JP3026972B1 - Measurement method of glossiness of object surface - Google Patents

Abstract

[Problem] (Diffuse reflection light) / (Specular reflection light and diffuse reflection light)
Is extracted as two current values corresponding to the light amounts of the respective reflected light components, and is compared to determine the glossiness of the object surface. A position detection sensor irradiates an object with light rays included in an infrared to visible region and reflects the light, and separates the light into reflected light passing through a phase difference film and a polarizing plate and reflected light passing through a polarizing plate. And performs signal processing on an output current corresponding to the amounts of the two reflected lights.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for measuring the glossiness of an object surface by performing signal processing on an output current corresponding to the amount of reflected light.

[0002]

2. Description of the Related Art Conventionally, when measuring the glossiness of the surface of an object, the surface of the object is irradiated with infrared light, visible light, or the like, and the reflected light is received by an element such as a color sensor or a linear image sensor and output. The current was detected by signal processing.

[0003]

However, when the gloss sensor having the above structure is used, the color sensor, the linear image sensor, and the like are expensive and the signal processing after receiving light by the sensor element is complicated. Therefore, there is a problem that the price of the gloss sensor itself becomes expensive. On the other hand, when an inexpensive two-terminal photodiode is used as the sensor element, the amount of reflected light varies depending on the color density of the sample surface, and the reflected light from the sample to be measured is mixed with specularly reflected light and irregularly reflected light. For this reason, there is a problem that accurate measurement of glossiness is very difficult.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems, and irradiates an object with light rays included in the infrared to visible regions to reflect the light, and reflects reflected light passing through a phase difference film and a polarizing plate. And a reflected light passing through a polarizing plate, which is detected by a position detection sensor, and an output current corresponding to the light amounts of the two reflected lights is signal-processed. is there. Further, the above retardation film is 1 /
This is a method for measuring the glossiness of the surface of an object, which is a two-wavelength plate or a transparent film exhibiting a birefringence effect. The two reflected lights are specularly reflected light and irregularly reflected light,
This is a method for measuring the glossiness of an object surface, which is irregularly reflected light.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Regardless of the color density on the surface of an object, the glossiness of the surface of the object is measured as an output current corresponding to the amount of reflected light and signal processing. At this time, an inexpensive gloss sensor is provided with a simple configuration such as a position detection sensor (hereinafter, referred to as a PSD), a retardation film, and a polarizing plate without using expensive semiconductors such as a color sensor and a linear image sensor. be able to.

[0006]

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

[Embodiment 1] FIG. 1 shows the structure of a gloss sensor using the method for measuring the gloss of an object surface according to the present invention.
In FIG. 1, the light source 1 and the PSD 6 are arranged so that the incident angle and the reflection angle of light with respect to the sample 3 to be measured are equal. The light from the light source 1 is applied to the sample 3 to be measured in the form of spot light using the condenser lens 2. It is not always necessary to concentrate the light spots at one point. As the light source 1, a light source having a large single wavelength component such as a halogen lamp and a semiconductor laser can be used in addition to the LED.

FIG. 2 shows details on the light receiving side of FIG. With respect to the reflected light b before passing through the half-wave plate 4 and the polarizing plate 8 shown in FIG. 2, the vertical vibration component e with respect to the sample 3 to be measured is p-wave, and the horizontal vibration component d is s-wave. In this case, the specularly reflected light is a reflected light composed of only the s-wave according to the law of reflection, and becomes more dominant as the glossiness of the sample surface increases. Diffusely reflected light is diffuse reflected light excluding specularly reflected light and has various vibration directions including s-waves and p-waves, and becomes more dominant as the glossiness of the sample surface is lower.

The transmission direction of the polarizing plate 8 in FIG. 2 is a vertical direction, which is a direction parallel to the horizontal vibration component d of the reflected light b with respect to the sample 3 to be measured. The half-wave plate 4 in FIG. 2 is a kind of retardation film. As can be seen in FIG. 2, for the reflected light b from the surface of the sample 3 to be measured,
The half is arranged so that only the half-wave plate 4 and the polarizing plate 8 pass, and the other half only passes through the polarizing plate 8, so that the center of the reflected light c after passing through the polarizing plate 8 is incident on the center of the PSD 6. . At this time, the direction of the half-wave plate 4 is such that the oscillation direction of the s-wave h included in the reflected light from the sample to be measured is rotated by about 90 ° as shown in FIG. It is desirable to set the shaft 9 at an angle of θ = 45 ° with respect to the vibration direction of the s-wave h).

FIG. 4 shows a component of the reflected light b from the sample 3 shown in FIG. 2 that passes through both the half-wave plate 4 and the polarizing plate 8. The reflected light b before passing through the half-wave plate 4 and the polarizing plate 8 is composed of irregularly reflected light j and regular reflected light k. The irregularly reflected light j is reflected light having various vibration directions including the s-wave and the p-wave, and the existence probabilities of the s-wave and the p-wave are almost equal.
The specularly reflected light k is composed of only s waves. 1/2 wave plate 4
Since the irregularly reflected light 1 that has passed through changes the oscillating direction by 90 ° for both the s-wave and the p-wave, the s-wave having a vibration direction perpendicular to the transmission direction is suppressed when passing through the subsequent polarizing plate 8. , P-waves having parallel vibration directions can pass. On the other hand, the specularly reflected light m that has passed through the half-wave plate 4 changes the vibration direction by 90 °, so that it has a vibration direction perpendicular to the transmission direction of the polarizing plate 8 at the subsequent stage, and the passage is suppressed.
Therefore, the component passing through both the half-wave plate 4 and the polarizing plate 8 for the reflected light b from the sample 3 to be measured is only the irregularly reflected light (p-wave) n.

FIG. 5 shows a component of the reflected light b from the sample 3 shown in FIG.
The reflected light b before passing through the polarizing plate 8 is composed of irregularly reflected light j and specularly reflected light k, as in FIG. When the irregularly reflected light j passes through the polarizing plate 8, the transmission of a p-wave having a vibration direction perpendicular to the transmission direction is suppressed, but the transmission of an s-wave having a vibration direction parallel to the transmission direction is suppressed. It becomes possible. on the other hand,
The regular reflection light k has a vibration direction parallel to the transmission direction of the polarizing plate 8 and can pass therethrough. Therefore, components of the reflected light b from the sample 3 to be passed through only the polarizing plate 8 are specularly reflected light (s-wave) p and irregularly reflected light (s-wave) o.

For this reason, as shown in FIG. 2, of the light incident on the PSD 6, as shown in FIG. 2, the right region is the reflected light f composed of the specularly reflected light (s-wave) and the irregularly reflected light (s-wave) transmitted only through the polarizing plate 8, The left area is the reflected light g of only the irregularly reflected light (p-wave) that has passed through both the half-wave plate 4 and the polarizing plate 8, and the irradiation light amount and irradiation position of these reflected lights f and g and the distance between the electrodes of the PSD 6. Current determined by resistance etc. (I _PSD 1, I _PSD 2)
Is obtained from the terminal of PSD6.

FIG. 6 is an example of a signal processing block for performing signal processing on the output currents (I _PSD 1 and I _PSD 2) of the _PSD 6 in FIG. 2 and obtaining an output voltage corresponding to the amount of specular reflection. The voltage Vcc is applied to the cathode terminal 10 of the PSD 6 in advance.
Is applied. Anode terminals 11 and 12 of PSD 6
The current (I) due to the reflected light c received by the PSD 6
_PSD 1 and I _PSD 2) will flow out. Current I
_PSD 1 and I _PSD 2 are the load resistances RL 1 and R
Are converted into voltages V _PSD 1 and V _PSD 2 by L2,
The signals are separately amplified by signal amplifier circuits 13 and 14 at the next stage. In the example of FIG. 6, the amplification degrees of the signal amplification circuits 13 and 14 are both 1
Although it is set to 000, the amplification degree may be different for convenience of the operation in the signal operation circuit at the subsequent stage. The voltages extracted from the signal amplification circuits 13 and 14 are calculated by a signal calculation circuit 15 at the subsequent stage according to a formula determined by the irradiation light amount and the irradiation position of the PSD 6, the resistance between the electrodes of the PSD 6, and the like. Since an output voltage corresponding to the amount of reflected light is obtained, the glossiness can be measured from the magnitude of this voltage value.

Second Embodiment In the gloss sensor of FIG. 2 in the first embodiment, the transmission direction of the polarizing plate 8 is set to the vertical direction (parallel to the s-wave). However, the case where the transmission direction of the polarizing plate 17 is arranged in the horizontal direction (perpendicular to the s-wave) as shown in FIG. 7 can also be used as a gloss sensor. For the reflected light b before passing through the half-wave plate 4 and the polarizing plate 17 shown in FIG. 7, a vertical vibration component e with respect to the sample 3 to be measured is a p-wave, and a horizontal vibration component d, as in FIG. Is an s-wave.

In the case of FIG. 7, the reflected light b from the sample 3 is measured.
The component that passes through both the half-wave plate 4 and the polarizing plate 17 is specularly reflected light (s-wave) and diffusely reflected light (s-wave), and the component that passes only through the polarizing plate 17 is diffusely reflected light (p-wave). . (1
The concept of reflected light passing through the half-wave plate 4 and the polarizing plate 17 or only the polarizing plate 17 is the same as in FIGS. )

Therefore, as shown in FIG. 7, of the light incident on the PSD 6, as shown in FIG. 7, the right region is the reflected light q of only the irregularly reflected light (p-wave) passing only through the polarizing plate 17, and the left region is the half-wave plate. Specularly reflected light (s-wave) that has passed through both 4 and the polarizing plate 17
And irregularly reflected light (s-wave), and the reflected light r is composed of the irradiation light quantity and irradiation position of the reflected light q and r, and the current (I PSD1, I _PSD) determined by the resistance between the electrodes of the _PSD 6.
_PSD 2) is obtained from the terminal of PSD6. Therefore,
From PSD6 output current _{(I PSD 1, I PSD 2} ),
By performing calculations determined by the irradiation light amount, the irradiation position, the resistance between the electrodes of the PSD 6, and the like using the same signal processing block as in FIG. 6, an output voltage corresponding to the regular reflection light amount is obtained. The degree of gloss can be measured from the magnitude of.

Third Embodiment In the first and second embodiments, about half of the reflected light b from the sample 3 to be measured is rotated by 90 ° in the vibration direction by using the half-wave plate 4. Exactly 90
Even if rotation is not possible, a similar gloss sensor can be formed using a transparent film that exhibits a birefringence effect.

FIG. 8 shows a case where a transparent film 18 is used instead of the half-wave plate 4 in FIG. As the transparent film 18 in FIG. 8, a film exhibiting a birefringence effect is used. On the light emitting side, the same one as in FIG. 1 is used. As to the reflected light b before passing through the transparent film 18 and the polarizing plate 17 shown in FIG.
The vertical vibration component e is a p-wave, and the horizontal vibration component d is an s-wave. (In FIG. 8, the transmission direction of the polarizing plate 17 is set to the horizontal direction, but the case where the transmission direction of the polarizing plate is set to the vertical direction can be considered in the same manner as described below.)

The transmission direction of the polarizing plate 17 shown in FIG. 8 is the horizontal direction, which is the horizontal vibration component d with respect to the sample 3 to be measured.
And the direction perpendicular to it. As shown in FIG. 8, half of the reflected light b from the surface of the sample 3 to be measured passes through the transparent film 18 and the polarizing plate 17, and the other half passes only through the polarizing plate 17, and passes through the polarizing plate 17. It is arranged so that the center of the later reflected light c is incident on the center of the PSD 6. At this time, the direction of the transparent film 18 is set such that the vibration direction of the s-wave h contained in the reflected light from the sample to be measured is approximately α as shown in FIG.
° Installed to rotate. At this time, it is desirable to set the optical axis 19 of the transparent film 18 so that the rotation angle α ° in the vibration direction becomes as large as possible.

FIG. 10 shows a component of the reflected light b from the sample 3 shown in FIG. 8 that passes through both the transparent film 18 and the polarizing plate 17. Transparent film 18 and polarizing plate 1
7 are irregularly reflected light j and specularly reflected light k.
It is composed of Since the irregularly reflected light u that has passed through the transparent film 18 changes the oscillation direction of α ° for both the s-wave and the p-wave, the irregular reflection light u having the oscillation direction perpendicular to the transmission direction (s-wave ) × cos ² α and diffuse reflection (p wave) × sin ² α are suppressed from passing, and diffuse reflection (s wave) × sin ² α and diffuse reflection (p wave) having parallel vibration directions are performed.
× cos ² alpha becomes possible passage. At this time, the existence probabilities of the s-wave and the p-wave included in the irregularly-reflected light are almost equal, and the irregular reflection (s-wave) 反射 the irregular reflection (p-wave) makes the irregularly-reflected light passing through both the transparent film 18 and the polarizing plate 17. Is

[0021]

(Equation 1)

It can be arranged as follows. On the other hand, the specularly reflected light v that has passed through the transparent film 17 changes the oscillation direction by α °, so that the specularly reflected light (s-wave) × sin ^2, which is a component parallel to the polarizing plate 18 when passing through the latter polarizing plate 17. Only α can pass. Therefore, the component of the reflected light b from the sample 3 to be measured that passes through both the transparent film 18 and the polarizing plate 17 is specularly reflected light (s-wave) × sin ² α and diffusely reflected (s-wave).

FIG. 11 shows a component of the reflected light b from the sample 3 to be measured shown in FIG. The reflected light b before passing through the polarizing plate 17 is composed of irregularly reflected light j and specularly reflected light k, as in FIG. When the irregularly reflected light j passes through the polarizing plate 17, the passage of an s-wave having a vibration direction perpendicular to the transmission direction is suppressed, whereas the passage of a p-wave having a vibration direction parallel to the transmission direction is suppressed. It becomes possible. On the other hand, since the specular reflection light k has a vibration direction perpendicular to the transmission direction of the polarizing plate 17, the passage of the light is suppressed. Therefore, the reflected light b from the sample 3 to be measured 3
The component passing only through the above becomes irregularly reflected light (p-wave) y.

Therefore, as shown in FIG. 8, of the light incident on the PSD 6, as shown in FIG. 8, the right region is the reflected light s of only the irregularly reflected light (p-wave) that has passed only through the polarizing plate 17, and the left region is the transparent film 18 and polarization Specularly reflected light (s) passing through both of the plates 17
(Wave) × sin ² α and reflected light t composed of irregularly reflected light (s-wave)
And the currents (I _PSD 1, I _PSD 1) determined by the irradiation light amount and the irradiation position, the resistance between the electrodes of _PSD 6, and the like.
_PSD 2) is obtained from the terminal of PSD6. Therefore,
From PSD6 output current _{(I PSD 1, I PSD 2} ),
By performing calculations determined by the irradiation light amount, the irradiation position, the resistance between the electrodes of the PSD 6, and the like using the same signal processing block as in FIG. 6, an output voltage corresponding to the regular reflection light amount is obtained. Gloss can be measured from large and small.

In Examples 1, 2, and 3, the light transmittance of the half-wave plate 4 and the transparent film 18 was 100%, and the light transmittance of the polarizing plates 8 and 17 in the direction perpendicular to the transmission direction was 0. %, Which is different from the actual case and when the difference cannot be ignored, it is necessary to correct the calculation in the signal processing block shown in FIG.

In Examples 1, 2, and 3, the center of the reflected light b from the sample 3 to be measured and the phase difference film (the half-wave plate 4, the transparent film 18, etc.), the polarizing plates 8, 17 or the PSD 6 Even if the positional relationship is slightly different, it can be corrected by calculation in the signal processing block in FIG.

In the first, second and third embodiments, the non-divided PSD
However, it is also possible to use a split type (two-division, four-division, etc.) PSD.

[0028]

As described above, according to the present invention, (irregularly reflected light) / (specularly reflected light and irregularly reflected light) are determined according to the amounts of the respective reflected light components regardless of the color density of the object surface. By taking out and comparing as two current values,
The glossiness of the object surface can be known, and the glossiness can be determined. At this time, without using expensive semiconductors such as color sensors and linear image sensors, PSDs, retardation films,
An inexpensive gloss sensor can be provided with a simple configuration such as a polarizing plate.

[Brief description of the drawings]

FIG. 1 is an embodiment of a gloss sensor using the present invention.

FIG. 2 shows details on the light receiving side of the gloss sensor of FIG. 1;

FIG. 3 is a diagram showing that the s-wave oscillation direction is rotated by 90 ° by a half-wave plate used in the gloss sensor of FIG. 2;

FIG. 4 is a diagram illustrating a reflection component that passes through both a half-wave plate and a polarizing plate in the gloss sensor of FIG. 2;

FIG. 5 is a diagram illustrating a reflection component that passes only through a polarizing plate in the gloss sensor of FIG. 2;

FIG. 6 shows a signal processing block for performing signal processing on a PSD output current by the gloss sensor of FIG. 2 and extracting an output voltage corresponding to the amount of specular reflection.

7 shows details of the gloss sensor of FIG. 1 on the light receiving side of the gloss sensor with the transmission direction of the polarizing plate being the horizontal direction.

FIG. 8 shows details of a light receiving side of the gloss sensor using a transparent film exhibiting a birefringence effect instead of the half-wave plate in the gloss sensor of FIG.

FIG. 9 is a diagram showing that the vibration direction of the s-wave is rotated by α ° by the transparent film used in the gloss sensor of FIG.

FIG. 10 is a diagram illustrating a reflection component passing through both a transparent film and a polarizing plate in the gloss sensor of FIG. 8;

FIG. 11 is a diagram illustrating a reflection component passing only through a polarizing plate in the gloss sensor of FIG. 8;

[Explanation of symbols]

 Reference Signs List 1 light source 2 condenser lens 3 sample to be measured 4 1/2 wavelength plate (retardation film) 5 polarizing plate 6 PSD 7 reflected light irradiated on PSD 8 polarizing plate (transmission direction: vertical) 9 1/2 wavelength plate Optical axis 10 PSD cathode terminal 11 PSD anode terminal 12 PSD anode terminal 13 V_PSD1 signal amplification circuit 14 V_PSD2 Signal amplification circuit 15 Signal operation circuit 16 Output terminal of signal processing block 17 Polarizer (transmission direction: horizontal) 18 Transparent film having birefringence effect 19 Optical axis of transparent film a Light incident on sample 3 to be measured b Reflected light from the measurement sample 3 c Reflected light after passing through the polarizing plate 8 or the polarizing plate 17 d Vibration component in the horizontal direction with respect to the measurement sample 3 e Vibration component in the vertical direction with respect to the measurement sample 3 f In the right region of the PSD 6 Specular reflected light (s-wave)
Diffusely reflected light (s-wave) g Diffusely reflected light (p-wave) applied to the left area of PSD 6 h s-wave before passing through half-wave plate 4 i s-wave after passing through half-wave plate 4 j Diffusely reflected light k included in reflected light b from sample 3 to be measured k Regularly reflected light included in reflected light b from sample 3 to be measured l Diffusely reflected light after passing through half-wave plate 4 m 1 / 2-wave plate Specularly reflected light after passing through No. 4 Diffusely reflected light after passing through both the half-wave plate 4 and the polarizing plate 8
(P-wave) o Diffusely reflected light (s-wave) after passing only through the polarizing plate 8 p Regularly reflected light (s-wave) after passing through only the polarizing plate 8 q Diffusely reflected light (p) applied to the right area of the PSD 6 Wave) r Specularly reflected light (s wave) applied to the left area of PSD 6
Diffusely reflected light (s-wave) s Diffusely reflected light (p-wave) applied to the right area of PSD 6 t Regularly reflected light (s-wave) applied to left area of PSD 6 ×
sin2α and irregularly reflected light (s-wave) u irregularly reflected light after passing through the transparent film v specularly reflected light after passing through the transparent film w forward / reverse after passing through the transparent film 18 and the polarizing plate 17
Light (s-wave) x sin²α  x turbulence after passing through the transparent film 18 and the polarizing plate 17
Emitted light (s-wave) y Diffusely reflected light (p-wave) after passing through the polarizing plate 17

Claims (3)

(57) [Claims] An object is irradiated with light rays included in an infrared to visible region and reflected, and position detection is performed by dividing the light into reflected light passing through a retardation film and a polarizing plate and reflected light passing through a polarizing plate. A method for measuring the glossiness of the surface of an object, comprising detecting a sensor and processing an output current according to the amounts of the two reflected lights. 2. The method according to claim 1, wherein the retardation film is a half-wave plate or a transparent film exhibiting a birefringence effect. 3. The method according to claim 1, wherein the two reflected lights are specularly reflected light, irregularly reflected light, and irregularly reflected light.