JPH01202666A - Noncontact velocity detector - Google Patents

Abstract

PURPOSE:To make an output characteristic variable in a wide range with the number of lattices of a space filter fixed, by altering an angle of support of the space filter supported rotatably to make an apparent pitch of a photodetector thereof variable. CONSTITUTION:Reflected light from an object 11 intended to detect a velocity is turned to a parallel beam with a lens 15 passing through a pit 14a of a light shielding plate 14 arranged at a focal position of the lens 15 and received with a space filter 18 in which (n) photodetectors (lattices) are arranged in the same plane so as to be parallel with one another at a fixed pitch P. The filter 18 is fastened on a filter fixing plate 17 fixed on a rotating shaft 16. Then, when the rotating shaft 16 is rotated with a motor to set an inclination (a support angle of the filter 18) of the filter fixing plate 17 at theta, an apparent light receiv ing width Wtheta of photodetectors for the optical axis L1 of the lens 15 gives a Wcostheta (W: light receiving width) and hence, an apparent pitch P amounts to Pcostheta. In this manner, an output characteristic is made variable by varying the pitch P apparently and the optimum apparent pitch Ptheta corresponding to a velocity is selected to perform a measurement.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention can be mounted on a moving object such as transportation to detect ground speed, or placed at a predetermined position such as a line speed detection device in the paper industry. The present invention relates to a non-contact speed detection device used to detect the moving speed of paper.

[Prior Art] Conventionally, as a device for detecting the speed of an object to be detected in a non-contact manner, there has been a speed detection device using a spatial filter.

As shown in FIG. 7, this device is a space in which a plurality of light-receiving elements 3 are arranged parallel to each other at a constant pitch in a space in which reflected light from a speed-detected object 1 is reflected through a lens 2. The light is received by the filter 4 (a pair of eye-shaped filters), and the output signal of the same spatial filter 4 is used by the differential amplifier 5 to calculate the spatial frequency f.
At the same time, the tracking filter 6 extracts the center frequency fc from the signal f. And the detection means 7
detects the moving speed V (= (fc-P)/m, where P is the arrangement bit of the light-receiving element 3 and m is the lens magnification) of the object 1 based on the center frequency fc, etc., then the speed ■ The display unit 8 displays digitally or analogously.

In this apparatus, as a method for changing the output characteristics of the speed signal according to the moving speed V of the speed detected object 1, there is a method of changing the optical system magnification.

Further, as the spatial filter 4, the light receiving elements 3 are arranged at appropriate pitches (P/2>) as shown in FIG. Group 3 is set as the first detection element group A2n-1, and the remaining light receiving elements 3 marked with 〇 are sent to the first light receiving element group as the second detection element group A2n.
At the same time, in the second light receiving element group 3n, the light receiving elements 3 similarly provided at intervals are set as the third detecting element group 32n-1, and the remaining light receiving elements in the second light receiving element group [3n] A spatial filter has been proposed in which the light receiving element 3 is used as the fourth detection element group 32n. Then, the outputs of the first to fourth detection elements A2n-1, A2n, 32n-1, 132n @
9a.

By appropriately combining 9b, 9c, and 9d, the output characteristics of the speed signal can be changed by extracting light receiving element outputs at arbitrary pitch intervals.

That is, when the moving speed (V) of the detected object 1 is low, the pitch of the spatial filter 4 is decreased, and when the moving speed V of the detected object 1 is high, the pitch of the spatial filter 4 is increased to detect the speed. The device is capable of following a wide speed detection range (Japanese Patent Application Laid-Open No. 143735/1983).

[Problems to be Solved by the Invention] However, in the former method (changing the optical system magnification), there is a problem that the adjustment of the optical system becomes complicated and the circuit becomes complicated and large. In the latter method (terminal switching type spatial filter), the number of gratings (the number of light-receiving elements) increases, and the process is gradual in principle and is not arbitrary. In addition, the number of required elements is large, the processing of connections and output lines is complicated, the peripheral circuits are large, the loss is 1 to high, and it is necessary to combine element characteristics and optical base h1 precisely.

The purpose of this invention is to solve the above problems, and to make it possible to make the output characteristics variable while keeping the number of grids of the spatial filter constant with a simple configuration, and the variable range is wide and the settings are highly arbitrary. Our objective is to provide a non-contact speed detection device.

[Means for Solving the Problems] In order to achieve the above-mentioned object, the present invention is directed to transmitting the reflected light of an object to be detected at speed through a lens into a plurality of light-receiving elements at a constant pitch so as to be parallel to each other within the same plane. In a non-contact type speed detection device, the speed of the object to be detected is measured based on the output signal of the spatial filter by receiving light through a spatial filter arranged in the spatial filter, A light shielding member having a small hole is provided at the focal position of the lens in between, and the spatial filter is passed through the spatial filter for the reflected light of the speed-detected object that passes through the small hole of the light shielding member and becomes a parallel beam at the lens. The gist of the non-contact speed detecting device is to provide a non-contact speed detecting device which is movably supported and by changing the support angle of the spatial filter, the apparent pitch of the light receiving element of the spatial filter for the reflected light of the speed detected object can be varied. That is.

[Operation] The reflected light from the speed-detected object passes through a small hole in the light-shielding member placed at the focal point of the lens and becomes a parallel beam of light at the lens. The light is received by a spatial filter placed at At this time, by changing the support angle of the spatial filter, the apparent pitch of the light-receiving elements of the spatial filter with respect to the reflected light of the speed-detected object can be varied, and the output characteristics can be changed.

[Example 7] Next, an example will be described in which the present invention is embodied in a non-contact type speed detection device that is mounted on a vehicle that moves relative to the road, which is the object to be detected, and detects the relative speed of the vehicle. This will be explained according to the drawings. In this embodiment, explanations of the same constituent elements as those of the prior art will be omitted, and constituent elements different therefrom will be mainly explained.

As shown in FIGS. 1 and 2, a non-contact speed detection device 12 is arranged at a constant interval from the speed detection object 11. As shown in FIGS. This non-contact speed detection device @12 has a light-shielding shield (case) 13 formed in a box shape, and a light-shielding plate 14 as a light-shielding member is provided on the surface of the light-shielding shield 13 facing the speed detection object 11. There is. A small hole (pinball) 14a is formed in the center of this light-shielding plate, and the reflected light from the speed-detected object 11 enters the light-shielding shield 13 through the small hole 14a.

A lens 15 is supported within the light-shielding shield 13 at a position (focal position) separated from the small hole 14a by its focal length. Therefore, the reflected light from the speed detected object 11 is transmitted through the small hole 14.
The light is inputted through the lens 15 and becomes parallel light rays at the lens 15.

A rotation shaft 16 is rotatably supported on the optical axis L1 of the lens 15 behind the lens 15 in the light-shielding shield 13. The axis L2 of this rotating shaft 16 extends in a direction perpendicular to the optical axis L1, as shown in FIG. A filter fixing plate 17 is fixed to the rotating shaft 16, and a spatial filter 18 having a large number of light receiving elements is fixed to the filter fixing plate 17, as shown in FIGS. 3 and 4. . That is, n number of light receiving elements 01 to Cn are arranged and supported in parallel on the surface of the base 18a at a pitch P, and the light receiving width thereof is W, and the light receiving element groups C1 to cn are arranged and supported in parallel with each other at a pitch P.
It is arranged so as to face 5. The lattice arrangement of the lattice (light-receiving elements C1 to C ports) of the spatial filter 18 is set to be parallel to the axis L2 of the rotation shaft 16 (see FIG. 2).The rotation wheel 16 is driven by a motor (not shown). The tilt angle θ of the filter fixing plate 17, that is, the lens 15
The angle θ (O≦θ≦9) formed by the optical axis L1 of and the fixed plate 17
If the spatial filter 18 is tilted by an amount of The width Wθ is W·COSθ as shown in FIG. Similarly, the apparent pitch (lattice pitch) P of the light receiving element groups 01 to Cn of the spatial filter 18
θ becomes p-cos θ.

In addition, the light receiving element groups C1 to Qn include every other light receiving element C.
2n-1 is connected to a first output terminal (not shown), and another light receiving element C2n is connected to a second output terminal (not shown), and the first and second output terminals are connected to a differential amplifier (
(not shown). This differential amplifier is connected to a tracking filter (not shown). Therefore, the differential amplifier calculates the difference between the outputs of the first output terminal and the second output terminal, and the tracking filter removes the extra components in the output and the light receiving element pitch P.
The frequency that changes at the same pitch as θ is extracted. The moving speed V of the speed detected object 11 is determined from the frequency.

Therefore, by arranging the light receiving element groups 01 to Cn at positions where the horizontal light beam from the lens 15 exists, the rotation axis 16
By adjusting the drive of the spatial filter 18, the apparent pitch (
The grating pitch (Pθ) can be made variable, and in order to make the output characteristics variable, for example, an optimum roughening pitch Pθ can be selected depending on the speed and measurement can be performed at that pitch Pθ.

As described above, the non-contact speed detection device of this embodiment is provided with a light shielding plate 14 having a small hole 14a at the focal point of the lens 15 between the speed detected object 11 and the lens 15, and
At the rear of the lens 15, the light receiving element group C is moved around the rotation axis 16.
A spatial filter 18 is rotatably supported in which a plurality of spatial filters 1 to CD are arranged parallel to each other in the same plane at a constant pitch P, and the reflected light from the speed detected object 11 is filtered through the small hole 14a of the light shielding plate 14. The light passes through the lens 15 disposed at the focal point, converts the light into parallel light, and causes the light-receiving element groups C1 to Qn with an inclination angle θ to receive the light. By changing the angle (tilt angle θ) of the spatial filter 18, the apparent pitch (grating pitch) Pθ of the light receiving elements of the spatial filter 18 can be continuously changed.

In other words, compared to conventional non-contact speed detection devices, the number of grids can be kept constant and the output characteristics can be varied, the variable range is wide, the settings are highly arbitrary, and there is no need to manipulate the signal line, making it more reliable. Furthermore, circuit processing is simple and can be miniaturized. Furthermore, since the lattice arrangement of the spatial filter 18 is not a problem, there is a high degree of freedom in designing the spatial filter.

Note that the present invention is not limited to the above-mentioned embodiment. For example, in the above-mentioned embodiment, the filter fixing plate 1 is
As shown in FIG. The inclination angle θ of the spatial filter 18 may be changed. In that case, the overall structure becomes simpler.

[Effects of the Invention] As described above, according to the present invention, the output characteristics can be made variable while keeping the number of grids of the spatial filter constant with a simple structure, and the variable range is wide and the setting is arbitrary. This provides an excellent effect of providing a non-contact speed detection device with high speed.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the non-contact speed detection device of the present invention, Fig. 2 is a sectional view of the same non-contact speed detection device, Fig. 3 is a plan view showing a spatial filter, and Fig. 4 is a plan view of the same spatial filter. Fig. 5 is an explanatory diagram when the spatial filter is tilted, Fig. 6 is a sectional view of a non-contact type speed detection device for ablation, and Fig. 7 is for explaining a conventional non-contact speed detection device. and FIG. 8 are diagrams for explaining another conventional non-contact speed detection device. 11 is a speed detection object, 12 is a non-contact speed detection device, 1
4 is a light shielding plate as a light shielding member, 14a is a small hole, 15 is a lens, 16 is a rotation axis, C1 to Cn are light receiving elements, 18 is a spatial filter, and Pθ is an apparent pitch. Patent applicant Toyoda Automatic Loom Works Co., Ltd. Representative
Person Patent Attorney On 1) Hironobu 3a

Claims (1)

[Claims] 1. The reflected light of the speed-detected object is received through a lens by a spatial filter in which a plurality of light-receiving elements are arranged parallel to each other at a constant pitch in the same plane. In a non-contact speed detection device that measures the speed of the object to be detected based on an output signal of a filter, a small hole is provided between the object to be detected by speed and the lens at a focal position of the lens. A light shielding member is provided, and the spatial filter is rotatably supported with respect to the reflected light of the speed-detected object that passes through the small hole of the light shielding member and becomes a parallel beam at the lens, and the support angle of the spatial filter is adjusted. A non-contact type speed detection device in which the apparent pitch of a light receiving element of a spatial filter for light reflected from the object to be detected is made variable by changing the speed detection object.