JP3259070B2 - Lenticular lens sheet defect inspection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for inspecting the appearance of a lenticular lens sheet used in a transmission type projection screen, and more particularly to a compact automatic inspection apparatus capable of detecting in-line black defects of a lenticular lens sheet. About.

[0002]

2. Description of the Related Art A lenticular lens sheet for a transmission type projection screen or the like is made of a transparent resin such as acrylic, and is manufactured by extrusion molding. Local changes, that is, foreign matters and bubbles inside the resin, stains and scratches on the resin outer surface, and the like occur. Most of these local changes in appearance, when a lenticular lens sheet is used as a screen, locally change the light transmittance (light transmission amount) and impair uniformity. Was needed. Most of these appearance defects locally reduce the light transmittance (light transmission amount).
This is called a black defect, and this black defect inspection is generally called an appearance defect inspection. Conventionally, as a method of inspecting the appearance defect of a lenticular lens for a transmission type projection screen or the like, there is no suitable automatic inspection apparatus, and a method of visual inspection by a human has been adopted. However, in recent years, lenticular lenses have been increasingly required to be of high quality and mass production. Conventional inspection with the naked eye is not performed manually because of differences between humans and problems in reproducibility. Inspection by automated equipment has been required. In addition, inspections using automated equipment have been required for mass production.

[0003]

Under such circumstances, in response to the mass production of lenticular lenses for transmission type projection screens, etc., the defect detection of the lenticular lens is once performed by a compact automatic appearance inspection apparatus. Was required to do so. The present invention relates to an automatic visual inspection device for a lenticular lens, and in detail,
The present invention relates to a compact automatic visual inspection device capable of detecting a black defect of a lenticular lens inline.

[0004]

A lenticular lens sheet defect inspection apparatus according to the present invention uses a transmission illumination while moving a lenticular lens sheet at a constant speed in the lens direction of a lenticular lens, and linearly moves the lenticular lens sheet from the light exit surface side. An automatic inspection device that detects a black defect by capturing an image by an area imaging unit and performing image processing on a signal obtained by the imaging, the device including: a front surface of the lenticular lens sheet, a direction perpendicular to a moving direction of the lenticular lens sheet. A first linear region imaging unit that captures an image including a predetermined width on a straight line on the lens surface across the width, and that captures a predetermined region of the sample by moving the lenticular lens sheet; and the first linear region. First image forming means for forming an image of a lenticular lens sheet on an image receiving surface of an image pickup means, and a lenticular lens The lenticular lens sheet moves at an angle including a predetermined width on a straight line on the sheet surface across the width in the direction orthogonal to the moving direction of the lenticular lens sheet, obliquely from one side surface parallel to the moving direction of the sheet. A second linear area imaging means for imaging a predetermined area of the sample by doing, a second imaging means for imaging the image of the lenticular lens sheet on the image receiving surface of the second linear area imaging means, Obtain an image including a predetermined width on a straight line on the sheet surface, crossing the width in the direction perpendicular to the moving direction of the lenticular lens sheet, obliquely from the other side surface parallel to the moving direction of the lenticular lens sheet, and imaging the lenticular lens sheet. A third linear area imaging means for imaging a predetermined area of the sample by moving the lenticular lens on the image receiving surface of the third linear area imaging means; Third image forming means for forming an image of a sheet, illuminating means for transmitting bright-field illumination to each linear area image capturing means, and image processing means for performing image processing of an image signal captured by each image capturing means. The first linear region imaging unit is provided with an imaging unit, and the imaging by the second linear region imaging unit and the third linear region imaging unit is performed by tilting imaging so that normal imaging can be performed. In order to make it possible, the linear area imaging means and the imaging means are arranged in association with each other.
Each of the linear region imaging means includes one or a plurality of linear region imaging units, and each of the imaging units corresponds to one of the linear region imaging units of each of the corresponding linear region imaging units. The linear region imaging means adjusts the width in the direction perpendicular to the moving direction of the lenticular lens sheet by adjusting the field of view of the one or more linear region imaging units. An image is taken over a straight line on the sheet surface including a predetermined width. In particular, the above-mentioned lenticular lens is effective when it is a lenticular lens sheet for a transmission type projection screen having a lenticular lens array on the light exit surface side as shown in FIG. This lenticular lens sheet is shown in FIG.
Having an arrangement of convex portions (lens portions) in the shape of a semicircle as shown in
In the case of FIG. 6, a lenticular lens array is provided on both the image pickup side (light emitting surface side) and the light source side (illumination side). Here, the lens direction refers to the direction in which the convex portions in the shape of a semicircle are connected. In this case, the tilt shooting is to form an image of a sample on an image receiving surface of an imaging unit by using a peripheral portion of an angle of view of an imaging unit (lens system) as shown in FIG. The normal imaging refers to imaging that is not tilting imaging. Also, "oblique from the side surface parallel to the moving direction of the lenticular lens" means from a position closer to the side surface parallel to the moving direction than directly above the lens convex portion.

An automatic inspection apparatus according to the present invention is an apparatus for inspecting a defect while moving a lenticular lens sheet at a constant speed in a lens direction.
The lenticular lens sheet is imaged on a straight line perpendicular to the moving direction including the entire area of a predetermined width, and the lenticular lens sheet is moved to image a predetermined area of the lenticular lens sheet. Each of the linear region imaging means includes one or a plurality of linear region imaging units, and each imaging unit has one imaging unit corresponding to each linear region imaging unit of the corresponding linear region imaging unit. Corresponding to one
Each of the linear area imaging means includes one or a plurality of imaging units (lens systems), and each linear area imaging unit adjusts the field of view of one or a plurality of linear area imaging units so that the linear area imaging means is orthogonal to the moving direction of the lenticular lens sheet. In this case, an image including the entire area of a predetermined width is taken on the line. Here, the imaging unit is a lens system that forms an image on the image receiving surface of the imaging unit. Examples of the light source of the illuminating unit include a fluorescent lamp light source and the like, but are not particularly limited thereto. The automatic inspection apparatus of the present invention uses both normal imaging and imaging by tilt imaging, and imaging by tilt imaging is performed on both side surfaces parallel to the moving direction of the moving lenticular lens sheet. From the camera. Thereby, the lenticular lens sheet can be imaged from at least three directions on the front side and both side faces of the lens, and when used as a screen, the lenticular lens having directivity in the light transmission direction can be moved in one direction. Rather than just making a judgment, defect detection is performed in a plurality of directions according to the directivity of light of the lens as much as possible.

Further, when used as a transmission type projection screen, uniformity of only transmitted light becomes a problem, so that defects inside and outside the lenticular lens are also reduced.
It is only necessary to judge a non-uniform portion of the transmitted light as a defect. In the present invention, an image is picked up only by the transmitted light, and the obtained image signal is processed to detect the defect. As the transmission type projection screen, one in which the lens directions are orthogonal to each other on the front and back of the screen, one in which the Fresnel lens is on the light input side, and one in which the lenticular lens is on the light output side,
Although various combinations of front and back shapes such as those shown in FIG. 6 are conceivable, basically, a lenticular lens (a semi-cylindrical convex lens) is provided on the light emitting surface side of the transmission type projection screen.
As long as it has an array, the device of the present invention can detect a defect. However, as a lenticular lens sheet for a transmission type projection screen most commonly used, as shown in FIG. 6, a lenticular lens (cave-shaped convex) is formed in the same direction on both the light emitting surface side and the illumination side (light source side). And a light-shielding portion (black stripe portion) is provided between the lenticular lenses (camel-shaped convex lens) array on the light-emitting surface side. In the case of this lens sheet, any of the defects A, B, and C at each position of the lens sheet can be detected by imaging from the above three directions obliquely from the front and both sides. For inspection of appearance defects of a lens sheet for an action screen, imaging from the above three directions is sufficient. or,
In the case of a lenticular lens sheet, as described above, most of the appearance defects are black defects, so only the black defects are generally regarded as appearance defects of the lenticular lens sheet for a transmission type projection screen and are inspected. Has been removed. However, as described below, defect detection involves:
Differentiation processing is performed on a signal obtained by imaging, and basically a defect that becomes locally bright can be detected. However, in the case of this defect, a change in appearance corresponding to the defect cannot be immediately determined. Often.

[0007] The image processing section in the defect inspection apparatus of the present invention specifies a defect by obtaining a change in a signal by performing a primary differentiation process or a secondary differentiation process on an image signal obtained by imaging. This differentiation process is performed by adding, subtracting, multiplying and dividing each sampling by using a filter having an element array, and as shown in FIG. 5, performing a differentiation process for each sequentially obtained line data. . Here, the pixel data P (x, y) obtained from the imaging means
And the spatial filter table W (i, j), P
A device that performs a product-sum operation of (x, y) and W (i, j) is called a filter, and a differential filter (spatial filter) as shown in FIG. 4 is used. As shown in FIG. 4B, (-1, +1)
By setting a spatial filter table (weight table) in (1), primary differentiation processing can be performed, and as shown in FIG.
-2, +1) spatial filter table (weight table)
Is set, the second derivative process in which the smoothing process is performed for two pixels in the X direction can be performed. The pixel data of the target pixel N is represented by X _n
Then, in the case of the second derivative processing in the pixel direction, the product-sum operation S of the pixel data and the spatial filter table is performed.
_n is (+1) × X _n−1 + (− 2) × X _n + (+ 1) ×
_{Xn + 1} . S _n (n is 2) obtained in this manner.
Slice processing is performed for the above integers) to detect defects. The second derivative in FIG. 5 performs a product-sum operation with a spatial filter table for each pixel data at the same position between lines obtained by sampling.
Line data obtained by a predetermined number of continuous samplings is accumulated, and the processing is performed between the line data. FIG.
In the case of (1), this processing is performed between 9 line data. However, every time new line data is sampled, this processing is always performed on 9 line data except for gradually older line data. In FIG. D _ij represents the pixel data at the i-th position in the j-th line data, and when the pixel data at the M-th position is multiply-accumulated between the lines, the secondary differentiation processing and the primary differentiation processing are respectively performed in FIG.
(B), as shown in FIG. 5 (c). Here, the line data includes a predetermined width on a straight line on the sheet surface across a width in a direction orthogonal to the moving direction of the lenticular lens sheet obtained by one or more linear region imaging units. This refers to data corresponding to the entire area of the predetermined width in the imaging data in one sampling of the visual field.

[0008]

According to the lenticular lens sheet defect inspection apparatus of the present invention having such a structure, it is possible to provide an automatic inspection apparatus for appearance defects which can be inspected in-line and which is compact and applicable to mass production. The defect inspection apparatus for a lenticular lens sheet according to the present invention captures an image from the light exit surface side of the sheet, and includes a normal imaging unit that captures an image from the front, and from both side surfaces parallel to the moving direction of the lenticular lens sheet. By additionally providing an image pickup unit for tilting photographing, it is possible to detect at least three defects of a lenticular lens having directivity of light.
Direction, so that detection is possible regardless of the position of the defect in the lens. By using only the transmitted bright-field illumination light for defect detection as illumination of each imaging means, based on the transmitted light as in the case of using as a transmissive screen, it is possible to detect a local non-uniform portion of the transmitted light. It is possible to make a judgment at a level close to practical use.
In addition, the arrangement of the imaging means, the transmitted bright field illumination means, and the imaging means is made easy, and the whole is made compact.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 of a lenticular lens defect inspection apparatus according to the present invention will be described below with reference to the drawings. FIG. 1 is a schematic view of the apparatus according to the first embodiment. FIG. 6 is a cross-sectional view of the lenticular lens sheet 4 used here. In FIG. 1, 1a, 1b, 1c are CCD line sensor cameras,
2a, 2b and 2c are lenses, 3 is a light source, 4 is a lenticular lens sheet (sample), 5 is an image processing device, and 6 is an imaging field of view of each CCD line sensor camera. The lenticular lens sheet 4, which is the test sample, moves at a constant speed in the direction of the arrow with the light emitting side in FIG. The lens 2a is a CCD line sensor camera 1a
Is adjusted so that an image of the sample 4 is formed on the image receiving surface of the sample 4, and the CCD line sensor camera 1a captures the entire imaging field 6 on a straight line in the width direction of the sample 4 from the front. At this time, the optical axis of the lens 2a passes through the center of the image receiving surface of the CCD line sensor camera 1a. The lens 2b is adjusted so that the CCD line sensor camera 1b forms the entire imaging field of view 6 from the left in FIG. At this time, the optical axis of the lens 2b passes through a position shifted from the center of the image receiving surface of the CCD line sensor camera 1b. The CCD line sensor camera 1b captures an image of the entire imaging field 6 on a straight line in the width direction of the sample. Further, the CCD line sensor camera 1c and the lens 2c also image the sample from the right in FIG. In FIG. 1, two lines extending from each lens represent a field of view taken by each imaging camera. The light source 3 illuminates the sample 4 with a transmitted bright field to each CCD line sensor camera. When performing an automatic inspection, the lenticular lens 4 moving at a constant speed is illuminated by the light source 3 and the CCD line sensor cameras 1a, 1b, 1c.
To image. By performing a line-to-line operation shown in FIG. 5 as image processing on the captured image signal, the same effect as the second-order differentiation and first-order differentiation processing by filtering shown in FIGS. 4A and 4B is obtained. This is called differential processing. After the calculation, of the secondary or primary differential signals, those exceeding a predetermined threshold are detected as defects. By the way, as for the black defect of the lenticular lens sheet, there are various positions of the defect in the lens as shown in FIG. The defect A is a defect that is visible from the front of the lenticular lens on the imaging surface side (light emitting surface side) and cannot be seen from an oblique direction. Is a defect that cannot be seen, and a defect C is a defect that can be seen from either the front or oblique direction of the lenticular lens on the imaging surface side (light emission surface side). In the present apparatus, the defect A was imaged by the camera 1a that images from the front, the defect B was imaged by the cameras 1b and 1c that imaged by tilting, and the defect C was imaged by the camera 1a that imaged from the front and cameras 1b and 1c that imaged obliquely. The image signal can be subjected to image processing and detected. In the inspection apparatus of the first embodiment (FIG. 1), a CCD line sensor camera, a lens, and a light source are arranged on one plane as shown in FIG. 3A, but as shown in FIG.
A line sensor camera and a lens may be arranged on a plurality of planes including the field of view 6 in FIG. 1 to image the sample. Even when the number of imaging cameras is increased by imaging from such different angles, the imaging cameras can be installed and imaged without interference between the imaging cameras. In FIG. 3, 21a,
21b and 21c are CCD line sensor cameras, 22a,
Reference numerals 22b and 22c denote lenses, and a plurality of CCD line sensor cameras and lenses are arranged side by side in the depth direction of the paper. 23a and 23b are light sources;
4b is a lenticular lens sheet.

Next, a second embodiment will be described. Embodiment 2 will be described below with reference to FIG. FIG. 2 is a schematic view of the apparatus according to the second embodiment. 2, 11a, 11b, 11c, 1
1d, 11e, 11f are CCD line sensor cameras, 1
2a, 12b, 12c, 12d, 12e and 12f are lenses, 13a and 13b are light sources, 14 is a lenticular lens (sample), 15 is an image processing device, 6a and 6b are CCDs
It is an imaging field of view of a line sensor camera. The lenticular lens 14 is inspected by moving at a constant speed with the light emitting surface side up in the direction of the arrow without vibration. Lens 1
2a and 12b are CCD line sensor cameras 1 respectively.
The image of the sample 14 is adjusted so as to form an image on the image receiving surfaces of 1a and 11b.
11b collectively images the entire visual field 6a on a straight line in the width direction of the sample 14 from the front. At this time, the optical axes of the lenses 12a and 12b pass through the centers of the image receiving surfaces of the CCD line sensor cameras 11a and 11b, respectively. Lens 12
c and 12d are CCD line sensor cameras 11c and 11d
Are adjusted so that the entire field of view 6b is shifted from the left in FIG. At this time, the lens 12
The optical axes of c and 12d pass through positions deviated from the centers of the image receiving surfaces of the CCD line sensor cameras 11c and 11d, respectively. CCD line sensor cameras 11c, 11d
Collects an image of the entire visual field 6b on a straight line in the width direction of the sample 14. Also, the CCD line sensor cameras 11e, 1
The lens 1f and the lenses 12e and 12f image the sample 14 from the right in FIG. In FIG. 2, two lines from each lens represent the field of view taken by each imaging camera. The light source 13a is connected to each CCD line sensor camera 11
The light source 13b illuminates the CCD line sensor cameras 11c, 11d, 11e, and 11f with the transmitted bright-field illumination for a and 11b. In the case of performing the automatic inspection, the lenticular lens 14 moving at a constant speed is illuminated by the light sources 13a and 13b and imaged by the CCD line sensor cameras 11a, 11b, 11c, 11d, 11e and 11f as in the first embodiment. As in the processing for the captured image signal, as in the first embodiment, the inter-line calculation shown in FIG. 5 is performed so that the filtering by the filtering using the spatial filter shown in FIGS. 4A and 4B is performed. Secondary differentiation and primary differentiation processing can be performed. Then, out of the calculated secondary or primary differential signals, those exceeding a predetermined threshold can be detected as defects. By dividing the region to be imaged on a plurality of straight lines in this manner, even when the number of imaging cameras is increased, the imaging cameras can be installed and imaged without interference with each other.
Further, even when the transmission light source has strong directivity in the moving direction of the sample and the method as shown in FIG. 3B cannot be taken, it is possible to take an image.

[0011]

By adopting the above-described structure, the present invention provides an in-line lenticular lens sheet, particularly a lenticular lens sheet for a transmission type projection screen, which is compatible with high quality and mass production. This makes it possible to provide a compact and inexpensive automatic visual inspection device that can be inspected by hand.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic view of an apparatus according to a second embodiment of the present invention.

FIG. 3 is a modification of the first embodiment of the present invention.

FIG. 4 is a diagram for explaining image processing in an embodiment of the present invention.

FIG. 5 is a diagram for explaining image processing in the embodiment of the present invention.

FIG. 6 is a view showing a defect of a lenticular lens sheet.

FIG. 7 is a diagram for explaining image pickup by tilt photographing;

[Explanation of symbols]

1a, 1b, 1c Imaging Camera 2a, 2b, 2c Lens 3a, 3b, 3c Light Source 4 Lenticular Lens Sheet 5 Image Processing Device 6 Imaging Field of View 11a, 11b, 11c, 11d, 11e, 11
f Imaging camera 12a, 12b, 12c, 12d, 12e, 12
f lens 13a, 13b, 13c, 13d, 13e, 13
f Light source 14 Lenticular lens sheet 15 Image processing device 6a, 6b, 6c Imaging field of view 21a, 11b, 11c Imaging camera 22a, 22b, 22c Lens 23a, 23b Light source 24a, 24b Lenticular lens sheet

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-168351 (JP, A) JP-A-1-260585 (JP, A) JP-A-7-181144 (JP, A) 158840 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01N 21/84-21/958 G01M 11/00-11/08

Claims (3)

(57) [Claims] 1. A lenticular lens sheet is moved at a constant speed in the lens direction of a lenticular lens while transmitting light is used to capture an image from a light emitting surface side by a linear area imaging unit, and a signal obtained by the imaging is subjected to image processing. An automatic inspection device that detects a black defect, and captures a predetermined width on a straight line on the sheet surface across a width in a direction orthogonal to a moving direction of the lenticular lens sheet from the front of the lenticular lens sheet. Then, the first lenticular lens sheet is moved to form a first linear region imager for imaging a predetermined region of the sample, and an image of the lenticular lens sheet is formed on the image receiving surface of the first linear region imager. The first imaging means and the lenticular lens obliquely from one side parallel to the moving direction of the lenticular lens sheet; A second linear area imaging unit that captures an image including a predetermined width on a straight line on the sheet surface across a width in a direction orthogonal to the sheet movement direction, and images a predetermined area of the sample by moving the lenticular lens sheet. When,
A second image forming means for forming an image of the lenticular lens sheet on the image receiving surface of the second linear area imaging means; and a lenticular lens sheet obliquely from the other side parallel to the moving direction of the lenticular lens sheet. A third linear area imaging means for imaging a straight line on the sheet surface including a predetermined width across a width in a direction orthogonal to the moving direction of the sample, and imaging a predetermined area of the sample by moving the lenticular lens sheet; And, a third imaging means for forming an image of the lenticular lens sheet on the image receiving surface of the third linear area imaging means, and for each linear area imaging means, illumination means for transmitting bright field illumination, Each of the imaging units includes an image processing unit that performs image processing on an image signal captured by the imaging unit, and the imaging by the first linear region imaging unit includes a second line so that a normal imaging can be performed. A lenticular lens, wherein the linear imaging unit and the imaging unit are arranged in association with each other so that imaging by the region imaging unit and the third linear region imaging unit can be performed by tilting imaging. Sheet defect inspection equipment. 2. The apparatus according to claim 1, wherein each of the linear area imaging means comprises one or a plurality of linear area imaging sections, and each of the imaging means is provided with a corresponding one of the linear area imaging sections. One or a plurality of image forming units are associated with one image forming unit, and each linear area imaging unit moves the lenticular lens sheet by adjusting the field of view of the one or more linear area image capturing units. A defect inspection apparatus for a lenticular lens sheet, wherein an image is taken on a straight line on a sheet surface across a width in a direction perpendicular to the direction, including an entire area of a predetermined width. 3. The defect inspection of a lenticular lens sheet according to claim 1, wherein the lenticular lens is a lenticular lens sheet for a transmission type projection screen having a lenticular lens array at least on a light exit surface side. apparatus.