EP0019478A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Apparatus and method for indicating a colour change of an object
Assignee: FIFE REGIONAL COUNCIL
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Filing: 1980-05-19
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Granted: —
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Expires: 2000-05-19
Abstract
Abstract An incident light beam from a light source (7) is guided by a light guide (11) onto the skin surface (5). Infra-red radiation is removed from the reflected beam by a filten20 located between the skin surface and two phototransistors (14, 15). The phototransistors (14, 15) detect the reflected light and has red and blue filters respectively. The outputs of the phototransistors are compared in a differential amplifier (27) and the differential amplifier output signal (29) is adjusted to zero by an offset bias circuit (28) for no colour change. When the surface changes colour the red and blue optical filters pass different amount of light and a difference is produced between the phototransistor outputs. This difference is amplified by the differential amplifier to provide an output signal representative of the colour change of the surface.
Inventors
- 👤 William Joseph Reilly
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 21:13
CPC Classifications
A; A61; A61B; A61B5/00; A61B5/68; A61B5/6801; A61B5/683; A61B5/6832; A61B5/6833; A61B5/0059; A61B5/44; A61B5/441; A61B5/48; A61B5/486; G; G01; G01J; G01J3/00; G01J3/46; G01J3/50; G01J3/51; G01J3/513
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
66 words
Apparatus for indicating the change in colour of a surface, comprising an incident light source for illuminating the surface, at least one light detector for detecting light reflected from the surface, means for providing a reference signal, and means for comparing the light reflected from the surface with the reference signal whereby when the surface changes colour a signal indicative of said colour change is produced.
Claim 2
Dependent Claim
66 words
Apparatus for indicating the change in colour of a surface, comprising an incident light source for illuminating the surface, at least one light detector for detecting light reflected from the surface, means for providing a reference signal, and means for comparing the light reflected from the surface with the reference signal whereby when the surface changes colour a signal indicative of said colour change is produced.
Claim 3
Dependent Claim
19 words
Apparatus as claimed in claim 1 wherein said means for providing a reference signal is a constant voltage source.
Claim 4
Dependent Claim
23 words
Apparatus as claimed in claim 1 wherein said means for providing a reference signal is a light detector, the apparatus having two detectors.
Claim 5
Dependent Claim
17 words
Apparatus as claimed in claim 2 wherein the detector has a light filter for filtering reflected light.
Claim 6
Dependent Claim
19 words
Apparatus as claimed in claim 3 where one or both detectors has a light filter for filtering reflected light.
Claim 7
Dependent Claim
20 words
Apparatus as claimed in claim 5 wherein one detector has a red filter, the other detector having a blue filter.
Claim 8
Dependent Claim
22 words
Apparatus as claimed in any preceding claim wherein an infra-red light filter is located between the surface and the or each detector.
Claim 9
Dependent Claim
20 words
Apparatus as claimed in any preceding claim wherein an infra-red filter is located between the light source and the surface.
Claim 10
Dependent Claim
27 words
Apparatus as claimed in any preceding claim wherein the means for comparing the light reflected from the surface with the reference signal is a differential amplifier circuit.
Claim 11
Dependent Claim
30 words
Apparatus as claimed in claim 9 wherein the signal indicative of a colour change is a modulated frequency signal in the audible range and is preferably connected to a loudspeaker.
Claim 12
Dependent Claim
21 words
Apparatus as claimed in claim 9 wherein the signal indicative of a colour change is a varying direct current (d.c.) shift.
Claim 13
Independent Claim
63 words
A method of indicating a colour change of a surface comprising, illuminating the surface with incident light, detecting light reflected from the surface which is indicative of the colour of the surface, adjusting the detected light signal to give a reference signal, continuously comparing the detected light reflected with the reference signal to provide an output signal indicative of a surface colour change.
Claim 14
Independent Claim
63 words
A method of indicating a colour change of a surface comprising, illuminating the surface with incident light, detecting light reflected from the surface which is indicative of the colour of the surface, adjusting the detected light signal to give a reference signal, continuously comparing the detected light reflected with the reference signal to provide an output signal indicative of a surface colour change.
References Cited (Backward Citations)
No citation records indexed.
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