US3728023A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure control for electrostatic copiers
Assignee: AB Dick Co
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Filing: 1971-10-14
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Granted: 1973-04-17
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Expires: 1991-10-14
Abstract
Abstract An exposure control for contact copiers wherein an original document is moved on a path of travel first to an illumination intensity measuring and control station and thence to an exposure station. Illumination means are provided to direct a first quantum of light across the path of travel at the measuring and control station and a second quantum of light at the exposure station. Light intensity measuring and control means, including electrical circuity, are provided at the measuring and control station to sense the intensity of light passing through the original document and change the emitted intensity of the first quantum of light to provide a selected sensed intensity thereof. The emitted intensity of the second quantum of light is also changed directly proportional to the change in the emitted intensity of the first quantum. Means are also provided to maintain the emitted intensities while the original document is transferred from the measuring and control station to the exposure station.
Inventors
- 👤 P Stevko
- 👤 J Petrella
- 👤 G Dissauer
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:01
CPC Classifications
G; G03; G03B; G03B27/00; G03B27/72; G03B27/80
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
265 words
Apparatus for controlling the intensity of illumination to provide uniform exposure of a light sensitive copy sheet through an original document in a contact electrostatic copying apparatus wherein different types of original documents are copied comprising, means to establish a path of travel of said original document first to an illumination intensity measuring and control station and thence to a downstream exposure station whereat the original document is in superimposed relation with the copy sheet, illumination means disposed on one side of said path to direct a first quantum of light across said path of travel and through said original document at said measuring and control station and other illumination means disposed on one side of said path to direct a second quantum of light across said path of travel and through said original document at said exposure station, measuring and control means disposed on the opposite side of said path and positioned to intercept and measure the intensity of light from said first quantum as it passes through said original document and to produce a signal representative of the intensity of said light, means connected to the illumination means and responsive to said signal to change the emitted intensity of the light of said illumination means at said measuring and control station and change said second quantum of light proportional thereto to provide a preselected sensed intensity of light at said exposure station, and means to maintain the emitted intensities while said original document is being transferred from said measuring and control station to said exposure station and while maintained at said exposure station.
Claim 2
Dependent Claim
265 words
Apparatus for controlling the intensity of illumination to provide uniform exposure of a light sensitive copy sheet through an original document in a contact electrostatic copying apparatus wherein different types of original documents are copied comprising, means to establish a path of travel of said original document first to an illumination intensity measuring and control station and thence to a downstream exposure station whereat the original document is in superimposed relation with the copy sheet, illumination means disposed on one side of said path to direct a first quantum of light across said path of travel and through said original document at said measuring and control station and other illumination means disposed on one side of said path to direct a second quantum of light across said path of travel and through said original document at said exposure station, measuring and control means disposed on the opposite side of said path and positioned to intercept and measure the intensity of light from said first quantum as it passes through said original document and to produce a signal representative of the intensity of said light, means connected to the illumination means and responsive to said signal to change the emitted intensity of the light of said illumination means at said measuring and control station and change said second quantum of light proportional thereto to provide a preselected sensed intensity of light at said exposure station, and means to maintain the emitted intensities while said original document is being transferred from said measuring and control station to said exposure station and while maintained at said exposure station.
Claim 3
Dependent Claim
65 words
Apparatus as defined in claim 1 wherein said illumination means disposed to direct the quanta of light includes first and second lamps of similar emission characteristics each connectable to said measuring and control means, said first lamp being positioned to direct its illumination toward said illumination intensity measuring and control station and said second lamp being positioned to direct its illumination toward said exposure station.
Claim 4
Dependent Claim
28 words
Apparatus as defined in claim 1 wherein said illumination means includes a lamp of similar emission characteristics at each of said stations, said lamps being connected in parallel.
Claim 5
Dependent Claim
22 words
Apparatus as defined in claim 2 further characterized by means to vary the selected sensed intensity of said first quantum of light.
Claim 6
Dependent Claim
66 words
Apparatus as defined in claim 2 wherein said measuring and control means includes a photocell, said first quantum of light being adapted to control the resistance of said photocell, and said means to maintain the emitted intensities comprising a holding circuit including capacitance means adapted for coupling in circuit with said photocell, the charge on said holding circuit being responsive to the resistance of said photocell.
Claim 7
Dependent Claim
44 words
Apparatus as defined in claim 5 wherein said holding circuit is coupled in electrical circuit with said photocell by switch means, said switch means being automatically actuated to on condition by said original document when the latter is disposed at the first mentioned station.
Claim 8
Dependent Claim
41 words
Apparatus as defined in claim 6 wherein said switch means includes means for automatically actuating said switch means to off condition upon movement of said original document from said first mentioned station, to electrically uncouple said photocell from said holding circuit.
Claim 9
Dependent Claim
21 words
Apparatus as defined in claim 5 wherein said holding circuit is coupled in electrical circuit with said photocell by a diode.
Claim 10
Dependent Claim
13 words
Apparatus in accordance with claim 6 wherein said switch means includes relay means.
Claim 11
Dependent Claim
33 words
Apparatus in accordance with claim 5 including reset meanS electrically coupled to said holding circuit for resetting said holding circuit after completion of the exposure of said master sheet at said exposure station.
Claim 12
Dependent Claim
32 words
Apparatus in accordance with claim 10 wherein said reset means includes means to automatically reset said holding circuit upon movement of said master sheet away from said exposure station after exposure thereof.
Claim 13
Dependent Claim
38 words
Apparatus in accordance with claim 5 wherein said means to change the emitted intensity comprises amplifier means, firing circuit means and SCR means coupled in circuit with one another and with said holding circuit and said illumination means.
Claim 14
Dependent Claim
15 words
Apparatus in accordance with claim 12 wherein said amplifier means includes a two stage amplifier.
Claim 15
Dependent Claim
15 words
Apparatus in accordance with claim 12 wherein said firing circuit means includes a unijunction transistor.
References Cited (Backward Citations)
US2995978A
Cited
US3609038A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-04-16 | 1976-10-16 | 1977-04-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-04-16 | 1980-10-16 | 1981-04-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-04-16 | 1984-10-16 | 1985-04-17 | $7700.00 | Window Closed / Lapsed |