Radiant energy – Photocells; circuits and apparatus – Signal isolator
Reexamination Certificate
2000-07-03
2001-11-13
Kim, Robert H. (Department: 2882)
Radiant energy
Photocells; circuits and apparatus
Signal isolator
C250S221000, C250S222100, C340S425500, C340S426110
Reexamination Certificate
active
06316778
ABSTRACT:
This invention relates to a theft deterrent for an electronic device, in particular for an electronic device in the passenger compartment of a motor vehicle.
Electronic devices fitted into motor vehicle passenger compartments are often stolen. Some electronic devices such as radios have a visible component part necessary for the operation of the device such as a keypad, so that when the device is left unattended the visible component part can be removed, thereby making the device less attractive to thieves. However, such visible component parts can be expensive to produce, and electrical connections between the visible component part and the device may corrode or otherwise deteriorate over time.
It is an object of the invention to provide a more reliable and economic removable visible component in an electronic device for a motor vehicle passenger compartment.
According the invention, there is provided an electronic device, comprising an accessible surface with a recess, a security bezel having a light pipe, the bezel being removably seated in the recess, and a light source and a light detector spaced apart within the recess, so that when the bezel is removed from the recess there is no optical path between the light source and the light detector, and when the bezel is seated in the recess the bezel provides an optical path through the light pipe between the light source and the light detector, wherein the device includes circuitry by which the operation of the electronic device is at least partially disabled when light from the light source does not reach the detector.
Because there need be no electrical contact between the electronic device and the bezel, problems of wear associated with such contacts are alleviated.
For simplicity, the light pipe may be a unitary light pipe, thereby avoiding the need for additional light coupling means at the ends of the light pipe.
Preferably, the bezel is substantially flush with the accessible surface when the bezel is seated in the recess.
The optical path provided by the bezel when it is seated in the recess will guide light from the light source to the detector. A sensor circuit may then sense when light from the light source reaches the light detector and produces a corresponding output signal indicating that the bezel is in the recess.
The output signal from the sensor circuit may be sent to a security circuit that at least partially disables the electronic device when a signal from the sensor circuit indicating that the bezel is seated in the recess is not received. Removing the bezel from the recess will prevent normal use of the electronic device, making it less useful and therefore less attractive to potential thieves.
The electronic device may be an audio device mounted in the instrument panel of a vehicle and the recess may be provided in a front panel of the audio device. To deter thieves, the bezel can be removed from the audio device when the audio device is left unattended in the vehicle.
The bezel may be removed from the vehicle and conveniently be carried in a clothes pocket when not mounted on the electronic device. If the bezel has an elongate pen-like shape, a clip may be provided on the bezel to attach it to a clothes pocket, in a similar fashion to a pen. This will make it easier to carry the bezel.
The light source and detector may respectively emit and detect visible light, but preferably they will emit and detect light in the infra-red part of the spectrum.
To ensure good optical coupling between the light pipe, the light source and the detector, the light pipe may terminate with end faces that respectively lie opposite to the light source and detector when the bezel is seated in the recess.
To prevent the light source from being in use unnecessarily, the device may comprise a sensor to sense when the bezel is seated in the recess so that the light source is only operational when the bezel is seated in the recess.
The light source may produce light of constant intensity, but in one embodiment, the light intensity produced by the light source changes with time according to a predetermined pattern and the sensor circuit only produces an output signal indicating that the bezel is seated in the recess if the light intensity reaching the detector changes with time according to the predetermined cycle. This prevents an unauthorized person from enabling the device by directing a continuous light source towards the detector, and also prevents the device from being enabled by background light.
To provide further deterrence to a potential thief, an additional light source may be provided that produces pulses of visible light when the bezel is not seated in the recess. Preferably, the additional light sources will be fixedly mounted in the recess to draw attention to the absence of the bezel.
REFERENCES:
patent: 4286305 (1981-08-01), Pilat et al.
patent: 4447123 (1984-05-01), Page et al.
patent: 6068627 (2000-05-01), Orszulak et al.
patent: 6201234 (2001-03-01), Chow et al.
patent: 6217182 (2001-04-01), Shepherd et al.
Chapman Simon
Goodman Gary
Johnston Malcolm
Ho Allen C.
Kim Robert H.
Shelton Larry I.
Visteon Global Technologies Inc.
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