US3826569A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Exposure safeguarding device for photocopying machine
Assignee: Canon Inc
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Filing: 1973-02-27
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Granted: 1974-07-30
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Expires: 1993-02-27
Abstract
Abstract This invention provides a safety device for preventing under exposure in a photocopying device. The device includes a sensitive element for detecting the temperature around the exposure light source, and delay means for varying the delay time according to the temperature difference detected by the sensitive element.
Inventors
- 👤 H Sakamaki
- 👤 Y Kimura
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 19:50
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/04; G03G15/04036; G03G15/043
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
160 words
In an electrophotographic copying machine of the type comprising an original holder, an exposure light source, a sensitive member upon which is reproduced the image of an original placed upon said original holder, an optical system for focusing said original upon said sensitive member, processing means disposed around said sensitive means for producing a copy of said original, means for driving said machine to effect copy processing, and means for controlling energization of said driving means, an improvement comprising an exposure safeguarding device having a temperature sensing element for sensing the temperature around said exposure light source, time-delay means coupled to said temperature sensing element and having an output for producing a signal after a delay time which commences with actuation of said exposure light source, and which changes in response to temperature variations sensed by said temperature sensing element, and means coupled between said time-delay means output and said driving means for controlling the energization of said driving means.
Claim 2
Dependent Claim
160 words
In an electrophotographic copying machine of the type comprising an original holder, an exposure light source, a sensitive member upon which is reproduced the image of an original placed upon said original holder, an optical system for focusing said original upon said sensitive member, processing means disposed around said sensitive means for producing a copy of said original, means for driving said machine to effect copy processing, and means for controlling energization of said driving means, an improvement comprising an exposure safeguarding device having a temperature sensing element for sensing the temperature around said exposure light source, time-delay means coupled to said temperature sensing element and having an output for producing a signal after a delay time which commences with actuation of said exposure light source, and which changes in response to temperature variations sensed by said temperature sensing element, and means coupled between said time-delay means output and said driving means for controlling the energization of said driving means.
Claim 3
Dependent Claim
28 words
An exposure safeguarding device as defined in claim 1 wherein said temperature sensing element comprises switch means adapted to turn on or off at a predetermined threshold temperature.
Claim 4
Dependent Claim
40 words
An exposure safeguarding device as defined in claim 2 wherein said time-delay means comprises a time constant circuit consisting of resistor means and capacitor means and said temperature sensing element is connected in parallel with one of said resistor means.
Claim 5
Dependent Claim
17 words
An exposure safeguarding device as defined in claim 2 wherein said temperature sensing element is a thermostat.
Claim 6
Dependent Claim
27 words
An exposure safeguarding device as defined in claim 1 wherein said temperature sensing element comprises an element having a resistance which varies in response to temperature variations.
Claim 7
Dependent Claim
17 words
An exposure safeguarding device as defined in claim 5 wherein said temperature sensing element is a thermistor.
Claim 8
Dependent Claim
33 words
An exposure safeguarding device as defined in claim 5 wherein said time-delay means comprises a time constant circuit consisting of a series circuit including resistor means, capacitor means and said temperature sensing element.
Claim 9
Dependent Claim
101 words
An exposure safeguarding device as defined in claim 1 wherein said temperature sensing element comprises switch means adapted to turn on or off at a predetermined threshold temperature, said time-delay means comprises a time constant circuit including capacitor means and a plurality of resistor means and has said temperature sensing element connected in parallel with one of said resistor means, and wherein said energization control means includes an N-gate thyristor connected to said time-delay means output for actuation to control said driving means, and said thyristor having principal conducting electrodes coupled to said capacitor means to provide a discharge path therefor.
References Cited (Backward Citations)
US3330180A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-07-29 | 1978-01-28 | 1978-07-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-07-29 | 1982-01-28 | 1982-07-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-07-29 | 1986-01-28 | 1986-07-30 | $7700.00 | Window Closed / Lapsed |