JPH1070677A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce moire without deteriorating the image quality by moving an optical path of an incident light from an object continuously in parallel within a range of a movement amount of a length below a pitch between image pickup elements and leading the light to the image pickup element within an exposure time. SOLUTION: An optical path moving means is provided on an optical path between an object 1 and a CCD camera 3, and an incident light A from the object 1 is led to a light receiving face 4 while moving the optical path in parallel by a very small amount within the exposure time. The optical path moving means is made up of a flat transparent glass disk 5 placed on the optical path, a motor 7 driving the flat transparent glass disc 5 around a rotary shaft 11 in parallel with an optical axis 10 of an optical system 2, a tilt means 6 fitted to the rotary shaft 11 so as to tilt a normal of the flat transparent glass disk 5 at a tilt angle θ with respect to the optical axis 11, and a motor drive speed controller 8 driving the motor 7. Furthermore, in this case, the parallel movement amount of the image within the exposure time is preferably selected to be a pitch R1 between the image pickup elements 9 or below.

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 having a large number of two-dimensionally arranged image pickup elements such as CCDs at a constant pitch and for picking up an image of a subject having a repeated picture element pattern.

[0002]

2. Description of the Related Art In recent years, display devices and the like having a fine repetitive picture element pattern, such as CRTs and LCDs, have become more and more fine. Imaged by an imaging device having a large number of imaging elements, image processed,
Defects such as defects have come to be detected.

However, a subject such as a CRT has a fine repetitive picture element pattern. Therefore, when the repetition pitch of the repetition picture element pattern of the subject on the light receiving surface of the image pickup device and the pitch of the image pickup device of the image pickup device come close to each other. The two interfere with each other to generate a striped abnormal image called moiré in the captured image, making it impossible to perform a correct inspection.

Therefore, a conventional imaging apparatus is a two-dimensional CCD camera 1 having an optical system 12 as shown in FIGS.
A birefringent plate 14 having a predetermined thickness is disposed in front of the third light receiving unit 15 as moiré removing means.

A method of removing moire in a conventional image pickup apparatus will be described with reference to the drawings. As shown in FIG. 5, the incident light A from the subject 1 (CRT surface) is refracted on the front surface 16 of the birefringent plate 14 into two light beams, an ordinary light beam B and an extraordinary light beam C, and refracted on the rear surface 17. The light beams travel away from each other by a distance f in a certain direction according to the crystal direction of the birefringent plate 14 and reach the light receiving unit 15. The distance f is one of the pitches R1 between the imaging devices (CCD devices) 9 constituting the light receiving unit 15.
/ 2. That is, as shown in FIG. 6, the moire caused by the ordinary ray B and the image sensor 9 and the moire caused by the extraordinary ray C and the image sensor 9 have the same direction and cycle, and are 互 い に of the cycle. In other words, they are offset by a half wavelength, and are offset.

[0006]

However, in the above-mentioned conventional example, the intensity of the ordinary ray B and the extraordinary ray C are not equal, so that a moiré of a not-ignorable degree remains in the captured image. Further, since the birefringent plate 14 as described above is optically inferior in terms of transmittance, processing accuracy and the like, it also causes deterioration in image quality such as image resolution regardless of the presence or absence of moiré.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide an image pickup apparatus capable of optically reducing moire without deteriorating image quality.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has an image pickup apparatus which has a large number of image pickup elements arranged two-dimensionally at a constant pitch and picks up an object having a repeated picture element pattern. An optical path moving means for guiding an optical path of incident light from a subject to an image sensor while continuously translating the optical path within a range of a predetermined amount within an exposure time, wherein the predetermined amount of movement is a pitch between the image sensors; The length is as follows.

According to the present invention, the positions of the moire peaks generated at a certain point in time continuously move within the exposure time, so that the intensity of the moire peaks is averaged and weakened in the image. Therefore, moire can be reduced. Further, since the amount of parallel movement of the image within the exposure time is equal to or less than the pitch between the imaging elements, the resolution of the image hardly decreases.

If the amount of parallel movement of the image within the exposure time exceeds the pitch length between the image pickup devices, the amount of parallel movement of the image within the exposure time exceeds the resolution of the imaging device, and the resolution of the image decreases. Not preferred.

In the present invention, the optical path moving means includes a flat plate having a normal inclined at a predetermined angle with respect to the optical axis of the incident light, and rotating the flat plate about an axis parallel to the optical axis. When the image forming apparatus is configured to include a rotating unit for rotating the image, the image on the light receiving surface continuously translates on a constant circumference, so that moire generated in any direction can be reduced. Also, since the optical path moving means disposed on the optical path is a flat transparent body, the optical performance hardly decreases. Furthermore,
When no moiré is generated, by stopping the rotation of the flat transparent body, it is possible to take an image without deteriorating the image quality at all, and in the preferred embodiment of the present invention, the flat transparent body can be obtained within the exposure time of the imaging apparatus. Is rotated more than once, the moire pattern, which changes continuously and periodically, is moved one or more times within the exposure time, so that the moire peak intensity is more averaged in the image. The moiré can be further reduced because it is weakened.

In the present invention, when the inclination angle θ is D, the thickness of the transparent plate is N, the refractive index of the transparent plate is N1, the refractive index of the space on the optical path is N2, and the pitch between the imaging elements is R1. , The following relationship, R1 / 2/2 = D.times. (Tan .theta.-tan
(Sin ⁻¹ (N 2 / N 1 × sin θ)) × cos θ, the image on the light receiving surface continuously translates on a circle having a diameter equal to the pitch R 1 between the imaging elements. Even for moire generated in the direction, the intensity of the moire peak is completely averaged in the image,
Moiré can be completely removed.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings.

As shown in FIG. 1 and FIG. 2, one embodiment of the present invention includes an image pickup device (CCD device) 9 and an optical system 2 which are two-dimensionally arranged at a pitch R 1 on the light receiving surface 4. A CCD camera 3 for picking up an image of a subject (CRT surface) 1, and an incident light A from the subject 1 provided on an optical path between the subject 1 and the CCD camera 3 while being translated by a small amount within the exposure time of the CCD camera 3. Light path moving means for guiding to the light receiving surface 4.

The optical path moving means includes a disk-shaped transparent glass plate 5 disposed on the optical path, and a transparent glass plate 5 disposed at a position not to interrupt the optical path and parallel to the optical axis 10 of the optical system 2. A motor 7 for rotating around a rotating shaft 11, a tilting means 6 for tilting a normal line of the transparent glass plate 5 at an inclination angle θ with respect to the optical axis 10 and attaching to the rotating shaft 11, and a motor 7.
And a motor rotation speed controller 8 for driving the motor.

The position shift amount of the transmitted light E of the incident light A from the subject 1 by the flat transparent glass 5 is defined as d, and the position shift amount d is inclined so as to be の of the pitch R 1 between the image pickup devices 9. The angle θ is determined. That is, d = D ×
(Tan θ-tan (sin ⁻¹ (N2 / N1 × sin
θ))) × cos θ, the thickness of the transparent glass plate 5 is D, and the refractive index of the transparent glass plate 5 is N
1, when the refractive index of the space on the optical path is N2, the following relation is obtained: R1 / 2/2 = D × (tan θ−tan (sin ⁻¹ (N2 //
N1 × sin θ))) × cos θ, the inclination angle θ is determined.

Further, the rotation speed of the motor 7 is determined so that the flat glass plate 5 makes one rotation during the exposure time of the imaging apparatus.

According to the configuration of the present embodiment, the image of the subject 1 is translated by one rotation on the circumference of the radius of the positional deviation amount d (that is, the diameter is the pitch R1 between the imaging elements 9) at the same speed during the exposure time. I do.

Therefore, in the case where the repetition pitch of the repetitive picture element pattern of the subject 1 shown on the light receiving surface 4 approaches the pitch R1 between the image pickup devices 9 and moire occurs in the image, the action of the optical path moving means causes As shown in FIG. 3, the peak of the moire generated at a certain point in time corresponds to the exposure time T.
At 1, since it moves between one pitch of the moire,
The combined moiré in the imaged screen disappears after being completely averaged in the screen. Further, since the image of the subject 1 makes one revolution on the circumference having the pitch R1 as the diameter, the above-described effect can be obtained regardless of the direction of the moire stripe pattern.

The amount of parallel movement of the image within the exposure time is preferably equal to or less than the pitch R1 between the image pickup devices 9, and particularly preferably the pitch R1, but if it exceeds the pitch R1, the amount of parallel movement of the image within the exposure time is reduced. Since the resolution exceeds the resolution of the imaging device, the resolution of the image is undesirably reduced.

The number of rotations of the transparent glass plate 5 during the exposure time of the image pickup device is preferably one or more, particularly preferably an integer. If the number of rotations is less than one rotation, averaging of the moire peak strength in the image may not be perfect.

In the above embodiment, when no moiré is generated, the rotation of the transparent glass plate 5 is stopped so that an image can be taken without any deterioration in image quality.

[0023]

According to the present invention, the position of the moire peak occurring at a certain point in time continuously moves within the exposure time, and the intensity of the moire peak is averaged in the image. Because it is weakened, moire can be reduced. Further, since the amount of parallel movement of the image within the exposure time is equal to or less than the pitch between the imaging elements, the resolution of the image hardly decreases. Therefore, moire can be optically reduced without lowering image quality.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is a diagram illustrating moire before and after combination according to an embodiment of the present invention.

FIG. 4 is a schematic view showing a conventional example.

FIG. 5 is a partially enlarged cross-sectional view illustrating moiré removing means in a conventional example.

FIG. 6 is a diagram illustrating moire before and after combination in a conventional example.

[Brief description of reference numerals]

 DESCRIPTION OF SYMBOLS 1 Subject (CRT) 5 Flat transparent glass 6 Inclination means 7 Motor 8 Motor rotation speed controller 9 Image sensor 10 Optical axis 11 Rotation axis A Incident light D Plate thickness of flat transparent glass θ Tilt angle N1 Refractive index of flat transparent glass N2 light Refractive index of space on road R1 Pitch between image sensors

Claims (4)

[Claims] 1. An image pickup apparatus having a large number of image pickup devices arranged two-dimensionally at a constant pitch and picking up an image of a subject having a repetitive picture element pattern, wherein an optical path of incident light from the subject is determined within an exposure time. An image pickup apparatus, comprising: an optical path moving unit that guides the image pickup device while continuously performing parallel movement within a range of the movement amount, wherein the predetermined movement amount is equal to or less than a pitch between the image pickup devices. 2. An optical path moving means comprising: a flat plate transparent body whose normal is inclined at a predetermined angle with respect to an optical axis of incident light; and a rotation for rotating the flat plate transparent body about an axis parallel to the optical axis. The imaging device according to claim 1, further comprising: 3. The apparatus according to claim 1, wherein the flat transparent body is within one exposure time of the imaging device.
The imaging device according to claim 2, wherein the imaging device is rotated by at least rotation. 4. The inclination angle θ is D, the thickness of the transparent plate is D,
The refractive index of the transparent plate is N1 and the refractive index of the space on the optical path is N1.
2. When the pitch between the imaging elements is R1, the following relationship is obtained: R1 / 2/2 = D × (tan θ−tan (sin ⁻¹ (N2 //
The imaging device according to claim 2, wherein the following condition is satisfied: N 1 × sin θ))) × cos θ.