JPH10171975A - Pattern reader - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correctly read a pattern that is recessedly provided on a measured surface that has gloss. SOLUTION: This device is provided with a conveyor 13 which carries packages 10, a sensor 14 which detects the packages 10 that are carried by the conveyor 13, a light irradiating part 15 by which the packages 10 are irradiated with a scattered light and a camera 16 which reads a stamped character 12 that is formed on a measured plane 11 of the packages 10. The part 15 has a strobe light source that is instantly turned on and an optical diffusion plate 26 that has 70% diffusion degree D. The camera 16 is arranged at a regular reflection position with the part 15 against the measured surface 11 of the packages 10 that are carried by the conveyor 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern reading apparatus, and more particularly, to a pattern reading apparatus for reading a pattern provided on a surface to be measured having gloss.

[0002]

2. Description of the Related Art For example, a package for packaging a product is stamped with a pattern consisting of numbers and alphabets indicating the lot number, manufacturing date, expiration date, etc. of the product (hereinafter referred to as "lot number, etc."). ing. At the time of manufacturing a product, a package of the product continuously supplied from the previous process is imaged by a reading means such as a CCD camera, and the lot number and the like are inspected.

[0003] As one type of pattern for displaying these lot numbers and the like, there is a pattern generally called an engraved character. This engraved character is a pattern formed of fine concave grooves having a line width of 0.5 mm or less formed on the surface of the package.

[0004]

When the lot number and the like are formed by the above-described engraved characters, there arises a problem that the lot number and the like cannot be accurately read in the inspection process of the lot number and the like. This is considered to be due to the following reasons.

That is, at the time of reading a lot number or the like, a light is irradiated from a light irradiating means to a measured surface of a package in which the lot number or the like is recessed, and reflected light from the measured surface is read by a CCD camera or the like. To read. At this time, the surface of the package is formed of a glossy mirror-like printing surface. For this reason, unless the light irradiating means and the reading means are arranged at a regular reflection position with respect to the surface to be measured, light reflected regularly on the surface to be measured does not enter the reading means. Are arranged at regular reflection positions with respect to the surface to be measured.

On the other hand, reading of a lot number or the like is generally performed on a package continuously conveyed by a belt conveyor or the like. For this reason, the measured surface of each package from which the lot number or the like is read has a minute angle error.

At this time, in the configuration in which the light irradiation means and the reading means are arranged at the regular reflection position, if the angle of the surface to be measured is slightly changed, the light is regularly reflected by the mirror-like surface to be measured, and the reading means is reflected on the reading means. The incident reflected light also changes. Further, the irradiation direction of the reflected light reflected by the engraved character portion on the measured surface also changes due to a slight change in the angle of the measured surface. For this reason, the image read by the reading unit becomes unstable, and the reading of the lot number or the like cannot be performed accurately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and has as its object to provide a pattern reading apparatus capable of accurately reading a pattern provided on a surface to be measured having gloss.

[0009]

According to the present invention, there is provided a pattern reading apparatus for reading a pattern provided on a surface to be measured having a gloss, comprising: a light source; the light source; A light diffusing plate disposed between the light irradiating means and the regular reflection position, and a light irradiating means for irradiating the measured surface with scattered light. And a reading means provided.

According to a second aspect of the present invention, there is provided a pattern reading apparatus for reading a pattern recessed on a glossy surface to be measured, wherein the transporting device transports the object having the surface to be measured. Means, a detecting means for detecting the object to be measured conveyed by the conveying means, a strobe light source which is turned on instantaneously based on a detection signal of the detecting means, a surface to be measured of the strobe light source and the object to be measured. A light diffusing plate disposed in an optical path between the light source and the light irradiating means for irradiating the surface to be measured with scattered light; And reading means arranged at the position.

[0011]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram of a character inspection apparatus to which a pattern reading apparatus according to the present invention is applied.
FIG. 4 is an explanatory view showing the arrangement of the optical system.

This character inspection apparatus is for inspecting the engraved characters 12 formed on the package 10 for missing characters, printing errors, missing characters, misalignments, and the like. Conveyor 1 for transporting
3, a sensor 14 for detecting the package 10 conveyed by the conveyor 13, a light irradiator 15 for irradiating the package 10 with light, and an engraved character 12 formed on the measured surface 11 of the package 10. C for reading
A CD camera 16 and a control unit 17 are provided.

The surface of the package 10 is formed from a glossy printed surface. A lot number or the like formed by combining numbers and alphabets is formed on the side surface by engraved characters 12. Each of the engraved characters 12 has a size of several mm square.
The line width of the concave groove forming No. 2 is about 0.3 mm.

The conveyor 13 places a plurality of packages 10 on an endless belt 23 rotated by the drive of a drive motor 22, and conveys the packages 10 at a constant speed in the direction of arrow A. Then, the package 10 transported by the conveyor 13 indicates that the package 10 has reached a predetermined position.
It is detected by a sensor 14 having a light emitting and receiving unit.

As shown in FIG. 2, the light irradiation section 15 has a strobe light source 24, a cover 25, and a light diffusion plate 26. The strobe light source 24 includes a light emitting unit such as a xenon tube and a strobe main body (not shown).
It is configured to light up instantaneously for a time of μs. Further, the cover 25 is provided with the light diffusing plate 2 installed at the opening thereof.
6 is configured to be supported.

As the light diffusing plate 26, for example, a plate that combines glass fiber and polycarbonate resin and diffuses light due to a difference in refractive index between the two materials is used. The light diffusion plate 26 has a diffusion degree D of 70%.
Are used.

The "diffusion degree D" described in the present specification is, as shown in the following equation (1), 20 degrees with respect to the normal of a light beam irradiated from the normal direction to the light-transmitting material. It refers to a value obtained by multiplying the reciprocal of the luminance B ₀₅ mean value of 5-degree direction between the luminance B ₂₀ and 70 degree directional luminance B ₇₀ direction.

D = [(B ₂₀ + B ₇₀ ) / 2] · (1 / B ₀₅ ) (1)

The CCD camera 16 is for reading the engraved characters 12 on the surface 11 to be measured of the package 10.
The light irradiation unit 15 and the regular reflection position are arranged with respect to the surface 11 to be measured. In other words, when inspecting the engraved character 12, as shown in FIG. 2, the angle between the optical axis of the light irradiation unit 15 and the normal to the surface 11 to be measured, and the CCD camera 16
Is the same angle θ between the optical axis and the normal to the surface 11 to be measured. The angle θ is preferably small to improve the contrast and to reduce the amount of distortion when reading the engraved character 12.

When the engraved character 12 on the glossy surface 11 to be measured is photographed by the CCD camera 16, the light from the light irradiating section 15 is specularly reflected on the surface 11 to be measured. Since irregular reflection occurs in the portion and the reflected light hardly reaches the CCD camera 16, the engraved character 12 is detected as a dark image.

The control unit 17 includes a ROM, a RAM (not shown)
And is controlled by a microcomputer including a CPU and a CRT monitor 31, counter display units 32 and 33, an input unit 34, and an output line 35.

Next, the operation of the character inspection apparatus to which the pattern reading apparatus according to the present invention is applied will be described. FIG.
5 is a flowchart showing an operation of inspecting the engraved character 12 on the package 10 by the character inspection device.

First, it is necessary to register a master pattern as basic data when performing character inspection. This registration is performed as follows.

First, with the conveyor 13 stopped,
The package 10 is placed at the inspection position of the engraved character 12.
As used herein, the “inspection position” refers to the angle between the optical axis of the light irradiation unit 15 and the normal to the surface 11 to be measured, the optical axis of the CCD camera 16 and the surface 11 Is a regular reflection position at which the angle formed by the normal with the same angle is the same angle θ.

In this state, the strobe light source 24 in the light irradiation section 15 is turned on instantly (step S1).
The CCD camera 1 disposed at a regular reflection position with the light irradiating unit 15 reflects the light reflected from the measured surface 11 of the package 10.
6. An image is taken by step 6 (step S2). CCD camera 16
Are subjected to image processing such as gray processing (multi-value processing) in the control unit 17, and are registered by being stored in a storage unit in the control unit 17 (step S3).

At this time, the strobe light source 24 and the surface to be measured 1
Since the light diffusing plate 26 is disposed between the light-emitting device 1 and the light-emitting device 1, the surface 11 to be measured is irradiated with scattered light. Therefore, the light diffusion plate 26 plays a role of a secondary light source, and even if a slight angle error occurs on the surface 11 to be measured, the reflected light that is incident from the surface 11 to be measured by the CCD camera 16. Is stable. In addition, since the light diffusion plate 26 having a diffusion degree D of 70% is particularly used, the engraved character 12 having a narrow groove width and particularly difficult to detect can be accurately identified.

Next, the engraved characters 12 of the plurality of packages 10 conveyed by the conveyor 13 are continuously inspected.
Note that a plurality of types of master patterns may be registered in advance by repeating steps S <b> 1 to S <b> 3 before checking the engraved character 12.

First, the drive motor 22 is driven by a command from the control unit 17, and a plurality of packages 1 are
0 is conveyed (step S4). First package 10
Is transported to the inspection position, this is detected by the sensor 14 (step S5), and the strobe light source 24 is turned on instantly (step S6). Then, the reflected light from the measured surface 11 of the package 10 is imaged by the light irradiating section 15 and the CCD camera 16 disposed at the regular reflection position (Step S).
7).

The image photographed by the CCD camera 16 is subjected to image processing such as gray processing (multi-value processing) in the control unit 17 and then compared with the previously registered image. (Steps S8 and S9). This comparison processing is performed by a known method such as a pattern matching method.

At this time, the light diffusion plate 26 is disposed between the strobe light source 24 and the surface 11 to be measured, as in the above-described registration of the master pattern. Even if a slight angle error occurs on the surface 11 to be measured,
The reflected light incident by the CD camera 16 is stable.
The light diffusion plate 26 has a diffusion degree D of 70% in particular.
, It is possible to accurately identify the engraved character 12 having a narrow groove width and particularly difficult to detect.

Further, in this embodiment, a strobe light source 24 which is turned on instantaneously in the light irradiating section 15 is used, and the engraved character 12 on the package 10 is illuminated by the strobe light source 24 and photographed by the CCD camera 16. Therefore, even when the engraved character 12 of the package 10 being moved is inspected, the inspection can be performed accurately without causing the image flow. Therefore, a large number of packages 10 can be inspected efficiently.

By using the strobe light source 24, it is possible to obtain a light amount necessary for reading by the CCD camera 16 while the light irradiation unit 15 is relatively small. At this time, by combining the strobe light source 24 close to the point light source with the light diffusing plate 26, it is possible to efficiently irradiate the measured surface 11 with diffused light with a simple configuration.

After performing the comparison process, the number of good and bad is counted (steps S10 and S11). The count value is displayed on the counter display unit 3 of the control unit 17.
2, 33. An error is displayed for the defective package 10 (step S1).
2) If necessary, a signal is given to the elimination device for eliminating the defective package from the conveyor 13 through the output line 35.

When the required number of packages 10 have been inspected by repeating the above-described operations of steps S5 to S12 (step S13), the drive motor 22 is stopped (step S14), and the inspection processing is terminated.

In the above description, the case where the engraved character 12 formed on the glossy package 10 is read and inspected by the character inspection device has been described. It is also possible to read and inspect the normal seal characters printed on the. That is, a light irradiating section 15 for irradiating the measured surface 11 with scattered light, and the CCD camera 1 disposed at a regular reflection position with the light irradiating section 15 on the measured surface 11.
According to 6, even if a slight angle error occurs on the measured surface 11 of the package 10 conveyed by the conveyor 13, it is possible to accurately identify the imprinted character as well as the engraved character 12. . Therefore, both a stamp character and a stamp character can be inspected by a single character inspection device.

In the above-described embodiment, the light diffusion plate 26 having a diffusion degree D of 70% is used. The value of the diffusion degree D depends on the shape of the light source and the cover 25 of the light irradiation section 15. Can be appropriately changed depending on the shape, surface treatment and the like. For example, when the surface of the cover 25 is a diffusion surface, a light diffusion plate having a lower diffusion degree D can be used. However, in order to accurately identify the engraved character 12 having a small groove width and difficult to detect, the light diffusing plate 2
The diffusion degree D of the light beam in No. 6 is preferably 20% or more.

In the above-described embodiment, the present invention is applied to the case where the engraved character 1 formed on the surface of the package 10 is used.
2 has been described, the present invention can be applied to various pattern reading devices for reading a pattern that is recessed on a glossy surface to be measured.

[0038]

According to the first aspect of the present invention, there is provided a light source and a light diffusion plate disposed between the light source and the surface to be measured to irradiate the surface to be measured with scattered light. Since the light irradiating means and the reading means arranged at the specular reflection position with the light irradiating means for the surface to be measured, even when a slight angular error occurs on the surface to be measured, It is possible to accurately read a pattern recessed on a glossy surface to be measured.

According to the second aspect of the present invention, the conveying means for conveying the object to be measured having the surface to be measured, the detecting means for detecting the object to be measured conveyed by the conveying means, A strobe light source that is turned on instantaneously based on a detection signal of the means, and a light diffusion plate disposed in an optical path between the strobe light source and the surface to be measured of the device to be measured, and irradiates the surface to be measured with scattered light. Light irradiating means, and light irradiating means for the surface to be measured and reading means disposed at the regular reflection position, so that even if a slight angular error occurs on the surface to be measured. Thus, it is possible to accurately read a pattern recessed on a glossy surface to be measured.

At this time, since the strobe light source which is turned on instantaneously is used for the light irradiating means, even when reading the pattern of the object to be measured which is being conveyed by the conveying means, there is no image flow. Reading can be performed accurately. Therefore, it is possible to read efficiently. In addition, by using a strobe light source, it is possible to obtain a light amount necessary for reading by the reading unit while making the light irradiation unit relatively small, and furthermore, by combining a strobe light source close to a point light source with a light diffusing plate. In addition, it is possible to efficiently irradiate the surface to be measured with diffused light with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a character inspection device to which a pattern reading device according to the present invention is applied.

FIG. 2 is an explanatory diagram showing an arrangement of an optical system of the pattern reading apparatus according to the present invention.

FIG. 3 is a flowchart illustrating an operation of inspecting an engraved character by the character inspection device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Package 11 Surface to be measured 12 Engraved character 13 Conveyor 14 Sensor 15 Light irradiation part 16 CCD camera 17 Control part 22 Drive motor 24 Strobe light source 25 Cover 26 Light diffusion plate

Claims (2)

[Claims] 1. A pattern reading device for reading a pattern recessed on a glossy surface to be measured, comprising: a light source; and a light diffusing plate disposed between the light source and the surface to be measured. And a light irradiating means for irradiating the measured surface with scattered light, and a reading means arranged at the specular reflection position with respect to the measured surface. Characteristic pattern reading device. 2. A pattern reading device for reading a pattern recessed on a glossy surface to be measured, comprising: a transporting unit for transporting an object to be measured having the surface to be measured; Detecting means for detecting the object to be conveyed; a strobe light source which is turned on instantaneously based on a detection signal of the detecting means; and an optical path between the strobe light source and the surface to be measured of the object to be measured. A light irradiating means for irradiating the surface to be measured with scattered light, comprising: a light diffusing plate provided; and a reading device provided at the specular reflection position with respect to the surface to be measured. Means for reading a pattern.