JPH07128148A - Color measuring apparatus - Google Patents

Abstract

PURPOSE:To process a signal at a good S/N ratio and to correctly measure a color by a method wherein, when a fluorescence-cut filter is inserted and light of an object to be measured does not contain fluorescence, a dynamic range is narrowed. CONSTITUTION:The dynamic range (DR) of an A/D converter 18 is set at 200%, and an object 12 to be measured is irradiated with a light source 11. The light (transmitted light) is spectrum-decomposed by a slit 15 and a spectral element 16, light at a prescribed wavelength is received by a detector 17, and it is converted (quantized) into digital data by the A/D converter 18. An operation and control part 20 to which the digital data has been inputted processes the data, and it decides a color. At this time, when the light contains fluorescence, the DR is set as it is, a wavelength region in which its intensity has been increased by the fluorescence is quantized precisely, and the color is decided correctly. When the light excluding the fluorescence is to be measured, a fluorescence-cut filter 13 is inserted between the object 12 to be measured and the slit 15, the control part 20 reduces the DR to 100% at a point of time when a filter sensor 14 detects it. Thereby, an S/N ratio is enhanced in an A/D conversion, and the color can be measured precisely.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color measuring device.

[0002]

2. Description of the Related Art A color measuring apparatus receives light transmitted through a predetermined light source (including natural light) or light reflected on the surface of an object to be measured, obtains a spectrum thereof, and obtains intensity data of each wavelength. After the extraction, the color is determined by performing a predetermined calculation. Since the calculation for determining the color is usually performed by a microcomputer, the received light signal is temporarily set to A for each wavelength.
It is converted into digital data by the / D converter.

Some of the objects to be measured emit fluorescence, but in this case, there is a possibility that light having an intensity exceeding the incident intensity may be detected by the light receiver depending on the wavelength. Therefore, conventionally
The dynamic range of the A / D converter is 20 times the intensity of the light source.
It was set based on 0%.

[0004]

When the object to be measured does not contain a fluorescent substance, the intensity of light detected by the light receiver is naturally less than the intensity of incident light (that is, 100% or less). However, in the conventional device, since the dynamic range of the A / D converter is fixed at 200% as described above, when measuring a color that does not contain a fluorescent substance or a color in which fluorescence is removed, Input signal S / at the time of D conversion
There is a drawback that the N ratio deteriorates.

The present invention has been made in order to solve such a problem, and its purpose is to always process a signal with a good S / N ratio according to the object of use and the purpose, and An object of the present invention is to provide a color measuring device capable of measuring color.

[0006]

SUMMARY OF THE INVENTION The present invention, which has been made to solve the above problems, irradiates an object to be measured with light having a predetermined intensity, and measures the object to be measured based on the spectrum of transmitted light or reflected light. A) a photodetector that detects transmitted light or reflected light of an object to be measured and outputs an analog signal corresponding to the intensity, b) an object to be measured and a photodetector. Filter detection means for detecting that a fluorescence cut filter is inserted in the optical path between the two, and c) A / D for converting the analog signal into digital data.
A converter, which is an A / D converter capable of changing the dynamic range at the time of conversion into at least two kinds of wide and narrow, and d) when the filter detecting means detects that a fluorescence cut filter is inserted in the optical path. , And a dynamic range switching means for switching the dynamic range of the A / D converter to a narrower one.

[0007]

When the transmitted light or the reflected light from the object to be measured enters the photodetector, the photodetector outputs an analog signal corresponding to the intensity of each wavelength. This analog signal is converted into digital data by an A / D converter, and the color is determined based on the intensity data of each wavelength.

When the object to be measured contains a fluorescent substance and the color whose fluorescence is removed is to be measured, a fluorescence cut filter is inserted in front of the photodetector. When the filter detecting means detects this, the dynamic range switching means switches the dynamic range of the A / D converter to a narrower one. Since the intensity of the light from the object to be measured is reduced by the fluorescence cut filter, the conversion accuracy at the time of A / D conversion is improved, and more accurate color measurement becomes possible.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A measuring range variable colorimeter which is an embodiment of the present invention will be described with reference to FIGS. The DUT 12 is placed at a predetermined position, and the light source 11 emits white light having a predetermined intensity. The DUT 12 reflects light having a wavelength corresponding to the color and absorbs light having other wavelengths. In this way, the light (reflected light or transmitted light) having a spectral characteristic according to the color of the DUT 12 is decomposed into a spectrum by the slit 15 and the spectroscopic element 16, and a photodetector (photodiode array) for each predetermined wavelength range. Etc.) 17.

The intensity signal detected for each wavelength range by the photodetector 17 is converted (quantized) into digital data having a predetermined number of bits by the A / D converter 18.
The A / D converter 18 can change the dynamic range from the outside, and performs the A / D conversion according to the dynamic range instructed from the outside. For example, when the dynamic range is specified to be 1V, the analog signal of 1V sent from the photodetector 17 is the maximum digital data (for example, if it is 12-bit quantization, 1V).
0 ¹² = 4096), and when the dynamic range is instructed to be 0.5V, an analog signal of 0.5V is converted into maximum digital data 4096.

Digital data corresponding to the intensity of each wavelength range is sent to the arithmetic / control section 20, and the arithmetic / control section 20 stores a program stored in an internal ROM (not shown) based on the data. According to the above, predetermined data processing for color determination is performed (for example, JIS Z81
05). The calculation / control unit 20 includes an input unit 21 such as a keyboard and a display unit 2 such as an LCD (liquid crystal display).
2 is connected, and the result of data processing is output to the display unit 22.

The colorimeter of this embodiment is provided with a place where the fluorescence cut filter 13 is inserted between the object to be measured 12 and the slit 15 of the spectroscope, and the color of the object to be measured 12 excluding the fluorescence is measured. When it is desired to measure, the operator inserts the fluorescence cut filter 13 according to the object to be measured. Also,
A filter sensor 14 for detecting that the fluorescence cut filter 13 is inserted in the optical path is provided here, and a detection signal is sent to the calculation / control unit 20.

The procedure of color measurement by this colorimeter will be described with reference to FIG. First, the dynamic range (DR) of the A / D converter 18 is set to 200% (step S1).
Here, the dynamic range of 200% means the light source 1
This means that the white light of No. 1 is split by the spectroscopic element 16 as it is, and the light having the intensity twice (100%) when received by the light receiving element 17 is quantized to the maximum value. Then, it is determined whether or not the light obtained by passing through the DUT 12 or being reflected by the surface thereof contains fluorescence (step S2). This can be determined by, for example, whether or not the intensity of each of the separated wavelengths exceeds the intensity of the light source light. When it is determined that the light from the DUT 12 does not include fluorescence, the calculation / control unit 20 sets A /
The dynamic range of the D converter 18 is set to 100% (step S7), the light from the object to be measured 12 is spectroscopically measured (step S8), and predetermined data processing is performed (step S9). Determine the 12 colors.
In this case, since the dynamic range is reduced according to the amount of light transmitted or reflected from the object to be measured 12, the S / N ratio at the time of A / D conversion is improved, and more accurate color determination is possible.

When it is determined in step S2 that the light from the object to be measured 12 contains fluorescence, the calculation / control unit 20 causes the display unit 22 to "select a measurement mode."
Is displayed. This is because the operator is asked whether to measure the color including fluorescence, or to measure the color excluding fluorescence, and in which mode the measurement is performed, and to have the input section 21 make an input. Is a display (prompt). When the operator inputs from the input unit 21 that the measurement including fluorescence is performed, the calculation / control unit 20
Performs color measurement as it is (that is, DR = 200% remains) without changing the dynamic range of the A / D converter 18 (steps S8 and S9). As a result, the wavelength range in which the intensity is increased by fluorescence can be quantized accurately, and correct color measurement can be performed.

On the other hand, if the operator inputs that color measurement should be performed without fluorescence, the calculation / control section 20 then displays a prompt message "Please insert a fluorescence cut filter in the optical path." 22 is displayed. And
Whether or not the fluorescence cut filter is actually inserted in the filter insertion portion is judged by the signal from the filter sensor 14 (step S6), and if not inserted, the prompt message is repeatedly displayed (step S5). When it is detected that the fluorescence cut filter is inserted,
A signal for making the dynamic range 100% is sent to the A / D converter 18 (step S7), and color measurement is performed (steps S8, S9).

Although the filter sensor 14 for detecting the insertion of the fluorescence cut filter 13 is provided in the above embodiment,
Instead of providing such a sensor, the operator may be allowed to perform a key input to that effect through the input unit 21. In this case, the calculation / control unit 20 which determines the key input to that effect serves as the filter detection means of the present invention. When it is determined that the light from the DUT 12 contains fluorescence,
Color measurement may be performed in a predetermined procedure without requiring the operator to input the measurement mode as in the above embodiment (for example, when it is determined that fluorescence is included, it is automatically It is specified that the color measurement including fluorescence will be performed). In this case, it is desirable to provide a filter drive mechanism that inserts and removes a filter according to a command from the arithmetic / control unit 20.

[0017]

In the color measuring apparatus according to the present invention, the fluorescence cut filter is inserted, and when it is clear that the light from the object to be measured does not contain fluorescence, the A / D converter A / by reducing the dynamic range
The S / N ratio at the time of D conversion is improved. This makes it possible to determine a more accurate color.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a colorimeter that is an embodiment of the present invention.

FIG. 2 is a flowchart showing an example of a color operation of the embodiment.

[Explanation of symbols]

 11 ... Light source 12 ... Object to be measured 13 ... Fluorescence cut filter 14 ... Filter sensor 16 ... Spectral element 17 ... Light receiving element 18 ... A / D converter 20 ... Calculation / control section 21 ... Input section 22 ... Display section

Claims (1)

[Claims] 1. A color measuring device for irradiating an object to be measured with light of a predetermined intensity and measuring the color of the object to be measured based on the spectrum of transmitted light or reflected light thereof, wherein: a) transmitted light of the object to be measured. Alternatively, a photodetector that detects reflected light and outputs an analog signal corresponding to its intensity, and b) Filter detection that detects that a fluorescence cut filter is inserted in the optical path between the DUT and the photodetector. Means and c) A / D for converting the analog signal into digital data
A converter, which is an A / D converter capable of changing the dynamic range at the time of conversion into at least two kinds of wide and narrow, and d) when the filter detecting means detects that a fluorescence cut filter is inserted in the optical path. , A dynamic range switching means for switching the dynamic range of the A / D converter to a narrower one, and a color measuring device.