JPH0962831A - Image pickup device and illumination device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To input a clear video without illumination irregularity to a television camera by providing a hanging bell-shaped translucent diffusion plate in the circular light source of an illumination device. SOLUTION: A sensor generates a detection signal at a moment when a metallic can 1 passes right under the illumination device 2 and the television camera 4. The detection signal starts an illumination power through a picture processor, causes the illumination device 2 to emit light and irradiates the can bottom 11 of the metallic can 1. The video signal of the television camera is inputted to the picture processor in synchronizing with the detection signal. In the illumination device 2, the circular light source 22 is stored in a main body frame 21, the hanging bell-like transmission diffusion plate 23 is arranged at the lower side of the main body frame 21 with the opening part of a hanging bell facing the can bottom 11 of the metallic can 1, and a reflecting diffusion plate 24 is arranged at the upper side of the main body frame 21. The opening part of the hanging bell-shaped transmission diffusion plate 23 is shaped in a smooth arc from around the center of the circular light source 22 and a hanging bell-like upper end part is drawn/formed with the smooth arc.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an illuminating device and an image pickup device in an inspection device for inputting images such as characters and symbols written on an object to a photographing device such as a television camera and determining whether the object is acceptable or not.

[0002]

2. Description of the Related Art As a method of inspecting whether the serial number, the date of manufacture, etc. written on the bottom of metal cans for beverages etc. are correctly written, a character symbol on the bottom of a can is generally used with a TV camera. Is imaged and analyzed by an image processing device to determine whether it is good or bad.

As a precondition for the above-mentioned image processing, it is important to input a clear video into a television camera, and therefore various illumination devices have been proposed.

For example, in the illuminating device shown in FIG. 5, the light from the annular light source 22 is transmitted and diffused by the diffusion plate 26 to irradiate the can bottom 11. The diffusion plate 26 has a cylindrical portion 26a as shown in the figure.
And the flat plate portion 26b, and through the center hole of the cylindrical portion, the television camera 4 and the lens 4b image the character symbol on the can bottom 11 from above.

As an improvement plan to the method shown in FIG. 5, an illumination device shown in FIG. 7 has been proposed. Annular source 22
The light from is transmitted and diffused by the diffusion plate 27, and the can bottom 11 is illuminated. The diffusing plate 27 is composed of a conical portion 27a and a flat plate portion 27b as shown in the figure, and the character symbol on the can bottom 11 is picked up by the television camera 4 and the lens 4b from above through a central hole of the conical portion. In the improvement plan of FIG. 7, the shape of the diffuser plate is improved to a cone 27 of FIG. 7 with respect to the cylindrical portion 26a shown in FIG. 5, so that the diffusion term from the inner surface of the cone portion 27a can be reduced to 1
It is intended to reflect the light to 1 and irradiate it uniformly.

As an example of the above-mentioned prior art, Japanese Patent Laid-Open No. 5-17
No. 744, and a method of stacking conical diffusion plates in two stages is also disclosed in Japanese Patent Laid-Open No. 5-49971.

[0007]

In a testing device for photographing a character or symbol written on the bottom of a can such as a metal can for beverages with a TV camera and determining the quality of the character or symbol, a good image is input to the TV camera. In order to achieve this, it is a prerequisite that the bottom of the can is evenly lit, but there are various types of can bottom shapes such as convex, concave, and ring-shaped steps due to securing strength, etc. Hard to get.

Among the above-mentioned conventional techniques, the image by the illuminating device shown in FIG. 5 is as shown in FIG. 6, and the dark field 14 appears depending on the shape of the bottom of the can, and the difference in the contrast with the character image 13 is reduced, resulting in a false judgment. There is a problem that the character image 13 is buried in the dark field 14 and cannot be discriminated.

The cause of the dark field 14 is that the dark portion of the end surface of the lens 4b appears on the can bottom 11.
Is proposed, in which the upper part of the diffusion plate 27a is inserted inside the lens barrel of the lens 4b in order to reduce the reflection of the dark portion of the end surface of the lens 4b.

The image shown in FIG. 7 is as shown in FIG. 8, and the dark field 14 at the center is improved. However, depending on the shape of the bottom of the can, a dark ring 15 appears, and the image overlapped with the character image 13 is mistaken. There was a problem that it was impossible to distinguish or distinguish.

The cause of the dark ring 15 in FIG. 8 is that the transmission of the illumination light becomes poor at the joint portion 27c of the diffusion plate 27 in FIG. 7, and a ring-shaped shadow is reflected on the bottom of the can.

[0012] Metal cans for beverages, PET bottles, various vials for chemicals, etc. may be colored in various ways depending on the product image, and the construction with the character symbol written on the colored ground color is insufficient. In that case, there was a problem that it was difficult to determine.

The object of the present invention is to solve the above-mentioned problems, and to minimize the occurrence of partial dark field which could not be achieved by the above-mentioned prior art, and to use various cans such as metal cans. Gives uniform illuminance to the bottom shape, and
An object of the present invention is to provide an illumination device, an imaging device, an imaging method, and an automatic determination method that can obtain a clear image that is easily image-processed even with a character symbol written on a colored background color.

[0014]

In order to achieve the above object, according to the present invention, a bell-shaped semi-transparent diffusion plate is provided inside an annular light source of an illuminating device, and an upper part of the diffusion plate is formed into a smooth arc, and A central hole is provided in the center so that it does not obstruct the field of view of the TV camera, and the center cross-sectional shape of this diffuser plate is a bell-shaped skirt that has a moderate radius from the center of the annular light source and is smooth. Was formed into a flat plate shape that is in contact with, and has a structure facing the irradiation target side.

A reflection type diffusion plate is provided on the rear side of the annular light source, that is, in front of the lens of the television camera, and a small hole is provided in the center of the reflection type diffusion plate so as not to obstruct the visual field of the lens.

The lens of the television camera is a pinhole lens whose objective lens has a diameter as small as possible.

As another means, a flat plate-shaped semitransparent diffusion plate is provided on the side of the annular light source to be irradiated, and a hole as small as possible that does not obstruct the visual field of the pinhole lens is provided at the center of the flat plate-shaped semitransparent diffusion plate. To provide.

Further, various optical filters can be attached to the outside of the diffusion plate. A pinhole lens is arranged coaxially with the center of the ring of the annular light source, and an image of the object to be inspected is taken through the center hole of the plate-like semitransparent diffusion plate.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION An example of the present invention will be described with reference to FIGS. FIG. 1 shows an example of the overall configuration in the case where the present invention is applied to a character / symbol inspecting device, for example, which is marked on the bottom of a metal can. The can of a metal can 1 conveyed on a conveyor 3 is shown. To inspect the letters and symbols marked on the bottom 11,
The illuminating device 2 is disposed above, and the pinhole lens 4a is attached to the television camera 4 so that the can bottom 11 of the metal can can be imaged from above through the center hole 24a of the illuminating device 2.

The sensor 5 generates a detection signal at the moment when the metal can 1 passes directly under the lighting device 2 and the television camera 4, and the detection signal is transmitted via the image processing device 6 to the lighting power source 2.
A is started, the lighting device 2 is caused to emit light, and the can bottom 11 of the metal can is illuminated. At the same time, the video signal of the television camera 4 is input to the image processing device 6 in synchronization with the detection signal. The image processing device 6 performs a predetermined analysis process on the video signal to determine whether it is good or bad, and rejects defective products by the sorting mechanism 7.

FIG. 2 shows a central cross section of the illuminating device in the entire structure shown in FIG.
The television camera 4 and the pinhole lens 4a are in a positional relationship as shown in the figure. The dotted arrow indicates an example of the optical path.

The structure of the illuminating device is such that an annular light source 22 is housed in a main body frame 21, a bell-shaped transmission type diffusion plate 23 is provided below the main body frame 21, and an opening portion of the bell is provided in a can bottom 11 of a metal can. The reflection type diffusion plate 24 is disposed on the upper side of the main body frame 21.
Place. The inner side surface 21A of the body frame 21 may be white so as to be easily reflected, but it may be a simple metallic color because it does not significantly affect the overall light diffusion.

The opening of the bell-shaped transmission type diffuser plate 23 is formed so as to have a smooth circular arc from the vicinity of the center of the annular light source 22, and the upper end of the bell-shaped transmission is also narrowed by the smooth circular arc.

As for the shape of the bell-shaped transmission type diffusion plate 23, it is desirable that the bell-shaped upper part and the joint portion of the flat plate and the cylinder are integrally molded so that no shadow is produced. The material may be translucent plastic, frosted glass, translucent paper or cloth, as long as it uniformly permeates and diffuses. Normally, a milky white material is used, but if the letters and symbols are written on a colored background such as metal cans and bottles, the color of the diffuser plate is a colored translucent material, and the background color and the letters and symbols due to the filter effect. It is possible to increase the contrast and capture clear images.

The reflective diffuser plate 24 is arranged above the annular light source, and its position can be adjusted by changing the thickness of the distant piece 25, for example.

Further, the central hole 24a of the reflection type diffusion plate 24 is formed.
Is set as small as possible within a range that does not hinder the visual field of the pinhole lens 4a.

The reflection surface of the reflection type diffusion plate 24 may be a matte reflection surface coated with a material having a high reflection efficiency such as aluminum powder, glass powder, ceramic powder or the like so that scattered light can be obtained.

FIG. 3 shows a typical example of a character image on the bottom of a can captured by the lighting device of FIG. As compared with FIGS. 6 and 8 shown in the prior art, a uniform can bottom image is obtained, and the character image 13 is captured with a clear contrast. The image of the stepped portion 12 on the bottom of the can in FIG. 2 corresponds to 12a in FIG. 3, but in the conventional lighting device, the shadow of the stepped portion appears as a clear dark ring, and in the portion overlapped with the character image 13, However, according to this example, the ring portion 12a due to the shadow of the step on the bottom of the can hardly appears, and even a subject whose character end is on the step can be easily identified. can do.

FIG. 4 shows an embodiment applied to the character inspection of a bottle, for example, a character symbol 1 written on the surface of the bottle 10.
6 or the character code 1 written on the bottle cap
7 is determined. The dotted arrow indicates an example of the optical path.

The illuminating device 2 is arranged so as to face the surface to be illuminated of the bottle, and the pinhole lens 4a and the television camera 4 are arranged coaxially. The illumination device 2 is provided with an annular light source 22, and a flat translucent diffuser plate 28 is provided on the irradiation target side.
In the central portion of the plate-like semi-transparent diffusion plate, a hole as small as possible that does not obstruct the visual field of the pinhole lens 4a is provided. Device 2
The inner side surfaces 2A, 2B may be white or black, but it is preferable that the side surface 2B is also white and serves as a diffusion plate.

Further, a guide portion 29 is provided on the outer side of the diffusion plate so that various colored filters 29 can be mounted.
With the background color of the bottle and the color of the printed letters and symbols, it is possible to easily exchange the pass filters of various colors and brightness so that the contrast can be obtained most clearly.

Although the above embodiments have described the lighting device and the image pickup device for character and symbol inspection of metal cans and bottles, they are not limited to metal cans and bottles, and they have a carton or gloss, or have a printed surface colored. Alternatively, the present invention can be applied to an object such that the irradiation surface has a complicated shape such as unevenness and uniform illumination cannot be obtained by an ordinary illumination means, or an object having a low contrast and a clear image cannot be obtained. The example of the filter can be applied to FIG.

According to the present embodiment, the bell-shaped transmission type diffusion plate has a cross-sectional shape with an appropriate radius from the vicinity of the center of the annular light source, and the upper end of the diffusion plate is rounded with a smooth arc, so that the diffusion plate is The brightness becomes uniform, and the irradiation target side is uniformly irradiated. In addition, the reflection type diffusion plate installed on the rear side of the annular light source supplements the illuminance near the central portion and suppresses the occurrence of a dark field.

Further, by combining with a pinhole lens having a small diameter of the objective lens, the reflection of the lens is eliminated and the occurrence of dark field is suppressed.

Furthermore, by making the filter removable, it is possible to obtain a video image with clear contrast and which is easy to process.

[0036]

According to the present invention, the light from the annular light source of the illuminating device is uniformly scattered by the bell-shaped transmissive diffuser plate, the reflective diffuser plate, and the pinhole lens to obtain a metal can bottom or the like. By irradiating the object to be illuminated with, it is possible to input a clear image with no illumination unevenness to the television camera.

For example, the illumination device and the image pickup device are
By applying it to the character / symbol inspection device for metal cans and bottles, even if the bottom of the can has various shapes such as concave and convex, the image of the character and symbol can be clearly extracted and the quality can be reliably judged. can do.

Further, even if the printed surface and the character symbols are colored, an image with clear contrast can be obtained.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a metal can character symbol inspection device.

FIG. 2 is a central cross-sectional view of an annular lighting device.

FIG. 3 is an image view of a bottom of a metal can illuminated by an annular illumination device.

FIG. 4 is a diagram showing another embodiment of the ring illumination device.

FIG. 5 is an example view of a lighting device according to the prior art.

FIG. 6 is an image view of a bottom of a metal can according to the related art.

FIG. 7 is a diagram illustrating an example of a lighting device according to the related art.

FIG. 8 is an image view of a bottom of a metal can according to the related art.

[Explanation of symbols]

 1 Metal Can 2 Annular Lighting Device 2a Illumination Power Supply 3 Conveyor 4 Television Camera 4a Pinhole Lens 5 Sensor 6 Image Processing Device 7 Sorting Mechanism 10 Bottle 11 Can Bottom 12 Can Bottom Step 13 Character Image 14 Can Bottom Dark Field 15 Can Dark field at the bottom 16 Character symbol of bottle 17 Character symbol of bottle cap 21 Illumination body frame 22 Annular light source 23 Bell-shaped transmissive diffuser plate 24 Reflective diffuser plate 25 Distant piece 26 Transmissive diffuser plate 27 Transmissive diffuser plate 28 Transparent Diffuser 29 Filter

Claims (10)

[Claims] 1. An annular light source, an image pickup means including a television camera and a lens for picking up light from an opening at an end of the lens, and an image pickup means provided along the opening of the annular light source and having one of upper and lower surfaces thereof. The image pickup means is provided on the other side, and the transmission type light diffuser plate is provided with the subject to be imaged on the other surface side, and the transmission type light diffuser plate is provided at the end opening on the image pickup means side. An imaging device that has a bell-shaped opening that has an opening of a corresponding size and that becomes larger on the subject side as it approaches the subject. 2. An annular light source, a means for imaging light from a lens end opening, which comprises a television camera and a lens, and a reflection type diffusion plate having an opening into which the lens end opening is inserted, opposed to or in contact with. , A transmission type light diffuser that is provided along the opening of the annular light source, has the reflective diffuser plate on one surface side of the upper and lower surfaces thereof, and has an object to be imaged on the other surface side. In addition to the plate, this transmission type light diffusion plate has a bell shape with an opening of a size corresponding to the opening on the reflection type diffusion plate side, and an opening that becomes larger on the subject side as it approaches the subject. An imaging device that was made into an eggplant. 3. The image pickup device according to claim 1, wherein the lens is a pinhole lens, and the subject is a metal can or a bottle. 4. An image pickup means comprising an annular light source, a television camera and a pinhole lens, wherein the pinhole lens is arranged so as to penetrate through the opening of the annular light source, and the tip of the pinhole lens is in contact with or inserted into the tip. An image pickup apparatus comprising: a light-transmitting diffuser plate that has an opening that opposes the tip lens opening; and a removable optical filter that is provided between the light-transmitting diffuser plate and the subject side. 5. The image pickup device according to claim 1, wherein the light transmission type diffusion plate is made of any one of semitransparent plastic, frosted glass, and semitransparent paper (or cloth). 6. The image pickup device according to claim 2, wherein the light reflection type diffusion plate is made of any one of aluminum powder, glass powder, and ceramic powder capable of obtaining scattered light. 7. A reflection type diffusion plate having a small opening, a distant piece supporting the reflection type diffusion plate, and an illumination means provided on the other side of the distant piece, and the illumination means comprises: An annular light source, and along the opening of the annular light source, and along the up and down direction thereof, have a first opening of a size corresponding to the small opening of the reflective diffuser plate on the upper side, and an end on the lower side. An illumination device including a bell-shaped transmission diffuser plate having a second opening that becomes larger toward the center. 8. A metal can, wherein the image pickup device according to claim 1 or 2 picks up an image of a character on the bottom of a metal can as an object, analyzes the image of the imaged character, and determines the quality of the character. Automatic determination method for bottom letters. 9. The color character or color pattern on the side of a metal can or a bottle as an object is imaged by the imaging device according to claim 4, and the image analysis of the imaged color character or color pattern is performed, and the color character Alternatively, an automatic determination method of characters on a metal can or bottle that determines the quality of a color pattern. 10. A metal can or bottle conveyed on a belt conveyor is used as a subject, and the imaging device according to claim 1 or 4 is installed toward the subject, and the metal can or bottle reaches the installation position. This is detected by a sensor, and in synchronism with this detection, an annular light source of the image pickup device is turned on to perform image pickup, and an image of a character or character pattern of a metal can or a bin on a belt conveyor is picked up.