JP3370568B2 - Anti-vibration lens attachment - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a CCTV (surveillance camera), for example.
Anti-vibration lens attachment used for.

[0002]

2. Description of the Related Art An anti-vibration lens that absorbs vibration applied to a taking lens system and forms an image on an image forming surface (imaging surface) of a camera body is conventionally one of the taking lens system (master lens) itself. An integral type that has a correction lens group that is movable in the direction orthogonal to the optical axis in its part, and an attachment that attaches to and detaches between the taking lens system and the camera body, and that supports the anti-vibration lens system including the correction lens group. The type is known. In both types, the vibration applied to the camera is detected, and the correction lens group is driven in the direction orthogonal to the optical axis according to the magnitude and direction of the vibration, thereby reducing the image blur on the image plane. Various types of vibration detection means and drive mechanisms for anti-vibration lenses have already been known and put into practical use.

In the latter attachment type, conventionally, an anti-vibration lens system including a correction lens group is arranged between a taking lens system (master lens) and its image plane. In other words, insert the anti-vibration lens system before focusing with the shooting lens system,
An image is formed on the image forming surface of the camera body by shifting the image forming position rearward by an amount corresponding to the thickness of the attachment (dimension between mounts).

It is desired that the focal length of the master lens should not be largely changed (that is, the magnification should be in the vicinity of unity magnification) as the image stabilization lens attachment, but in the conventional image stabilization lens attachment, the magnification should be set in the vicinity of unity magnification. When I did
It is difficult to secure the thickness of the attachment, and therefore, the number of constituent lenses of the image stabilizing lens system is set to a number sufficient to correct various aberrations, or the correction lens group is driven in the direction orthogonal to the optical axis. It was difficult to store the drive mechanism and the like.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to increase the degree of freedom in the construction of an anti-vibration lens system, to set the magnification arbitrarily, and to ensure a sufficient thickness for accommodating the drive mechanism of the correction lens group. The purpose is to obtain a lens attachment.

[0006]

SUMMARY OF THE INVENTION According to the present invention, if an image is formed by a taking lens system and then this image is relayed to an image forming surface of a camera body by a vibration proof lens system, the magnification can be arbitrarily set and the thickness of the attachment can be set. This was done focusing on the fact that the size can be increased.

That is, the present invention has an anti-vibration lens system including at least one correction lens group that is movable in a direction orthogonal to the optical axis, and is attachable / detachable between the taking lens system and the camera body. In the attachment, the anti-vibration lens system including the correction lens group is provided at a position where the image formed by the taking lens system is inverted at least once and re-imaged on the image formation surface of the camera body.

According to another expression, the present invention has an anti-vibration lens system including at least one correction lens group which is movable in a direction orthogonal to the optical axis, and is provided between the taking lens system and the camera body. In the removable anti-vibration lens attachment, the magnification m of the anti-vibration lens system including the correction lens group is m
It is characterized by being <0. m <0 means that
It means that the direction of the image is reversed once. Although it is not impossible to invert the image direction more than once (m> 0 when the image inversion is an even number), it is preferable to invert the image once from the viewpoint of size and performance.

[0009] anti-vibration lens system that consists in a direction perpendicular to the optical axis by a correction lens group movable also perpendicular to the optical axis
It may be composed of a correcting lens group and the stationary lens group movable in the direction. The magnification m of this anti-vibration lens system is
Considering the screen size of the imaging surface of the shooting lens system and the screen size of the imaging surface of the anti-vibration lens attachment,
Within the range of the operation amount of the correction lens group, it is preferable that the anti-vibration lens system is set to always relay the image within the screen size of the taking lens system within the screen size of the camera body.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a vibration-proof lens attachment 10 according to the present invention mounted between a taking lens system (master lens) 20 and a CCTV camera body 30. Anti-vibration lens attachment 10
Having a lens mount MT _M for mounting a taking lens system 20 at its front end, it has a body mount MT _A to bind to the camera body 30 to the rear end.

In the vibration-proof lens attachment 10, a correction lens group 11 that is movable in a direction orthogonal to the optical axis and a fixed lens group that is fixed are provided behind the image-forming position F _{M formed} by the taking lens system 20. An anti-vibration lens system (relay lens system) 13 including 12 is arranged. This anti-vibration lens system 13 is a photographing lens system 2 that forms an image at the image formation position F _M.
The image of 0 is formed on the image plane 31 (CCD) of the camera body 30.
The image is re-imaged (relayed) on 31, and the vibration proof lens system as a whole can have an afocal system or positive or negative power. Since it is desired that the correction lens group is light in view of the mechanical structure, it is preferable that the image stabilizing lens system 13 is composed of the movable correcting lens group 11 and the fixed lens group 12. The entire correction lens group 11 may be movable in a direction orthogonal to the optical axis. The order of the movable correction lens group 11 and the fixed lens group 12 may be reversed.

FIG. 2 shows a taking lens system 20 for comparison.
An example of a conventional anti-vibration lens attachment 10 'in which an anti-vibration lens system 13' is arranged between the image pickup position F _M and the imaging position F _M by the taking lens system 20 is shown. In the conventional example shown in FIG. 2, the anti-vibration lens system 13 'functions to shift the imaging position of the taking lens system 20 backward by an amount corresponding to the thickness of the anti-vibration lens attachment 10'. However, there is a limit to shifting the image forming position rearward, and thus it has been difficult to increase the thickness of the vibration-proof lens attachment 10 '(dimension between mounts). That is, the dimension L between mounts
Is L = (m−1) a + Δ (m; magnification, a; distance from the first principal point of the attachment to the image plane of the master lens,
Δ: Principal point spacing of the image stabilizing lens system 13 ′). Therefore, when the magnification is about the same size (m≈ + 1), the conventional image stabilizing lens system 13 ′ has a small principal point distance Δ, and thus the image stabilizing attachment It was difficult to increase the thickness.

On the other hand, according to the embodiment of the present invention shown in FIG. 1, the anti-vibration lens system 13 forms an image formed by the taking lens system 20 at the image forming position F _M on the image forming surface 3 of the camera body 30.
Since it is relayed to 1, it is possible to easily thicken the vibration-proof lens attachment 10 (longer the length in the optical axis direction),
Therefore, the degree of freedom of the lens configuration of the image stabilizing lens system 13 is increased, and the drive mechanism for driving the correction lens group 11 can be easily housed.

The magnification m of the anti-vibration lens system 13 of the anti-vibration lens attachment 10 is preferably set as follows. In FIGS. 3 and below, the image stabilizing lens system 13 is depicted as a single correction lens group 11.

3 and 4, the screen size Y _M of the taking lens system 20 and the screen size Y _A of the anti-vibration lens attachment 10 are equal, and the magnification m of the anti-vibration lens system 13 is
The case where | m | = 1 is shown. I _M represents the size of the master image plane that is conjugate with the screen size Y _A of the image plane 31. F _A is an image forming position by the correction lens group 11. In the case of FIG. 3 and FIG. 4, when the correction lens group 11 is not operated, all the images on the screen size Y _M by the taking lens system 20 are displayed on the screen size Y of the image stabilizing lens attachment 10 as shown in FIG. _Although it can be relayed to _A , when the correction lens group 11 moves in the direction orthogonal to the optical axis, the correction lens group 11 displays the screen size Y _M as shown in FIG.
The area S other than the area S is relayed to the screen size Y _A, which causes deterioration of image performance and reduction of light quantity, which is not preferable.

On the other hand, in FIGS. 5 and 6, the same Y _M = Y
Under the condition of _A , | m |> 1 is set, and within the range of the operation amount of the correction lens group 11, the correction lens group 11 constantly displays an image within the screen size Y _M of the taking lens system 20 with the image stabilization lens attachment 10 This is an example of setting to relay within the screen size Y _{A of} . That is, Y _M > I _M.

Further, FIGS. 7 and 8 show the case where Y _M > Y _A. In this case, the conditions to ensure the margin of the screen _{size, I M <Y M, |} m | = Y A / from the I _M, Y _A /
Since Y _M <| m |, | m | can be set to 1 (equal magnification) or a value smaller than 1. Therefore, the correction lens group 11 is always used for the screen size Y _{M of the} taking lens system 20.
The image inside is the screen size Y of the anti-vibration lens attachment 10.
Can be configured to relay into _A. vice versa,
When Y _M <Y _A is, | m | is greater than 1 Y _A / Y
_The value must exceed _M.

As described above, the specific mechanism for driving the correction lens group 11 of the image stabilizing lens system 13 in the direction orthogonal to the optical axis, the element for detecting the vibration applied to the camera, the mechanism, and the detected vibration. Accordingly, an algorithm or the like for driving the correction lens group 11 has already been known, and the present invention does not require any of these mechanisms.

[0019]

According to the present invention, it is possible to increase the thickness of the antivibration lens attachment mounted between the taking lens system and the camera body, and thus the freedom of design of the antivibration lens system is increased. As a result, the magnification can be increased and the magnification can be set arbitrarily, and the drive mechanism for the correction lens group can be easily housed.

[Brief description of drawings]

FIG. 1 is a conceptual diagram showing an embodiment of a vibration proof lens attachment according to the present invention in a state where the lens attachment is mounted between a taking lens system and a camera body.

FIG. 2 is a conceptual diagram corresponding to FIG. 1, showing an example of a conventional anti-vibration lens attachment for comparison.

FIG. 3 is a diagram showing an example of the relationship between the screen size of the taking lens system, the screen size of the camera body, and the magnification of the image stabilizing lens system of the image stabilizing lens attachment when the correction lens group is not operating. Is.

FIG. 4 is a diagram showing a state when the image stabilizing lens operates in FIG. 3;

FIG. 5 shows another example of the relationship between the screen size of the taking lens system, the screen size of the camera body, and the magnification of the anti-vibration lens system of the anti-vibration lens attachment. FIG.

FIG. 6 is a diagram showing a state when the image stabilizing lens in FIG. 5 is activated.

FIG. 7 shows another example of the relationship between the screen size of the taking lens system, the screen size of the camera body, and the magnification of the anti-vibration lens system of the anti-vibration lens attachment when the correction lens group is not in operation. FIG.

8 is a diagram showing a state when the image stabilizing lens operates in FIG. 7. FIG.

[Explanation of symbols]

10 Anti-vibration lens attachment 11 Correction lens group 12 fixed lens group 13 Anti-vibration lens system 20 Shooting lens system (master lens) 30 camera body 31 Image plane (CCD)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP 63-201624 (JP, A) JP 5-196982 (JP, A) JP 54-73025 (JP, A) JP 62- 273506 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) G03B 5/00 G02B 7/02 G02B 15/10 G02B 27/64 G03B 17/12

Claims (7)

(57) [Claims] 1. An anti-vibration lens attachment which has a vibration-proof lens system including at least one correction lens group movable in a direction orthogonal to an optical axis, and which is detachable between a photographing lens system and a camera body, An anti-vibration lens system including the above-mentioned correction lens group is provided at a position where an image formed by the taking lens system is inverted at least once and re-imaged on the imaging surface of the camera body. attachment. 2. The antivibration lens attachment according to claim 1, wherein the antivibration lens system includes only a correction lens group movable in a direction orthogonal to the optical axis. 3. The anti-vibration lens attachment according to claim 1, wherein the anti-vibration lens system includes a correction lens group that is movable in a direction orthogonal to the optical axis and a stationary lens group that does not move. . 4. The image stabilizing lens attachment according to claim 1, wherein the magnification m of the image stabilizing lens system is the screen size on the image plane of the taking lens system,
Taking into account the screen size of the image plane of the anti-vibration lens attachment, the anti-vibration lens system will always take an image within the screen size of the lens system within the screen size of the camera body within the range of the movement amount of the correction lens group. Anti-vibration lens attachment that is set to relay. 5. An anti-vibration lens attachment, which has an anti-vibration lens system including at least one correction lens group movable in a direction orthogonal to an optical axis, and is attachable / detachable between a taking lens system and a camera body, The magnification m of the entire image stabilizing lens system including the correction lens group is
Anti-vibration lens attachment characterized by m <0. 6. The anti-vibration lens attachment according to claim 5, wherein the magnification m of the anti-vibration lens system is the screen size of the imaging surface of the taking lens system and the screen size of the imaging surface of the anti-vibration lens attachment. Considering this, within the range of movement of the correction lens group, the anti-vibration lens system is set so that the image within the screen size of the shooting lens system is always relayed within the screen size of the camera body. . 7. The antivibration lens attachment according to claim 5, wherein when the taking lens system and the antivibration lens attachment have the same screen size, 1 <| m | is satisfied.