JPH0670566B2 - Displacement measuring device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a displacement measuring device that optically measures the displacement of a measurement target with high accuracy over a wide measurement range.

(Prior Art) Measuring the displacement of a measurement target such as a roll, a thin plate, or a pipe is important for shape measurement (profile measurement), dimension measurement, or position detection.

As a device for measuring this kind of displacement, a laser triangulation type displacement meter has been conventionally used and is widely used. This is to irradiate the target surface with a small laser beam, to focus the reflected light from the oblique direction with the light receiving lens to form an image on the optical position detection element, and to electrically change the optical image position accompanying the displacement of the target. It is converted into a signal. However, in this displacement measuring device, the resolution and accuracy of the optical position detection element are limited, and the diameter of the laser beam on the target surface changes significantly when the measurement target is displaced, etc. It is extremely difficult to obtain.

Therefore, in such displacement measurement, measures are taken to enhance the measurement accuracy. For example, laser light is irradiated in parallel to the displacement direction of the measurement target so that the laser light is irradiated on the measurement target surface in a narrowed state. There is a device (Japanese Patent Publication No. 59-762). According to this, the measurement point becomes clear and the accuracy is improved, but due to the change in the distance between the illumination side condenser lens and the measurement target caused by the displacement of the measurement target,
It cannot be denied that the diameter of the laser beam on the surface to be measured changes.

(Problems to be Solved by the Invention) By the way, when a profile is measured by rotating or running an object to be measured, such as a pipe or a roll,
Displacement must be measured without being affected by vertical movement or vibration that does not depend on the profile of the measurement target itself.

Generally, the vertical movement and the vibration are much larger than the change of the profile, so that a device having a wide measurement range is indispensable. For example, when the displacement of the pipe is 2 mm and the displacement measurement of the pipe is required with an accuracy of 1/1000 mm, the resolution and accuracy of the optical position detection element are limited, and the measurement limit is smaller than the vibration. Therefore, it becomes impossible to measure. Therefore, in order to perform such a measurement, it is inevitable to go offline, and it takes a long time for the measurement.

Further, in order to measure the surface roughness of a roll or a thin plate such as a strip, it is necessary to measure the degree of fine irregularities on the surface, for example, of the order of μm. In such a case, it is necessary to measure the displacement based on the fine irregularities on the surface with high accuracy, but there is no one that can measure this using a light beam.

(Object of the Invention) The present invention provides an optical displacement measuring device having a high precision and a wide measuring range, such as shape measurement, surface roughness measurement, dimension measurement or position detection of a measuring object such as a roll, a pipe or a strip. It is an object of the present invention to provide a displacement detection device that can perform rotation or running.

(Means for Solving the Problems) In order to achieve the above object, in the present invention, a measurement object is irradiated with a light beam through a focusing lens, and the reflected beam is received from an optical axis direction different from that of the light source and displaced. In a device for measuring: fixed tilt mirror and moving tilt pair mirror provided between the optical axis from the focusing lens to the object to be measured and the optical axis to the light receiving lens of the reflected beam, the image forming position of the light receiving lens receiving the reflected beam Of the optical position detecting element provided in the above, the position signal processing device for outputting the position signal based on the signal from the optical position detecting element, the device for inputting the position signal and controlling the moving amount of the moving tilt pair mirror, the moving tilt pair mirror A movement amount detection device that detects the movement amount and outputs a movement amount detection signal, and a displacement calculation device that inputs the movement amount detection signal and the position signal and outputs the displacement of the measurement target.

An embodiment of the present invention will be described in detail below with reference to the drawings.

(Embodiment) In FIG. 1, 1 is a semiconductor laser as a light source, 2 is a modulation signal generator, 3 is a laser beam, and 4 is a focusing lens. The focusing lens 4 serves to irradiate the measurement target 5 with the laser beam 3 as a thin beam. Reference numeral 6 denotes a fixed tilt mirror, and in the present embodiment, two mirrors 6a and 6b are joined to each other at a predetermined angle with their reflecting surfaces facing outward, and are installed on the optical axis between the focusing lens 4 and the measurement object 5. . The laser light 3 from the focusing lens 4 is reflected by the upper mirror 6a of the fixed tilt mirror 6,
It is incident on the moving tilt pair mirror 7. In this embodiment, the reflecting surfaces of the two mirrors 7a and 7b are joined to each other at a predetermined angle to form a moving tilt pair mirror 7, and each reflecting surface and each reflecting surface of the tilting mirror 6 are opposed to each other. There is. This movable tilt pair mirror 7 is movable in the direction of arrow A, and is between the focusing lens 4 and the measurement object 5 and between the measurement object 5 and the light receiving lens 15 due to the displacement of the measurement object 5 from the measurement initial position or the measurement reference position.
Absorbs changes in optical path length between That is, as will be described later,
In this embodiment, a fixed tilt mirror 6 and a moving tilt pair mirror 7 are provided to make the optical path length between the focusing lens 4, the measuring object 5 and the light receiving lens 15 constant regardless of the displacement of the measuring object 5. There is a big feature of.

By the way, the laser beam 3 reflected from the upper mirror 6a of the fixed tilt mirror 6 to the upper mirror 7a of the moving tilt pair mirror 7
Are further reflected at the reflection point 8 of the upper mirror 7a, the reflection point 9 of the lower mirror 7b, and the reflection point 10 of the lower mirror 6b of the fixed tilt mirror 6, and irradiate the measurement target 5 as minute spot light. .

In the measurement target 5, a part of the scattered laser light is a reflection point 11 of the lower mirror 6b of the fixed tilt mirror 6, a reflection point 12 of the lower mirror 7b of the moving tilt pair mirror 7, a reflection point 13 of the upper mirror 7a,
The light is reflected at the reflection points 14 of the upper mirror 6a of the fixed tilt mirror 6 and guided to the light receiving lens 15.

Reference numeral 16 is an optical position detecting element.

17 is the position of the received light spot on the optical position detecting element 16 when the measuring object 5 is at the reference position shown by the solid line in FIG. 1, and 18 is the measuring object 5 displaced to the position shown by the broken line in FIG. It is the position of the received light point at the time.

Reference numeral 20 denotes a moving device including a linear motor, which reciprocally drives the moving tilt pair mirror 7 in the arrow A direction.

Reference numeral 21 denotes a movement amount detection device, which detects the movement amount of the movement inclination of the mirror 7.

A position signal processing device 22 outputs a position signal corresponding to the light spot position on the optical position detecting element 16 from the output signal from the optical position detecting element 16 and the timing signal of the modulation signal generator 2.

23 is a movement control device, which receives a position signal from the position signal processing device 22 and outputs a movement command signal to the movement device 20 (the movement amount signal from the movement amount detection device 21 is further input to the movement control device 23). You may issue a move command).

A displacement calculator 24 calculates and outputs the displacement amount of the measuring object 5 from the position signal from the position signal processing device 22 and the movement amount signal from the movement amount detection device 21.

Next, the operation of the embodiment apparatus will be described. After passing through the focusing lens 4, the laser light 3 of the semiconductor laser 1 is reflected by the fixed tilt mirror 6 and the moving tilt pair mirror 7, and is irradiated onto the surface of the measurement target 5 as a minute spot light. At this time, the state of reflection by the fixed tilt mirror 6 and the moving tilt pair mirror 7 will be described in detail with reference to FIGS. 2 and 1.

The laser light 3 is bent at a right angle by the fixed tilt mirror 6, is then returned by the moving tilt pair mirror 7, is bent again at a right angle by the fixed tilt mirror 6, and is irradiated onto the surface of the measurement target 5. A part of the laser light diffusely reflected by the measurement target 5 is reflected by the fixed tilt mirror 6 and the moving tilt pair mirror 7, and the light position detecting element placed at the image forming position by the light receiving lens 15.
An image is formed on the 16 as a small spot light. In this case, when the measurement target 5 and the movable tilt pair mirror 7 are at the reference position shown by the solid line in FIG. 2, the minute spot light on the optical position detecting element 16 is incident on the light receiving point 17 at the center of the optical position detecting element 16. Adjust it to come. Now, when the measurement object 5 is displaced from the reference position to the position shown by the broken line in FIG. 2, the irradiation position of the spot light on the optical position detection element 16 is displaced from the light receiving point 17 to the light receiving point 18 and its light diameter is also large. Become. The position signal of this displacement approaches the center of the optical position detection element 16, and the movement control device 23 urges the movement device 20 to drive the moving tilt pair 7 mirror in order to reduce the light diameter and improve the measurement accuracy. . When the moving tilt-pair mirror 7 is moved in this way, the moving tilt-pair mirror 7 moves to, for example, the position of the broken line in FIG. 2, and the optical paths of the laser light and the light receiving system are changed from the reflection points 25, 26, 27, 28. It is displaced to the reflection points 25, 29, 30, 28 and absorbs the displacement of the measurement target 5 from the reference position to keep the optical path length seen from the reflection point 25 constant.

Therefore, the focus of the laser light and the focus position of the light receiving system do not change and the optical detection accuracy does not decrease. Therefore, the movement amount of the mirror 7 is detected by the movement amount detection device 21, and the displacement amount of the measurement target 5 is detected. Can be measured with high accuracy. At this time, the displacement measuring range of the measuring object 5 is not limited to the detecting range of the optical position detecting element 16, and is twice the moving range of the moving tilt-to-mirror 7 and the measuring range is greatly expanded. Become.
Further, it is not necessary to move the movable tilt pair mirror 7 until the light receiving position on the light position detecting element 16 reaches the center position 17, and it is sufficient if the spot light position is within the detection range of the light position detecting element 16, The displacement calculation device 24 can calculate the displacement signal 31 of the measurement object from the position signal and the movement amount signal of the movement inclination pair mirror 7.

Further, in the above-described embodiment, the fixed tilt mirror 6 and the moving tilt pair mirror 7 are configured by combining two mirrors at an acute angle, but the invention is not limited to this, and the fixed tilt mirror 6 is placed on the upper side as shown in FIG. The same effect can be obtained by dividing the mirror 6a into the lower mirror 6b and the moving tilt pair mirror 7 into the upper mirror 7a and the lower mirror 7b.

Further, as shown in FIG. 4, the fixed tilt mirror 6 may be only the upper mirror 6a. In short, the combined reflection of the fixed tilt mirror 6 and the moving tilt pair mirror 7 absorbs the change in the optical path length due to the displacement of the measurement object 5. However, the combination may be fixed.

Further, not limited to the semiconductor laser used in the embodiment, there are modifications that use other light sources such as LEDs and modifications that use a known drive mechanism for the moving device, but description thereof is omitted here.

It is also possible to modulate the light source to remove the influence of ambient light, or to measure an object that is displaced at high speed by pulse modulation.

(Advantages of the Invention) With the above-described configuration and operation, according to the present invention, it is possible to measure the displacement of the measuring object with high accuracy and in a wide range. For example, profile measurement of rolls, pipes, strips, or screw portions is possible.・ Surface roughness measurement and plate thickness measurement of thin materials such as strips can be done online.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention. FIG. 2 is an explanatory diagram for explaining the operation of the first embodiment of the present invention. FIG. 3 is a side view showing the configurations of a fixed tilt mirror and a moving tilt pair mirror in the second embodiment of the present invention. FIG. 4 is a side view showing a configuration diagram of a fixed tilt mirror and a moving tilt pair mirror in the third embodiment of the present invention. 1: Semiconductor laser, 2: Modulation signal generator 3: Laser light (light beam) 4: Focusing lens, 5: Target of measurement 6: Fixed tilt mirror, 7: Moving tilt pair mirror 15: Light receiving lens 16: Detection element (light Position detecting element) 20: Moving device, 21: Moving amount detecting device 22: Position signal processing device 23: Moving amount control device (device for controlling moving amount) 24: Displacement calculation device, 31: Displacement signal

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Hidetaka Konan Hidetaka Konan 1-1-1 Edamitsu, Yawatahigashi, Kitakyushu, Kitakyushu, Fukuoka Inside the Yawata Works (72), Nippon Steel Corporation (72) Takanori Yamamoto, Yawatahigashi, Kitakyushu, Fukuoka 1-1-1 Kueda Mitsuda 1-1-1 Inside Nippon Steel Co., Ltd. Yawata Works (56) References JP-A-60-95306 (JP, A) JP-A-60-95307 (JP, A) JP-A-57-93208 (JP, A)

Claims (1)

[Claims] 1. A device for irradiating a measurement object with a light beam through a focusing lens, and receiving the reflected beam from an optical axis direction different from that of a light source to measure displacement: an optical axis and reflection from the focusing lens to the measurement object. Fixed tilt mirror and moving tilt pair mirror provided between the optical axes of the beam receiving lens; optical position detecting element provided at the image forming position of the receiving lens receiving the reflected beam; based on a signal from the optical position detecting element Position signal processing device for inputting a position signal to control the moving amount of the moving tilt-to-mirror; moving amount detecting device for detecting the moving amount of the moving tilt-to-mirror and outputting a moving amount detection signal And a displacement calculation device that inputs a movement amount detection signal and a position signal and outputs the displacement of the measurement target;