Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
115 words
Apparatus for receiving voltage from a power supply and for producing a periodic electrical output signal whose average value is proportional to the ambient light level and independent of fluctuations in the power supply voltage, comprising: a photosensor circuit for producing an electrical signal proportional to the ambient light level and substantially independent of the power supply voltage; a ramp oscillator circuit for producing a periodic electrical signal having a ramp waveform whose amplitude is proportional to the power supply voltage; and an output circuit for comparing the photosensor signal to the ramp signal and producing a periodic output signal whose duty cycle is the portion of time the photosensor signal exceeds the ramp signal.
Claim 2
Dependent Claim
115 words
Apparatus for receiving voltage from a power supply and for producing a periodic electrical output signal whose average value is proportional to the ambient light level and independent of fluctuations in the power supply voltage, comprising: a photosensor circuit for producing an electrical signal proportional to the ambient light level and substantially independent of the power supply voltage; a ramp oscillator circuit for producing a periodic electrical signal having a ramp waveform whose amplitude is proportional to the power supply voltage; and an output circuit for comparing the photosensor signal to the ramp signal and producing a periodic output signal whose duty cycle is the portion of time the photosensor signal exceeds the ramp signal.
Claim 3
Dependent Claim
61 words
The apparatus of claim 1, wherein the output circuit comprises: a latch circuit having a first input and having an output which produces said periodic output signal; and a first comparator having a first input connected to receive the photosensor signal, a second input connected to receive the ramp signal, and an output connected to the first input of the latch.
Claim 4
Dependent Claim
52 words
The apparatus of claim 2, wherein the output circuit further comprises: a second comparator having a first input connected to receive a reference voltage, a second input connected to receive the ramp signal, and an output; wherein the latch further includes a second input connected to the output of the second comparator.
Claim 5
Dependent Claim
32 words
The apparatus of claim 3, further comprising a light-emitting display connected to receive power from the periodic output signal, wherein the display produces a light output proportional to the periodic output signal.
Claim 6
Dependent Claim
85 words
Apparatus for controlling the brightness of a light-emitting display having a plurality of display elements which are sequentially time multiplexed at a certain frequency, comprising: means for driving each display element with a periodic electrical signal; means for controlling the duty cycle of the periodic electrical signal to control the brightness of each display element; and means for synchronizing the frequency of the periodic signal driving each said display element to a multiple of the frequency at which the display elements are sequentially time multiplexed.
Claim 7
Dependent Claim
85 words
Apparatus for controlling the brightness of a light-emitting display having a plurality of display elements which are sequentially time multiplexed at a certain frequency, comprising: means for driving each display element with a periodic electrical signal; means for controlling the duty cycle of the periodic electrical signal to control the brightness of each display element; and means for synchronizing the frequency of the periodic signal driving each said display element to a multiple of the frequency at which the display elements are sequentially time multiplexed.