US5335239A
Expired / Lapsed
US
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Thermal compensation for laser diodes using active feedback
Assignee: Eastman Kodak Co
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Filing: 1993-03-17
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Granted: 1994-08-02
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Expires: 2013-03-17
Abstract
Abstract Providing thermal compensation for laser diodes used in intensity modulated applications by using active feedback. A PIN diode serves as a laser light output sensor for the closed loop feedback system. The input from the PIN diode is convened into a voltage and then fed into a feedback amplifier. The PIN diode current is slightly dependent upon the temperature due to transmission effects of materials within the laser diode assembly. A temperature voltage signal generated by a semiconductor temperature sensor may be used as a second input to the feedback amplifier. The output of this amplifier is sampled at periodic intervals such as once a scan line, by a sample and hold amplifier. The output of the sample and hold amplifier is added to a data dependent modulated current reference in a summing amplifier. The output of the summing amplifier is the resultant sensor and provides an input reference to the laser driver integrated circuit.
Inventors
- 👤 Karen L. Herczeg
- 👤 David M. McVay
- 👤 Daniel J. Phelps
- 👤 Kimberley C. Bell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:24
CPC Classifications
H; H01; H01S; H01S5/00; H01S5/06; H01S5/068; H01S5/0683; H01S5/06832; H01S5/06804
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
144 words
A drive circuit for driving a semiconductor laser having a light output that is modulated in response to digital video data comprising: means for generating a sample signal to establish a sampling period; means for generating a first signal corresponding to said light output at a maximum level to produce a threshold current reference; means for generating a second signal corresponding to the ambient temperature of said laser; amplifier means for generating an error signal which is proportional to said first and second signal; means for measuring the current level of said laser when modulated to produce a maximum analog modulated current reference signal; means for summing said error signal and said modulated current reference signal to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 2
Dependent Claim
144 words
A drive circuit for driving a semiconductor laser having a light output that is modulated in response to digital video data comprising: means for generating a sample signal to establish a sampling period; means for generating a first signal corresponding to said light output at a maximum level to produce a threshold current reference; means for generating a second signal corresponding to the ambient temperature of said laser; amplifier means for generating an error signal which is proportional to said first and second signal; means for measuring the current level of said laser when modulated to produce a maximum analog modulated current reference signal; means for summing said error signal and said modulated current reference signal to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 3
Dependent Claim
20 words
A drive circuit as set forth in claim 1 wherein the amplifier means takes the form of a feedback amplifier.
Claim 4
Dependent Claim
29 words
A drive circuit as set forth in claim 1 wherein the means for measuring the current level of said laser takes the form of a sample and hold amplifier.
Claim 5
Dependent Claim
25 words
A drive circuit as set forth in claim 1 wherein the means for driving the laser takes the form of a laser driver integrated circuit.
Claim 6
Dependent Claim
187 words
An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising: means for generating a sample signal to establish a test period; means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal; means for generating a second signal corresponding to the ambient temperature of said laser diode; means for generating a third threshold current reference signal that is proportional to said first and second signals; means for sampling said third signal at periodic intervals; means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal; means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 7
Dependent Claim
187 words
An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising: means for generating a sample signal to establish a test period; means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal; means for generating a second signal corresponding to the ambient temperature of said laser diode; means for generating a third threshold current reference signal that is proportional to said first and second signals; means for sampling said third signal at periodic intervals; means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal; means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 8
Dependent Claim
28 words
An optical information recording/reproducing apparatus as set forth in claim 5 wherein the means for sampling said third signal takes the form of a sample and hold amplifier.
Claim 9
Dependent Claim
22 words
An optical information recording/reproducing apparatus as set forth in claim 5 wherein means for combining takes the form of a summing amplifier.
Claim 10
Independent Claim
162 words
A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal; generating a second signal that corresponds to the ambient temperature of said laser; generate and amplify an error signal which is proportional to said first and second signals combined; measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal; sum said error signal and said modulated current reference signal to produce a drive signal; and operate the laser diode in response to said drive signal and modulate the laser with the digital video data.
Claim 11
Independent Claim
162 words
A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal; generating a second signal that corresponds to the ambient temperature of said laser; generate and amplify an error signal which is proportional to said first and second signals combined; measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal; sum said error signal and said modulated current reference signal to produce a drive signal; and operate the laser diode in response to said drive signal and modulate the laser with the digital video data.
Claim 12
Dependent Claim
32 words
The method as set forth in claim 8 wherein the first signal corresponds to the light output of said laser diode is generated by a back facet PIN diode of the laser.
Claim 13
Independent Claim
163 words
A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal indicating the power level of the laser diode operating at a maximum power level; generating a second signal corresponding to the ambient temperature of said laser diode; generating a third threshold current reference signal that corresponds to said first and second signals; sampling said third signal at periodic intervals; measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal; combine the threshold current reference signal with the modulated current reference signal to produce a drive signal; and drive the laser in response to said drive signal and modulate the laser in response to the digital video data.
Claim 14
Independent Claim
163 words
A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal indicating the power level of the laser diode operating at a maximum power level; generating a second signal corresponding to the ambient temperature of said laser diode; generating a third threshold current reference signal that corresponds to said first and second signals; sampling said third signal at periodic intervals; measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal; combine the threshold current reference signal with the modulated current reference signal to produce a drive signal; and drive the laser in response to said drive signal and modulate the laser in response to the digital video data.
Claim 15
Dependent Claim
25 words
The method of thermal compensation for a laser diode as set forth in claim 10 wherein sampling of said third signal occurs once a line.
Claim 16
Dependent Claim
130 words
A drive circuit for driving a semiconductor laser having a light output that is modulated in response to digital video data comprising: means for generating a sample signal to establish a sampling period; means for generating a first signal corresponding to said light output at a maximum level to produce a threshold current reference; amplifier means for generating an error signal which is proportional to said first and second signal; means for measuring the current level of said laser when modulated to produce a maximum analog modulated current reference signal; means for summing said error signal and said modulated current reference signal to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 17
Dependent Claim
130 words
A drive circuit for driving a semiconductor laser having a light output that is modulated in response to digital video data comprising: means for generating a sample signal to establish a sampling period; means for generating a first signal corresponding to said light output at a maximum level to produce a threshold current reference; amplifier means for generating an error signal which is proportional to said first and second signal; means for measuring the current level of said laser when modulated to produce a maximum analog modulated current reference signal; means for summing said error signal and said modulated current reference signal to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 18
Dependent Claim
170 words
An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising: means for generating a sample signal to establish a test period; means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal; means for generating a third threshold current reference signal that is proportional to said first signal; means for sampling said third signal at periodic intervals; means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal; means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 19
Dependent Claim
170 words
An optical information recording/reproducing apparatus having a laser diode for radiating a laser beam capable of being modulated by digital video data and writing on a photostatic receiver material controlling the laser power level during a test period, said apparatus comprising: means for generating a sample signal to establish a test period; means for indicating the power level of the laser diode operating at a maximum level to produce a threshold current level in the form of a first signal; means for generating a third threshold current reference signal that is proportional to said first signal; means for sampling said third signal at periodic intervals; means for measuring the current level of said laser diode when fully modulated during said test period to produce a modulated current reference signal; means for combining the threshold current reference signal with the maximized modulated current to produce a drive signal; and means for driving said laser in response to said drive signal and modulating the laser in response to the digital video data.
Claim 20
Independent Claim
146 words
A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal; generate and amplify an error signal which is proportional to said first signal; measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal; sum said error signal and said modulated current reference signal to produce a drive signal; and operate the laser diode in response to said drive signal and modulate the laser with the digital video data.
Claim 21
Independent Claim
146 words
A method of providing thermal compensation for a laser diode that is modulated in response to digital video data and writing on a photostatic receiver material, said laser diode operating at a maximum output during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal corresponding to the light output of said laser diode operating at a maximum level to produce a first signal; generate and amplify an error signal which is proportional to said first signal; measure the current level of said laser when modulated by said digital video data to obtain an analog modulated current reference signal; sum said error signal and said modulated current reference signal to produce a drive signal; and operate the laser diode in response to said drive signal and modulate the laser with the digital video data.
Claim 22
Independent Claim
148 words
A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal indicating the power level of the laser diode operating at a maximum power level; generating a second threshold current reference signal that corresponds to said first signal; sampling said second signal at periodic intervals; measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal; combine the threshold current reference signal with the modulated current reference signal to produce a drive signal; and drive the laser in response to said drive signal and modulate the laser in response to the digital video data.
Claim 23
Independent Claim
148 words
A method of thermal compensation for a laser diode that is modulated in response to a digital video data and writing on a photostatic receiver material while controlling said laser power during a test period, said method comprising the steps of: generating a sample signal to establish a test period; generating a first signal indicating the power level of the laser diode operating at a maximum power level; generating a second threshold current reference signal that corresponds to said first signal; sampling said second signal at periodic intervals; measuring the current level of said laser diode when modulated by said digital video data to produce a modulated current reference signal; combine the threshold current reference signal with the modulated current reference signal to produce a drive signal; and drive the laser in response to said drive signal and modulate the laser in response to the digital video data.
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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) | 1997-08-01 | 1998-01-31 | 1998-08-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-01 | 2002-01-31 | 2002-08-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-01 | 2006-01-31 | 2006-08-02 | $7700.00 | Window Closed / Lapsed |