JP2003158644A - Image pickup device for flat object with prescribed periodic pattern - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image pickup device that picks up an image of an object without causing moire stripe due to interference between the pitch of a prescribed periodic pattern and the pitch of CCD imaging elements and deterioration in the quality of an image in the case of extracting only the image with a prescribed periodic pattern from a flat object with a prescribed periodic pattern. SOLUTION: In the case of picking up an image of an object, after setting magnification of a prescribed periodic pattern object so as to make the pitch of the prescribed period pattern object in a Y direction to be an integer multiple of the pitch of a line CCD imaging element in the Y direction, a position of a camera is moved in a direction X and the object is repetitively picked up so that the pitch of the prescribed periodic pattern object in the direction X is an integer multiple of a distance of a moving projection image for one imaging period of the line CCD imaging element in the direction X. The image pickup device picks up the planar object with the prescribed periodic pattern and extracts only pixels of the prescribed periodic pattern from the picked-up image on the basis of the pitch and coordinates of the prescribed periodic pattern object registered in advance, a relative position of the camera and the object at imaging, and the coordinate of the prescribed periodic pattern image so as to re-compose only images of the same pattern.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup apparatus for a planar object having a fixed periodic pattern using a camera having a line CCD image pickup device.

[0002]

2. Description of the Related Art A conventional image pickup apparatus uses a camera having a two-dimensional CCD image pickup device and a zoom lens to set a constant period (pitch) of a planar object having a constant period pattern and a CC.
The zoom ratio is changed so that the 1-pixel cycle (pitch) of the D image pickup device is matched at a ratio of 1: 1 and images are collectively picked up to obtain an image.

In another image pickup device, a Y-direction of a plane object having a constant periodic pattern projected on a line CCD image pickup element is passed through a lens capable of switching the distance between the camera and the object in a plurality of steps. The optimum magnification is selected so that the pitch is approximately an integer multiple of the pitch of the image pickup element in the Y direction of the line CCD image pickup element, and the distance between the image pickup lens and the subject is fixed in order to obtain the above-mentioned magnification.

Next, while reading the output data from the line CCD image pickup device, a planar object having a fixed period pattern is moved by the same distance in the direction perpendicular to the line CCD image pickup device (X direction) and an image to be picked up is accumulated. , Is stored as two-dimensional intermediate data in the recording system section to be saved.

Only the pixels of the same pattern are extracted based on the coordinate position of the two-dimensional intermediate data and the luminance information data,
This is to synthesize and re-synthesize images having only the same pattern.

[0006]

When the camera having the above-mentioned two-dimensional CCD image pickup device is used, the distortion of the image on the CCD image pickup device due to the aberration of the image pickup lens causes the pitch of a constant periodic pattern in the entire image. , And the pitch of the CCD image pickup device cannot be matched, and moire fringes cannot be completely removed.

Also, the two-dimensional CC used for the camera used
There is a problem that the number of D image pickup devices limits the subjects having a fixed periodic pattern that can be taken.

When the line CCD image pickup device of another method is used, the pattern pitch of a subject having a fixed period pattern is not an integral multiple of the distance over which the projected image moves during one image pickup period of the CCD image pickup device. The phase varies in the X-direction image of the constant period pattern of the data.

Since the phase of the constant period pattern varies, it is not possible to highly accurately perform the operation of extracting only the image of the same pattern from the subject having the constant period pattern. Therefore, the quality of the desired image is deteriorated.

It is possible to set an object having a specific fixed period pattern to be an integral multiple of the pitch of the line CCD image pickup device. However, in general, the pitch of the subject having the constant period pattern is different for each subject, and in general, there is a problem that the pitch is not an integral multiple.

In order to solve the above problem, the X-direction pitch of the object having a constant period pattern is set by either increasing the clock speed for reading the image of the line CCD image pickup device or decreasing the stage moving speed. On the other hand, if the pitch ratio of the line CCD image pickup device in the X direction is increased (magnification of image pickup is increased), the accuracy of the calculation for extracting only the image of the same pattern from the subject having the constant period pattern is improved, but the line CCD image pickup device is improved. There is a technical and practical limit to the clock speed for reading the image of, and the stage moving speed cannot be reduced indefinitely. For this reason, image quality deterioration cannot be avoided within a practical range.

An object of the present invention to solve the above-mentioned problem is to interfere with the pitch of the constant period pattern and the pitch of the CCD image pickup device when extracting only the image of the same pattern from a planar object having the constant period pattern. An object of the present invention is to provide an apparatus for capturing an image without causing moire fringes and image quality deterioration. Another object is to solve the problem that affects the throughput of the device.

[0013]

The invention according to claim 1 of the present invention comprises: a base; a plurality of pillars whose lower ends are fixed to the base; and an upper end of an XY-direction drive unit fixed to the upper ends of the pillars. ,
A camera having a line CCD image pickup device fixed to the upper surface of the stage via a driving unit in the upper and lower Z directions, and an X direction and a Y direction for mounting a planar object fixed in the center on the base. Consists of a stage that moves to
A first drive mechanism that relatively moves the camera and the stage in parallel in the X and Y directions in order to capture an image of an arbitrary part of the planar object that the camera places on the stage, and mount the camera and the stage on the stage. Set the distance to the planar subject to Z
A second drive mechanism for moving in the direction, an illumination system section for illuminating a planar object arranged near the stage for transmission and reflection, opening and closing of a shutter of a camera arranged near the apparatus, and first and second The drive system of FIG. 2 has a control system unit that performs a predetermined operation, a recording system unit that stores and saves pre-registered data and a captured image, and a drive system unit that operates the entire apparatus. It is an imaging device of a planar object having a pattern.

Next, the invention according to claim 2 of the present invention is, in the image pickup device according to claim 1, a planar object having a constant periodic pattern projected onto a line CCD image pickup element through a lens during image pickup. The pitch Py in the Y direction is line C
The second driving mechanism is used to adjust and move the position of the camera up and down in the Z direction in order to adjust the imaging magnification so that it becomes an integral multiple of the pitch d in the Y direction of the CD image pickup device, and then the line CCD is passed through the lens. The pitch Px in the X direction of a planar object having a fixed periodic pattern projected on the image pickup device is an integral multiple of the distance w over which the projected image moves during one image pickup period in the X direction of the line CCD image pickup device. An image pickup apparatus for a planar object having a constant period pattern according to claim 1, wherein the first drive mechanism is used to move the position of the camera in the X direction to repeatedly perform image pickup.

According to a third aspect of the present invention, in the image pickup apparatus according to the second aspect, the pitch and the coordinate position of the planar object having a fixed periodic pattern registered in advance and the position of the camera at the time of image pickup. And, based on the relative position of the planar object having the constant period pattern and the coordinate position of the image of the constant period pattern, only the pixels of the same pattern are extracted from the captured image to be stored in the recording system unit, and are combined to be the same An image pickup apparatus for a planar object having a fixed periodic pattern according to claim 2, wherein an image of only the pattern is recombined.

The invention according to claim 4 of the present invention is any one of claims 1 to 3, wherein the camera and the subject in the image pickup device relatively move in a continuous or intermittent operation. It is an imaging device of a planar object having a constant period pattern of.

[0017]

With the image pickup apparatus of the present invention, it is possible to obtain an image in which the pitch of the constant period pattern of the planar object having the constant period pattern is an integral multiple of the pitch of the line CCD image pickup device. From this image, it is possible to obtain only the image of the same pattern by a simple calculation without deterioration of the quality accuracy. This makes it possible to extract only images of the same pattern and reconstruct an image composed of only images of the same pattern.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A detailed description will be given below of an embodiment of the present invention. FIG. 1 is a partial plan view showing an embodiment of an image pickup apparatus for a flat object having a constant period pattern according to the present invention.

A base 16, a plurality of columns whose bottom ends are fixed to the base, and an upper and lower Z-direction drive unit fixed to the upper ends of the columns in the X and Y directions so as to face the upper surface of the stage. A camera 12 having a line CCD image sensor fixed via a stage 15 and a stage 15 moving in X and Y directions on which a planar object fixed in the center of a base is placed.
It consists of and.

In order for the camera 12 to pick up an image of an arbitrary part of the planar object 13 placed on the stage, the first drive mechanism 10 for relatively moving the camera and the stage in parallel in the X and Y directions, and the camera. It is composed of a second drive mechanism 11 that moves the distance from the planar object placed on the stage in the vertical Z direction.

Next, the operation of the device is controlled by the control system 8 for opening and closing the shutter of the camera arranged near the device and for performing the predetermined operation of the first and second drive mechanisms.

Next, an illumination system section 7 for illuminating transmitted and reflected light on a planar object arranged in the vicinity of the stage, a recording system section 9 for accumulating and storing data to be registered in advance and captured images, and an apparatus. The image pickup device for a planar object having a constant periodic pattern, characterized by comprising a drive system section 6 for operating the whole.

In the image pickup apparatus of the present invention, first, the second driving mechanism determines the magnification for picking up the image in order to match both the pitches of the subject in the Y direction and the line CCD image pickup device in the Y direction.

Next, the first driving mechanism adjusts the object pitch in the X direction and an integral multiple of the distance over which the projected image moves during one image pickup cycle of the line CCD image pickup device in the X direction.
It controls an operation of repeating movement of a predetermined distance in the X direction.

In addition, the image pickup apparatus of the present invention has the roles of controlling the image pickup environment, storing the image to be picked up, and controlling the operation of the entire apparatus. The image capturing operation may be performed by continuously moving the image or by intermittently moving the image.

Next, FIG. 2 is a flow chart of a control system section for opening and closing the shutter of the camera of the image pickup apparatus and performing predetermined operations of the first and second drive mechanisms.

<S1> Pitch P of the subject 13 in the Y direction
y, the image pickup magnification is calculated so that it becomes an integral multiple of the pitch d in the Y direction of the line CCD image pickup device.

<S2> The distance between the subject and the camera is calculated in order to obtain the magnification of the above-mentioned image pickup.

<S3> The driving means of the second driving mechanism 11 is used to move the position of the camera to a predetermined position at the above distance.

<S4> The above-mentioned image pickup magnification is fixed.

<S5> Next, the pitch P of the subject in the X direction
x, a distance w that the projected image moves during one image pickup cycle of the line CCD image pickup element in the X direction, and a magnification Q of the image pickup,
The pitch Px of the subject in the X direction is an integral multiple of the distance w over which the projected image moves during one image capturing period of the line CCD image sensor in the X direction.
The moving distance wo in the direction is calculated.

<S6> The drive means of the first drive mechanism is used to move the camera to a predetermined position at which imaging is started.

<S7> The shutter of the camera is opened and closed once to take an image.

<S8> The captured image is stored and saved.

<S9> The drive means of the first drive mechanism is used to move the object in the X direction during one image pickup cycle of the camera to the movement distance wo.

<S10> If it is within the imaging range, s7
If it is out of the range to be imaged, the process proceeds to step s11.

<S11> The image pickup of the subject is completed.

As shown in FIG. 3, the field of view Do in the Y direction of a camera having a CCD image sensor is smaller than the width of the object,
If an image of the entire surface cannot be obtained, an image of the entire surface can be obtained by arranging cameras having a plurality of CCD image pickup devices in the width direction of the visual field.

As another method, as shown in FIG.
A step of obtaining a band-shaped image in the X direction by using the driving means of the first drive mechanism that moves in the direction Y, and then moving to the predetermined distance Do in the width direction of the visual field in the Y direction to obtain the next band-shaped image There is also a method of obtaining an image of the entire surface by the Andrepeat method.

S1 in the flow chart of the image pickup shown in FIG. 2 (pitch Py of the subject 13 in the Y direction, Y of the line CCD image pickup element)
The imaging magnification is calculated to be a positive multiple of the direction pitch d) will be described in detail with reference to FIG.

The integer value (N) is changed on the basis of the data of the pitch Py in the Y direction which is registered in advance and the data (d) of the pitch in the Y direction of the CCD image pickup device to satisfy the following expression (1). As described above, the imaging magnification (Q) is calculated, and one optimal magnification is selected by a standardized method. Q = (N * d) / Py ――――― (1)

In the image picked up by the magnification, the pitch Py in the Y direction of the subject becomes an integral multiple of the pitch d in the Y direction of the CCD image pickup element, and a highly accurate image can be obtained.

S5 in the flow chart of the image pickup shown in FIG. 2 (the pitch Px of the subject in the X direction, the distance w that the projected image moves during one image pickup cycle of the line CCD image pickup element in the X direction, and the magnification Q of the image pickup) Based on the above, the object during one imaging cycle of the camera is adjusted so that the pitch Px of the object in the X direction becomes a positive multiple of the distance w over which the projected image moves during one imaging cycle of the line CCD imaging element in the X direction. The moving distance wo in the X direction is calculated.)
Will be described in detail with reference to FIG.

Based on the data of the pitch Px in the X direction of the subject registered in advance, the data w of the distance that the projected image moves during one image pickup cycle of the CCD image pickup device in the X direction, and the fixed magnification Q of the image pickup. Then, by changing an arbitrary integer value (T), the moving distance (w
o) is calculated so as to satisfy the following expressions (2), (3) and (4). (K) is a real number calculated by calculation. k = (Px * Q) / w ――――― (2) k ≦ T <k + 1 ――――― (3) wo = Px / T ――――― (4)

In the image picked up by using the moving distance wo of the subject in the X direction during one image pickup cycle, the projected image moves while the pitch Px of the subject in the X direction is one image pickup cycle of the CCD image pickup element in the X direction. Since the distance is an integral multiple of w, an image with high accuracy can be obtained.

From the above detailed description, the magnification Q of the camera
And the moving distance wo of the subject in the X direction can be automatically calculated during one imaging cycle of the camera. Therefore, within the range of the Y direction and the X direction to be imaged, the subject pitch becomes an integer multiple of the pitch of the line CCD image sensor or the moving distance of the projected image during one imaging cycle, and the image to be imaged is X.
An image with high accuracy can be obtained in both the Y direction. (See display in Figure 3)

Next, the image stored in the recording means of the recording system section for accumulating and storing, the relative position of the camera at the time of image pickup, the subject, and the coordinate position of the planar subject having a predetermined periodic pattern registered in advance, It is easy to calculate the coordinate position where the stored image and the constant cycle pattern are contrasted by the calculation based on the pitch relationship of the constant cycle pattern.

Based on the above calculation, it is possible to reconstruct an image having the same pattern consisting of a fixed period pattern from the image stored in the recording means.

[0049]

EXAMPLES Next, the present invention will be described below with reference to specific examples.

<Embodiment 1> The camera 12 can be moved to an arbitrary position on the surface of the subject 13 facing each other by using the drive means of the first drive mechanism. The subject 13 is placed at a predetermined place on the stage, and is illuminated by a light source 14 for illumination installed near the upper surface or the lower surface of the subject 13. The illumination system unit is capable of capturing an image with transmitted or reflected light. The camera was moved to a predetermined position, and preparation for a predetermined lighting environment, for example, reflected light was completed.

Next, using the pitch in the Y direction of the constant period pattern of the planar object having the constant period pattern registered in advance, the image pickup magnification which is an integral multiple of the pitch of the line CCD image pickup device is calculated, and the moving distance is calculated. After the calculation, the distance between the lens and the subject was moved to a predetermined position by using the driving means of the second driving mechanism, and the magnification of image pickup by the lens was fixed.

Next, the driving means of the first driving mechanism shown in FIG. 3 moves to the imaging start point at the end of the subject.

Next, the time period of image pickup by the camera, the distance that the projected image moves during one image pickup period of the line CCD image pickup element in the X direction, and the X of the constant period pattern of the planar object having the constant period pattern. From the pitch in the direction and the magnification of the lens to be imaged, the distance that divides the pitch in the X direction of the constant cycle pattern of the object by an optimum integer is the distance that the object moves in the X direction during one imaging cycle of the camera. Calculate

Next, using the result of the above calculation, the distance the subject moves in the X direction, the time period for one image pickup, and the shutter opening / closing operation are instructed. According to the above instruction, the image is taken by opening and closing the shutter once, and the movement in the X direction up to the predetermined distance is executed.

By repeating the above operation, the images to be picked up are sequentially transmitted. Next, an image of the entire subject was recorded by using the means for accumulating and storing in the recording system section in order. The subject,
The position coordinates of the captured image could be saved with the same accuracy.

FIGS. 4A and 4B are schematic views of an example of the obtained image. The desired constant cycle pattern to be obtained from the camera position at the time of image pickup and the pitch of the constant cycle pattern of the subject registered in advance. It is obtained by calculating the position coordinates in the image.

For example, in FIG. 4A, it was found by calculation that a desired constant period pattern is recorded with a width of 2 dots from the 5th dot in the X direction and a pitch of 6 dots. A schematic diagram in which only dots corresponding to a desired constant period pattern are extracted based on this information is a schematic diagram for explaining a state in which 5 dots and 6 dots are extracted for each pitch as shown in FIG. 4B. .

Next, as shown in FIG. 5C, an image of the same pattern composed of only the constant period pattern was reconstructed by filling in the blank portion of 1 bit to 4 bits for each pitch.

FIGS. 5 (a) to 5 (c) are schematic views showing an example of an image obtained from a subject in which a fixed period pattern is two-dimensionally arranged in a staggered pattern.

Even in this case, as shown in FIGS. 7A, 7B and 7C, the same pattern image of only the constant period pattern portion was reconstructed by the same procedure.

[0061]

According to the image pickup apparatus of the present invention, it is possible to obtain an image in which the pitch of the fixed-cycle pattern of the subject is an exact multiple of the pitch of the CCD image pickup element, and the fixed-cycle pattern is picked up from the image. It is possible to easily and accurately obtain the displayed image portion by a simple calculation. As a result, it is possible to extract only the image of the fixed period pattern portion and reconstruct the image composed of the image of the fixed period pattern portion only. As described above, it is possible to obtain a high-quality image without moire fringes and deterioration of image quality. Further, the provision of this device can maintain the throughput of the device at a high level.

[Brief description of drawings]

FIG. 1 is a partial perspective side sectional view of an example of an image pickup apparatus for a planar object having a constant period pattern of the present invention.

FIG. 2 is a flow chart of image pickup used in the image pickup apparatus of the present invention.

FIG. 3 is a schematic view of an example for explaining image pickup of one image pickup cycle of the image pickup apparatus of the present invention.

4A to 4C are schematic diagrams of an example of an image captured using the image capturing apparatus of the present invention, and FIG. 4A is an entire image,
(B) is an image in which a specific identical pattern is extracted, and (c)
Only the same pattern is an image reconstructed.

5A to 5C are schematic diagrams of an example of an image captured by the image capturing apparatus of the present invention, and FIG. 5A is an entire image,
(B) is an image in which a specific identical pattern is extracted, and (c)
Only the same pattern is an image reconstructed.

[Explanation of symbols]

1 ... Constant cycle pattern 2 ... Planar subject 3 ... Line CCD image sensor 4 ... Image 5 ... same pattern 6 ... Drive system section 7 ... Lighting system section 8 ... Control system section 9: Recording system section 10 ... First drive mechanism 11 ... Second drive mechanism 12 ... Camera 13 ... Subject 14 ... Lighting 15 ... Stage 16 ... Base

Claims (4)

[Claims] 1. A base, a plurality of pillars whose lower ends are fixed to the base, and an upper and lower Z-direction driving unit fixed to the upper ends of the pillars in the XY directions so as to face the upper surface of the stage. A camera having a line CCD image pickup device fixedly attached via a section, and a stage moving in X and Y directions on which a flat object fixedly mounted on the base is placed, and the camera is mounted on the stage. A distance between the first drive mechanism that relatively moves the camera and the stage in parallel in the X and Y directions in order to image an arbitrary part of the planar object to be placed, and the distance between the camera and the planar object to be placed on the stage. Drive mechanism for moving the camera up and down in the Z direction, an illumination system unit for illuminating a planar object to be transmitted and reflected near a stage, opening and closing of a shutter of a camera arranged near the device, and a first When, The second drive mechanism includes a control system unit that performs a predetermined operation, a recording system unit that stores and stores previously registered data and a captured image, and a drive system unit that operates the entire device. An imaging device for a planar object having a periodic pattern. 2. The image pickup apparatus according to claim 1, wherein a Y-direction pitch Py of a planar object having a constant period pattern projected onto a line CCD image pickup element through a lens at the time of image pickup is of the line CCD image pickup element. The second drive mechanism is used to adjust the position of the camera up and down in the Z direction in order to adjust the imaging magnification so as to be an integral multiple of the pitch d in the Y direction, and then on the line CCD image sensor via the lens. The first driving is performed so that the pitch Px in the X direction of the projected planar object having the fixed periodic pattern becomes an integral multiple of the distance w over which the projected image moves during one imaging period of the line CCD image sensor in the X direction. 2. The apparatus for imaging a planar object having a fixed periodic pattern according to claim 1, wherein the position of the camera is moved in the X direction by using a mechanism to perform repeated imaging. 3. The image pickup apparatus according to claim 2, wherein the pitch of the planar object having a constant period pattern and its coordinate position registered in advance, the position of the camera at the time of image capturing, and the relative position of the planar object having the constant period pattern. Based on the position and the coordinate position of the image of the fixed period pattern, only the pixels of the same pattern are extracted from the captured image stored in the recording system unit, and the images are combined to re-synthesize the image of only the same pattern. An image pickup apparatus for a planar object having a constant periodic pattern according to claim 2. 4. The planar object having a constant periodic pattern according to claim 1, wherein the camera and the object in the image pickup device are moved continuously or intermittently. Imaging device.