US6479810B1
Expired / Lapsed
US
⏱️ 0.0 years remaining
Light sensor system and a method for detecting ambient light
Assignee: Visteon Global Technologies Inc
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Filing: 2000-08-18
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Granted: 2002-11-12
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Expires: 2020-08-18
Abstract
Abstract A light sensor assembly 10 and a method for detecting ambient light 100 which logarithmically amplifies a first signal which is representative of the certain amount of sensed light and a second offset signal and which adds the logarithmically amplified signals to a voltage signal, thereby allowing an accurate signal to be produced which indicative of the sensed amount of light by use of only a positive type electrical power supply and which is effective to allow the output signal to fall within the relatively narrow operating range of a cost effective digital to analogue converter.
Inventors
- 👤 Paul Frederick Luther Weindorf
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:01
CPC Classifications
G; G01; G01J; G01J1/00; G01J1/42; G01J1/4204; G01J1/10; G01J1/44
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
177 words
A light sensor assembly comprising: a photodiode which detects a certain amount of light and, in response to said detected certain amount of light, generates an electrical current signal; a first amplifier which is coupled to said photodiode; a logarithmic amplifier circuit which is coupled to said photodiode and to said first amplifier; a second amplifier which is coupled to said logarithmic amplifier circuit; and a power supply which only provides a voltage signal having an amplitude which is greater than zero and wherein said second amplifier causes an offset current signal to flow through said logarithmic amplifier, effective to cause said photodiode to only operate in a photoamperic mode and wherein said logarithmic amplifier produces a voltage output signal which is communicated to said second amplifier, said second amplifier further receiving an offset voltage signal which cooperates with said received voltage output signal to cause said second amplifier to produce an output signal which is representative of said detected certain amount of light, said output signal being constrained to vary only between zero and five volts.
Claim 2
Dependent Claim
177 words
A light sensor assembly comprising: a photodiode which detects a certain amount of light and, in response to said detected certain amount of light, generates an electrical current signal; a first amplifier which is coupled to said photodiode; a logarithmic amplifier circuit which is coupled to said photodiode and to said first amplifier; a second amplifier which is coupled to said logarithmic amplifier circuit; and a power supply which only provides a voltage signal having an amplitude which is greater than zero and wherein said second amplifier causes an offset current signal to flow through said logarithmic amplifier, effective to cause said photodiode to only operate in a photoamperic mode and wherein said logarithmic amplifier produces a voltage output signal which is communicated to said second amplifier, said second amplifier further receiving an offset voltage signal which cooperates with said received voltage output signal to cause said second amplifier to produce an output signal which is representative of said detected certain amount of light, said output signal being constrained to vary only between zero and five volts.
Claim 3
Dependent Claim
16 words
The light sensor assembly of claim 1 wherein said photodiode comprises an omnidirectional fresnel optic portion.
Claim 4
Dependent Claim
17 words
The light sensor assembly of claim 1 wherein said first amplifier comprises a dual operational rail-to-rail amplifier.
Claim 5
Dependent Claim
17 words
The light sensor assembly of claim 3 wherein said second amplifier comprises a dual operational rail-to-rail amplifier.
Claim 6
Dependent Claim
29 words
The light sensor assembly of claim 1 wherein said logarithmic amplifier circuit comprises a first transistor and a second transistor, and wherein said first transistor further comprises an emitter.
Claim 7
Dependent Claim
19 words
The light sensor assembly of claim 5 wherein said first and said second transistors are substantially matched and isothermal.
Claim 8
Dependent Claim
27 words
The light sensor assembly of claim 5 wherein said first amplifier substantially maintains about zero volts of voltage across said photodiode by the use of negative feedback.
Claim 9
Dependent Claim
62 words
The light sensor assembly of claim 7 wherein said first amplifier further comprises a positive terminal and a negative terminal and wherein said first amplifier controls said emitter such that the current flows through said first transistor to allow the voltage at said negative terminal of said first amplifier to substantially equal the voltage at said positive terminal of said first amplifier.
Claim 10
Dependent Claim
27 words
The light sensor assembly of claim 1 wherein said photodiode comprises a silicon temperature sensor, effective to substantially reduce the temperature sensitivity of said light sensor assembly.
Claim 11
Independent Claim
180 words
A method for detecting ambient light by use of a light sensor assembly, said method comprising the steps of: providing a power supply which only provides a voltage signal having an amplitude which is greater than zero; providing a photodiode; causing said photodiode to detect a certain amount of light; providing a first amplifier; coupling said first amplifier to said photodiode; providing a logarithmic amplifier circuit; coupling said logarithmic amplifier circuit to said photodiode and to said first amplifier; providing a second amplifier; coupling said second amplifier to said logarithmic amplifier circuit; causing an offset current signal from said second amplifier to flow through said logarithmic amplifier; causing said logarithmic amplifier to produce a voltage output signal; communicating said voltage output signal to said second amplifier; causing said second amplifier to receive an offset voltage signal; causing said offset voltage signal to cooperate with said voltage output signal; causing said second amplifier to produce an output signal which is representative of said detected certain amount of light; and constraining said output signal to vary only between zero and five volts.
Claim 12
Independent Claim
180 words
A method for detecting ambient light by use of a light sensor assembly, said method comprising the steps of: providing a power supply which only provides a voltage signal having an amplitude which is greater than zero; providing a photodiode; causing said photodiode to detect a certain amount of light; providing a first amplifier; coupling said first amplifier to said photodiode; providing a logarithmic amplifier circuit; coupling said logarithmic amplifier circuit to said photodiode and to said first amplifier; providing a second amplifier; coupling said second amplifier to said logarithmic amplifier circuit; causing an offset current signal from said second amplifier to flow through said logarithmic amplifier; causing said logarithmic amplifier to produce a voltage output signal; communicating said voltage output signal to said second amplifier; causing said second amplifier to receive an offset voltage signal; causing said offset voltage signal to cooperate with said voltage output signal; causing said second amplifier to produce an output signal which is representative of said detected certain amount of light; and constraining said output signal to vary only between zero and five volts.
Claim 13
Dependent Claim
42 words
The method of claim 10 wherein said step of causing said photodiode to detect a certain amount of light further comprises the step of causing said photodiode to generate an electrical current signal in response to said detected certain amount of light.
Claim 14
Dependent Claim
74 words
The method of claim 10 wherein said step of providing a second amplifier further comprises the steps of: providing a first resistor; providing a second resistor; providing a third resistor; coupling said first resistor to the negative terminal of said second amplifier; coupling said second resistor to the positive terminal of said second amplifier; coupling said third resistor to said first and said second resistors; and coupling said third resistor to said power supply.
Claim 15
Dependent Claim
93 words
The method of claim 12 further comprising the steps of: providing a fourth resistor; providing a fifth resistor; providing a sixth temperature dependant resistor; providing a seventh resistor; coupling said fourth resistor to said positive terminal of said second amplifier; coupling said fifth resistor to said positive terminal of said second amplifier between said fourth resistor and said second resistor; coupling said sixth temperature dependant resistor to said logarithmic amplifier and to said fourth resistor; and coupling said seventh resistor to said logarithmic amplifier and to said negative terminal of said second amplifier.
References Cited (Backward Citations)
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