Abstract Described is a digital light meter formed from devices, such as silicon four-layer switches, each of which can be triggered into conduction by incident photons. The intensity of the photons necessary to trigger a switch into conduction is dependent upon the magnitude of a bias voltage applied across the device. By providing a plurality of switches, all exposed to the same source of incident light, and by biasing the respective switches with progressively decreasing bias voltages, the number of switches triggered into conduction will increase as the light intensity increases. The invention additionally includes means for automatically terminating the flow of current through each switch when the intensity of the incident photons falls below the triggering level for that switch.
In a light meter, the combination of a plurality of twoterminal devices of the type which normally act as open circuits but which can be triggered into conduction by incident photons, the intensity of the photons necessary to trigger each device being a function of a bias voltage applied across the two terminals of the device, and means for applying bias voltages of different magnitudes across the respective devices in the plurality of devices such that the respective devices will be triggered into conduction at different photon intensity levels.
Claim 2
Dependent Claim
89 words
In a light meter, the combination of a plurality of twoterminal devices of the type which normally act as open circuits but which can be triggered into conduction by incident photons, the intensity of the photons necessary to trigger each device being a function of a bias voltage applied across the two terminals of the device, and means for applying bias voltages of different magnitudes across the respective devices in the plurality of devices such that the respective devices will be triggered into conduction at different photon intensity levels.
Claim 3
Dependent Claim
12 words
The combination of claim 1 wherein said devices comprise four-layer semiconductor switches.
Claim 4
Dependent Claim
13 words
The combination of claim 1 wherein said devices comprise silicon four-layer PNPN switches.
Claim 5
Dependent Claim
13 words
The combination of claim 1 wherein said devices comprise silicon four-layer NPNP switches.
Claim 6
Dependent Claim
39 words
The combination of claim 1 wherein the means for applying bias voltages across the respective devices comprises a single source of direct current potential, and resistors of different magnitudes connecting said source of bias potential to the respective devices.
Claim 7
Dependent Claim
25 words
The combination of claim 1 wherein each of said resistors is connected in series with an associated one of said devices and a neon lamp.
Claim 8
Dependent Claim
28 words
The combination of claim 6 wherein said resistors are interconnected by means of capacitors, each capacitor forming the capacitive component of a relaxation oscillator with its associated resistor.