JPH10173967A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize picture element shift by parallel flat plates and escape of the parallel flat plates with a simple configuration. SOLUTION: A support frame 16 supports parallel flat plates 14 turnably around a shaft 18. A slider 20 having the shaft 18 is fed horizontally by a feed screw 22b turned by a drive source 22a of a feeding mechanism 22. The slider 20 holds an optical member 26. A step cam 28a is formed to a side of a board 28 opposed to the support frame 16 and a cam follower 16a following to the step cam 28a while being in press contact therewith is formed to the support frame 16 on the other hand. The cam follower 16a follows a cam face of the step cam 28a in response to the movement of the slider 20. Thus, the parallel flat plates 14 are tilted by a prescribed angle. When the slider 20 moves up to one end, the parallel flat plates 14 are deviated from an image pickup optical flux and an optical member 26 enters the image pickup optical flux.

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 capable of shifting and photographing pixels.

[0002]

2. Description of the Related Art A solid-state image sensor using silicon, such as a CCD image sensor generally used in a video camera, generally has sensitivity not only in a visible light region but also in an infrared region. In an imaging device such as an electronic still camera using a solid-state imaging device having sensitivity also in the infrared region, image deterioration such as a decrease in contrast of a captured image or a blurred captured image due to infrared light occurs. There was something. In order to prevent such image deterioration, a configuration has been proposed in which an infrared cut filter that blocks infrared light incident on an image sensor is provided in a shooting optical path.

In order to suppress the occurrence of false colors in a color solid-state image pickup device, a configuration having an optical low-pass filter in a photographing optical path has been proposed. An optical low-pass filter is not necessary when an image without color information is generated from a color image sensor, and in such a case, a configuration has been proposed in which the optical low-pass filter is retracted outside the imaging optical path.

[0004] In order to reduce the cost and size of an image pickup apparatus, there is known an automatic focus adjustment apparatus that generates an AF signal from an output of a solid-state image pickup device and performs focus adjustment. In a situation where the surroundings are dark, an AF that is so large that the noise of the image sensor can be ignored.
In order to obtain a signal, a configuration is also known in which the photoelectric conversion time of the image sensor, that is, the charge accumulation time is set to be long. However, if the charge accumulation time is set to be long, an image is affected by camera shake or subject shake. As a result, the automatic focus adjustment based on the output of the image sensor may not function effectively. For this purpose, illumination may be used in combination, as in the case of a silver halide film camera.

In order to increase the resolution of the image sensor and suppress the generation of false colors, the imaging surface of the image sensor is moved by a predetermined amount relative to the photographing optical axis on a plane perpendicular to the photographing optical axis. There is a so-called pixel shift photographing method for complementing between pixels of an image sensor. For example, a parallel plate made of glass or the like is arranged in front of the image sensor at a predetermined angle with respect to the photographing optical axis to shift the incident light beam in a direction perpendicular to the photographing optical axis, so that the photographing light can There has been proposed a configuration that achieves the same effect as when a predetermined amount is moved on a plane perpendicular to the axis. With this configuration, it is possible to realize pixel shift shooting with a small circuit configuration and at low cost.

By using the above-mentioned infrared cut filter as a parallel flat plate for pixel shift photographing, the infrared cut filter has both an effect of blocking infrared light to prevent image deterioration and an effect of increasing resolution by pixel shift photographing. Can be obtained at the same time.

[0007]

Some of the illuminating means for assisting the automatic focusing are illuminated with infrared light so that the subject is not dazzled by the illumination. In addition, even in the illumination means of visible light, the light generally includes infrared light,
When the image pickup device receives not only the visible light component of the illumination light but also the infrared light component, the power consumption of the illumination means in generating the AF signal can be reduced.

However, as described above, an infrared cut filter is provided on the front surface of the solid-state image pickup device, and only visible light of the illumination light by the illumination means can be used. Therefore, the illumination is performed with a sufficient amount of light to generate an AF signal. Attempting to do so requires a lot of power, and as a result, there has been a problem that the person who is the subject is dazzled.

In order to solve this, a mechanism for retracting the infrared cut filter out of the photographing optical path during illumination may be provided. However, in an image pickup apparatus using a pixel shift photographing method in which an incident light beam is displaced by tilting a parallel plate of an infrared cut filter, it has been difficult to realize a compact mechanism for retracting the infrared cut filter out of the photographing optical path.

Further, in an image pickup apparatus provided with an optical low-pass filter, since the image pickup section becomes large, it is desired that the tilting mechanism of the parallel plate and the insertion / removal mechanism of the infrared cut filter or the optical low-pass filter be made compact. Was.

According to the present invention, there is provided an image pickup apparatus having a pixel shifting method in which an incident light beam is shifted by tilting a parallel plate, and a retracting mechanism for retracting the parallel plate from an image pickup optical path in order to effectively use illumination light from an illumination means. It is intended to be presented.

Another object of the present invention is to provide an image pickup apparatus having a simple mechanism for realizing a parallel plate tilting operation for retreating a parallel plate from an image pickup optical path and shifting pixels.

[0013]

According to the present invention, there is provided an image pickup apparatus comprising: a parallel plate movable between a first position within a photographic light beam and a second position outside the photographic light beam; And a tilting means for tilting a predetermined angle within the photographic light beam. Thereby, the parallel plate can be retracted from the image pickup optical path and the tilting operation of the parallel plate for shifting the pixels can be realized.

The tilting means has a holding frame for holding the parallel plate, and a moving member for moving the holding frame from the first position to the second position, and the tilting means is used for moving the moving member. By tilting the holding frame accordingly,
With two driving sources, the parallel plate can be retracted from the imaging optical path and the tilting operation of the parallel plate for shifting the pixels can be realized.

A cam having a plurality of heights with respect to the imaging surface, and a contact portion provided on the holding frame and in contact with the cam surface can accurately form a parallel flat plate with a simple structure.
Can be tilted at the desired angle.

By using a parallel plate as an infrared cut filter, deterioration of an image due to infrared rays can be reduced, and by using a low-pass filter, generation of false colors can be prevented.

When the parallel plate is at the second position, another optical function can be provided by providing an optical member located in the photographic light beam. By making the optical path length in the thickness direction of the optical member substantially the same as that of the parallel plate,
When the optical member is used, it is possible to prevent the focal plane from shifting in the optical axis direction. Further, even if the focal plane is displaced in the optical axis direction due to a manufacturing error of the photographing optical system or the like, the correction amount can be small, and the burden on the focus adjusting optical system can be reduced.

[0018]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 1 is a front view of an image pickup section according to an embodiment of the present invention. That is, FIG. 1 is a diagram in which the imaging unit is viewed from the subject side in the optical axis direction.

In FIG. 1, reference numeral 10 denotes an image pickup surface of a solid-state image pickup device such as a CCD image pickup device or an image pickup tube, on which an object is imaged by a photographing optical system (not shown). Also, the output signal of the image sensor (or image tube)
After predetermined signal processing, it is also used as an AF signal. 1
Reference numeral 2 denotes an area where a photographic light beam from a photographic optical system (not shown) is incident.

Reference numeral 14 denotes a parallel flat plate disposed in front of the image pickup surface 10. In this embodiment, an infrared cut filter is formed on one surface of an optical member such as glass or plastic that transmits light. Of course, the parallel plate 14
Instead of an infrared cut filter, an optical low-pass filter may be used, or an optical member having no filter function may be used. The parallel plate generally has the effect of shifting the light beam laterally according to the angle of incidence of the light beam, and in this embodiment,
By tilting the parallel plate 14 with respect to the optical axis, the imaging optical axis is shifted in a direction perpendicular to the imaging optical axis, and pixel shift imaging is performed. The mechanism for tilting the parallel plate 14 will be described later.

Reference numeral 16 denotes a holding frame which holds the parallel flat plate 14 so as to be rotatable about a shaft 18 as a center of rotation. Holding frame 16
The image pickup surface 10 is provided by an urging means (not shown) such as a spring.
Are biased in the direction approaching.

Reference numeral 20 denotes a slider which holds the shaft 18 and is movable along a feed screw 22b which is rotated by a drive source 22a of a feed mechanism 22. The slider 20 is used to insert the parallel plate 14 into the area 12 and to retreat from the area 12. used. The feed mechanism 22 for moving the slider 20 includes a drive source 22a such as a step motor, a feed screw 22b rotated by the drive source 22a, and a bearing 22c that supports the tip of the feed screw 22b. At the upper end of the slider 20, a nut 20a engaging with the feed screw 22b is formed, and at the lower end of the slider 20, two fitting portions 20 fitted to a shaft 24 installed in parallel with the feed screw 22b.
b, 20c are formed. Shaft 24 and fitting part 20
The sliders 20 and 20c allow the slider 20 to move only in a plane parallel to the plane of FIG. The forward / reverse rotation of the drive source 22a causes the slider 20 to move left and right in FIG.

Reference numeral 26 denotes an optical member that is held by the slider 20 and moves at least with the area 12 by moving with the slider 20. The optical member 26 may be a lens that changes the focal length of the photographing optical system, or may be an optical filter such as an ND filter. In the present embodiment, the parallel plate 14 has substantially the same optical path length in the thickness direction as the parallel plate 14 and has no infrared cut filter function.

A substrate 28 holds the shaft 24.

FIG. 2 is a plan view of the parallel plate 14 in the middle of retreating from the region 12, and FIG. 3 is a plan view of the parallel plate 14 completely retreating from the region 12. In the state shown in FIG. 3, the optical member 26 is completely inserted into the region 12, and imaging using the optical characteristics of the optical unit 26 becomes possible.

In the present embodiment, by inserting the optical member 26 having no infrared cut filter function into the region 12, the infrared light of the illumination light is also incident on the image pickup device or the image pickup tube, and an AF signal of sufficient intensity is obtained. be able to. That is, the illumination light of the subject by the illumination means (not shown) such as an LED having an infrared component can be used effectively, and the illumination means can be reduced in size, power consumption can be reduced, and the illumination range can be expanded. As described above, in the present embodiment, the infrared cut filter function can be temporarily evacuated in a situation where the infrared cut filter function becomes a hindrance to photographing, as compared with an imaging apparatus that always uses the infrared cut filter function. It is possible not only to save power but also to cope with a wider range of shooting conditions.

When the optical member 26 is a lens that changes the focal length of the photographing optical system, variable magnification photographing in which at least two focal lengths can be selected becomes possible. Shooting with the aperture opened or with a reduced shutter speed becomes possible.

As in the present embodiment, the optical member 26 is a parallel flat plate having an infrared cut filter function having substantially the same optical path length in the thickness direction as the parallel flat plate 14, so that the parallel flat plate 14 can be substituted for the region 12. Even when the optical member 26 is inserted, the optical path length between the imaging surface 10 and the photographing optical system (not shown) does not change so much. As a result, even when changing from the parallel plate 14 to the optical member 26 or from the optical member 26 to the parallel plate 14, it is not necessary to readjust the focus by driving the focus adjustment lens, and the imaging apparatus can be simplified. However, the parallel plate 1
Needless to say, it is necessary to correct the focus adjustment when the shift of the focal plane due to the difference in the optical path length due to the manufacturing error of the optical member 4 and the optical member 26 cannot be ignored. 26 is a parallel flat plate whose optical path length is substantially the same as that of the parallel flat plate 14, the displacement of the focal plane is reduced by the optical member 2.
6 is extremely small as compared with the case where the lens 6 does not exist, and the amount of correction of the focal plane by driving the focus adjustment lens can be reduced.

Although not shown, by providing an optical member tilting means for tilting the optical member 26 with the movement of the slider 20 when the optical member 26 is in the photographic light beam,
Pixel shift shooting can be realized. For example, instead of fixing the optical member 26 to the slider 20, the parallel plate 14
The cam member (described in detail later), which is a means for tilting the parallel flat plate 14, is supported by a holding member as described above.
This can be realized by providing a separate device. It is not necessary to configure the cam system of the parallel plate 14 and the optical member 26 to have the same shape, and a configuration suitable for the pixel shift photographing performed by each of the parallel plate 14 and the optical member 26 may be used.

Next, with reference to FIG. 4, the principle of pixel shift photographing in this embodiment will be described. FIG. 4 shows the parallel plate 1
FIG. 4 is a diagram observed from a direction perpendicular to the optical axis. Reference numeral 30 denotes a light beam substantially parallel to the optical axis. A, B and C are respectively
The state where the parallel plate 14 is relatively inclined at a predetermined angle is shown. When the parallel plate 14 is tilted as in the state B or the state C, as is well known, an incident light beam is shifted laterally like a light beam B ′ or a light beam C ′ due to a difference in the refractive index between the parallel plate 14 and air, as is well known. Reach

FIGS. 5 and 6 are enlarged views of a portion D on the imaging surface 10. FIG. 5 shows three colors of red (R), green (G), and blue (B) on the imaging surface 10 in this order. FIG. 6 shows a case where two color filters are arranged in the order of cyan (Cy) and magenta (M) on the imaging surface 10. In the case of FIG. 5, the parallel plate 14 is tilted so that the light beam is shifted to the next pixel and the next pixel, and each time, the image is taken and the obtained three images are combined to obtain an image without false color. Can be. In the case of FIG. 6, the parallel plate 14 is tilted so that the light beam is shifted between the cyan and magenta color filters, and each time the image is taken and the obtained two images are combined to improve the resolution. Can be obtained.

By performing pixel shift photographing in this manner,
It is possible to improve the resolution of an image and suppress the generation of false colors. Note that the method of shifting light rays described in this embodiment is an example, and the present invention is not limited to the method described here.

The mechanism and operation of tilting the parallel plate 14 to the positions B and C in FIG. 4 will be described with reference to FIGS. FIG.
10 are cross-sectional views taken along line AA in FIG. A step cam 28a is formed on the surface of the substrate 28 facing the holding frame 16, while a cam follower 16a is formed on the holding frame 16 so as to contact and follow the step cam 28a. The cam follower 16a is formed with a step cam 28a by a spring (not shown) or the like.
8 In this embodiment, the step cam 28a
Has three cam surfaces 28b, 28c, 28d. Needless to say, the cam surfaces 28b, 28c,
28d is an example, and the present invention is not limited to this number and shape.

FIG. 7 shows that the cam follower 16a is
b, in which state the slider 20
Is located at the same position as in FIG. 1, and the surface of the parallel plate 14 is perpendicular to the optical axis during photographing. When the slider 20 is moved from the state shown in FIG. 7 to the position shown in FIG. 8, ie, the cam follower 16a contacts the cam surface 28c, the parallel plate 1
4 tilts by a predetermined angle. Further, as shown in FIG. 9, the slider 2 is moved until the cam follower 16a comes into contact with the cam surface 28d.
When 0 is moved, the parallel flat plate 14 is tilted to the pixel shift shooting angle.

The slider 20 is located at the position shown in FIG. 8 or FIG.
Even when there is, the parallel plate 14 is made sufficiently wide so that it does not deviate from the region 12 in FIG. 1 and the image is not blurred.

In the present invention, the direction of inclination of the parallel plate 14 is not limited to one. For example, a second holding frame capable of rotating the parallel flat plate 14 around a rotation axis that is not parallel to the rotation axis of the holding frame 16 is provided inside the holding frame 16, and the slider 20 moves while being in contact with the second holding frame. By providing the second cam for tilting the second holding frame to the substrate 28 in accordance with the above, the tilting direction of the parallel flat plate 14 can be made two. By doing so, the shifting direction of the light beam in the pixel shifting shooting can be extended two-dimensionally, and more various pixel shifting effects can be obtained. Similarly, the optical member 26 can be inclined in two directions. .

FIG. 10 shows a state where the slider 20 is further moved to the left in the figure, the parallel plate 14 is retracted from the area 12, and the optical member 26 is inserted instead. As described above, in the present embodiment, by controlling the movement of the slider 20, it is possible to select between the pixel shift shooting and the shooting using the infrared cut filter.

Although the imaging device using the optical member 26 has been described, the optical member 26 may not be provided. In this case, it is impossible to perform photographing utilizing the characteristics of the optical member 26, but the imaging unit can be downsized. When the parallel plate 14 retreats from the area 12, the lens position is corrected by an amount corresponding to a change in the optical path length between the imaging surface 10 and an unillustrated photographing optical system.

[0040]

As can be easily understood from the above description, according to the present invention, it is possible to freely select a pixel shift photographing using a parallel plate and a photographing that does not require a parallel plate, and it is very simple. It can be realized with a simple configuration.

By forming an infrared cut filter on a parallel plate, deterioration of an image due to infrared rays can be prevented in both normal shooting and pixel shift shooting.

By forming an optical low-pass filter on a parallel plate, it is possible to prevent the occurrence of false colors in both normal shooting and pixel shift shooting.

A plurality of optical effects can be obtained by inserting another optical member (for example, an ND filter) into the photographing light beam while the parallel plate is completely retracted out of the photographing light beam. it can. Since another optical member also protects the imaging surface, it is possible to prevent dust from adhering to the imaging surface.

By making the optical path lengths of the parallel plate and another optical member substantially the same, it is possible to prevent the focal plane from shifting in the optical axis direction when another optical member is used. Further, even if the focal plane is displaced in the optical axis direction due to a manufacturing error of the photographing optical system or the like, the correction amount can be small, and the burden on the focus adjusting optical system can be reduced.

[Brief description of the drawings]

FIG. 1 is a front view of a main part of an embodiment of the present invention.

FIG. 2 is a front view of the slider 20 during movement.

FIG. 3 is a front view of a state where the movement of the slider 20 is completed.

FIG. 4 is a diagram for explaining the principle of pixel shift photographing by tilting the parallel plate 14;

FIG. 5 is an explanatory diagram of how to shift a light beam in pixel shift shooting with respect to an image sensor having an RGB color filter.

FIG. 6 is an explanatory diagram of how to shift a light beam in pixel shift shooting with respect to an image sensor having a complementary color filter.

FIG. 7 is a cross-sectional view showing a state where the cam follower 16a is in contact with a cam surface 28b.

FIG. 8 is a cross-sectional view of a state in which the cam follower 16a contacts the cam surface 28c.

FIG. 9 is a cross-sectional view illustrating a state where the cam follower 16a contacts the cam surface 28d.

FIG. 10 is a cross-sectional view showing a state in which the parallel plate is retracted from the area and the slider is moved to a position where the optical member is inserted instead.

[Explanation of symbols]

 10: imaging surface 12: area where a photographing light beam is incident 14: parallel plate 16: holding frame 16a: cam follower 18: shaft 20: slider 20a: nut 20b, 20c: fitting portion 22: feed mechanism 22a: drive source 22b: feed Screw 22c: Bearing 24: Shaft 26: Optical member 28: Substrate 28a: Step cam 28b, 28c, 28d: Cam surface 30: Light beam substantially parallel to the optical axis

Claims (8)

[Claims] 1. A parallel flat plate movable between a first position in a photographic light beam and a second position outside the photographic light beam, and a tilt of the parallel flat plate in the photographic light beam by a predetermined angle. And an imaging device. 2. The tilting means has a holding frame for holding the parallel flat plate, and a moving member for moving the holding frame from a first position to a second position, and the tilting means includes a moving member. The imaging device according to claim 1, wherein the holding frame is tilted according to the movement of the image. 3. The tilting means further includes a cam having a plurality of heights with respect to the imaging surface, and a contact portion provided on the holding frame and in contact with the cam surface. The imaging device according to claim 1, wherein the contact portion moves while contacting the cam surface with movement of the member. 4. The imaging device according to claim 1, wherein the parallel plate is an infrared cut filter. 5. The imaging device according to claim 1, wherein the parallel plate is an optical low-pass filter. 6. The image pickup apparatus according to claim 1, further comprising an optical member positioned in the photographing light beam when the parallel plate is at the second position. 7. The imaging device according to claim 6, wherein the optical member has substantially the same optical path length in the thickness direction as the parallel plate. 8. The imaging apparatus according to claim 1, further comprising an optical member tilting unit that tilts the optical member by a predetermined amount when the optical member is in the photographing light beam.