Access control system with energy-saving optical token presence sensor system
First Claim
1. An identification token reading system comprising:
- an identification token reader configured to read a token when energized; and
an object presence sensor includinga radiation emitter configured to emit a first radiation and define a field of view the radiation emitter generating a synchronization signal;
a radiation receiver configured to receive a second radiation reflected from an object positioned within the field of view, the receiver generating a first signal;
a band-pass filter coupled to the receiver and operable to pass a portion of the first signal having a signal level, the synchronization signal operable to coordinate the timing of the band-pass filter and the radiation emitter; and
a comparator configured to receive the portion of the first signal and generate a second signal when the signal level increases above a first predetermined level and, to generate a third signal when the signal level falls below a second predetermined level that is lower than the first predetermined level and is greater than zero, the identification token reader being energized in response to receipt of the second signal and de-energized in response to receipt of the third signal.
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Accused Products
Abstract
An access control system having an energy-saving optical presence sensor system is provided. The access control system includes a relatively lower operating power object presence sensor system for optically sensing the presence of a token as well in addition to a relatively higher operating power token reader for reading the token. The token reader remains unpowered until a token is detected by the object presence sensor system, which is preferably always powered. Once an object is detected by the object presence sensor system, power is supplied to the token reader and the token is read. After the token has been read, power ceases to be applied to the token reader, although the object presence sensor remains powered.
56 Citations
23 Claims
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1. An identification token reading system comprising:
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an identification token reader configured to read a token when energized; and an object presence sensor including a radiation emitter configured to emit a first radiation and define a field of view the radiation emitter generating a synchronization signal; a radiation receiver configured to receive a second radiation reflected from an object positioned within the field of view, the receiver generating a first signal; a band-pass filter coupled to the receiver and operable to pass a portion of the first signal having a signal level, the synchronization signal operable to coordinate the timing of the band-pass filter and the radiation emitter; and a comparator configured to receive the portion of the first signal and generate a second signal when the signal level increases above a first predetermined level and, to generate a third signal when the signal level falls below a second predetermined level that is lower than the first predetermined level and is greater than zero, the identification token reader being energized in response to receipt of the second signal and de-energized in response to receipt of the third signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A locking mechanism comprising:
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an emitter configured to selectively emit a first radiation; an optical detector configured to detect the presence of an object within a field of view at least partially based on reflected radiation from the emitter and to generate a first signal having a signal strength that is related to the proximity of the object to the detector; an amplifier with a switched offset null and positioned to receive the first signal and output an amplified first signal having an amplified signal strength; a sensor configured to receive the first signal and to generate one of a second signal when the amplified signal strength increases past a first predetermined level and a third signal when the amplified signal strength falls below a second predetermined level, the emitter, the sensor, and the amplifier synchronized such that the amplifier is activated and the amplified first signal is zeroed immediately prior to activating the emitter and emitting a subsequent pulse of the first radiation; an identification token reader configured to energize in response to the second signal and de-energize in response to the third signal, when energized, the identification token reader configured to read data from the object; a timer configured to de-energize the identification token reader in response to the passage of a predetermined amount of time and the failure to read data from the object; and a lock mechanism configured to disengage a lock in response to the read data from the object. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19)
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20. An identification token reading system comprising:
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a power supply configured to supply power; an emitter coupled to the power supply, and configured to receive at least a portion of the power and to selectively emit an emitted signal using the at least a portion of the power and to generate a synchronization signal; a receiver, having a field of view, and configured to receive a reflected signal when an object is present in the field of view to reflect the emitted signal; a band-pass filter coupled to the receiver and operable to pass a portion of the reflected signal having a signal level that varies between a first level and a second level when the emitter is emitting a signal, the synchronization signal operable to coordinate the timing of the band-pass filter and the radiation emitter; a circuit coupled to the receiver and configured to generate a first signal when the signal level rises above a third signal level and to generate a second signal when the signal level falls below a fourth level, the fourth level being below the third level; and a token reader coupled to the circuit and configured to switch to an ON state in response to the first signal and an OFF state in response to the second signal, when in the ON state, the token reader configured to receive power from the power supply to read the object. - View Dependent Claims (21, 22, 23)
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Specification