JPH11142344A - Method and apparatus for measuring perspective distortion - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a device by moving one of an object to be measured, an image pickup means, or a cylindrical screen, changing a location of inspection of the object to be measured, driving the cylindrical screen to rotate in synchronization with a travelling speed of a location of inspection, and sequentially acquiring light reception data on the object to be measured in a predetermined measurement range. SOLUTION: An object to be measured 12 is transferred at a constant speed by a conveyor device 14, and a cylindrical screen 10 is rotated in synchronization with the transferring speed. Next, a location of inspection of the object to be measured 12 is changed, the screen 10 is driven to rotate in synchronization of the moving speed of the location of inspection, and transmitted light through the object to be measured 12 is received by a line sensor camera 16. As a pattern 20 on the peripheral surface of the screen 10 is two-dimensionally expanded by moving the object to be measured 12, it is possible to acquire image data on the object to be measured 12 in an inspection region sequentially. On the basis of image data acquired in this way. transmission distortion in the object to be measured 12 is evaluated and measured. By this, it is possible to satisfy a function equivalent to a large screen.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and an apparatus for measuring perspective distortion, and more particularly, to observing light transmitted through a light-transmitting object such as a glass plate to determine a defect and a degree of distortion of a material. The present invention relates to a method and an apparatus for measuring a perspective distortion to be measured.

[0002]

2. Description of the Related Art As a technique for measuring the distortion of a light transmitting material such as a window glass for an automobile, for example, Japanese Patent Application Laid-Open No. 7-200
No. 59, Japanese Patent Application Laid-Open No. 7-120402 and the like disclose techniques. As shown in FIG. 4, a screen 2 having a predetermined contrast pattern such as a checker pattern is installed behind an object 1 such as glass as shown in FIG.
An imaging device 4 such as a CCD camera is installed in front of the DUT 1, and the screen 2 is photographed through the DUT 1 by the imaging device 4, and the perspective distortion of the DUT 1 is determined from the photographed data. It is to be measured.

[0003]

However, in the above-mentioned conventional measuring method, it is necessary to arrange a screen larger than the object to be measured in order to guarantee the whole inspection area. When performing a full inspection, a large screen must be installed, which poses a problem in terms of installation space.

[0004] The present invention has been made in view of such circumstances, and has the same function as a large screen,
It is an object of the present invention to provide a method and an apparatus for measuring a perspective distortion which can reduce the size of the apparatus.

[0005]

According to the present invention, in order to achieve the above object, a screen having a predetermined regular pattern is provided behind a light-transmitting DUT, while a screen having a predetermined pattern is provided on the front side of the DUT. In the method of receiving the transmitted light transmitted through the object by this light receiving device, and measuring the perspective distortion of the object based on the obtained light receiving data, a cylindrical or belt as the screen Using an annular screen, at least one of the object, the imaging means, and the screen is moved to change the inspection position of the object, and the annular screen is tuned to the moving speed of the inspection position. It is characterized in that it is driven to rotate, and light receiving data of a predetermined measurement range of an object to be measured is sequentially acquired.

In the method invention, a method for evaluating and measuring the distortion of the measured object from the received light data may be appropriately selected. Further, in order to provide an apparatus embodying the method of the present invention, the present invention provides a cylindrical or belt-shaped annular screen having a predetermined regular pattern, which is installed on the back side of a light-transmitting DUT. Screen driving means for rotating the annular screen in the circumferential direction, disposed on the near side of the object to be measured and opposed to the annular screen,
An imaging unit that captures an image of the regular pattern of the annular screen that has passed through the object to be measured, and at least one of the object to be measured, the imaging unit, and the annular screen is moved to change an inspection position of the object to be measured. Inspection position moving means, control means for controlling a screen driving means so as to rotate the annular screen in synchronization with a moving speed of the inspection position by the inspection position moving means, and image data obtained by the imaging means. And an image processing device for evaluating the transmission distortion of the object under test.

According to the present invention, two-dimensionally developed screen image (pattern) data can be captured by moving the inspection position and rotating the screen. This makes it possible to reduce the size of the screen while satisfying the same functions as those of a large flat screen screen, and to save the space of the apparatus. In addition, by adjusting the rotation speed of the screen, the form of the pattern can be substantially changed. Even though the pattern is actually one regular pattern, the detection sensitivity is increased or decreased by increasing or decreasing the rotation speed of the screen. Can be changed.

In particular, a one-dimensional line sensor camera is used as an imaging means, and the one-dimensional line sensor camera and the annular screen are fixedly arranged at a predetermined position, and the object to be measured is oriented in a direction perpendicular to the axis of the annular screen. By adopting the configuration for transport, the configuration of the apparatus is also simplified.
In addition, if this configuration is adopted, the field of view of the camera becomes one line, so that the adjustment is easy, and the area where the uniformity of the light source for illuminating the screen is to be guaranteed is linear, so that the device can be easily implemented. It is.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of a method and an apparatus for measuring perspective distortion according to the present invention will be described below in detail with reference to the accompanying drawings. FIG. 1 is a perspective view showing a configuration of a perspective distortion measuring device according to an embodiment of the present invention. This measuring device mainly includes a cylindrical screen 10 and a device under test 12.
It is composed of a conveyor device 14, a line sensor camera 16, an image processing device 18, and the like for transporting barrel glass (in this example, a windshield of an automobile).

A regular light / dark contrast pattern (for example, a checker pattern) 20 is formed on the outer peripheral surface of the screen 10, and a tubular light source lamp 22 is provided inside the cylindrical portion. Note that the regular pattern is not limited to the checker pattern, but may be a lattice pattern, a zigzag pattern, or the like, and is appropriately selected according to the method of measuring the perspective distortion employed by the apparatus.

The cylindrical screen 10 is disposed so that its longitudinal direction is perpendicular to the direction of transport of the object 12 to be measured, and has a shaft above a conveyor device 14 via a support member (not shown in FIG. 1). It is supported so that it can rotate around. Although not shown, a screen driving mechanism for rotating the screen 10 by driving a motor is provided. A motor for rotating the screen 10 is controlled by a control device (not shown) so that the rotation speed of the screen 10 can be adjusted arbitrarily.

The conveyor device 14 has two rows of transport sections 14A and 14B for horizontally supporting the DUT 12, and an endless belt 24 wound around each of the transport sections 14A and 14B is a motor (not shown). It is designed to rotate by the driving force of. The device under test 12 is placed on the transport units 14A and 14B, and is transported leftward in the drawing by rotation of the belts 24 and 24 driven by a motor.

The motor of the conveyor 14 is controlled by a control device (not shown) so that the transport speed of the object 12 can be arbitrarily adjusted. The line sensor camera 16 has sensors for a plurality of pixels in a direction orthogonal to the transport direction of the device under test 12,
Is fixed at a predetermined position below. Further, it has an angle of view that captures the entire area of the device under test 12 in the width direction or a portion including a predetermined target region.

The image processing device 18 includes a computer 26,
A monitor television 28, a power supply device 30, and a mouse 32, which is a computer operation input unit, are used to evaluate and measure the perspective distortion of the DUT 12 by a known image processing method based on image data captured by the line sensor camera 16. . FIG. 2 shows an example of the appearance of a perspective distortion measuring apparatus employing the configuration shown in FIG. Cylindrical screen 1
Numeral 0 is rotatably supported on the upper part of a gate-shaped frame, and a tubular light source lamp 22 is fixed inside the screen 10.

The conveyor device 14 has a substantially rectangular frame 34. Conveying belts 24 are wound around right and left sides via rollers 36, 36, respectively. A parallel row of conveyor belts is formed. The conveyor device 14 and the screen 10 are arranged in a substantially T-shape such that the transport direction of the conveyor device 14 is orthogonal to the axis of the screen 10.

The line sensor camera 16 is a conveyor device 1
4 is fixed via a support member (not shown), and the optical axis of the camera is adjusted so that light from the cylindrical screen 10 enters the camera from obliquely forward and upward. In this manner, by inclining the inspection optical axis with respect to the DUT 12, a large perspective distortion appears, and the distortion can be easily observed.

Next, the operation of the above-described apparatus for measuring a perspective distortion configured as disclosed in Japanese Patent Laid-Open Publication No. HEI 10-208400 will be described. The device under test 12 is transported by the conveyor device 14 at a constant speed, and the screen 10 is rotated in synchronization with the transport speed. At this time, the rotation speed of the screen 10 is
In consideration of the scanning cycle of No. 6, control is performed so that the regular pattern 20 drawn on the peripheral surface of the screen 10 is evenly captured.

The inspection position of the object 12 is changed by the conveyor device 14, and the transmitted light of the object 12 is transmitted to the line sensor while rotating the screen 10 in synchronization with the moving speed of the inspection position. Camera 16
To receive light. The inspection position of the DUT 12 captured by the line sensor camera 16 is changed by the movement of the DUT 12 by the conveyor device 14, and the screen 10 is rotated in synchronization with the movement, thereby rotating the cylindrical screen 10. Is developed two-dimensionally, and image data of the entire area of the DUT 12 or a predetermined inspection area can be sequentially acquired.

In this way, the image can be captured as a two-dimensionally developed perspective image, and based on the acquired image data, the transmission distortion of the object to be measured is evaluated and measured using a known image processing technique. As described above, by rotating the cylindrical screen 10 in synchronization with the translational movement of the device under test 12, it is possible to fulfill the same function as a large screen screen, and to reduce the size of the screen and save the space of the apparatus. Can be planned. In addition, since the transport operation of the DUT 12 and the rotation of the screen are synchronized, the image is taken in as a two-dimensionally developed image. And can be applied to a measuring device for a long object.

By adjusting the rotation speed of the screen 10, the appearance of the regular pattern 20 in the circumferential direction (the width of the checker pattern, the lattice spacing, etc.) can be arbitrarily changed. ing. That is,
As an actual device, one type of regular pattern 20 is drawn on the peripheral surface of the cylindrical screen 10, but the pattern form can be changed by increasing or decreasing the rotation speed of the screen 10 to change the detection sensitivity. can do.

Further, according to the perspective distortion measuring device having such a configuration, the adjustment of the detection optical system including the light source lamp 22 for illuminating the screen 10 and the line sensor camera 16 can be performed by adjusting the linear portion corresponding to the camera field of view on the screen. It is advantageous that the uniformity of the light source can be easily assured and the adjustment operation can be simplified. FIG. 3 shows another embodiment of the present invention. The apparatus for measuring the perspective distortion shown in FIG. 3 uses a belt-shaped screen 40 instead of the cylindrical screen 10 shown in FIG.
The same or similar members as those of the embodiment shown in FIG. 1 are denoted by the same reference numerals, and the description thereof will be omitted.

A belt-like screen 40 on which the regular pattern 20 is drawn is wound around rollers 42, 42,
A two-dimensional plane portion 40A is formed. Although not shown, a tubular light source lamp is disposed inside the screen 40, and the screen 40 is rotatable by a screen driving mechanism. With this configuration, the line sensor camera 16 receives the transmitted light of the object 12 while rotating the screen 40 in synchronization with the translational movement of the object 12 by the conveyor device 14, so that the two-dimensional image is developed. Images can be captured.

In each of the above embodiments, the case where the line sensor camera 16 is used as the light receiving device has been described as an example. However, the present invention is not limited to this. In the case where it can be equivalently realized with a light source, for example, a two-dimensional developed image may be captured in combination with a point-like light receiving element that moves in the horizontal direction. Alternatively, a sensor having a plurality of lines of pixels in the vertical direction may be used to perform a combining process based on a minute signal difference between the lines.

The flatness and curvature of the surface of the cylindrical (roller) screen 10 shown in FIG. 1 and the belt-like screen 40 shown in FIG. It is necessary to determine that the distortion of the image projected on the plane in the field of view is less than the distortion caused by the distortion (defect) to be detected.

In the above embodiment, the screen 1
The case where the object 12 is conveyed by the conveyor device 14 while fixing the line sensor camera 16 at a predetermined position with 0 and 40 has been described. However, the present invention is not limited to this, and the object 12 and the line sensor camera (light receiving device) 16 and at least one of the screens 10 and 40 are moved, and one of two-dimensional scans forming an image by moving the detection optical system relative to the device under test 12 is equivalent to May be realized.

[0026]

As described above, according to the method and apparatus for measuring perspective distortion according to the present invention, a screen having a regular pattern is formed in an annular shape, and the object to be measured and the inspection optical system are relatively positioned. By moving the screen in synchronization with the movement of moving and changing the inspection position, the screen is rotated to capture images that have been developed two-dimensionally. Therefore, space saving of the device can be achieved.

Further, by adjusting the rotation speed of the screen, the form of the pattern can be substantially changed, and the detection sensitivity can be changed. In particular, a configuration is adopted in which a one-dimensional line sensor camera is used as the imaging means, the one-dimensional line sensor camera and the annular screen are fixed at a predetermined position, and the object to be measured is transported in a direction perpendicular to the axis of the annular screen. Then, the configuration of the transport device is simple, and since the field of view of the camera is on one line, the adjustment is easy, and the uniformity of the light source for illuminating the screen has a linear area. It is easy to implement.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a configuration of an apparatus for measuring perspective distortion according to an embodiment of the present invention.

FIG. 2 is an external perspective view showing an example of an apparatus for measuring perspective distortion.

FIG. 3 is a perspective view showing a configuration of an apparatus for measuring perspective distortion according to another embodiment of the present invention.

FIG. 4 is a perspective view showing the configuration of a conventional perspective distortion measuring device.

[Explanation of symbols]

Reference Signs List 10, 40: Screen 12: Object to be measured 14: Conveyor device (corresponding to detection position moving means) 16: Line sensor camera (corresponding to light receiving device, imaging device) 18: Image processing device 20: Regular pattern 22: Light source lamp

Claims (3)

[Claims] 1. A screen having a predetermined regular pattern is installed behind a light-transmitting object to be measured, and a light receiving device is disposed in front of the object to be measured, and the object is transmitted by the light receiving device. Receiving the transmitted light, and measuring the perspective distortion of the object to be measured based on the obtained light reception data, wherein a cylindrical or belt-shaped annular screen is used as the screen, the object to be measured, the imaging means, and the screen. The inspection position of the object to be measured is changed by moving at least one of them, and the annular screen is rotationally driven in synchronization with the moving speed of the inspection position, and the received light data of a predetermined measurement range of the object to be measured is obtained. A method for measuring perspective distortion, which is obtained sequentially. 2. A cylindrical or belt-shaped annular screen having a predetermined regular pattern, which is installed on the back side of a light-transmitting device to be measured, and a screen driving means for rotating the annular screen in a circumferential direction; An imaging unit arranged on the near side of the object to be measured in opposition to the annular screen and capturing an image of a regular pattern of the annular screen transmitted through the object to be measured; the object to be measured, the imaging unit, and the annular screen An inspection position moving means for changing at least one of the inspection positions of the object to be measured, and a screen drive for rotating the annular screen in synchronization with a moving speed of the inspection position by the inspection position moving means. Control means for controlling the means, and an image processing apparatus for evaluating the transmission distortion of the device under test based on the image data captured by the image capturing means. An apparatus for measuring perspective distortion, characterized in that: 3. A one-dimensional line sensor camera is used as said imaging means, said one-dimensional line sensor camera and said annular screen are fixed at a predetermined position, and an object to be measured is moved along an axis of said annular screen as inspection position moving means. 3. The apparatus for measuring perspective distortion according to claim 2, wherein a transport device that transports in a direction perpendicular to the direction is used.