JPH057676B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an object detection device, and particularly to an object detection device for detecting whether or not an object exists within a predetermined three-dimensional space.

Object detection devices include those that detect the presence or absence of an object using its physical properties, such as weight, size, and position, and those that detect the presence or absence of an object using its electrical or magnetic properties, that is, changes in the electric or magnetic field. Various methods have been used to date, including those that detect the presence of objects, and those that irradiate an object with a light beam, electron beam, ultrasonic beam, etc. and confirm the existence of the object by the presence or absence of reflected waves or transmitted waves. It is used.

In addition, as a non-contact detection method for objects, the appearance of the object is converted into a video signal using an imaging device, this video signal is displayed on a cathode ray tube, and an optical sensor is pasted on the cathode ray tube. BACKGROUND ART Conventionally, it has been considered to check the presence or absence of an object based on a change in brightness at the position of a sensor.

However, with this method of detecting the brightness on the cathode ray tube, it is necessary to mount an optical sensor on the display surface as necessary to detect the brightness on the display surface, and it is also difficult to compare the brightness on the cathode ray tube. There is a problem that there is a certain limit to miniaturizing the overall configuration because a cathode ray tube that is large in size must be prepared, and furthermore, depending on how the optical sensor is attached to the display surface, the sensor may be attached to an external device. There is a risk that light will be mixed in and noise will be included in the brightness detection results.

In addition, in the case of an object detection device that converts the appearance of an object into a video signal using an imaging device, the lighting performance of the lighting equipment used to image the object deteriorates over time. The installation position and orientation of the lighting equipment may change over time, or the brightness may change in response to changes in the ambient temperature (i.e., changes due to temperature characteristics may occur). If the video signal generation conditions in the imaging device change over time from the state set at the initial stage of detection, a drift may occur in the video signal based on the change in the video signal generation conditions. As a result, there is a possibility that the object detection device may make a false detection.

The present invention has been made in consideration of the above points, and
By electrically processing the video signal obtained by the imaging device, it is possible to confirm the presence or absence of an object without the need for complicated labor and to avoid the risk of false detection even if the video signal generation conditions change. This paper attempts to propose an object detection device that does the following.

As a means to solve such problems, the present invention
A video camera 7 that images the object to be detected and screen information obtained from the video signal VD sent from the video camera 7 are placed in monitoring areas A1 and A2 located at a predetermined monitoring position and having a predetermined size. A measurement result signal S6 is obtained by capturing a corresponding video signal at each predetermined sampling point and having a level corresponding to the instantaneous value of the captured video signal VD.
The measuring means 11, 26 outputs the measurement result signal S for each sampling point output from the measuring means 11, 26 in the past plural measurement cycles.
The signal level of the measurement result signal S6 obtained from the measurement means 11 and 26 is calculated by the reference value calculation means 27.
A comparison determination means 28 is provided to send out an object detection signal S20 depending on the presence or absence of an object by comparing it with a reference value obtained in .

According to such a configuration of the present invention, the measuring means 1
1 and 26 are video signals for each sampling point.
The measurement result signal S6 is sent from the VD, and the reference value calculation means 27 executes the reference value calculation processing and the comparison and judgment means 28 performs the judgment processing.By processing each sampling point in this way, it is possible to detect abnormalities. Immediately after determining the sampling point, it is possible to obtain a determination result indicating that the entire system is abnormal, which has good responsiveness.Furthermore, since it is possible to determine abnormality in detail down to the sampling point on the screen, it is possible to obtain a highly accurate determination result. An object detection device that can obtain the following can be easily realized.

In addition, according to the configuration of the present invention, the reference value calculation means 27 calculates the reference value based on the measurement result signal S6 output from the measurement means 11 and 26 in the past plural measurement cycles, and as a result, the Even if the video signal generation conditions such as illumination change with the passage of time and the effect thereof appears on the measurement result signal S6, this effect can be canceled out by the effect that appears on the reference value at the time of comparison judgment in the comparison judgment means 28. can.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the drawings as an embodiment in which the present invention is applied to detecting whether or not a product injection-molded in an injection molding machine is knocked out of a mold.

In FIG. 1, an injection molded product as an object to be detected by an injection molding machine 1 is molded by injecting molding material through a conduit 4 with a movable side mold 2 in pressure contact with a fixed side mold 3. After moving back and away from the fixed side mold 3 to the side mold 2 along the guide 5,
Ejection pin provided on movable side mold 2 (not shown)
It is designed to be pushed down below the injection molding machine 1.

However, if the movable mold 2 retreats in this way and the product should fall, but the product does not fall completely and ends up adhering to the movable mold 2 or the fixed mold 3, the next injection Since the product is caught between the movable mold 2 and the fixed mold 3 during the molding cycle, there is a risk that the molds 2 and 3 will be damaged.
In order to prevent such a possibility, an object detection device 6 is provided.

The object detection device 6 includes a video camera 7 and an object detection circuit 8. The video camera 7 is disposed at a position near the movable mold 2 on the side of the injection molding machine 1, and images the scene near the movable mold 2 at the timing when the movable mold 2 has finished opening from the fixed mold 3. The video signal VD is sent to the object detection circuit 8.

The injection molding machine 1 is sequentially controlled by a sequencer (not shown), and therefore the sequencer sends timing command signals as necessary at timings such as when the mold starts to open, when it finishes opening, and when the ejector pin moves to eject. S1 is generated and given to the object detection circuit 8.

In the case of this embodiment, the video signal VD capturing the state in which the product is still attached to the movable mold 2 at the timing when the movable mold 2 has finished opening can be taken into the object detection circuit 8, and the The video signal VD captured at the timing when the object is pushed down by the ejector pin can be taken into the object detection circuit 8.

As shown in FIG. 2, the object detection circuit 8 receives a standard television video signal including horizontal and vertical synchronization signals sent from the video camera 7.
It has a hold device 11 that receives VD, and a synchronization signal generator 12 that receives the synchronization signal SY as a trigger signal. Synchronous signal generator 12
A synchronizing signal CL for synchronizing the operation in the object detection circuit 8 with the video camera 7 is generated in synchronization with the synchronizing signal SY.

The hold device 11 captures the luminance signals of monitoring areas at a plurality of predetermined positions on the screen formed by the video signal VD. In this embodiment, the monitoring areas A1 and A2 are arranged as shown in FIG. If we take the x coordinate in the H direction and the y coordinate in the V direction, we get the point (x ₁ , y ₁ ), the point (x ₁ +m,
y ₁ ), point (x ₁ , y ₁ +n) and point (x ₁ +m, y ₁ +n)
It is an area surrounded by four points, and the monitoring area A2
are points (x ₂ , y ₂ ), points (x ₂ + m, y ₂ ), points (x ₂ , y ₂ +
n), and the point (x ₂ +m, y ₂ +n).

As shown in FIG. 4, the hold device 11 includes first and second analog switch circuits 18A and 1 which receive the video signal VD through a buffer circuit 15.
8B (corresponding to the first and second monitoring areas A1 and A2), the data acquisition switch circuit 18 receives the acquisition command generated by the timing generator 25. It is turned on by signal S3I.

That is, as shown in FIG. 5, the timing generator 25 monitors the first, second,...th scanning line starting from the start time _t0 of the vertical synchronization signal V (FIG. 5A). Regarding the scanning line that crosses the areas A1 and A2, the monitoring areas A1 and A2 are
A capture command signal S3I is generated at a timing corresponding to 2.

In the case of the embodiment of FIG. 3, the monitoring area A1 is horizontally synchronized for the y _- th line (By ₁ in FIG. 5) to the (y ₁ +n)-th line (B(y ₁ +n) in FIG. 5). A switch signal is sent to the analog switch circuit 18A when a time corresponding to the coordinate x in the x-axis direction has elapsed from the start of the signals Hy ₁ to H (y ₁ +n).
SW1 is activated for a time corresponding to the distance m in the x-axis direction of the monitoring area A1.

Also, regarding the monitoring area A2, the y _- th line ~
The (y ₂ +n)th line (Fig. 5 By ₂ ~ B (y ₂
+n) for each horizontal synchronization signal Hy ₂
~ Monitoring area A2 from the rising point of H(y ₂ +n)
When a timing corresponding to the coordinate x ₂ has elapsed, the switch signal SW2 to the analog switch circuit 18B is raised for a time corresponding to the distance m in the x-axis direction of the area A2.

Thus, in FIG. 3, for one field of video signal, the analog switch circuits 18A and 18B are turned on at the timing when the scanning line crosses the monitoring areas A1 and A2, respectively, so that the light at each pixel position in the monitoring areas A1 and A2 is turned on. A video signal having an instantaneous value corresponding to the energy is sent to detection signals S2A and S through analog switch circuits 18A and 18B for each corresponding line.
2B, and these detection signals S2A and S2B are given to the analog-to-digital converter 26 as an input video signal S4.

The analog-to-digital converter 26 converts the digital data into digital data in response to the sampling clock signal S5 sent from the timing generator 25, and provides this to the reference value calculation device 27 and the comparison/judgment device 28 as measurement result data S6.

The reference value calculation device 27 uses the measurement result data S currently obtained from the analog-to-digital conversion device 26.
6, the movable side mold 2 in the injection molding machine 1
And whether or not there is any product left between the fixed side molds 3,
The judgment reference value data is calculated so that a judgment can be made based on the past measurement result data, and for example, the configuration shown in FIG. 6 can be applied.

In FIG. 6, the reference value calculation device 27 performs arithmetic processing on the measurement result data S6 sent from the analog-to-digital conversion device 26 based on the timing control signal S8 given from the timing generation device 25. That is, the measurement result data S6 is given to the first stage memory M1 of a plurality of continuously connected memories M1, M2, . . . Measurement result data S6 arriving in a cycle is sequentially stored in memories M1, M2 . . . Mk.

Here, the memories M1, M2...Mk have a memory capacity capable of storing sampling data groups corresponding to sampling points included in the monitoring area A1,
In this way, each time one injection molding cycle is completed, the sampling data group is sequentially transferred to the subsequent memory.

The sampling data stored in the memories M1 to Mk are given to the adder AD1 for each sampling point, and the addition result data S
9 is the output of the observation data memory 31 and the divider 3
given to 2. In this way, the adder AD1 outputs addition result data S9 obtained by performing an addition operation on each sampling data included in the monitoring area A1.

A constant signal S10 corresponding to the number k of addition data in the observation data memory 31 is given to the divider 32 from the constant setter 30, and thus each sampled addition data constituting the addition result data S9 is sent to the divider 32 as a constant signal. Average value data S11, which is simple average data obtained by dividing by S10, is obtained.

This average value data S11 is given to an upper limit value circuit 33 and a lower limit value circuit 34 having a multiplier configuration, and multiplication outputs S14A and S15A are obtained by multiplying constant signals S12 and S13 given from constant setters 35 and 36, respectively. are sent out as an upper limit reference signal S14 and a lower limit reference signal S15, respectively.

Here, a constant signal S given to the upper limit circuit 33
The contents of 12 are set to R _H (R _H >1), and
Constant setting signal S13 given to lower limit value circuit 34
The content of is set to R _L (R _L <1). In this way, the upper limit reference signal S14, which is larger than the average value of the past k measurement result data, is sent from the upper limit value circuit 33 for each sampling point, and the lower limit value circuit 3
A lower limit reference signal S15 smaller than the average value of the measurement data of the past k times from 4 to 4 is sent out for each sampling point.

These reference signals S14 and S15 are given to a comparison/judgment device 28 and compared with the measurement result data S6 sent from the analog-to-digital conversion device 26 for each sampling point, and the measurement result data S
6 is smaller than the upper limit reference signal S14 and larger than the lower limit reference signal S15, it indicates that the product has fallen normally from the injection molding machine 1 and there is no product between the movable mold 2 and the fixed mold 3. An object detection output signal S20 is sent out.

On the other hand, if the measurement result data S6 is larger than the upper limit reference signal S14, it means that the brightness between the movable mold 2 and the fixed mold 3 is brighter than when the product is dropped. Indicates that a product is present (if its outer surface is fairly bright).

On the other hand, if the measurement result data S6 is smaller than the lower limit reference signal S15, the brightness between the movable side mold 2 and the fixed side mold 3 is lower than when there is no product, in other words, there is a product. (In this case, the outer surface of the product is quite dark.) In this way, it is possible to obtain an object detection signal S20 indicating whether or not the product is present between the movable mold 2 and the fixed mold 3 at the timing when the injection molding machine 1 opens the mold and drops the product using the ejector pin. .

Reference value calculation circuit 27B for monitoring area A2
has the same configuration as the reference value calculation circuit 27A, and thus sends the output signals S14B and S15B for each sampling point included in the monitoring area A2 to the comparison/judgment device 28 as the upper limit reference signal S14 and the lower limit reference signal S15. Accordingly, it is possible to obtain an object detection signal S20 for each sampling point included in the monitoring area A2.

In the above configuration, after the injection molding machine 1 opens the movable mold 2 and pushes out the product with the ejector pin, the timing generator 25 is removed by the timing command signal S1 given from the sequencer to the object detection circuit 8. A hold command signal S3I is sent to the hold device 11.

That is, regarding the monitoring area A1, the analog switch circuit 18A of the hold device 11 is
By ₁ , B (y ₁ + n), ... As shown in B (y ₁ + n), after the time corresponding to the coordinate x ₁ in the x direction of the left end of the monitoring area A1 has elapsed from the vertical synchronization signal V, Switch signal given as input command signal S3I
Turns on by SW1.

Therefore, when the video signal VD is taken into the hold device 11 while the analog switch circuit 18A is on, it is sampled at the sampling frequency in the analog-to-digital converter 26 and sent to the comparison/judgment device 28 and the reference value calculation device 27. Sent out.

Here, the reference value calculation device 27 stores data representing the instantaneous value of each sampling point of the past k times by writing the given measurement result data S6 into the first stage memory M1 for each sampling point. , by supplying this as the output data K1 to Kk to the average value calculation means consisting of the adder AD1 and the divider 32, the upper limit based on the average value of the data of each instantaneous value obtained in the past k injection molding cycles. Value and lower limit reference signals S14A and S15
A is supplied to the comparison/judgment device 28.

Therefore, the comparison and determination device 28 compares and determines the measurement result data S6 provided from the analog-to-digital conversion device 26 for each sampling point using the average value of the detection data obtained in the past k injection molding cycles.

If the surface of the product is bright, injection molding machine 1
When the ejector pin operates normally and the product is pushed down correctly by the ejector pin, the level of the measurement result data S6 is equal to the upper limit reference signal S14 and the lower limit reference signal S obtained in the reference value calculation device 27 (FIG. 6).
15, so the comparative judgment device 28
sends out an object detection signal S20 indicating that there is no object.

On the other hand, if the product is not ejected from the movable mold 2 even though the injection molding machine 1 operates the ejector pin, the level of the detection signal S6 will be low because the surface of the product is quite bright. It becomes larger than the upper limit reference signal S14 obtained by the reference value calculation device 27. Therefore, at this time, the comparison and determination device 28 sends out an object detection signal S20 indicating that an object is present.

In the above case, the brightness of the product's surface is bright, but conversely, if the product's surface is darker than when there is no product (for example, if the product's surface is black), the measurement result will be The level of the data S6 becomes extremely low and becomes lower than the lower limit reference signal S15 obtained by the reference value calculation device 27.
In this case as well, the comparison/judgment device 28 will send out the object detection signal S20 indicating that the product has not been pushed out of the injection molding machine 1.

According to the above configuration, the presence or absence of an object can be determined by signal processing the video signal VD obtained from the video camera,
In this way, by obtaining the measurement result data S6 based on instantaneous values, it is possible to determine the presence or absence of an object in each monitoring area A1 and A2 in a short time, resulting in even better responsiveness and higher determination accuracy. It is possible to realize an object detection device with high performance.

Incidentally, if an abnormality occurs in some of the plurality of monitoring areas A1 and A2 during repeated injection molding cycles, the signal corresponding to the monitoring area A1 or A2 where the abnormality has occurred is captured as the video signal VD. An abnormality determination output can be obtained immediately when this abnormality signal is sampled (without waiting for a detection operation for the entire monitoring area), and thus a determination output with better responsiveness can be obtained. In addition, by being able to obtain an abnormality determination output for each sampling point, it is possible to determine abnormalities with high precision even in the smallest details on the screen.

Moreover, by using a signal representing the average value based on the detection signals obtained in the past k injection molding cycles as the upper limit value and lower limit reference signals S14 and S15, the video camera 7 can detect the injection molding machine 1. If the imaging conditions change midway (for example, if the level of the video signal VD drifts due to deterioration of the light source, temperature characteristics, etc.), the influence will be reflected in the judgment result data S6.
This can be compensated by simultaneously occurring in the reference signals S14 and S15, and thus the influence of fluctuations in imaging conditions on the determination result can be further reduced.

In the case of the embodiment shown in FIG. 2, the timing generator 2
5 is a capture command signal S to the hold device 11.
In order to generate 3I, a take-in signal generating circuit 41 having the configuration shown in FIG. 7 is provided.

In FIG. 7, the acquisition signal generation circuit 41 is a RAM
The monitoring position designation memory 42 has a monitoring position designation memory 42 configured such that data regarding the scanning positions of the monitoring areas A1 and A2 described above with reference to FIG. It is designed to be written as a data signal DP.

For example, as shown in FIGS. 8 and 9, the monitoring areas A1 and A2 described above with respect to FIG. 3 have a length of 4 scan lines in the V direction and 5 scan lines in the H direction.
If an area having a length corresponding to two sampling points is to be monitored, the monitoring position designation memory 42 stores the monitoring area A as shown in FIG.
Regarding line number data y ₁ to (y ₁ +3), data containing x-direction position data x ₁ and data acquisition switch circuit designation data 18A are stored for line number data y 1 to (y 1 +3), and line number data is stored for monitoring area A2. For y ₂ to (y ₂ +3), x-direction position data x ₂ and data acquisition switch circuit designation data 18B are stored as data.

Each line number data y ₁ ~ (y ₁ + 3), y ₂ ~ (y ₂
+3) is assigned to a predetermined memory area of the monitoring position designation memory 42, and by reading the address of the memory area, the x-direction position data and data acquisition switch circuit designation corresponding to the line number data assigned to this are assigned. Data is read.

The count contents of the y counter 43 are given to the monitoring position designation memory 42 as a read signal through an address converter 44. The y counter 43 counts clock pulses CLH provided from the synchronizing signal generating circuit 12 (FIG. 2) in synchronization with the horizontal synchronizing signal H. In this way, the contents of the y counter 43 sequentially designate the scanning line numbers of the video signal. When the y counter 43 operates, its contents are y ₁ to (y ₁ +3) or y ₂
.about.(y ₂ +3), data regarding the corresponding line number data is read out to the x-direction position register 45 and the data acquisition switch circuit designation register 46. The contents of the x-direction position register 45 are given to a comparator 47 and monitored to see if they match the contents of the x counter 48. x counter 4
8 is designed to sequentially designate the number of monitoring points in the x direction, for example, the synchronization signal generator 12 (second
A clock signal CLX having a period similar to that obtained by dividing the horizontal synchronizing signal obtained from FIG.

When the position is detected by the comparator 47 in this way, the position detection output PS is given as a trigger signal to the pulse generation circuit 49 having a mono-multivibrator configuration, for example, so that a pulse with a predetermined pulse width is sent to the acquisition signal generation circuit having a decoder configuration. 5
0 as a load signal. The acquisition signal generation circuit 50 converts the data acquisition switch circuit designation data stored in the data acquisition switch circuit designation register 46 into a switch signal SW1 or
Convert to SW2, this is analog switch circuit 1
It is sent as a capture command signal S3I for 8A and 18B (FIG. 4).

According to the configuration shown in FIG. 7, the monitoring position designation memory 4
2, as shown in FIGS. 8, 9, and 10, stores the x-direction position data of the left end of the monitoring areas A1 and A2 together with the corresponding data acquisition switch circuit designation data, Thus, if the video signal VD reaches a section corresponding to a scanning line that crosses the left end of the monitoring position A1 or A2,
In accordance with the contents of the y counter 43 at this time, the x-direction position data and the data acquisition switch circuit designation data of the monitoring position designation memory 42 are read out to the x-direction position register 45 and the data acquisition switch circuit designation register 46. , At the same time, the contents of the x counter 48 for the relevant scanning line are counted so that the relevant scanning line is sequentially scanned from the left side to the right side.

When the contents of the x counter 48 eventually match the contents read out to the x direction position register 45, this means that the monitoring area A1 of the video signal
This means that the video signal corresponding to the left end of A2 has arrived. At this time, the comparator 47 generates the position detection output PS, so the acquisition signal generation circuit 5
0 is the data capture switch circuit designation register 46
Switch signals SW1 and SW2 corresponding to the contents of
is sent to analog switch circuits 18A and 18B.

Here, since the pulse width of the pulse generation circuit 49 is selected to have a length corresponding to the length of the monitoring areas A1 and A2 in the x direction, the acquisition command signal S3I output from the acquisition signal generation circuit 50 is generated. The time exactly coincides with the time when monitoring areas A1 and A2 are being scanned.

Therefore, as described above with respect to FIGS. 8 and 9, switch signals SW1 and SW2 are obtained for the four scan lines across the monitoring areas A1 and A2, thereby providing monitoring signals from the analog switch circuits 18A and 18B. Area A1 and A2
The instantaneous values of the video signal VD corresponding to are sequentially taken into the hold device 11.

Incidentally, it is only necessary to store data regarding the start position of the monitoring area in the monitoring position designation memory 42, and therefore, even if the number of monitoring areas increases, the storage capacity of the memory 42 does not need to be increased that much. Also good. In addition, when specifying the monitoring position or changing the area of the monitoring area, the monitoring position specification memory 42
It is only necessary to change the stored data, and thus a highly versatile object detection device can be realized.

In addition, in the case of FIGS. 8 and 9, the monitoring area A1
and A2 are not overlapped on the same scanning line, but in the case where multiple monitoring areas are set to overlap on the same scanning line,
As shown by the broken line in FIG. 7, by inputting the count contents of the x counter 48 to the address converter 44 and thereby specifying the position in the x and y directions, the corresponding x direction position data and data What is necessary is to specify the data for specifying the switch circuit for taking in.

Also, in the comparator 47, the x counter 48
In addition to the contents of , the contents of the y counter 43 may be given as a comparison input as necessary.

Further, the number of monitoring areas is not limited to two as in the above embodiment, but can be three or more, or can be one.

Furthermore, in the above description, when monitoring the screen of the video signal VD obtained by the video camera 7, V
We have described a case in which a monitoring area with a width of multiple scanning lines is specified in the direction, but instead of this, as shown in FIG. It is also possible to monitor only for a certain period of time. In this case, in FIG. 10, for example, the x-direction position data and the data acquisition switch circuit designation data for only one scanning line (in the case of FIG. 10, there are multiple lines) are stored as data for the monitoring area designation position. Just try to remember it.

Thus, in the same manner as described above for the monitoring areas A1 and A2, a determination result can be easily obtained using the detection output representing the optical energy of the monitoring areas.

Further on-screen monitoring of the video signal VD
As shown in the figure, even if a specific point is specified, the presence or absence of an object can be detected in the same manner as in the above case.

FIG. 13 shows another embodiment of the reference value calculation device 27, and as shown by assigning the same reference numerals to the corresponding parts as in FIG. 6, when calculating the reference value, the case shown in FIG. has an observation data memory 31 and a division circuit 32 for obtaining a reference value at a timing after the movable mold 2 of the injection molding machine 1 is opened and the product is pushed down by the ejector pin. In addition to this, the case shown in FIG. 13 is characterized in that the reference value is calculated at a timing before the product is pushed down by the ejector pin.

That is, the reference value calculation device 27 in the case of FIG.
has a pre-observation data memory 55 having the same configuration as the observation data memory 31, a divider 56 similar to the divider 32, and a constant setter 57 similar to the constant setter 30.

Here, the measurement result data S6 is input to the observation data memory 31 and the pre-observation data memory 55 as follows.
This is done via a changeover switch circuit 58. This changeover switch circuit 58 is controlled by a changeover control signal S21 given from the sequencer of the injection molding machine 1, and after the injection molding machine 1 has finished opening the movable mold 2, the switch circuit 58 is switched to the front observation Switch to the data memory 55 side and measure result data S.
6 is input to the front observation data memory 55 side through the switch circuit 58, and the measurement result data S6 is input to the observation data memory 31 at the timing after the ejecting operation is performed and the product is pushed down. ing.

In this way, the reference value calculation device 27 stores observation data before and after the ejection operation of the ejector pin in the observation data memory 31 and the pre-observation data memory 55, calculates the simple average value using the dividers 32 and 56, and calculates the simple average value. The results are simply averaged in an adder 60 and a divider 61, and then sent to the comparison/judgment device 28 as a reference value signal S25.

In addition to this, the reference calculation device 27 includes a divider 3
The outputs of 2 and 56 are applied to a comparator 62, and the comparator 62 detects a change between the calculated data before the ejecting operation of the injection molding machine 1 and the calculated data after the ejected operation, and outputs the output as a reference value signal S26 to the comparison/judgment device 28. In the configuration shown in FIG. 13, the reference value calculation device 27
The observation data before and after the ejection operation of the injection molding machine 1 can be stored in the observation data memory 31 and the pre-observation data memory 55, respectively. Here, the data stored in the pre-observation data memory 55 before the ejection operation means that the data is obtained when the product injection molded by the injection molding machine 1 still remains on the movable mold 2. Therefore, the data represents the brightness of the outer surface of the product. On the other hand, the data stored in the observation data memory 31 after ejection means that the product is ejected from the injection molding machine 1. Therefore, if the injection molding machine 1 is operating normally, The data in the observation data memory 31 represents the brightness of the injection molding machine 1 when there is no product.

Therefore, the reference value signal S25 obtained by the simple average calculation in the divider 61 represents the intermediate value between when there is a product in the injection molding machine 1 and when there is no product in the injection molding machine 1. It is possible to clearly determine whether or not there is a product based on the given measurement result data S6 with certainty around the reference value S25 by determining whether or not it exceeds the reference value S25.

In this way, the reference value S25 is configured to include a drift in the video signal VD due to a light source, a video camera, etc., to form a reference value, so that the comparison/determination device 28 can make a better judgment. This means that these drifts can be canceled during operation. Therefore, the object detection signal S22 can be made free from the influence of drift.

In addition, since the comparator 62 compares the measured data when the product is present and the measured data when there is no product, it can be determined whether the product is present or not, regardless of whether the surface color of the product is black or white. can be determined with certainty.

Incidentally, if the product is black, the level of observation data when the product is present will be low, whereas if the product falls and disappears, it means that there is no black object, so the level of observation data when the product is not present will be lower. The level will be higher than the level of observation data if it exists. Therefore, if there is a change in the level of the signal arriving at the comparator 62, the injection molding machine 1 can send out the reference value signal S26 that reliably indicates that there is no product due to the ejecting operation of the ejecting pin. Become. Conversely, if the product is white, the level of observation data when there is a product is higher than the level of observation data when there is no product, so in this case as well, the comparator 62
It can be reliably determined that the product is not in the injection molding machine 1 based on the difference between the two signals arriving at the injection molding machine 1. Also in this case, it is possible to prevent the influence of drift from occurring on the determination result in the comparison and determination device 28.

FIG. 14 shows still another embodiment of the reference value calculation device 27, and in FIGS. 6 and 13, the configurations of the observation data memory 31 and the pre-observation data memory 55 are replaced by the observation data memory in FIG. 14. 6
Replace with 5.

The observation data memory 65 inputs the outputs of the memories M1, M2, . . .
1, W2... Multipliers PL1, PL2... that multiply the weighted outputs w ₁ , w ₂ ... w _k of Wk as coefficient inputs.
The signal is supplied to the adder AD1 through PLk.

If configured as shown in Fig. 14, reference data will be obtained based on detection data for the past k injection molding cycles, and each data will be weighted according to its importance, making it optimal as a reference value. data can be obtained. For example, injection molding machine 1
In cases where the background brightness changes over time, newer observation data is considered to be the most effective data, so the weight setting value w ₁ ,
By setting w ₂ ... w _k in the relationship w ₁ > w ₂ ... > w _k , it is possible to prevent errors due to changes in background brightness from appearing in the judgment results of the comparison judgment device 28. It will be possible.

In the embodiment shown in FIG. 2, the detection data taken in by the hold device 11 is converted into a digital value by the analog-to-digital converter 26, and then digitally compared and determined by the comparison and determination device 28. But instead of this,
As shown in FIG. 15, the detection signal captured by the hold device 11 is directly compared and determined by the
The comparison/determination device 28 may determine the presence or absence of an object in an analog manner. In this case, the detection output S4 taken in from the hold device 11 is converted into a digital signal by the analog-to-digital converter 71 and given to the reference value calculation device 27 as measurement result data, and the result of arithmetic processing in the reference value calculation device 27 is The obtained reference value signal is converted into an analog signal in the digital-to-analog converter 72 and then provided to the comparison/judgment device 28 .

Even in this case, the same effect as described above with respect to FIG. 2 can be obtained.

In addition, instead of the configuration shown in FIG. 2, as shown in FIG. 16, after the video signal VD is taken in as a hold device 11 via a data take-in switch circuit 18, it is converted into digital data in an analog-to-digital converter 74. After conversion, it is temporarily stored in the digital memory 75, and the digital memory 7
The digital data stored in 5 may be sent to the reference value calculation device 27 and the comparison/judgment device 28 as measurement result data S6.

Even in this case, the instantaneous values of the sampling points included in the monitoring areas A1 and A2 can be stored in the digital memory 75 as digital data, so that the same effect as in the case of FIG. 2 can be obtained.

Further, in the above embodiment, the video camera 7 provides the synchronization signal to the synchronization signal generator 12, but instead of this, the video camera 7 is synchronized with the synchronization signal generated by the synchronization signal generator 12. You may also do this.

Further, in the above-described embodiment, the present invention was described as an embodiment in which the present invention was applied to detect whether or not a product fell off when a mold in an injection molding machine was opened. It can also be widely applied to security devices that detect objects placed on a conveyor or that detect intruders entering a predetermined space.

As described above, according to the present invention, the response when obtaining the judgment result is improved by obtaining the judgment result using the reference value calculated for each predetermined sampling point for the video signal corresponding to the predetermined monitoring area. Moreover, the occurrence of abnormalities can be determined with high accuracy even in the smallest details on the screen.

Further, according to the present invention, the determination reference value is calculated based on the measurement results of a plurality of past measurement cycles, so that the level of the measurement output may shift, for example, due to a change in the video signal generation conditions. Even when a disturbance such as electrical noise occurs, it is possible to realize a determination result that is not affected by such disturbance.

[Brief explanation of the drawing]

FIG. 1 is a schematic perspective view showing an overview of the object detection device according to the present invention, FIG. 2 is a block diagram showing the detailed configuration of the object detection circuit, and FIG. 3 is a schematic diagram for explaining the monitoring area. FIG. 4 is a connection diagram showing the detailed configuration of the hold device in FIG. 2, FIG. 5 is a signal waveform diagram representing the take-in signal given to the hold device 11 from the timing generator 25 in FIG. 2, and FIG. FIG. 2 is a block diagram showing a specific configuration of the reference value calculation device 27, FIG. 7 is a block diagram showing a detailed configuration of the acquisition signal generation circuit 41 included in the timing generation device 25 of FIG. ~Figure 10 is a schematic diagram and chart for explaining the configuration of Figure 7, Figures 11 and 12 are schematic diagrams showing other embodiments of the monitoring position, and Figure 13 is the standard of Figure 2. FIG. 14 is a block diagram showing still another embodiment of the reference value calculation device 27 shown in FIG. 2, and FIGS. FIG. 7 is a block diagram showing still another embodiment. 1... Injection molding machine, 2, 3... Movable side, fixed side mold, 7... Video camera, 8... Object detection circuit,
DESCRIPTION OF SYMBOLS 11... Hold device, 12... Synchronization signal generator, 25... Timing generator, 26... Analog-to-digital conversion device, 27... Reference value calculation device, 28... Comparison/judgment device, 41... Capture signal generation circuit.

Claims (1)

[Claims] 1. (a) a video camera that images an object to be detected; (b) a predetermined range in the horizontal and vertical directions with respect to screen information obtained by a video signal sent from the video camera; A monitoring area having a predetermined size is set by specifying the monitoring area, and in sequentially repeated measurement cycles, measurement is performed such that each sampling point included in the monitoring area has a signal level corresponding to the instantaneous value of the video signal. (c) measuring means for outputting a result signal as measurement information including change information representing a disturbance and representing the brightness of the sampling point; A reference value is calculated from the level of the measurement result signal output from the measurement means for each sampling point, and the reference value is used as reference value information including change information representing disturbances during the plurality of past measurement cycles. , a reference value calculation means for outputting, (d) comparing the signal level of the measurement result signal obtained from the measurement means with the reference value obtained in the reference value calculation means, and determining the disturbance contained in the measurement result signal; and a comparison and determination means for canceling the change information representing the disturbance included in the reference value by the change information representing the disturbance included in the reference value and transmitting a comparison result representing the presence or absence of an object as an object detection signal. Object detection device.