JP3339426B2 - Quality inspection equipment - 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 of irradiating an object such as a sheet or a continuous sheet having a hologram layer with light, and judging the quality of the object based on the light intensity distribution of the reflected image. To a quality inspection device.

[0002]

2. Description of the Related Art In recent years, holograms have been attracting attention as being capable of displaying a stereoscopic image or a pattern and thus having a high source display function because they are difficult to forge and are expected to have a high fraud prevention effect. It is used by attaching to securities, publications and wrapping paper. Accordingly, the need for an apparatus for inspecting the quality of an inspection object including such a hologram has increased.

As a conventional quality inspection apparatus, an apparatus having a schematic configuration shown in FIG. 4 is generally used. The quality inspection device 30 includes a light source 33 for irradiating an inspection object 32 such as a sheet or a continuous sheet conveyed in the arrow direction 31 at a predetermined inclination angle θ1 and a reflection light for reflecting light at an inclination angle θ2. An imaging camera 34 for receiving light and capturing a reflected image thereof; and a determination unit 35 for determining the quality of the inspection object 32 based on the light intensity distribution of the reflected image.
It is composed of The position of the light source 33 is
With respect to the specular reflection component of the inspection surface of the inspection object 32 (the angle θ
1 and an angle θ2 are equal or a scattered light component of the inspection surface (a reflected light component where the angle θ1 and the angle θ2 are different) is different. It is adjusted to obtain a light component. For example, a dark-field image based on a scattered light component is suitable for inspection of a printed surface or an aluminum laminated surface using color ink, and a bright-field image based on a specularly reflected light component is suitable for a transparent / translucent film or coated paper. Is suitable.

[0004]

However, the conventional quality inspection apparatus as described above inspects the shape of a hologram, a pinhole, and the like, and accurately inspects the recording state of a hologram reproduced image on a hologram layer. Was not. Conventionally, the recording state has been visually inspected.

There is another problem even if the hologram reproduction image can be inspected without visual inspection. That is, the object to be inspected includes a hologram layer, a printing surface, an underlayer, and the like. In order to keep inspection costs low and increase inspection efficiency, the hologram layer, the printing surface, It is desired to inspect the surface and the substrate at the same time. However, the hologram shows a completely different hologram reconstructed image when the light irradiation angle is changed, and it is necessary to select the most suitable hologram reconstructed image from these reconstructed images for inspection. Therefore, if the incident angle of the irradiation light is adjusted so as to obtain a desired hologram reconstructed image, only an image unsuitable for the inspection of the printing surface or the base is obtained, and conversely, the light irradiation angle suitable for the inspection of the printing surface or the base is obtained. Gives a problem that only a hologram reconstructed image unsuitable for inspection can be obtained.

[0006] The hologram is often inspected while being attached to a base such as a sheet of paper. At the time of this inspection, there was a problem that the hologram reproduced image was greatly changed due to slight fluttering of a sheet or the like, and a stable and highly accurate inspection could not be performed.

SUMMARY OF THE INVENTION In view of the above problems, the present invention makes it possible to inspect a hologram portion of an inspection object without visual inspection, and uses a single device to combine the hologram portion of the inspection object with a portion other than the hologram. It is an object of the present invention to provide a quality inspection device capable of simultaneously inspecting a high-quality product.

[0008]

In order to achieve the above object,
A quality inspection apparatus according to a first aspect of the present invention includes:
An imaging unit that receives reflected light from the inspection region and captures an image of the inspection region; anda determination unit that determines the quality of the inspection object based on a light intensity distribution of an image of the inspection region. The hologram layer is irradiated with light at a predetermined incident angle, and one or a plurality of hologram inspection light sources for providing a hologram reproduction image recorded on the hologram layer to the imaging means. quality quality of the hologram layer distributed into groups is determined
An inspection apparatus, wherein the inspection area is configured to carry the inspection object.
A line-shaped area over the feed width, and the transfer speed of the inspection object
Degree, and every time the inspection object is transported a predetermined distance,
Pulse generating means for outputting a pulse signal;
And the object to be inspected has a line width of the linear region.
Each time it is transported, the imaging camera as the imaging means is commanded to take an image.
Control signal to output a command signal
Two-dimensional image synthesizing means for synthesizing an area image into a two-dimensional image
It is to characterized in that it comprises a.

A quality inspection apparatus according to a second aspect of the present invention includes a light source or a plurality of light sources for irradiating an inspection area of an inspection object including a hologram layer with light, and a light receiving means for receiving reflected light from the inspection area. Imaging means for imaging, and determining means for determining the quality of the inspection object based on the light intensity distribution of the image of the inspection area, wherein the light source irradiates the hologram layer with light at a predetermined incident angle; One or more hologram inspection light sources for providing a hologram reconstructed image recorded on the hologram layer to the imaging means, and irradiating a printing surface or a base constituting the object to be inspected with light at an incident angle different from the incident angle, and performing the printing. It is characterized by comprising one or more ordinary light sources for providing a reflection image of the surface or the base to the imaging means, and the quality of the hologram layer and the printing surface or the base is simultaneously determined by the determination means. That.

The quality inspection apparatus according to the first and second aspects of the present invention transmits and scatters the light emitted from the hologram inspection light source from the viewpoint of preventing a change in the reproduced hologram image due to the flapping of the inspection object. It is desirable to provide a light diffusing member that irradiates the inspection area with substantially uniform scattered light.

The determining means compares the density level of the multi-tone image data obtained from the light intensity distribution of the reflected image picked up by the image pick-up means with the reference density level of the master image data. It is preferable to use means for judging the quality of the paper.

Further, in order to clearly obtain the hologram reproduced image, particularly the boundary portion of the reproduced image, the reflected light of the inspection area may be received by the image pickup means through a filter which transmits only light in a specific wavelength range. it can.

Further , in the quality inspection apparatus according to the second aspect of the present invention, a line-shaped area extending over a conveyance width of the inspection object can be set as the inspection area. This is realized by using a line sensor or the like. A pulse generating means for detecting a transfer speed of the inspection object and outputting a pulse signal every time the inspection object is conveyed by a predetermined distance; and, based on the pulse signal, the inspection object A control circuit that outputs an imaging command signal to the imaging camera each time the line width of the linear region is conveyed, and a two-dimensional image combining unit that combines a sequentially captured image of the linear region into a two-dimensional image. A two-dimensional image of the surface of the inspection object can be obtained.

The inspection area may be set as a two-dimensional area other than a linear area, and the two-dimensional area may be imaged using an area sensor.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, various representative embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram showing a first embodiment of a quality inspection apparatus according to the present invention. The quality inspection apparatus 1 according to the present embodiment includes a sheet 4 as an object to be inspected, which is disposed on a conveyor belt 2 and is conveyed in an arrow direction 3, and a hologram inspection for irradiating an inspection area of the object 4 with light. A light source 5 and a normal light source 6, an imaging camera 7 such as a line sensor that receives reflected light from the inspection area and captures an image thereof, and image data of the inspection area from the imaging camera 7 are transferred. Judging means 8 for judging the quality of the state of the inspection object based on the light intensity distribution
And a rotary encoder 9 for detecting the rotation speed of the roller 2 a rotating in contact with the conveyor belt 2, and an imaging command signal based on an output signal of the rotary encoder 9.
And a control circuit 10 for outputting to the control circuit. Although the inspection object in this embodiment is a sheet, the invention is not limited to this, and the inspection object may be a continuous sheet.

The inspection object 4 is, for example, a single sheet printed material divided into a plurality of sections as shown in FIG. 2. In each section, a hologram layer
Printed surfaces 13a, 13b denoted by "A", "B", "C"
, 13c,... Are formed. These hologram layers are composed of a rainbow hologram, a Lippmann hologram and the like. Further, the imaging camera 7 captures an image of the linear inspection area 15 indicated by a chain line in the figure including the hologram layer, the printing surface, and the base, and the image data is transferred to the determination means 8. Light source for hologram inspection 5
Is a predetermined inclination angle θ to such hologram layers 12,.
In step 1, the inspection light is made incident, and the hologram layers 12,... Are arranged so as to give a single hologram reproduction image suitable for inspection to the imaging camera 7. Here, in order to clearly obtain a hologram reproduction image, or to obtain the hologram layer 12,.
It is preferable that a means for finely adjusting the inclination angle of the hologram inspection light source 5 be provided in order to select another hologram reproduction image recorded in the hologram inspection object as the inspection target. In addition, the normal light source 6 irradiates the printing surface and the base except for the hologram layer with light at an inclination angle θ2 so as to provide the imaging camera 7 with a bright field image or a dark field image most suitable for inspection of the printing surface or the base. Placed in However, the position of the normal light source 6 is
The adjustment is appropriately made within a range that does not affect the hologram reproduction image captured by the imaging camera.

Here, a filter (not shown) that transmits only light in a specific wavelength range may be provided in the imaging camera, and only light components in a specific range of the reflected light of the inspection object may be provided to the imaging camera. . Thereby, the boundary portion of the hologram reproduction image becomes clear, and the inspection accuracy can be improved. This is because, since the hologram is a kind of diffraction grating, the boundary between the three-dimensional image and the pattern, which is the hologram reproduction image, is easily separated into light beams having different wavelengths, and is likely to be unclear.

The timing for picking up the line image data is determined by the control means 10. That is, in the rotary encoder 9 of FIG.
It contacts and rotates with the roller 2a, which rotates in proportion to the transport speed of the transport belt, and detects the amount of rotation of the rotating drum 9a using a magnetic sensor or an optical sensor, and the amount of rotation is sent to the control means 10 as a pulse signal. Is output. The roller 2a
Are interposed for the purpose of preventing the disturbance of the pulse due to the joint of the conveyor belt and the like. The control means 10 outputs an imaging command signal to the imaging camera every time the inspection object is conveyed a predetermined distance based on the input pulse signal, and the imaging camera receiving the signal outputs the line-shaped signal. The inspection area is sequentially imaged. Here, by adjusting the timing of outputting the imaging command signal in advance, the surface of the inspection object can be sequentially imaged without breaks. In addition, the sequentially captured image data is sequentially stored in the memory. Then, the image data of the linear area stored in the memory is seamlessly combined and output as a two-dimensional image to an image display means such as a CRT.
As a result, the surface condition of the inspection object flowing through the inspection line can be reduced to 2
It is possible to obtain a two-dimensional image in real time.

In the judgment means 8, the master image data of the inspection object having no abnormality is taken in advance and stored in the memory after multi-tone image processing (for example, image processing of 256 tones). The image data of the inspection area imaged as described above is subjected to image processing as multi-gradation data by the judgment means 8, and the density level of this image data is compared with the reference density level of the master image data in pixel units.
If the comparison results in a difference in density level equal to or larger than the allowable amount, the judging means 8 identifies the pixel portion of the image data as a defective portion. The certification result may be transferred to a speaker and output as a warning sound or the like, or may be transferred to the above-described image display means such as a CRT and visually checked. When a color image is subjected to multi-tone image processing, multi-tone image processing can also be performed on color components constituting the color image, for example, primary color signals of three primary colors of red, green, and blue.

The object to be inspected according to the present invention may be composed of a light transmitting material in addition to the light reflecting material. The quality inspection apparatus according to the present invention irradiates these inspection objects with the light of the ordinary light source as described above, and their properties (scratch, chipping, defective material,
Dents, wrinkles, breaks, etc.). Examples of the printing surface on the inspection object include gravure printing, offset printing, flexographic printing, and screen printing.
In addition, examples of the inspection surface suitable for the inspection based on the dark field image include a surface printed with color ink and an aluminum laminate surface. In particular, in the case of a printing surface made of color ink, the light intensity is too strong from the image of the specular reflection light component to make it difficult to identify the color component. Therefore, it is desirable to obtain a dark-field image mainly containing a scattered light component. On the other hand, inspection surfaces and inspection objects suitable for inspection based on bright-field images include transparent and translucent films and coated papers, vacuum-deposited aluminum and silver on a substrate, or metal on the surface by sputtering. And a thin film formed by evaporating particles.

The hologram formed on the inspection object is preferably a Lippmann hologram or a rainbow hologram capable of obtaining a reproduced image even when irradiated with white light. As a Lippmann hologram, for example, a volume phase type hologram, that is, a hologram recording material is applied on a base material, and two phase-modulated wavefronts are irradiated on the hologram recording material layer to obtain a three-dimensional image or pattern information. Is recorded, and then, if necessary, a protective film is coated on the hologram recording material layer. As the rainbow hologram, for example, an embossed hologram, that is, a resin layer made of a thermoplastic resin or the like is formed on a base material, and then, using a stamper having a relief hologram, by a flat pressure press method or a roll press method. An example in which a fine concavo-convex pattern of the relief hologram is transferred to the resin layer, and a metal reflection layer or the like is formed on the transferred image. These Lippmann holograms and rainbow holograms may be adhered to the inspection object using an adhesive or the like, or may be formed directly on the inspection object.

Examples of the hologram inspection light source include a fluorescent lamp, a laser that emits monochromatic light, and a sodium lamp. A fluorescent lamp is preferable in consideration of low cost and ease of handling. Examples of the ordinary light source include a fluorescent lamp, a halogen lamp, and a metal halide lamp capable of stably emitting light even under a high-temperature environment. In addition, it is preferable that the quality inspection apparatus includes a dimming unit that adjusts a light amount ratio between the hologram inspection light source and the normal light source according to the state of the inspection area, so that a clear image can be obtained more selectively. For example, when the hologram reproduction image is emphasized more than the image of the printing surface or the base, and it is desired to clearly detect the property abnormality of the hologram layer (partial loss of the layer, mixing of foreign matter, etc.), the light amount of the hologram inspection light source is required. What is necessary is just to set it larger than the light quantity of a normal light source.

Further, as an imaging camera according to the present invention,
It is preferable to use a line sensor in order to capture an image of a linear region over the transport width of the inspection object. As this line sensor, one in which solid-state imaging devices such as a CCD (Charge Coupled Device) and a photodiode are arranged, for example, 2
56 pixels, 512 pixels, 1024 pixels, 2048 pixels,
A high-precision line sensor having 4096 pixels and 8192 pixels can be used. However, if the entire width of the line-shaped inspection area cannot be covered by one line sensor, a plurality of line sensors are arranged along the inspection area, and each image data obtained by these line sensors is synthesized. An image of the entire inspection area can be obtained. Note that such a line sensor is not limited to one for black-and-white imaging, but may be one for color imaging.

Next, as shown in FIG. 3, in a quality inspection apparatus 20 having substantially the same configuration as the apparatus shown in FIG. 1, the light emitted from the hologram inspection light source 24 is transmitted and scattered, and When the light diffusing member 28 for irradiating the light 29 is provided, it is possible to prevent the inspection object such as a sheet-fed printed material from fluttering, thereby largely changing the hologram reproduction image and making the inspection impossible. As the light diffusing member 28, a milky white translucent member can be adopted. When a linear light source capable of uniformly irradiating light over the entire width of the linear inspection area is used as the hologram inspection light source, the shape of the light diffusion member 28 is changed to a linear light source. It is preferable to form a roof having a semi-cylindrical roof over the entire length in the longitudinal direction.

In all of the preferred embodiments described above, the inspection area is a linear area. However, the present invention is not limited to this. The inspection area is set as a two-dimensional area, and the two-dimensional area is defined as an area. It also includes an image taken by using a sensor or the like. Examples of the area sensor include a two-dimensional array of solid-state imaging devices such as a CCD.

[0026]

As described above, the quality inspection apparatus of the present invention
A hologram layer is irradiated with light at a predetermined incident angle, and one or a plurality of hologram inspection light sources for providing a hologram reproduction image recorded on the hologram layer to the imaging means are provided, and the light intensity of the hologram reproduction image captured by the imaging means is provided. Since the quality of the hologram layer is determined by the determination means based on the distribution, a highly accurate hologram inspection can be performed without visual observation.

Further, the quality inspection apparatus of the present invention irradiates the hologram inspection light source and a printing surface or a substrate constituting an inspection object with light at an incident angle different from the incident angle, and Since one or more ordinary light sources that provide a reflected image to the imaging unit are provided, and the determination unit determines simultaneously whether the hologram layer included in the inspection area and the printing surface or the base are good or bad, a single device is used. hand,
It is possible to clearly obtain an image including both the hologram portion of the inspection object and the other printed surface or base, and to clearly determine the quality of the inspection object.

Further, when such a quality inspection apparatus includes a light diffusing member that transmits and scatters the light emitted from the hologram inspection light source and irradiates the inspection area with substantially uniform scattered light, It is possible to prevent the hologram reproduction image from being disturbed due to flapping or the like.

Further, by allowing the image pickup means to receive the reflected light of the inspection light source through a filter that transmits only light in a specific wavelength range, the inspection accuracy of the boundary portion of the hologram reproduced image can be improved.

A pulse generating means for detecting a transfer speed of the inspection object and outputting a pulse signal every time the inspection object is transported by a predetermined distance; and detecting the inspection object based on the pulse signal. A control circuit for outputting an imaging command signal to an imaging camera every time the line width of the linear area is conveyed, and combining a sequentially captured image of the linear area into a two-dimensional image;
The provision of the two-dimensional image synthesizing means makes it possible to obtain the surface state of the object to be inspected in real time as a two-dimensional image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing one embodiment of a quality inspection apparatus according to the present invention.

FIG. 2 is a schematic diagram showing an example of an inspection object according to the present invention.

FIG. 3 is a schematic configuration diagram showing an embodiment of another quality inspection device according to the present invention.

FIG. 4 is a schematic configuration diagram of a conventional quality inspection device.

[Explanation of symbols]

1 Quality inspection device 2 Conveyor belt 2a Roller (rotating body) 3 Transport direction 4 Object to be inspected (sheets) 5 Light source for hologram inspection 6 Normal light source 7 Imaging camera 8 Judging means 9 Rotary encoder 9a Rotating drum 10 Control circuit 11 Substrate 12 Hologram layers 13a, 13b, 13c Printing surface 14 Transport direction 15 Inspection area 20 Quality inspection device 21 Transport belt 21a Roller (rotating body) 22 Transport direction 23 Inspection object 24 Hologram inspection light source 25 Normal light source 26 Imaging camera 27 Rotary encoder 28 Light diffusion member 29 Scattered light 30 Quality inspection device 31 Transport direction 32 Inspection object 33 Light source 34 Imaging camera 35 Judgment means

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-1-96685 (JP, A) JP-A-6-160301 (JP, A) JP-A-2-248845 (JP, A) JP-A-5-205 18728 (JP, A) JP-A-9-152322 (JP, A) JP-A-8-15178 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/89-21 / 892 B41F 33/14

Claims (8)

(57) [Claims] A light source for irradiating an inspection area of an inspection object including a hologram layer with light; an imaging unit for receiving reflected light from the inspection area and imaging the inspection area;
Determining means for determining the quality of the object to be inspected based on the light intensity distribution of the image of the inspection area, wherein the light source irradiates the hologram layer with light at a predetermined incident angle and is recorded on the hologram layer. A quality inspection comprising one or more hologram inspection light sources for providing a hologram reproduction image to an imaging means, wherein the quality of the hologram layer is determined by the determination means based on the light intensity distribution of the hologram reproduction image
An apparatus, wherein the inspection area has a line shape extending over a conveyance width of the inspection object.
A detection area for detecting the transfer speed of the inspection object and moving the inspection object over a predetermined distance.
A pulse generator that outputs a pulse signal every time a separation is carried
And a step, based on the pulse signal, wherein the object to be inspected is in the form of a line.
Each time the line width of the area is transported,
A control circuit for outputting an imaging command signal to the image camera;
Second order to combine the image of the imaged linear area into a two-dimensional image
A quality inspection device comprising an original image synthesizing means . A light source for irradiating an inspection area of the inspection object including the hologram layer with light, an imaging unit for receiving reflected light from the inspection area and imaging the inspection area;
Determining means for determining the quality of the object to be inspected based on the light intensity distribution of the image of the inspection area, wherein the light source irradiates the hologram layer with light at a predetermined incident angle and is recorded on the hologram layer. One or more hologram inspection light sources for providing a hologram reconstructed image to the image pickup means; and a printed surface or a base constituting the object to be inspected is irradiated with light at an incident angle different from the incident angle, and a reflected image of the printed surface or the base is provided. A quality inspection apparatus comprising: one or a plurality of normal light sources for supplying the image data to an imaging unit; and determining whether the hologram layer and the printing surface or the base are good or bad at the same time by the determination unit. 3. The inspection area covers an inspection object transport width.
3. The quality inspection device according to claim 2, wherein the quality inspection device is a linear region. 4. A method for detecting a transfer speed of an object to be inspected,
Outputs a pulse signal each time the
The inspection object is based on the line signal based on the pulse signal.
Each time the line width of the area is transported, the imaging command is issued to the imaging camera.
A control circuit for outputting a signal, and combining a sequentially captured image of the linear region with a two-dimensional image.
4. The quality inspection according to claim 3, further comprising a two-dimensional image synthesizing means.
Inspection equipment. 5. The method according to claim 1, wherein the inspection area is set as a two-dimensional area.
3. The imaging device according to claim 2, wherein the two-dimensional area is imaged using an area sensor.
Quality inspection equipment. 6. A hologram inspection light source for transmitting outgoing light.
Scattered light to illuminate the inspection area with substantially uniform scattered light.
The light diffusing member for emitting light according to any one of claims 1 to 5,
Quality inspection device as described. 7. The image processing device according to claim 7 , wherein
Multi-tone image obtained from the light intensity distribution of the captured reflected image
The density level of the data is set to the reference density level of the master image data.
To determine the quality of the inspection area by comparing
The quality inspection device according to claim 1. 8. The method according to claim 1, wherein the reflected light in the inspection area is reflected in a specific wavelength range.
The imaging means through a filter that transmits only light of
The quality inspection according to any one of claims 1 to 7,
Inspection equipment.