US3740467A

US3740467A - Apparatus for inspecting the appearance of products

Info

Publication number: US3740467A
Application number: US00214288A
Authority: US
Inventors: M Kubo; Y Arimura
Original assignee: Tokyo Shibaura Electric Co Ltd
Current assignee: Toshiba Corp
Priority date: 1970-12-31
Filing date: 1971-12-30
Publication date: 1973-06-19
Anticipated expiration: 1990-06-19
Also published as: JPS4814272B1

Abstract

An apparatus for inspecting the appearance of products is provided and includes an image pickup tube for photographing an image of a standard product whose appearance is complete and an image of a sample product whose appearance is to be inspected and for generating two video signals respectively corresponding thereto. Means are provided for delaying one of the two video signals which corresponds to either the standard product of the sample product. Further means are provided for comparing the delayed video signals corresponding to either the standard product or the sample product and the non-delayed video signals which correspond to the other of the two video signals to thereby obtain a comparison therebetween. In accordance with the comparison between the image signals of the standard product and the same of the sample product, it can be readily determined if the appearance of the sample product is the same or different from that of the standard product and accordingly whether a defect exists or not.

Description

United States Patent 1191 Kubo et al.

[ June 19, 1973 I APPARATUS FOR INSPECTING THE APPEARANCE OF PRODUCTS [75] Inventors: Moritada Kubo; Yoshiaki Arimura,

both of Tokyo, Japan [7 3] Assignee: Tokyo Shibaura Electric Company,

Ltd., Kawasaki-shi, Kanagawa-ken 22] Filed: Dec. 30, 1971 21 Appl. No.: 214,288

[30] Foreign Application Priority Data Primary Examinerl-loward W. Britton Attorney-Norman F. Oblon, Stanley P. Fisher, Marvin J. Spivak et a1.

57 ABSTRACT two video signals which corresponds to either the stan- Dec. 31, 1970 Japan 45/123630 da product of the Sample product. Fu ther means are 52 U.S. Cl. 178/6.8, l78/DIG. 37, 356/165, whparihg the delayed Vide" Signals I 356/167 356/240 responding to either the standard product or the sam- [5 t IIII I. ple produCt and the non-delayed Vlde? signals which [58] Field of Search l78/DIG. 33, DIG. 36, c0"hslohd the other the SBhah l78/DIG. 37, 6.8; 356/165, 166, 167,- 240 thereby obtain a comparison therebetweenjln accordance with the comparison between the image signals of the standard product-and the same of the sample [56] References Cited product, it can be readily determined if the appearance UNITED STATES PATENTS of the sample product is the same or different from that 3,049,588 8/1962 Barnett l78/DIG. 33 F i i lzmduct and accmdmgly whether a 2,460,350 2/1949 Hinman 356/166 S IMAGE PICKUP Q DEVICE b 1 Q i 8 r T SWEEP I 6 OSCILLATOR VT B l I SIGNAL GENERATOR b Pmmmwmm 3.740.467

SHEU 3 BF 3 SWEEP SlGNAL FIGS 20 23 2 2 22 g I SYNCHRONIZING PHASE MONOSTABLE GATE I SIGNAL SHIFTER MULTIVIBRATOR F SIGNAL REFLECT TRANSPARENT FIG. 6A

1/ STANDARD SAMPLE PRODUCT PRODUCT FIG.6B X Y X :t

FIG. 6(

' *lsLk FIG.6D v

0N OFF ON OFF FIGbF WW. I

FIG.6G l .4

FIG.6H T A APPARATUS FOR INSPECTING THE APPEARANCE OF PRODUCTS BACKGROU D OF THE INVENTION 1. Field of the Invention This invention generally relates to an apparatus for inspecting the appearance of products and more particularly to an'apparatus for inspecting to'determine the existence of cracks, splits, blots or the like which may appear on the outer surface of the products being inspected.

2. Description of the Prior Art Inthe mass production of products, such as electrical parts, household appliances made of metal, glass, wood, plastic or the like, it is necessary to inspect whether the appearance of the products are complete and flawless or whether there'exist certain impairments such as splits, blots or the like, on the outer surface thereof.

In the past, inspection was carried out by directly V toring personnel is required which results in a great expense. Moreover, since numerous inspectors are required to monitor the appearance of the products, different results may be produced depending upon the abilities ofa particular inspector and as a result thereof, certain defects may be overlooked. Additionally, the non-automated individual inspecting process of the prior art consumes a great deal of time.

SUMMARY OF THE INVENTION Accordingly, it is a primary object of thisinvention to provide a new and improved unique apparatus which is capable of quickly and relatively inexpensively inspecting the appearance of products with great accuracy.

Another object of this invention is to provide a new and improved unique apparatus which is capable of automatically inspecting the appearance of products.

Briefly, in accordance with the present invention; the foregoing and other objects are attained by the provision of an'apparatus for inspecting the appearance of products'by using an image pickup device for photographing an image of a standard product whose appearance is complete and and image of a sample product whose appearance is to be inspected and for generating two video signals respectively corresponding thereto. Meuns are provided for delaying either the video signals of the standard product or those of the sample product as obtained by the image pickup device. Further means are provided-for comparing the delayed video signals and the non-delayed video signals of the two video signals to thereby obtain a comparison there between, whereby the sample product is inspected to determine whether the appearnace thereof is the same or different from that of the standard product.

BRIEF DESCRIPTION OF THE DRAWINGS A more complete appreciation of the invention will be obtained as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings whereini FIG. 1 shows a schematic view of an appearance inspecting apparatus according to a preferred embodiment of this invention;

FIG. 2 shows a diagramatic plan view of the optical system shown in FIG. 1;

FIG. 3 shows a diagramatic side elevation view of the same; 7

FIG. 4 shows an enlarged partial view of the mirror sector shown in FIG. 1;

FIG. 5 shows a detailed block diagram of the gate signal generator shown in FIG. 1; and,

FIGS. 6a through 6h show time charts for illustrating the operation of the apparatus of this invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The apparatus of the present invention for inspecting the appearance of products will now be described with reference to FIGS. 1 through 6 wherein like reference numerals designate identical or corresponding parts throughout the several views.

Referring now to FIG. 1, the inspecting apparatus of the present invention is shown as including first and second revolving disks 1 and 2. The disks 1 and 2 are revolved with the same phase by motor 3, that is, the same speed and, for example, in the direction shown by the arrow a. A standard product A whose appearance is correct and complete, that is, one which has no cracks, splits, blots or the like, is placed on the first disk 1.. On the other hand, a sample product B to be inspected and whose appearance is supposed to be the same as the standard product A is placed on the second disk 2. It is desirable to set the standard product A and the sample product B to be inspected with their corresponding surfaces being arranged in the same direction with respect to an image pickup device, that is, to match their phases. It should be understood, however, that such a corresponding arrangement is not necessarily required. Thus, if the phase between the two products is shifted, the same can be easily adjusted by electrically controlling a phase shifter which is described in more detail hereinafter. Now, it will be easily underfirst and second disks 1 and 2 are revolvedwith the I same phase.

A plurality of first lighting sources 4, s and 6 are revided above the first disk 1 in order to illuminate the standard product A. The

lighting sources

4, 5 and 6 are arranged at a predetermined angle 0 with respect to the plane of the first disk 1 as shown in the respective plan and side elevation views of FIGS; 2 and 3. The respective angles 0 of the

lightingsources

4, 5 and 6 are 42,, b2) and In the same manner, a plurality of second lighting sources 7, 8 and 9 are arranged above the second disk 2 at a predetermined angle 0 as shown in FIGS. 2 and 3. Here the respective angles 0 of the lighting sources 7, 8 and 9 are 41,, @11 and 4: Thus, it should be apparent that the standard product A and the sample product B are illuminated with substantially the same luminance.

The first and the second lighting sources may be, for example, fluorescent lamps, incandescent lamps or lamps of the electroluminescence type.

Now, turning again to FIG. 1, it is seen that an image pickup device 11 'is provided at the right hand side of the first disk 1 and the second disk 2. The image pickup device 11 includes a camera or a pickup tube, such as an image orthicon camera tube or a videcon camera tube, in order to enable an optical image of the products A and B to be scanned and to thereby develop output voltages which vary in accordance with the light intensity of the successive elements of the images. The light reflected from the sample product, B due to the second lighting sources 7, 8 and 9 is reflected by an optical mirror 12, which in turn is received by the image pickup device 11 through an optical interrupting means or chopper 13 and a lens 10. The optical interrupter 13 is, for example, a mirror sector which is arranged in such a position that the light reflected from the standard product A due to the

lighting sources

4, 5 and 6 and thelight reflected from the sample product B due to the lighting sources 7, 8 and 9 meet at right angles with each other. It should be understood that the mirror sector or the chopper 13 are conventional in the art and may take any desired form. One example of a suitable mirror sector or chopper will be described with reference to FIG. 4. I

In FIG. 4, the mirror sector l3'is shown as a thin circular plate which includes a light reflection portion or a mirror portion 40-and a light transparent portion, a cut out portion or a non-mirror portion 41. The width C of the mirror portion 40 and the width D of the cut out portion 41 are made substantially equal. The mirror sector 13 may be made, for example, by evaporating Aluminum (Al) on the surface of a circular glass or metal plate to make the mirror portion 40 and then by selectively removing the peripheral portion of the Aluminum evaporated plate to make the cut out portion product B partially overlap due to the rotation of the mirror sector 13.

Now referring again to FIG. 1, it is seen that a synchronizing signal generator 15 is provided at the pe ripheral portion of the mirror sector 13 to generate syn-.

chronizing signals for synchronizing the image signals from the mirror sector 13 and the output signals of the image pickup device 11, that is, to distinguish whether the light image which enters the image pickup device 1 1 is the light image from the standard product A or the light image from the sample product B. The synchronizing signal generator 15 is conventional in the art and may by example consist of a photoemitting device or a light source 16, such as a lamp, and a photoreceiving device 17, such as a phototransistor, photocell or phototube. The photoreceiving device is arranged on an opposite side of the mirror sector 13 to that of the photoemitting device so as to interpose the peripheral portion of the mirror sector 13 therebetween. The synchronizing signal generator 15 will alternatively and in turn pass through the cut out portion 41 of the mirror sector 13 and be intercepted by the mirror portion of the mirror sector 13 shown in FIG. 4. The photoreceiving device. 17 will in turn intermittently receive the light from the light source 16 and thereby produce pulses which are used as the synchronizing signals. A typical waveform for the synchronizing signals so generated is shown in FIG. 6c.

The synchronizing signals thus obtained and the output signals from a sweep oscillator 18 of the image pickup device 11 are applied to a gate signal generator 19. The gate signal generator 19 is actuated by synchronizing the operation of the mirror sector 13 with the sweep output signals from the sweep oscillator 18.

The details of the gate signal generator 19 will now be explained with reference to FIG. 5.

Now turning again to FIG. 1, it is seen that the mirror 13 is rotated about its central axis by a motor 14, so that the light reflected from the standard product A and the sample product B may be alternatively chopped by turns. The light reflected from the standard product A and the sample product B thereby will alter? natively enter the camera tube of the image pickup device 11 by turns. That is, the light reflected from the standard product A is reflected by the mirror portion 40 of the mirror sector, 13 and thereafter enters the camera tube of the image pickup device 11. On the other hand, the light reflected from the sample product B will pass through or penetrate the cut out portion 41 of the mirror sector 13 and thereafter enter the camera tube of the image pickup device 11. As a result of the above, the image pickup device 11 will alternately photograph thestandard product A and the sample product B which rotateiwith the same phase and under the same lighting conditions.

The operation of the mirror sector 13 and'the image pickup tube 11 are respectively shown in the time chart of FIGS. 6a and 6b. It can be clearly understood from FIG. 611 that the image or reflected light of the standard product A and the sample product 8' are alternately reflected and penetrated by the mirror sector 13 and that the boundary of the reflected light zone of the standard product A and the penetrated light zone of the sample In FIG. 5 the gate signal generator 19 is shown as including a phase shifter 20, a monostable multivibrator or a one shot multivibrator 21, an inverter 22 and a bistable-multivibrator or a flip-flop 23. More particularly, the synchronizing signals from the synchronizing signal generator 15 of FIG. 1 are appliedto the phase shifter 20 which may, for example, include a monostable multivibrator. In the phase shifter 20, the phase of the synchronizing signals are adjusted and at the same time the output pulses of the monostable multivibrator thereof are controlled by controlling the time constant of the monostable multivibrator so as to have a time width which corresponds to the width S of the overlapping portions shown in FIGS. 6a and 6b. In this manner the overlapping portions are thereby eliminated. It should be understood that the above mentioned phase adjustment is carried out in order to synchronize the synchronizing signals from the synchronizing signal generator .15 and the image signals of the standard product A and the sample product B from the mirror sector 13.

In case the phase of the synchronizing signals are shifted as shown in FIG. 6c, it is necessary to advance the phase thereof to thereby obtain the output pulses having a pulse width S as shown in FIG. 6d. I

The output pulses produced by the phase shifter 20 are, in turn, transmitted to the monostable multivibrator 21 whereby output pulses having a pulse width (T-S) are obtained as shown in FIG. 6e. It should be understood that T stands for a period wherein the image pickup device 11 alternately photographs the standard product A and the sample product B.

The output pulses produced by the monostable multivibrator 21 are then applied directly to one input terminal of the flip-flop 23, which may be for example a J-K flip-flop, an R-S flip-flop or an R-S-T flip-flop, and to another input terminal thereof through the inverter 22. Vertical synchronizing signals from the sweep oscillator 18 are applied to a trigger input terminal of the flipflop 23. FIG. 6f shows one example of the vertical synchronizing signals and FIG. 6g shows the output or gate signals generated from the flip-flop 23.

The gate signals so obtained atan output of the flipflop 23 are applied as shown in FIG. 1 to an AND gate 24 along with the video signals produced by the image pickup device 11. In this manner, the AND gate 24 is controlled by the gate signals such that video output signals of the standard product and the sample product are obtained which are completely separated from each other as shown in FIG. 6h.

As can clearly be seen from FIG. 1, the video signals from the AND gate 24 are respectively appliedto a magnetic writing head 25 of a delaying means, such as a video tape recorder, and to one input terminal 28 of a comparator 27. The comparator 27 may conventionally be a subtracting circuit or-a diode comparator which includes an operational amplifier and a diode.

The writing head 25 serves to' write the video signals from the AND gate 24 on a magnetic tape 26 which is running in the direction shown by the arrow b and with a speed V.

The videosignals which are written on the magnetic tape 26 are then read out by a magnetic readout head 29 which'is set at a distance VT away from the writing head 25. The video signals read out by the readout head 29 are, in turn, applied to the input terminal 30 of the comparator 27. Thus, it is seen that after delaying the video signals corresponding to either the standard product or the sample product for a predetermined time, for example the period T, the same are applied to the input terminal 30 of the comparator 27.

It should be understood that the time delay may be determined in accordance with the frequency of the sweep signal from the sweep oscillator 18, the amount of rotation of the mirror sector 13 and the amount of rotation of the disks 1 and 2. Thus, the time delay cannot be determined indiscriminately but must be selected such that the video signals of the standard product and the corresponding video signals of the sample product are simultaneously applied to the comparator 27. Accordingly, the two video signals, that is, the nondelayed video signals and the delayed video signals are simultaneously and respectively applied to the input terminals 28 and 30 of the comparator 27. In the comparator 27, the non-delayed signals and the delayed signals are thereby compared to provide a signal indicative of a balance or a difference therebetween. It will be clearly understood that if, for example, the delayed video signals correspond to the standard product and the non-delayed video signals correspond tothe sample product that the standard product and the sample product are compared by the comparator 27. A judging means 31 is provided for deciding and indicating whether or not a balance exists between the video signals of the sample product and the standard product. The judging means 31 may be of a type that produces output signals if input signals representing a different output from the comparator are applied thereto and will not produce output signals if no input signals representing a balance output from the comparator 27 are applied thereto. By way of example, the judging means 31 may be a zero point detecting circuit which includes a fullwave rectifier. Such a judging means will produce signals only when a difference between the standard product and the sample product occurs and therebyactuates an alarm 33. Simultaneously with the actuation of the alarm 33, the defective portion of the sample product so indicated is displayed by a television monitor 32 and if necessary the rotation of the disks 1 and 2 are stopped.

It should be understood that while in the above embodiment, a mirror sector was used to alternately photograph the image of the standard product and the sample product, the invention is not so limited and that a semitransparent mirror having a reflective rate of about 50 percent or other optical choppers may be readily used. Moreover, while in the above embodiment a magnetic tape was used to delay the video signals of the product, it should be understood that the invention is not so limited and that other delay means, such as delay lines, semiconductor memoriesand the like may be readily used.

It should now be apparent that the present invention as described hereinabove provides an apparatus suitable for inspecting the appearance of the products, more quickly, economically and perfectly than heretofore existed. Moreover, it is apparent that this invention is advantageous in that the inspection can be performed automatically, so that the requirement for high skill is eliminated. The present invention is thus quite suitable for the mass production of products.

Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

What is claimed as new and desired to be secured by Letters Patent of the United States is:

1. An apparatus for inspecting the appearance of products comprising: I

an image pickup device for alternately photographing a standard productwhose appearance is complete and a sample product whose appearance is to be inspected and for providing two video signals corresponding thereto;

means for delaying one of the two video signals corresponding to one photograph of either said standard product or said sample product;

means for comparing said delayed video signals and the remaining non-delayed video signals of said two video signals to thereby obtain a comparison therebetween;

whereby in accordance with said comparison the appearance of said sample product is inspected to determine whether or not it is the same as that of said standard product. I

2. The inspecting apparatus according to claim 1, in which an optical interrupter is provided between said image pickup device and said products.

3. The inspecting apparatus according to claim I, which further includes means for rotating said standard product and sample product with the same phase.

4. An apparatus for inspecting the appearance of products comprising:

means for rotating with the same phase a standard product whose appearance is complete and a sample product whose appearance is to be inspected;

means for alternately photographing said standard product and said sample product;

an optical interrupting means provided between said products and said image pickup device so as to allow images of said products to alternately enter into said image pickup device such that two video signals respectively corresponding to said standard product and said sampleproduct are produced;

a synchronizing signal generator for generating synchronizing signals for'synchronizing said optical interrupting means;

a sweep oscillator for generating sweep signals for said image pickup device;

a gate signal generator having said sweep signals and said synchronizing signals applied thereto for generating gate signals;

an AND gate having said gate signals and said two video signals from said image pickup device applied thereto for separating said two video signals into that of said standard product and that of said sample product;

means for delaying one of said two video signals which corresponds to either said standard product or said sample product;

means for comparing said delayed video signals and said other non-delayed video signals of said two video signals to obtain a comparison therebetween;

whereby in accordancewith said comparison the appearance of said sample-product is inspected to determine whether or not it is the same as that of said standard product. I

5. The inspecting apparatus according to claim4, in

which said gate signal generator comprises:

a phase shifter whose input is connected to said synchronizing signal generator;

a monostable multivibrator connected to the output of said phase shifter; and

a bistable multivibrator connected to the output said monostable multivibrator.

6. The inspecting apparatus according to claim 4, in which said delaying means comprises a video tape recorder having separately arranged reading and writing heads.

7. The inspecting apparatus according to claim 4, in which said phase shifter comprisesa monostable multivibrator.

8. The apparatus according to claim 4, in which is further comprised a means for displaying any defect of said sample product as determined in accordance with said comparison.

9. The inspecting apparatus according to claim 4, in which is further comprised an alarm means which is activated by a defect in said sample product as determined in accordance with said comparison.

10. The inspecting apparatus according to claim 4, in which said optical interrupting means comprises a circular plate having a plurality of light reflective portions and a plurality of light transparent portions that are alternately arranged at the peripheral portion thereof; said light reflective portions and said light transparent portions having a same constant width.

11. The inspecting apparatus according to claim 10,

I in which saidsynchronizing signal generator comprises rupting means therebetween.

Claims

1. An apparatus for inspecting the appearance of products comprising: an image pickup device for alternately photographing a standard product whose appearance is complete and a sample product whose appearance is to be inspected and for providing two video signals corresponding thereto; means for delaying one of the two video signals corresponding to one photograph of either said standard product or said sample product; means for comparing said delayed video signals and the remaining non-delayed video signals of said two video signals to thereby obtain a comparison therebetween; whereby in accordance with said comparison the appearance of said sample product is inspected to determine whether or not it is the same as that of said standard product.

3. The inspecting apparatus according to claim 1, which further includes means for rotating said standard product and sample product with the same phase.

4. An apparatus for inspecting the appearance of products comprising: means for rotating with the same phase a standard product whose appearance is complete and a sample product whose appearance is to be inspected; means for alternately photographing said standard product and said sample product; an optical interrupting means provided between said products and said image pickup device so as to allow images of said products to alternately enter into said image pickup device such that two video signals respectively corresponding to said standard product and said sample product are produced; a synchronizing signal generator for generating synchronizing signals for synchronizing said optical interrupting means; a sweep oscillator for generating sweep signals for said image pickup device; a gate signal generator having said sweep signals and said synchronizing signals applied thereto for generating gate signals; an AND gate having said gate signals and said two video signals from said image pickup device applied thereto for separating said two video signals into that of said standard product and that of said sample product; means for delaying one of said two video signals which corresponds to either said standard product or said sample product; means for comparing said delayed video signals and said other non-delayed video signals of said two video signals to obtain a comparison therebetween; whereby in accordance with said comparison the appearance of said sample product is inspected to determine whether or not it is the same as that of said standard product.

5. The inspecting apparatus according to claim 4, in which said gate signal generator comprises: a phase shifter whose input is connected to said synchronizing signal generator; a monostable multivibrator connected to the output of said phase shifter; and a bistable multivibrator connected to the output said monostable multivibrator.

7. The inspecting apparatus according to claim 4, in which said phase shifter comprises a monostable multivibrator.

11. The inspecting apparatus according to claim 10, in which said synchronizing signal generator comprises a photoreceiving device and a photoemitting device each being arranged on opposite sides of said optical interrupting means so as to interpose said optical interrupting means therebetween.