JP3243541B2 - Tablet appearance inspection method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the appearance of a tablet, and more particularly, to a method for inspecting the surface of a tablet on which a symbol is printed for a defective appearance. In this specification, the term symbol is used in its broadest sense, including all letters, signs, and the like. In addition, poor appearance of tablets means
It shall include all abnormalities in appearance such as printing stains on the tablet surface, chipping and shading of printing symbols, foreign matter, cracks, chips, and cracks on the tablet.

[0002]

2. Description of the Related Art As a method of inspecting the appearance of a tablet of this kind, a predetermined symbol inspection range including a symbol portion is set on the surface of a tablet on which a symbol is printed, and the symbol inspection range is imaged by a two-dimensional imaging device. The symbol inspection range is equally divided into a plurality of unit dots in a horizontal scanning direction and a vertical scanning direction by a horizontal scanning line of the video signal and a predetermined clock signal, and a video signal corresponding to each unit dot is determined by a predetermined threshold. 2 by value
It is known to determine the presence or absence of a defective appearance in the symbol inspection range of a tablet based on the number of one value of binarized video data of each unit dot (see Japanese Patent Laid-Open No. 2-27239).
Reference).

In this method, the area of a symbol portion or a symbol-free portion within a symbol inspection range is determined from the number of one value of the binary video data of each unit dot, and this area is determined by a predetermined allowable value. The presence / absence of the appearance defect is determined by comparing with.

[0004]

Generally, printing a symbol on a tablet cannot be as sharp as printing on paper, and the printed symbol becomes thicker or thinner.

[0005] Therefore, in the above-described conventional method of judging pass / fail based on the area of a symbol portion or a symbol-free portion within the symbol inspection range, the presence or absence of printing or large chipping can be detected. Cannot be determined. In particular, the quality of a mark No having a small character cannot be accurately determined. In the case where a missing symbol and a stain on a portion originally having no symbol occur simultaneously,
A defective product may be erroneously determined as a good product.

An object of the present invention is to solve the above problems,
It is an object of the present invention to provide a tablet appearance inspection method capable of accurately inspecting the presence or absence of appearance defects on the surface of a tablet on which a symbol is printed.

[0007]

The method according to the invention comprises:
A predetermined symbol inspection range including the symbol portion is set on the surface of the tablet on which the symbol is printed, the symbol inspection range is imaged with a two-dimensional imaging device, and the horizontal scanning line of the video signal and a predetermined clock signal are used for the above. The symbol inspection range is equally divided into a plurality of unit dots in the horizontal scanning direction and the vertical scanning direction, and the video signal corresponding to each unit dot is binarized into a bright portion and a dark portion by a predetermined threshold value. A method for inspecting the presence or absence of appearance defects in the symbol inspection range of the tablet by processing the digitized image data, wherein a plurality of inspection dots are set from unit dots within the symbol inspection range, and each inspection is performed. For the dot, binarized non-defective data indicating whether the dot is a bright portion or a dark portion in the case of a non-defective item is set, and
The method determines the presence or absence of the appearance defect in the symbolic test range by comparing the binary image data for each test dots of said symbol test range binarized good data of the test dot
In the symbol inspection range, the vertical scanning direction
Horizontal through the unit dot which is the darkest part at one end
The axis in the scanning direction is the horizontal reference axis, and one of the horizontal scanning
Vertical scanning method through the unit dot which is the darkest part at the end
The vertical axis is the vertical reference axis.
The relative coordinate value with the axis as the reference coordinate axis
It is characterized by indicating a position .

Preferably, when the number of inspection dots whose binary image data does not match the binarized non-defective data is larger than a predetermined allowable value, it is determined that there is a defective appearance in the symbol inspection range.

Further, preferably, the plurality of inclined posture rotated by a predetermined angle the tablet from the normal position and the normal position, may be set the position and the binarized good data for each test dot, respectively, either posture When it is determined by the comparison between the binarized video data and the non-defective binarized data that there is no appearance defect in the symbol inspection range, it is determined that there is no appearance defect in the symbol inspection range.

[0010]

[Action] A plurality of inspection dots are set from among the unit dots within the symbol inspection range on the tablet surface, and each inspection dot is a binarized non-defective item indicating whether the non-defective item is a bright portion or a dark portion. Since the data is set and the binarized video data of each inspection dot in the symbol inspection range is compared with the binarized non-defective data of the inspection dot, the presence or absence of the appearance defect in the symbol inspection range is determined. Defects in the shape of the printed symbol can also be reliably inspected.

In the symbol inspection range, one of
Horizontal run through the unit dot which is the darkest end of the
The axis in the scanning direction is the horizontal reference axis, and
The vertical scanning direction that passes through the unit dot, which is the dark part at the end
Is the vertical reference axis, these horizontal reference axis and vertical reference axis
The position of each inspection dot is determined by the relative coordinate value with
Position, so even if the tablet position is slightly shifted,
Inspection of defects is possible .

If the number of inspection dots whose binary image data does not match the binarized non-defective data is larger than a predetermined allowable value, it is determined that there is a defective appearance in the symbol inspection range. Can be easily determined.

[0013] The plurality of inclined posture rotated by a predetermined angle a tablet agent from the standard position and the normal position, the binarized good data for each test dots may be set respectively, the binary image data in either orientation When it is determined that there is no defective appearance in the symbol inspection range by comparing the data with the binarized non-defective product data, it is determined that there is no defective appearance in the symbol inspection range. Inspection of poor appearance can be surely performed.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a main part of a tablet printing machine and a visual inspection device. FIG. 3 shows an example of the tablet (T).

As shown in FIG. 3, a predetermined symbol (M) is printed on the surface of the tablet (T) by a printing machine. In this embodiment, no printing is performed on the back surface of the tablet (T). In the drawing showing the tablet (T), the printed symbol (M) is indicated by hatching.

The printing press is the same as the tablet printing press described in the above-mentioned JP-A-2-27239.

The printing press has a first rotating shaft about a horizontal axis.
A tablet supply roll (first roll) (1) is provided.
In the outer peripheral surface of the first roll (1), pockets for vacuum-sucking the tablet (T) are provided at a plurality of positions equally dividing the first roll in the circumferential direction.
(2) is provided for each of a plurality of columns (see FIG. 2). The first roll (1) is rotated at a constant speed in the counterclockwise direction in FIG.

A printing device is provided on the left side of the first roll (1) in FIG.
(3) is provided.

A tablet hopper (not shown) is provided diagonally above and to the right of the first roll (1) in FIG. 1, and tablets in the hopper are provided.
(T) is held one by one in the rotating pocket (2) of the first roll (1). At this time, the surface of the tablet (T) facing the outside of the pocket (2) is the surface. The tablet (T) held in the pocket (2) rotates with the rotation of the first roll (1), and during this time, a symbol is printed on the surface by the printing device (3).
While the printed tablet (T) is held by the first roll (1) and rotated, the appearance inspection device inspects the surface for appearance defects, and detects defective products with a defective product discharge chute (not shown). ) And the other tablets (T) are in the first roll (1)
Is transferred to a pocket of a similar second roll (not shown) adjacent thereto, and is rotated by being held by the second roll so that the back surface faces outward. And the tablet held by the second roll
While the (T) is rotating, another appearance inspection device (not shown) inspects the appearance of the back of the tablet (T) for defects, and passes a good product to a good product discharge chute (not shown) and discharges a defective product to a defective product. It is discharged to a chute (not shown).

As shown in FIG. 1, the visual inspection apparatus comprises an inspection position sensor (4), a television camera (5), an input / output circuit (6), a frame memory (7), a binarization counter (8), a window It includes a board (9), a synchronization signal generation circuit (10), a microcomputer CPU (11), and a monitor display (12).

The inspection position sensor (4) detects when the pocket (2) of the first roll (1) reaches a predetermined inspection position and outputs a trigger signal. This trigger signal is input to the CPU (11) through the input / output circuit (6).

The television camera (5) constitutes a two-dimensional imaging device for imaging the tablet (T) held in the pocket (2) coming to the inspection position, and is provided by the number of rows of the pocket (2). Have been. As the TV camera (5), for example, a CCD
One having a random shutter function is used.

The synchronizing signal generation circuit (10) is a television camera
(5) Binary counter (8), window board (9), CP
It generates synchronization signals such as a vertical synchronization signal, a horizontal synchronization signal, and a field index signal so that U (11) operates in synchronization with each other.

The frame memory (7) is an image memory that can be freely read and written by the CPU (11). Frame memory
In (7), the television screen is equally divided into a plurality of unit dots by a horizontal scanning line and a predetermined clock signal based on the video signal of the television camera (5), and the video data of each unit dot is stored in a corresponding address. Is done. The video data stored in the frame memory (7) is digitized video data obtained by digitizing the luminance value of each unit dot. Further, the frame memory (7) outputs the digitized video data stored therein as a digitized video signal. In the case of this embodiment, the frame memory (7) operates by generating a synchronization signal from the video signal of the television camera (5).
The television screen is equally divided into 256 vertical and horizontal unit dots. As shown in FIG. 4, the position of each unit dot is
Using the X axis as the axis in the horizontal scanning direction at the upper end of the TV screen and the Y axis as the axis in the vertical scanning direction at the left end of the TV screen,
The pitch of the unit dot is represented as 1. The right direction of the television screen is defined as the positive direction of the X axis, and the downward direction is defined as the positive direction of the Y axis. In the drawing showing the tablet (T) as shown in FIG. 3 and the drawing showing the television screen as shown in FIG. 4, corresponding parts are denoted by the same reference numerals.

The binarization counter (8) binarizes the digitized video data corresponding to each unit dot of the television screen with a predetermined threshold value, and converts the digitized video data representing a bright portion (bright portion). And binarized video data representing a dark portion (dark portion), and outputs the binarized video data as a binarized video signal, and counts the number of unit dots that are dark portions as described later. Things. In this embodiment, the binarized video data representing a bright portion is "0", and the binary video data representing a dark portion is "1".

The window board (9) is for storing window information representing an inspection window to be described later, and has a window memory having the same capacity as the frame memory (7).

The CPU (11) controls the entire appearance inspection apparatus, and outputs a determination result through the input / output circuit (6).

The display (12) is for displaying a television image or the like of the tablet (T). Note that, in the drawing showing the television image, a portion that becomes a dark portion when binarized is indicated by hatching.

On the surface of the tablet (T), FIG.
In addition, two inspection windows as shown in FIG. 4, that is, a symbol inspection window (symbol inspection range) (W0) and a margin inspection window (W1) are set. Symbol inspection window (W0)
Is the portion inside the rectangular symbol inspection window frame (F0) and contains the printed symbol (M). Margin inspection window
(W1) is a margin portion inside the circular margin inspection window frame (F1) slightly inside the outer peripheral edge of the tablet (T) and outside the symbol inspection window frame (F0) where the original symbol is not printed.

The setting of these windows (W0) and (W1) is performed as follows with the window setting mode selected.

When the window setting mode is selected, the first
When the roll (1) is rotated, the pocket (2) comes to the inspection position, and a trigger signal is output from the sensor (4), the shutter of the television camera (5) opens and the pocket (2) is opened. The held tablet (T) is imaged. And TV camera (5)
Is input to the frame memory (7), and the digitized video data corresponding to each unit dot is
Stored in (7). Thus tablets with TV camera (5)
The operation from when (T) is imaged until the digitized video data is stored in the frame memory (7) is referred to as image input. In the window setting mode, image input is performed only once. When the image input is completed, each time the vertical synchronization signal is output, the digitized video signal is sent from the frame memory (7) to the display (12) through the binarization counter (8), and the first imaged tablet (T) Is displayed.
In the case of a normal tablet (T), as shown in FIG. 4, the portion of the symbol (M) of the tablet (T) is a dark portion, the remaining blank portion is a light portion, and the first roll around the tablet (T). The part (1) is a dark part. Among the abnormalities on the surface of the tablet (T), the portion lacking the symbol (M) is a bright portion, the portion stained by printing, and the portion lacking the tablet (T) is a dark portion. At the same time as the still image of the tablet (T), two standard window frames (F0) and (F1) are displayed on the display (12). Set the size windows (W0) and (W1). Further, on the screen of the display (12), four reference points for position determination (P1) (P2) (P3) (P4) for determining a tablet position described later are set. These reference points (P1) to (P4) are set to positions on the screen where a part without a symbol on the surface of the tablet (T) always comes even if the position of the tablet (T) slightly shifts up, down, left and right. First reference point (P
The first reference point (P2) is located near the left end of the tablet (T) in the vertical direction, and the third reference point (P3) is located near the right end of the tablet (T) in the vertical direction. Is set at a position near the upper end of the center of the tablet (T) in the left-right direction, and the fourth reference point (P4) is set at a portion near the lower end of the center of the tablet (T) in the left-right direction. Further, a threshold value for binarization and a size of a pitch of inspection dots to be described later are set. The size of the pitch of the inspection dots is appropriately set in consideration of the shape of the symbol (M), and is set to, for example, about four times the pitch of the unit dot. In this case, if the pitch of the unit dot is about 0.06 mm,
The size of the pitch of the inspection dots is about 0.2 to 0.3 mm .

When the above settings are completed, an instruction to complete the settings is issued.

When the setting completion is instructed, the CPU (11)
The positions (XY) of the four reference points (P1) to (P4) on the television screen
(Coordinate values) in the memory, and these reference points (P1) to (P4)
Then, the center position of the tablet (T) on the television screen is obtained based on the digitized video data stored in the frame memory (7), and the XY coordinate value is stored in the memory as the center position reference value. Further, the CPU (11) stores the window information in the window memory of the window board (9) based on the set positions of the windows (W0) and (W1). Further, the CPU (11) stores the set threshold value for binarization and the size of the pitch of the inspection dots in the memory.

The center position of the tablet (T) can be obtained as follows. First, with the first reference point (P1) as a starting point, the luminance of each unit dot is examined while shifting the unit dots one by one toward the outside (left side). As long as the luminance is greater than the binarization threshold, the unit dot is
It is determined that the point is on (T), and the position of the unit dot at which the luminance changes from a value larger than the threshold to a value smaller than the threshold is taken as the position of the left end of the tablet (T). Next, the position of the right end of the tablet (T) is similarly obtained while shifting the unit dots one by one toward the outside (right side) with the second reference point (P2) as a starting point. Then, an average of the positions of the left end and the right end of the tablet (T) is averaged, and this is set as the X coordinate value of the center of the tablet (T). Similarly, the position of the upper end of the tablet (T) is determined starting from the third reference point (P3), and the position of the tablet is determined starting from the fourth reference point (P4).
The position of the lower end of (T) is obtained, and the average of these positions is defined as the Y coordinate value of the center of the tablet (T).

The window information is stored in such a manner that the content of the memory corresponding to the margin inspection window (W1) among the window memories is "1", and the content of the remaining memory is "0". The symbol inspection window (W0) set and stored in the window setting mode in this manner is referred to as a reference symbol inspection window, and the margin inspection window (W1) is referred to as a reference margin inspection window.

Among the above operations in the window setting mode, selection of the window setting mode, the inspection window
The setting of (W0) and (W1), the setting of the reference points (P1) to (P4), and the instruction of the completion of setting are manually performed by a person, but other operations are automatically performed by a command from the CPU (11). . When the window setting mode is selected and the still image of the tablet (T) is displayed, if the image is not normal, the window setting mode may be repeatedly selected until a normal image is obtained.

When the setting of the inspection windows (W0) and (W1) is completed, teaching is performed prior to the inspection. In this teaching, a plurality of inspection dots are set from among the unit dots in the symbol inspection window (W0), and each of the inspection dots is a binarized non-defective product indicating whether the non-defective product is a bright portion or a dark portion. This is preparation work for setting data. In the teaching, the digitized video data of the frame memory (7) corresponding to the unit dot in the symbol inspection window (W0) is binarized, and by examining the binarized video data, the unit dot becomes a bright portion. Or a dark part is determined. Next, the teaching operation will be described with reference to the flowchart in FIG.

When the teaching mode is selected, first, image input is performed only once, as in the window setting mode (step 101). Next, using the four reference points (P1) to (P4) stored in the window setting mode, the tablet imaged just like the window setting mode is used.
The center position of (T) is obtained (step 102). Next, the difference between the center position obtained in this way and the center position reference value previously stored in the window setting mode is used as a window correction amount (step 103). Is corrected, and the corrected position information of the symbol inspection window (W0) is stored in the memory (step 104). With this correction, the positional relationship of the corrected symbol inspection window (W0) with respect to the center position of the tablet (T) just imaged is equal to the positional relationship of the reference symbol inspection window with respect to the center position reference value of the tablet (T). . That is, the position of the symbol inspection window (W0) is corrected according to the actual position of the tablet (T). Next, the x-axis (horizontal reference axis) and the y-axis (vertical reference axis) shown in FIG. 5 are set in the corrected symbol inspection window (W0) (step 105). The x-axis is the axis in the horizontal scanning direction passing through the uppermost unit dot among the unit dots of the dark part in the symbol inspection window (W0), and the y-axis is the unit dot of the dark part in the symbol inspection window (W0). This is an axis in the horizontal scanning direction passing through the unit dot at the uppermost end. Next, the symbol inspection window
In (W0), a plurality of test dots (C) are set with the pitch stored in the window setting mode (step 106). Next, the set position of the inspection dot (C) and binarized non-defective data are stored (step 107).
The position of the inspection dot (C) is represented by a relative coordinate value using the x-axis and the y-axis as reference coordinate axes. Good binary data is
This indicates whether each inspection dot is a bright part or a dark part when the inspection dot is a good product, and is set to “0” when the inspection dot is a bright part and is set to “1” when the inspection dot is a dark part. You. At this time, for each inspection dot, a unit dot in the vicinity thereof is examined. If the inspection dot set in step 106 comes near the boundary between the bright part and the dark part as shown by reference numeral (A) in FIG. Then, the inspection dot is moved from the center of the bright portion or the dark portion as shown by the symbol (B).

The operations of steps 101 to 106 are performed after the first vertical synchronizing signal is output and before the second vertical synchronizing signal is output. When the second vertical synchronization signal is output, the digitized video signal is converted from the frame memory (7) to the binary counter (8).
Is sent to the display (12), and the still image of the tablet (T) taken first is displayed (step 108). At the same time, the set inspection dot (C) is displayed. Next, it is checked whether or not a re-teaching instruction has been issued (step 109). If not, the process proceeds to step 110. In step 110, it is checked whether or not an instruction to complete the teaching has been issued. If not, the process returns to step 108, and the display of the still image of the tablet (T) captured first is continued. During this time, a person checks the still image of the tablet (T), and if there is a defective product with an abnormal surface or the symbol (M)
If is tilted, re-teaching is instructed. When re-teaching is instructed, step 10
The process returns from 9 to step 101, and after the operations of steps 101 to 107 are performed again, the operation of step 108 is repeated. As a result of checking the still image of the tablet (T), if the product is a non-defective product having no abnormality on the surface and has the standard posture in which the symbol (M) is not inclined as shown in FIG. 5, an instruction to complete teaching is issued. When the instruction of teaching completion is given, step 111
The inspection dot and the binarized non-defective data for the inclined posture are set. That is, the frame memory
By mathematically processing the digitized video data stored in (7), the tablet (T) is rotated leftward (counterclockwise) as shown in FIG. Data and rotation data representing the tilt posture rotated right (clockwise) as shown in FIG.
Step 105 is performed for the rotation data representing each inclination posture.
The same setting of x-axis and y-axis, the setting of the inspection dot (C) as in step 106, and the storage of the inspection dot position and binarized non-defective data as in step 107 are performed. In this case, for both the left and right rotations, inspection dots and binarized non-defective data are set for a plurality of inclined postures at different rotation angles. Step 111
Is completed, the operation in the teaching mode ends. Thereby, relative to the standard attitude and a plurality of tilted attitudes, the relative position of the inspection dot (C) in the symbol inspection window (W0) using the x-axis and the y-axis as reference coordinate axes and the binary value of each inspection dot (C) Non-defective signal data is stored.

Among the above operations in the teaching mode, the selection of the teaching mode, the instruction of the re-teaching and the instruction of the completion of the teaching are manually performed by a person.
Other operations are automatically performed by a command from the CPU (11). Further, the binarization of the digitized video data by the CPU (11) may be performed collectively at an appropriate time, for example, after the processing of step 104 is performed, or may be performed each time for a necessary unit dot. You may.

When the teaching is completed, the normal operation of the printing press is started. Then, during the operation of the printing press, the appearance defect of the tablet (T) as described above is inspected. FIG.
An example of an inspection process that is repeatedly performed each time the pocket (2) holding the printed tablet (T) reaches the inspection position is shown.

In FIG. 10, when the pocket (2) comes to the inspection position, an image is inputted (step 201), and the center position of the tablet (T) just taken is obtained (step 202).
A window correction amount is obtained (step 203), the corrected position information of the symbol inspection window (W0) is stored in the memory (step 204), and the corrected symbol inspection window (W0) is stored.
X-axis and y-axis are set in (W0) (step
205). The processing of steps 201 to 205 is the same as the processing of steps 101 to 105 in the teaching mode,
This is performed between the time when the first vertical synchronization signal is output and the time when the second vertical synchronization signal is output. When the second vertical synchronizing signal is output, the window correction amount is output from the CPU (11) to the window board (9) in order to check the margin inspection window (W1) described later (step 206). Next, the quality of the symbol inspection window (W0) is determined (step 20).
7). This determination is first performed for the standard posture, and then performed sequentially for a plurality of inclined postures. If it is determined that there is no abnormality in any of the postures, it is determined that there is no abnormality in the symbol inspection window (W0) at that point, and the determination ends. If it is determined that all postures are abnormal, the symbol inspection window (W0)
Is determined to be abnormal, and the determination ends. In addition,
In the determination of the pass / fail of the symbol inspection window (W0), as in the case of the above-described teaching, the binarized video data obtained by binarizing the digitized video data in the frame memory (7) is examined to determine whether the unit dot is a bright portion. Or a dark part is determined.

The determination for the standard posture is performed as follows. First, in the corrected symbol inspection window (W0),
A plurality of inspection dots (C) are set such that the relative coordinate values using the x-axis and the y-axis as reference coordinate axes match the relative coordinate values of the inspection dots with respect to the standard attitude stored in the memory. Next, the binarized video data and the binarized non-defective data for the standard attitude stored in the memory of the CPU (11) are compared for all the inspection dots (C). Be counted. When comparing the binarized video data of the inspection dot (C) with the binarized non-defective data, even if the binarized video data of the inspection dot (C) does not match the binarized non-defective data, the inspection is performed. If any of the binarized video data of the four upper, lower, left and right unit dots adjacent to the dot (C) matches the binarized non-defective data, the binarized video data of the inspection dot (C) is binarized non-defective. Suppose it matches the data. When the number of inspection dots where the binarized video data and the binarized non-defective data do not match is larger than a predetermined allowable value, it is determined that there is an abnormality in the symbol inspection window (W0). Determines that there is no abnormality. The determination for each inclined posture is performed in the same manner using the relative coordinate values of the inspection dots for the respective inclined postures and the non-defective binarized signal data.

When the size of the symbol (M) in the symbol inspection window (W0) is almost the same as that at the time of teaching, and there is no chipping of the relatively large symbol (M) and no print stain (defective shape),
The number of the inspection dots (C) in which the binarized video data and the binarized non-defective data do not match is 0 or very small. Therefore, in such a case, it is determined that there is no abnormality in the symbol inspection window (W0). Also, even if the symbol (M) is slightly thicker or thinner than at the time of teaching, if there is no defective shape of the symbol (M), similarly, it is determined that there is no abnormality in the symbol inspection window (W0), There is no case where an object having no shape defect is erroneously determined to be abnormal.
On the other hand, if there is a shape defect of the symbol (M), the symbol (M)
The number of inspection dots (C) in which the binarized video data and the binarized non-defective data do not match each other due to chipping or printing stains increases. Therefore, in such a case, it is determined that there is an abnormality in the symbol inspection window (W0). In the case where chipping of the symbol (M) and printing smear occur simultaneously, similarly, it is determined that there is an abnormality in the symbol inspection window (W0), and it is not erroneously determined that there is no abnormality.

The position of the tablet (T) held in the pocket (2) when the inspection position is reached varies depending on the tablet (T). In the above embodiment, the position of the symbol inspection window (W0) is corrected in accordance with the actual position of the tablet (T) at the time of inspection, and the x-axis passing through the upper end position of the dark portion in the symbol inspection window (W0). Since the position of the inspection dot (C) is represented by relative coordinate values with the y-axis passing through the left end position as the reference coordinate axis, the quality of the symbol inspection window (W0) can be checked even if the position of the tablet (T) is slightly shifted. The determination can be made reliably.

If the binarized video data of the inspection dot (C) is simply compared with the binarized non-defective data with respect to the standard posture, and the quality judgment of the symbol inspection window (W0) is completed, the symbol (M Even if there is no defective shape in ()), if the tablet (T) is slightly tilted, it may be determined that there is an abnormality. But,
In the case of this embodiment, the binarized data of the inspection dot (C) is compared with the binarized non-defective data for the standard posture and a plurality of inclined postures, and if it is determined that there is no abnormality in any posture, It is determined that there is no abnormality in the symbol inspection window (W0), so if the tablet (T) is tilted, a symbol (M) with no shape defect can be mistakenly determined to be abnormal. Is very low.

While the appearance defect in the symbol inspection window (W0) is determined as described above, the binarization counter
In (8), the number of unit dots that are dark portions in the margin inspection window (W1) is counted as follows. When the second vertical synchronizing signal is output, the digitized video data is sequentially sent as digitized video signals from the frame memory (7) to the binarization counter (8), while the binarization counter is sent from the window board (9). Window information is sent to (8) in order. At this time, the window information sent to the binarization counter (8) is obtained by correcting the window information stored in the window memory by the window correction amount sent from the CPU (11). That is, window information corrected so as to match the position of the tablet (T) imaged for inspection is sent to the binarization counter (8). Also, the digitized video data and the window information corresponding to the same unit dot are sent one by one for each unit dot. Therefore, when the digitized video data corresponding to the unit dot in the corrected margin inspection window (W1) is transmitted, window information (“1” indicating that the unit dot is in the margin inspection window (W1)). ") Is sent. The binarization counter (8) binarizes the digitized video data sent from the frame memory (7) to obtain binarized video data. Then, from the window board (9), the margin inspection window (W1)
When window information ("1") indicating that the unit dot is within the
It is checked whether the valued video data is a bright part or a dark part, and if it is a dark part, the count value is increased by one. Therefore, the count value after all the digitized video data has been sent from the frame memory (7) indicates the number of unit dots that are dark portions in the corrected margin inspection window (W1). When the counting is completed, the count value is output to the CPU (11).

When the CPU (11) determines whether or not the symbol inspection window (W0) is good or not in step 207, the CPU (11) uses the count value input from the binarization counter (8) to store the symbol in the margin inspection window (W1). The appearance defect is determined (Step 20)
8). That is, when the count value is larger than the predetermined allowable value, it is determined that there is an abnormality in the margin inspection window (W1), and otherwise, it is determined that there is no abnormality. When there is no abnormality such as print smear or chipping in the margin inspection window (W1), the number of unit dots, which are dark portions, in the margin inspection window (W1) is zero or very few.
Therefore, by performing the above, it is possible to determine the appearance defect in the margin inspection window (W1).
Next, the above determination result is output. That is, if it is determined that there is no abnormality in both the symbol inspection window (W0) and the margin inspection window (W1), a non-defective signal is output as a determination result otherwise. The process of step 207 ends before the third vertical synchronization signal is output.

As described above, the tablet at the inspection position
Since the position of (T) varies depending on the tablet (T), assuming that the position of the margin inspection window (W1) is not corrected, if the margin inspection window (W1) is set too large, the tablet
When the position of (T) changes, the margin inspection window (W1)
May protrude from the tablet (T). In order to avoid this, it is necessary to set the margin inspection window (W1) small, but this makes it impossible to perform an appearance inspection near the outer periphery of the tablet (T). However, in the case of this embodiment, since the position of the margin inspection window (W1) is corrected to match the position of the actual tablet (T), the margin inspection window (W1) is corrected.
Even if (W1) is set to a large value, the margin inspection window (W1) does not protrude from the tablet (T) when the position of the tablet (T) changes, and the outer appearance close to the outer peripheral edge of the tablet (T) Inspection is possible.

During the inspection, a still image of the tablet (T) is displayed on the display (12) by the digitized video signal sent from the frame memory (7) through the binarization counter (8), A still binary image of the tablet (T) can be displayed based on the binary video signal sent from the conversion counter (8).

[0052]

According to the tablet appearance inspection method of the present invention, as described above, even if the position of the tablet is slightly shifted, it is possible to surely inspect the shape defect of the symbol printed on the tablet surface. Therefore, it is possible to accurately inspect the tablet surface for the presence or absence of poor appearance.

When the number of inspection dots whose binarized video data does not match the binarized non-defective data is larger than a predetermined allowable value, it is determined that there is a defective appearance in the symbol inspection range. The presence or absence can be easily determined.

[0054] The plurality of inclined posture rotated by a predetermined angle a tablet agent from the standard position and the normal position, the binarized good data for each test dots may be set respectively, the binary image data in either orientation When it is determined that there is no appearance defect in the symbol inspection range by comparing the data with the binarized non-defective product data, it is determined that there is no appearance defect in the symbol inspection range. Inspection of poor appearance can be surely performed even when inclined.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a printing press and a tablet appearance inspection apparatus showing an embodiment of the present invention.

FIG. 2 is an enlarged sectional view showing a part of a first tablet supply roll of the printing press.

FIG. 3 is a front view showing an example of a tablet.

FIG. 4 is a front view showing an example of a television image of a tablet.

FIG. 5 is a front view showing an example of a television image of a portion of the symbol inspection window of the tablet (T).

6 is an enlarged front view showing a part of the television image of FIG. 5;

7 is a front view showing another example of a television image of the portion of the sign test window lock agent.

8 is a front view showing still another example of the television image of the portion of the sign test window lock agent.

FIG. 9 is a flowchart illustrating an example of a process in a teaching mode.

FIG. 10 is a flowchart illustrating an example of a process at the time of inspection.

[Explanation of symbols]

 (5) TV camera (T) Tablet (M) Symbol (W0) Symbol inspection window (Symbol inspection area) (C) Inspection dot

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ryohei Du 2-12-13 Okamoto, Higashinada-ku, Kobe (56) References JP-A-2-27239 (JP, A) JP-A 3-270939 (JP, A) JP-A-6-44362 (JP, A) JP-A-3-274153 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/84-21/958 G06T 1 / 00-9/40

Claims (3)

(57) [Claims] 1. A predetermined symbol inspection area including a symbol portion is set on the surface of a tablet on which a symbol is printed, and the symbol inspection area is imaged by a two-dimensional imaging device. The above-described symbol inspection range is equally divided into a plurality of unit dots in the horizontal scanning direction and the vertical scanning direction by the clock signal, and a video signal corresponding to each unit dot is divided into a bright portion and a dark portion by a predetermined threshold value. And processing these binarized video data to check for the presence or absence of an appearance defect in the symbol inspection range of the tablet, wherein a plurality of inspection dots are selected from the unit dots in the symbol inspection range. For each inspection dot, binarized non-defective data indicating whether the inspection dot is a bright portion or a dark portion in the case of a non-defective item is set.
In the method of judging the presence or absence of an appearance defect in the symbol inspection range by comparing the digitized video data with the binarized non-defective data of the inspection dot, in the symbol inspection range,
In the horizontal scanning direction passing through the unit dot which is the dark part at the end
Axis as the horizontal reference axis, and the
The axis in the vertical scanning direction that passes through the unit dot
The horizontal reference axis and the vertical reference axis
The position of each inspection dot is represented by the relative coordinate value used as the reference axis.
Appearance inspection method of a tablet characterized in that to. 2. The symbol inspection area is determined to have a defective appearance when the number of inspection dots whose binary image data does not match the binarized non-defective data is larger than a predetermined allowable value. Item 1. A method for inspecting the appearance of tablets. 3. The position of each inspection dot and binarized non-defective data are set for a standard posture and a plurality of inclined postures obtained by rotating the tablet by a predetermined angle from the standard posture. When it is determined by comparison between the digitized video data and the binarized non-defective data that there is no appearance defect in the symbol inspection range, it is determined that there is no appearance defect in the symbol inspection range. 2. Method for inspecting the appearance of tablets.