JPH02173532A - Chromaticity meter - Google Patents

Abstract

PURPOSE:To simplify structure and to miniaturize the meter by irradiating a colorimetric object with light, successively receiving the scattered light by an optical sensor and mutually operating three outputs from the optical sensor. CONSTITUTION:Light emitting diodes 2-4 respectively having emission spectrum approximate to color matching functions bar X(or bar X1), bar Y and bar Z are arranged so that the colorimetric object 1 is irradiated through a hole 6 formed on the lower part of a housing 5. The optical sensor 7 receives the scatted light from the surface of the object 1 and outputs an optical current in proportion to the intensity of the scattered light. Then, it has sensitivity in all the wavelength areas of the color matching functions. An electronic circuit part 8 is a power source for the diodes 2-4 and includes a control circuit and an amplification circuit etc. By successively lighting the diodes 2-4 for a short time, the object 1 is irradiated with the light and the sensor 7 successively receives the scattered light from the object 1. The three outputs from the sensor 7 which are equivalent to three stimulus values are mutually operated to obtain the chromaticity of the object 1.

Description

[Detailed description of the invention] (b) Industrial application field This invention includes 9 paper, cloth, plastics, and paint.

Related to colorimeter for measuring the color of various daily necessities, plants, skin, etc.

(B) Conventional techniques Methods for measuring the color of objects can be broadly divided into spectral colorimetry and stimulus value direct reading methods (see JIS Z 8722 1 Object Color Measuring Method). Devices using spectrophotometric methods generally have excellent accuracy, but are large and expensive. On the other hand, devices using the direct reading method of stimulus values are generally small and inexpensive, but have the following problems.

(1) In recent years, three optical sensors with mutually different wavelength sensitivity characteristics are often used as optical sensors for photoelectric colorimeters used in devices. Their spectral sensitivities are the intersection of color matching functions, 9. Although the approximation is made to z (in many cases, the wavelength part ZI is longer than the wavelength of light 500 nm), there is a large error. Therefore, accuracy is low.

(2) Devices that use incandescent lamps such as halogen lamps as light sources consume a lot of power and are difficult to miniaturize. Devices that use discharge tubes such as xenon lamps require high voltage generation circuits, and also require electrostatic shielding or electromagnetic shielding to prevent electrical noise caused by discharge from having a negative effect on electronic circuits such as amplifiers. They guide light to separate the light source from the electronic circuit.

(C) Problems to be Solved by the Invention The present invention is a device that solves the problem in item (2) of the problems of the device using the above-mentioned method of direct reading of stimulus values.

(d) Means for Solving the Problems An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing an example of a combined structure of a light source and an optical sensor in this device, where (a) is a plan sectional view and (h) is a vertical view. 1 is an object to be measured. 2゜3 and 4 are color matching functions or (or ma), respectively.

It is a light emitting diode having an emission spectrum similar to that of S'lX, and is arranged so as to irradiate the colorimetric object 1 through a hole 6 provided in the lower part of the outer casing 5. Reference numeral 7 denotes an optical sensor that receives scattered light from the surface of the colorimetric object 1 and outputs a photocurrent proportional to its intensity, and is sensitive to the wavelength range of all 9 color matching functions R, V+'f. An electronic circuit section 8 includes a power source for the light emitting diodes, a control circuit for sequentially turning them on and off according to a program, an amplifier circuit for amplifying the output photocurrent of the optical sensor, and the like.

(E) The light-emitting diodes 2, 3, and 4 are sequentially turned on for a short time to irradiate the colorimetric object 1 with light, and the scattered light from the colorimetric object 1 is sequentially received by the optical sensor 7 and transmitted from this optical sensor. The chromaticity of the colorimetric object is determined by mutually calculating the three outputs corresponding to the tristimulus values.

(f) Effects of the Invention While devices using conventional stimulus value direct reading methods use one light source and three optical sensors, the device of this invention uses three light sources and one optical sensor. A light sensor is used. The light source is a light emitting diode and is lit for a short time, so the overall power consumption is extremely low and there is almost no electrical noise. Therefore, it is possible to realize a compact device with a simple structure.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of a combination structure of a light source and an optical sensor in a device according to the present invention, and (a) is a plan cross-sectional view;
(b) is a vertical view. 1... Colorimetric object, 2, 3.4...--Light emitting diode, 5... Outer casing, 6... Hole,
7... Optical sensor 8... Electronic circuit section (CS, N(S))

Claims (1)

[Claims] 1 Color matching function @x@ (or @x@_1), @y@, @
The light emitting diodes 2, 3, and 4 having emission spectra similar to z@ are sequentially turned on for a short time to irradiate the colorimetric object 1 with light, and the scattered light from the colorimetric object 1 is sequentially detected by the optical sensor 7. A colorimeter characterized in that the chromaticity of a colorimetric object 1 is determined by mutually calculating three outputs corresponding to tristimulus values from the optical sensor.