JPH06221818A - Measuring apparatus of thickness - Google Patents

Abstract

PURPOSE:To prolong the lifetime of a chopper and to make an apparatus small in size by a method wherein a detection signal obtained from a measured light is made an intermittent signal by an optical scanner having a total reflection mirror disposed on the optical axis and changing an optical path periodically in an arbitrary direction by shaking the mirror, and by a means for intercepting a part of the optical path. CONSTITUTION:A light 2b which is emitted from a light source 2 containing a wavelength to be transmitted through a material 1 to be measured and a wavelength component to be absorbed by the material and is transmitted through the material 1 is made a measured light 2c being vibrated in reciprocation in the vertical direction by the motion of an optical scanner 12. A measured light 2d intercepted by a light- intercepting plate 14 and passed through a condenser lens 15 is divided in two wavelength components by a beam splitter 16 and electric signals generated from the condensed light 2d arriving at photoelectric sensors 7a and 7b become rectangular waves. The outputs of the sensors 7a and 7b obtain a signal p1 or p2 in a time zone t1 in which a light 2c passes the light-intercepting plate 14, while an output signal is made zero by the light-intercepting plate 14 in a time zone t2 in which the light 2c is directed downward. By an indicating device 17 of thickness shown by p1/p2, the thickness of the material 1 is measured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness measuring device for optically measuring the thickness of a film sheet material, a coating material or the like.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, JP-A-61-28700.
It is a schematic diagram which shows the structure of the conventional infrared thickness measuring device described in the publication 5, 1 is a film-sheet-like measured material flowing in a belt shape, 2 is this measured material 1 A light source of the emitted light 2a to be emitted, 3 is a rotary chopper provided with a slit for chopping the emitted light 2a, 4 is a motor for rotationally driving the rotary chopper 3, 5
Is a synchronous detector that extracts a signal synchronized with the rotation of the rotary chopper 3, 6 is a convex lens that collects the transmitted light 2b that has passed through the measured material 1 on the photoelectric sensors 7a and 7b, and 8 is the transmitted light 2b.
A beam splitter for splitting the measurement light into measurement light 2Ba and 2Bb,
Reference numerals 9a and 9b are optical bandpass filters 10a and 10 for extracting wavelength light in a specific region from the measurement light 2Ba and 2Bb.
Reference numeral b denotes a signal processor 11 for processing the output signals of the photoelectric sensors 7a and 7b, and a switch for interlocking with the output signal of the synchronization detector 5.

Next, the operation will be described. The transmitted light 2b which is a part of the emitted light 2a of the light source 2 is finally caught by the photoelectric sensors 7a and 7b. When the light is transmitted through the measured material 1, various transmission is performed depending on the material of the film sheet. Show the characteristics. For example, one of the transmission characteristics shown in FIG. 17 is that the attenuation in the measured material 1 is large when the wavelength is λ ₁ , but there is no large drop in other regions, and the same transmittance α ₂ is obtained at the wavelength λ ₂ as well. Shows. Transmittance at a wavelength λ ₁ α ₁
Is widely known to change depending on the thickness of the material to be measured 1, and the transmittance also changes depending on the degree of coloring of the material to be measured 1, temperature and humidity, and surface roughness. However, if the ratio of α ₁ / α ₂ is taken, information other than the thickness of the material to be measured 1 is canceled out, and the accuracy of thickness measurement is improved.

The thickness measuring device shown in FIG. 13 is constructed on the basis of the above idea. The band filter 9a transmits only the light of the wavelength λ ₁ and the band filter 9b transmits the wavelength λ ₂
Only the light of is transmitted. As a result, the rotary chopper 3
If the number of slits provided in the
The time waveform of the output signal of FIG. 15A is the measurement light 2Ba, 2
Signal processor 10a, 1 which has detected Bb and has been subjected to signal processing
The output signals of 0b are shown in FIGS. 15-B and 15-C, respectively. Due to the operation of the change-over switch 11 synchronized with the output signal of the synchronization detector 5, the output signal of the thickness measuring apparatus has the amplitude P ₁ shown in FIG. 15-B in the section of S ₁ in FIG. 15-A and S ₂ The amplitude P ₂ shown in FIG.
Becomes Therefore, the thickness of the material to be measured 1 can be known by obtaining the ratio of P ₁ and P ₂ . The main feature here is that the measurement light transmitted through the material to be measured 1 is weak, so that the operation of the rotary chopper 3 causes the measurement light shown in FIG.
This is because a special signal shown in B and C is converted and then synchronously rectified using a lock-in amplifier or the like to equivalently increase the S / N ratio.

[0005]

Since the conventional thickness measuring device is constructed as described above, the rotary chopper in which the chopper for setting the fragment wavelength to increase the S / N ratio is interlocked with the drive motor. However, there is a problem that a bearing is required for the drive system, the S / N ratio of the measurement system is lowered due to the limit of service life or vibration, and the rotating part becomes an obstacle to downsizing.

The present invention has been made in order to solve the above-mentioned problems, and provides a thickness measuring apparatus for extending the life of the chopper, improving the measuring accuracy by highly accurate chopping operation, and further making the apparatus compact. The purpose is to get.

[0007]

[Means for Solving the Problems] Claim 1 according to the present invention
The thickness measuring device has a light source that transmits the emitted light to the material to be measured, and a total reflection mirror in which the inclination of the reflecting surface always changes with respect to the incident light on the optical axis of the transmitted light, and the optical axis after reflection is A wavelength converter that consists of an optical scanner that both amplitudes the optical path in the center and a light-shielding unit that shields the lower side of the optical axis of the optical path. A beam splitter that selectively changes the optical path of light and a light receiving unit that is arranged corresponding to the selected optical path and that has photoelectric sensors having different wavelength characteristics, and that outputs an electric signal of a measurement wavelength and a comparison wavelength from the measurement light, It is configured by a thickness indicating device which inputs both electric signals and calculates the ratio of each amplitude.

A thickness measuring device according to a second aspect of the present invention is the first aspect.
The inner condensing lens described in (1) is composed of first and second convex lenses arranged in series close to or in contact with each other.

Further, the thickness measuring device of claim 3 is the same as that of claim 1.
The inner light-shielding means described in (1) is composed of a lens having a light-shielding coating on the lower side of the optical axis of the condenser lens or a half-shaped lens having the lower side cut.

A thickness measuring device according to a fourth aspect of the present invention is the first aspect.
The internal wavelength conversion unit described in 1 changes the refraction index by changing the degree of refraction depending on the coarse density of the oscillation frequency of the transmitted light that is generated inside, and outputs the acousto-optical element that swings the optical path around the optical axis in a swinging manner. It is configured by a light-shielding device that shields the lower side of the shaft.

A thickness measuring device according to a fifth aspect of the present invention is the first aspect.
Or 4, the first cylindrical lens is provided between the light source and the material to be measured in proximity to the transmission side of the material to be measured, and the cylindrical lens is provided orthogonal to the optical axis, and the second lens is provided.
The second condensing lens is arranged at a position corresponding to the second cylindrical lens of the cylindrical lens.

A thickness measuring device according to a sixth aspect of the present invention is the fifth aspect.
The first cylindrical lens is replaced by a total reflection mirror in which the inclination of the reflecting surface is constantly changed with respect to the incident light on the optical axis, and the optical path of the emitted light is moved periodically in the width region of the material to be measured.
It is composed of the optical scanner.

[0013]

In the thickness measuring apparatus according to the present invention, since the fragment wavelength is obtained by the optical scanner for angularly oscillating the optical path of the measuring light and the light shielding means for intermittently shielding the optical path, the driving is small and the failure and the vibration are reduced.

Further, the focal point of the first convex lens is brought closer by the second convex lens, which enables downsizing of the apparatus.

Further, the first cylindrical lens irradiates the emitted light as diffused light to a wide range of the material to be measured, and enables the immediate measurement of the average thickness of the material to be measured.

Further, the second optical scanner can continuously scan by moving the optical path of the emitted light in the width direction of the material to be measured so that the thickness of the material to be measured can be continuously measured in a wide range.

[0017]

【Example】

Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a schematic diagram showing a configuration of a thickness measuring apparatus according to Embodiment 1 of the present invention, FIG. 2 is an operation explanatory diagram functionally showing the optical scanner in FIG. 1, and FIG. 3 is an output waveform of a photoelectric sensor in FIG. It is a waveform diagram shown. In the figure, 1
Reference numeral 2 denotes a transmitted light 2 emitted from the light source 2 and transmitted through the measured material 1.
This is an optical scanner equipped with a small mirror for optically scanning b. FIG. 2 shows a detailed structural example of the optical scanner. In the figure, 12a is an elliptical electromagnetic coil, 12b is a shaft fixed to this coil 12a,
Reference numeral 12c is a small mirror attached to the shaft 12b, and the whole is designated by a flexible coil spring 12d, for example, so as to be rotatable about the long axis of the shaft 12b. Reference numeral 13 is a driver for driving an optical scanner, such as an AC amplifier, 2c is measurement light whose optical path is oscillated in both directions by the optical scanner 12, 14 is a light-shielding plate which shields half of both amplitudes of the measurement light 2c, 15 Is the measuring light 2
It is a convex lens or a convex lens system that collects c. In addition,
The center a of the optical scanner 12 is placed on the optical axis when the optical scanner 12 is not swinging, that is, the reflecting surface is not tilted.
The upper end of the light shielding plate 14 and the center O of the convex lens 15 are arranged in a straight line. Reference numeral 16 denotes a beam splitter that divides the condensed measurement light 2d that has passed through the convex lens 15 into two.

The photoelectric filters 7a and 7b are the same as the conventional optical filters 9a and 9b.
The output signals of a and 7b are input to the thickness indicating device 17, subjected to signal processing, and then synchronously rectified with reference to the synchronizing signal from the oscillator 13a to instruct calculation of a target thickness. A lock-in amplifier is a general-purpose device for the thickness indicating device.

The operation of the optical scanner shown in FIG. 2 will be described together with the operation of the thickness measuring apparatus shown in FIG. When an alternating current flows into the coil 12a installed in the DC magnetic field (N → S), the upper side and the lower side of the coil 12a flow in the opposite directions, so that the force according to Fleming's left-hand rule is
The upper side and the lower side of the coil 12a work in opposite directions, and the small mirror 12c is rotated around the longitudinal direction of the shaft 12b.
Changes the inclination with respect to the incident light. By the operation of the optical scanner 12, the transmitted light 2b becomes the measuring light 2c which oscillates in both directions along the optical path on one plane. Due to the light shielding by the light shielding plate 14, a photoelectric sensor 7a, condensing measurement light 2d reaching the 7b becomes a rectangular waveform as shown in FIG. 3, the measuring beam 2c time zone passes through the light shielding plate 14 t ₁ Obtains the signal of P ₁ or P ₂ and the measuring light 2c is directed downward and the light shield plate 14
The output signal becomes zero in the time period t ₂ which is interrupted.

The signals shown in FIGS. 3A and 3B are photoelectric sensors 7a,
7b, and the thickness of the measured material 1 is measured by the P ₁ / P ₂ thickness indicating device 17. Instead of the optical scanner 12, it is of course possible to use a component having a simple structure similar to the structure of the optical scanner 12, such as a vibrator of a direct-write electromagnetic oscillograph,
The whole structure is simple and compact.

Example 2. In addition, here, with the configuration of the first embodiment, selection of the optimum state for the position of the convex lens 15 is performed in the second embodiment.
As described below. When the convex lens 15 or the convex lens system is installed at a position shorter than the focal position of the convex lens 15 or the convex lens system, the measurement light 2c passing through the convex lens 15 is condensed on the photoelectric sensors 7a and 7b as shown in FIG. 4A. Spread without. Similarly, in FIG. 4B, when the position a of the optical scanner is set to the focal position of the convex lens, the light passing through the convex lens does not reach the photoelectric sensor. Also, FIG.
As shown in C, when the position a of the optical scanner is between the focal positions f and 2f, the light passing through the convex lens tends to be focused, but the focusing distance becomes extremely long, which is not suitable for downsizing the optical system. Is. However, when a is located at a position twice the focal length, the light passing through the convex lens is focused at the position -2f in FIG. The arrangement of each component under this condition is the best condition for making the optical system compact. Even when there is a at a position on the left side of 2f as shown in FIG. 4-E, the light passing through the convex lens is -f.
Although the light is condensed between 2f and -2f, the optical path length becomes long as in the case of FIG. 4C, which is not suitable for making the optical system compact.

Example 3. In order to make the optical path system compact, the convex lens 15 is replaced by the first convex lens 1 as shown in FIG.
5a and the second convex lens 15b are combined, and the distance between the optical scanner 12 and the first convex lens 15a is arranged according to the focal length of the lens.
5b is arranged in contact with the first convex lens 15a, and the photoelectric sensors 7a, 7 are aligned with the focal length of the second convex lens 15b.
By arranging the tip positions b ₁ and b ₂ of b, the optical path system can be made compact. When the emitted light 2a from the light source 2 is a parallel light having a finite diameter, the output light of the first convex lens 15a is parallel to the optical axis O ₁ b _2, but its diameter is reduced as the distance from the lens increases. Therefore, if the second convex lens 15b is installed away from the first convex lens 15a, the measurement light cannot be narrowed down on the tips b ₁ and b ₂ of the photoelectric sensors 7a and 7b, and the photoelectric sensor 7a, 7b is weak even if it is weak. Sensors 7a, 7
The output signal of b is extremely small, and the accuracy of thickness measurement is greatly reduced. Therefore, by arranging the position of the second convex lens 15b in contact with the first convex lens 15a as much as possible, the measurement light is focused on the tips b ₁ and b ₂ of the photoelectric sensors 7a and 7b and is focused. It will be possible. That is, the optical path system can be made compact, and a thickness measuring device with good photoelectric detection efficiency can be obtained.

Example 4. In the thickness measuring device of the first embodiment, the tilt change angle of the optical scanner 12 is vertically symmetrical with respect to the optical axis, and the ratio of t ₁ and t ₂ of the rectangular wave in FIG. 3 is the same,
This is the ideal situation. In a thickness indicating device such as a lock-in amplifier, the measured value of the thickness changes if the ratio of t ₁ and t ₂ changes to some extent, so it must be kept constant. However, the above t ₁ and t ₂ may differ due to the non-linearity of the output voltage of the driver 13, the change of the neutral point of the optical scanner, and the positional deviation of each component due to the temperature change. As a countermeasure in this case, the light shielding plate 14 in FIGS. 1 and 5 has a structure in which fine movement adjustment is possible in the arrow direction.
As a result, exactly half of the measuring light whose optical path is oscillated in both directions by the operation of the optical scanner 12 is guided to the convex lens 15, and the ratio of t ₁ and t _{2 in} FIG. Can be secured.

Example 5. As described above, in FIGS. 1 and 5 of the first and fifth embodiments, the cross section of the measuring light that oscillates both sides of the optical path by the optical scanner 12 is a straight line or an elongated rectangle, so that the front surface of the circular convex lens is used. It has not been. Therefore, the cylindrical lens 18 shown in FIG. 6-A on the front side and the cross-section shown in FIG. 6-B may be used. By adopting this cylindrical lens 18, the lens holder has a simple structure, and the overall size and weight are small, which facilitates manufacturing and assembly.

Example 6. Further, in each of the above embodiments, the light shielding plate 15 is provided separately from the convex lens or the convex lens system.
As shown in FIG. 7, the front half of the lens may be coated with a light blocking coating 19 to block the measurement light 2c. In this case, by making the lens itself move in the direction of the arrow in the figure, the time width of the measuring light intended for Example 4 (t ₁ and t _{2 in} FIG. 3).
Can be adjusted. This simplifies the structure because the light shield plate can be omitted.

Example 7. In the above embodiment, the condenser lens behind the measurement light has a structure in which the lens is arranged both above and below the optical axis, but as shown in FIG. . This makes it possible to further reduce the size and weight of the structure.

Example 8. In each of the above embodiments, the method of using the optical scanner 12 is used as the swinging method of the measuring light, but the acousto-optical element 21 is arranged as shown in FIG. The direction of the light 2c may be changed. In FIG. 9, a signal of a high frequency oscillator is amplified by an amplifier 23 and a voltage is applied to the electrode 21a to generate a compressional wave in the acousto-optic element 21, and the input light is reflected and refracted depending on the degree of the compressional density. Since the degree of density is determined by the oscillation frequency of the high-frequency oscillator 22, it is possible to change the refraction angle of the input light and swing the optical path of the measurement light in an oscillating manner by continuously changing the oscillation frequency. .

Example 9. When the measurement light (input light) is oscillated in the above embodiment, the voltage waveform applied to the optical scanner 12 is not specified, and a general sine wave is assumed to configure the whole and the description is added. The output wave of the oscillator 13a is a rectangular wave in FIG. 10A, and the optical scanner 12 is oscillated in a rectangular shape in FIG. 10B.
By this, the output signals of the photoelectric sensors 7a and 7b become good. That is, the photoelectric sensor 7 described in the fourth embodiment
Regarding the problem with respect to the deviation of t ₁ and t ₂ of the output signals of a and 7b, since the measurement light 2c stays in the upper optical path and the lower optical path for a long time and passes through the center of the lens for a short time,
This deviation can be almost eliminated, and P ₁ / P ₂ in FIG. 3 can be measured more accurately, which improves the accuracy of thickness measurement.

Example 10. In the above embodiment, the spot-like light is emitted to one place on the measured material 1 to measure the thickness, and the light source 2 is used to measure another position of the measured material 1 flowing in a belt shape. , And the structure for moving the photoelectric detection system as a whole was used as a basic idea, but a linear emission light was applied in a direction orthogonal to the flow direction of the measured material 1 and the transmitted light of this light was detected as measurement light. If the thickness is measured, it is possible to measure the average value of the thicknesses of the light emitting portions to the measured material 1. This embodiment is shown in FIG. In the figure, the light source 2
The linear or cylindrical light emitted from the first cylindrical lens 24 is incident on the first cylindrical lens 24, and the strip-shaped and isosceles triangular diffused light 24a is applied to the measured material 1. The transmitted light is condensed by the second cylindrical lens 25 having a narrow width, the concave lens 26 and the like are used to enter the optical scanner 12 and the like similar to the above-described embodiment, and the thickness is measured by signal processing. Thereby, the average thickness of the region where the measured material 1 in FIG. 11 is irradiated with light can be measured.

Example 11. In the above examples, the method of irradiating light on one point of the material to be measured 1 or diffusing the light linearly to measure the thickness was adopted, but the first cylindrical lens in FIG. 12 instead of FIG.
The second optical scanner 24 is installed as shown in, and the inclination of this optical scanner is changed in a sinusoidal shape with respect to the optical axis.
Emitting light 2a is applied in a sinusoidal manner on the material to be measured 1 flowing in the direction perpendicular to the paper surface, and the transmitted measuring light 2b is guided to a concave lens 26 by a rod-shaped second cylindrical lens 25. The second optical scanner 27, the second cylindrical lens 25, and the concave lens are arranged in consideration of the focal point of the second cylindrical lens 25 as in the arrangement of the convex lens 15 in FIG. The light 2a will be guided to the concave lens 26 regardless of the position on the measured material 1. The configuration and operation after the concave lens are the same as in the first embodiment, and the thickness of the measured material 1 can be measured. According to this embodiment, the thickness can be measured over the entire area of the material to be measured without moving the light source and the optical path detection system.

[0031]

As described above, according to the present invention, the light source for transmitting the emitted light to the material to be measured, and the total reflection mirror in which the inclination of the reflecting surface always changes with respect to the incident light on the optical axis of the transmitted light are provided. A wavelength conversion unit that has an optical scanner that both swings the optical path around the optical axis after reflection and a light shielding unit that shields the lower side of the optical axis of the optical path, and that makes the transmitted light chopped measurement light. ,
It consists of a beam splitter that selectively changes the optical path of the measurement light that is condensed by the condenser lens and enters, and a photoelectric sensor that is arranged corresponding to the selected optical path and has different wavelength characteristics. Since it is composed of a light receiving part that outputs an electric signal of a wavelength and a thickness indicating device that inputs both electric signals and calculates the ratio of each amplitude, a fragment wavelength can be obtained by the optical scanner and the light shielding means and the driving system is reduced. There is an effect that a thickness measuring device having a long life and high measurement accuracy can be obtained.

Further, since the condensing lens is composed of the first and second convex lenses which are arranged close to or in contact with each other in series, the focal positions are brought close to each other, and the thickness measuring device which enables downsizing of the device is obtained. is there.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a thickness measuring device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram functionally showing the optical scanner in FIG.

FIG. 3 is a waveform diagram showing an output waveform of the photoelectric sensor in FIG.

FIG. 4 is an explanatory diagram of a light collecting operation according to the second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a partial configuration according to a third embodiment of the present invention.

FIG. 6 is an outline view showing the shape of parts in Embodiment 5 of the present invention.

FIG. 7 is a cross-sectional view showing a light shielding means in embodiment 6 of the present invention.

FIG. 8 is a cross-sectional view showing a light blocking means in a seventh embodiment of the present invention.

FIG. 9 is a schematic diagram showing a partial configuration according to an eighth embodiment of the present invention.

FIG. 10 is a waveform diagram for explaining the operation in the ninth embodiment of the present invention.

FIG. 11 is a schematic diagram showing a partial structure of a tenth embodiment of the present invention.

FIG. 12 is a schematic diagram showing a partial configuration of an eleventh embodiment of the present invention.

FIG. 13 is a schematic diagram showing a configuration of a conventional thickness measuring device.

FIG. 14 is an explanatory diagram showing an example of a transmitted light characteristic in the thickness measuring device.

FIG. 15 is a waveform diagram showing an output waveform in a conventional thickness measuring device.

[Explanation of symbols]

 1 material to be measured 2 light source 2a emitted light 2b transmitted light 2c measurement light (swing) 2d measurement light (condensing) 7 photoelectric sensor 12 optical scanner 12c total reflection mirror 14 light-shielding plate (light-shielding means) 15 convex lens (condensing lens) 15a 1st convex lens 15b 2nd convex lens 16 Beam splitter 17 Thickness indication device (arithmetic processing part) 19 Light-shielding coating 20 Half type lens 21 Acousto-optic element 24 1st cylindrical lens 25 2nd cylindrical lens 27 2nd Optical scanner

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[Procedure amendment]

[Submission date] September 20, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title of the invention Thickness measuring device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thickness measuring device for optically measuring the thickness of a film sheet material, a coating material or the like.

[0002]

2. Description of the Related Art FIG. 13 shows, for example, JP-A-61-28700.
It is a schematic diagram which shows the structure of the conventional infrared thickness measuring device described in the publication 5, 1 is a film-sheet-like measured material flowing in a belt shape, 2 is this measured material 1 A light source of the emitted light 2a to be emitted, 3 is a rotary chopper provided with a slit for chopping the emitted light 2a, 4 is a motor for rotationally driving the rotary chopper 3, 5
Is a synchronous detector that extracts a signal synchronized with the rotation of the rotary chopper 3, 6 is a convex lens that collects the transmitted light 2b that has passed through the measured material 1 on the photoelectric sensors 7a and 7b, and 8 is the transmitted light 2b.
A beam splitter for splitting the measurement light into measurement light 2Ba and 2Bb,
Reference numerals 9a and 9b are optical bandpass filters 10a and 10 for extracting wavelength light in a specific region from the measurement light 2Ba and 2Bb.
b is a signal processor for processing photoelectric sensor 7a, the output signal of 7b, 11 is a changeover switch which is linked to the output signal of the synchronous detector 5.

Next, the operation will be described. The emitted light 2a of the light source 2 is a wave peculiar to the material when passing through the measured material 1.
Absorbed for length. For example, the absorption characteristics of a material
In FIG. 14 showing a wavelength of the measured material 1 when lambda ₁
Absorption becomes maximum and a sharp drop occurs on the characteristic diagram.
On the other hand, at other wavelengths, the amount of transmitted light remains almost constant.
Become. Here, the absorption amount of light at the wavelength λ ₁ is
In principle, the light at this time changes because it changes according to the thickness of 1
The thickness of the material to be measured 1 can be obtained by measuring the transmittance α ₁ of
You can However, the transmittance of light depends on the coloring of the measured material 1.
It changes depending on the degree of temperature, temperature and humidity, surface roughness, etc.
Therefore, the wavelength that does not actually receive the absorption peculiar to the material, such as λ ₂
The transmittance α ₂ of the light is also measured and the ratio of the two α ₁ / α ₂ is calculated.
By measuring, the effects other than the above thickness are canceled out and the measured
The thickness of the material 1 is accurately measured.

[0004] The thickness measurement equipment shown in FIG. 13 are configured based on the above ideas, bandpass filter 9a wavelength λ
Only the light of ₁ is transmitted, and the bandpass filter 9b transmits only the light of wavelength λ ₂ . Time waveform of the output signal at this time synchronous detector 5 Figure 15-A, signal processor 10a, the output signal of 10b respectively, Figure 15-B, made in FIG 15-C.
Changeover switch 1 synchronized with the output signal of the synchronization detector 5
By the operation of No. 1, the output signal of the thickness measuring device has an amplitude P ₁ shown in FIG. 15-B in the section S ₁ in FIG. 15-A.
And the amplitude becomes P ₂ shown in FIG. 15-C in the section of S ₂ .
Therefore, the thickness of the material to be measured 1 can be known by obtaining the ratio of P ₁ and P ₂ . The major feature here is that the measurement light transmitted through the measured material 1 is weak, so after the conversion into the intermittent signals shown in FIGS. 15B and 15C by the operation of the rotary chopper 3, a lock-in amplifier or the like is used. Synchronous rectification is used to equivalently increase the S / N ratio.

[0005]

The conventional thickness measuring device is constructed as described above, and is cut off in order to increase the S / N ratio.
Chopper der because of rotary the connection signal is created Ru chopper is dynamic drive to the drive motor, the limit of the service life due to the drive system of the bearings, and low under a measuring system S / N ratio of the by vibration, also, rotation There was a problem such as an obstacle to miniaturization of the central device .

[0006] The present invention has been made to solve the above problems, and an object thereof is to obtain long life of the chopper, is et to the thickness measuring device compactness that Hakare devices.

[0007]

[Means for Solving the Problems] Claim 1 according to the present invention
Thickness measuring device absorbs the wavelength that the material under test transmits
A light source for emitting light containing a wavelength component, on the optical axis of the transmitted light
A total reflection mirror is arranged and its tilt angle is changed to
Shielding an optical scanner light path is periodically changed in any direction to the measuring light, disposed in a predetermined position of the optical path portion of the optical path
A light-shielding means for concealing the light and a condenser for condensing the measurement light at a predetermined position
Located behind the condensing lens and the wavelength of the measurement light.
A beam splitter for reflecting selectively separated by minutes,
Converts each of the separated measurement lights located at the focal point into an electrical signal
That a photoelectric sensor, the output signal of the photoelectric sensor of the measured material
And a thickness indicating device for calculating the thickness.

A thickness measuring device according to a second aspect of the present invention is the first aspect.
The inner condensing lens described in (1) is composed of first and second convex lenses arranged in series close to or in contact with each other.

Further, the thickness measuring device of claim 3 is the same as that of claim 1.
The inner shielding means in which the lens or the lower the lower is the light-shielding coating from the optical axis of the condensing lens is constituted by cut half-shaped lens according to.

A thickness measuring device according to a fourth aspect of the present invention is the first aspect.
In place of the internal optical scanner described in , replace the sound on the optical axis of the transmitted light.
Resonance optical element is provided and the optical path changes periodically in any direction.
It is configured to obtain measurement light .

A thickness measuring device according to a fifth aspect of the present invention is the first aspect.
Or 4, the first cylindrical lens is provided between the light source and the material to be measured in proximity to the transmission side of the material to be measured, and the cylindrical lens is provided orthogonal to the optical axis, and the second lens is provided.
The second condensing lens is arranged at a position corresponding to the second cylindrical lens of the cylindrical lens.

A thickness measuring device according to a sixth aspect of the present invention is the fifth aspect.
The first cylindrical lens is replaced by a total reflection mirror in which the inclination of the reflecting surface is constantly changed with respect to the incident light on the optical axis, and the optical path of the emitted light is moved periodically in the width region of the material to be measured.
It is composed of the optical scanner.

[0013]

The thickness measuring device in this invention is a total reflection mirror.
Oscillate and vibrate the optical path to periodically change the optical path in any direction.
The light shielding means for shielding a part of the optical scanner and an optical path that
The detection signal obtained from the measurement light becomes an intermittent signal.

Further, the focal point of the first convex lens is brought closer by the second convex lens, which enables downsizing of the apparatus.

[0015] Also, the first cylindrical lens to allow an immediate measurement of the average thickness of the irradiated on a wide range of the measured material to be measured material light emitted as emitting diffuse light.

[0016] Further, it continuously measuring a thickness of the wide range of the second optical scanner emitted light Rikomu measuring member by the optical path to be moved at the measured material width direction.

[0017]

EXAMPLES Example 1. Embodiment 1 of the present invention will be described below with reference to the drawings. 1 is a schematic diagram showing a configuration of a thickness measuring apparatus according to Embodiment 1 of the present invention, FIG. 2 is an operation explanatory diagram functionally showing the optical scanner in FIG. 1, and FIG. 3 is an output waveform of a photoelectric sensor in FIG. It is a waveform diagram shown. In the figure, 1
Reference numeral 2 denotes a transmitted light 2 emitted from the light source 2 and transmitted through the measured material 1.
This is an optical scanner equipped with a small mirror for optically scanning b. FIG. 2 shows a detailed structural example of the optical scanner. In the figure, 12a is an elliptical electromagnetic coil, 12b is a shaft fixed to this coil 12a,
Reference numeral 12c is a small total reflection mirror attached to the shaft 12b, and the whole is supported by a flexible, for example, coil spring 12d so as to be rotatable and swingable with respect to the shaft 12b. 13 is a driver for driving the optical scanner, such as an AC amplifier, and 2c is an optical scanner 12.
In the figure , 14 is a measuring light scanned vertically , 14 is a light shielding plate that shields half of the amplitude of the measuring light 2c, and 15 is a convex lens or a convex lens system that collects the measuring light 2c. The center O and parallel to the center a, the upper end and the convex lens 15 of the light shielding plate 14 of the optical scanner 12 on the optical axis in a state state or the reflecting surface optical scanner 12 is not swinging is not tilted <br /> Place it like this. Reference numeral 16 is a beam splitter that splits the measurement light 2d after passing through the convex lens 15 into two according to the wavelength .

The photoelectric sensors 7a and 7b and the optical filters 9a and 9b are the same as those in the prior art, and the output signals of the photoelectric sensors 7a and 7b are input to the thickness indicating device 17 and subjected to signal processing, and then the oscillator. Synchronous rectification is performed with reference to the synchronization signal from 13a to instruct calculation of the target thickness. A lock-in amplifier is a general-purpose device for the synchronous rectification device.

The operation of the optical scanner shown in FIG. 2 will be described together with the operation of the thickness measuring apparatus shown in FIG. When the DC magnetic field (N → S) alternating current coil 12a installed in the current flows, since the rectification flows in the opposite direction in the upper side and lower side of the coil 12a, the force by the Fleming's left coil 12a The upper and lower sides of the mirror work in opposite directions, and the small mirror 1 is rotated around the longitudinal direction of the shaft 12b.
2c changes the inclination with respect to the incident light. Upper and lower lateral transmitted light 2b on the figure by the operation of the optical scanner 12
The measurement light 2c vibrates back and forth in the direction . Since the light is blocked by the light blocking plate 14, the collected light that reaches the photoelectric sensors 7a and 7b is collected.
The electric signal generated by the measured light 2d has a rectangular waveform as shown in FIG. 3, and the signal of P ₁ or P ₂ is obtained in the time zone t ₁ when the measured light 2c passes through the light shielding plate 14, and the measured light 2c is The output signal becomes zero in the time period t ₂ when the light beam is directed downward and is blocked by the light shielding plate 14.

The signals shown in FIGS. 3A and 3B are photoelectric sensors 7a,
7b, and the thickness of the measured material 1 is measured by the P ₁ / P ₂ thickness indicating device 17. Instead of the optical scanner 12, it is of course possible to use a component having a simple structure similar to the structure of the optical scanner 12, such as a vibrator of a direct-write electromagnetic oscillograph,
The whole structure is simple and compact.

Example 2. In addition, here, with the configuration of the first embodiment, selection of the optimum state for the position of the convex lens 15 is performed in the second embodiment.
As described below. When the convex lens 15 or the convex lens system is installed at a position shorter than the focal position of the convex lens 15 or the convex lens system, the measurement light 2c passing through the convex lens 15 is condensed on the photoelectric sensors 7a and 7b as shown in FIG. 4A. Spread without. Similarly, in FIG. 4B, when the position a of the optical scanner is set to the focal position of the convex lens, the light passing through the convex lens does not reach the photoelectric sensor. Also, FIG.
As shown in C, when the position a of the optical scanner is between the focal positions f and 2f, the light passing through the convex lens tends to be focused, but the focusing distance becomes extremely long, which is not suitable for downsizing the optical system. Is. However, when a is located at a position twice the focal length, the light passing through the convex lens is focused at the position -2f in FIG. The arrangement of each component under this condition is the best condition for making the optical system compact. Even when there is a at a position on the left side of 2f as shown in FIG. 4-E, the light passing through the convex lens is -f.
Although the light is condensed between 2f and -2f, the optical path length becomes long as in the case of FIG. 4C, which is not suitable for making the optical system compact.

Example 3. In order to make the optical path system compact, the convex lens 15 is replaced by the first convex lens 1 as shown in FIG.
5a and the second convex lens 15b are combined, and the distance between the optical scanner 12 and the first convex lens 15a is arranged according to the focal length of the lens.
5b is arranged in contact with the first convex lens 15a, and the photoelectric sensors 7a, 7 are aligned with the focal length of the second convex lens 15b.
By arranging the tip positions b ₁ and b ₂ of b, the optical path system can be made compact. When the emitted light 2a from the light source 2 is a parallel light having a finite diameter, the output light of the first convex lens 15a is parallel to the optical axis O ₁ b _2, but its diameter is reduced as the distance from the lens increases. Therefore, if the second convex lens 15b is installed away from the first convex lens 15a, the measurement light cannot be narrowed down on the tips b ₁ and b ₂ of the photoelectric sensors 7a and 7b, and the photoelectric sensor 7a, 7b is weak even if it is weak. Sensors 7a, 7
The output signal of b is extremely small, and the accuracy of thickness measurement is greatly reduced. Therefore, by arranging the position of the second convex lens 15b in contact with the first convex lens 15a as much as possible, the measurement light is focused on the tips b ₁ and b ₂ of the photoelectric sensors 7a and 7b and is focused. It will be possible. That is, the optical path system can be made compact, and a thickness measuring device with good photoelectric detection efficiency can be obtained.

Example 4. In vertically symmetric inclination angle change of the optical scanner 12 with respect to the optical axis in the thickness measuring apparatus of the first embodiment, the slave
It is the t ₁ and t ₂ of the rectangular wave in FIG. 3 I is an ideal state. In a thickness indicating device such as a lock-in amplifier, the measured value of the thickness changes if the ratio of t ₁ and t ₂ changes to some extent, so it must be kept constant. However, the nonlinearity of the output voltage of the driver 13, the change of the neutral point of the optical scanner, the positional deviation of each component due to temperature changes, t ₁ and t ₂ of the in some cases you change. As a countermeasure in this case, the light shielding plate 1 in FIGS.
4 has a structure capable of fine adjustment in the direction of the arrow. As a result, exactly half of the measurement light whose optical path is scanned up and down in the figure by the operation of the optical scanner 12 is guided to the convex lens 15, and the ratio of t ₁ and t _{2 in} FIG. It is possible to ensure the accuracy of measurement.

Example 5. Examples 1 to 1 shown in FIGS.
3 scans the measuring light 2c only in the vertical direction in both figures.
It is done and not in the depth direction of the page. Therefore,
As shown in Fig. 6-A and the cross section is shown in Fig. 6-B.
Alternatively, a cylindrical lens 18 may be used. This place
In this case, the lens holder has a simple structure, and the overall size and weight of the lens are small and easy to manufacture and assemble.

Example 6. Further, in each of the above embodiments, the light shielding plate
14 is a convex lens, or is placed separately from the convex lens system,
As shown in FIG. 7, the front half of the lens may be coated with a light blocking coating 19 to block the measurement light 2c. In this case, by making the lens itself move in the direction of the arrow in the figure, the time width of the measuring light intended for Example 4 (t ₁ and t _{2 in} FIG. 3).
Can be adjusted. This simplifies the structure because the light shield plate can be omitted.

Example 7. In the above embodiment, the condenser lens behind the measurement light has a structure in which the lens is arranged both above and below the optical axis, but as shown in FIG. . This makes it possible to further reduce the size and weight of the structure.

Example 8. In the above respective embodiments, with respect to the transmitted light 2b of but took a method of using an optical scanner 12 inputs as a swing method of the measurement light, placing an acoustic optical element 21 as shown in FIG. 9, the transmitted light It may be used as the measurement light 2c. In FIG. 9, a signal of the high frequency oscillator 22 is amplified by an amplifier 23 and a voltage is applied to the electrode 21a, so that a compressional wave is generated in the acousto-optic element 21, and the input light 26 is diffracted depending on the degree of the compressional density. Since the degree of density is determined by the oscillation frequency of the high frequency oscillator 22,
Passing light, that is, the optical path of the measuring beam 2c Ru varied swing like can be performed by continuously changing the oscillation frequency.

Example 9. In the above embodiment, when the measurement light (input light) is oscillated, the voltage waveform applied to the optical scanner 12 is not specified, and a general sine wave is assumed to constitute the whole and the explanation has been added. , The output wave of the oscillator 13a is shown in FIG.
The rectangular wave shown in A causes the optical scanner 12 to swing.
It can be Rukoto rectangular such as shown in FIG. 10-B. this
At this time , the output signals of the photoelectric sensors 7a and 7b become good. That is, the photoelectric sensors 7a and 7b described in the fourth embodiment.
For the problem with the deviation of t ₁ and t ₂ of the output signal of
For time to pass through the vicinity of the center of the measuring beam 2c Galle lens is short, this almost eliminated the influence of the positional deviation, such as the light shielding plate 14
Bets can be, it increases the accuracy of more accurately be measured Runode <br/> thickness measuring P ₁ / P ₂ in FIG.

Example 10. In the above example, the material to be measured 1
Of, and morphism irradiation spot-like light in a certain place, and a measure of thickness, the entire light source 2, and the photoelectric detection system when measuring the different positions of the belt-like flow in which the measured material 1 It had a basic idea of the structure for moving the width direction of the measured material 1 if in the direction perpendicular to the direction of flow Re detecting the transmitted light of the light against the linear emitted light measured material 1 The average value of the thickness of can be measured. This embodiment is shown in FIG. In the figure, a linear light source 2, or a cylindrical <br/> emitted light 2a incident on the first cylindrical lens 24
And a sheet-like originating diffuser 24a in second-side triangular irradiated to the measured material 1. The this transparently light condensed by the second cylindrical lens 25, then collimated using a concave lens 26 or the like
Then, the light is incident on the optical scanner 12 or the like similar to the above-mentioned embodiment, and the thickness is measured by signal processing. Thereby, the material 1 to be measured in FIG. 11 can be irradiated with light to measure the average thickness of the region.

Example 11. In the above embodiments, or irradiated with light on one point of the measured material 1, Example 1 0 which are linearly by diverges light to have been taken a method of measuring the thickness shown in FIG. 11
Instead of the first cylindrical lens 24 which definitive in,
The second optical scanner 27 is installed as shown in FIG.
This inclination of the optical scanner may be scanned as the exit light 2a by changes sinusoidally with respect to the optical axis is a sinusoidal on the measured material 1 flowing in a direction perpendicular to the sheet of. The transmitted measurement light 2b is guided to the concave lens 26 by the second cylindrical lens 25. The second optical scanner 27, a second <br/> cylindrical lens 25, the positional relationship of the concave lens 26 in consideration of the focus of the arrangement as well as a second cylindrical lens 25 of the convex lens 15 in FIG. 1 of the first embodiment arranged Therefore, the emitted light 2a is guided to the concave lens 26 regardless of the position on the measured material 1. The configuration and operation after the concave lens are the same as in the first embodiment, and the thickness of the measured material 1 can be measured. According to this embodiment, the thickness can be measured over the entire area of the material to be measured without moving the light source and the optical path detection system.

[0031]

As it is evident from the foregoing description, the outgoing to <br/> Ru source light including a wavelength component that absorbs the wavelength to be measured material passes according to the present invention, all on the optical axis of the transmitted light Place a reflective mirror and
By changing its inclination angle, the optical path of the reflected light is periodically changed in any direction.
An optical scanner is changed to the measurement light to a predetermined position of the optical path
And a measuring light, which is installed on the table and blocks a part of the optical path.
Condensing lens that condenses the
Located at the rear, the measurement light is selectively separated by the wavelength component and
Beam splitter to irradiate and separate measurement located at the focal point.
A photoelectric sensor that converts each constant light into an electric signal, and a photoelectric sensor
Since it is composed of a thickness indicating device that calculates the thickness of the material to be measured from the output signal of the
A continuous detection signal can be obtained and the drive unit can be downsized.
There is an effect that a thickness measuring device capable of reducing vibration and long life can be obtained.

Further, since the condensing lens is composed of the first and second convex lenses which are arranged close to or in contact with each other in series, the focal positions are brought close to each other, and the thickness measuring device which enables downsizing of the device is obtained. is there.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of a thickness measuring device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram functionally showing the optical scanner in FIG.

FIG. 3 is a waveform diagram showing an output waveform of the photoelectric sensor in FIG.

FIG. 4 is an explanatory diagram of a light collecting operation according to the second embodiment of the present invention.

FIG. 5 is a schematic diagram showing a partial configuration according to a third embodiment of the present invention.

FIG. 6 is an outline view showing the shape of parts in Embodiment 5 of the present invention.

FIG. 7 is a cross-sectional view showing a light shielding means in embodiment 6 of the present invention.

FIG. 8 is a cross-sectional view showing a light blocking means in a seventh embodiment of the present invention.

FIG. 9 is a schematic diagram showing a partial configuration according to an eighth embodiment of the present invention.

FIG. 10 is a waveform diagram for explaining the operation in the ninth embodiment of the present invention.

FIG. 11 is a schematic diagram showing a partial structure of a tenth embodiment of the present invention.

FIG. 12 is a schematic diagram showing a partial configuration of an eleventh embodiment of the present invention.

FIG. 13 is a schematic diagram showing a configuration of a conventional thickness measuring device.

FIG. 14 is an explanatory diagram showing an example of a transmitted light characteristic in the thickness measuring device.

FIG. 15 is a waveform diagram showing an output waveform in a conventional thickness measuring device.

[Explanation of reference numerals] 1 material to be measured 2 light source 2a emitted light 2b transmitted light 2c measurement light ( scanning up and down in the figure ) 2d measurement light (focusing) 7 photoelectric sensor 12 optical scanner 12c total reflection mirror 14 light-shielding plate (light-shielding means) ) 15 convex lens (condensing lens) 15a first convex lens 15b second convex lens 16 beam splitter 17 thickness indicating device (arithmetic processing unit) 19 light-shielding coating 20 half-shaped lens 21 acousto-optic element 24 first cylindrical lens 25th 2 cylindrical lens 27 2nd optical scanner

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Claims (6)

[Claims] 1. A light source that transmits emitted light to a material to be measured, and a total reflection mirror in which the inclination of a reflecting surface is constantly changed with respect to incident light on the optical axis of the transmitted light, centering on the optical axis after reflection. And a wavelength conversion unit for chopping the transmitted light into measurement light, and a condensing lens, which is composed of an optical scanner for swinging the optical path in both swings and a light shielding means for shielding the lower side of the optical axis of the optical path. A beam splitter that selectively changes the optical path of the measuring light that is received and enters, and a photoelectric sensor that is arranged corresponding to the selected optical path and has different wavelength characteristics, respectively. A thickness measuring device comprising: a light receiving part for outputting an electric signal; and a thickness indicating device for inputting the both electric signals and calculating a ratio of respective amplitudes. 2. The thickness measuring device according to claim 1, wherein the condenser lens is composed of first and second convex lenses which are arranged in series close to or in contact with each other. 3. The thickness measuring apparatus according to claim 1, wherein the light blocking means is a lens having a light blocking coating on the lower side of the optical axis of the condenser lens or a half lens having the lower side cut. 4. The wavelength conversion section includes an acousto-optical element that changes the refraction degree according to the coarse density of the oscillation frequency generated inside the transmitted light to be output and outputs both by swinging the optical path in a swinging manner around the optical axis. The thickness measuring device according to claim 1, wherein the thickness measuring device comprises a light shielding unit that shields the lower side of the optical axis. 5. A first cylindrical lens for converting emitted light into diffused light between a light source and a ratio measuring material, and a second cylindrical lens close to the transmission side of the material to be measured and corresponding to the area of the diffused light. 5. The thickness measuring device according to claim 1, wherein the second condensing lens is arranged at a light output position corresponding to the second cylindrical lens, and the second condensing lens is arranged orthogonal to the optical axis. 6. A total reflection mirror having a reflection surface whose inclination is constantly changed with respect to incident light on the optical axis between the light source and the material to be measured, and the optical path of the emitted light is periodically moved in the width area of the material to be measured. Second
5. The thickness measuring apparatus according to claim 1, wherein the optical scanner and the second cylindrical lens corresponding to the optical path of the transmitted light are provided close to the transmission side of the measured material.