JPS5948322B2 - Moving surface end detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for detecting the end of a moving surface, and more particularly to a device for detecting the end of a membrane member or the like moving on a stationary surface or a surface moving at very low speed.

For example, in a recording device using a metal tape, it is difficult to recognize the position of the edge of the tape because the movement of the metal tape on the metal surface has a reflectance that is not much different from that of the underlying metal surface. It is difficult.

Conventionally, no technique suitable for solving the above problem has been found. The present invention provides an end detection device for a moving surface to improve the above-mentioned conventional problems.

The end detection device of a moving surface according to the present invention includes a continuous output laser, an optical system that converges the laser light near the boundary between two members having a speed difference and scans it continuously or stepwise, the laser, The device is characterized in that it includes a light receiving system that receives reflected and scattered light of the laser beam, and a spectrum analyzer that measures the frequency spectrum of the detected electrical signal, and detects the boundary position between the two members based on a change in the spectrum. Also,
The optical system according to claim 2 of the present invention is characterized by comprising an ultrasonic modulation element for deflecting laser light.

Next, one embodiment of the present invention will be explained in detail with reference to the drawings.

In FIG. 1, 1 is a stationary surface, and 2 is a moving surface that moves on the stationary surface at a speed V in the direction of the dashed arrow, and the edge 2a of this moving surface 2 is a boundary site to be measured. Next, 3 is a laser beam, which is converged to have an appropriate spot diameter on the stationary surface 1 and the moving surface 2, and travels on the two surfaces 1 and 2 as a trajectory 4 on a plane. The edge 2a of the moving surface is scanned stepwise in the perpendicular direction. In Figure 1, 1
1 is a laser beam oscillation section, and 12 is a laser beam scanning section. In addition, in the optical system for scanning the laser beam, it is preferable to use an ultrasonic modulation element to deflect the laser beam. Reflected light 5 generated by scanning perpendicular to the edge 2a of the moving surface is detected by a light receiving section of a certain size provided above the surfaces 1 and 2. In addition, the reflected light from the surfaces 1 and 2 has a spatial distribution of intensity called speckle, and while the reflected light from the stationary surface 1 is temporally stationary, the moving surface 2 The reflected light changes over time. At this time, when the signal received by the detector 13 is subjected to frequency analysis using something like a spectrum analyzer 14, (A) when receiving reflected light from a stationary part, only a DC component is found.
Old) When receiving reflected light from a moving part, the frequency component ``■'' becomes dominant.

Here, V indicates the moving speed of the moving part, and d indicates the diameter of the laser irradiation spot. Further, reference numeral 15 in the figure is an X/Y protuberance linked to the spectrum analyzer 14 and the laser beam scanning section 12.

Furthermore, the laser beam was scanned over the surfaces 1 and 2 as shown by the laser beam trajectory 4, and the peak spectrum of the detected output was measured. The results are shown in FIG.

From the figure, it is clear that the spectrum of the light receiver changes suddenly between the stationary plane 1 and the moving plane 2. The above allows the boundary between two surfaces to be confirmed. In FIG. 2, the vertical axis indicates the peak of the spectrum, and the horizontal axis indicates the position on the surface.
According to the above-described embodiment of the present invention, moving parts and stationary parts cannot be easily distinguished by scanning with a laser beam or the like and can be distinguished by changes in speckles.

The above method has the remarkable advantage that the movement (deviation) of the end face of a metal tape or the like can be detected and measured in a non-contact manner using a reflective method. In the present invention, the embodiment described above uses a spectrum analyzer to identify the peak position of a fluctuating signal, but it can also be achieved by simply using a frequency filter. Furthermore, as a method of scanning the laser beam, the object surface may be scanned continuously at a speed sufficiently slow compared to the speed of the moving surface, or it may be shifted little by little in stages and then stopped. You can also take the spectrum. (In the example, a method of scanning the laser beam stepwise is explained.) Further, the illumination of the surfaces 1 and 2 by the laser beam is not particularly limited, but in the case of spot illumination, the size is preferably about lOpmφ. Even in the case of an oval illumination, it is preferable that the direction of movement of the moving surface 2 is in the direction of the minor axis. In addition, this invention has surface 1,
2 move with a speed difference, for example, surface 1
Even if the surface 2 moves at a slow speed and the surface 2 moves faster than the surface 1, the identification is easy.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating a part of the configuration of the present invention using a perspective view, and FIG. 2 is a diagram showing an example of a signal obtained by a detector. DESCRIPTION OF SYMBOLS 1... Stationary surface, 2... Moving surface, 2a... Edge of moving surface, 3... Laser beam, 4... Laser beam trajectory, 5...
...Reflected light of laser light, 11...Laser light oscillation section, 1
2... Laser beam scanning section, 13... Detector, 14...
Spectrum analyzer, 15...XY protomet.

Claims (1)

[Claims] 1. A continuous output laser, an optical system that converges the laser beam near the boundary between two members having a speed difference and scans it continuously or stepwise, and receives reflected and scattered light of the laser beam. 1. An end detection device for a moving surface, comprising a light receiving system and a spectrum analyzer for measuring the frequency spectrum of a detected electric signal, and detecting a boundary position between two members based on a change in the spectrum. 2. The end detection device of a moving surface according to claim 1, wherein the optical system includes an ultrasonic modulation element for deflecting laser light.