JPS63290966A - Noncontact type speed detecting device - Google Patents

Abstract

PURPOSE:To detect the moving speed of an object body stably by comparing the outputs of plural BPFs which pass detection signals of center frequencies corresponding to relative speeds with reference values. CONSTITUTION:A noncontact type speed detector is equipped with a composite filter 9 formed by arranging plural spatial filters 3 successively on the same plane. Then the filters 3 output spatial frequency signals proportional to their moving speeds when moved in parallel to the object body of speed detection. The BPF F1-Fn are provided corresponding to the center frequencies to be detected and comparators C1-Cn compare the detection signals psi1-psin with reference values theta1-thetan. A control circuit 10 specifies the BPFs and the moving speed of the object body is detected from the center frequencies inputted to the specified BPFs.

Description

[Detailed Description of the Invention] Purpose of the Invention (Industrial Field of Application) The present invention is useful for detecting ground speed by being mounted on a moving object such as a means of transportation, or for use in a predetermined device such as a line speed detection device in a manufacturing industry. This relates to a non-contact speed detection device that is installed at a certain location to detect the moving speed of paper and is used for sipping.

(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. 4, this device includes a spatial filter 3 that receives reflected light from a speed-detected object 1 via a lens 2, and a spatial filter that transmits signals of undamaged unevenness outputted from the spatial filter 3. A differential amplifier 4 that outputs a signal with a frequency f, a self-tracking type 1 ranking filter 5 that extracts a center frequency fc from the signal with a spatial frequency f, and a ranking filter 5 that extracts a center frequency fc from the signal with a spatial frequency f.
It is comprised of a calculating means 6 for determining the moving speed V of the object 1 to be detected based on the above, and a display 7 for displaying the moving speed V in digital or analog form.

In this type of speed detection device, the spatial filter 3 includes a plurality of light-receiving elements 8 arranged at regular intervals in the same plane so that they are parallel to each other, and a plurality of light-receiving elements 8 are A structure in which regularly grouped light receiving elements 8 are grouped into a first light receiving element group and the remaining light receiving elements 8 are formed into a second light receiving element group Bn is generally used, but it is complicated and expensive. In order to avoid the use of a self-tracking type (~racking filter), as shown in FIG.
is the first detection element group A2n-1, and the remaining light-receiving elements 8 marked with 〇 in the first light-receiving element group are defined as the second detection element group A2n, and one of the second light-receiving element groups Bn is The light receiving elements 8 provided at intervals are connected to the third detection element group 132n-1.
and the remaining light receiving elements 8 of the second light receiving element group 3n are
A spatial filter (terminal switching type spatial filter) using a detection element group 32n has also been proposed (Japanese Patent Application Laid-Open No. 52-143
Publication No. 735).

In the terminal switching type spatial filter 3, the output 'J end of the first detection element group A2n-1 and the second detection element group △
2n, the output end of the third detection element group 32n-1,
By appropriately combining the output 'jJ ends of the fourth detection element group B2n, the pitch of the spatial filter 3 is made small when the moving speed V of the object 1 to be detected 1 is low, and the pitch of the spatial filter 3 is made small when the moving speed V of the object to be detected 1 is high. By increasing the pitch of the filter 3, the speed detection device can follow a wide speed detection range.

(Problems to be Solved by the Invention) However, in the terminal switching type spatial filter 3, each detection element group Δ2n-1, A2n, [32n-1, [
Since the output end of the 32n must be switched, the spatial frequency signal processing circuit becomes complicated, and the response time becomes long corresponding to the complexity.

The object of the present invention is to eliminate the need for complex signal processing circuits such as self-tracking type 1 to racking filters, and to eliminate the need for switching the output terminals of multiple detection element groups. To provide a non-contact speed detection device capable of stably detecting the moving speed of an object to be detected without being affected by the speed of movement of the object and with a short response speed.

Structure of the Invention (Means for Solving Problems) The present invention consists of first and second light receiving element groups in which light receiving elements are arranged alternately, and the reflection from a relatively moving speed detected object. a spatial filter that receives light and outputs a spatial frequency signal of a center frequency relative to each relative velocity; , a plurality of band-pass filters each passing a detection signal having a center frequency corresponding to the relative velocity, and a plurality of band-pass filters provided corresponding to each band-pass filter, into which detection signals are input, and a filter that passes detection signals with the same detection signal. A non-control device consisting of a plurality of comparators that compare the values with a predetermined reference value, and an indexing means that determines the center frequency at that time based on the discrimination signal output from each of the comparators and determines the moving speed of the object to be detected. The gist of this paper is a contact type speed detection device.

(Operation) When a signal of unevenness of a speed detected object moving relative to the non-contact speed detection device is input to a spatial filter, the spatial filter outputs a spatial frequency signal.

The spatial frequency from the spatial filter is applied to a plurality of bandpass filters arranged corresponding to the relative speed of the object to be detected, that is, the center frequency of the moving speed divided by predetermined speeds in the speed detection range. Each signal is input. The center frequency fc of the spatial frequency signal has the relationship fc = (m/P)·V, where V is the moving speed of the object to be detected, P is the array pitch, and m is the magnification of the lens. The moving speed V of the non-velocity detected object
A bandpass filter that passes the center frequency fc corresponding to the center frequency fc outputs a detection signal having a large signal level at the center frequency fc. A comparator provided corresponding to each bandpass filter compares the detection signal output from the bandpass filter with a reference value. Since the signal level of the reference value is determined in advance, the comparator distinguishes between the bandpass filter that has passed the center frequency fc and other bandpass filters based on the difference in signal level. From the determination result, the indexing means calculates the center frequency fc and the moving speed υj of the object to be detected.

(Example) 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 on which the object is being detected and detects the relative speed of the object. The description will be made according to the drawings, but the description of the same constituent elements as those of the prior art will be omitted, and the explanation will mainly be given to the different constituent elements based on the drawings.

As shown in FIG. 1, the non-contact speed detection device includes a composite spatial filter 9 formed by a plurality of spatial filters 3 arranged side by side on the same plane.

The spatial filter 3, like the conventional spatial filter,
A plurality of light receiving elements 8 having the same optical characteristics are arranged parallel to each other and at equal intervals, and the plurality of light receiving elements 8
Among them, every other light receiving element 8 is grouped as a first light receiving element group, and the remaining light receiving elements 8 are set as a second light receiving element group Bn.

The light receiving elements 8 of the first light receiving element group ○ and the second light receiving element group Bn of each of the spatial filters 3 are spaced apart at the same arrangement pitch P, and the light receiving The element 8 and the light-receiving cable 8 of the second light-receiving element Bn are shifted by 1/2 of the arrangement pitch P.

Then, when each spatial filter 3 is moved relatively parallel to the speed detected object such as a road, the first and second
The light-receiving element group An, 13n inputs the signal of the unevenness of the object to be detected through the lens, and when the array pitch P and the lens magnification m are constant, from the relational expression fc - (m/P> ・V) , outputs a spatial frequency signal with a center frequency fc proportional to the moving speed.

Next, in order to remove low-frequency noise from the spatial frequency signals from each of the light receiving element groups An and Bn, a differential amplifier 4 arranged corresponding to each spatial filter 3 is connected to the first light receiving element group An. The output signal and the output signal of the second light receiving element group Bn are input. Then, the differential amplifier 4 outputs the same extracted signal Φ with an improved S/N ratio, which is passed through the bandpass filter F arranged corresponding to the plurality of differential amplifiers 4.
1, F2, and F3 to Fn.

The band pass filter "1 to Fn is a speed expressed by an integer such as 1 km/h, 2 km/h, for each relative speed of the object to be detected, that is, for each predetermined speed divided within the speed detection range. The number is determined by the speed detection range and speed resolution, that is, the unit of speed display, etc. For example, if the moving speed V is set to about 2
1 km/h in the speed detection range up to 00 km/h
When detecting in units, there are 200 bandpass filters [1 to Fn.

The band pass filters F1 to F'n are provided corresponding to the center frequencies detected at the relative speed, and each has a corresponding center frequency -t'ci, fC2, f.
It is configured to have a filter characteristic that passes through C3 to fCn. Therefore, each bandpass filter F1 to Fn has a frequency pass band over the speed detection range, and the bandpass filter that passes the center frequency, that is, the band corresponding to the relative speed at that time. The pass filter outputs the detection signal with the highest signal level.

For example, when the moving speed V of the object to be detected matches the relative speed Vi, the band pass filter C set corresponding to the center frequency f1 of the relative speed i is set at the center frequency fc at which the signal level is highest. However, if they do not match, a detection signal having a center frequency fci with a smaller signal level is output.

Next, the band pass Filters F1 to Fn
Comparators C1, C2, C3 to O with stages C corresponding to
n is the detection signal v1 to 14frl and the reference value θ1.0
Compare with 2.03~en.

Each of the reference values 01 to en has a predetermined signal level, and the detection signal ψ1.14/2.14/3 to riton with a high signal level is input] Only the comparator is an L level (zero potential) determination signal Control circuit 10 using SG as next stage indexing means
The comparator to which the low signal level detection signal is input outputs an H level (plus potential) discrimination signal SG to the control circuit 10.

The control circuit O specifies a bandpass filter based on this discrimination signal SG, and predetermines the moving speed of the detected object from the center frequency input to the specified bandpass filter. The display drive circuit 11 displays the determined moving speed V on the display 7.
Display digitally or analogously.

Next, the operation and effect of this embodiment will be described. The non-contact speed detection device configured as described above is mounted on the rear of a vehicle, and the vehicle is moved on the road. At this time, when the road is dark, such as at night, the road surface is illuminated with light from a floodlight or the like.

Since there is information on unevenness such as patterns, differences in gloss, dirt, unevenness, etc. on the road, signals of various frequencies are mixed and input to the composite spatial filter 9 depending on the pattern. Then, the first light receiving element group An and the second light receiving element group Bn of the spatial filter 3 generate a composite voltage proportional to the amount of reflected light as an output signal.

1.2nd light receiving element group An in the spatial filter 3,
The 13n spatial frequency signal is input to the differential amplifier 4, where low-frequency noise is removed and the S/N ratio is improved. The extracted signal Φ output from the differential amplifier 4 is inputted in parallel to a plurality of bandpass filters [1 to [n], but each of the bandpass filters F1 to [n has a different frequency pass narrow band. Therefore, the extracted signal Φ with the center frequency fc for the relative velocity vi at that time passes through one of the bandpass filters.
The detection signal output from Fn outputs a detection signal having the center frequency fc with the highest signal level.

Those detection signals @v1~14fn are from the funparators C1~
On, it is compared with the corresponding reference value θ1 to On, and the center frequency fc with a high signal level is input to the control circuit 10 as an L level (zero level) discrimination signal SG. The control circuit 10 discriminates the corresponding bandpass filter based on the discrimination signal SG.

Since each bandpass filter F1 to FD corresponds to the center circular wave number of the relative velocity, the control circuit 10 determines the moving speed V based on the bandpass filter specified by the control circuit 10, and the display drive circuit 11 on the display 7.

As described above, in this embodiment, a plurality of band-pass filters F1 to Fn are arranged in parallel, and the center frequency corresponding to the relative velocity is passed through these band-pass filters F1 to Fn. Type 1 - It becomes possible to track a non-contact speed detection device over a wide speed detection range without using a racking filter or without switching the terminals of the detection element group. Therefore, the speed detecting device of this embodiment has a simple circuit, a fast response speed, and unlike the terminal switching type speed detecting device, the speed detecting device of this embodiment has a conventional technology that uses self-tracking type 1 to racking filters. There is no need to switch the pressure end to change the pitch P, and the moving speed can be accurately detected with a fast response speed regardless of the moving speed of the object to be detected.

The present invention is not limited to the embodiments described above, but can be implemented in the following embodiments as long as the technical idea thereof is followed.

(1) As shown in Figure 2, two sets of image sensors-1
2 and 13 are used as a composite spatial filter, and the pixels of each image sensor 12 and 13 (shaded areas in FIG. 2) are used as light receiving elements 8, and they are arranged at the same pitch as in the example. The image sensors 12 are grouped to function as a spatial filter.
One set of image sensors 12 among the 13 image sensors 13 is rotated by 90 degrees in the same plane with respect to the other image sensors 13, and the moving speed VX of the X-direction component of the speed detected object 1 is detected by the image sensor 12, The image sensor 13 detects the moving speed Vy of the Y direction component, and both image sensors 12 and 13 detect the two moving speeds v.
The composite vector velocity Vz of ×, Vy is detected.

(2) As shown in Fig. 3, one spatial filter 3 is installed parallel to each velocity detection object, and the spatial frequency signal is transmitted from the spatial filter 3 to the corresponding differential amplifier 4. can be input in parallel to a plurality of band-pass filters F1 to Fn, which are arranged in correspondence with the center frequency of the relative velocity. In this aspect as well, in addition to the same effects as in the embodiment, it is possible to implement with one spatial filter.

(3) The non-contact speed detection device of the present invention can be applied even when the object is fixed and the object to be detected is moving. It is also possible to use the signal etc. in a device that controls the movement of a speed-detected object by transmitting a signal or the like to the implanter 1.

Effects of the Invention As detailed above, the present invention enables speed detection over a wide speed detection range without using a self-following tracking filter or without changing the arrangement pitch by switching the terminals of a plurality of detection element groups. The moving speed of the object to be detected can be detected accurately and with a short response speed, the speed detection circuit can be simplified, and the speed in two-dimensional directions can also be detected.

[Brief explanation of the drawing]

Figures 1 to 3 are drawings related to the present invention, where Figure 1 is a configuration diagram of the main parts of an embodiment, Figure 2 is a diagram of the main parts of another example, and Figure 3 is a diagram of the main part configuration when only one spatial filter is used. FIG. 4 is a block diagram of main parts of another example of the embodiment, FIG. 4 is a block diagram of main parts of a conventional technique, and FIG. 5 is a block diagram of a spatial filter of a conventional technique. 3... Spatial filter, 4... Differential amplifier, 8...
Light receiving element, 9... Composite spatial filter, 1o... Indexing means (control circuit), An... First light receiving element group, 1
3n... second light receiving element group, C1-Cn... comparator, F1-Fn... band pass filter, fc.
・・Center frequency, ■・・Movement speed

Claims (1)

[Claims] 1. The light receiving element is composed of first and second light receiving element groups arranged alternately, and receives reflected light from a relatively moving object to be detected at a relative speed. Spatial filters that output spatial frequency signals with opposing center frequencies; Spatial filters that are provided as many times as there are relative velocities to be detected, input the spatial frequency signals from the spatial filters, and detect detection signals with center frequencies corresponding to the respective relative velocities. A plurality of band pass filters are provided corresponding to each band pass filter, and detection signals from the band pass filters are input.
a plurality of comparators that compare the detection signal with a predetermined reference value; and an determining means that determines the center frequency at that time based on the discrimination signal output from each of the comparators, and determines the moving speed of the speed-detected object. A non-contact speed detection device consisting of. 2. The non-contact speed detection device according to claim 1, wherein said spatial filters are provided in the number of relative velocities to be detected, and are connected in correspondence with bandpass filters.