JPS626179B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a device that uses a television camera to capture an image of the surface of a standardized solid specimen such as a tablet, and inspects defects such as dirt, dust, and foreign matter on the surface. The present invention relates to a device that reliably detects a test object that is transferred in a line at high speed by the presence or absence of a video signal of the test object in each television scanning field, and performs an inspection using the video signal in any scanning field after detection.

Since pharmaceutical tablets enter the human body, sufficient hygiene must be taken into consideration. In particular, it is necessary to perform a 100% inspection to screen out defects such as stains, adhesion of foreign substances, and scratches on the surface of tablets that can be visually detected before they are made into final products.

Conventionally, this inspection has been carried out visually by multiple inspectors, but due to individual differences among inspectors, such as factors such as visual inspection ability, experience, and degree of fatigue, tablet inspection standards have varied, and visual inspection has Since the inspection speed is only about 3 tablets per second at most, it takes a lot of time to inspect all the tablets, and the number of inspectors currently occupies a large portion of the formulation process.

A tablet inspection device using a television camera has been developed with the aim of eliminating these drawbacks of conventional visual inspection, standardizing and improving inspection accuracy, and improving inspection processing speed. Using a television camera as a substitute for the human eye, defects such as stains and scratches are extracted from video signals in a certain scanning field corresponding to the tablet surface image by differentiation, and characteristic signals that do not occur in normal tablets are extracted. Inspection is carried out by making judgments, and due to the high-speed scanning of televisions, the inspection processing speed is at least 5 to 6 times that of conventional visual inspection, and as inspection accuracy improves, inspection standards can become constant. .

In this tablet inspection using a television camera, in order to make maximum use of the high-speed scanning of the television, a means is provided to place the tablets in the field of view of the television camera, that is, the inspection area, and sequentially transport the tablets. It is necessary to sample a scanning field that completely captures one tablet within the inspection area.

When sampling, in addition to the television inspection device, an optical sensor is placed in the field of view of the television camera just before the specimen is transferred, and the specimen is optically recognized by changes in the amount of reflection. , a delay time is set so that the object is completely included in the field of view of the television camera based on the transport speed of the object and the distance between the optical sensor and the position of the TV camera's field of view, and from optical recognition, after such delay time It is conceivable to sample the image information in one field of the corresponding television as the inspection target, but with this method of optically detecting the test object, it is difficult to detect the surface of a tablet, especially in the case of a curved shape such as a sugar-coated tablet. As a result, there are variations in light reflection, and because they are small and lightweight, subtle vibrations can greatly affect positional deviation, making optical recognition timing unstable and causing detection errors. .

The present invention relates to an apparatus for inspecting tablets, etc. using a television camera, and in order to eliminate sampling errors in one field that includes an inspection target and to ensure sampling of a field that includes an inspection target, an electrical connection is made in one screen of the television. The presence or absence of the video signal of the test object within the detection area set in the detection area is determined for each field, and if the video signal of the test object is within the detection area, detection recognition information is obtained. Within an inspection area that is electrically set in one screen, a video signal in an arbitrary field after recognition that completely includes the entire image of the object to be transferred is sampled, and defects are detected in this video signal. It is characterized by extracting features and performing a surface inspection of the object.

According to the present invention, since the detection of the object to be transferred is performed based on the presence or absence of image information of the object within the detection area set on the TV screen, there is a large degree of margin for vibration and positional deviation of the object to be transferred. Furthermore, since the object to be inspected is captured in a plane by a television camera, there is no error in detection timing due to differences in the shape of the object to be inspected, and sampling of the inspection field after detection is reliable. In addition, depending on the transfer speed of the test object and the pitch at which it can be transferred in a line, the detection area and the inspection area containing it can be placed at any position on the TV screen.
Electrical settings can be easily made to any size, so
The inspection ability can be fully demonstrated in accordance with the setting conditions of the field of view of the television camera, such as the magnification and the direction of transport within the field of view, for the object to be transported. In addition, a level comparator separates the level of the object and the background level from the video signal obtained by imaging the object, extracts the level signal of the object, and sends this level signal to a gate circuit that opens with a detection area mask signal. The level signal of the test object that has passed through the gate circuit is detected, and from the point of detection, a fixed field is used as the inspection field to detect scratches on the test object. Inspections can be carried out in the following conditions. That is, it is sufficient to simply detect that a level signal that captures the entire object under test has passed through a gate circuit controlled by a detection area mask signal, and the circuit configuration is simple.

Furthermore, when increasing the inspection capability by increasing the transport speed, when a normal illumination device is used, the image blurs due to the afterimage characteristics of a television camera, making it difficult to inspect with sufficient accuracy. To solve this problem, it is possible to use a solid-state image pickup camera or a non-storage type image pickup camera, but industrial television cameras, which are widely used, are extremely cheap and highly reliable.
By providing a strobe light as an illumination device that flashes in synchronization with the scanning of the TV 1 field, it is possible to inspect tablets that can be transported at high speed, and the inspection capacity can be improved.

Hereinafter, the features of the present invention will be explained with reference to figures using an example that deals with tablets.

FIG. 1 is a block diagram showing an implementation configuration of the present invention.

The tablet to be tested has an appropriate pitch and the TV camera 1
The tablet is sequentially transferred in a line within the visual field of the test tablet, and is converted into a video signal according to the surface condition of the tablet to be tested, and is output from the camera control unit 2 together with a horizontal synchronization signal and a vertical synchronization signal. The video signal is subjected to processing such as noise cancellation and signal amplification by a video signal processing circuit 3 and then input to a feature extraction circuit 4 and a level comparator 5.

It also includes a detection area for obtaining recognition information of the test tablet on the television screen by an area mask signal generation circuit 6 from the horizontal synchronization signal and the vertical synchronization signal output from the camera control unit 2, and the detection area. A timing pulse corresponding to the inspection area as an effective inspection range is generated. Furthermore, the area mask signal generation circuit 6 includes regulators 7 and 8 for adjusting the position and size of the detection area on the television screen, and regulators 9 and 10 for adjusting the position and size of the inspection area. It is equipped. A comparison level that allows the level comparator 5 to completely compare the surface level of the test tablet and the background level is set by the level setter 11, and the test tablet image is outputted as a pulse, and the pulse output is applied to the area mask. Through the detection area timing pulse outputted from the signal generation circuit 6 and the gate 12, only those included in the detection area are output as recognition signals.

The recognition signal is sampled in a test field sampling circuit 13 by sampling a certain field arbitrarily following the field from which the recognition signal was obtained as a test field, and outputs the test area timing pulse in the test field. The adjuster 14 is used to adjust the timing of how many fields after the recognized field are sampled as test fields.

In the feature extraction circuit 4, the defective portion is emphasized by differentiation or the like, and a positive judgment signal and a negative judgment signal are obtained by binarizing the positive peak and negative peak of the differential signal. The judgment signal thus obtained is transmitted through the inspection area timing pulse outputted from the inspection field sampling circuit 13 and the judgment signal in the inspection field through the gates 15 and 16, and the judgment circuit 17 judges the presence or absence of a defect, and performs tablet inspection. implement.

FIG. 2 shows the basic tablet inspection method in the implementation configuration according to the present invention. When a stain is present on the tablet surface as shown in a, one line of video signal b is obtained by scanning a line over the stain. A drop occurs at the spot due to the difference between the spot and the surface level, and when the video signal b is further differentiated, a differential signal c is obtained.
occurs. Here, the dirt on the tablet surface forms a sharp peak and is extracted together with the peak at the edge of the tablet. Here, features are extracted by differentiation, but the same effect can be achieved by performing second-order differentiation or extraction directly from the video signal via a comparator or the like.

In order to extract spots and edges from the positive peaks and negative peaks in the differential signal C, characteristic signals d and e are obtained which are pulsed at threshold levels P and N, respectively. In the case of a normal tablet, a peak always appears at the edge, so if the characteristic signals are counted in one line, each will be 1, and if there is a defect such as a stain, it will be 2 or more depending on the number of defects, such as d and e. In a certain field to be inspected, the characteristic signal is counted line by line, and if any line is counted 2 or more, the tablet to be inspected is determined to be defective.

FIG. 3 is a circuit diagram of the video signal processing circuit 3, in which operational amplifiers 18 and 19 constitute a low-pass filter and amplify the video signal output from the camera control unit 2.
Further, variable resistors 20 and 21 perform amplification gain adjustment and clamping of the atmospheric level.

FIG. 4 is a circuit configuration diagram of the feature extraction circuit 4, in which the shaped video signal output from the video signal processing circuit 3 is differentiated by a differentiating circuit constituted by an operational amplifier 22, and furthermore, the positive peak of the differentiated signal is , appropriate bias voltages to extract negative peaks.
V2+V3 is multiplied, comparators 23 and 24 perform zero level cross comparison, and gates 25, 26 and 27 are used to obtain binarized positive and negative determination signals of the same polarity. Further, by providing the comparators 23 and 24 with hysteresis, noise countermeasures are taken and stable comparison is possible. The positive and negative determination signals are sent to the determination circuit 17.
The tablets are counted for each line, and defect inspection information for tablets counted 2 or more is outputted to directly control the sorting machine or input to a computer to process the inspection information.

FIG. 5 shows a circuit configuration for generating the inspection area signal in the area mask signal generating circuit 6.
The figure shows the signal timing chart. Timing pulses a, b, c, and d shown in FIG. 6 are generated by off-delay circuits 28, 29, 30, and 31 triggered by the horizontal synchronizing signal and vertical synchronizing signal, and are inverted by inverting gates 32, 33, and AND gate 34, respectively. , 35 and 36, an inspection area signal e corresponding to the inspection area on the television screen is output. The horizontal position of the inspection area on the screen can be arbitrarily determined by the time constant adjuster 37 of the off-delay circuit 28, and the vertical position can also be determined by the time constant adjuster 39 of the off-delay circuit 30. Further, the size of the inspection area can be arbitrarily determined in the horizontal and vertical directions by the time constant adjusters 38 and 40 of the off-delay circuits 29 and 31. The circuit configuration for generating the detection area signal is the same as that shown in FIG. 5, and the time constant is set so as to be included in the inspection area depending on the transfer conditions of the tablet to be tested.

The above is the basic configuration of the area mask signal generation circuit 6, and FIG. 7 shows the state of the detection area and the inspection area generated on the TV screen. By having a plurality of basic configurations of the area mask signal generation circuit 6, it is possible to easily generate multiple inspection areas on the TV screen and perform simultaneous inspection of multiple rows. It is.

In FIG. 7, when an inspection area 42 is arbitrarily set within the television screen 41 and a detection area 43 is further set within the inspection area 42, there is an allowance in the vertical direction against mechanical positional deviation with respect to the transport trajectory of the test tablet 44. The position of the test tablet in the desired test field is determined based on the transport speed and the size of the test tablet in order to perform the test in a desired delayed field from a certain scanning field detected in the detection area 43. By providing a horizontal margin so as not to escape from the inspection area 42,
Easily generate optimal areas.

FIG. 8 shows the circuit configuration of the inspection field sampling circuit 13, in which the recognition information b obtained within the detection area is used as a reset signal, the vertical synchronization signal is used as a count clock, and the field count setting value up to an arbitrary inspection field is used. The presettable counter 45 and the gate 46 are configured so as to output a 1-field signal when the signal A is reached, and sample only the test field signal from the test area signal a.

Also, depending on the transport conditions, it is possible that one tablet may be recognized more than once within the detection area, but there may be a delay, such as prohibiting obtaining recognition information for the same tablet after obtaining certain recognition information. circuit 47,
and a gate 48. The timing of prohibition of this detection can be arbitrarily set using the delay time setting device 49, and regardless of the transfer conditions or the tablet size to be tested, one reliable detection per tablet and subsequent arbitrary field detection can be performed. A single sampling test is possible.

FIG. 9 shows an implementation configuration equipped with a strobe light according to the present invention, which is equipped with a flash signal generator 50 and a strobe light 51 that are completely synchronized with the vertical synchronization signal of the television, and can capture tablets that can be transported at high speed as if they were stationary. This makes it possible to perform highly accurate inspections without being affected by the afterimage characteristics of ordinary industrial television cameras, thereby improving inspection capabilities.

FIG. 10 shows an example of setting the inspection area and detection area for certain transfer conditions. In the case of transferring half a tablet to be tested within the field scanning time of the TV as the transfer speed, an inspection area 53 where 1.5 tablets to be tested can fit within the TV screen 52 in the transfer direction.
Set. Here, by setting the detection area 54 to have a width that is 1/3 of the inspection area 53 in the transport direction, the width of the detected field is The tablet positions are b and c, respectively, and are completely included in the inspection area 53.

In this case, by using the field next to the detection field as the inspection field, the number of inspection processes is increased, and as long as the interval between tablets that can be transferred is at least one tablet, images of more than two tablets will never exist in the inspection field. .

In this way, under the condition that half a tablet to be tested is transferred within the field scanning time, by setting the detection and inspection area as described above, the apparent resolution within the inspection area is increased and the transfer pitch is further reduced. It can be made small, and the optimum area can be set in consideration of improved inspection accuracy and high-speed processing. In addition, by setting an area on the screen that allows easy tracking of transfer conditions, settings can be made to prevent recognition errors and recognition timing errors caused by optical recognition methods, which were previously unavoidable when inspecting a wide variety of tablets. Eliminate the difficulties and recognize tablets quickly and reliably.
After recognition, highly accurate defect inspection can be performed in any field.

In this specification, the case where pharmaceutical tablets are used as the test object has been described, but it can also be used to test foods such as candy, pearls, and parts of precision instruments.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an implementation configuration of the present invention. FIG. 2 shows the basic method of tablet inspection in an embodiment of the present invention. FIG. 3 shows a circuit configuration of a video signal processing circuit in an embodiment of the present invention. FIG. 4 shows the circuit configuration of a feature extraction circuit in an embodiment of the present invention. FIG. 5 shows the basic circuit configuration of an area mask signal generation circuit in an embodiment of the present invention. FIG. 6 is a basic circuit signal timing chart of the area mask signal generation circuit in the embodiment of the present invention. FIG. 7 shows a detection and inspection area generated on a television screen in an embodiment of the present invention. FIG. 8 shows a circuit configuration of a test field sampling circuit in an embodiment of the present invention. FIG. 9 is a block diagram showing an embodiment of the strobe light of the present invention as a lighting device. FIG. 10 shows a method for optimally setting a detection and inspection area on a television screen in an embodiment of the present invention.

Claims (1)

[Claims] 1. A television camera installed near a transport means for orderly moving a standardized individual specimen to take an image of the specimen; a camera control unit connected to the television camera and outputting a video signal; a video signal processing circuit that performs analog processing on a video signal; a feature extraction circuit that extracts a feature signal of the object from the video signal after analog processing; and 2, a feature extraction circuit that compares the feature signal with a reference signal and binarizes it. The value conversion circuit generates an inspection area mask signal corresponding to the inspection area set within the TV screen and the minute detection area included in this inspection area from the horizontal synchronization signal and vertical synchronization signal output from the camera control unit. and a detection area mask signal, respectively; a level comparator that separates the level of the object and the background level from the video signal and extracts the level signal of the object; a first gate circuit that opens in response to a detection area mask signal to allow the output of the level comparator to pass; and a first gate circuit that is reset by the level signal that has passed through the first gate circuit to count the vertical synchronization signal; An inspection field sampling circuit samples a field immediately after the value reaches a predetermined value as an inspection field and passes the inspection area mask signal during this field period, and responds to the inspection area mask signal passed through this inspection field sampling circuit. An inspection device comprising: a second gate circuit that opens to allow the output of the binarization circuit to pass; and a determination circuit that determines the output of the second gate circuit for each horizontal period.