JP2004094323A - Image inputting method and device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To automatically perform the light shielding of an area whose transmissivity is higher than a work area when imaging an object to be inspected where a work whose transmissivity is lower than that of a sheet-shaped substrate whose transmissivity is high is arranged at a predetermined position of the substrate under transmitted illumination by a line sensor camera. <P>SOLUTION: In this image inputting device for allowing the object where the work whose transmissivity is lower than that of the substrate is arranged at the predetermined position of the sheet-shaped substrate whose transmissivity is high pass between transmissive illumination and a line sensor camera 12 in order to image the object by the camera, the transmitted lights passing through an area outside the work positioned on a cross line where the optical axis of the camera crosses the object are automatically shielded by putting light shielding plates (1)(2)(3)(6)(7)(11)(12) in a high luminance area into light shielding state where the light shielding plates cross the optical axis based on luminance information acquired by imaging the object by the camera. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an image input method and apparatus, in particular, an object to be inspected in which a workpiece having a lower transmittance than a substrate is disposed at a predetermined position on a sheet-like substrate having a high transmittance, between a transmission illumination and a line sensor camera. The present invention relates to an image input method and apparatus suitable for applying when inputting an image of a region in a work by taking an image with the line sensor camera while passing through the image sensor.
[0002]
[Prior art]
Now, as shown in FIG. 11, the inspection object to be image-inputted has a pattern such as a printed matter in which a pattern is printed at a predetermined position on a sheet-like substrate S made of a transparent film. It is assumed that the inside of the work inside the work Wa has extremely low light transmittance as compared with the outside of the work corresponding to the surrounding area of the work Wa.
[0003]
As shown in FIG. 12A, when the inspection object (input object) W is viewed from the front, the line sensor positioned above is illuminated by the transmission light source 10 positioned below. Consider a case where the camera 12 captures an image with a range equal to or larger than the width of the work Wa as a visual field.
[0004]
When an image is captured by the line sensor camera 12 in this manner, an example of the relationship between the brightness values when light is received by the image sensor 12A provided in the camera 12 in correspondence with the inspection object W in FIG. As shown in FIG. 7B, there is a region outside the work with higher transmittance than inside the work. This is an example of a case where an image is captured under transmitted illumination with a sufficient amount of light, and the boundary portion of the work in the input image shows a value higher than the original luminance value indicated by the two-dot chain line as indicated by a circle. Therefore, the dynamic range, which is the range between the maximum value and the minimum value of the luminance value in the work, cannot be widened, so that accurate image input cannot be performed. This phenomenon becomes remarkable especially when the light amount outside the work exceeds the saturation light amount of the image sensor, as the luminance value is constant at the maximum value 255 (in the case of 8 bits) in the figure. Therefore, in order to prevent such a phenomenon from occurring, the amount of transmitted illumination is set so that the amount of transmitted light outside the work is smaller than the amount of saturated light of the image sensor, as shown in FIG. Then, the luminance value was set to be smaller than the maximum value of 255.
[0005]
[Problems to be solved by the invention]
However, when the light amount of the transmitted illumination is set to be small as described above, as shown by the circle in FIG. However, since the maximum luminance value in the input image is lower than the full range (255) by a in the figure, the maximum luminance value in the region in the work is also reduced by about the same, and the dynamic range is narrowed. Ideally, the dynamic range should be as wide as shown in FIG. 2D, which corresponds to the two-dot chain line in FIG. 2B, but if the width becomes narrower, the density difference of the input image becomes smaller. There is a problem that accuracy is reduced.
[0006]
SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problem, and a line sensor camera is provided for inspecting an object to be inspected in which a work having a lower transmittance than a substrate is arranged at a predetermined position on a sheet substrate having a high transmittance. When capturing an image under transmitted illumination, an area having a higher transmittance than the work area can be automatically shaded, so that the work area can be image-input with a sufficiently large amount of illumination. It is an object to provide an image input method and apparatus using a sensor camera.
[0007]
[Means for Solving the Problems]
The present invention provides an inspection method in which a workpiece having a transmittance lower than that of a substrate is disposed at a predetermined position on a sheet-like substrate having a high transmittance, while passing the inspection target between the transmission illumination and the line sensor camera. An image input method of capturing an image with a sensor camera, wherein the optical axis of the line sensor camera is an illumination light incident on a region outside the work located on an intersection line intersecting with the inspection target or a transmitted light passing through the region. The present invention has solved the above-mentioned problem by automatically shutting off the inspection object based on image information obtained by imaging the inspection object by the line sensor camera.
[0008]
The present invention also provides an inspection object in which a workpiece having a lower transmittance than the substrate is arranged at a predetermined position on a sheet-like substrate having a high transmittance, while passing between the transmitted illumination and the line sensor camera. An image input apparatus for capturing an image with the line sensor camera, wherein the optical axis of the line sensor camera is incident on an area outside the work located on an intersection line intersecting with the inspection object, or transmitted through the area. The object is similarly solved by providing a light shielding device that automatically blocks light based on image information obtained by imaging the inspection object with the line sensor camera.
[0009]
That is, in the present invention, as shown in FIGS. 1A and 1B corresponding to FIGS. 12A and 12B, a CCD or the like constituting an image sensor 12A of the line sensor camera 12 is shown. Of the unit element is saturated beyond the amount of charge that can be accumulated when the camera 12 is scanned, that is, the position in the scanning direction of the unit element whose luminance value has reached the maximum value (Max in the figure). The range (number) is determined, and based on the determination result, the light shielding plate 16 can be automatically arranged outside the area of the workpiece Wa as shown in FIG. 2A. As a result, it is possible to prevent the influence of the saturated light amount area from being affected without any trouble, and it becomes possible to input an image of the work area under a sufficiently large amount of illumination light. An image with such a wide dynamic range can be obtained, and image accuracy can be improved.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
FIG. 3A is a front view showing a hardware outline of an image input apparatus according to an embodiment of the present invention, and FIG. 3B is a plan view thereof.
[0012]
As shown in FIG. 3A, the image input device of the present embodiment is a printed matter in which a picture (work) Wa is printed at a predetermined position on a transparent film (sheet-like substrate) S conveyed in a direction perpendicular to the paper surface. Is an inspection object (input object) W, a linear transmission light source 10 composed of a fluorescent lamp is provided below the object W, and a line sensor camera 12 is provided above the object W. It is configured to be arranged in parallel, that is, perpendicular to the transport direction of the inspection object W.
[0013]
In the inspection object W, a work Wa of a predetermined size, which is a print pattern, is multi-faced at a predetermined interval on the transparent film S as shown in FIG. It is assumed that the inside is the inside of the work, and the other area including only the transparent film is outside the work.
[0014]
The image input device according to the present embodiment includes a light-shielding device 14. The light-shielding device 14 is partially omitted in FIG. 3A, but as shown in FIG. The camera 12 has a large number of light shielding plates 16 arranged side by side along an intersecting line K (corresponding to the scanning direction of the camera) where the optical axis of the camera 12 intersects the inspection object W over a range beyond the field of view of the camera 12. are doing.
[0015]
As shown in FIG. 4, the light-shielding plate 16 is provided with a rotation shaft 18 disposed in a direction orthogonal to the conveyance direction, and is rotated around the rotation shaft 18 so that the front end of the light-shielding plate 16 is a line sensor. It is possible to switch between two states: a lowered state 16A that intersects with the optical axis of the camera 12, and an raised state 16B that does not intersect as indicated by a two-dot chain line. Air shields (actuators) 20 are disposed on the respective light shielding plates 16 as shown in a perspective view in FIG. 5, and the corresponding light shielding plates 16 are moved downward by moving the piston rods 20A of the respective air cylinders 20. By pushing down the rear end portion of the plate 16, it is possible to switch from the light shielding state 16A to the non-light shielding state 16B.
[0016]
In the light-shielding device 14, when the inspection object W is imaged by the line sensor camera 12, the light-shielding plate 16A in a state in which the optical axis is blocked is provided outside the work of the object W, By setting the light shielding plate 16B in a raised state so as not to block the optical axis and by arranging the images as shown in FIGS. 3A and 3B, transmitted light from only the region of the work Wa can be reduced. The light is incident on the line sensor camera 12. For this purpose, the individual light-shielding plates 16 are formed of metal subjected to light reflection prevention processing, for example, each having a width of 4 mm and a thickness of 20 mm in the juxtaposition direction, and can be spread without gaps. It has become. In particular, when it is desired to input the entire area in the work with high accuracy, it is desirable to reduce the width value as much as possible in order to prevent the light shielding plate from entering the inside of the work.
[0017]
In the present embodiment, the light shielding device 14 further includes a control system as shown in FIG. That is, a luminance signal (image signal) output from the line sensor camera 12 is input to a computer 24 which is a control operation unit via a signal processing board 22. Based on the luminance signal, the position coordinates of a unit element (not shown) in the image sensor 12A corresponding to a region having a high transmittance and the range (number) thereof are calculated, and the result is output to the sequencer IO unit via the RS232C serial interface. 26, the unit 26 drives the air cylinder 20 corresponding to the calculation result, and the light shielding plate 16 at the corresponding position can be automatically controlled to the light shielding state 16A.
[0018]
Next, the control algorithm of the present embodiment will be described with reference to the flowchart shown in FIG.
[0019]
When the product type of the product to be inspected W is changed (step 1), the light shielding is released so that all the light shielding plates 16 are in the non-light shielding state 16B (step 2). In this state, inspection is started by transporting a new type of inspection object W, and the line sensor camera 12 is scanned to input luminance information (signal) for one scan as image information (step 3).
[0020]
Next, based on the input luminance information, a saturated portion of the image sensor 12A of the line sensor camera 12 (an element region having a large transmittance) is detected (step 4), and the detected scanning direction of the image sensor 12A is detected. The corresponding light shielding position (the position of the light shielding plate 16 to be in the light shielding state 16A) is determined from the position of the unit element in (5), the determined light shielding position and its width (range) are calculated, and a memory (not shown) (Step 6), and the light shielding plate 16 at the determined light shielding position is set to the light shielding state 16A by operating the corresponding air cylinder 20 (Step 7). During the continuation of the inspection, the processes of the above steps 3 to 7 are repeated.
[0021]
The algorithm of the present embodiment uses an 8-bit line sensor camera 12 (saturation luminance value = 255), and the light shielding device 14 has 12 light shielding plates 16 for convenience, using FIG. This will be described more specifically.
[0022]
Assuming that the luminance information (image information) input as shown in FIG. 8A in step 3 is as shown in FIG. 8B, in step 4, the input signal is binarized by using the luminance value 250 as a threshold to obtain The H (high) level portion of the binary data shown in FIG. In step 5, the value of the X coordinate (the position of the unit element) of the image sensor 12A corresponding to the scanning direction and the number (1) of the light shielding plate shown in FIG. Using the relations (1) to (12), the specific position of the light shielding plate 16 to be shielded from light is determined. In this example, the light shielding plates 16 of (1), (2), (3), (6), (7), (11), and (12) are determined as the light shielding positions. As described above, the actual position is determined by associating the coordinates shown in the luminance profile with the light shielding plate 16 in advance for each sheet.
[0023]
In the present embodiment, as shown in the image of FIG. 9A, when the inspection of the inspection target W is continued while the light is shielded by the light shielding plate 16 of (5) and (6), the target W Can be handled by changing only the light shielding position to (6) and (7) without changing the light shielding width as shown in FIG. That is, in the case of the same type, since the light-shielding width does not usually change, even if a new saturated portion suddenly appears in the luminance information input from the line sensor camera 12, it is necessary to shift only the light-shielding position without changing the light-shielding width. Can respond. However, since it is conceivable that the opening may be widened, such a case can be similarly handled by changing the light shielding width.
[0024]
In the present embodiment, as shown in the perspective view of FIG. 10, a hoop (band-shaped product) continuously printed on a transparent film is printed on a hoop (band-shaped product), in which a picture is multifaceted in the width direction. In the case of inputting an image, the corresponding light shielding plate 16 is automatically operated for the transparent opening between the patterns by the method described with reference to FIG. Can be reliably shielded from light.
[0025]
According to the present embodiment described above, the saturated portion of the luminance is detected based on the luminance information input by the line sensor camera 12, and the numerical control is performed based on the detection result. , And the light-shielding operation can be automatically performed. Therefore, light can be shielded following the transport behavior of the inspection object W, and an image can always be input under the same conditions even when meandering occurs.
[0026]
In addition, since the operation of the corresponding light shielding plate 16 can be performed automatically, it is possible for the operator to determine the light shielding width by looking at the state of the work and to cause individual differences as in the case of manual operation. Can be prevented. Further, since the maintenance work can be simplified and no human intervention is required, there is an advantage that generation of dust can be reduced.
[0027]
As described above, the present invention has been specifically described. However, the present invention is not limited to the above-described embodiment, and can be variously modified without departing from the gist thereof.
[0028]
For example, although the case where the light shielding device 14 is disposed above the inspection object W to block transmitted light has been described, the light shielding device 14 may be disposed below to block illumination light.
[0029]
Further, the example in which the light shielding plate 16 rotates about the rotation shaft 18 has been described. However, the present invention is not limited to this, and a mechanism in which the light shielding plate 16 moves forward and backward with respect to the optical axis position is adopted. You may.
[0030]
Further, in the embodiment, the case where the work is a printed picture has been described. However, the present invention is not limited thereto, and there is no particular limitation as long as the work has optically similar properties.
[0031]
【The invention's effect】
As described above, according to the present invention, an object to be inspected in which a work having a lower transmittance than the substrate is arranged at a predetermined position on a sheet-like substrate having a high transmittance is imaged under transmission illumination by a line sensor camera. At this time, an area having a transmittance higher than that of the work area is automatically shielded, so that the amount of illumination light can be sufficiently increased to input an image of the work area.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a relationship between imaging by a line sensor camera in a non-light-shielded state and obtained luminance information. FIG. 2 is an explanatory diagram showing a relationship between imaging by a line sensor camera in a light-shielded state and obtained luminance information. FIG. 3 is a front view and a plan view schematically showing an image input device according to an embodiment of the present invention. FIG. 4 is a schematic side view showing a relationship between a light-shielded state and a non-light-shielded state of a light-shielding plate. FIG. 6 is a partial perspective view showing a relationship between a plate and a driving air cylinder. FIG. 6 is a control block diagram showing a main part of a control system of the image input device of the present embodiment. FIG. 7 is a flowchart showing an algorithm of the present embodiment. 8 is an explanatory diagram showing the correspondence between the luminance information obtained by the line sensor camera and the determined light blocking position. FIG. 9 is an explanatory diagram showing an example of a control method when the inspection object is meandering. FIG. 10 is an image of the inspection object. Show state image Schematic perspective view and FIG. 11 is an explanatory diagram showing a partial plan view and FIG. 12 conventional problem indicating characteristics of the inspection object EXPLANATION OF REFERENCE NUMERALS
DESCRIPTION OF SYMBOLS 10 ... Transmission light source 12 ... Line sensor camera 14 ... Shading device 16 ... Shading plate 18 ... Rotating shaft 20 ... Air cylinder W ... Inspection object Wa ... Picture (work)
S: Transparent film (sheet-like substrate)

Claims (5)

An object to be inspected, in which a workpiece having a lower transmittance than that of the substrate is disposed at a predetermined position on a sheet-like substrate having a high transmittance, is imaged by the line sensor camera while passing between the transmission illumination and the line sensor camera. Image input method,
The line sensor camera captures the inspection object by the line sensor camera, for illumination light incident on a region outside the work positioned on an intersection line intersecting with the inspection object or transmitted light passing through the region. An image input method characterized in that the cutoff is automatically performed based on image information obtained as a result. The image input method according to claim 1, wherein the blocking of the illumination light or the transmitted light is performed by operating a light shielding plate having a predetermined width based on the image information and arranging the light on the intersection line. An object to be inspected, in which a workpiece having a lower transmittance than that of the substrate is disposed at a predetermined position on a sheet-like substrate having a high transmittance, is imaged by the line sensor camera while passing between the transmission illumination and the line sensor camera. An image input device,
The line sensor camera captures the inspection object by the line sensor camera, for illumination light incident on a region outside the work positioned on an intersection line intersecting with the inspection object or transmitted light passing through the region. An image input device, comprising: a light-shielding device that automatically blocks light based on image information obtained by performing the above operation. 4. The light shielding device according to claim 3, wherein a light shielding plate that can be switched between a light shielding state intersecting with the optical axis and a non-light shielding state not intersecting is arranged along the intersection line. An image input device according to claim 1. The light-shielding plate is axially inserted into a rotation shaft provided in the intersection line direction, and is turned around the rotation shaft based on the image information to be switched between a light-shielding state and a non-light-shielding state. The image input device according to claim 4, wherein:

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