Radiation-sensitive switching circuits
AssigneeThe Lucas Electrical Company Limited
InventorsJohn Howard Moore, Charles Peter Cockshott
Life of this patent
Estimating the term…
Abstract
A radiation-sensitive switching circuit has a light emitting diode which supplies light to a photo-transistor, the light being interrupted from time to time. When the photo-transistor is illuminated, current builds up and when this current reaches a predetermined value, a trigger circuit changes state. The peak output of the photo-transistor is measured and the trigger circuit is arranged to change state when the output of the device is a set proportion of the peak output, so as to allow for aging of the components.
Claims5
A radiation-sensitive switching circuit comprising in combination a radiation source, a radiation-sensitive device which conducts when exposed to the radiation source, a control member positioned between the source and device and serving to expose the device to the source at predetermined instants of time, a capacitive storage means, an emitter follower amplifier, circuit means connecting the device with the amplifier and capacitive storage means, said capacitive storage means being connected in the emitter circuit of said amplifier and thereby measuring the peak output of the device, potential dividing means connected to said storage means to develop a signal proportional to said peak output, and a trigger circuit having a comparator means coupled to said potential dividing means and to said device, said comparator means being responsive to establish a trigger output signal in response to the output from the device being a preselected proportion of said peak output.
Dependencies are inferred from the claim text.