US5204538A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Densitometer for an electrophotographic printer using focused and unfocused reflecting beams
Assignee: Xerox Corp
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Filing: 1992-05-18
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Granted: 1993-04-20
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Expires: 2012-05-18
Abstract
Abstract An apparatus measures the reflectivity of a selected region of a surface. A first light beam is reflected from the selected region and substantially focused on a photodetector. A second light beam is reflected from the selected region and is substantially unfocused on the photodetector. A signal is derived representative of the direct reflectance of light reflected from the surface onto the photodetector as a function of the intensities of the focused light beam and the unfocused light beam detected by the photodetector.
Inventors
- 👤 Frank C. Genovese
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:57
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/50; G03G15/5033; G03G15/5041; G01; G01N; G01N21/00; G01N21/17; G01N21/55; G01N21/47; G01N21/4738; G01N2021/4764; G01N2021/4769; G01N2021/556; G01N21/25; G01N21/256; G01N2201/00; G01N2201/06; G01N2201/062; G01N2201/0621
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
127 words
An apparatus for measuring the reflectivity of a selected region of a surface, comprising: means for creating first and second light beams reflected from the selected region; a photodetector; a focusing lens positioned to focus the first light beam reflected from the selected region of the surface onto the photodetector through the axis of the focusing lens with the second light beam being reflected from the selected region and transmitted to the photodetector in a substantially unfocused manner; and processor means, operatively associated with the photodetector, for deriving a signal representative of the direct reflectance of a light beam reflected from the selected region of the surface into the photodetector as a function of the focused reflected light and the unfocused reflected light detected by the photodetector.
Claim 2
Independent Claim
127 words
An apparatus for measuring the reflectivity of a selected region of a surface, comprising: means for creating first and second light beams reflected from the selected region; a photodetector; a focusing lens positioned to focus the first light beam reflected from the selected region of the surface onto the photodetector through the axis of the focusing lens with the second light beam being reflected from the selected region and transmitted to the photodetector in a substantially unfocused manner; and processor means, operatively associated with the photodetector, for deriving a signal representative of the direct reflectance of a light beam reflected from the selected region of the surface into the photodetector as a function of the focused reflected light and the unfocused reflected light detected by the photodetector.
Claim 3
Dependent Claim
32 words
An apparatus as in claim 1, wherein the creating means comprises: a first light source for creating the first light beam; and a second light source for creating the second light beam.
Claim 4
Dependent Claim
18 words
An apparatus as in claim 2, wherein the photodetector is adapted to measure the intensity of infrared light.
Claim 5
Dependent Claim
14 words
An apparatus as in claim 2, further comprising a lens associated with the photodetector.
Claim 6
Dependent Claim
24 words
An apparatus as in claim 2, further comprising means for activating the first light source and the second light source in an alternating manner.
Claim 7
Dependent Claim
39 words
An apparatus as in claim 5, further comprising means for activating the first light source and the second light source in an alternating manner at a frequency from about 10 cycles per second to about 1000 cycles per second.
Claim 8
Dependent Claim
63 words
An apparatus as in claim 6, wherein the processor means is adapted to derive a signal representative of direct reflectance of a light beam from the selected region into the photodetector based on the difference between maxima and minima of a signal output by the photodetector as a result of the alternating activation of the first light source and the second light source.
Claim 9
Dependent Claim
23 words
An apparatus as in claim 2, wherein the second light source includes a plurality of light emitters arranged adjacent the first light source.
Claim 10
Dependent Claim
26 words
An apparatus as in claim 8, wherein the second light source includes a plurality of light emitters arranged substantially symmetrically relative to the first light source.
Claim 11
Dependent Claim
23 words
An apparatus as in claim 8, wherein the second light source includes a substantially circular light pipe disposed around the first light source.
Claim 12
Independent Claim
91 words
A method for measuring the reflectivity of a selected region of a surface, comprising the steps of: reflecting a pair of light beams through a focusing lens from the selected region of the surface; detecting focused light from one of the pairs of light beams and unfocused light from the other of the pair of light beams; and deriving a signal representative of the direct reflectance of a light beam reflected from the surface into the photodetector as a function of the focused and unfocused light detected in the detecting step.
Claim 13
Independent Claim
91 words
A method for measuring the reflectivity of a selected region of a surface, comprising the steps of: reflecting a pair of light beams through a focusing lens from the selected region of the surface; detecting focused light from one of the pairs of light beams and unfocused light from the other of the pair of light beams; and deriving a signal representative of the direct reflectance of a light beam reflected from the surface into the photodetector as a function of the focused and unfocused light detected in the detecting step.
Claim 14
Dependent Claim
15 words
A method as in claim 11, wherein the light beams are of an infrared frequency.
Claim 15
Dependent Claim
23 words
A method as in claim 11, further comprising the step of reflecting each of the pair of light beams in an alternating manner.
Claim 16
Dependent Claim
38 words
A method as in claim 13, further comprising the step of reflecting each of the pair of light beams in an alternating manner at a frequency of about 10 cycles per second to about 1000 cycles per second.
Claim 17
Dependent Claim
46 words
A method as in claim 14, wherein the deriving step includes deriving a signal representative of direct reflectance of a light beam reflected from the surface a the photodetector as a function of the difference between maxima and minima of a signal output by the photodetector.
Claim 18
Dependent Claim
22 words
A method as in claim 14, further comprising the step of moving the surface relative to the photodetector during the activating step.
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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) | 1996-04-19 | 1996-10-19 | 1997-04-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-04-19 | 2000-10-19 | 2001-04-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-04-19 | 2004-10-19 | 2005-04-20 | $7700.00 | Window Closed / Lapsed |