JPS63182549A - Color sensor - Google Patents

Abstract

PURPOSE:To obtain a low-cost color sensor which discriminates the color of a body by light reflection by providing the sensor with plural photodetection parts, photodetecting reflected light through optical fibers which differ in wavelength dispersion characteristics, and performing color discrimination from the ratio of the respective quantities of photodetection. CONSTITUTION:Elements of the same standard are used as a photodetector 410 and circuits of the same standard are used for decision circuits 5 and 11; and a comparing circuit 12 detects the output ratio of the circuits 5 and 11. Simultaneously, it is compared with rate data corresponding to colors stored in the circuit 12 previously to determine a color, and the result is outputted from a circuit 7. Thus, the sensor is constituted, light from, for example, the element 3 is projected on the body 1 to be measured through an optical fiber for projection, and reflected light from it is photodetected by an optical fiber 8 which uses polycarbonate for its core and an optical fiber 8 which uses acrylic resin for its core. When the color of the body to be measured is blue, the reflected light becomes blue to cause a difference between the outputs of elements 4 and 10, but when the reflected light is red, the difference becomes small, so the color is easily decided.

Description

[Detailed Description of the Invention] [Summary] The present invention provides a color sensor that identifies the color of an object by reflecting light, in order to identify two or more colors at low cost.
The sensor has a plurality of light receiving sections, each receiving reflected light through optical fibers having different wavelength dispersion characteristics, and color identification is performed based on the ratio of the amounts of each received light.

[Industrial application field]

The present invention relates to a color sensor using optical fibers with different wavelength dispersion characteristics.

There are two types of color sensors: one that determines whether the desired color is a target color based on the difference in light reflectance depending on the color, and the other that determines based on the wavelength components of reflected light.

The former method is low in cost, but has low reliability, and it is difficult to judge multiple colors. The latter method is highly reliable and allows easy determination of multiple colors, but is expensive. For this reason, it is desired to develop a low-cost sensor that is capable of determining multiple colors and is not affected by the amount of light received.

[Conventional technology]

FIG. 3 is a block diagram of a conventional color sensor. In the figure, ■ indicates an object to be measured, 2 indicates a light emitting element driving circuit, 3 indicates a light emitting element, 4 indicates a light receiving element, 5 indicates a discrimination circuit, 6 indicates a comparison circuit, and 7 indicates an output circuit. In a conventional color sensor, a light emitting element drive circuit 2 drives a light emitting element 3 using a modulation signal of a specific frequency for discrimination, and the light emitted from the light emitting element 3 is reflected on an object to be measured 1. Light is received by the light receiving element 4 and photoelectrically converted. The discrimination circuit 5 detects an electric signal corresponding to the amount of reflected light through the filter of the discrimination frequency. The comparison circuit 6 determines the color by comparing the reflected light data stored in advance corresponding to the color with the detected electrical signal, and outputs the result from the output circuit 7.

In order to limit the irradiation light of the light emitting element 3 to the object to be measured 1 and the reflected light incident on the light receiving element 4 from the object to be measured 1 to a narrow range to avoid the influence of interfering light and improve measurement accuracy, a multi-mode mode (not shown) is used. In some cases, the light is irradiated or received through an optical fiber.

[Problem that the invention seeks to solve]

Conventional low-cost color sensors judge the color by comparing the amount of reflected light irradiated on the object to be measured 1 with the amount of reflected light corresponding to the color stored in a table in advance. Not only does the amount of foul light depend on the state of surface treatment or staining of the surface of the measurement object 1, but also only one color can be discriminated.

Another disadvantage is that high-cost image processing must be performed in order to solve these problems.

[Means for solving problems]

As shown in the principle diagram of FIG. 1, the color sensor of the present invention has the following features:
In a color sensor that receives reflected light from an object to be measured 1 irradiated with light in a predetermined band and identifies the color of the object based on the wavelength components of the reflected light, the reflected light is divided into a plurality of lights having different wavelength dispersion characteristics. The configuration includes a comparison circuit 12 that receives light in parallel to each of the light receiving elements (4, 10) via fibers (8, 9) and performs color discrimination based on the ratio of the amount of light received by each light receiving element. In the case of two systems, polycarbonate and acrylic resin are used as the cores of the optical fibers, respectively.

[Effect]

Since the light-receiving optical fiber of the present invention uses fibers with different wavelength dispersion characteristics, the amount of attenuation of the light incident on each fiber differs depending on the wavelength of the reflected light from the object to be measured 1, and each light-receiving element Since there is a difference in the output, the comparison circuit 12 detects the ratio, and compares it with pre-stored ratio data corresponding to the color to determine the color, and outputs the result from the output circuit 7.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

Note that, in order to make the explanation of the configuration and operation easier to understand, the same parts are given the same reference numerals throughout all the figures, and repeated explanation thereof will be omitted.

FIG. 2 is a block diagram of an embodiment of the present invention. In the figure, optical fiber 8 has a core made of polycarbonate, and optical fiber 9 has a core made of acrylic resin. Note that 8.9 may be a fluorescent-containing optical fiber of a different color tone.

The light receiving element 4 and IO are elements of the same standard, and the discrimination circuits 5 and 1) are also circuits of the same standard, and have the functions described in the conventional example. Reference numeral 12 denotes a comparison circuit, which has the function of detecting the ratio of the outputs of the discrimination circuits 5 and 1) and determining the color by comparing it with pre-stored ratio data corresponding to the color.
The result is output from the output circuit 7.

The light from the light emitting element 3 passes through the optical fiber 13 for light projection, and the measured object 1 is irradiated with light in a predetermined band, and the wavelength of the reflected light changes depending on the color of the measured object.

When this reflected light is received by the optical fiber 8 having a polycarbonate core and the optical fiber 9 having an acrylic resin core, for example, if the color of the object to be measured is blue, the reflected light also has a blue wavelength (300 to 800 nm). If so, polycarbonate has a large attenuation characteristic for wavelengths of 300 to 600 nm, but since the optical fiber 9 having an acrylic resin core is relatively small, a difference occurs between the outputs of the light receiving elements 4 and 10.

Further, when the reflected light is red (wavelength: 600 to 800 nm), the difference in attenuation between polycarbonate and acrylic resin is small, and the difference in output between light receiving elements 4 and 10 is also small.

Based on the principle described above, the comparison circuit 12 determines the discrimination circuits 5 and 1).
The color can be determined by detecting the ratio of the output of the color and comparing it with pre-stored ratio data corresponding to the color.

Note that it is also possible to realize a color sensor with even lower cost I· by omitting the light emitting element drive circuit 2 and the discrimination circuit 5.1), although the measurement accuracy is lowered.

〔Effect of the invention〕

As described above in detail, the color sensor of the present invention enables low-cost color discrimination.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the principle of the present invention, FIG. 2 is a block diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of a conventional color sensor. In FIG. 1, ■ indicates an object to be measured, 4 and 10 are light receiving elements, 8 and 9 are optical fibers having different wavelength dispersion characteristics, and 12 is a comparison circuit.

Claims (3)

[Claims] (1) A color sensor that receives reflected light from an object to be measured (1) that has been irradiated with light in a predetermined band, and identifies the color of the object to be measured based on the wavelength component of the reflected light; Multiple optical fibers with different dispersion characteristics (
A color sensor characterized in that a comparison circuit (12) is provided which receives light in parallel to the light receiving elements (4, 10) via the respective light receiving elements (8, 9) and performs color discrimination based on the ratio of the amount of light received by each light receiving element. (2) When the light receiving system is two systems, the optical fiber (8
, 9), wherein polycarbonate and acrylic resin are used as the cores, respectively.
Color sensor described in ). (3) The color sensor according to claim (1), wherein the optical fiber is made of a member containing a fluorescent material and having different light absorption and emission wavelength characteristics.