JPS5931116B2 - Intruding object detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intruding object detection device, and more particularly to an intruding object detection device that can detect not only the presence or absence of an intruding object but also its size.

2. Description of the Related Art As a device for detecting an intruding object or a passing object, a light beam alarm device or the like consisting of a light projecting device and a light receiving device has conventionally been used.

However, although such a light beam alarm device can detect the presence or absence of an intruding object, it has been impossible to determine its size.

Incidentally, an intruding object detection device that can identify the size of an object by using a recently developed one-dimensional light receiving diode array (also referred to as an image sensor) has come to be considered.

A conventional intruding object detection device using this one-dimensional light receiving diode array is shown in FIG.

Here, the ■-dimensional light receiving diode array is a linear array of light receiving diode elements of several tens of microns at a pitch of several tens of microns, and has the features of high sensitivity and high resolution. .

In reality, the structure is such that not only the light receiving diode elements but also peripheral circuits for extracting the outputs of the individual light receiving diode elements as serial pulses are formed as an integrated circuit and housed in an IC chip.

Now, in Fig. 1, one-dimensional light receiving diode array 1
A convex lens 2 as a lens system is provided on the front surface of the monitor, and the light beams arriving from the monitoring point pass through the convex lens 2 and
The image is formed on a dimensional light receiving diode array 1.

Therefore, the distance between the one-dimensional photodiode array 1 and the convex lens 2 is A, the distance from the convex lens 2 to the monitoring point is B, the length of the one-dimensional photodiode array 1 is C1, and the monitoring range at the monitoring point is D. Then, there is a relationship D--C.

For example, if A=20mm, B=40m, and C=5mm, then D=10m.

On the other hand, if the size of each diode element is E and the individual monitoring range thereof is F, then similarly F=-E1
There is a relationship.

Here, if E-50 μm (microns) is used and the values of A and B above are substituted as they are, F-10CIrL is obtained.

That is, while the overall monitoring range is 10 m, the individual monitoring range is 10 m, and these individual monitoring ranges do not overlap each other if lens aberrations and the like are ignored.

Therefore, with such a configuration, it is possible to sufficiently detect the intrusion of an object and the size of the object at a relatively distant monitoring position.

However, the apparatus of FIG. 1 suffers from the following drawbacks.

In other words, there is no problem when the monitoring distance is constant, such as when monitoring the ground from the top of a building, but when the monitoring distance is not constant, for example when monitoring an area along the building from the side of the building. In such a case, it is possible that an object may enter the vicinity of the convex lens 1 or may enter far away.
It is difficult to predict the monitoring distance in advance.

Therefore, even if the size of the object is the same, the size of the image on the one-dimensional light receiving diode array 1 is different, such that a distant object is perceived as small even if it is large, and a nearby object is perceived as large even though it is small.

Thus, with the conventional configuration, it is impossible to identify the actual size of the object.

The present invention aims to eliminate the above-mentioned drawbacks of the prior art and provide an intruding object detection device that can detect the size of an intruding object even when the monitoring distance is not constant.

Embodiments of the intruding object detection device according to the present invention will be described below with reference to the drawings.

FIG. 2 shows the optical device portion of the embodiment.

In this figure, two object detection devices shown in FIG. 1 are provided so as to face each other.

That is, the monitoring point is imaged onto the one-dimensional light-receiving diode array 1A through the convex lens 2A serving as a lens system, and is also imaged onto the one-dimensional light-receiving diode array 1B through the convex lens 2B.

Now, suppose that the size of the object 3 in the height direction is H, the distances between the convex lenses 2A and 2B and the object 3 are Ll and L2, and the focal length of the convex lenses 2A and 2B is f, then 1
Dimensional photodiode array IA.

The sizes a and b of the images on 1B can be expressed as follows using the formula for image formation using a convex lens.

Also, (However.

is the installation interval of convex lenses 2A and 2B) above (1) and (2
), by eliminating Ll and L2 according to equation (3), we obtain the following.

As can be seen from equation (4), if the focal length and installation interval of the lenses are determined in advance, the object size H can be determined from the image sizes a and b on the one-dimensional light receiving diode arrays IA and 1B. can.

Furthermore, another point that must be considered is the problem of distinguishing between the background and the intruding object at the monitoring point.

This embodiment focuses on the fact that the background does not change over time, and that the invading object moves and intrudes from a state where it does not exist at the monitoring point.

FIG. 3 shows the photoelectric conversion device portion of the example.

In this figure, the video output of a one-dimensional photodiode array 1A is amplified by an amplifier 10A, and then a slicer 11
A, and is converted by this slicer 11A into a serial digital signal indicating logic "1" or "0".

This digital signal is applied to the memory 12A, and is also applied to the exclusive OR game (13) as a comparison circuit.
Added to one end of A.

At the same time, the previous digital signal stored in the memory 12A is applied to the other end of the exclusive OR gate 13A.

Here, the comparison with exclusive or gate 13A is 1
This is done sequentially for each bit.

The output of exclusive OR gate 13A is then added to counter 14A.

Note that a start signal ST for starting reading and a clock pulse CL are applied to the one-dimensional light receiving diode array 1A, and a clock pulse CL is applied to the memory 12A.

On the other hand, 10
Identical circuits B through 14B are provided.

Then, the outputs of the counter 14A and the counter 14B are respectively applied to the arithmetic unit 15 which performs the arithmetic operation of the above-mentioned equation (4).

Here, the reason why the video signals of the one-dimensional light receiving diode arrays IA and IB are converted into digital signals is to configure the subsequent stage with a simple digital circuit, and the memory 12A,
12B stores the previous digital signal and compares it with the current digital signal to distinguish between the background of a monitoring point that does not change over time and an intruding object represented by a moving object that changes over time. It's for a reason.

Exclusive-OR gate circuits 13A and 13B are used to detect mismatch points (mismatch bits) between the previous signal and the current signal.
This is to detect.

The counters 14A and 14B count the number of mismatch points (number of mismatch bits) between the previous signal and the current signal, and this number is proportional to the size of the invading object.

When the start signal ST is applied to the one-dimensional light-receiving diode array 1A, the one-dimensional light-receiving diode array 1A sequentially transmits video signals corresponding to the exposure of the individual light-receiving diode elements constituting it according to the clock pulse CL.
Output each item one by one.

This output is amplified to a predetermined level by an amplifier 10A and then applied to a slicer 11A.

The slide f11A is applied to the memory 12A as a serial digital signal in which signals above a certain threshold level are expressed as logic "1" and signals below that level are expressed as logic "0".

Memory 12A temporarily stores the digital signal.

In this way, the state of the monitoring point at a certain time is "1".
” "0"... is stored as a digital signal.

Next, when the start signal ST is applied again to the one-dimensional light receiving diode array 1A, a memo indicating the status of the previous monitoring point! At the same time, the contents of J12A are read out in accordance with the clock signal CL and applied to the exclusive OR gate 13A, and at the same time, a signal indicating the status of the current monitoring point, which has been converted into a digital signal by the slicer 11A, is applied to the exclusive OR gate 13A. It is compared every time.

-If there is an invading object as shown in Figure 2, the previous signal and the current signal should change depending on the size of the object, so this exclusive or game) 13A detects the difference between the two signals (a point of mismatch), and by counting the number of mismatched bits using a counter 14A, it is possible to know the size of the one-dimensional light receiving diode array 1A of the invading object.

For example, if the pitch of the diode elements constituting the one-dimensional light receiving diode array 1A is 60 microns, and the count value of the counter 14A is 50, then 60×50
=3000 microns - 3 mm is the size a of the intruding object on the light receiving surface of the one-dimensional light receiving diode array 1A.

By the same operation, 1 is calculated from the count value of the counter 14B.
The size b of the intruding object on the light receiving surface of the dimensional light receiving diode array 1B can be determined.

The calculation device 15 receives the counted values of these counters 14A and 14B, calculates the sizes a and b of the intruding object on the light receiving surface, and further calculates the above equation (4) to determine the actual size of the intruding object. A signal SH indicating the level H is output.

Note that in Figure 2 above, a convex lens is used as the lens system to image the monitoring point on the dimensional light receiving diode array, but a combination lens such as a zoom lens may also be used, or a concave mirror may be used. obtain the effect of

According to the present invention, the monitoring distance is indefinite,
Even if the background of the monitoring point is complex, it is possible to know whether there is an intruding object and its size.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing a conventional intruding object detection device, FIG. 2 is a schematic diagram showing an optical device portion of an embodiment of the intrusion object detection device according to the present invention, and FIG. 3 is a schematic diagram showing a photoelectric conversion device portion of the embodiment. FIG. IA, IB・・・One-dimensional light receiving diode array,
2A, 2B-m-... Convex lens, 10A, IOB...
-...Amplifier, 11A, 11B...-Slicer, 12A. 12B...°...Memory, 13A, 13B...
・Exclusive or gate, 14A, 14B...
...Counter, 15...--Arithmetic device.

Claims (1)

[Claims] 1 Lens systems installed facing each other, a one-dimensional light-receiving diode array that receives images of monitoring points by these lens systems, a circuit that digitizes the output of these light-receiving diode arrays, and a digital Compares the memory that stores the converted signal with the digital signal that indicates the state of the previous monitoring point stored in the memory and the digital signal that indicates the current state, and outputs only when there is a difference between the two signals. A comparator circuit that counts the output of the comparator circuit, and a counter that counts the output of the comparator circuit, and receives the count value of each counter corresponding to the size of the intruding object on each one-dimensional light receiving diode array, and calculates the actual size of the intruding object. An intruding object detection device comprising: an arithmetic device for calculating.