction, there may be employed a construction which has a voltage transforming selector which generates a photovoltaic current signal voltage that corresponds to the photovoltaic current, a reference voltage selection device which selects a required reference voltage by switching among a plurality of reference voltage sources that are set to values of mutually different reference voltages, and an amplifying apparatus which, by receiving the photovoltaic current signal voltage and a selected reference voltage, controls the forward current of the laser diode so as to bring the photovoltaic current signal voltage equal to the selected reference voltage.
Inventors
- 👤 Katsumi Nagano
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 20:00
CPC Classifications
H; H01; H01S; H01S3/00; H01S5/00; H01S5/06; H01S5/068; H01S5/0683
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
177 words
A laser diode driving circuit comprising: generating means for monitoring light output from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; a plurality of reference current sources respectively set to separate reference current values; current selecting means, disposed corresponding to the plurality of reference current sources, for selecting a required reference current proportional to the level of the light output by switching the plurality of reference current sources; and control means for inputting a signal that corresponds to the photovoltaic current and for controlling the forward current of the laser diode so as to set the photovoltaic current to be equal to a selected reference current, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the current selecting means, a second input terminal having a substantially constant potential, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
Claim 2
Dependent Claim
177 words
A laser diode driving circuit comprising: generating means for monitoring light output from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; a plurality of reference current sources respectively set to separate reference current values; current selecting means, disposed corresponding to the plurality of reference current sources, for selecting a required reference current proportional to the level of the light output by switching the plurality of reference current sources; and control means for inputting a signal that corresponds to the photovoltaic current and for controlling the forward current of the laser diode so as to set the photovoltaic current to be equal to a selected reference current, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the current selecting means, a second input terminal having a substantially constant potential, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
Claim 3
Dependent Claim
32 words
The laser diode driving circuit as claimed in claim 1 wherein said control means comprises an operational amplifier, and the output terminal of the operational amplifier is connected to the laser diode.
Claim 4
Dependent Claim
41 words
The laser diode driving circuit as claimed in claim 1 wherein said current selecting means has a multipolar switch connected to said control means and the generating means, and the plurality of reference current sources being connected to the multipolar switch.
Claim 5
Dependent Claim
42 words
The laser diode driving circuit as claimed in claim 1 wherein said current selecting means has a plurality of switches connected to the control means and the generating means, and the plurality of reference current sources being connected to the multipolar switch.
Claim 6
Dependent Claim
42 words
The laser diode driving circuit as claimed in claim 1 wherein said current selecting means has a plurality of differential pairs connected to the control means and the generating means, and a plurality of second transistors connected to the differential pair transistors.
Claim 7
Dependent Claim
36 words
The laser diode driving circuit as claimed in claim 1 wherein said current selecting means has a transistor connected to the control means and the generating means, and a second control means connected to the transistor.
Claim 8
Dependent Claim
23 words
The laser diode driving circuit as claimed in claim 1 wherein said current selecting means comprises a switch and a constant current source.
Claim 9
Dependent Claim
18 words
The laser diode driving circuit as claimed in claim 7 wherein said constant current source comprises a resistor.
Claim 10
Dependent Claim
46 words
A laser diode driving circuit as claimed in claim 1, wherein said reference current sources comprise a plurality of resistors, and said current selecting means comprises a rotary switch electrically connected to the photodiode for selecting the required reference current by switching the plurality of resistors.
Claim 11
Dependent Claim
38 words
A laser diode driving circuit as claimed in claim 1, wherein said current selecting means comprises a rotary switch electrically connected to the photodiode for selecting the required reference current by switching the plurality of reference current sources.
Claim 12
Dependent Claim
186 words
A laser diode driving circuit comprising: generating means for monitoring light output outputted from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; voltage converting means for generating a voltage signal that corresponds to the photovoltaic current; a plurality of reference voltage sources respectively set to separate reference voltage values; voltage selecting means, disposed corresponding to the plurality of reference voltage sources, for selecting a required reference voltage proportional to the level of the light output by switching the plurality of separate reference voltage values; and control means for controlling the forward current of the laser diode so as to bring the voltage signal equal to the selected reference voltage, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the voltage converting means, a second input terminal having a substantially constant potential selected by the voltage selecting means, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
Claim 13
Dependent Claim
186 words
A laser diode driving circuit comprising: generating means for monitoring light output outputted from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; voltage converting means for generating a voltage signal that corresponds to the photovoltaic current; a plurality of reference voltage sources respectively set to separate reference voltage values; voltage selecting means, disposed corresponding to the plurality of reference voltage sources, for selecting a required reference voltage proportional to the level of the light output by switching the plurality of separate reference voltage values; and control means for controlling the forward current of the laser diode so as to bring the voltage signal equal to the selected reference voltage, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the voltage converting means, a second input terminal having a substantially constant potential selected by the voltage selecting means, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
Claim 14
Dependent Claim
29 words
The laser diode driving circuit as claimed in claim 11 wherein said control means comprises an operational amplifier the output terminal of which is connected to the laser diode.
Claim 15
Dependent Claim
34 words
The laser diode driving circuit as claimed in claim 11 wherein said control means comprises an operational amplifier an input terminal of which is connected to the generating means and the voltage connecting means.
Claim 16
Dependent Claim
28 words
The laser diode driving circuit as claimed in claim 11 wherein said voltage selecting means has a multipolar switch connected to an input terminal of the control means.
Claim 17
Dependent Claim
29 words
The laser diode driving circuit as claimed in claim 11 wherein said voltage selecting means has a plurality of switches connected to an input terminal of the control means.
Claim 18
Dependent Claim
36 words
The laser diode driving circuit as claimed in claim 11 wherein said voltage selecting means has a multipolar switch connected to a terminal of the control means, and a current source connected to the multipolar switch.
Claim 19
Dependent Claim
29 words
The laser diode driving circuit as claimed in claim 11 wherein the output terminal of the control means is connected to a driving transistor connected to the laser diode.
Claim 20
Dependent Claim
35 words
The laser diode driving circuit as claimed in claim 11 wherein said voltage selecting means has transistor pairs connected to a terminal of the control means, and a current source connected to the transistor pairs.
Claim 21
Dependent Claim
27 words
The laser diode driving circuit as claimed in claim 17 wherein said control means comprises a transistor pair connected to a power supply and the driving transistor.
Claim 22
Dependent Claim
39 words
The laser diode driving circuit as claimed in claim 11 wherein said control means comprises a plurality of operational amplifiers, and the output terminal of each operational amplifier is connected to a driving transistor connected to the laser diode.
Claim 23
Dependent Claim
43 words
The laser diode driving circuit as claimed in claim 20 wherein said voltage selecting means has a plurality of differential transistors connected to a constant current terminal of each operational amplifier, and a constant current source connected to each of the differential transistors.
Claim 24
Dependent Claim
28 words
The laser diode driving circuit as claimed in claim 20 wherein each of the operational amplifiers comprises paired transistors connected to a power supply and each driving transistor.
Claim 25
Dependent Claim
25 words
The laser diode driving circuit as claimed in claim 11 wherein said voltage selecting means has a plurality of switches in parallel to each other.
Claim 26
Dependent Claim
45 words
A laser diode driving circuit as claimed in claim 11, wherein said reference voltage sources comprise a plurality of resistors, and said voltage selecting means comprises a rotary switch electrically connectable to the respective resistors for selecting the required reference voltage by switching the resistors.
Claim 27
Dependent Claim
46 words
A laser diode driving circuit as claimed in claim 11, wherein said reference voltage sources comprise a plurality of resistors, and said voltage selecting means comprises a plurality of switches electrically connectable to the respective resistors for selecting the required reference voltage by switching the resistors.
Claim 28
Dependent Claim
45 words
A laser diode driving circuit as claimed in claim 11, wherein the output terminal of the control means is electrically connected to a driving transistor electrically connected to the laser diode, and said control means further comprises transistor pairs electrically connected to the driving transistor.
Claim 29
Dependent Claim
186 words
A laser diode driving circuit comprising: generating means for monitoring light output from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; reference current selecting means for selecting a required reference current proportional to the level of the light output by switching reference current values and changing the required reference current by changing the voltage of the variable voltage source, said reference current selecting means having a variable voltage source and transistor means operated by the operation of the variable voltage source; and control means for inputting a signal that corresponds to the photovoltaic current and controlling the forward current of the laser diode so as to set the photovoltaic current equal to the selected reference current, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the transistor means, a second input terminal having a substantially constant potential, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
Claim 30
Dependent Claim
186 words
A laser diode driving circuit comprising: generating means for monitoring light output from a laser diode and having a photodiode for generating a photovoltaic current that is proportional to the level of the light output; reference current selecting means for selecting a required reference current proportional to the level of the light output by switching reference current values and changing the required reference current by changing the voltage of the variable voltage source, said reference current selecting means having a variable voltage source and transistor means operated by the operation of the variable voltage source; and control means for inputting a signal that corresponds to the photovoltaic current and controlling the forward current of the laser diode so as to set the photovoltaic current equal to the selected reference current, said control means having a first input terminal for inputting a signal based on the operation of the photodiode and the transistor means, a second input terminal having a substantially constant potential, and an output terminal for outputting to the laser diode a signal based on the input signals of the first and second input terminals.
References Cited (Backward Citations)
US3898583A
Cited
US3996526A
Cited
US3946335A
Cited
US4344173A
Cited
US4339822A
Cited
US4369525A
Cited
US4592057A
Cited
US4484331A
Cited
US4577320A
Cited
US4611352A
Cited
US4621376A
Cited
US4612671A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-02-21 | 1992-08-22 | 1993-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-02-21 | 1996-08-22 | 1997-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-02-21 | 2000-08-22 | 2001-02-21 | $7700.00 | Window Closed / Lapsed |