Supports: cabinet structure – Arrangements of plural cabinets – Relatively movable
Patent
1991-05-08
1992-06-16
Falk, Joseph
Supports: cabinet structure
Arrangements of plural cabinets
Relatively movable
A47B 8800
Patent
active
051219751
ABSTRACT:
A control circuit for continually testing a photoelectric detector. The detector includes a light source, and a photoelectric receiver having a predetermined drop-out time, attached to a movable storage carriage, spaced apart and substantially sightaligned. The carriage has a reversible electric motor which is controlled by the control circuit, including at least two relays, the contacts of which are connected in series so that the contacts of both must be closed in order for the motor to be energized. The relay drop-out time is substantially longer than the receiver drop-out time. In the circuit, an inverter is connected between the second coil and the light source. This inverter inverts signals received from the second coil and passes them to the light source so that receipt of a signal at the receiver causes the light source to turn off, in turn causing a loss of signal at the receiver, resulting in the light source turning on. An oscillation is thus established which passses through each component of the monitoring circuit and the detector. The drop-out time of the relays is long enough that the relays stay closed unless the oscillation is stopped, either by a failure of the monitoring circuit or light source or receiver, or by the light beam being broken. In either case, one or both of the relays opens, disabling the carriage from moving.
REFERENCES:
patent: 2851660 (1958-09-01), Tobin et al.
patent: 4259592 (1988-07-01), Dahnert
patent: 4745516 (1988-05-01), Griffin
Falk Joseph
Spacesaver Corporation
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