JPS6276470A - Moving acceleration detector for moving body by using pyroelectric sensor - Google Patents

Abstract

PURPOSE:To improve responsiveness with a comparatively simple constitution, to detect the acceleration of a quickly moving body and to minimize an error by detecting the acceleration of the moving body with the aid of three difference signals obtained by using three pairs of pyroelectric sensors (6 units). CONSTITUTION:The pyroelectric sensors 1a-1f output detection signals S1-S6 accompanied with time delay in accordance with the moving speed of an incident infrared ray in the incident order. The detection signals S1 and S2 are given to a differential amplifier circuit 3a, which outputs a difference signal S7. On the other hand, the group of the detection signals S3 and S4 and that of the detection signals S5 and S6 are given to differential amplifier circuits 3b and 3c, respectively. The differential amplifier circuit 3b outputs a differential signal S8 with a slight hourly delay from a differential signal S7. The differential amplifier circuit 3c outputs a detection signal S9 with a slight hourly delay from the difference signal S8. Since the rise of the take a difference between the steeply changing parts of the pyroelectric sensors 1a-1f even if the rise of the detection signals S1-S6 is slow, the difference signals S5-S7 can obtain a sufficiently large difference output.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to a device for detecting the moving acceleration of a moving object, and particularly to a device for detecting the moving acceleration of a moving object using a pyroelectric optical sensor. Regarding.

(Prior art) ゛As a moving acceleration detection device using pyroelectric sensors, three pyroelectric sensors A, B,
A conceivable method would be to arrange C, detect the moving speed, and then calculate the moving acceleration. The moving speed of a moving object is detected as follows using two of the three pyroelectric sensors.

For example, when the pyroelectric sensors A and B receive infrared rays from a moving object, a detection signal S as shown in FIG.
Output a and Sb in order. Next, these detection signals Sa
, Sb respectively reach a predetermined setting level Vo, a time difference T1 is detected. The separation distance between the two pyroelectric sensors, which is known in advance, is divided by this time difference TI, and the speed of the moving object is detected from the division result (L/TI).

Furthermore, the acceleration of the moving object is determined by the pyroelectric sensors A, B, and C.
is detected as follows. First, the velocity Vl of the moving object is detected from the detection signals of the pyroelectric sensors A and B, and further, the velocity V2 of the moving object is detected from the detection signals of the pyroelectric sensors B and C using the procedure described above. Then, by dividing these speed changes V2-Vl by the time difference T, the acceleration of the moving object is detected.

(Problems to be Solved by the Invention) However, it is generally known that the response speed of pyroelectric optical sensors is not very fast.

For this reason, although this type of pyroelectric sensor can be used to detect the acceleration of objects moving at low speeds, it is difficult to use the sensor output necessary to detect the acceleration of objects moving at high speeds. I can only get it. Therefore, the conventional detection device has a problem in that it is not suitable for detecting the moving acceleration of a high-speed moving object.

Furthermore, if the level VO set for speed/acceleration detection described above is set high enough to match a sufficiently large detection signal, if the pyroelectric sensor outputs a small detection signal that is less than the set value. , this causes the inconvenience of not being detected.

On the other hand, if the setting level VO is set low, there is a risk that the pyroelectric sensor may respond to infrared rays from a moving object other than the moving object whose speed or the like is to be detected, causing malfunction. Therefore, in the conventional detection device, the level setting value must be appropriately changed depending on the magnitude of the detection signal of the pyroelectric sensor, but such a change is very troublesome in terms of use of the device.

Furthermore, if there are variations in the sensitivity and response speed of each pyroelectric sensor, the rise time of the detection signal of each sensor will be different, resulting in a problem that the accuracy of speed/acceleration detection will deteriorate. For example, suppose that when speed is detected by sensors A and H, one sensor B has low sensitivity, so that sensor B outputs a low-level detection signal Sb° as shown in FIG. 4(B). . At this time, the time difference between the rain detection signals Sa and Sb' reaching the set level Vo is T2. This time difference T2 is longer than the time difference Tl when the aforementioned detection signals Sa and Sb of the same level are output. Or, the opposite may be the case. Therefore, the accuracy of acceleration detection deteriorates.

If an attempt is made to solve the influence of such variations in sensor characteristic values on acceleration detection using known technical means, the circuit configuration of the detection device will become very complex.

The present invention was made in view of the above circumstances, and is capable of not only detecting the moving acceleration of an object moving at low speed, but also detecting the acceleration of an object moving at low speed.
It is an object of the present invention to make it possible to reliably detect the moving acceleration of an object moving at high speed.

Furthermore, another object of the present invention is to easily reduce acceleration detection errors caused by variations in sensitivity and response speed between pyroelectric sensors.

(Means for Solving the Problems) In order to achieve such an object, the present invention outputs a detection signal in response to light from a moving object within a sensing area, and also outputs a detection signal in response to light from a moving object within a sensing area. Three pairs (six) of pyroelectric sensors are arranged in a row at predetermined intervals along the movement direction, and three pairs of detection signals are individually given from the three pairs of pyroelectric sensors, and the six pairs are eleventh second and third differential signal output means each outputting a differential signal in response to a detection signal constituting the differential signal output means; and signal processing for detecting a time difference between the differential signals of the differential signal output means. and an arithmetic processing means for calculating the moving acceleration of the moving object based on the time difference between the differential signals and the separation distance of the pyroelectric sensor.

(Function) As a result of a time lag occurring in the outputs of the pyroelectric sensors depending on the moving direction of the moving object, each of the differential signal output means provides a differential signal. When the time difference between the three differential signals is detected, the arithmetic processing means calculates the moving speed of the moving object based on this time difference and the previously known separation distances of the three pairs of pyroelectric sensors. V1. Calculate V2.

Furthermore, the arithmetic processing means calculates the change in the moving speed V2-
The acceleration of the moving object is calculated by dividing Vl by the time difference ΔT.

On the other hand, since the differential signal output means provides a differential output of a sharply changing portion of the detection signal of the pyroelectric sensor, it is possible to magnify and extract changes in the sensor output. This improves the response speed of this detection device, making it possible to detect even the moving acceleration of relatively high-speed moving objects, and eliminating errors in acceleration detection due to variations in sensitivity and response time of each pyroelectric sensor. Significantly reduced.

(Example) Hereinafter, the present invention will be described in detail based on an example shown in the drawings. FIG. 1 is a circuit diagram schematically showing the configuration of a moving acceleration detection device that also detects the moving direction and speed of a moving object, using a pyroelectric sensor according to an embodiment of the present invention.

Each of the pyroelectric sensors 1a to 1f of this embodiment has a sensing area that detects infrared rays from within a certain range. The pyroelectric sensors 1a-1f are integrally formed as a sensor element 20, as shown in FIG. This sensor element 20 has a structure in which infrared light receiving sections 22a to 22f are arranged on a pyroelectric substrate 21 at a certain distance apart and substantially parallel to the moving direction. These infrared light receiving parts 22a to 22f are the pyroelectric sensor 1a.
-1f, respectively. The pyroelectric substrate 21 is made of, for example, a pyroelectric material such as PbZrO3-PbTi03 (PZT)-based solid solution porcelain. One end of extraction electrodes 23a to 23f is connected to each of the infrared light receiving sections 22a to 22f, respectively. The other ends of the extraction electrodes 23a to 23f are respectively connected to impedance conversion circuits 2a to 23f, which will be described later.
External connection terminals 24a to 24 connected to each human power section of 2r
It ends with f.

Such pyroelectric sensors la to 1r are impedance conversion circuits 2a composed of field effect transistors, etc.
~2f, the negative (-) of the differential amplifier circuits 3a to 3c.
Connected to each positive (+) input terminal. Each output terminal of the differential amplifier circuits 3a to 3c is connected to a mixer 4 via a DC blocking capacitor C. The mixer 4 is connected to a polarity determining circuit 5 and a waveform shaping circuit 6.

The waveform shaping circuit 6 is connected to a trigger circuit 7, which is further connected to one input terminal of a counting circuit 8. An oscillation circuit 9 is connected to the other input terminal of the counting circuit 8. The output side of this counting circuit 8 is connected to an arithmetic processing circuit IO. The arithmetic processing circuit 10 is connected to a drive circuit 2 that drives a movement direction/speed/acceleration display 12. Further, the output side of the polarity discrimination circuit 5 is connected to this drive circuit +1. Note that the driving circuit 11 and the display 12 are not necessarily essential elements of the present invention, since the moving direction, speed, and acceleration of a moving object can be detected by the outputs of the polarity determining circuit 5 and the arithmetic processing circuit IO.

Also, on the front of the pyroelectric sensors a to 1f, as shown in Fig. 5(A)
As shown in (B), if a method such as attaching an imaging lens 100 or forming an image by reflection from a concave mirror 101 as shown in FIG.・Can detect acceleration.

In addition, in FIG. 3, 102 indicates a sensor light receiving surface.

Next, the operation of this embodiment will be explained.

For example, assume that a moving object is moving from a pyroelectric sensor a toward a pyroelectric sensor d. When infrared rays irradiated from a moving object enter the sensing region of each pyroelectric sensor in sequence, each pyroelectric sensor a to 1r
As shown in Figure (A), detection signals 81 to S6 with time delays depending on the moving speed of the incident infrared rays are output in the order in which the infrared rays are incident.

The detection signals Sl and S2 are provided by the impedance conversion circuit 2a,
2b to the differential amplifier circuit 3a. As a result, the differential amplifier circuit 3a outputs a differential signal S7 as shown in FIG. On the other hand, the detection signals S3 and S4
are given to the differential amplifier circuit 3b via the impedance conversion circuits 2c and 2d, and the detection signals S5 and S6 are given to the differential amplifier circuit 3c via the impedance conversion circuits 2e and 2f. As a result, the differential amplifier circuit 3b outputs the differential signal S8 with a slight delay in time from the differential signal S7, as shown in FIG. 3(C). In addition, the differential amplifier circuit 3C
outputs the detection signal S9 with a slight time delay compared to the differential signal S8. These differential signals S7, S8, S9 are connected to DC blocking capacitors CI, C2
, C3 to the mixer 4, respectively. The mixer 4 combines the differential signals S7, S8, and S9 and outputs a composite signal SIO having positive or negative polarity as shown in (E) or (F') in the figure. This composite signal Sl
O is applied to the next stage polarity discrimination circuit 5 and waveform shaping circuit 6.

The polarity determining circuit 5 supplied with the composite signal SIO determines the moving direction of the moving object by determining the positive or negative polarity of this signal. For example, as described above, when the moving object moves in the direction from the pyroelectric sensor 1a to the pyroelectric sensor tb, the polarity of the composite signal SIO is set to be positive. Then, when the moving object moves in the opposite direction to the above direction, the detection signal S2 is output before the detection signal S+, so these differential signals are combined (the polarity of the signal SIO is It becomes negative as shown in FIG. The moving direction of the moving object is displayed on the display I2.

On the other hand, the waveform shaping circuit 6, which receives the composite signal SlO from the mixer 4, shapes the waveform of this signal into a rectangular pulse Sll as shown in FIG. This rectangular pulse Sll is applied to the trigger circuit 7 and converted into pulse signals 512a and 12b as shown in FIG. This pulse signal 5I
The pulse width of 2a is the time difference between the two differential signals s7 and S8 included in the composite signal SIO, that is, the pair of pyroelectric sensors Ia.

Distance M from 1b to another pair of pyroelectric sensors lc11d
(corresponding to the distance of two pitches of the arrangement pitch of the light receiving sections shown in FIG. 2) corresponds to the time during which the incident infrared rays travel. Similarly, the pulse width of the pulse signal 512b is determined by the time difference between the two differential signals S8 and S9 included in the composite signal slo, that is, from the pair of pyroelectric sensors lc and ld to the other pair of pyroelectric sensors Ie and If. The distance corresponds to the time it takes the incident infrared rays to travel. The transit time of this incident infrared rays corresponds to the travel time of the moving object.

Such a pulse signal 512aS 12b is given as one input of the counting circuit 8. Then, as the other input of the counting circuit 8, a lock pulse SI3 is applied from the oscillation circuit 9 as shown in FIG.
By counting the number of pulses included in each AND signal of 2aS 12b and S13, a count value corresponding to the travel time of the moving object is obtained.

The arithmetic processing circuit 10 multiplies each count value by the period of one clock pulse to obtain pulse signals 512a, 12.
The pulse widths Ta and Tb of b are respectively calculated. and,
By dividing the distance corresponding to two pitches of the arrangement pitch of the light receiving sections described above by the pulse widths Ta and Tb, the moving speed Vl of the infrared rays when passing through the pyroelectric sensors 1a to ld and the pyroelectric The moving speed V2 of the pyroelectric sensor when passing through the sensor IC-1 is determined. From the moving speeds V1 and V2 of the incident infrared rays, the moving speed of the moving object in each sensor section is determined. The speed calculation result (1) is given to the drive circuit 11, so that the speed of the moving object is displayed on the display 12.

Note that when using a lens or concave mirror as shown in Figure 5, the actual velocity/acceleration of the moving object differs from the velocity/acceleration on the sensor light receiving section depending on the optical system, so further calculation processing may be required. good.

Furthermore, the arithmetic processing circuit IO calculates the calculated moving speed V1
, V2, and the pulse signal 512a shows this variation as shown in FIG.

The acceleration of the moving object is calculated by dividing by the standing time difference t2-tl of S l 2b. The calculation result of this acceleration is given to the drive circuit 11, so that the acceleration of the moving object is displayed on the display 12.

By the way, as can be understood from the waveform diagrams shown in FIGS. 2(A) to 2(D), the differential signals S5, S6, and S7 are steeply changing portions of each detection signal of the pyroelectric sensor La-1f. In order to take the differential, it is assumed that the rise of each of the detection signals 81 to S6 is slow, but the rise of the peak portion of the differential output is extremely fast. Therefore, even when detecting a high-speed moving object, a sufficiently large differential output can be obtained.・Detection of speed and acceleration is also performed reliably. Also,
Even if there are variations in the sensitivity and response speed of each pyroelectric sensor, it hardly affects the difference in the rise time of the two differential signals, so it is possible to accurately detect the velocity and acceleration of a moving object. I can do that.

In the embodiment, a positive voltage signal from the polarity discrimination circuit 5 means that the moving object moves from the shape sensor Ia to the pyroelectric sensor If, and a negative voltage signal means the opposite. Although it has been meant that the object moves in the direction, the relationship may be reversed.

Further, in the embodiment, the moving direction of the moving object is detected based on the polarity of the composite signal SIO, but this is done by determining the polarity of at least one of the differential signals S5, S6, and S7. Of course, it can be detected.

Furthermore, in the example, a pyroelectric sensor that generates a voltage of the same polarity with respect to incident infrared rays is used, and therefore,
A differential amplifier circuit is provided as means for obtaining differential signals of detection signals from each pyroelectric sensor.

However, if the pair of pyroelectric sensors generate voltages of opposite polarity with respect to incident infrared rays, adder circuits are provided in place of the differential amplifier circuits 3a, 3b, and 3c, respectively. These differential signals S5, S6, S7
It is recommended that you obtain the following.

Furthermore, in the embodiment, six sensors (three pairs) are arranged, but if more sensors are added, that is, seven or more sensors are arranged, the average value of velocity/acceleration may be changed. The detection accuracy can be improved.

The pyroelectric sensor according to the present invention is usually used as an infrared sensor, but it is also sensitive to visible light, so for example, when a moving object is irradiated with visible light, the reflected light is detected. It may also be detected.

(Effects) As described above, the device according to the present invention provides three differential signals obtained using three pairs (six) of pyroelectric sensors.
Since the acceleration of a moving object is detected, the response of the device can be improved with a relatively simple configuration, making it possible to detect the acceleration of a high-speed moving object. Errors in acceleration detection due to variations can be reduced.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an outline of the configuration of a device for detecting moving acceleration of a moving object using a pyroelectric sensor according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a sensor element used in this embodiment. , FIG. 3 is an explanatory diagram of the operation of the apparatus shown in FIG. 1, FIG. 4 is an explanatory diagram of rapid detection by a conventional detection device, and FIG. 5 is an explanatory diagram of another embodiment of the present invention. 1a-1r...pyroelectric sensor, 2a-2r impedance conversion circuit, 3a-3c...differential amplifier circuit, 4...
mixer, 5... polarity discrimination circuit, 6... waveform shaping circuit,
7...Trigger circuit, 8...Counting circuit, 9...Oscillation circuit, 10...Arithmetic processing circuit, II...Drive circuit, 12
...Moving direction/speed/acceleration indicator.

Claims (3)

[Claims] (1) Three sensors that output detection signals in response to light from a moving object within the sensing area, and are arranged in a line at predetermined intervals along the moving direction of the moving object.
Pairs (6 pieces) of pyroelectric sensors and 3 pairs of detection signals from the 3 pairs of pyroelectric sensors are individually given, and differential signals are output respectively in response to the detection signals forming each pair. first, second, and third differential signal output means for detecting a time difference between the differential signals of the differential signal output means; a signal processing means for detecting a time difference between the differential signals of the differential signal output means; and a time difference between the differential signals and the pyroelectric sensor. 1. An apparatus for detecting moving acceleration of a moving object using a pyroelectric sensor, comprising: arithmetic processing means for calculating the moving acceleration of the moving object based on the separation distance of the moving object. (2) Detection of moving acceleration of a moving object using the pyroelectric sensor according to claim 1, which is provided with a condensing lens that focuses only light from within the sensing area onto the pyroelectric sensor. Device. (3) Claim 1 comprising a concave border that focuses only light from within the sensing region onto the pyroelectric sensor.
A device for detecting the moving acceleration of a moving object using the pyroelectric sensor described in 1.