JPH0968462A - Device for measuring reflection coefficient - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an accurate measuring value even if dissociation and inclination are produced on a face to be measured. SOLUTION: A luminous flux from an illumination light source 22 illuminates a face S to be measured from the two directions of 45 degrees. Reflection light from the face S is photo-converted by a photo-diode array 28, transmitted to CPU 31 through an A/D converter 29, and necessary calculation is performed in a reflection coefficient calculation means 43 and a color calculation means 44 in CPU 31. The luminous flux emitted from a detection illumination light source 32 forms a point image on the face S by a light emission optical system 33, the point image is formed on a photo-diode array 36 by a dissociation error detection optical system 34, transmitted to a dissociation error detection means 45 through an A/D converter 38, and the presence of a dissociation error is detected. On the other hand, the luminous flux positively reflected on the face S enters an inclination error detection optical system 35, a point image is formed on an inclination error detection area sensor 37, an electrical signal is transmitted to an inclination error detection means 46, and the presence of an inclination error having corrected the previous dissociation error is detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflectance measuring device that measures the amount of reflected light from an object with high accuracy by photoelectric conversion means.

[0002]

2. Description of the Related Art Recently, reflectance measuring devices have been used not only to directly use the reflectance but also to measure the spectral reflectance and to measure the color value, glossiness, etc. of printing or object color. Therefore, the demand for high precision is becoming stronger.

Various methods for measuring reflectance and obtaining color values are specified in Japanese Industrial Standard JIS-Z8722 "Measuring method for object color". Among these, there are two measuring methods, measuring condition a and measuring condition b. These are the differences in whether the illumination system and the light receiving system are arranged 45 degrees apart or on the normal line (0 degree) with respect to the normal line of the object surface, and it can be considered that the geometrical arrangements are the same. , Generally 45-0 method, or 0
It is called the -45 method.

Here, a method generally called the 45-0 method will be described with reference to FIG. Figure 3 is 45-0
It is the schematic which shows the structure of a system. The luminous fluxes emitted from the light sources 1a and 1b become parallel luminous fluxes La and Lb in the illumination optical systems 2a and 2b, which are emitted from the measurement head unit 3 and illuminate the surface S to be measured from two positions in the oblique 45 degree direction. At this time, there are a method of abutting the surface S to be measured against the measurement head unit 3 and a method of maintaining a constant interval. In FIG. 3, the measurement head unit 3 and the surface S to be measured maintain a constant distance d.

The light flux reflected by the surface S to be measured passes through the upper condensing optical system 4 and reaches the photodiode array 5 for detecting the light intensity for each wavelength, and the light flux detected by each element is photoelectrically converted. , It can be changed to the strength of the electric signal. After that, the signal digitized by the A / D converter 6 is stored in the memories 7a and 7b in the CPU 7 together with the wavelength data.

At this time, a standard reflector having a known reflectance is selected as the object to be measured, and the reference set value of reflection is stored in the memory 7a.
The reflectance data of the surface S to be measured is stored in the memory 7b, the reflectance calculation means 8 in the CPU 7 calculates the reflectance for each wavelength, and the color value calculation means 9 uses the JIS prescribed calculation method. You can get the value of the color space.

[0007]

In this reflectance measuring device, the reproducibility of measurement is good when the irradiation optical systems 2a and 2b and the condensing optical system 4 reaching the photodiode array 5 are fixed. However, as described above, the conventional apparatus has two types of methods, that is, a method of separating the surface S to be measured and the measurement head unit 3 from each other and a method of closely contacting each other, and either method is selected. In the non-contact type as shown in FIG. 3, the distance d and the inclination between the measurement head unit 3 and the surface S to be measured cannot always be kept the same as those of the standard reflection surface.
If the surface S to be measured or the person to be measured is changed, it is likely to change and cause a measurement error.

In order to prevent this error, the conventional method uses a means for making the illumination light beam to the surface S to be measured smaller than the effective diameter of the condensing optical system 4, but it is not always effective.
On the other hand, in the device for measuring by closely contacting the measurement head section 3 and the surface S to be measured, there is a risk that the measurement head section 3 may cause an inclination, the measurement head section 3 may scratch the sample surface, or the paper may be damaged. An object such as a thin plate or a thin plate may have an uneven measurement surface, which similarly causes a measurement error.

As for the object to be measured having a high diffusivity, the surface S to be measured irradiated from the illumination system 11 shown in FIG. 4 has a substantially uniform reflection characteristic r in any direction. Even if the surface S to be measured has an inclination ε with respect to the light receiving optical system 12 and the light receiving unit 13, there is little change in the photometric amount. However, for example, when the measured surface S deviates from the reference position by d as shown in FIG. 6, the apparent solid angle θ2 to the light receiving optical system 12 changes as compared with the solid angle θ1 in FIG. Part 1
The amount of light reaching 3 changes.

On the other hand, the surface S to be measured having a low diffusivity and gloss
As for the reflected light R from the surface S to be measured shown in FIG. 7, the directivity is strong. Therefore, when the surface S to be measured has an inclination ε with respect to the light receiving optical system 12 as shown in FIG. The light flux focused on the optical system 12 changes, resulting in an error in the photometric amount.
However, as shown in FIG. 9, even if the measurement surface S deviates from the reference position, the direction of the specularly reflected light beam does not change, and the diffused light changes only slightly. Without it, measurement error will not occur.

An object of the present invention is to solve the above-mentioned problems,
An object of the present invention is to provide a reflectance measuring device that can obtain an accurate measurement value even if a deviation or a tilt occurs in the object to be measured.

[0012]

In the reflectance measuring apparatus according to the present invention for achieving the above object, there is provided a measuring apparatus for measuring the amount of light reflected on a sample surface to be measured to obtain the reflectance. It is characterized in that at least one of a deviation error detecting means and a tilt error detecting means from a measurement reference position is provided with respect to the attachment position of the sample surface to be measured.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a block diagram showing the configuration of a color measuring device using a reflectance measuring device,
45-degree illumination specified by JIS, vertical light reception (45-0)
It is a device based on the law. A means for notifying that the measurement sample mounting position is inaccurate when the deviation and tilt amount detection mechanism from the measurement sample mounting reference position is activated, and a means for correcting it to the correct position Is.

A measuring illumination light source 22 is provided inside the measuring device body 21, and a condenser lens 23 and an incident end of a fiber 24 are arranged in front of the illumination light source 22. The fiber 24 is divided into two fibers 24a and 24b on the way,
Illumination optical systems 25a and 25b are arranged in front of these emission ends, and the emitted light from the fibers 24a and 24b is emitted as parallel light from a diagonal two directions to a measurement head portion 26 that opens to the lower part of the measuring device body 21. It is directed to the surface S to be measured.

A measuring condensing optical system 27 and a photodiode array 28 are arranged above the reflection direction along the normal line of the surface S to be measured, and the output of the photodiode array 28 is an A / D converter including an amplifier. It is connected to the CPU 31 via the device 29.

A measuring illumination light source 32 formed of a semiconductor laser light source is arranged inside the measuring instrument body 21, and a projecting optical system 33 is provided between the detecting illumination light source 32 and the measuring head portion 26. A photodiode array 36 and an area sensor 37 are provided in the reflection direction of the surface S to be measured of the projected light flux via detection optical systems 34 and 35, respectively. Photodiode array 36, area sensor 3
The outputs of 7 are A / D converters 38 and 3 each including an amplifier.
It is connected to the CPU 31 via 9. Here, the detection optical system 34 and the photodiode array 36 are arranged in the vicinity of the normal line of the reflection surface and are used for detecting the deviation error, and the detection optical system 35 and the area sensor 37 are almost the same as the illumination light source 32 across the normal line. They are arranged symmetrically and are used for tilt detection.

The housing 41 in the measuring device main body 21 includes the light-transmitting and receiving optical system for photometry within the range shown in the drawing, and these are housed as one unit inside. However, for the sake of convenience in the drawing, the actual arrangement is different from the paper surface. It is in a position orthogonal to each other. Also, the illumination optical system 25a
Although 25 and 25b are illustrated as being included in the housing 41, they are not actually included.

The CPU 31 includes memories 31a, 31b and 31.
In addition, a system control means 42, a reflectance calculation means 43, a chromaticity value calculation means 44, a deviation error detection means 45, and a tilt error detection means 46 are provided. Also,
The CPU 31 is connected with a deviation / tilt control means 47, a position quality display means 48, and a display output means 49, and the output of the deviation / tilt control means 47 is a deviation / tilt adjustment for driving the housing 41 with respect to the measuring device main body 21. It is connected to the drive unit 50.

At the time of measurement, the luminous flux from the illumination light source 22 is condensed by the condenser lens 23, passes through the fiber 24, and
It is divided into directions 24a and 24b. Fibers 24a, 2
The luminous flux emitted from the emission end of 4b is the illumination optical system 25a,
25b illuminates the surface S to be measured from two directions of 45 degrees. The surface S to be measured is the measuring head portion 26 of the measuring device main body 21.
Although they are arranged apart from each other by d, they are arranged below the measuring device main body 21 so as not to be affected by external light.
The surface S to be measured may be held together with the device on a flat surface such as a work desk, and it is not necessary to use a special device.

The condensing optical system 27 condenses the reflected light from the surface S to be measured, determines the measurement range so that the focal point substantially coincides with the surface S to be measured, and detects the light intensity for each measurement wavelength. A uniform spread is made in the photodiode array 28. The light flux photoelectrically converted by the photodiode array 28 becomes an electric signal having strength information, becomes a digital signal through the A / D converter 29, reaches the CPU 31, and is stored in the memory.
After that, necessary calculation is performed in the reflectance calculation means 43 and the color calculation means 44 in the CPU 31, and the display output means 4
The result is displayed at 9.

The principle of the error detecting means is the triangulation method, and the deviation of the focal position is detected as the deviation on the photodiode array 36. The light flux emitted from the detection illumination light source 32 forms an extremely small point image on the surface S to be measured by the projection optical system 33. This point image is formed on the photodiode array 36 by the deviation error detection optical system 34 arranged near the normal to the surface S to be measured. The point image formed on the photodiode array 36 moves to a substantially linear position according to the amount of deviation of the surface S to be measured. Further, the electric signal having the photoelectrically converted point image position information is sent to the deviation error detection means 45 in the CPU 31 through the A / D converter 38, and the presence or absence of the deviation error is detected.

On the other hand, the tilt error detection optical system 35, which is installed substantially symmetrically with respect to the light source 32 and the projection optical system 33 with the normal line of the surface S to be measured sandwiched, is regularly reflected by the surface S to be measured. Light flux enters and forms a point image on the tilt error detection area sensor 37. The point image formed on the area sensor 37 changes to a substantially linear position according to an error including a deviation and a tilt.
Furthermore, the electric signal containing the photoelectrically converted point image position information is
It is sent to the tilt error detecting means 46 in the CPU 31 via the A / D converter 39, and the presence or absence of the tilt error in which the deviation error is corrected is detected.

When the measured surface S is a diffusion surface, the deviation error detecting means 45 can detect the point image as the deviation amount, but cannot detect the tilt. If the surface S to be measured has sufficient gloss, the point image light beam is specularly reflected and does not enter the light receiving portion, and cannot be similarly detected. In the tilt error detection means 46, the movement of the point image due to the deviation and the tilt error similarly fluctuates, and the two cannot be distinguished. Therefore, in this embodiment, the deviation error detecting means 4
The error is accurately detected from both the No. 5 and the inclination error detecting means 46.

The deviation / tilt adjustment drive unit 50 provided at the connecting portion between the housing 41 and the measuring device main body 21 is operated by a signal from the deviation / tilt control means 47. The deviation / tilt control means 47 is OK from the CPU 31,
The drive adjustment unit 50 is driven while communicating the NG signal to set the housing 41 to the correct position. The presence / absence of deviation or tilt error and the display during adjustment are displayed on the position pass / fail display means 48 by the CPU 3.
Display according to instructions from 1.

Next, the procedure for measuring the spectral reflectance and obtaining the color value will be described with reference to the flow chart of FIG. After the power is turned on, in step 1, deviation error and inclination error detection criteria are set. The position setting reflection plate placed at the same position as the surface S to be measured is used to detect the correct mounting position, that is, the deviation reference and the inclination by the detection mechanism by the respective photodiode array 36 and area sensor 37. The position is stored in the memory for error detecting means in the CPU 31.

Here, it is desirable that the setting reflection plate to be used has an intermediate gloss and is flat. Since the standard reflective white plate described in step 3 has good diffusivity, the inclination standard cannot be set. In other words, the inclination error does not affect the measurement accuracy with a substance having good diffusibility, but can be used when the surface S to be measured has good diffusibility and only the deviation error needs to be set.

In step 2, dark measurement is performed on the measuring head unit 2.
6, the dark current and the leakage current are detected by the photodiode array 36 for each wavelength, and the deviation error detecting means 4 is detected.
Store in memory of 5. Note that this step 2 can be performed after step 4.

In step 3, the deviation error of the standard reflection white plate having high reflectance and diffusivity placed almost in the same manner as the position setting reflection plate for detecting the position of the standard reflection white plate is detected by the deviation error detecting photodiode. Array 36 detects C
Send to the deviation error detection means 45 in the PU 31, step 1
The deviation error from the position of is detected. The inclination error is not detected for the reason described above.

In step 4, when the deviation error detecting means 45 detects the deviation error in the position control of the standard reflecting white plate, the system control means 42 of the CPU 31 sends a detection signal to the deviation / tilt control means 47 to detect the deviation / tilt. The adjustment drive unit 50 is moved to adjust the posture of the housing 41. On the other hand, the position pass / fail display means 48 displays the pass / fail result as a lamp,
When it is set to the correct position, the good lamp is lit and displayed, and the process moves to the next step.

In step 5, since the reflection amount of the standard reflection white plate serving as a reference for the amount of reflected light is known, the amount of light is used as a reference, the photodiode array 36 measures the wavelength, and the deviation error detecting means 45 in the CPU 31. Stored in memory.

In step 6, the surface S to be measured is attached and the attachment position is detected. The surface S to be measured is placed at the same position as the standard reflection white plate measured in step 3, and the difference between the position detected by the deviation error detecting means 45 and the tilt error detecting means 46 and the reference position set in step 1 is detected as a deviation error. The means 45 and the tilt error detection means 46 compare.

In step 7, if an error is detected by the error detection means 45, 46 in the position adjustment of the surface S to be measured, it is transmitted to the deviation / tilt control means 47, and the deviation / tilt adjustment driving section 5 is sent.
Adjust by 0. On the other hand, the position pass / fail display means 48 displays the pass / fail result as a lamp. When it is set to the correct position, the good lamp is lit and displayed, and the process proceeds to the next step 8. In step 8, the amount of light reflected by the surface S to be measured is measured, and the amount of light detected by the photodiode array 28 for each wavelength is stored in the memory of the reflectance calculating means 43 in the CPU 31.

In step 9, the reflectance is calculated and displayed,
Data for each wavelength measured in step 5 and step 8,
The reflectance calculation means 43 calculates the reflectance for each wavelength based on the dark current measured in step 2.

In step 10, the chromaticity value is calculated and C
The calculation is performed by the method determined by the chromaticity value calculation means 44 in the PU 31, the color value is output by the display output means 49, and the processing is ended. Then, when another sample is measured, it starts from step 6.

In the above measurement, depending on the glossiness of the surface S to be measured, either the deviation error or the inclination error may be detected, and the other may not be detected. However, as explained in the section of the prior art, the undetected error does not affect the measurement accuracy, and in this embodiment, the lamp of the position pass / fail display means 48 is set to be good when it cannot be detected. .

In the present embodiment, an example in which the color measurement is limited is given, but the density system measured by almost the same optical system,
It can be used for a reflectance measuring device such as a gloss meter and image clarity measurement in which a setting error of an object to be measured also affects the light amount. In addition, although the embodiment using the detection mechanism for both the deviation error from the measurement sample attachment reference position and the inclination error has been described, there is no problem even if only one of them is detected due to the cost of the device.

[0037]

As described above, according to the reflectance measuring apparatus of the present invention, in the reflectance measurement, it is possible to know whether or not the mounting state of the surface to be measured is correct before measuring the amount of light, thereby improving the measurement accuracy. So I noticed the mistake after analyzing the measured values,
It is not necessary to perform remeasurement. In addition, since it is possible to perform the measurement without worrying about the setting error of the position, it is possible to perform the measurement efficiently, which is advantageous in terms of cost and time.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an embodiment.

FIG. 2 is a flowchart of a measuring method.

FIG. 3 is a schematic view of a colorimeter using a conventional reflectance measuring device.

FIG. 4 is an explanatory diagram of an error of a diffused sample in a conventional reflectance measurement.

FIG. 5 is an explanatory diagram of an error of a diffused sample in the conventional reflectance measurement.

FIG. 6 is an explanatory diagram of an error of a diffused sample in a conventional reflectance measurement.

FIG. 7 is an explanatory diagram of an error of a gloss sample in the conventional reflectance measurement.

FIG. 8 is an explanatory diagram of an error of a gloss sample in the conventional reflectance measurement.

FIG. 9 is an explanatory diagram of an error of a gloss sample in the conventional reflectance measurement.

[Explanation of symbols]

 21 Measuring instrument main body 22 Illumination light source for photometry 27 Condensing optical system for colorimetry 28, 36 Photodiode array 31 CPU 32 Illumination light source for detection 37 Area sensor 41 Housing 43 Reflectance calculation means 44 Chromaticity value calculation means 45 Deviation error Detecting means 46 Tilt error detecting means 47 Deviation / tilt control means 50 Deviation / tilt adjustment drive section S Surface to be measured

Claims (3)

[Claims] 1. A measuring device for measuring the amount of light reflected on a sample surface to be measured to obtain a reflectance, wherein the mounting position of the sample surface to be measured is deviation error detection means from a measurement reference position and inclination error detection. A reflectance measuring device comprising at least one of: 2. The deviation error detecting means and the inclination error detecting means share a light source irradiated from one location, and the deviation error detecting means is a deviation sensor which is arranged near a normal to a surface to be measured. 2. The reflectance measuring device according to claim 1, wherein the error detecting means photoelectrically detects the area by an area sensor arranged symmetrically to the light source with the normal line in between. 3. When the deviation position or inclination of the sample surface to be measured is inaccurate, the function of measuring the amount of reflected light is stopped,
2. A device having at least one of a device for notifying that the function has stopped and a device for correcting the function to a correct position.
2. The reflectance measuring device according to 1.