US3832065A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Drum track detector
Assignee: Xerox Corp
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Filing: 1973-03-23
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Granted: 1974-08-27
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Expires: 1993-03-23
Abstract
Abstract A method of and an apparatus for detecting a medium includes means or steps for providing a light beam and means or steps for detecting the light after it is reflected from the medium. The light providing means is positioned to direct a light beam onto a substantially planar surface at a predetermined angle of incidence. The presence of a sheet medium that may be laid on the planar surface is detected by detecting a portion of the light reflected by the sheet medium. Preferably, the detecting means is positioned so that it senses a portion of light scattered or diffused by the paper but is positioned outside of the path of the reflected light from the planar surface so that it does not detect the reflected light. In this manner, the apparatus is rendered to be capable of detecting the presence of sheet medium that diffuses the light but avoid detecting the reflected light from a planar surface. The ability to discriminate is enhanced by pulsing the light at a given repetition rate and by providing an amplifying arrangement in the photodetecting means that is tuned to the repetitive rate of the pulsed light. The discrimination capability is further enhanced by choosing a light beam that has an energy spectrum which is substantially transparent to the planar surface, i.e., is substantially absorbed by the planar surface but which is non-transparent to the sheet medium; i.e., is bounced back and diffused substantially by the sheet medium.
Inventors
- 👤 B Sullivan
- 👤 D Baxter
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 17:53
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/70; G03G15/706
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
135 words
In an electrostatographic reproducing apparatus having a photosensitive plate which is charged, imagewise exposed and developed to form an image of an original which is then transferred to a transfer medium such as a copy sheet of paper brought in contact with the layer, wherein said photosensitive plate is of the type that absorbs substantially all of the light applied thereto during the imagewise exposure and said transfer medium is of the type that reflects the light, an apparatus for detecting the continued presence of the transfer medium, comprising: means for applying a train of light pulses of a predetermined frequency against said plate, and photodetecting means tuned to detect the presence of a train of light pulses of the predetermined frequency reflected from said transfer medium, whereby said photodetecting means is rendered noise immune.
Claim 2
Dependent Claim
135 words
In an electrostatographic reproducing apparatus having a photosensitive plate which is charged, imagewise exposed and developed to form an image of an original which is then transferred to a transfer medium such as a copy sheet of paper brought in contact with the layer, wherein said photosensitive plate is of the type that absorbs substantially all of the light applied thereto during the imagewise exposure and said transfer medium is of the type that reflects the light, an apparatus for detecting the continued presence of the transfer medium, comprising: means for applying a train of light pulses of a predetermined frequency against said plate, and photodetecting means tuned to detect the presence of a train of light pulses of the predetermined frequency reflected from said transfer medium, whereby said photodetecting means is rendered noise immune.
Claim 3
Dependent Claim
35 words
The apparatus according to claim 1, wherein the repetition rate of the train of light pulses is selected at a particular frequency substantially above the frequency of the AC power supply to the reproducing apparatus.
Claim 4
Dependent Claim
19 words
The apparatus according to claim 2, wherein said photodetecting means includes a bandpass filter tuned to said particular frequency.
Claim 5
Dependent Claim
26 words
The apparatus according to claim 3, wherein said photodetecting means includes a peak detector for producing a DC output from the output of said bandpass filter.
Claim 6
Dependent Claim
20 words
The apparatus according to claim 4, including a preamplifier for amplifying detected signal before it is applied to said filter.
Claim 7
Dependent Claim
21 words
The apparatus according to claim 1, the light is pulsed at a frequency above the frequency of stray light generally encountered.
Claim 8
Dependent Claim
73 words
A detecting apparatus for detecting a presence of a medium having a plane surface which reflects and diffuses or scatters the reflected light, comprising: means for applying a light beam to said surface at a predetermined angle of incidence, and a photodetecting means positioned at a location outside of a zone of an area where a reflected light would be cast if said surface is planar, for detecting the presence of said medium.
Claim 9
Dependent Claim
73 words
A detecting apparatus for detecting a presence of a medium having a plane surface which reflects and diffuses or scatters the reflected light, comprising: means for applying a light beam to said surface at a predetermined angle of incidence, and a photodetecting means positioned at a location outside of a zone of an area where a reflected light would be cast if said surface is planar, for detecting the presence of said medium.
Claim 10
Dependent Claim
39 words
The apparatus according to claim 7, wherein said medium is a sheet member such as a copy sheet which is supported by a substrate medium having a planar surface and is of a type that reflects an incident light.
Claim 11
Dependent Claim
26 words
The apparatus according to claim 8, second photodetecting means positioned within the zone of reflection for detecting the light reflected from the surface of said substrate.
Claim 12
Dependent Claim
19 words
The apparatus according to claim 9, wherein said light applying means is adapted to apply a coherent light beam.
Claim 13
Dependent Claim
66 words
The apparatus according to claim 9, said means for applying the light beam includes a first light pipe aligned to direct the light beam at said predetermined angle, and said photodetecting means includes a second light pipe positioned outside of said zone of reflection for guiding a portion of the diffused or scattered light and a photocell for sensing the light from said second light pipe.
Claim 14
Dependent Claim
26 words
The apparatus accorDing to claim 11, wherein said first light pipe is positioned so that said predetermined angle of incidence is 57* - or + 1.5*.
Claim 15
Dependent Claim
46 words
The apparatus according to claim 12, said means for providing the light beam includes means for pulsing the light at a predetermined repetition rate, and said photodetecting means includes a bandpass filter tuned to said repetition rate for filtering out noise signals from the detected light.
Claim 16
Independent Claim
109 words
An apparatus for detecting and discriminating the presence of a first member having first surface which reflects an incident light and diffuses or scatters the reflected light from a second member having a planar surface which is disposable in parallel with said first surface and which absorbs or reflects an incident light, but does not diffuse or scatter the incident light, comprising: means for applying a light beam at a predetermined angle of incidence onto a surface of a member, and first photodetecting means positioned outside of a zone of reflection for detecting the presence of diffused or scattered light and thereby determining the presence of said first member.
Claim 17
Independent Claim
109 words
An apparatus for detecting and discriminating the presence of a first member having first surface which reflects an incident light and diffuses or scatters the reflected light from a second member having a planar surface which is disposable in parallel with said first surface and which absorbs or reflects an incident light, but does not diffuse or scatter the incident light, comprising: means for applying a light beam at a predetermined angle of incidence onto a surface of a member, and first photodetecting means positioned outside of a zone of reflection for detecting the presence of diffused or scattered light and thereby determining the presence of said first member.
Claim 18
Dependent Claim
68 words
The apparatus according to claim 14, wherein said means for applying the light beam includes an oscillator for generating an output pulse train at a repetition rate substantially above 60 Hz and a light emitting diode for generating a train of light pulses in response to the output of said oscillator and said photodetecting means includes an amplifier tuned to receive the detected light having said repetition rate.
Claim 19
Dependent Claim
19 words
The apparatus according to claim 15, including a peak detecting means for rectifying the output of said tuned amplifier.
Claim 20
Dependent Claim
31 words
The apparatus according to claim 16, wherein the angle of incidence of the light beam is 57* - or + 1.5* with respect to the plane of said second planar surface.
Claim 21
Dependent Claim
42 words
The apparatus according to claim 14, including a second photodetecting means positioned in the path of the reflected light to detect the reflected light from said planar surface and thereby detect the presence of said second member having a planar reflecting surface.
Claim 22
Dependent Claim
178 words
In an electrostatographic reproducing apparatus having a photosensitive plate having a planar surface, said plate being partially transparent and partially reflective, means for charging the plate, means for exposing the plate to light to form a latent electrostatic image of a document original, means for developing the image, means for laying a copy sheet on said plate, said sheet being of substantially reflective character that reflects and scatters or diffuses the incident light, means for transferring the image to said copy sheet, and means for removing the copy sheet from said plate, the improvement which comprises an apparatus for detecting the failure of said removing means to remove the copy sheet, said apparatus comprising: means for applying a light at a predetermined angle of incidence to the surface of said plate, and photodetecting means positioned outside of the zone where the light reflected from said plate would fall, for detecting the reflected and scattered or diffused light from the copy sheet and thereby detecting the failure of said removing means to remove the copy sheet from said plate.
Claim 23
Dependent Claim
178 words
In an electrostatographic reproducing apparatus having a photosensitive plate having a planar surface, said plate being partially transparent and partially reflective, means for charging the plate, means for exposing the plate to light to form a latent electrostatic image of a document original, means for developing the image, means for laying a copy sheet on said plate, said sheet being of substantially reflective character that reflects and scatters or diffuses the incident light, means for transferring the image to said copy sheet, and means for removing the copy sheet from said plate, the improvement which comprises an apparatus for detecting the failure of said removing means to remove the copy sheet, said apparatus comprising: means for applying a light at a predetermined angle of incidence to the surface of said plate, and photodetecting means positioned outside of the zone where the light reflected from said plate would fall, for detecting the reflected and scattered or diffused light from the copy sheet and thereby detecting the failure of said removing means to remove the copy sheet from said plate.
Claim 24
Dependent Claim
44 words
The apparatus according to claim 19, wherein said means for applying a light beam includes means for modulating the light beam so that a train of light pulses of a predetermined repetition rate is applied to the surfaces of said plate of copy sheet.
Claim 25
Dependent Claim
34 words
The apparatus according to claim 20, wherein said photodetecting means includes means for sensing a light beam in the form of a train of pulses reflected and scattered or diffused from said copy sheet.
Claim 26
Dependent Claim
34 words
The apparatus according to claim 21, wherein the repetition rate of the train of light pulses is set at a level substantially above the frequency of the AC power supply for the reproducing apparatus.
Claim 27
Dependent Claim
30 words
The apparatus according to claIm 21, wherein said photodetecting means includes means adapted to detect light from the copy sheet includes a bandpass filter tuned to said predetermined repetition rate.
Claim 28
Dependent Claim
24 words
The apparatus according to claim 23, including a peak detector for converting the AC output of said bandpass filter to provide a DC output.
Claim 29
Dependent Claim
26 words
The apparatus according to claim 19, including a second photodetecting means placed within the zone of reflection for detecting the light reflected from the photosensitive plate.
Claim 30
Dependent Claim
20 words
The apparatus according to claim 20, said means for applying a light is adapted to apply a focused light beam.
Claim 31
Dependent Claim
18 words
The apparatus according to claim 19, said means for applying a light beam is a laser light source.
Claim 32
Dependent Claim
37 words
The apparatus according to claim 27, wherein said light beam applying means includes means for modulating the light beam so that a train of light of a predetermined frequency is applied to the surface of said plate.
Claim 33
Independent Claim
70 words
A method of detecting presence of a medium that reflects an incident light, comprising the steps of: applying onto said medium a light beam pulsed at a predetermined repetition rate, photoelectrically detecting the light reflected from said medium, generating a train of electrical signal pulses representing the detected light, and filtering said train of electrical signal pulses to tune out noise signals therefrom, whereby the method is rendered noise immune.
Claim 34
Independent Claim
70 words
A method of detecting presence of a medium that reflects an incident light, comprising the steps of: applying onto said medium a light beam pulsed at a predetermined repetition rate, photoelectrically detecting the light reflected from said medium, generating a train of electrical signal pulses representing the detected light, and filtering said train of electrical signal pulses to tune out noise signals therefrom, whereby the method is rendered noise immune.
Claim 35
Dependent Claim
90 words
The method according to claim 29, wherein said method is adapted for detecting a substrate member having a planar reflecting surface that reflects incident light and wherein said medium being detected is a nonplanar sheet member that may be placed on said substrate member and that scatters or diffuses the incident light, including the step of; directing the incident light beam at a predetermined angle of incidence; and positioning photoelectrically detecting means at an angle of reflection within the zone of reflection for detecting the presence of said substrate member.
Claim 36
Dependent Claim
39 words
The method according to claim 30, including the step of positioning a photodetecting means outside of the zone of reflection for detecting the scattered or diffused light thereby detecting the presence of the sheet member on said substrate member.
Claim 37
Dependent Claim
21 words
The method according to claim 30 including the steps of directing the incident light beam at an angle of about 57*.
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) | 1977-08-26 | 1978-02-25 | 1978-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-26 | 1982-02-25 | 1982-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-26 | 1986-02-25 | 1986-08-27 | $7700.00 | Window Closed / Lapsed |