Patent US3912924A successfully refreshed from Google Patents.
US3912924A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Machine safety control
Assignee: LINK ELECTRIC AND SAFETY CONTROL CO
•
Filing: 1973-11-07
•
Granted: 1975-10-14
•
Expires: 1993-11-07
Abstract
Abstract Multiple photocells employing an OR-gate arrangement avoid injury to machine operators.
Inventors
- 👤 Jr James G Barrett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:55
CPC Classifications
F; F16; F16P; F16P3/00; F16P3/12; F16P3/14; F16P3/144; G; G01; G01V; G01V8/00; G01V8/10; G01V8/20
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
167 words
A photoelectric safety mechanism for machine operators comprising a plurality of photocells disposed at one side of a machine work area, a single source of light disposed on the opposite side of said work area for energizing said plurality of photocells, an OR-gate circuit electrically connected to said plurality of photocells and comprising a plurality of Darlington amplifiers, said photocells being responsive to said single source of light and controlling the current flow in said OR-gate circuit, said OR-gate circuit being responsive to and actuated by interruptions in one or more beams projected from said light source, said one or more beams being collimated to said photocells by a plurality of slots in a member, each slot being associated with a single one of said photocells, and means connecting said OR-gate circuit controlling the stopping and starting of said machine, and means being operable to prevent injury to an operator of said machine by said machine in response to said interruption of said one or more beams.
Claim 2
Dependent Claim
167 words
A photoelectric safety mechanism for machine operators comprising a plurality of photocells disposed at one side of a machine work area, a single source of light disposed on the opposite side of said work area for energizing said plurality of photocells, an OR-gate circuit electrically connected to said plurality of photocells and comprising a plurality of Darlington amplifiers, said photocells being responsive to said single source of light and controlling the current flow in said OR-gate circuit, said OR-gate circuit being responsive to and actuated by interruptions in one or more beams projected from said light source, said one or more beams being collimated to said photocells by a plurality of slots in a member, each slot being associated with a single one of said photocells, and means connecting said OR-gate circuit controlling the stopping and starting of said machine, and means being operable to prevent injury to an operator of said machine by said machine in response to said interruption of said one or more beams.
Claim 3
Dependent Claim
112 words
The safety mechanism of claim 1 wherein the OR-gate circuit comprises a plurality of Silicon-Darlington amplifiers whereby an input signal results from a change of resistance which causes a change of voltage upon said interruption of one or more beams, said interruption of said one or more beams causing a decrease in the light energy which impinges on said one or more photocells, said decrease increasing the resistance of said one or more photocells and causing an increase in the voltage across said one or more photocells, thereby causing an increase in the input voltage of said plurality of Silicon-Darlington amplifiers and causing said Silicon-Darlington amplifiers to stop operation of said machine.
Claim 4
Dependent Claim
34 words
The safety device of claim 2 wherein a switch automatically stops the operation of the machine upon receipt of a signal of said increase in the input voltage of said plurality of Silicon-Darlington amplifiers.
References Cited (Backward Citations)
US2758712A
Cited
US3478220A
Cited
US3624454A
Cited
US3704396A
Cited
US3746863A
Cited
US3789384A
Cited
US3805061A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-13 | 1979-04-14 | 1979-10-14 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-13 | 1983-04-14 | 1983-10-14 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-13 | 1987-04-14 | 1987-10-14 | $7700.00 | Window Closed / Lapsed |