JPH0773323A - Character judging device - Google Patents

Abstract

PURPOSE:To provide a character judging device for adjusting a distance between the surface of a work and an image pickup camera corresponding to distortion on the surface of the work on which characters are engraved. CONSTITUTION:A CCD camera 16 for detecting the characters engraved on a metal plate 12 is loaded on a supporting member 24 together with a distance sensor 18. First of all, the distance to the surface of the metal plate 12, where the characters to be judged are engraved, is measured by the distance sensor 18 and the sensor is moved for each character. In this case, the supporting member 24 is made close or away from the surface of the metal plate 12 by turning a ball screw 28 based on the distance detected by the distance sensor 18, and the distance is adjusted so as to be a prescribed distance. Therefore, the quality of characters to be judged can be exactly judged without being affected by distortion on the surface of the metal plate 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention takes an image of a character imprinted on an object with a photographing camera at a position separated from the object by a predetermined distance, and judges the quality of the imprinted character based on the imaging. The present invention relates to a character determination device.

[0002]

2. Description of the Related Art Conventionally, a series of numbers, characters, etc. are stamped on the body of an engine or a vehicle body in order to discriminate the production time, type and the like. Therefore, in order to confirm whether or not the characters are accurately engraved on these works, the character information is read by an imaging camera, and the inspector confirms the imaged image on the screen so that the engraved character is I was inspecting.

However, according to this processing method, the burden on the inspector is large, so the image data of the imaged stamped character is binarized and pattern matching is performed with the preset reference character data. A technique has been proposed which is configured to detect a defective character by checking whether or not the size and thickness of the character are appropriate, the presence or absence of a break point, and the like.

[0004]

However, in general, since the depth of the recessed portion forming the engraved character is extremely small, distortion of the surface of the object on which the character is engraved affects the imaged image. Easy to get out. For example, although the characters are engraved in an appropriate size, the surface of the object is distorted, so the distance between the imaging camera and the object deviates slightly from the desired distance, and the image data of the engraved character is not captured. It will be different from the size of the preset data. As a result, the engraved character may be determined to be defective during pattern matching.

The present invention has been made to solve this type of problem, and adjusts the distance between the surface of an object on which characters are engraved and the image pickup camera in accordance with the distortion of the surface of the object. It is an object of the present invention to provide a character determination device capable of reading character information using an imaging camera at the position.

[0006]

In order to achieve the above-mentioned object, the present invention compares preset character data with image information of the character imprinted on the surface of the work, and A character determination device for determining pass / fail of size, thickness, etc., which is an image pickup means for picking up an image of a marked character, and a distance detecting means for detecting a distance between the surface of a work on which the character is marked and the image pickup means. A first displacing means for displacing the imaging means and the distance detecting means and the surface of the work relatively parallel to each other at a predetermined distance, and the imaging means and the distance detecting means on the surface of the work. A second displacing means for moving toward or away from the work surface of the image pickup means and the distance detecting means when the distance detected by the distance detecting means is different from a predetermined distance set in advance. Against As the distance is a predetermined distance second
It is characterized in that the displacement means is biased.

[0007]

In the character determining apparatus according to the present invention, the image pickup means is positioned on the character imprinted on the work by the first displacement means. At that time, the distance detecting means detects the distance from the surface of the work, and the second displacing means displaces the imaging means to a predetermined position so that the distance becomes a predetermined value. Therefore, it is possible to prevent any imprinted character imaged by the imaging means from being imaged at a fixed distance and erroneously determining that the imprinted character is improper in size, It can be determined accurately.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A character determining apparatus according to the present invention will be described in detail below with reference to the accompanying drawings, with reference to the preferred embodiments.

FIG. 1 is a block diagram showing the main construction of an embodiment to which the character judging device of the present invention is applied, and an example of judging the quality of a character imprinted on a metal plate as a work will be described. To do.

In FIG. 1, reference numeral 10 indicates a character determination device according to the present invention. The character determination device 10 is provided at a position where a metal plate 12 engraved with a character to be determined is detachably attached to a predetermined position on the surface and a position facing a character string to be determined in order to image the character to be determined. And a distance sensor 18 for measuring the distance between the CCD camera 16 and the metal plate 12 with a laser beam.
A sequencer 20 for controlling the position of the CCD camera 16 based on the output of the distance sensor 18 in order to sequentially read each character to be judged forming a character string to be marked engraved on the metal plate 12, and a CCD The image processing unit 22 basically receives an image signal of the character to be judged read by the camera 16 and judges the quality of the character to be judged.

The CCD camera 16 and the distance sensor 1
8 is attached to the support member 24. The support member 24
Is a metal plate 1 for changing the distance between the guide member 26 movably mounted in the direction of the character string to be judged (hereinafter referred to as X direction) and the CCD camera 16 and the surface of the metal plate 12.
It is configured to be displaceable in the X direction and the Z direction by a ball screw 28 that advances and retracts the guide member 26 in a direction orthogonal to the extending direction of 2 (hereinafter referred to as the Z direction). The distance sensor 18 detects the distance between the surface of the metal plate 12 and the CCD camera 16 based on the output of the distance sensor 18.
Connected to 0. The CCD camera 16 is connected to an image processing unit 22 which determines whether or not the character to be judged is accurately marked based on the image information of the character to be judged. The image processing unit 22 stores the determination reference data and is connected to the arithmetic processing unit 32 that outputs the determination result. The distance calculator 3
0 and the arithmetic processing unit 32 are connected to the sequencer 20, and based on the output information thereof, the support member 24 and the ball screw 28.
Is driven to displace the support member 24 to a predetermined position. The sequencer 20 is also connected to the external input device 33.

By the way, the CCD camera 16 and the distance sensor 18 are installed on the support member 24 in the X direction with one character space between them being separated. Therefore,
While the CCD camera 16 is picking up an image of a character to be judged, the distance sensor 18 can detect the distance of the next character to be judged from the metal plate 12.

The arithmetic processing section 32 has a reference character data information memory 34 inside and is connected to an external host computer 35. In the reference character data information memory 34, line drawing data of the reference character corresponding to the character to be determined, range information corresponding to the size of the character, division point information in the reference character pattern having the same shape as the stencil printing, and thinning. The number of end points that is the number of ends in the reference character, the number of branch points that is the number of contact points with straight lines and curves in the thinned reference character, the allowable difference information for the reference character, and the reference character Character thickness information including the thickness in the window is stored.

In the image processing section 22, as shown in FIG.
Out-of-range removal circuit 3 for removing the determined character image data that goes out of the range defined by the character range information for the determined character
6, a size determination circuit 38 for determining whether the size of the character to be determined is within a predetermined range, an inclination determination circuit 40 for determining whether the inclination of the character to be determined is within a predetermined range, and the determination target A division number determination circuit 42 for determining whether or not the number of divisions of a character is a predetermined number, a binarization circuit 44 for binarizing image data of the determination target character, and thinning the determination target character based on the binarized data. Thinning circuit 46, end point number information for reference characters, end point number corresponding to branch point number information, end point number of branch point number and end point of thinned character image to be judged, and end point number judgment for judging whether or not the branch point number matches A circuit 48, a comparison circuit 50 for comparing the thinned character to be judged with a thinned reference character, a difference judgment circuit 52 for judging whether the output of the comparison circuit 50 is within an allowable difference range, and Judgment character thickness is within the specified range And a thickness determination circuit 54 determines whether.

Based on the program stored in the program memory, the operation of the present embodiment configured as described above will be described with reference to FIG.
And it demonstrates according to the flowchart of FIG.

A signal indicating that the metal plate 12 is installed at a predetermined position on the base 14 is transmitted from the host computer 35 monitoring the production line to the arithmetic processing section 32. As a result, a displacement signal is output from the sequencer 20 to the support member 24, and the distance sensor 18 is positioned on the character "A" to be judged. By the distance sensor 18, the metal plate 1
The distance between the distance sensor 2 and the distance sensor 18 is detected by the laser beam, and the distance calculation unit 30 detects the difference between the distance and the predetermined distance based on the signal. Based on this difference, the displacement amount of the guide member 26 in the Z direction is output to the sequencer 20. Next, a displacement signal for displacing one character of the character string to be determined is derived from the sequencer 20 to the support member 24, and a signal for rotating the ball screw 28 by the displacement amount is derived. It As a result, the support member 2
The CCD camera 16 mounted on the No. 4 is driven by one character adjacent in the direction of the character string to be judged, and reaches a position facing the first character position of the character to be marked imprinted on the metal plate 12. Hereinafter, a case where the first character to be judged in the character string to be judged is “A” and the quality of the character “A” to be judged is judged will be described as an example.

The CCD camera 16 set at the above position
The character “A” to be judged is picked up by, the image information based on the picked-up image is read as judged character image data, and stored in the work area (step S1). Here, it is assumed that the character “A” to be judged is as shown in FIG. 5 and the broken line portion is missing. Following step S1, the judgment character image data output from the CCD camera 16 is subjected to preprocessing such as smoothing to remove noise (step S2), and subsequently the character range information is set to the reference character data information. The judged character image data portion which is read from the memory 34 and is outside the character range designated by the character range information is removed (step S3). Step S
By execution of 3, the judged character image data which is outside the range defined for the judged character is removed.

Therefore, as shown in FIG. 5, a rectangular body (see the solid line) circumscribing the character to be judged is set in the character data to be judged within the character range, and this is used as the character size information of the reference character data information memory 34. It is determined whether or not the size of the character to be judged is within a predetermined range by comparing it with the rectangular body set in (step S4). If it is outside the predetermined range, it is determined to be defective (step S5). If it is within the predetermined range in step S4, subsequently, the inclination angle α with the rectangular body (see the chain double-dashed line) circumscribing the character to be judged along the X direction and the Y direction parallel to the frame of the image data is within the predetermined range. It is determined whether it is within (step S6). If it is outside the predetermined range, it is determined to be defective (step S7). When the inclination angle α is outside the predetermined range, it means that the character is inclined and engraved when the character to be judged is embossed.

Subsequent to step S6, division point number information, end point number information and branch point number information of the reference character pattern corresponding to the character to be judged are read from the reference character data information memory 34 and temporarily stored in the work area. (Step S
8). As shown in FIG. 6B, the reference character of this example has three end points (P1, P4, P5) and three branch points (P2, P3, P6).

It is checked whether the division number of the reference character image corresponding to the reference character data read in step S8 matches the division number of the determined character image corresponding to the determined character image data (step S8). S9). here,
It is assumed that the number of divisions of the character image to be judged is checked if the character on the bottom surface of the stamp used for embossing has the same character shape as that imprinted by the stencil, otherwise, step S8 and There is no problem even if step S9 is omitted.

If it is determined in step S9 that the division scores do not match, the character to be determined is determined to be defective (step S10). Usually, when the divided points do not match, it means that there is a break in the character to be judged, or when the wrong character to be judged is imprinted. When it is determined in step S9 that the number of divisions is the same, the judgment character image data is binarized (step S11) following step S9, and the binarized judgment character image data is thinned. It is processed (step S12). Here, the thinning process is performed to detect the number of end points and the number of branch points in the character to be determined.

Following step S12, whether or not the number of end points of the character image to be judged based on the thinned character image data and the number of end points of the reference character image match, and the thinned character image data It is checked whether or not the number of branch points of the character image to be determined based on the above-mentioned number and the number of branch points of the reference character image match (step S13).

When it is determined in step S13 that the number of end points or the number of branch points do not match, the character to be determined is determined to be defective (step S14). When the number of end points or the number of branch points do not match, it is usually the case where a part of the character to be judged is missing due to a flaw on the bottom surface of the marking.

When it is determined in step S13 that the number of end points and the number of branch points are the same, the character to be judged corresponding to the portion surrounded by the branch points P2, P3, P6 and the end point P5 of the reference character in FIG. 6 (b). Filling processing is performed to fill in the portion (step S15). Following step S15, the reference character data is line-drawn and rendered (step S16). The standard characters that have been line-drawn and rendered are as shown in FIG. A determined character image based on the determined character image data captured in step S1 subsequent to step S16;
A logical product operation is performed on the reference character image that has been line-drawn and rendered (see FIG. 6) (step S17). Here, since a part of the character image to be determined is filled by the filling process, the phase matching when performing the AND operation becomes easy.

The result of the logical product operation in step S17 is as shown in FIG. 6 (c). Subsequent to step S17, the logical operation result (see FIG. 7B) is subtracted from the reference character image (see FIG. 7A) that has been line-drawn and rendered, and the difference between the two (see FIG. 7C). )) Is detected (step S18). Based on the difference detected in step S18, it is checked whether the character to be judged is within the allowable difference with respect to the reference character (step S19).

When the difference detected in step S19 is out of the allowable difference range, the character to be judged is judged to be defective (step S20). When it is determined to be defective in step S20, there is a chip in the embossed character, and the chip is larger than the allowable range. Step S1
When it is determined that the difference detected in 8 is within the range of the allowable difference, the window character thickness determination routine is executed subsequent to step S19.

The character thickness information including the window, which is stored in the reference character data information memory 34, is stored for a portion to which force is applied during embossing, and includes, for example, end points and branch points as shown in FIG. Stored for parts.

If the character thickness determination routine is entered, one of the windows is selected, and it is checked whether the thickness of the portion of the character image to be determined corresponding to the selected window is within a predetermined range (step S21). , S22). Here, the horizontal thickness is checked for the windows W1 and W4, the vertical thickness is checked for the window W5, and the vertical and horizontal thicknesses are checked for the window W2. .

If it is determined in step S22 that the thickness of the character in the window is not within the predetermined range, the character to be determined is determined to be defective (step S2).
3). If the judgment result in step S23 is defective, it means that the character to be judged is faint.

Then, steps S21 and S22 are executed until all windows are selected, and when selected over all windows, it is determined that the character to be judged is not defective (step S24).

During the series of image processing, the distance sensor 18 is located on the character "7" to be judged adjacent to the character "A" to be judged, and the metal to which the character "7" is marked is engraved. The distance between the surface of the plate 12 and the distance sensor 18 is detected.

Therefore, if it is determined in step S24 that the character "A" to be judged is not defective, a displacement signal is derived from the sequencer 20 to the ball screw 28 and the support member 24, and the character "7" to be judged. The CCD camera 16 is driven to the position corresponding to, and the quality of the next character to be judged is judged as in the case of the first character.

That is, in the character judging device 10, as shown in FIG. 9, even if the surface of the metal plate 12 on which the character to be judged is engraved is formed in a wavy shape, the distance sensor 1
The distance from the surface of the metal plate 12 where the character to be judged is engraved is detected by 8, and the support member 24 is displaced in the Z direction by the rotation of the ball screw 28 and adjusted to a predetermined distance. For example, if the surface of the metal plate 12 is as shown in FIG. 9, the supporting member 24 is displaced downward so that the CCD camera 16 and the surface of the metal plate 12 in the portion of the character "7" to be judged are separated. The distance is maintained at a predetermined distance.

As a result, the metal plate 1 is used when the size and thickness of the character to be judged are detected in the judgment of the character to be judged.
The distance between the surface of 2 and the CCD camera 16 differs for each character to be judged, and the size of the character to be imaged differs, which does not affect the judgment result. Therefore, the quality of the character to be judged can be accurately judged.

[0035]

According to the character determining device of the present invention, the following effects can be obtained.

That is, the image pickup means is positioned on the character imprinted on the work by the first displacement means. At that time, the distance detecting means detects the distance from the surface of the work, and the second displacing means displaces the imaging means to a predetermined position so that the distance becomes a predetermined value. Therefore, it is possible to prevent any imprinted character imaged by the imaging means from being imaged at a fixed distance and erroneously determining that the imprinted character is improper in size, It can be determined accurately.

Moreover, since the CCD camera which is the image pickup means and the distance sensor which is the distance detection means are formed so as to be spaced apart from each other by the distance corresponding to the adjacent character of the character string to be judged, a certain character is read by the CCD camera. During the image pickup, the distance to the surface of the work can be detected by the distance sensor for the character to be determined next, and the determination can be performed efficiently.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a character determination device according to the present invention.

FIG. 2 is a main part configuration diagram of a character determination device according to the present invention.

FIG. 3 is a flowchart showing an image processing method of the character determination device according to the present invention.

FIG. 4 is a flowchart showing an image processing method of the character determination device according to the present invention.

FIG. 5 is a diagram showing a method for detecting a character size and a character inclination in the character determination device according to the present invention.

FIG. 6 is an explanatory diagram showing a character determination method performed by the character determination device according to the present invention.

FIG. 7 is an explanatory diagram showing a character determination method performed by the character determination device according to the present invention.

FIG. 8 is an explanatory diagram of setting windows in the character determination device according to the present invention.

FIG. 9 is an explanatory diagram of a surface shape of a metal plate in the character determination device according to the present invention.

[Explanation of symbols]

10 ... Character determination device 12 ... Metal plate 16 ... CCD camera 18 ... Distance sensor 20 ... Sequencer 22 ... Image processing unit 24 ... Support member 26 ... Guide member 28 ... Ball screw 30 ... Distance calculation unit

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Shigeru Ichikawa 1-10-1 Shin-Sayama, Sayama-shi, Saitama Prefecture Inside the Sayama Plant, Saitama Works, Honda Motor Co., Ltd. 10-1 Honda Motor Co., Ltd. Saitama Plant Sayama Factory

Claims (2)

[Claims] 1. A character determination device which compares preset character data with image information of a character imprinted on the surface of a work and judges the quality, such as size and thickness of the imprinted character. An image pickup means for picking up the imprinted characters, a distance detecting means for detecting a distance between the surface of the work on which the characters are imprinted and the image pickup means, and the image pickup means, the distance detecting means and the surface of the work. A first displacing means for relatively and parallelly displacing at a predetermined distance from each other, and a second displacing means for moving the image pickup means and the distance detecting means toward or away from the surface of the work, When the distance detected by the distance detecting means is different from a predetermined distance set in advance, the second displacement means is biased so that the distance between the imaging means and the distance detecting means with respect to the work surface becomes the predetermined distance. Character determination apparatus characterized and. 2. The apparatus according to claim 1, wherein the image pickup means includes a CCD camera, the distance detection means includes a distance sensor, and the CCD camera and the distance sensor correspond to a character interval of a character string to be determined. A character determination device characterized by being separated from each other.