JPH09172568A - Image pickup device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To capture image information with high resolution at a high speed by means of so-called picture element shift by driving switchingly optical transmission plates so that each of plural optical transmission planes is arranged to an optical path of a light passing through a lens group. SOLUTION: The device is provided with parallel flat plate glass groups 4a-4d and a support frame 12 or the like to support the parallel flat plate glass groups 4a-4d. Then a pinion 17 engaged with an output shaft 16 of a stepping motor 5 for driving the parallel flat plate glass groups 4a-4d meshes with a gear 12a of the support frame 12 and the support frame 12 is driven by the driven of the stepping motor 5. Then the parallel flat plate glass groups 4a-4d are switchingly driven so that each of plural optical transmission plates of the parallel flat plate glass groups 4a-4d arranged at a prescribed angle tilted to an optical axis major plane of a lens group on an optical path of light passing through the lens group in arranged on the optical path of light passing through the lens group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image pickup device, and more particularly to an image pickup device suitable for use in an image input device for a computer capable of obtaining high resolution image information by performing so-called pixel shift using parallel plate glass. Regarding the device.

[0002]

2. Description of the Related Art In recent years, a video camera has been widely used as an image input device for a computer. In particular, a system combining a video camera and a computer (for example, a personal computer or a workstation) is a D system.
It is being used for TP (desktop electronic / editing printing system), image e-mail, and video conferencing system.

Among such systems, in recent years, a high resolution image pickup device such as a video camera has been developed especially in consideration of HDTV (High Definition Television). It has become possible to edit characters and images using a system including a device, and to exchange information with a high-quality image obtained by such a high-resolution imaging device.

[0004]

However, most of current video cameras have an image pickup device having a pixel number of about 250,000 to 400,000 pixels (some have 580,000 pixels). It is difficult to obtain high-quality images and HDT
It cannot correspond to V. In addition, although a video camera that can obtain high-resolution image information has been partially commercialized for a special purpose, the image sensor is very expensive, so that it is widely used as a general consumer device. It is a big obstacle.

However, in recent years, an image pickup device having a relatively small number of pixels of about 400,000 pixels is used, a part of the lens system is displaced, and the optical path of light passing through the lens system is shifted to form an image pickup device. A system for increasing the resolution of image information by increasing the amount of incident optical image information has been commercialized, and with such a technology, the price reduction of a video camera compatible with HDTV is in progress.

The above-described technique is a so-called pixel shift using parallel flat plate glass to achieve high resolution, and the outline thereof will be described below with reference to FIG.

FIG. 12 is a plan view showing a schematic structure of an optical system of a conventional image pickup device which shifts pixels by using a parallel plate glass. In the figure, 201 is a lens group for guiding an optical image from a subject to an image sensor 202, 202 is an image sensor for converting an optical image into an electric signal, and 203 is a rotation fulcrum at both ends in the horizontal direction. A first parallel plate glass holding frame provided with moving shafts 205 and 206;
Is a first parallel plate glass fixed to the central portion of the first parallel plate glass holding frame 203.

The first parallel plate glass 204 is a first parallel plate glass holding frame 20 driven by a drive source (not shown).
The lens group 2 is rotated as the lens 3 is rotationally driven about the rotary shafts 205 and 206 (in the direction of arrow a in the figure).
The optical path of the light beam incident on the image sensor 202 via 01 can be vertically shifted.

Reference numeral 207 designates a second parallel flat plate glass holding frame 207 having rotary shafts 209 and 210 serving as rotary fulcrums at both ends in the vertical direction, and 208 fixed to the central portion of the second parallel flat plate glass holding frame 207. It is the second parallel flat plate glass.

The second parallel flat plate glass 208 is the second parallel flat plate glass holding frame 20 by a driving source (not shown).
The lens group 2 rotates as the lens 7 is driven to rotate about the rotating shafts 209 and 210 (in the direction of arrow b in the figure).
The optical path of the light beam incident on the image sensor 202 via 01 can be horizontally shifted.

Reference numeral 211 denotes an optical low-pass filter that changes the frequency characteristic of optical image information by utilizing the birefringence of quartz, and such an optical low-pass filter is generally composed of at least two quartz plates. One is horizontal,
The other one is arranged in front of the image sensor 202 so as to change the frequency characteristic in the vertical direction. Further, the separation width of the ordinary ray and the extraordinary ray due to the birefringence is appropriately set according to the number of pixels of the image pickup element 202, the pixel arrangement, the signal processing circuit, and the like.

Next, the principle of shifting the optical path by the parallel plate glass will be described with reference to FIG. FIG. 4A is a diagram showing a state in which the parallel flat glass plates 204 and 208 are positioned in parallel (in the same plane) with the optical axis main plane of the light passing through the lens group, and FIG. It is a figure which shows the state which the angle (theta) displaced clockwise from the state of FIG.

In FIG. 1 (a), a parallel plate glass 20
The thickness of 4,208 in the optical axis direction is d, and the parallel flat glass 20 is
The refractive index of 4,208 is N, and the light ray m is parallel flat glass 20.
The incident angle (angle formed by the incident light m and the surface normal) when entering the parallel flat glass 204, 208 is Φ1, and the light ray m incident inside the parallel flat glass 204, 208 and the surface normal of the parallel flat glass 204, 208. If the angle formed by is Φ'1, the parallel plate glass 20
The deviation amount δ1 of the optical path of the light ray m passing through 4,208 is expressed by the following equation. δ1 = {1- (1 / N) · (COSΦ1 / COSΦ′1)} · d · SINΦ1 (1) Here, when the incident angle Φ1 is very small, CO
Since SΦ1≈Φ′1 and SINΦ1≈Φ1 are established, the above formula (1) can be expressed by a simple approximate formula such as the following formula. δ1 = (1-1 / N) · d · Φ1 (2) Further, in the same figure (b), as in the case of the figure (a), the thickness in the optical axis direction of the parallel flat glass 204, 208 is d, The refractive index of the parallel plate glasses 204 and 208 is N, the incident angle (angle between the incident light m and the surface normal) when the light ray m enters the parallel plate glasses 204 and 208 is Φ2, and the parallel plate glass 20.
4, 208, and the parallel plate glass 20
If the angle formed by the surface normals of 4, 208 is Φ′2, the deviation amount δ2 of the optical path of the light ray m that has passed through the parallel flat glass plates 204, 208 is expressed by the following equation. δ2 = (1-1 / N) · d · Φ2 (3) Here, since Φ2 = Φ1 + θ, the parallel flat glass 204, 208 changes from the state of FIG. 13 (a) to the state of FIG. 13 (b). The optical path change amount δs when the angle θ is displaced is as follows: δs = δ2-δ1 = (1-1 / N) · d · Φ2- (1-1 / N) · d · Φ1 = (1-1 / N) · d · (Φ2-Φ1) = (1-1 / N) · d · θ (4)

Next, an example of the pixel array and aperture of the image pickup element 202 will be briefly described with reference to FIG. FIG. 14 (a)
In, the arrow H indicates the horizontal scanning direction, and the arrow V indicates the vertical scanning direction. A yellow color filter Y and a magenta color filter M are alternately arranged at a pixel interval ph on one of two pixel lines adjacent to each other in the direction of the arrow V, and a cyan color filter C and a green color filter G are arranged on the other one. Similarly, they are alternately arranged at pixel intervals ph. In addition, a yellow color filter Y and a cyan color filter C are provided on one of two pixel lines adjacent to each other in the direction of the arrow H so that the pixel spacing pv
Are alternately arranged and the other side is magenta color filter M
Similarly, the green filters G are alternately arranged at the pixel interval pv.

Image sensor 20 having such a pixel array
2, the state shown in FIG. 13 (a) is changed to the state shown in FIG. 13 (b).
By displacing the parallel flat glass by an angle θ in the state shown in,
The deviation amount of the optical path is, for example, 1/2 pixel, that is, (1 /
2) .ph and (1/2) .pv, if the thickness d of the parallel flat plate glasses 204 and 208 is set as shown in FIG.
As shown in (b), it is possible to obtain an image information amount that is 16 times the normal amount by a matrix of 4 times in the horizontal direction and 4 times in the vertical direction.
It is possible to achieve high resolution of image information by using an image sensor having a relatively small number of pixels.

Next, another conventional example of a parallel plate glass driving unit for shifting pixels will be described with reference to FIG. In the configuration of the parallel plate glass driving unit described with reference to FIG. 12, the parallel plate glass driving unit for performing horizontal pixel shifting and the driving unit for performing vertical pixel shifting are completely separated from each other. This is a simple configuration in which the parallel plate glass is independently driven by each drive unit.

However, in the above-mentioned conventional parallel plate glass driving section, since the thickness in the optical axis direction increases, the lens length becomes long and the distance from the rear end of the lens to the image pickup element (ie, back focus) becomes long. Therefore, it may be difficult to obtain desired optical characteristics.

Further, since it is necessary to separately provide parallel flat glass plates to shift the pixels in the horizontal direction and the vertical direction, the number of parts is increased. Therefore, there is also proposed an image pickup device having a configuration capable of performing pixel shift in the horizontal direction and the vertical direction with a single parallel plate glass.

FIG. 15 is a plan view showing a schematic structure of a parallel plate glass driving section for shifting pixels in a horizontal direction and a vertical direction with one parallel plate glass. In the figure, 232 is a first frame that holds the parallel flat plate glass 231, 233 and 234 are rotary shafts provided at both ends of the first frame 232 in the horizontal direction, and 235 is a lower end of the first frame 232. It is a first cam pin provided. Reference numeral 236 is a first cam (Y cam), and a part of the first cam pin 235 abuts on the cam surface of the first cam 236 so that the first frame 232 rotates about the axis A in the figure as a rotation center. Be moved.

Reference numeral 237 denotes a second frame having a square V shape, and the first frame 2 is provided at both ends in the horizontal direction.
Bearing portions 238 and 239 that are rotationally engaged with the rotating shafts 233 and 234 provided on 32 are provided. 2
Reference numeral 40 is a second cam pin provided at one end of the second frame 237, and 249 is a second cam (X cam). Second
A part of the second cam pin 240 abuts on the cam surface of the cam 249, and the second frame 237 is rotated about the B axis in the drawing as a rotation center.

The rotating shafts 241 and 242 (not shown) provided at both ends in the vertical direction of the second frame 237 are
Bearings 24 provided at both ends of the base 250 in the vertical direction
3 and 244 (not shown), the second frame 237 is held rotatably in the horizontal direction.

Also, the first and second cam pins 235,
240 is constantly in pressure contact with the first and second cams 236 and 249 by springs 245 and 246, respectively. 24
Reference numerals 7 and 248 denote first and second stepping motors for driving the parallel plate glass 231 in the vertical and horizontal directions, respectively, which are fixed to the base 250.

FIG. 16 shows the first or second cam 236,2.
It is the figure which looked at 49 from the front side of the output shaft of the stepping motor. As shown in the figure, each of the cams 236 and 249 has an eccentric structure at a predetermined angle.
Each cam 236, 249 as the 7, 248 rotates
Rotates, the first or second cam pins 235, 240 pressed against the respective cams 236, 249 move, and the parallel flat plate glass 231 is slightly displaced in the horizontal and vertical directions to perform pixel shifting. ing.

However, in the above-mentioned conventional image pickup device which shifts pixels in the horizontal direction and the vertical direction by one parallel plate glass, the rotary motion of the cam is converted into the linear motion to drive the parallel plate glass. Therefore, the reciprocating operation has to be performed in the horizontal and vertical directions depending on the pixel capturing order, and it is very difficult to shorten the image capturing time.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to take in image information at a high speed by a so-called pixel shift method, reduce the number of parts, and perform low-cost imaging. The purpose is to provide a device.

[0026]

In order to achieve the above object, the invention according to claim 1 is an image pickup device for converting optical image information into an electric signal, and a lens for forming an optical image on the image pickup device. Group, and an optical path changing means for displacing an optical path of light passing through the lens group, the optical path changing means having a light transmitting flat plate inclined at a predetermined angle with respect to an optical axis main plane of the lens group. Is at least one light-transmissive flat plate having a plurality of light-transmissive flat surfaces that can be arranged on the optical path of the light passing through the lens group at a predetermined angle with respect to the optical axis principal plane of the lens group; Light transmission plane switching means for switching and driving the transmission flat plate such that each of the plurality of light transmission planes is arranged on the optical path of light passing through the lens group.

According to a second aspect of the present invention, in the image pickup apparatus according to the first aspect, the light transmitting plane switching means has a light transmitting flat plate holding means for holding the at least one light transmitting flat plate. Each of the plurality of light transmitting planes is switched and arranged on the optical path of the light passing through the lens group by rotating the flat plate holding means.

According to a third aspect of the present invention, in the image pickup device according to the first or second aspect, the at least one light transmitting flat plate has a thickness in an optical axis direction at a portion where each of the plurality of light transmitting planes is formed. However, the optical path of the light passing through the lens group is set to be shifted in a desired direction by a desired width.

According to a fourth aspect of the present invention, in the image pickup device according to any one of the first to third aspects, the at least one light transmitting flat plate is integrally formed with the light transmitting flat plate holding means. It is characterized by

According to a fifth aspect of the present invention, in the image pickup apparatus according to any one of the first to fourth aspects, the plurality of light transmitting planes are integrally formed on one light transmitting flat plate. Characterize.

According to a sixth aspect of the present invention, in the image pickup apparatus according to any one of the first to fifth aspects, the lens group limits a spatial frequency of optical image information of light incident on the image pickup element. An optical low-pass filter is provided, and the optical low-pass filter is rotatably held about the photographing optical axis.

According to a seventh aspect of the present invention, in the image pickup apparatus according to any one of the first to sixth aspects, the lens group changes the cutoff frequency characteristic by rotating the optical low pass filter. Is characterized by.

[0033]

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

FIG. 1 is a plan view showing a schematic structure of an image pickup apparatus according to an embodiment of the present invention. In the figure, 1
Is a lens group for guiding an optical image from a subject to the image pickup device 2, 2 is an image pickup device for converting optical image information into an electric signal, and 3 is a parallel plate glass driving unit, which is shown in the main plane of the optical axis. It has a parallel plate glass holding frame that can rotate in the direction of the center a.

Reference numeral 4 is a group of parallel flat glass plates fixed to the parallel flat glass holding frame of the parallel flat glass driving unit, and 5 is a drive motor unit for rotationally driving the holding frame, 6
Is an optical low-pass filter rotation mechanism section, and an optical low-pass filter 7 is held in the central portion of the optical low-pass filter rotatably in the direction b in a predetermined angle range around the optical axis.

Next, the shapes of the parallel plate glass driving unit 3 and the parallel plate glass groups 4a to 4d will be described with reference to FIGS. FIG. 2 is a plan view of the parallel plate glass driving unit 3 as viewed from the lens group 1 side in a direction perpendicular to the optical axis principal plane (X direction in FIG. 1). In the figure, 4a to 4d are parallel plate glass groups, and in the state shown in the figure, the parallel plate glass 4a is located in the optical path range F. 12 is a holding frame for holding the parallel plate glass groups 4a to 4d, 12
a is a gear portion formed on the outer periphery of the holding frame 12,
Reference numeral b is a hole provided in the central portion of the holding frame 12, and the holding frame 12 is rotatably engaged with a rotating shaft 18 which is rotationally driven by the stepping motor 5.

Reference numeral 5 is a stepping motor for driving the parallel plate glass, 16 is an output shaft of the stepping motor 5, and 17 is a pinion engaged with the output shaft 16. The pinion 17 engages with the gear portion 12 a of the holding frame 12, and the holding frame 12 rotates according to the rotating operation of the stepping motor 5.

Reference numeral 18 denotes a rotary shaft that is rotatably engaged with the hole 12b of the holding frame 12 to hold the holding frame 12, and 19 is formed on a part of the holding frame 12 to detect the rotational position of the holding frame 12. Position detection holes for 2
Reference numeral 0 indicates an initialization sensor (photo sensor) that detects the position detection hole 19 and detects the initial rotation position of the holding frame 12.
It is.

FIG. 3 is a perspective view showing the outer appearance of the holding frame 12. Parallel plate glass groups 4a to 4d of this embodiment
Is a glass-molded parallel plate, but is not limited to this, and it is also possible to reduce the weight of the parallel plate by using a plastic resin, for example.

In the parallel plate glass groups 4a to 4d, the parallel plate glass 4a is a parallel plate glass positioned on the optical axis (on the line G in the figure) after initialization, and is held parallel to the optical axis main plane. Is attached to.

The parallel flat plate glass 4b is a parallel flat plate glass for changing the optical path in the vertical direction, and when it is located in the optical path (range F in FIG. 2), it has a predetermined number of pixels in the vertical direction. It is attached to the holding frame 12 with a predetermined angle inclined with respect to the vertical axis of the optical axis main plane so as to change the optical path.

The parallel flat plate glass 4c is a parallel flat plate glass for changing the optical path in the horizontal direction. When the parallel flat plate glass 4c is located in the optical path, the parallel flat plate glass 4c has a predetermined number of pixels in the horizontal direction (1 in this embodiment).
(Pixel) It is attached to the holding frame 12 so as to be inclined at a predetermined angle with respect to the vertical axis of the optical axis main plane so as to change the optical path.

The parallel plate glass 4d is a parallel plate glass for changing the optical path in both the vertical and horizontal directions, and when it is located in the optical path, it has a predetermined number of pixels in both the vertical and horizontal directions (in the present embodiment, the horizontal and horizontal directions). (1 pixel for each vertical)
It is attached to the holding frame 12 at a predetermined angle with respect to the vertical axis and the horizontal axis of the optical axis main plane so that the optical path can be changed.

In this embodiment, since the pixel shift of one pixel is performed, the number of divided parallel flat glass plates is four, and the shape and thickness of each parallel flat glass plate should be set to be the same. To reduce the number of parts manufactured.

Next, referring to FIG. 4, each parallel plate glass 4
The manner in which the optical path of light passing through a to 4d changes will be described.

4 (a) to 4 (d) are front views of the parallel plate glasses 4a to 4d as seen from the lens group 1 side when the parallel plate glasses 4a to 4d are located in the optical path. It is a figure, a right side view, and a top view.

FIG. 4A shows a state in which the parallel flat plate glass 4a is located in the optical path, and the light passing through the parallel flat plate glass 4a goes straight without changing the optical path. Figure 4 (b) shows
As shown in the right side view, since the parallel flat plate glass is inclined at a predetermined angle α with respect to the vertical axis, the light passing through the parallel flat plate glass 4b changes the optical path of a predetermined width in the arrow p direction shown in the front view. Show the situation.

As shown in the top view of FIG. 4 (c), since the parallel flat plate glass is inclined at a predetermined angle β with the vertical axis as the rotation axis, the light passing through the parallel flat plate glass 4c is shown in the front view. The manner in which the optical path of a predetermined width is changed in the direction of arrow q is shown.
4D, as shown in the right side view and the top view, the parallel flat glass 4 is inclined by a predetermined angle γ with respect to the vertical axis and is inclined by a predetermined angle δ with the vertical axis as a rotation axis.
7 shows how the light passing through d changes the optical path of a predetermined width in the direction of arrow r shown in the front view.

Next, the details of the optical low-pass filter rotation mechanism section 6 will be described with reference to FIG. FIG. 5A is a plan view of the optical low-pass filter rotation mechanism section 6 viewed from the optical axis principal plane (X direction in FIG. 1) on the lens group 1 side.

In the figure, reference numeral 7a denotes a movable low-pass filter, which has a shape in which one surface of the upper portion is notched, and the notched surface 41 is an ordinary ray when the upper surface is in a state parallel to the horizontal direction. The separation direction (direction of extraordinary ray) is 135 degrees with respect to the horizontal direction (X direction in FIG. 1) (FIG.
(Solid line position in (b)).

A fixed low-pass filter 7b (not shown) is fixed to the base 43 on the back side of the movable low-pass filter 7a in the drawing, and the direction of separation of ordinary rays (the direction of extraordinary rays) is shown in FIG. It is always 0 degrees (horizontal) when viewed from the X direction (FIG. 5 (c)).

Reference numeral 44 denotes an LPF (low pass filter) holder, in which the movable low pass filter 7a is fixed substantially in the center, a gear portion 44a is formed on the outer peripheral portion, and is rotatably held by the base 43. Further, a flange-shaped protrusion 44 b is formed on a part of the outer peripheral portion of the LPF holder 44. A pinion 45 is rotationally engaged with the gear portion 44a of the LPF holder 44, and is press-fitted into the output shaft of a stepping motor 46 for driving the optical low pass filter. 48
Is an initialization sensor that detects the initial position of the LPF holder 44.

In the above structure, when the movable low-pass filter 7a is in the position shown by the solid line in FIG. 5B, the cutoff frequency band of the spatial frequency is limited for both the horizontal and vertical components of the light passing through the low-pass filter. It is in the closed state, and it is counterclockwise from this position (Y direction in the figure)
The vertical component is canceled at the position rotated by 45 degrees (the position of the broken line in FIG. 5B), the cutoff frequency band of the spatial frequency is expanded, and high-resolution image information can be obtained. .

Next, with reference to FIGS. 6 to 11, a series of operations for shifting the pixels by the parallel plate glass will be described. FIG. 6 is a flowchart showing a process for initializing the parallel flat plate glass.

First, when the power is turned on, the initialization sensor 2
It is determined whether the output of 0 is HIGH or LOW (step S1), and if it is LOW (state where the initialization sensor 20 detects the position detection hole 19), step S5.
If it is HIGH (state where the initialization sensor 20 does not recognize the position detection hole 19), the process proceeds to step S2.

In step S2, the stepping motor 5 for driving the parallel plate glass is rotated in the CW direction (clockwise as viewed from the output shaft direction of the stepping motor), and in step S3, the output of the initialization sensor 20 is LOW. It is determined whether or not If the output of the initialization sensor is not LOW, step S2 is repeatedly executed, and if it is LOW, the process proceeds to step S4 to stop the stepping motor 5.

Next, in step S5, the output shaft of the stepping motor is in the CCW direction (counterclockwise direction when viewed from the output shaft direction of the stepping motor. See FIG. 10).
Then, in step S6, it is determined whether or not the initialization sensor output has become HIGH. When the output of the initialization sensor becomes HIGH, the stepping motor is stopped, the rotational position is recognized as the origin position by the control microcomputer, and the process proceeds to step S7.

In step S7, the step S
The stepping motor 5 is driven in the CCW direction by 4 steps from the origin position detected in 6, and the stepping motor 5 is stopped in step S8. This allows
The parallel plate glass 4a is positioned in the optical path (range F in FIG. 2), that is, the parallel plate glass is parallel to the optical axis principal plane, and the process is completed.

As described above, when the initialization of the parallel plate glass is completed, the number of drive pulses of the stepping motor and the rotation phase of the holding frame can be correlated, so that the number of steps of the stepping motor should be controlled. Thus, it is possible to arbitrarily set the rotation position of the parallel flat plate glass.

Next, the initialization processing of the optical low-pass filter rotation mechanism section 6 will be described with reference to FIG. FIG. 7 is a flowchart showing an initialization process of the optical low pass filter rotation mechanism section 6.

First, when the power is turned on, the initialization sensor 4
It is determined whether the output of 8 is HIGH or LOW (step S11), and LOW (the initialization sensor 48 is LP
If the protrusion 44b of the F holder 44 is detected), the process proceeds to step S15. If HIGH (state where the initialization sensor 48 does not detect the protrusion 44b), the process proceeds to step S12.

In step S12, the output shaft of the stepping motor 46 for driving the optical low pass filter is set to C.
It rotates in the CW direction, and in step S13, it is determined whether or not the output of the initialization sensor 48 has become LOW. If the output of the initialization sensor is not LOW, step S12 is repeatedly executed. If it becomes LOW, the process proceeds to step S14, and the stepping motor 46 is stopped.

Next, in step S15, the output shaft of the stepping motor is rotated by one step in the CW direction, and in step S16, it is determined whether or not the initialization sensor output has become HIGH. Initialization sensor output is HIGH
If so, the control microcomputer is caused to recognize this rotational position as the origin position, the process proceeds to step S17, and the stepping motor 46 is stopped. The state of the movable low-pass filter 7a at this time is the state of FIG. 5B, and the cut-off frequency band of the spatial frequency is limited.

When the above initialization processing of the optical low-pass filter is completed, the drive pulse number of the stepping motor and the rotational phase of the movable side low-pass filter can be correlated with each other. Therefore, the cut-off is controlled by controlling the step number of the stepping motor. It is possible to change the frequency band.

Next, with reference to FIGS. 8 and 9, the flow of a process for shifting the pixels and capturing the image information will be described.

FIG. 8 is a flowchart showing the operation of driving the parallel plate glass. FIG. 9 is a schematic diagram for capturing image information.

First, when the parallel plate glass and the optical low-pass filter have been initialized and the high image quality mode for image acquisition is selected, the movable-side low-pass filter 7a sets the cut-off frequency band of the spatial frequency. It is rotated to a position for enlarging (position of broken line in FIG. 5B) and stopped (see FIG. 11).

At the end of initialization of the parallel flat plate glass, the parallel flat plate glass 4a is in the optical path, and at this time, the surface normal of the parallel flat plate glass is parallel to the main plane of the optical axis. , The light passing through the parallel plate glass 4a goes straight. Therefore, in step S21 of FIG. 8, the image information of the first surface (address 1 in FIG. 9) is captured.

Next, in step S22, the stepping motor 5 for driving the parallel flat plate glass is set to 1 in the CCW direction.
It is driven to rotate 0 steps, and parallel flat glass 4 is placed in the optical path.
Position b. Next, returning to step S21, the image information of the second surface (address 2 in FIG. 9) shifted by one pixel in the vertical direction on the image pickup element surface is fetched.

When the image capturing by the vertical pixel shift is completed in this way, the process proceeds to step S22 again, and the stepping motor 5 for driving the parallel plate glass is rotationally driven by 10 steps in the CCW direction. This allows
The parallel flat plate glass 4c is located in the optical path, and the process returns to step S21, and the third surface (the third address in FIG. 9) horizontally shifted by one pixel from the second address in FIG. ) Image information is taken in.

Next, in step S22, the stepping motor 5 for driving the parallel flat plate glass is driven to rotate in the CCW direction by 10 steps. As a result, the parallel plate glass 4d is positioned in the optical path, the process returns to step S21, and the fourth surface (in FIG. 9), which is vertically displaced from the address 3 in FIG. The image information of address 4) is fetched.

When the acquisition of the image information of the fourth surface is completed, the stepping motor 5 is rotated in the CCW direction by 10 steps (step S22) and stopped (step S2).
3) When the stepping motor 5 is further rotated 10 steps in the CCW direction (step S24) and stopped (step S23), the initial state is restored.

When the acquisition of the image information for the four planes is completed as described above, the image information for the four planes is combined and output by a system incorporated in a computer (not shown).

FIG. 10 is a diagram showing the driving directions of the respective elements (holding frame, movable side low-pass filter) and the rotating directions of the stepping motors for driving the respective elements in this embodiment, and FIG. 10 (a) shows the holding frame. The operation direction, FIG. 11B shows the operation direction of the movable side low-pass filter. Both figures are viewed from the principal plane of the optical axis on the lens side.

In the present embodiment, the high resolution image information is read by shifting the pixel in units of one pixel, but the basic configuration is the same and the pixel shifting in any pixel unit is performed. It goes without saying that you can do it.

For example, if the number of parallel flat glass plates installed is changed from 4 to 16, the pixel shift can be performed in 0.5 pixel units, and the system can be expanded to a higher resolution. When such pixel shifting is performed in 0.5 pixel units, it is also possible to appropriately set the holding frame mounting angle for mounting the parallel flat plate glass of 16 surfaces and perform the pixel shift by the parallel flat plate glass having the same thickness. However, when performing pixel shifting in the same direction, the thickness of the parallel plate glass may be changed to set the pixel shifting amount.

For example, as described above in "Problems to be Solved by the Invention", since the optical path change amount by the parallel flat plate glass is δs = (1-1 / N) · d · θ, the parallel flat plate glass is Is directly proportional to the thickness d of, and if 0.5 pixel is d = 1 mm in the case of the same inclination, 1 pixel is d = 2 mm,
The thickness of 1.5 pixels may be set to d = 3 mm.

With this structure, it is possible to reduce the setting of the tilt angle of the holding frame even if the number of divisions is large, and therefore the holding frame can be made simple in structure. Cost reduction can be realized.

Further, since it is relatively easy to process the thickness of the parallel flat plate glass with high accuracy, it is possible to develop it as a system which can perform pixel shifting with higher accuracy. Further, it is possible to reduce the number of parts by integrally molding the parallel plate glass and the holding frame.

FIG. 11 is a flow chart showing the rotation operation of the optical low-pass filter in each of the high-quality mode and the normal mode at the time of capturing an image.

First, in step S31, it is determined whether the high image quality mode or the normal mode is selected as the operation mode. If the high image quality mode is selected, the process proceeds to step S32, and the movable low-pass filter 7a is selected. To the position where the cutoff frequency band expands.

On the contrary, when it is desired to return to the normal mode, the process proceeds to step S34, in which the parallel flat glass is rotated in the reverse direction to the position where the cutoff frequency band is limited. It is possible to improve the operability by interlocking the switching of the movable low-pass filter 7a with the pixel shifting by the rotation operation of the holding frame 12, but the switching mechanism of the movable low-pass filter 7a described above is pixel-shifted. It may be provided independently of and to be operated as necessary. Furthermore, when the focus is adjusted, the movable low-pass filter 7a is switched to expand the cut-off frequency band as an optical low-pass filter to cause moire, and fine adjustment of the focus can be performed to perform more accurate adjustment. .

[0083]

According to the first aspect of the present invention, an image pickup element for converting optical image information into an electric signal, a lens group for forming an optical image on the image pickup element, and an optical axis main body of the lens group. In an imaging device having an optical path changing means for shifting the optical path of light passing through the lens group, which has a light-transmitting flat plate inclined at a predetermined angle with respect to a plane, the optical path changing means is provided for the light passing through the lens group. At least one light-transmissive flat plate having a plurality of light-transmissive flat surfaces that can be arranged on the optical path by inclining at a predetermined angle with respect to the main optical axis planes of the lens groups; Since each has a light transmission plane switching means for switching and driving so as to be arranged on the optical path of light passing through the lens group, high resolution image information can be taken in at high speed by so-called pixel shifting.

According to the second aspect of the present invention, the light transmitting plane switching means has a light transmitting flat plate holding means for holding the at least one light transmitting flat plate, and the light transmitting flat plate holding means is rotated. Since each of the plurality of light transmitting planes is switched and arranged on the optical path of the light passing through the lens group, the high resolution image information can be captured at a high speed by so-called pixel shifting. .

According to the third aspect of the present invention, in the at least one light transmitting flat plate, the thickness in the optical axis direction at the formation portion of each of the plurality of light transmitting flat surfaces is the optical path of the light passing through the lens group. Is set so as to be shifted in a desired direction in a desired width, so that high-resolution image information can be captured at high speed and accurately by so-called pixel shifting.

According to the invention described in claim 4, since the at least one light transmitting plate is integrally formed with the light transmitting plate holding means, the number of parts can be reduced and the cost can be reduced. be able to.

According to the fifth aspect of the invention, since the plurality of light transmitting planes are integrally formed on one light transmitting flat plate, it is possible to reduce the number of parts and realize cost reduction. it can.

According to the sixth aspect of the present invention, the lens group has an optical low-pass filter for limiting the spatial frequency of the optical image information of the light incident on the image pickup element, and the optical low-pass filter is the photographing light. Since it is rotatably held about the axis, it is possible to capture image information of higher resolution at high speed.

According to the seventh aspect of the present invention, the lens group changes the cut-off frequency characteristic by rotating the optical low-pass filter, so that image information of higher resolution can be captured at high speed. it can.

[Brief description of the drawings]

FIG. 1 is a plan view showing a schematic configuration of an image pickup apparatus according to an embodiment of the present invention.

FIG. 2 is a plan view of a parallel plate glass driving unit.

FIG. 3 is a perspective view showing an appearance of a holding frame.

FIG. 4 is a schematic diagram showing a rotation position of a holding frame and a change in optical path.

FIG. 5 is a plan view showing a rotation mechanism section of the optical low-pass filter.

FIG. 6 is a flowchart showing an initialization process of parallel flat glass.

FIG. 7 is a flowchart showing initialization processing of an optical low-pass filter.

FIG. 8 is an operation flowchart for driving a parallel plate glass.

FIG. 9 is a schematic diagram for capturing image information.

FIG. 10 is a schematic view showing the driving directions of the holding frame and the optical low-pass filter, and the rotation directions of the stepping motors for driving each element.

FIG. 11 is a flowchart showing the rotation operation of the optical low-pass filter in each of the high-quality mode and the normal mode.

FIG. 12 is a plan view showing an example of the arrangement of an optical system and an image pickup element of a conventional image pickup apparatus.

FIG. 13 is an explanatory diagram showing the principle of shifting the optical path by means of parallel plate glass.

FIG. 14 is an explanatory diagram illustrating a pixel array of an image sensor and an example of apertures.

FIG. 15 is a plan view showing an example of the arrangement of an optical system and an image pickup element of a conventional image pickup apparatus.

FIG. 16 is a plan view of a cam used in a conventional image pickup apparatus as seen from the front side of the output shaft of a stepping motor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Lens group 2 Image sensor 3 Parallel plate glass drive part 4 Parallel plate glass group 5 Optical low pass filter rotation mechanism part 6 Optical low pass filter 12 Holding frame 12a Gear part 12b Hole part 15 Parallel plate drive stepping motor 16 Output shaft 17 Pinion 18 Rotation axis 19 Position detection hole 20 Initialization sensor 7a Movable low-pass filter 7b Fixed low-pass filter 43 Base 44 LPF holder 45 Pinion 46 Stepping motor 44b Protrusion 48 Initialization sensor 201 Lens group 202 Image sensor 203 First parallel Flat glass holding frame 204 First parallel flat glass 205, 206 Rotation axis 207 Second parallel flat glass holding frame 208 Second parallel flat glass 209, 210 Rotation axis 211 Optical low pass filter 231 Parallel Plate glass 232 First frame 233, 234 Rotating shaft 235 First cam pin 236 First cam 237 Second frame 238, 239 Rotating shaft 240 Second cam pin 241, 242 Rotating shaft 243, 244 Bearing portion 245, 246 Spring 247, 248 Stepping motor 249 Second cam 250 base

Claims (7)

[Claims] 1. An image pickup element for converting optical image information into an electric signal, a lens group for forming an optical image on the image pickup element, and light transmission inclined at a predetermined angle with respect to a principal plane of an optical axis of the lens group. In an imaging device having a flat plate and an optical path changing unit that shifts an optical path of light passing through the lens group, the optical path changing unit includes an optical axis main unit of the lens group on an optical path of light passing through the lens group. At least one light-transmissive flat plate having a plurality of light-transmissive flat faces that can be arranged with a predetermined angle of inclination with respect to the flat face; and a plurality of light-transmissive flat plates that pass through the lens group. An image pickup apparatus comprising: a light transmission plane switching unit that is driven to switch so as to be arranged on an optical path. 2. The light transmission plane switching means includes light transmission flat plate holding means for holding the at least one light transmission flat plate, and the light passing through the lens group is rotated by rotating the light transmission flat plate holding means. 2. Each of the plurality of light transmitting planes is switched and arranged on the optical path of 1.
An imaging device according to any one of the preceding claims. 3. The at least one light-transmissive flat plate has a thickness in the optical axis direction at each formation portion of the plurality of light-transmissive flat surfaces that shifts an optical path of light passing through the lens group in a desired width by a desired width. The image pickup apparatus according to claim 1, wherein the image pickup apparatus is set as follows. 4. The image pickup apparatus according to claim 1, wherein the at least one light transmitting plate is integrally formed with the light transmitting plate holding means. 5. The light-transmitting planes are integrally formed on one light-transmitting flat plate.
The image pickup apparatus according to claim 4. 6. The lens group includes an optical low-pass filter that limits a spatial frequency of optical image information of light incident on the image sensor, and the optical low-pass filter is rotatable about a photographing optical axis as a center. The imaging device according to claim 1, wherein the imaging device is held. 7. The image pickup apparatus according to claim 1, wherein the lens group changes the cutoff frequency characteristic by rotating the optical low pass filter.