US3864565A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light amount integration means
Assignee: Pentax Corp
•
Filing: 1973-09-13
•
Granted: 1975-02-04
•
Expires: 1993-09-13
Abstract
Abstract A light receiving element is operative to provide an electrical signal representing the amount of light it is receiving. The element is connected between the source and gate of a groundedgate field effect transistor having its drain connected to provide current to a storage capacitor. A switching element connected to the source controls a charging operation whereby current provided to the capacitor develops across the capacitor a voltage proportional to the integral of the current and thereby also proportional to the amount of light received over a specific time duration.
Inventors
- 👤 Masahiro Kawasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 12:37
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/44; G01J1/46
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
133 words
Apparatus for measuring and indicating light amount, which comprises a field effect transistor having a source, a gate, and a drain, and arranged in a grounded-gate circuit configuration; a light receiving element which is connected between the gate and the source and which develops a signal proportional to the amount of light it is receiving; a capacitor connected to be charged by current flowing through the field effect transistor, and a switching element connected to the source of the field effect transistor for controlling a charging operation in which said signal causes current to flow through the field effect transistor to charge the capacitor across which there is developed a voltage proportional to the integral of the current and thereby also proportional to the amount of light received over a specific time duration.
Claim 2
Dependent Claim
133 words
Apparatus for measuring and indicating light amount, which comprises a field effect transistor having a source, a gate, and a drain, and arranged in a grounded-gate circuit configuration; a light receiving element which is connected between the gate and the source and which develops a signal proportional to the amount of light it is receiving; a capacitor connected to be charged by current flowing through the field effect transistor, and a switching element connected to the source of the field effect transistor for controlling a charging operation in which said signal causes current to flow through the field effect transistor to charge the capacitor across which there is developed a voltage proportional to the integral of the current and thereby also proportional to the amount of light received over a specific time duration.
Claim 3
Dependent Claim
14 words
Apparatus according to claim 1 wherein the light receiving element is a photo diode.
Claim 4
Dependent Claim
54 words
Apparatus according to claim 1 wherein the switching element is a junction transistor, and wherein the apparatus further includes a switch and a timing circuit for controlling the switching into conduction of the junction transistor so that there is a predetermined delay between the operation of the switch and switching of the junction transistor.
References Cited (Backward Citations)
US3442190A
Cited
US3568582A
Cited
US3602717A
Cited
US3563143A
Cited
US3657979A
Cited
US3673415A
Cited
US3691917A
Cited
US3678826A
Cited
US3736851A
Cited
US3712192A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |