KR890001688B1 - Color-measuring spectrophotometer system for source - Google Patents

Abstract

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Description

Spectrophotometer System for Color Measurement of Samples

1 is an overall system layout of the present invention.

The present invention relates to the development of a spectrophotometer for measuring the spectroscopic diffuse reflectance and color coordinates of a sample used in industries that require color measurement and management, such as dyeing companies.

The conventional spectrophotometer used for this purpose can be classified into a structure such as a xenon bulb or a tungsten halogen bulb as a light source and a photomultiplier tube (PHT) or a silicon photodiode as a photodetector. Diffraction gratings or interference filters are used as the illumination conditions, and multi-color light or monochromatic light is used as the illumination conditions. The geometrical shape of the light source constitutes the entire system as double light or single light.

In the present invention, the system is equipped with the conditions of tungsten halogen bulb, silicon photodiode, interference filter, monochromatic light, monochromatic light, and at the same time, it is possible to reduce manufacturing cost and at the same time, to correct the measurement accuracy which is a disadvantage of these conditions, Reduce the stray light of the interference filter by installing the optical absorption filter, and reduce the measurement error of the fluorescent sample by installing the blue optical absorption filter in front of the silicon photodiode. This reflects the precision that allows the computer to correct the reflectance measurement errors raised by the short beam optical system.

Hereinafter, the present invention will be described with reference to the accompanying drawings and examples.

First, as a whole system, the light source of the tungsten halogen bulb 2 by the DC power supply 1 is provided with 16 interference filters 5 installed in the focusing lens 3 → stepping motor 4 → an achromatic lens 6 →. The blue optical absorption filter (7) → the optical splitter (8) is closed to the sample (10) through the integrating sphere (9), and the reflected light is passed through the blue optical absorption filter (11) to the silicon photodiode (12). The A / D converter 13 is connected to the A / D converter 13 through the silicon photodiode 14 in the simultaneous optical splitter 8 and the A / D converter 13 is a stepping motor. It is a color measurement spectrophotometer system of a sample connected to the microcomputer 16 to which the controller 15 is connected.

When the principle of the spectrophotometer is outlined to explain the effect of the present invention, the spectrophotometer is divided into a light source unit, a spectrometer, a measurement unit, and a microcomputer used to control them and process the measured data. The characteristics of the light source, the spectrometer, and the measurement unit should all be considered. First, the light source unit is composed of a tungsten halogen bulb (2) and a direct current power source (1). Since the power must be manufactured separately, the manufacturing cost of the whole device becomes high.

However, if AC power is used, the measurement time should be long because an electronic filter (CLECTRONIC FILTER) with a large time constant must be configured. Therefore, the measuring equipment that does not significantly affect the measurement time is long, but may use an AC power source, but when measuring more than 16 points per sample, such as a spectrophotometer, the DC power source should be used as in the present invention.

The spectroscopic section is composed of a focusing lens 3 for focusing light emitted from a light source, 16 interference filters 5 and an optical absorption filter 7.

This is inexpensive compared to the method using a diffraction grating and the machine driving device is simplified. The interference filter 5 has a maximum transmittance value of 20 nm in the interval of 400 nm to 700 mm wavelength, and each filter has a FWHW of 10 nm. It has a band width of (FULL WIDTH AT HALF MAXIMUM) and a transmittance of 10 ^-5 at other wavelengths.

In the spectrophotometer, only the 40nm-700nm wavelength region is measured. In addition, light in the wavelength region is removed by using heat-absorbing glass having transmission characteristics.

The sixteen interference filters 5 are arranged on a circumference of 20 cm in diameter on a disk 5a having a diameter of 24 cm, and the step 5 is rotated using a stepping motor 4 to rotate the disk 5a in a wavelength region of 400-700 nm. To get monochromatic light.

Next, the optical system of the spectroscopic section will be described. The light from the tungsten halogen bulb 2 serving as the light source is focused by the connection lens 3 and transmitted through the interference filter 5. The light transmitted through the interference filter 5 is absorbed by the optical absorption filter 7 with an infrared ray having a wavelength longer than 800 nm, and the interference filter (A) is applied to the surface of the sample 10 of the integrating sphere 9 by the acromet lens 6. 5) bear the image of the lens located in front of.

The light reflected by the optical splitter 8 located in front of the integrating sphere 9 is incident on the silicon photodiode 14 to compensate for the change in the measured value caused by the output change. In this device, silicon photodiodes 12 and 14, which are optical sensors, act as O / E converters that convert an optical signal into an electrical signal. Light absorbed from the PN junction of the silicon photodiode generates electrons and holes. As the electrons and holes move to the electrode, a current signal is transmitted, and the current signal is an analog signal proportional to the incident optical signal, and the analog electric signal is converted into a digital electric signal by the A / D converter 13.

Next, illuminate the specimen surface in the vertical direction to measure the color of the surface as illumination and observation conditions of the measurement unit, and receive the light reflected from all directions except the specular reflection light through the integrating sphere. The luminous flux should not be more than 10 degrees and the light beam should not contain more than 5 degrees of the central axis, and the integral sphere shall not exceed 10% of the inner surface of the integral sphere, regardless of size.

In the vertical / diffusion method of the present invention, the light is vertically incident on the sample so that the specularly reflected light passes out of the integrating sphere through the opening of the integrating sphere. Widely used photodetectors in the visible range are silicon photodiodes and P.M tubes.

The photodetector of the present invention is a silicon photodiode, which is low in spectroscopy and sensitivity compared to PM tubes, but has the advantages of low cost and high stability. In particular, in the optical system that compensates for the change in the light output by using a beam splitter, two photodetectors having good stability are required, so that silicon photodiodes are cheaper than PM tubes. However, since the silicon photodiode has low spectral sensitivity, the optical system must be configured to inject monochromatic light of 10 ^-8 watt / cm ² or more into the two silicon photodiodes 12 and 14, thus configuring the optical system as shown in FIG. By connecting the bulb to a 20V DC power source, more than 10 ^-8 watt / cm ² of monochromatic light was incident on the silicon photodiode in the 400-700nm wavelength region.

디지트(DIGIT)의 디지탈신호(DIGITAL SIGNAL)로 변환되어 컴퓨터에 입력됨으로 단색화 장치의 파장은 컴퓨터에 의해 제어시킨 것이다. 이와같이 된 본 발명은 그 구조가 간단하고 가격이 저렴하며 확산반사율 측정오차는 2%이하로서 산업현장에서 훌륭하게 활용될 수 있는 수준인 것이다.The light from the monochromator is incident on the silicon photodiode, causing the photocurrent to flow, which is then converted to voltage in a current to voltage converter (CURRENT TO VOLTAGE CONVERTER).

The wavelength of the monochromator is controlled by a computer because it is converted into a digital signal of a digital signal and input to a computer. The present invention thus obtained has a simple structure, low cost, and a diffuse reflectance measurement error of 2% or less, which is a level that can be effectively utilized in industrial fields.

Claims (1)

After the light from the tungsten halogen bulb 2 by the DC power supply 1 passes through the connection lens 3, the 16 interference filters 5 installed on the disc 5a rotated by the stepping motor 4 are removed. The light passing through the matte lens (6) through the light arc, and then the blue optical absorption filter (7) installed behind the light splitter (8) through the integrating sphere (9) to the sample (10) and the reflecting tube The blue optical absorption filter 11 is connected to the A / D converter 13 via the silicon photodiode 12 via the diesel light, and the light reflected by the optical splitter 8 is also transferred through the silicon photodiode 14. Spectrophotometer system for measuring the color of the sample characterized in that the system connected to the / D converter (13), the A / D converter (13) is connected to the microcomputer (16) to which the stepping motor controller (15) is connected.

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