JPH0980344A - Optical system for electronic image pickup device having mirror scan function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an optical system which can have a substantial number of pixels larger than the of HDTV and almost as large as that of silver salt by using an image pickup device of the NTSC, PAL, and HDTV standards by using an optical system having a mirror scan function meeting specific conditions. SOLUTION: This system consists of an image formation optical system composed of a 1st negative lens group, a rotary mirror 1, an effective diaphragm 2, and a 2nd positive lens group 3 in order from the object side, an optical low-pass filter 4, a half-mirror 5, and electronic image pickup devices 6 and 7. And, conditions of an inequality I 7mm<d <25mm, an inequality II 0.1<n1 -n2 <0.4, and an inequality III 2<(r1 +r2 )/(r1 -r2 )<10 are met at the same time. In the inequalities, (d) is the distance between the rotation center position of the rotary mirror 1 and the pupil position of the image formation optical system viewed from the said position, n1 and n2 are the refractive indexes of the positive lens and negative lens arranged on the most object sides respectively, and r1 and r2 are the radii of curvature of the body side and image side of the positive lens arranged on the most object side.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an optical system for a high-definition electronic image input device.

[0002]

2. Description of the Related Art Electronic images can be processed in a wide variety of ways, and in recent years, they have been increasingly used not only as photographs but also as input information for computers. However, an electronic image obtained by the conventional electronic image pickup device has a very small number of pixels in the image pickup device as compared with a silver halide photograph, and thus it is impossible to take an image of a character or a fine pattern. Therefore, it is conceivable to use an HDTV standard image pickup device, but the image pickup area increases and the optical system also increases in size, but the number of pixels is still insufficient.
In addition, a scanner using a line sensor has a very slow capturing speed, and it is difficult to capture a three-dimensional object.

[0003]

SUMMARY OF THE INVENTION In view of the above problems of the prior art, the present invention provides a conventional high-definition electronic image input device as compact and inexpensive as a conventional still video camera. It is an object of the present invention to provide an optical system that can use an image pickup device of NTSC, PAL, and HDTV standards and have a substantial number of pixels equal to or higher than the HDTV standard and equivalent to silver salt.

[0004]

In order to achieve the above object, an optical system for an electronic image pickup device having a mirror scan function according to the present invention has a negative refracting power in the order from the object side to the most object side. A first lens group including a negative lens, a rotatable mirror for bending an optical axis from an object point, an aperture stop, and a second lens group having a positive refracting power that is partially or wholly movable on the optical axis. And an electronic device that receives light that has passed through the imaging optical system, and the following conditional expressions are satisfied at the same time. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 2 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <10 where d is the rotation center position of the rotatable mirror. The distance from the position to the pupil position of the imaging optical system viewed from this position, n ₁ is the refractive index of the positive lens arranged closest to the object, and n ₂ is the refractive index of the negative lens arranged closest to the object. , R ₁ ,
r ₂ is the object side of the positive lens arranged closest to the object side,
The radius of curvature on the image side is shown respectively.

Further, the optical system of the present invention, in order from the object side,
A rotatable mirror for bending the optical axis from the object point, a first lens group having a negative refractive power and having a positive lens closest to the object side, an aperture stop, and a part or the whole of which can be moved on the optical axis. An image forming optical system including a second lens group having a positive refracting power and an electronic device that receives light transmitted through the image forming optical system are arranged and configured, and simultaneously satisfy the following conditional expressions. Even in this case, the above object can be achieved. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 −3 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <1, where d is the rotation center position of the rotatable mirror. And the distance from the position to the pupil position of the imaging optical system viewed from this position, n ₁ is the refractive index of the positive lens arranged closest to the object, and n ₂ is the refraction of the negative lens arranged closest to the object. Rate, r ₁ ,
r ₂ is the object side of the positive lens arranged closest to the object side,
The radius of curvature on the image side is shown respectively.

Further, in the optical system of the present invention, a direction in which the optical axis is bent and a direction in which the optical axis is passed are provided between the electronic imaging device and the imaging optical system including a rotatable mirror for bending the optical axis from the object point. In an optical system for an electronic image pickup device having a mirror scan function in which a semi-transparent mirror that divides light into two is provided, a plurality of shots are performed and each image is electrically bonded to form one screen through this mirror scan. At this time, when the number of shots is three or more, the long side direction of the electronic image pickup device is aligned with a direction substantially parallel to the rotation axis of the rotatable mirror, and the optical axis of the semi-transparent mirror is changed. The folding direction is perpendicular to the rotation axis of the rotatable mirror. When the number of shots is 3 or less, the long side direction of the electronic image pickup device is aligned with the direction substantially perpendicular to the rotation axis of the rotatable mirror, and the optical axis of the semi-transparent mirror is changed. The folding direction is parallel to the rotation axis of the rotatable mirror.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION In an optical system for an electronic image pickup device having a mirror scan function according to the present invention, a two-dimensional device having a small image pickup area but a small number of pixels as an electronic image pickup device and a performance suitable for this device. An imaging system incorporating an imaging optical system and a rotating mirror is adopted, one object (subject) having a large angle of view is divided into several areas, and the rotating mirror is rotated correspondingly. Once captured as multiple images, image processing and stitching them together 1
It is designed to form one image.

That is, FIG. 1 is a conceptual diagram showing the construction of the optical system of the present invention. The optical system of the present invention has a negative refractive power in order from the object side (not shown) and has a negative lens closest to the object side. A first lens group (not shown), a rotating mirror 1 for bending an optical axis L _C from an object point, an aperture stop 2, and a positive refracting power that can be partially or wholly moved on the optical axis L _C. An image forming optical system including a second lens group 3 having an optical path, an optical low-pass filter 4 utilizing the birefringence of a crystal, a semi-transparent mirror 5 that divides an optical path into a bending direction and a transparent direction, and a semi-transparent mirror 5. Electronic image pickup devices 6 and 7 arranged at conjugate positions on the divided optical path are arranged. FIG.
Is a diagram for explaining the concept, and the traveling direction of the incident light on the rotating mirror 1 is different from the actual direction due to the limitation of illustration.

Therefore, the optical system according to the present invention can use a low-priced image pickup device and further reduce the required image circle, so that a compact image forming optical system can be realized. However, the optical system of the present invention has the following serious problems in joining the images. Since the tilt angle is different for each of the divided images, graphic distortion occurs after the images are joined. Further, even if the object to be photographed is a plane, the object distance is slightly deviated with the rotation of the mirror, and it is impossible to focus uniformly on the entire screen. When distortion occurs due to the imaging optical system, it becomes impossible to join images. If parallax occurs in the portions of adjacent images that are in contact with each other, it becomes impossible to join the images.

However, the above-mentioned problem of occurrence of distortion can be corrected by digitizing the image signal and performing processing such as coordinate conversion, and after the correction processing, the images are joined together. The above problem can be solved by Also, of the focus shifts due to tilting, the focus shifts on the entire screen can be dealt with by setting the specifications so that they are within the depth of focus because the shifts are minute. Regarding the problem that the object distance shifts with the rotation of the mirror, focus adjustment may be performed each time the mirror rotates, but at that time, the size of the image changes due to focusing, and similarly correction by changing the specification setting is necessary.
In this case, since the focus adjustment amount is very small,
If the image-side chief ray is almost parallel to the optical axis,
The correction is virtually unnecessary.

Regarding the above-mentioned problem of parallax,
Unlike the problem of, because electrical correction is impossible,
This must be resolved first.
The cause of the parallax is that the center of rotation of the mirror is far from the entrance pupil of the imaging optical system. Therefore, as long as a normal lens system is used as the imaging optical system, this problem cannot be solved. Therefore, in the present invention, in order to scan an object to be photographed, as shown in FIG.
After the rotating mirror for bending the optical axis from the object point, the entire optical system is configured so that the optical system of the front diaphragm, that is, the optical system with the aperture diaphragm on the object side of the imaging optical system can be arranged. The center of rotation of the mirror and the entrance pupil of the optical system can be configured to be as close to each other as possible. by this,
The parallax can be corrected to a level that has no practical effect.

On the other hand, various optical elements such as various filters are often inserted between the imaging optical system and the electronic image pickup device, and the size of the effective image pickup surface of the electronic image pickup device is gradually decreasing in recent years. Therefore, the imaging optical system is required to have a large back focus length to focal length ratio. Therefore, in the present invention, how to arrange the aperture stop and the rotary mirror with respect to the so-called retrofocus type lens is a structural point.

The first method is, in order from the object side, a first lens group consisting of two lenses, a negative lens and a positive lens, having a negative refracting power as a whole, and an object for scanning the object. A mirror scan in which a rotatable mirror for bending an optical axis from a point, an aperture stop, and a second lens group having a positive refracting power capable of moving partly or wholly along the optical axis are arranged. A retro-focus type imaging optical system with functions was adopted. With a retrofocus type lens, it is extremely difficult to use a front diaphragm. Therefore, in a typical retrofocus type, the distance between the first lens group having a negative refracting power and the second lens group having a positive refracting power is large. The rotating mirror and the aperture stop are provided here by taking advantage of the wide range. In the optical system configured as described above, it is preferable that the following conditional expressions are simultaneously satisfied. 7 mm <d <25 mm (1) 0.1 <n ₁ -n ₂ <0.4 (2) 2 <(r ₁ + r ₂ ) / (r ₁ -r ₂ ) <10 (3) However, d is the distance between the rotation center position of the rotatable mirror and the pupil position of the image forming optical system viewed from this position, and n ₁ is a positive value arranged closest to the object side. The refractive index of the lens, n ₂ is the refractive index of the negative lens arranged closest to the object side, r ₁ ,
r ₂ is the object side of the positive lens arranged closest to the object side,
The curvature radii on the image side are shown (hereinafter the same).

Further, the above d, n ₁ -n ₂ or (r ₁ +
It is more preferable that any of the values of r ₂ ) / (r ₁ −r ₂ ) satisfy the following conditions. 12 mm <d <23 mm (4) 0.15 <n ₁ -n ₂ <0.4 (5) 3 <(r ₁ + r ₂ ) / (r ₁ -r ₂ ) <8 ... (6)

Conditional expression (1) defines the distance between the center of rotation of the rotating mirror and the position of the pupil image of the imaging optical system as seen from that position. When the value goes below the lower limit of the range of possible values in (1), there is insufficient space for the rotating mirror to rotate, and mirror scanning becomes impossible. On the other hand, if the value of d exceeds the upper limit, the mutual parallax of individual images formed by pasting together becomes unacceptable. Conditional expression (2) defines the difference in refractive index between the positive lens and the negative lens arranged closest to the object side, and in the optical system of the present invention, a large positive Petzval sum is likely to occur. Is n ₁ −
It is preferable to set the value of n ₂ to be large.
If the value of n ₁ -n ₂ is below the lower limit of the range of values that conditional expression (2) can take, a large Petzval sum is likely to occur, which is not suitable. On the other hand, the upper limit of the value of n ₁ -n ₂ may be the maximum value peculiar to the lens material forming the optical system of the present invention. Conditional expression (3) defines the shape factor of the positive lens arranged closest to the object side, and is (r ₁ + r ₂ ).
If the value of / (r ₁ −r ₂ ) is below the lower limit of the range of values that conditional expression (3) can take, it becomes difficult to correct distortion. On the other hand, if the value of (r ₁ + r ₂ ) / (r ₁ −r ₂ ) exceeds the upper limit, it becomes difficult to correct spherical aberration and coma.

As a second method of the present invention, in order from the object side, a first lens group having a negative single lens and a rotation for bending an optical axis from an object point to scan the object. A movable mirror, a second lens group having a positive single lens, an aperture stop, and a third lens group having a positive refracting power that is partially or wholly movable on the optical axis. A retrofocus type imaging optical system with a mirror scan function was adopted. As a result, the total length of the optical system and the front lens diameter can be made smaller than in the first method. Further, it is preferable that this optical system simultaneously satisfies the following conditional expressions. 7 mm <d <25 mm (1) 0.1 <n ₁ -n ₂ <0.4 (2) 1 <(r ₁ + r ₂ ) / (r ₁ -r ₂ ) <3 ... (7) Furthermore, the d, n ₁ -n _2, or _{(r 1 + r 2) /} (r
_It is more preferable that any of the values of ₁₋ r ₂ ) satisfy the following conditions. 10 mm <d <20 mm ··· (8) 0.2 <n ₁ −n ₂ <0.4 ··· (9) 1.2 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ). <2 ... (10) The reason why the conditional expressions (1) and (2) are defined is as described above, and the reason why the conditional expression (7) is defined is the case of the conditional expression (3). Is the same as.

The third method is, in order from the object side, a rotatable mirror for bending the optical axis from the object point to scan the object, two or less negative lenses and one positive lens. A first lens group having a negative refracting power as a whole, an aperture stop, and a second lens group having a positive refracting power that is partially or wholly movable along the optical axis. A retrofocus type imaging optical system with a mirror scan function was adopted. As a result, the total length of the optical system and the diameter of the front lens can be made smaller than in the second method. Further, it is preferable that this optical system simultaneously satisfies the following conditional expressions. 7mm <d <25mm ···· (1 ) 0.1 <n 1 -n 2 <0.4 ···· (2) -1 <(r 1 + r 2) / (r 1 -r 2) < 1 ... (11) Further, the above d, n ₁ -n ₂ , or (r ₁ + r ₂ ) / (r
_It is more preferable that any of the values of ₁₋ r ₂ ) satisfy the following conditions. 15mm <d <23mm ···· (12 ) 0.15 <n 1 -n 2 <0.4 ···· (5) 0 <(r 1 + r 2) / (r 1 -r 2) <1 (13) The reason why the conditional expressions (1) and (2) are defined is as described above, and the reason why the conditional expression (11) is defined is the same as in the case of the conditional expression (3). Is.

Further, in the image forming optical system adopted in the third method, in order from the object side, a rotatable mirror for bending an optical axis from an object point, a positive lens, and a convex surface facing the object side. And a negative meniscus lens having a negative refracting power as a whole, an aperture stop, a negative lens and three positive lenses and a positive lens arranged closest to the object side on the optical axis. If the second lens group that is movable and has a positive refracting power as a whole is disposed, it is compact and the imaging performance is the same as that shown in the third method.
The part having a function as an imaging optical system becomes simpler. It is preferable that this optical system simultaneously satisfies the following conditional expressions. 7mm <d <25mm ···· (1 ) 0.1 <n 1 -n 2 <0.4 ···· (2) -3 <(r 1 + r 2) / (r 1 -r 2) < 1 ... (14) Further, the above d, n ₁ -n ₂ , or (r ₁ + r ₂ ) / (r
_It is more preferable that any of the values of ₁₋ r ₂ ) satisfy the following conditions. 12mm <d <20mm ···· (15 ) 0.2 <n 1 -n 2 <0.4 ···· (9) -1.5 <(r 1 + r 2) / (r 1 -r 2 ) <-0.6 ... (16) The reason why the conditional expressions (1) and (2) are defined is as described above, and the reason that the conditional expression (14) is defined is the conditional expression ( This is similar to the case of 3).

The optical system having the mirror scan function as in the present invention is characterized by the conditional expression (1) defined so as not to generate parallax, and the purpose is only to adopt the mirror scan function. For example, conditional expression (2) that defines the secondary purpose of improving the perfection of aberration correction,
(3) is not particularly necessary.

Further, as described above, the optical system for the electronic image pickup apparatus having the mirror scanning function according to the present invention has the difference between the position where the rotary mirror is arranged and the pupil image position of the image forming optical system viewed from that position. Is configured to be as small as possible.
Therefore, the parallax can be suppressed to a level at which there is no practical problem.

By the way, the rotating direction of the rotating mirror is 1
If limited to a direction, a wide angle of view is obtained only in that direction, but the angle of view with respect to the vertical direction remains narrow. Therefore, two electronic image pickup devices (hereinafter referred to as CCDs) are arranged in a direction perpendicular to the rotation direction of the mirrors. However, when the CCDs are arranged side by side on the same plane, the effective images cannot be connected. Therefore, in the present invention, a semi-transparent mirror that divides the light is provided between the image forming optical system and the image forming point, and the semi-transparent mirror is arranged at a conjugate position on each optical axis divided by two. By arranging CCDs and further connecting the images obtained by each CCD, the angle of view in the direction parallel to the rotation axis direction of the rotating mirror is also secured so that the aspect ratio of the images can be balanced. are doing. That is, as shown in FIG. 2A, even if two CCDs 6 and 7 are arranged side by side, the light receiving portions 7a and 7b cannot be in contact with each other. Therefore, the CCD 6 and the CCD 7 are shown in FIG. As described above, the two CCDs 6 and 7 are combined by arranging them at conjugate positions on the optical axis divided in two directions and synthesizing the images captured by the CCDs 6 and 7, respectively.
The positional relationship is set so that the light-receiving parts of are in contact with each other. Therefore, as shown in FIG. 2B, a combined vertically long light receiving portion is formed.

The effective image pickup surface of the CCD is usually rectangular, but if one screen is formed by four or more shots (one shot means one shooting operation) through mirror scan, the length of one CCD is long. It is preferable to make the side direction coincide with the direction parallel to the rotation direction of the rotating mirror, which reduces the number of screen divisions. On the other hand, in the case of two shots, from the viewpoint of efficiently using the image circle, it is preferable to match the long side direction of the CCD with the direction substantially perpendicular to the rotation axis of the rotating mirror. In this case, it is more efficient to bend the optical axis by the semi-transparent mirror in a direction parallel to the plane including the rotation direction of the mirror, because the thickness of the semi-transparent mirror is reduced. In the case of 3 shots,
Since there is almost no difference in efficiency, any of the above may be used.

Next, since the CCD is used, a filter for preventing the aliasing distortion is required, and it is usually inserted between the imaging optical system and the CCD. In that case, the filter is more than the semi-transparent mirror. If the filter is inserted on the object side, only one set of filters is required. Further, in this case, the polarization action of the filter and the semi-transparent mirror affects the light splitting ratio by the semi-transparent mirror. Therefore, the azimuth angle of the orthographic projection image of the crystal axis of the optical low-pass filter, which is arranged at the position closest to the semi-transparent mirror, on the image plane of the imaging optical system is the rotation axis of the mirror. It is necessary to dispose the optical low-pass filter so that it is 40 to 50 degrees.

The optical low-pass filter is made of a crystalline material, and in the present invention, it is used to separate an incident ray into the low-pass filter into an ordinary ray and an extraordinary ray which are polarized perpendicularly to each other. . On the other hand, the semi-transparent mirror also has a polarization effect. Therefore, in order to generate the same amount of P-polarized light and S-polarized light of the reflected light of the semi-transparent mirror, the ordinary ray and the extraordinary ray have an angle of 40 to 50 degrees with respect to the rotation axis of the rotating mirror. It is necessary to set it so that it is emitted from the optical low-pass filter. By doing so, even if an optical element having a polarizing action, such as the semi-transparent mirror, is inserted into the optical path of the optical system of the present invention, it can function normally as an optical low-pass filter.

The basic structure of the present invention will be described below with reference to FIG.

3A and 3B are lens configuration diagrams of an optical system for an electronic image pickup device having a mirror scan function according to the present invention. FIG. 3A is a sectional view taken along the optical axis of the optical system, and FIG. A view showing a cross section including the rotation axis of the rotating mirror when viewed (note that the direction of the mirror 1 is different from the actual direction due to the limitation of the drawing), (c) is the rotation axis of the rotating mirror when viewed from the side. It is a figure which shows a vertical cross section. FIG. 4 is a diagram for explaining an image pickup state of the object image formed by the optical system of the present invention by the CCD.

As shown in FIGS. 3 (a) to 3 (c), in the optical system of the present invention, the first lens group having negative refracting power and including the negative lens closest to the object side in order from the object side (not shown). (Not shown), rotating mirror 1, aperture stop 2, second lens group 3,
An optical low-pass filter 4 and a semi-transparent mirror 5 are arranged, and CCDs 6 and 7 are provided in the emission direction of the semi-transparent mirror 5. The second lens group 3 includes, in order from the object side, a cemented negative lens 3a composed of a positive lens and a negative lens, a matching positive lens 3b composed of a negative lens and a positive lens, and a cemented positive lens 3c composed of a positive lens and a negative lens. And are arranged so that a part or the whole of these lenses can move on the optical axis L _C for focusing. Also, when the squareness of the incident light on the CCDs 6 and 7 is severely restricted, or when the semi-transparent mirror 5 is inserted on the image side of the second lens group 3 to divide the optical path, the exit pupil of the lens group is Between the semitransparent mirror 5 and the CCD 6 and between the semitransparent mirror 5 and the C so as to be telecentric as much as possible.
A lens 8 having a positive refracting power between the CD 7 and
It is preferable that 9 is additionally inserted. As a result, not only the light rays emitted from the optical system of the present invention are made to enter the image pickup surface substantially at right angles, but also changes in image size due to focusing can be suppressed.

In the optical system of the present invention, as shown in FIG. 3B, the semi-transparent mirror 5 causes the optical path to the direction of the CCD 6 and the CCD 7.
The direction is divided into: Then, FIG. 4 shows an object image formed by the second lens group 3 of the imaging optical system,
The upper part A of this object image passes through the semi-transparent mirror 5 and the CCD 6
The lower part B is bent by the semi-transparent mirror 5 and is imaged by the CCD 7.
The arrow C in the figure indicates the direction of scanning by the rotating mirror 1.

The present invention will be described in detail below with reference to the illustrated embodiments.

First Embodiment FIG. 5 is a view showing a cross section perpendicular to the rotation axis of the rotating mirror of the optical system according to the present embodiment. In the optical system of this embodiment,
First, a first lens group 11 having a negative refracting power as a whole, composed of a negative meniscus lens 11a having a convex surface facing the object side and a positive meniscus lens 11b having a concave surface facing the object side Mirror 12, aperture stop 13, and cemented negative lens 14 of negative lens and positive lens
a, a cemented positive lens 14b of a negative lens and a positive lens,
A second lens having a positive refractive power as a whole, which is composed of a positive lens 14c and a cemented positive lens 14d composed of a positive lens and a negative lens.
The lens group 14 is arranged to form an imaging optical system 21. Further, each of the lenses constituting the second lens group 14 can be moved partially or entirely on the optical axis L _C. Further, on the exit side of the second lens group 14, an infrared cut filter or a λ / 4 plate 15, an optical low-pass filter 16 made of a birefringent plate such as a quartz plate, and a prism 17 made of a beam splitter including a semi-transmissive surface. Are arranged. CCD 18, 1 in the exit direction of the prism 17
9 is provided, and a cover glass (or a positive lens) 20 is arranged between the prism 17 and the CCD 18 (note that although not shown, the prism 17 and the CCD 19).
A similar cover glass or positive lens is placed between and).

The rotation axis of the rotary mirror 12 is in the direction perpendicular to the paper surface, and the extension line of the optical axis L _C of the second lens group 14 is at the position intersecting the mirror surface. The optical low-pass filter 16 is composed of one sheet or a plurality of filters having different crystal axis directions bonded together, and the crystal axis of the filter closest to the prism 17 forms about 45 degrees with respect to the plate surface thereof. As shown in FIG. 6, the orthographic projection of the crystal axis on the plate surface is substantially 45 degrees with respect to the rotation axis of the rotating mirror 12, and the incident light is divided into an ordinary ray and an extraordinary ray and the CCD 1
It has a function to form a slightly shifted double image on the surfaces 8 and 19.

The optical system of this embodiment is designed to photograph the entire object image in two shots (two photographing operations).
The CCD 18 to which the light passing through the prism 17 is incident is arranged so that the long side of its light-receiving surface is perpendicular to the rotating mirror 12, while the CCD 19 has its light-receiving surface oriented accordingly. Therefore, FIG. 7 shows the imaging optical system 21.
The upper step A of this object image is taken by the CCD 18 without passing through the prism 17, and the lower step B is bent by the prism 17 and taken by the CCD 19. It was done. The arrow C in the figure indicates the direction of scanning by the rotating mirror 12. In this way, in the optical system of this embodiment, the four images are combined to reproduce the object image.

In the optical system of the present embodiment shown in FIG. 5, the rotating mirror 12 is in the standard state at the position indicated by the broken line (the position where the angle of the mirror surface with respect to the optical axis L _C is 45 degrees). In this state, the optical axis L _C can be bent below the 90-degree rotating mirror 12. Further, the position indicated by the solid line is the state in which the rotating mirror 12 is rotated to the maximum, and is the state in which the chief ray having the maximum image height is rotated by half the size of the angle formed with the optical axis L _C. The rotating mirror 12 can of course be rotated in the opposite direction to the illustrated direction.

The following are numerical data of optical elements such as lenses constituting the optical system according to this embodiment. _{d = 15mm, n 1 -n 2} = 0.20207 (r 1 + r 2) / (r 1 -r 2) = 6.375

R ₁ = 42.8695 d ₁ = 1.5000 n ₁ = 1.60311 ν ₁ = 60.70 r ₂ = 19.0755 d ₂ = 10.1431 r ₃ = -38.0797 d ₃ = 2.1000 n ₃ = 1.80518 ν ₃ = 25.43 r ₄ = -27.7527 d ₄ = 28.0000 r ₅ (aperture diaphragm 13) = ∞ d ₅ = 4.5000

R ₆ = -10.5481 d ₆ = 0.9000 n ₆ = 1.60311 ν ₆ ＝ 60.70 r ₇ ＝ 7.5000 d ₇ ＝ 3.0000 n ₇ = 1.59270 ν ₇ ＝ 35.30 r ₈ ＝ 275.3552 d ₈ ＝ 0.7533 r ₉ ＝ -124.5995 d ₉ = 1.0000 n ₉ = 1.84666 ν ₉ ＝ 23.78 r ₁₀ ＝ 33.1292 d ₁₀ ＝ 3.1000 n ₁₀ ＝ 1.51633 ν ₁₀ ＝ 64.15

R ₁₁ = -14.8105 d ₁₁ = 0.1500 r ₁₂ = 57.3145 d ₁₂ = 2.5000 n ₁₂ = 1.69680 ν ₁₂ = 55.53 r ₁₃ = -29.3496 d ₁₃ = 0.1500 r ₁₄ = 32.6981 d ₁₄ = 4.2000 n ₁₄ = 1.9680 ν _{14 = 55.53 r 15 = -14.0000 d} 15 = 1.2000 n 15 = 1.84666 ν 15 = 23.78

R ₁₆ = -28.9975 d ₁₆ = 2.0000 r ₁₇ = ∞ d ₁₇ = 5.0000 n ₁₇ = 1.54771 ν ₁₇ = 62.84 r ₁₈ = ∞ d ₁₈ = 2.2400 n ₁₈ = 1.54771 ν ₁₈ = 62.84 r ₁₉ = ∞ d ₁₉ = 10.0000 n ₁₉ = 1.51633 ν ₁₉ = 64.15 r ₂₀ = ∞ d ₂₀ = 3.6100

R ₂₁ = ∞ d ₂₁ = 0.7500 n ₂₁ = 1.48749 ν ₂₁ = 70.21 r ₂₂ = ∞ d ₂₂ = 1.4000 r ₂₃ (CCD 18, 19) = ∞

Second Embodiment FIG. 8 is a view showing a cross section perpendicular to the rotation axis of the rotating mirror of the optical system according to the present embodiment. In the optical system of this embodiment,
First, in order from the object side (not shown), the first lens group 22 composed of a negative meniscus lens having a convex surface facing the object side, the rotating mirror 12, the second lens group 23 composed of a positive lens, the aperture stop 13, and the negative lens and the positive lens. Negative lens with lens 2
An image forming optical system 21 is configured by arranging a third lens group 24 having a positive refracting power as a whole and including a positive lens 24b, a positive lens 24b, and a positive lens 24c cemented with a positive lens and a negative lens. Further, each of the lenses constituting the third lens group 24 can be partially or wholly moved on the optical axis L _C. Further, on the exit side of the third lens group 24, an infrared cut filter or a λ / 4 plate 15, an optical low-pass filter 16 made of a birefringent plate such as a quartz plate, and a prism 17 made of a beam splitter including a semi-transmissive surface.
Is arranged. CCD 1 in the exit direction of prism 17
8 and 19 are provided, and a cover glass (or a positive lens) 20 is disposed between the prism 17 and the CCD 18 (note that the prism 17 and the CC are not shown).
A similar cover glass or positive lens is also arranged between D19).

Further, the rotation axis of the rotary mirror 12 is in the direction perpendicular to the paper surface, and the extension line of the optical axis L _C of the third lens group 24 is at the position intersecting the mirror surface. The optical low-pass filter 16 is composed of one sheet or a plurality of filters having different crystal axis directions bonded together, and the crystal axis of the filter closest to the prism 17 forms about 45 degrees with respect to the plate surface thereof. As shown in FIG. 9, the orthographic projection of the crystal axis on the plate surface is substantially 45 degrees with respect to the rotation axis of the rotating mirror 12, and the incident light is divided into an ordinary ray and an extraordinary ray and the CCD 1
It has a function to form a slightly shifted double image on the surfaces 8 and 19.

The optical system of this embodiment is also adapted to photograph the entire object image in two shots (two photographing operations).
The CCD 18 to which the light passing through the prism 17 is incident is arranged so that the long side of its light-receiving surface is perpendicular to the rotating mirror 12, while the CCD 19 has its light-receiving surface oriented accordingly. Therefore, FIG. 10 shows the imaging optical system 2
1 shows the object image formed by No. 1, the upper step A of this object image is taken by the CCD 18 without passing through the prism 17, and the lower step B is the prism 17
It is bent by and is imaged by the CCD 19. The arrow C in the figure indicates the direction of scanning by the rotating mirror 12. In this way, in the optical system of this embodiment, the four images are combined to reproduce the object image.

In the optical system of the present embodiment, as shown in FIG. 8, the rotary mirror 12 is bent at 45 degrees with respect to the optical axis L _C , and the optical axis can be bent below the 90-degree rotary mirror 12. . Further, the rotating mirror 12 should rotate within the range of half the angle formed by the principal ray with the maximum image height with the optical axis L _C from the position shown in the figure, as in the optical system shown in the first embodiment. You can do it.

The following are numerical data of optical elements such as lenses that constitute the optical system according to the present embodiment. _{d = 12.872mm, n 1 -n 2} = 0.31769 (r 1 + r 2) / (r 1 -r 2) = 1.540

[0045] _{r 1 = 58.8822 d 1 = 1.2000} n 1 = 1.48749 ν 1 = 70.21 r 2 = 12.8873 d 2 = 20.0000 r 3 = -77.2783 d 3 = 1.9000 n 3 = 1.80518 ν 3 = 25.43 r 4 = -16.4251 d ₄ = 4.0000 r ₅ (aperture diaphragm 13) = ∞ d ₅ = 4.5000

R ₆ = -4.3475 d ₆ = 1.0000 n ₆ = 1.84666 ν ₆ ＝ 23.78 r ₇ ＝ 66.2120 d ₇ ＝ 4.1982 n ₇ = 1.59270 ν ₇ ＝ 35.30 r ₈ ＝ -7.2243 d ₈ ＝ 0.1500 r ₉ ＝ -44.6467 _{d 9 = 2.9000 n 9 = 1.80610} ν 9 = 40.95 r 10 = -10.0511 d 10 = 0.1500

[0047] _{r 11 = 29.7815 d 11 = 4.1000} n 11 = 1.48749 ν 11 = 70.21 r 12 = -9.6246 d 12 = 1.0000 n 12 = 1.80100 ν 12 = 34.97 r 13 = -33.0347 d 13 = 2.0000 r 14 = ∞ d ₁₄ = 5.0000 n ₁₄ = 1.54771 ν ₁₄ = 62.84 r ₁₅ = ∞ d ₁₅ = 2.2400 n ₁₅ = 1.54771 ν ₁₅ = 62.84

R ₁₆ = ∞ d ₁₆ = 10.0000 n ₁₆ = 1.51633 ν ₁₆ = 64.15 r ₁₇ = ∞ d ₁₇ = 3.6100 r ₁₈ = ∞ d ₁₈ = 0.7500 n ₁₈ = 1.48749 ν ₁₈ = 70.21 r ₁₉ = ∞ d ₁₉ = 1.3990 r ₂₀ (CCD 18, 19) = ∞

Third Embodiment FIG. 11 is a diagram showing a cross section perpendicular to the rotation axis of the rotating mirror of the optical system according to the present embodiment. In the optical system of the present embodiment, first, the rotating mirror 1 is sequentially arranged from the object side (not shown).
2. A first lens group 31, which includes a negative meniscus lens 31a having a convex surface facing the rotating mirror 12, a positive lens 31b, and a negative lens 31c and has a negative refracting power as a whole, an aperture stop 13, and a positive lens and a negative lens. Cemented with negative lens 3
The image forming optical system 21 is configured by arranging the second lens group 32 having a positive refracting power as a whole, which is composed of the positive lens 32a and the positive lens 32b. Further, each of the lenses forming the second lens group 32 can be partially or entirely moved on the optical axis L _C. Further, on the exit side of the second lens group 32, an infrared cut filter or a λ / 4 plate 15, an optical low pass filter 16 made of a birefringent plate such as a quartz plate, and a prism 17 made of a beam splitter including a semi-transmissive surface.
Is arranged. CCD 1 in the exit direction of prism 17
8 and 19 are provided, and a cover glass (or a positive lens) 20 is disposed between the prism 17 and the CCD 18 (note that the prism 17 and the CC are not shown).
A similar cover glass or positive lens is also arranged between D19).

The rotation axis of the rotary mirror 12 is in the direction perpendicular to the paper surface, and the extension line of the optical axis L _C of the second lens group 32 is at the position intersecting the mirror surface. The optical low-pass filter 16 is composed of one sheet or a plurality of filters having different crystal axis directions bonded together, and the crystal axis of the filter closest to the prism 17 forms about 45 degrees with respect to the plate surface thereof. As shown in FIG. 12, the orthographic projection of the crystal axis on the plate surface is substantially 45 degrees with respect to the rotation axis of the rotating mirror 12, and the incident light is divided into an ordinary ray and an extraordinary ray and the CCD
It has a function of forming a slightly shifted double image on the surfaces 18 and 19.

The optical system of this embodiment is also designed to photograph the entire object image with two shots (two photographing operations).
The CCD 18 to which the light passing through the prism 17 is incident is arranged so that the long side of its light-receiving surface is perpendicular to the rotating mirror 12, while the CCD 19 has its light-receiving surface oriented accordingly. Therefore, FIG. 13 shows the imaging optical system 2
1 shows the object image formed by No. 1, the upper step A of this object image is taken by the CCD 18 without passing through the prism 17, and the lower step B is the prism 17
It is bent by and is imaged by the CCD 19. The arrow C in the figure indicates the direction of scanning by the rotating mirror 12. In this way, in the optical system of this embodiment, the four images are combined to reproduce the object image.

In the optical system of this embodiment shown in FIG. 11, the rotary mirror 12 is in the standard state at the position indicated by the broken line, and in this state, the optical axis L _C is bent below the 90 ° rotary mirror 12. be able to. Further, the position indicated by the solid line shows the state where the rotating mirror 12 is rotated to the maximum, that is, the state where the chief ray having the maximum image height is rotated by half the angle formed with the optical axis L _C. It is also possible to rotate the rotating mirror 12 in the opposite direction to the illustrated direction.

The following are numerical data of optical elements such as lenses constituting the optical system according to this embodiment. _{d = 20.332mm, n 1 -n 2} = 0.18262 (r 1 + r 2) / (r 1 -r 2) = 0.684

R ₁ = 19.6266 d ₁ = 0.9000 n ₁ = 1.51633 ν ₁ = 64.15 r ₂ = 7.7614 d ₂ = 1.6100 r ₃ = 115.0208 d ₃ = 2.0000 n ₃ = 1.69895 ν ₃ = 30.12 r ₄ = -21.5499 d ₄ = 0.6000 r ₅ = 337.7486 d ₅ = 0.8000 n ₅ = 1.51633 ν ₅ = 64.15

R ₆ = 7.1085 d ₆ = 5.000 r ₇ (aperture diaphragm 13) = ∞ d ₇ = 9.2634 r ₈ = 11.3375 d ₈ = 3.1000 n ₈ = 1.70154 ν ₈ = 41.24 r ₉ = -16.7193 d ₉ = 0.0300 r _{10 = -15.8998 d 10 = 0.9000 n} 10 = 1.80100 ν 10 = 34.97

R ₁₁ = 12.8490 d ₁₁ = 0.8900 r ₁₂ = -137.9874 d ₁₂ = 2.5000 n ₁₂ = 1.65844 v ₁₂ = 50.86 r ₁₃ = -11.5502 d ₁₃ = 2.0000 r ₁₄ = 18.9077 d ₁₄ = 4.4000 n ₁₄ = 1.51742 v _{14 = 52.41 r 15 = -9.8436 d} 15 = 1.0000 n 15 = 1.80518 ν 15 = 25.43

R ₁₆ = -23.9131 d ₁₆ = 2.0000 r ₁₇ = ∞ d ₁₇ = 5.0000 n ₁₇ = 1.54771 ν ₁₇ = 62.84 r ₁₈ = ∞ d ₁₈ = 2.2400 n ₁₈ = 1.54771 ν ₁₈ = 62.84 r ₁₉ = ∞ d ₁₉ = 10.0000 n ₁₉ = 1.51633 ν ₁₉ = 64.15 r ₂₀ = ∞ d ₂₀ = 3.6100

R ₂₁ = ∞ d ₂₁ = 0.7500 n ₂₁ = 1.48749 ν ₂₁ = 70.21 r ₂₂ = ∞ d ₂₂ = 1.4055 r ₂₃ (CCD 18, 19) = ∞

Fourth Embodiment FIG. 14 is a diagram showing a cross section perpendicular to the optical axis of the rotating mirror of the optical system according to the present embodiment. In the optical system of this embodiment,
A first lens group 41 having a negative refracting power as a whole, consisting of a rotary mirror 12, a positive lens 41a and a negative meniscus lens 41b having a convex surface facing the rotary mirror 12 side, an aperture stop 13, and Negative lens 42a
, Positive lens 42b, positive lens 42c, and positive lens 4
The image forming optical system 21 is configured by arranging the second lens group 42 composed of 2d and having a positive refracting power as a whole. Further, among the lenses forming the second lens group 42, the positive lens 42d can move on the optical axis L _C. Further, on the exit side of the second lens group 42, an infrared cut filter or a λ / 4 plate 15, an optical low-pass filter 16 made of a birefringent plate such as a quartz plate, and a prism 17 made of a beam splitter including a semi-transmissive surface. Are arranged. The CCDs 18, 19 are arranged in the exit direction of the prism 17.
Is provided, and a cover glass (or a positive lens) 20 is arranged between the prism 17 and the CCD 18 (note that although not shown, the prism 17 and the CCD 19).
A similar cover glass or positive lens is placed between and).

Further, the rotation axis of the rotary mirror 12 is in the direction perpendicular to the paper surface, and the extension line of the optical axis L _C of the second lens group 42 is at the position intersecting the mirror surface. The optical low-pass filter 16 is composed of one sheet or a plurality of filters having different crystal axis directions bonded together, and the crystal axis of the filter closest to the prism 17 forms about 45 degrees with respect to the plate surface thereof. As shown in 15, the orthographic projection of the crystal axis on the plate surface is substantially 45 degrees with respect to the rotation axis of the rotating mirror 12, and the incident light is divided into an ordinary ray and an extraordinary ray and the CCD
It has a function of forming a slightly shifted double image on the surfaces 18 and 19.

The optical system of this embodiment is also designed to photograph the entire object image in two shots (two photographing operations).
The CCD 18 to which the light passing through the prism 17 is incident is arranged so that the long side of its light-receiving surface is perpendicular to the rotating mirror 12, while the CCD 19 has its light-receiving surface oriented accordingly. Therefore, FIG. 16 shows the imaging optical system 2
1 shows the object image formed by No. 1, the upper step A of this object image is taken by the CCD 18 without passing through the prism 17, and the lower step B is the prism 17
It is bent by and is imaged by the CCD 19. The arrow C in the figure indicates the direction of scanning by the rotating mirror 12. In this way, in the optical system of this embodiment, the four images are combined to reproduce the object image.

In the optical system of the present embodiment shown in FIG. 14, the rotary mirror 12 is in the standard state at the position indicated by the broken line, and in this state the optical axis L _C is bent below the 90 ° rotary mirror 12. be able to. The position indicated by the solid line shows the state in which the rotating mirror 12 is rotated to the maximum, and is the state in which the chief ray having the maximum image height is rotated by half the angle formed by the optical axis L _C. The rotating mirror 12 can of course be rotated in the opposite direction to the illustrated direction.

The following are numerical data of optical elements such as lenses constituting the optical system according to the present embodiment. _{d = 14.771mm, n 1 -n 2} = 0.33033 (r 1 + r 2) / (r 1 -r 2) = - 1.142

R ₁ = 19.7495 d ₁ = 2.2000 n ₁ = 1.84666 v ₁ = 23.78 r ₂ = 298.3938 d ₂ = 0.6000 r ₃ = 47.3674 d ₃ = 0.9000 n ₃ = 1.51633 v ₃ = 64.15 r ₄ = 4.9415 d ₄ = 4.5000 r ₅ (aperture stop 13) = ∞ d ₅ = 6.5000

R ₆ = 15.1388 d ₆ = 0.9000 n ₆ = 1.84666 ν ₆ ＝ 23.78 r ₇ ＝ 104.4931 d ₇ ＝ 0.2500 r ₈ ＝ -36.0058 d ₈ ＝ 2.2000 n ₈ = 1.56873 ν ₈ ＝ 63.16 r ₉ ＝ -10.4558 d ₉ = 0.1500 r ₁₀ = 107.1696 d ₁₀ = 3.1000 n ₁₀ = 1.56873 ν ₁₀ = 63.16

R ₁₁ = -11.4135 d ₁₁ = 1.6000 r ₁₂ = 30.9530 d ₁₂ = 2.3000 n ₁₂ = 1.51633 ν ₁₂ = 64.15 r ₁₃ = -44.2824 d ₁₃ = 2.0000 r ₁₄ = ∞ d ₁₄ = 5.0000 n ₁₄ = 1.54771 ν ₁₄ = 62.84 r ₁₅ = ∞ d ₁₅ = 1.6000 n ₁₅ = 1.51633 ν ₁₅ = 64.15

R ₁₆ = ∞ d ₁₆ = 2.2400 n ₁₆ = 1.54771 ν ₁₆ = 62.84 r ₁₇ = ∞ d ₁₇ = 13.0000 n ₁₇ = 1.51633 ν ₁₇ = 64.15 r ₁₈ = ∞ d ₁₈ = 1.5000 r ₁₉ = ∞ d ₁₉ = _{0.7500 n 19 = 1.48749 ν 19 =} 70.21 r 20 = ∞ d 20 = 1.3953 r 21 (CCD18,19) = ∞

However, in each of the above embodiments, r₁,
r₂, ... is the radius of curvature of the optical element surface such as a lens, d
₁, D₂, ... is the thickness of each optical element or
Interval, n ₁, N₂, ... is the refractive index of each optical element, ν
₁, Ν₂, ... Show the Abbe number of each optical element
ing.

As described above, the optical system for the electronic image pickup device having the mirror scan function according to the present invention is
Combined with the features described in claims 1 to 4, the following (1) to
It also has the features shown in (9).

(1) In order from the object side, a first lens unit consisting of two lenses, a negative lens and a positive lens, having a negative refracting power as a whole and a rotatable lens for bending the optical axis from the object point An imaging optical system including a mirror, an aperture stop, and a second lens group having a positive refracting power that can be partially or wholly moved along the optical axis, and an electronic imaging device that receives light that has passed through the imaging optical system. An optical system for an electronic image pickup device having a mirror scan function, characterized in that the following conditional expressions are satisfied at the same time. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 2 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <10 where d is the center position of rotation of the rotatable mirror. And the distance from the position to the pupil position of the imaging optical system viewed from this position, n ₁
Is the refractive index of the positive lens arranged closest to the object side, n ₂
Is the refractive index of the negative lens arranged closest to the object side,
r ₁ and r ₂ indicate the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively.

(2) In order from the object side, the first lens group having negative refracting power, the rotatable mirror for bending the optical axis from the object point, the second lens group having positive refracting power, and the aperture stop. An imaging optical system including a third lens group having a positive refracting power that is partially or wholly movable along the optical axis, and an electronic imaging device that receives light that has passed through the imaging optical system. An optical system for an electronic image pickup device having a mirror scan function, characterized in that the following conditional expressions are simultaneously satisfied. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 1 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <3 where d is the center position of rotation of the rotatable mirror. And the distance from the position to the pupil position of the imaging optical system viewed from this position, n ₁
Is the refractive index of the positive lens arranged closest to the object side, n ₂
Is the refractive index of the negative lens arranged closest to the object side,
r ₁ and r ₂ indicate the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively.

(3) In order from the object side, a rotatable mirror for bending the optical axis from the object point, two or less negative lenses and one positive lens, and having a negative refracting power as a whole. An image-forming optical system including one lens group, an aperture stop, and a second lens group having a positive refracting power capable of moving partly or wholly along the optical axis, and an electron for receiving light passing through this image-forming optical system. An optical system for an electronic image pickup apparatus having a mirror scan function, wherein an image pickup device and an image pickup device are arranged to satisfy the following conditional expressions at the same time. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 −1 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <1, where d is the center of rotation of the rotatable mirror The distance between the position and the pupil position of the imaging optical system viewed from this position, n ₁
Is the refractive index of the positive lens arranged closest to the object side, n ₂
Is the refractive index of the negative lens arranged closest to the object side,
r ₁ and r ₂ indicate the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively.

(4) In order from the object side, a rotatable mirror for bending the optical axis from the object point, a positive lens, and a negative meniscus lens having a convex surface facing the object side have a negative refracting power as a whole. Image formation including a first lens group, an aperture stop, a negative lens, and three positive lenses, and a positive lens closest to the image side is movable on the optical axis and has a positive refractive power as a whole. An electronic device having a mirror scan function, which is configured by arranging an optical system and an electronic image pickup device that receives light that has passed through the imaging optical system, and simultaneously satisfies the conditional expressions shown below. Optical system for imaging device. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 −3 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <0 where d is the center of rotation of the rotatable mirror The distance between the position and the pupil position of the imaging optical system viewed from this position, n ₁
Is the refractive index of the positive lens arranged closest to the object side, n ₂
Is the refractive index of the negative lens arranged closest to the object side,
r ₁ and r ₂ indicate the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively.

(5) A semi-transparent mirror is provided between the image forming optical system and the electronic image pickup device to divide light into a direction in which an optical axis is bent and a direction in which light passes through. 2 and an optical system for an electronic imaging device having a mirror scan function according to any one of (1) to (4) above.

(6) The long side direction of the electronic image pickup device is aligned substantially parallel to the rotation axis of the rotatable mirror, and the bending direction of the optical axis by the semi-transparent mirror is rotated by the rotatable mirror. An optical system for an electronic image pickup device having a mirror scan function according to claim 3, wherein the optical system is perpendicular to the axis.

(7) The long side direction of the electronic image pickup device is aligned with the direction substantially perpendicular to the rotation axis of the rotatable mirror, and the bending direction of the optical axis by the semi-transparent mirror is rotated by the rotatable mirror. The optical system for an electronic image pickup device having a mirror scan function according to claim 4, wherein the optical system is arranged in a direction parallel to the axis.

(8) An optical low-pass filter utilizing the birefringence of a crystal is arranged between the image-forming optical system and the semi-transparent mirror, or (1) to (4) or (1) above. An optical system for an electronic imaging device having a mirror scan function according to any one of (1) to (7).

(9) Among the optical low-pass filters, the azimuth of the orthogonal projection image of the crystal axis of the filter arranged at the position closest to the semi-transparent mirror on the image plane of the image-forming optical system is the rotation. 40 to 50 with respect to the possible rotation axis of the mirror
An optical system for an electronic image pickup device having a mirror scan function according to the above (8), which is characterized in that

[0079]

As described above, according to the present invention, the conventional CC having a small number of pixels and a small effective imaging area is used.
It is possible to easily obtain a high-definition image having a number of pixels equal to or higher than the HDTV standard and a silver salt level while using an inexpensive and small-sized optical system having the performance and size corresponding to D. This makes it possible to easily capture fine characters and patterns, which was not possible with conventional simple electronic imaging devices.
An image input device of an information processing system with good operability can be realized. Then, in the apparatus having such a mirror scan function, the parallax during scanning that occurs when the conventional imaging optical system is used can be eliminated by using the optical system of the present invention.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical system for an electronic image pickup apparatus having a mirror scan function according to the present invention.

FIG. 2 is a CCD used in the optical system according to the present invention.
3 is a diagram for explaining the arrangement configuration of FIG.

FIG. 3 is a lens configuration diagram of an optical system of the present invention, (a)
Is a cross-sectional view taken along the optical axis of the optical system, (b) is a view showing a cross section of a plane including the rotation axis of the rotating mirror seen from above, and (c) is a cross section perpendicular to the rotation axis of the rotating mirror seen from the side. FIG.

FIG. 4 is a CC of an object image formed by the optical system of the present invention.
It is a figure for demonstrating the imaging state in D.

FIG. 5 is a diagram showing a cross section perpendicular to the rotation axis of the rotating mirror of the optical system according to the first example of the present invention.

FIG. 6 is a diagram for explaining the azimuths of the orthogonal projection of the crystal axis of the optical low-pass filter used in the optical system of the first embodiment on the plate surface and the rotation axis of the rotating mirror.

FIG. 7 is a diagram for explaining an image pickup state by a CCD of an object image formed by the optical system of the first embodiment.

FIG. 8 is a view showing a cross section perpendicular to a rotation axis of a rotating mirror of an optical system according to a second example.

FIG. 9 is a diagram for explaining the azimuths of the orthogonal projection of the crystal axis of the optical low-pass filter used in the optical system of the second embodiment on the plate surface and the rotation axis of the rotating mirror.

FIG. 10 is a diagram for explaining an image pickup state by a CCD of an object image formed by the optical system of the second embodiment.

FIG. 11 is a diagram showing a cross section perpendicular to a rotation axis of a rotating mirror of an optical system according to a third example.

FIG. 12 is a diagram for explaining the azimuths of the orthogonal projection of the crystal axis of the optical low-pass filter used in the optical system of the third example on the plate surface and the rotation axis of the rotating mirror.

FIG. 13 is a diagram for explaining an image pickup state by a CCD of an object image formed by the optical system of the third example.

FIG. 14 is a diagram showing a cross section perpendicular to a rotation axis of a rotating mirror of an optical system according to a fourth example.

FIG. 15 is a diagram for explaining the azimuths of the orthogonal projection of the crystal axis of the optical low-pass filter used in the optical system of the fourth example on the plate surface and the rotation axis of the rotating mirror.

FIG. 16 is a diagram for explaining an image pickup state by a CCD of an object image formed by the optical system of the fourth example.

[Explanation of symbols]

1,12 Rotating mirror 2,13 Aperture stop 3,14,23,32,42 Second lens group 4,16 Optical low-pass filter 5,17 Semi-transparent mirror (prism) 6,7,18,19 CCD 8,9, 14c, 24b, 31b, 32b, 41a, 4
2b, 42c Positive lens 10, 21 Imaging optical system 11, 22, 31, 41 First lens group 11a, 31a, 41b Negative meniscus lens 11b, 31c Positive meniscus lens 14a, 14b, 14d, 24c, 32c Bonded positive lens 24a , 32a, 42a cemented negative lens 15 infrared cut filter 20 cover glass 24 third lens group

Claims (4)

[Claims] 1. A first lens group having a negative refractive power and including a negative lens closest to the object side in order from the object side, a rotatable mirror for bending an optical axis from an object point, an aperture stop, and an optical axis. An imaging optical system including a second lens group having a positive refracting power that can be partially or wholly moved above, and an electronic device that receives light transmitted through the imaging optical system are arranged and configured. An optical system for an electronic image pickup device having a mirror scan function, characterized in that the following conditional expressions are satisfied at the same time. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 2 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <10 where d is the rotation center position of the rotatable mirror. The distance from the position to the pupil position of the imaging optical system viewed from the position, n ₁ is the refractive index of the positive lens arranged closest to the object, and n ₂ is the refractive index of the negative lens arranged closest to the object. , R ₁ , r
₂ indicates the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively. 2. A rotatable mirror for bending an optical axis from an object point, a first lens group having negative refractive power and including a positive lens closest to the object side, an aperture stop, and an optical axis in order from the object side. An imaging optical system including a second lens group having a positive refracting power that can be partially or wholly moved above, and an electronic device that receives light transmitted through the imaging optical system are arranged and configured. An optical system for an electronic image pickup device having a mirror scan function, characterized in that the following conditional expressions are satisfied at the same time. 7 mm <d <25 mm 0.1 <n ₁ −n ₂ <0.4 −3 <(r ₁ + r ₂ ) / (r ₁ −r ₂ ) <1, where d is the rotation center position of the rotatable mirror. And the distance from the position to the pupil position of the imaging optical system viewed from that position, n ₁ is the refractive index of the positive lens arranged closest to the object, and n ₂ is the refraction of the negative lens arranged closest to the object. Rate, r ₁ , r
₂ indicates the object-side and image-side radii of curvature of the positive lens disposed closest to the object side, respectively. 3. A semi-transparent mirror that splits light between a direction in which the optical axis is bent and a transparent direction, between an electronic imaging device and an imaging optical system including a rotatable mirror for bending the optical axis from an object point. In an optical system for an electronic image pickup device having a mirror scan function, the number of shots is 3 when a plurality of shots are performed through the mirror scan and each image is electrically bonded to form one screen. In the case of more than one rotation, the long side direction of the electronic image pickup device is aligned with the direction substantially parallel to the rotation axis of the rotatable mirror, and the bending direction of the optical axis by the semi-transparent mirror can be rotated. An optical system for an electronic image pickup device having a mirror scanning function, characterized in that it is arranged in a direction perpendicular to the rotation axis of the mirror. 4. A semi-transparent mirror that divides light into a direction in which the optical axis is bent and a direction in which the light is passed through, between an electronic imaging device and an imaging optical system that includes a rotatable mirror for bending the optical axis from an object point. In an optical system for an electronic image pickup device having a mirror scan function, the number of shots is 3 when a plurality of shots are performed through the mirror scan and each image is electrically bonded to form one screen. When the number of rotations is less than or equal to the number of rotations, the long side direction of the electronic image pickup device is aligned with the direction substantially perpendicular to the rotation axis of the rotatable mirror, and the bending direction of the optical axis by the semi-transparent mirror can be rotated. An optical system for an electronic image pickup device having a mirror scanning function, wherein the optical system is arranged in a direction parallel to the rotation axis of the mirror.