JPH085322A - Manufacture of displacement-amount measuring appartus and its density changing filter - Google Patents

Abstract

PURPOSE:To obtain a density changing filter and a displacement-amount measuring apparatus, wherein conversion of the displacement amount and the amount of transmission is simple, by photographing a dot pattern, which is formed by the specified method, and using the film as a filter. CONSTITUTION:The pattern of dots 9 is photographed, and the film is used as a filter. The dot pattern is dotted at the intersecting points of measures. When a density is linearly changed in the direction of (x), the interval of the measures is changed in proportion to the square root of (x). The dot pattern is dotted at the vertexes of the approximately square shape, whose length of the side is changed by the value of (x). Four points belong to one square, but at the same time, the respective point belongs to four squares. Therefore, one point belongs to one square. When such a dot pattern is photographed, black and white are inverted, and the part of the dot point becomes white and the transmitting part, and the part other than the transmitting part becomes black and the light screening part. Since the area of the square is constant, the transmittance of the film is inversely proportional to the area of the square.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a displacement amount measuring device and a method of manufacturing a density change filter for converting the displacement amount into a light transmission amount.

[0002]

2. Description of the Related Art As a method for measuring the amount of displacement of an object, an elongated filter whose density changes in the longitudinal direction is used.
The amount of displacement can be known from the change in the intensity of the light passing therethrough.

In particular, if the change in density with respect to the length direction is linear, it becomes extremely easy to convert the change in the amount of transmitted light into the amount of displacement.

Since this method uses light, it is not affected by electromagnetic noise and has the advantage that it can perform measurement without problems even if the object to be measured and the measuring instrument (measuring person) are at different potentials. Therefore, it is effective for measuring the amount of displacement of a moving part of a high voltage device or a place where a large electromagnetic noise is generated.

[0005]

A filter whose concentration changes in the longitudinal direction is usually formed by depositing a chrome film or the like on the surface of glass while changing the thickness.

Such a filter is expensive and easily cracked by impact. It is also possible to take a picture of such a filter and use the film as a filter, but in the case of a photographic film, since the exposure amount and the density do not always have a constant relationship, the conversion of the displacement amount and the transmission amount becomes complicated. There is a problem.

The present invention has been made in view of the above problems, and an object thereof is to take a photograph of a dot pattern and use the film as a filter to easily convert a displacement amount and a transmission amount. And to provide a displacement amount measuring device.

[0008]

In order to achieve the above object, the present invention irradiates a filter for converting a displacement amount of a moving object into a transmission amount of light with light, and controls a light amount emitted through the filter. In the device for measuring the displacement amount of the moving object, as the filter, dots having a predetermined size are plotted at intersections of squares to form a dot pattern, and the dot pattern is used as a film. It is characterized by having done.

Further, according to the present invention, dots having a predetermined size are plotted at the intersections of the squares, and a dot pattern in which the intervals of the squares are changed in a predetermined direction is obtained, and the density of the dot pattern is set to the distance. Change according to a function.

[0010]

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

FIG. 1 shows a displacement amount measuring apparatus according to an embodiment of the present invention. Reference numeral 1 is a light emitting element driving power source, 2 is a light emitting circuit, 3a and 3b are optical fibers, 4 is a density changing filter, 5 is a light receiving circuit, Reference numeral 6 is an amplifier, 7 is a measuring unit composed of a voltmeter, an oscilloscope, a digital memory or the like, and 8 is a moving object.

In the measuring device of FIG. 1, the light emitting circuit 2 is driven by the power source 1 to emit light. The light from the light emitting circuit 2 is applied to the filter 4 through the optical fiber 3a.
The filter 4 converts the displacement amount of the moving object 8 into a light transmission amount. The light from the filter 4 is guided to the light receiving circuit 5 through the optical fiber 3b. The light receiving circuit 5 converts the optical signal into an electric signal, amplifies the electric signal by the amplifier 6, and then inputs the electric signal to the measuring unit 7. The measuring unit 7 measures the displacement amount of the moving object 8 based on the electric signal.

In order to obtain a filter whose density varies in the lengthwise direction, a pattern of dots 9 is photographed and its film 10 is used as a filter, as shown in FIGS. This dot pattern is formed by striking at the intersections of squares. If the density is changed linearly in the x direction, the interval between squares is changed in proportion to the reciprocal of the square root of x.

The dot pattern shown in the embodiment is spotted on the apex of a substantially square (correctly a large diameter, hereinafter referred to as a square) whose side length changes depending on the value of x. Here, D is the side length (dot interval) as a function of x.
If (x) and a are arbitrary coefficients, D (x) = a / √ (x) (1) Therefore, the area S (x) of the square is S (x) = D (x) ² = a ² / (√ (x)) ² = b / x (2) b = a ² (3) That is, the area of the square is proportional to 1 / x.

By the way, four points belong to one square, but at the same time, each point belongs to four squares. Therefore, one point belongs to one square. become.

When such a dot pattern is photographed using a film having a high resolution and a high contrast, black and white are reversed and the spotted portion is white as shown in FIG.
2 (light is transmitted), and the other portions are black and serve as the light shielding portion 11 (light is blocked).

Since the area of the spotted portion is constant,
The transmittance T (x) of the film (ratio of the light transmitting portion to the light blocking portion) is inversely proportional to the square area. Therefore, T (x) = c / s (x) = c / b · x) = d · x (4) is obtained. Here, c and d are constant values.

That is, the amount of transmitted light is proportional to x.

By applying the filter thus manufactured to the method shown in FIG. 1, the displacement amount can be linearly converted into the transmitted light amount.

Here, it is assumed that the measuring light has a sufficient spread with respect to the interval between the dots. This averages the effect of the individual dots on the measurement.

According to the present invention, the following embodiments can be obtained.

(1) Plot dots having a constant size at the intersections of the squares to obtain a dot pattern.

(2) The distance between the squares is changed according to the distance in the x-axis direction.

(3) The dot pattern is photographed using a film having high resolution and high contrast.

(4) The photographed film is used as a filter for converting the amount of displacement into the amount of transmitted light.

(5) When it is desired to make the relationship between the displacement amount and the transmitted light amount linear, the interval D (x) is D (x) = a / √ (x) a is an arbitrary coefficient.

(6) The relationship between the amount of displacement and the amount of transmitted light is not limited to linear. For example, if D (x) = a + x, the area of a square formed by dots S (x) = b / x ² transmittance T (x) = c / S (x) c / b · x 2 = d · x 2 , and the light passing through is proportional to the square of the displacement.

If D (x) = a / √ (exp (x)) (5), then S (x) = b / exp (x) (6) T (x) = c / S (X) = d · exp (x) (7), and the transmission amount changes exponentially with respect to the displacement.

More generally, if D (x) = a / √ (f (x)) (8), then the transmission amount becomes T (x) = d · f (x) (9) It is possible to easily obtain a filter whose density changes according to a function.

[0030]

As described above, the present invention irradiates a filter for converting a displacement amount of a moving object into a light transmission amount, and measures the amount of light emitted through the filter to measure the moving object. In the device for measuring the amount of displacement, as the filter, dots having a predetermined size are plotted at the intersections of the squares to form a dot pattern, and the dot pattern is constructed using a film, so the displacement amount is moved. A high-performance displacement amount measuring device can be obtained by easily converting the displacement amount of an object and the light transmission amount.

Further, according to the present invention, dots having a predetermined size are plotted at the intersections of the squares, and a dot pattern in which the intervals between the squares are changed in the predetermined direction is obtained, and the density of the dot pattern is determined as described above. Since it is changed according to the function of distance, a high-performance density change filter whose density changes according to an arbitrary function can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram of a displacement amount measuring device according to an embodiment of the present invention.

FIG. 2 is a dot pattern diagram.

FIG. 3 is a configuration diagram of a density change filter according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Power supply 2 ... Light emitting circuit 3a, 3b ... Optical fiber 4 ... Density change filter 5 ... Light receiving circuit 7 ... Measuring part 9 ... Dot 10 ... Film

Claims (2)

[Claims] 1. A device for irradiating light to a filter for converting a displacement amount of a moving object into a light transmission amount, and measuring the amount of light emitted through the filter to measure the displacement amount of the moving object, wherein the filter is A displacement amount measuring device characterized in that dots having a predetermined size are plotted at the intersections of squares to form a dot pattern, and the dot pattern is used to form a film. 2. A dot pattern in which dots having a predetermined size are plotted at the intersections of squares and the distance between the squares is changed in a predetermined direction to obtain a dot pattern, and the density of the dot pattern is changed according to the function of the distance. A method of manufacturing a density change filter, which is characterized by the above.