JPH0351706A - Thickness measuring apparatus - Google Patents

Abstract

PURPOSE:To perform highly accurate measurement of a thickness without the effect of errors in linearity of optical sensors by computing the thickness of a body to be measured based on the amount of minute displacement of the body to be measured and the amount of movement in a distance between the optical sensors. CONSTITUTION:When the thickness of a body to be measured 10 is measured, optical sensors 1 and 2 are moved with moving mechanisms 15 and 16. The body to be measured 10 is arranged between the sensors 1 and 2. The amounts of the displacements of the sensors 1 and 2 are made to be approximately zero. At this time, the moving amounts of the sensors 1 and 2 from the time when a reference body to be measured 13 is measured to the time when the body to be measured 10 is measured is operated in a first operating part 9a. The moving amounts are detected with moving amount detectors 17 and 18. The thickness of the body to be measured 10 is operated in a second operating part 9b based on the amounts of the displacements and the thickness of the body to be measured 13. When the body to be measured 13 is measured beforehand and the amounts of the displacements from the sensors 1 and 1 at this time are made to be approximately zero, the body to be measured 10 can be measured highly accurately.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a thickness measuring device that non-contactly measures the thickness (plate thickness, etc.) of an object to be measured using an optical sensor. The present invention relates to a thickness measuring device that can suppress measurement errors due to linearity errors as much as possible.

[Prior Art] As a conventional technology of this kind, for example, there is a laser type displacement/thickness meter described in "How to Use Process Sensors in Practical Examples" published by Kogyo Gijutsu Sha, 1981, Measurement, Separate Volume (280 pages). This will be explained with reference to FIG. 4 and FIGS. 5(a) and (b).

Fig. 4 is a schematic configuration diagram showing a conventional device, Fig. 5(a), (
b) is an explanatory diagram showing the principle of thickness measurement, and as shown in these diagrams, the conventional device uses optical sensors 1 and 2 facing each other, and Display unit connected to optical sensors 1 and 2 (
1st calculation unit) 5°6 and each display unit 5, 6
The double-sided arithmetic unit (second arithmetic unit) 9 is connected to the two-sided arithmetic unit (second arithmetic unit) 9 via wiring 7.8.

Next, the operation will be explained. Between optical sensors 1 and 2, a fourth
As shown in the figure, when the object to be measured 10 whose thickness is to be measured is located, the laser beams 1 and 2 are emitted from the optical sensors 1 and 2 respectively.
1.12 is irradiated onto each surface of the object to be measured 10, and the reflected light is detected by the optical sensors 1 and 2.

At this time, as shown in FIG. 5(a), a reference measured object 13 having a known thickness d is placed between the optical sensors 1 and 2, and first, the reflected light on the reference measured object 13 is A beam spot (reference point) is detected by the optical sensor 1.degree. 2, and an offset value based on the beam spot is determined in advance.

Next, as shown in FIG. 5(b), the object to be measured 10 is placed between the optical sensors 1 and 2, and the laser beam 11 is emitted in the same manner as described above.
．． 12 is irradiated onto the object to be measured 10 from the optical sensors 1 and 2, the reflected light is detected, and the thickness D of the object to be measured 10 is measured from the amount of displacement between the detection point and the reference point.

To explain more specifically, the optical sensors 1 and 2 emit reflected light obtained by irradiating the laser beams 11 and 12 from the optical sensors 1 and 2.
The detection point in moves from the reference point according to the thickness of the object to be measured 10 and the arrangement position. The amount of movement is converted into an electrical signal, and a microprocessor (built in the display unit) calculates the amount of movement to obtain the amount of displacement Q from each surface of the reference object to be measured 13 to each surface of the object to be measured 10. a.Qob
is required.

The displacement amounts 0°a, Q, b obtained in this way are displayed on the display units 5, 6 connected to the respective sensors 1, 2.
Each value is displayed above.

It is input to the double-sided calculator 9 and is processed based on the following calculation formula to calculate the thickness D of the object to be measured 10.
The measurement of the thickness D of 0 is completed.

D=d+Q, a+Q, b In the above equation, D is the thickness of the object to be measured 10, d is the thickness of the reference object to be measured 13, ΩI, a is the amount of displacement detected by the sensor 1, and QI, b are This is the amount of displacement detected by the sensor 2.

[Problems to be Solved by the Invention] However, as the characteristics of the optical sensors 1 and 2, the optical sensors 1 and 2 have different characteristics.
Even within the measurement range of 2, the relationship between the displacement amount and the outputs of the optical sensors 1 and 2 ceases to be a straight line as the distance from the reference origin of the optical sensor 1°2 increases.

The so-called linearity error increases (see the dotted line in Figure 6), which leads to a measurement error in the amount of displacement when measuring the thickness.
There is a problem in that this results in an error in the thickness of the object to be measured 10.

This invention was made to solve the above-mentioned problems, and the purpose is to obtain a thickness measuring device that can measure thickness with high precision without being affected by linearity errors of optical sensors. do.

[Means for Solving the Problems] A thickness measuring device according to the present invention includes a pair of devices arranged opposite to each other so as to irradiate both surfaces of a measured object with laser light and detect the incident position of the reflected light. a first calculation unit connected to each of the optical sensors to calculate the amount of displacement between the incident position of the reflected light detected by each of the optical sensors and a reference point of a reference measured object having a known thickness; and a second calculating section capable of calculating the thickness of the object to be measured.

A moving mechanism that moves each of the above-mentioned optical sensors in the normal direction of each surface of the above-mentioned object to be measured, and a movement amount detector that detects the amount of movement of each of the above-mentioned sensors by each of the above-mentioned moving mechanisms. Attached to the optical sensor, when measuring the thickness of the object to be measured, each of the above-mentioned light beams is moved so that the distance between each of the optical sensors and each surface of the object to be measured becomes approximately the reference origin using each of the moving mechanisms described above. The sensor is positioned, and at this time, the amount of movement of each optical sensor from the time of measurement of the reference object to the time of measurement of the object detected by each of the movement amount detectors described above, and the displacement calculated by the first calculation section. The thickness of the object to be measured is calculated by the second calculation section based on the amount and the thickness of the reference object to be measured.

[Function] In the thickness measuring device of the present invention, first, when measuring the thickness of a reference object to be measured, the distances between a pair of optical sensors arranged opposite to each other and each surface of the reference object to be measured are approximately the same. The thickness of the reference object to be measured is measured and stored based on the distance between the optical sensors and the amount of displacement from each optical sensor at that time. When measuring the thickness of an unknown object to be measured, set the distance between each optical sensor and each surface of the object to be approximately the reference origin of the optical sensor.
After each optical sensor is moved by the moving mechanism, the amount of movement of each optical sensor from the time of measurement of the reference object detected by the movement amount detector to the time of measurement of the object to be measured is calculated by the first calculation section. amount of displacement.

The thickness of the object to be measured is calculated and measured by the second calculation section based on the thickness of the reference object to be measured.

In other words, when measuring the thickness of an object to be measured, the thickness of the object is measured based on the minute displacement of the object near the reference origin of a pair of optical sensors arranged opposite to each other and the amount of distance movement between each optical sensor. Since the thickness of the object to be measured is calculated, the linearity error that each optical sensor has in its characteristic 1 will be corrected.

[Embodiments of the invention] An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 1.2 denotes a pair of upper and lower optical sensors that irradiate both surfaces of the object to be measured 10 with laser light and detect the incident position of the reflected light, as shown in FIG. 2(a).

As shown in (b), the optical sensors 1 and 2 are arranged at the tip of the U-shaped support mechanism 14 so as to face each other from above and below. Reference numeral 9 denotes a computing unit having a first computing unit 9a and a second computing unit 9b, and the first computing unit 9a is connected to the optical sensors 1 and 2 via wiring 19. The amount of displacement between the incident position of the reflected light detected by each of the optical sensors 1.degree. 2 and the reference point of the reference measured object 10 of known thickness is calculated. Further, the second calculation unit 9b connects a vertical movement amount detector 17°18, which will be described later, via the arrangement i21°22.
The thickness of the object to be measured 10 can be calculated using the calculation procedure described later.

Further, 15.16 is a vertical movement mechanism that moves the optical sensors 1 and 2 in the vertical direction (in the normal direction of each surface of the object to be measured 10), and 17.18 is a vertical movement mechanism 1, respectively.
5.16 with a vertical movement amount detector that detects the amount of movement of each optical sensor 1°2.

The moving mechanism 15.16 and the moving amount detector 17°18 are
As shown in FIGS. 3(a) and 3(b), they are attached near the optical sensors 1 and 2, respectively.

When measuring the thickness, as shown in FIGS. 2(a) and 2(b), a
A strip-shaped reference measured object 13 or measured object 10 is arranged.

With the above configuration, when measuring thickness, first
a) As shown in FIG. 3(a), the optical sensors 1 and 2 irradiate each surface of the reference object 13 with laser light and detect the reflected light, and the displacement from the optical sensors 1 and 2 is detected. The moving mechanism 15, Each optical sensor 1 at 16
, 2 to detect the amount of displacement from the optical sensors 1 and 2 and the amount of vertical movement of the optical sensor 1.
8) is used to determine the offset value.

Next, as shown in FIGS. 2(b) and 3(b), in order to measure the thickness of the measured object 10 of unknown thickness, the measured object l is
O is placed between the optical sensors 1 and 2, so that the amount of displacement from each optical sensor 1 and 2 is almost zero (that is, between each optical sensor 1 and 2 and each surface of the object to be measured 1o) (so that the distance is approximately the reference origin of optical sensors 1 and 2), and each optical sensor 1
, 2 are moved by moving mechanisms 15 and 16. and,
At this time, each optical sensor 1.2 detected by the movement amount detector 17.18 from the time of measuring the reference object to be measured to the time of measuring the object to be measured.
The thickness D□ of the object to be measured 1o is calculated and measured by the second calculation section 9b based on the amount of movement of , the amount of displacement calculated by the first calculation section 9a, and the thickness Dll of the reference object 1o. Ru.

That is, based on the known thickness of the reference object to be measured 13, the optical sensor 1 is adjusted such that the amount of displacement from each optical sensor 1, 2 is approximately zero.
, 2 are moved and placed, respectively, as YU, ,Y
L,, optical sensors 1, 2 measured by optical sensors 1, 2
and each surface of the reference object to be measured 10, respectively SU
,,SL,, the thickness of the object 10 to be measured is Dl, the object 10 to be measured is
The positions of the optical sensors 1 and 2 when they are moved and arranged so that the amount of displacement from the optical sensors 1 and 2 is almost zero are measured by the optical sensors 1 and 2, YU, YL, respectively. If the distances between the optical sensors 1 and 2 and each surface of the object to be measured 10 are SU□ and SL, the thickness of the object to be measured 10 is calculated by the following formula in the second calculation section 9b. .

D engineering=D, +((YUL-YU,)+(YL□-YL,
))-((SU,-SU,)+(SL,-SL
, )) Here, (YUneeY UJt (Y Lx
Y Lo) corresponds to the amount by which the optical sensors 1 and 2 moved from the time of measurement of the reference object 13 to the time of measurement of the object 10, and is detected by the vertical movement amount detector 17°18. It is something that Also, (SU.

-S U, ) and (S L, -5Lll) are the reference values of the reference object 13 whose thickness and incident position of the reflected light detected by the optical sensors 1 and 2 on the object 10 are known, respectively. This corresponds to the amount of displacement with respect to the point, and is calculated by the first calculation unit 9a.

As described above, according to the apparatus of this embodiment, when measuring the thickness of the object to be measured 10, the minute displacement amount (first calculation) of the object to be measured near the reference origin of the pair of upper and lower optical sensors 1. Part 9
Based on the amount of movement of the distance between each optical sensor 1 and 2 (output from the movement amount detector 17 and 18),
Since the thickness D□ of the object to be measured 10 is calculated by the second calculation unit 9b, the linearity error (see FIG. 6) that each optical sensor 1, 2 has in its characteristic 1 is corrected, and therefore .

It becomes possible to measure the thickness of the object to be measured 10 extremely accurately.

[Effects of the Invention] As described above, according to the present invention, when measuring the thickness of an object to be measured, the amount of minute displacement of the object to be measured in the vicinity of the reference origin of a pair of optical sensors arranged opposite to each other, and each The structure is configured so that the thickness of the object to be measured can be calculated based on the amount of distance movement between the optical sensors, so it is possible to achieve extremely high accuracy without being affected by the linearity error that each optical sensor inherently has. This has the effect of providing a device that can measure the thickness of an object to be measured.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram showing a thickness measuring device according to an embodiment of the present invention, and FIGS. 2(a) and (b) show the above-mentioned embodiment when measuring the thickness of a reference object and an object to be measured, respectively. 3(a) and 3(b) are a side view and a side view showing the main parts of the apparatus of the above embodiment when measuring the thickness of a reference object and an object to be measured, respectively Figure 4 is a schematic configuration diagram showing the conventional device, Figures 5 (a) and (b) are explanatory diagrams showing the principle of thickness measurement, respectively, and Figure 6 is a graph to explain the linearity error of the optical sensor. It is. In the figure, 1, 2 - optical sensor, 9a - first calculation section,
9b-second calculation unit, 10-object to be measured, 13-reference object to be measured, 15.16-vertical movement mechanism, 17.18-vertical movement amount detector. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] A pair of optical sensors are placed opposite each other to irradiate both sides of the object with laser beams and detect the incident position of the reflected light, and the incident position and thickness of the reflected light detected by each of these optical sensors. a first calculation section connected to each of the optical sensors to calculate the amount of displacement with respect to a reference point of the known reference object; and a second calculation section capable of calculating the thickness of the object to be measured. The thickness measuring device of Naete includes a moving mechanism for moving each of the optical sensors in the normal direction of each surface of the object to be measured, and detecting the amount of movement of each of the sensors by each of the moving mechanisms. A movement amount detector is attached to each of the above-mentioned optical sensors, and when measuring the thickness of the above-mentioned object to be measured, the distance between each of the above-mentioned optical sensors and each surface of the above-mentioned object to be measured is approximately equal to Each of the optical sensors described above is positioned to serve as a reference origin, and at this time, the amount of movement of each of the optical sensors detected by each of the movement amount detectors from the time of measurement of the reference object to the time of measurement of the object to be measured, A thickness measuring device characterized in that the second calculation section calculates the thickness of the object to be measured based on the displacement amount calculated by the first calculation section and the thickness of the reference object to be measured.