Patent US5340975A successfully refreshed from Google Patents.
US5340975A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface
Assignee: 3M Co
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Filing: 1993-01-29
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Granted: 1994-08-23
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Expires: 2013-01-29
Abstract
Abstract A method and an apparatus is provided for reducing the effects of laser noise and for improving modulation transfer function in scanning a surface of a photoconductive plate with a spot of light through use of a time-light intensity integration method. The method comprises pulse synchronization or infrared synchronization to control activation and deactivation of signal detection laser light beams.
Inventors
- 👤 Peter J. Vogelgesang
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:29
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/40025; H04N1/4005; H04N1/40031; H04N1/40037
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
173 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam and the second light beam have different wavelengths.
Claim 2
Independent Claim
173 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam and the second light beam have different wavelengths.
Claim 3
Independent Claim
178 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam is a blue-green laser and the second light beam is an infrared laser.
Claim 4
Independent Claim
178 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam is a blue-green laser and the second light beam is an infrared laser.
Claim 5
Independent Claim
177 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which one of the light beams has a wavelength at which the photoconductive surface is not photoconductive.
Claim 6
Independent Claim
177 words
A method for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising the steps of: a) providing a laser light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) generating, using the photodetector, a current which is proportional to the instantaneous light intensity of the first light beam; c) applying the generated current to an integrator to produce an output voltage proportional to the time-light intensity integral of the first light beam; d) feeding the output voltage to a voltage comparator to compare the output voltage with a pre-set voltage to create an output signal; and e) using the output signal to control a modulator so that when the value of preset voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which one of the light beams has a wavelength at which the photoconductive surface is not photoconductive.
Claim 7
Independent Claim
165 words
A system for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising: a) a light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) a photodetector to generate a current which is proportional to the instantaneous light intensity of the first light beam; c) an integrator which receives the current from the photodetector and which produces an output voltage proportional to the time-light intensity integral of the first light beam; d) comparator means for comparing the output voltage with a pre-set voltage to create an output signal; e) a modulator controlled by the comparator means output signal so that when the value of pre-set voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam and the second light beam have different wavelengths.
Claim 8
Independent Claim
165 words
A system for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising: a) a light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) a photodetector to generate a current which is proportional to the instantaneous light intensity of the first light beam; c) an integrator which receives the current from the photodetector and which produces an output voltage proportional to the time-light intensity integral of the first light beam; d) comparator means for comparing the output voltage with a pre-set voltage to create an output signal; e) a modulator controlled by the comparator means output signal so that when the value of pre-set voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam and the second light beam have different wavelengths.
Claim 9
Independent Claim
170 words
A system for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising: a) a light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) a photodetector to generate a current which is proportional to the instantaneous light intensity of the first light beam; c) an integrator which receives the current from the photodetector and which produces an output voltage proportional to the time-light intensity integral of the first light beam; d) comparator means for comparing the output voltage with a pre-set voltage to create an output signal; e) a modulator controlled by the comparator means output signal so that when the value of pre-set voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam is a blue-green laser and the second light beam is an infrared laser.
Claim 10
Independent Claim
170 words
A system for reducing the effects of laser noise and for improving modulation transfer function in scanning a photoconductive surface with a spot of light, comprising: a) a light source for directing a first light beam onto a photoconductive surface and for directing a second light beam to a photodetector; b) a photodetector to generate a current which is proportional to the instantaneous light intensity of the first light beam; c) an integrator which receives the current from the photodetector and which produces an output voltage proportional to the time-light intensity integral of the first light beam; d) comparator means for comparing the output voltage with a pre-set voltage to create an output signal; e) a modulator controlled by the comparator means output signal so that when the value of pre-set voltage in the comparator is exceeded the modulator prevents substantially all of the transmission of the light past the modulator; in which the first light beam is a blue-green laser and the second light beam is an infrared laser.
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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) | 1997-08-22 | 1998-02-21 | 1998-08-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-22 | 2002-02-21 | 2002-08-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-22 | 2006-02-21 | 2006-08-23 | $7700.00 | Window Closed / Lapsed |