GB2041199A - Object inspection system - Google Patents

Abstract

In an object recognition or inspection system an object (2, Fig. 1) to be inspected is photoimaged by a photo image sensing device 4 (a T.V. camera). A synchronous separator circuit 11 separates out a horizontal synchronous signal h, a vertical synchronous signal v and a video signal s from the output of the image sensing device 4. A comparative control signal cst is formed by processing the horizontal h as well as vertical synchronizing signals v by means of turning control circuits 12, 13 and a strobe circuit 14. The video signals and a reference signal from a reference signal generator 15, are supplied to a comparator 16, which compares these input signals during the period specified by the comparative control signal cst. An inspection start signal is generated by the comparator when an object is detected and is supplied to a multivibrator 17 connected to an inspection system to start the inspection of the object. <IMAGE>

Description

SPECIFICATION Object inspection system The present invention relates generally to an object inspection systems, and more particularly to a new object inspection system of the type that takes the photo image of an object to be inspected by a photo image sensing device.

Inspection systems for very small objects that are transferred by such means as belt conveyers under the prior art normally con duct inspection by microscopic magnification of the inspected object, but when the inspected object is very small, it is difficult to accurately detect whether or not the inspected object is transferred to a predetermined detecting position with high precision. Under the prior art, the arrival of the inspected object to the predetermined detecting position is detected by a photo switch, proximity switch, etc., but when the inspected object is very small, there are various points of inconvenience.

In order to overcome such status, inspected object position detection systems are already proposed where photo sensors are installed on the monitor screen on which inspected objects are projected. Such systems will be now explained in reference to Fig. 1. In the system under the prior art shown on Fig. 1, 1 is a belt on which an object 2 to be inspected is transferred in the direction indicated by an arrow 3. At a predetermined position in connection with belt, a photo image sensing equipment such as a television camera or the like 4 which photo magnifies the inspected object 2 partially is installed. 5 is a monitor screen of the photo image sensing system 4 on which, at a predetermined position, a photo sensor 6 in order to detect the positioning of the inspected object 2 is installed.In Fig. 1, the hatched block is an image 7 of the inspected object 2 on the belt 1 that is projected on the black background monitor screen 5, which object 2 moves on the monitor screen 5 in the direction indicated by arrow 8 towards sensor 6. When this image 7, for instance, laps over with sensor 6, this sensor 6 functions and generates a start signal which is supplied to an object inspection or recognition system 9 such as a computer or the like to conduct the specified inspection for the object 2. However, according to the shape and dimensions of the inspected object 2 or the position thereof on belt 1, for instance, when the image 7 of the inspected object 2 as shown on Fig. 1, is as the broken like block 10 and moves in the arrow direction 8 on monitor screen 5, this image 10 does not lap over with sensor 6.Therefore, in this case the inspection system 9 does not start its inspection operation and hence the inspection of the object 2 is not conducted. In order to avoid such status, even though the sensor 6 is installed with due considerations to the scan direction of the television camera 4 and the transfer direction of the inspected object 2, it is possible that the same type of inspection disability occurs.

Further, from the functional standpoint of television camera 4, since the position detection of the inspected object 2 shall be at intervals of 16.7 miliseconds, the positioning detection shall inevitably vary or scatter within 1 6.7 miliseconds.

It is further noted that non action also occurs with the trouble of the monitor television receiver, or upon the decrease of brightness thereof, with the addition that the monitor television receiver is constantly in motion so that the defect of shortened life thereof also occurs.

The present invention seeks to provide an object recognition system, which avoids the above mentioned defects of the systems of the prior art, and to provide an object recognition system which can positively inspect an object in a short time.

According to an aspect of the present invention, an object inspection system is provided which comprises: (a) a photo image sensing device picking up an object to be inspected and delivering a complex video signal; (b) means for separating horizontal and vertical synchronizing signals and a video signal from the complex video signal; (c) means for producing a comparative control signal based upon the horizontal and vertical synchronizing signals; (d) means for generating a reference signal; (e) means for comparing the video signal with the reference signal only within a period determined by the comparative control signal and producing an inspection start signal; and (f) means for inspecting the object when the inspection start signal is supplied thereto.

The other objects, features and advantages of the present invention will become apparent from the following description of an exemplary embodiment taken in conjunction with some of the accompanying drawings, in which drawings Figure 1 is a schematic diagram showing an object recognition system under the prior art; Figure 2 is a block diagram showing an example of the object recognition system according to the present invention; Figures 3A, 3B and 3C are schematic diagrams used to explain the present invention; and Figures 4A and 4B, Figs. 5A and 5B and Figs. 6A and 6B are waveform diagrams used to explain the present invention.

An embodiment of the present invention will hereinafter be explained in reference with Figs. 2 through 6.

Fig. 2 is a block diagram showing an exam ple of the object recognition system according to the present invention. On Fig. 2, 11 desig nates a synchronous separator circuit, which separates the complex video signal input from the television camera or the like of the photo image sensing system 4 which photographs an object to be inspected (not shown on the Fig. 2), into a horizontal synchronizing signal h, a vertical synchronizing signal v and a video signal s, respectively. The vertical synchronizing signal v that is separated by the synchronous separator circuit 11 is supplied to a timing control circuit 1 2. Then a strobe signal stv is made at the timing control circuit 1 2 based upon the vertical synchronizing signal v.This strobe signal stv which specifies the vertical position of the detection area on the monitor screen of a monitor television receiver as later explained, is supplied to a strobe circuit 14. On the other hand, the horizontal synchronizing signal h is supplied to a timing control circuit 1 3 and then the timing control circuit 1 3 makes a strobe signal sth based upon the horizontal synchronizing signal h. This strobe signal sth specifies the horizontal position of the detection area on the monitor screen as later described. This strobe signal sth is supplied to the strobe circuit 14. At this strobe circuit 14, by combining the strobe signals stv and sth respectively, a composite strobe signal or a comparative control signal cst is made.Accordingly, this comparative control signal cst specifies the horizontal as well as vertical position of the detection area on the monitor screen. This comparative control signal cst is supplied to a comparator 1 6. At the comparator 16, only during the period as specified by the composite strobe signal cst, in other words, only at the specified position on the monitor screen, the video signal s is compared with a reference signal of the brightness level on the monitor screen provided from a level control or reference signal generator 1 5. The comparator 1 6 is supplied to a mono-multi vibrator circuit 1 7 which includes a retriggerable mono-multi vibrator having a time width of, for instance, 63 microseconds minimum, and when there is an input the vibrator circuit 1 7 generates an inspection start signal sta. And this inspection start signal sta is supplied to an inspection system 1 8 for inspecting the object such as a computer as well known, although it is not shown on Fig. 2, inspection of the object is conducted. This inspection of the object can be monitored on a monitor screen 1 9 of a monitor television receiver 1 9M which receives the output video signal from the television camera 4.

According to the above described construction of the object recognition or inspection system according to the present invention, the following inspection of the object is carried out. In this case, it be assumed that if the monitor screen 1 9 is a black background, for instance, and an object 21 to be inspected is white based in Fig. 3A.When an object 21 to be inspected arrives at a detection area 20 whose position is specified on the monitor screen 1 9 by the comparative control signal cst, the comparator 1 6 outputs a compared output by which the mono-multi vibrator cir cuit 1 7 generates the start signal sta, and the inspection of the object 21 to be inspected is conducted at the inspection system 1 8.

Further, in order to establish the detection area 20 as indicated on Fig. 3A, it is suffici ent that the timing control circuit 1 2 so func tions that the output signal from the timing control circuit 1 2 by the vertical synchronizing signal v shall be arranged as indicated on Fig.

4A and the timing control circuit 1 3 so func tions that the output signal sth from the timing control circuit 1 3 by the horizontal synchronizing signal h shall be arranged as per Fig. 4B. By the present invention as above described, it is not necessary to provide a special photo optical sensor on the monitor screen 1 9 as in the case with the prior art, and since the detection area 20 is specified as a free determination based upon the horizon tal as well as vertical synchronizing signals h and v from the photo image sensing system, the monitor television receiver is not directly necessary for the detection action. However, the monitor is only necessary in order to confirm the position of the object to be in spected and so on at the inspection starting time.Accordingly, inspection can not only be conducted without such influence of the moni tor screen becoming difficult to observe, or the brightness drop of the monitor screen, or further monitor trouble, but since it does not have to be constantly operated, the life of the monitor television receiver can be preserved for longer periods. In other words, the conver tional defects as above mentioned can almost entirely be avoided by this invention.

Further, as shown on Fig. 3B as an exam ple, when the object 21 flows in the direction indicated by an arrow 22 to the left on the monitor screen 19, as indicated on the draw ing, by setting the detection area 20 narrow and long in vertical direction on the monitor screen 19, inspite of the position of the object 21 being up or down, it can be surely de tected, and the blank period for the detection time can also be greatly reduced.

In order to establish the detection area 20 as illustrated on Fig. 3B, it is sufficient that the timing control circuit 1 2 so functions such that the output signal stv from the timing control circuit 1 2 by the vertical synchronizingk signal v shall be as per Fig. 5A, and the timing control circuit 1 3 functions such that the output signal sth from the timing control circuit 1 3 by the horizontal synchronizing sig nal h shall be established as per Fig. 5B.

Also as illustrated on Fig. 3C, when the object 21 flows vertically up and down on the monitor screen 1 9 as indicated by an arrow 23, by establishing the detection area 20 narrow and long in horizontal direction on monitor screen 1 9 as shown on the drawing, inspite of the object 21 being mispositioned to the right or left, it can be surely detected.

In order to establish the detection area 20 as shown on Fig. 3C, it is sufficient that the timing control circuit 1 2 functions such that the output signal stv from the timing control circuit 1 2 by the vertical synchronizing signal shall be set as shown on Fig. 6A and the timing control circuit 1 3 functions such that the output signal sth from the timing control circuit 1 3 by the horizontal synchronizing signal h shall be set as shown on Fig. 6B.

Whilst only a single preferred example of the present invention has been explained with reference to the drawings, variations and changes are possible as will be apparent to those skilled in the art.

Claims (3)

1. An object inspection or recognition system comprising: (a) a photo image sensing device picking up an object to be inspected and delivering a complex video signal; (b) means for separating horizontal and vertical synchronizing signals and a video signal from the complex video signal; (c) means for producing a comparative control signal based upon the horizontal and vertical synchronizing signals; (d) means for generating a reference signal; (e) means for comparing the video signal with the reference signal only within a period determined by the comparative control signal and producing an inspection start signal; and (f) means for inspecting the object when the inspection start signal is supplied thereto.

2. An object inspection or recognition system as claimed in claim 1, wherein said means for producing the comparative control signal include two timing control circuits which receive the horizontal and vertical synchronizing signals and produce strobe signals, respectively, and a strobe circuit which receives the strobe signals and then produces the comparative control signal.

3. An object inspection or recognition system substantially as herein described with reference to Fig. 2 of the accompanying drawings.