JPH0743592A - Photographic lens optical system and liquid prism - Google Patents

Abstract

PURPOSE:To provide the photographic lens optical system which can be focused by a simple mechanism and the liquid prism adaptive to the photographic lens optical system. CONSTITUTION:A high voltage is applied to a piezo element 32 of the liquid prism 12 to extend a flexible cylinder 26 toward an optical axis 14 and to prolong the distance between a front glass plate 18 and a rear glass plate 30 in the case of focusing by extending a variable lens and a compensator lens to a telephoto side. Therefor, the exit light from a master lens is polarized by water 34 filled in the flexible cylinder 26 and is extended in its optical path length when this exit light is made incident on the front glass plate 28 of the liquid prism. This polarized light is emitted from the rear glass plate 30 at the same angle as the exit angle from the master lens and is focused on the image forming surface of a CCD. On the other hand, the focusing on a wide side is executed simply by applying a low voltage to the piezo element 32 to reduce the flexible cylinder 26 in the optical axis direction and shortening the distance between the front glass plate 28 and the gear glass plate 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a taking lens optical system and a liquid prism, and more particularly to a taking lens optical system of a camera having a focus adjusting function, and a liquid prism applicable to the taking lens optical system. Regarding

[0002]

2. Description of the Related Art FIG. 14 is a side view showing a general structure of a conventional taking lens optical system 1 having a focus adjusting function and a magnification changing function. In this photographing lens optical system 1, a focus lens 3, a variator lens 4, a compensator lens 5, and a master lens 6 are arranged in this order from the front along an optical axis 2, and the variator lens 4 and the compensator lens 5 are connected to the optical axis 2 Magnification is performed by moving the CCD back and forth along the image plane 7 of the CCD 7.
The focus shift on A is corrected by moving the focus lens 3 back and forth along the optical axis 2.

[0003]

As described above, since the conventional taking lens optical system 1 moves the focus lens 3 to perform focusing, an error occurs in the movement amount of the focus lens 3 or the focus lens 3 moves. If the center axis of the lens 3 is tilted or decentered with respect to the optical axis 2, not only the focusing but also the optical performance (one-sided blur, reduced resolution, image distortion) will be greatly affected. There is.

As a result, in the conventional photographic lens optical system 1, the complex moving mechanism of the focus lens 3 must be manufactured and assembled with high precision, which has a disadvantage of significantly increasing the cost. The present invention has been made in view of such circumstances, and an object thereof is to provide a photographic lens optical system capable of performing focusing with a simple mechanism, and to be adapted to this photographic lens optical system. An object of the present invention is to provide a liquid prism that can be used.

[0005]

In order to achieve the above-mentioned object, the first invention of the present invention is such that a transparent plate is fixed to the front end portion and the rear end portion, and the inside is expandable and contractible with a transparent liquid. A flexible cylinder and a drive means for expanding and contracting the flexible cylinder, the liquid prism is arranged on the optical axis of a photographing lens, and the flexible cylinder is expanded and contracted by the drive means. Then, the focus is adjusted by changing the optical path length passing through the liquid.

In order to achieve the above-mentioned object, the second invention of the present invention is such that at least one of the transparent plates fixed to the front end and the rear end is provided via an elastic member and is internally provided. A container filled with a transparent liquid, and a heater provided on the inner wall of the container, and a liquid prism having a liquid prism, the liquid prism is arranged on the optical axis of the photographing lens,
By heating the liquid by the heater to expand the liquid in the container, the elastic member is elastically deformed to widen the distance between the transparent plates and change the optical path length passing through the liquid. Therefore, it is characterized in that the focus is adjusted.

According to a third aspect of the present invention, in order to achieve the above object, transparent plates are fixed to the front end and the rear end, and
It is characterized by comprising an expandable and contractible flexible cylinder filled with a transparent liquid and a drive means for expanding and contracting the flexible cylinder.

[0008]

According to the first photographing lens optical system of the present invention, the liquid prism is arranged in the image pickup device instead of the focus lens, and the driving means of the liquid prism is driven to make the flexible liquid filled with the transparent liquid. Focusing is performed by expanding and contracting the tube in the optical axis direction, expanding and contracting the distance between the transparent plates, and varying the optical path length passing through the liquid.

According to the second taking lens optical system of the present invention, the liquid prism is arranged in the image pickup device instead of the focus lens, and the heater of the liquid prism is operated to expand the transparent liquid filled in the container. By doing so, the elastic member is elastically deformed to widen the distance between the transparent plates, and the optical path length passing through the liquid is varied to perform focus adjustment. According to the first liquid prism of the present invention, by driving the driving means, the flexible cylinder filled with the transparent liquid is expanded and contracted, and the transparent plate fixed to the front end and the rear end of the flexible cylinder is provided. Scale the distance of. As a result, the optical path length passing through the liquid is changed, and by adjusting the variable amount, the light can be polarized in a desired direction.

[0010]

The preferred embodiments of the taking lens optical system and the liquid prism according to the present invention will be described in detail below with reference to the accompanying drawings. 1 is a side view showing an embodiment of a taking lens optical system 10 according to the present invention, FIG. 2 is a plan view of a liquid prism 12 applied to the taking lens optical system 10, and FIG. 3 is a sectional view of the liquid prism 12. Is.

In the taking lens optical system 10 shown in FIG. 1, a front lens 16, a variator lens 18, a compensator lens 20, a master lens 22 and a liquid prism 12 are arranged in this order from the front along an optical axis 14, and the variator lens is used. 18 and the compensator lens 20 are moved back and forth along the optical axis 14 to change the magnification, and the image plane 2 of the CCD 24 caused by the distance to the object.
The shift of the focus on 4A is corrected by driving the liquid prism 12 described later.

As shown in FIGS. 2 and 3, the liquid prism 12 comprises a bellows-shaped flexible tube 26, a front glass plate 28, a rear glass plate 30, and a piezo element 32 which is a drive section. The upper end of the flexible tube 26 in FIG. 3, that is, the front end of the optical axis 14 is fixed to the front glass plate 28, and the rear end of the optical axis 14 is fixed to the rear glass plate 30. To be done. A transparent liquid (water) 34 is sealed and filled in the flexible cylinder 26 by the front glass plate 28 and the rear glass plate 30.

The front glass plate 28 and the rear glass plate 30 are fixed to frame plates 36 and 38 formed in a donut shape, respectively. The frame plate 38 has two guide bars 4
0 and 42 are erected on the frame plate 36. A guide cylinder 44 integrally formed with the frame plate 36 is slidably provided at the base end portion of the guide rod 40 via the piezoelectric element 32. Further, the upper end portion of the guide rod 42 is in sliding contact with the guide groove 46 formed in the frame plate 36.

The piezo element 32 is connected to the battery of the camera through a transformer (not shown), and the voltage from the battery is transformed by the transformer and applied. If the applied voltage is low, the piezoelectric element 32 is expanded. When the amount is small and the voltage is high, the expansion is large and the state expands to the state shown in FIG.
As a result, in the flexible cylinder 26, the expansion and contraction operation of the piezo element 32 described above causes the guide cylinder 44, the frame plate 36, and the front glass plate 2 to move.
8 is transmitted via the guide rods 40 and 42, so that it is expanded and contracted along the guide rods 40 and 42 in the optical axis 14 direction.

Next, the operation of the taking lens optical system 10 will be described. For example, when focusing on a distant subject, since the focus of light is located closer to the master lens 22 side than the near subject, a high voltage can be applied to the piezo element 32 shown in FIG. The flexible cylinder 26 is extended in the optical axis 14 direction as shown in FIG. 4, and the distance between the front glass plate 28 and the rear glass plate 30 is set to l ₁ . As a result, the light 48 emitted from the master lens 22 is emitted from the liquid prism 12
When the light enters the front glass plate 28, it is refracted by the water 34 filled in the flexible tube 26, that is, the optical path length is extended by l ₁ , and then the exit angle from the rear glass plate 30 from the master lens 22. The light is emitted at the same angle as and is focused on the image plane 24A of the CCD 24.

On the other hand, when focusing on a near object, since the focal point of light is located closer to the CCD 24 than the far object, a low voltage is applied to the piezo element 32 shown in FIG. The flexible tube 26 is slightly extended in the direction of the optical axis 14 as shown in FIG. 5, and the distance between the front glass plate 28 and the rear glass plate 30 is set to l ₂ (l ₁ > l ₂ ). This allows
When the outgoing light 48 from the master lens 22 enters the front glass plate 28 of the liquid prism 12, it is refracted into the water 34 in the flexible tube 26, that is, the optical path length is extended by l ₂ and then the rear glass. The light is emitted from the plate 30 and focused on the image plane 24A of the CCD 24.

As described above, in this embodiment, the liquid prism 12 is arranged instead of the focus lens, the piezo element 32 of the liquid prism 12 is driven, and the flexible cylinder 26 is expanded and contracted to form the front glass plate 28. The distance from the rear glass plate 30 was expanded / contracted, and the optical path length passing through the water 34 was varied to adjust the focus. That is, in the present embodiment, by adapting the liquid prism 12 having a power lower than that of the lens, even if some error occurs in the expansion and contraction amount of the flexible tube 26, it does not hinder focusing, and Even if the central axis of the liquid prism 12 is tilted or decentered with respect to the optical axis 12 of the imaging device 10, the optical performance is not deteriorated. Therefore, focusing can be performed with a simple mechanism.

FIG. 6 is a cross-sectional view of an essential part showing a second embodiment of the liquid prism 12A, and a piezo element 32 as a driving part.
The cam cylinder 50 is used instead of. The cam barrel 50 is rotatably inserted through the guide rod 40, and the guide barrel 44 is in contact with the spiral cam portion 52 shown in FIG. 7 formed at the upper end of the cam barrel 50. Also, the cam barrel 5
A gear 54 is threaded on the lower end of 0, and this gear 54 is meshed with a gear 58 of a motor 56 as shown in FIG. Therefore, when the motor 56 is driven, the cam barrel 50 rotates with respect to the guide rod 40, so that the guide barrel 44 moves up and down along the cam portion 52 as indicated by the arrow.

As a result, even when the cam barrel 50 is used as the drive unit of the liquid prism, the flexible barrel 26 can be expanded and contracted along the optical axis, and the same effect as the liquid prism 12 using the piezo element 32 can be obtained. be able to. FIG. 8 is a cross-sectional view showing a third embodiment of the liquid prism 60 according to the present invention, and the same or similar members as those of the first embodiment shown in FIG. Is omitted.

The liquid prism 60 shown in the figure is constructed such that the front glass plate 28 is provided on the upper portion of the cylindrical container 62, and the rear glass plate 30 is fixed to the lower opening 64 of the container 62. Further, the front glass plate 28 is attached to the upper opening 68 of the container 62 via a rubber plate 66 formed in a donut shape. On the other hand, at the bottom of the container 62, the heater plate 7 formed in a donut shape shown in FIG.
0 is provided. Capillary grooves 72, 72 ... Are radially formed on the surface of the heater plate 70.
The heater plate 70 corresponding to 72 ... Is configured to be able to heat at least one combination.

According to the liquid prism 60 thus constructed, when the heater plate 70 is heated, bubbles are instantly generated on the surfaces of the grooves 72, 72 ... Of the heater plate 70, and the bubbles are generated as shown in FIG. Then, they are collected in the bubble collecting pocket portion 74 formed in the lower portion of the container 62. This allows the container 62
The water pressure inside increases and the rubber plate 66 elastically deforms as shown by the chain double-dashed line. Therefore, the distance between the front glass plate 28 and the rear glass plate 30 increases, so that the optical path length through the water 34 can be varied.

When it is desired to increase the distance between the front glass plate 28 and the rear glass plate 30, the number of the grooves 72, 72 ... Heated by the heater plate 70 is increased, and when the distance is shortened. The number of the grooves 72, 72 ... May be reduced. Accordingly, even if the heater plate 70 is used as the driving unit of the liquid prism, the flexible cylinder 26 can be expanded and contracted along the optical axis, and thus the same effect as that of the liquid prism 12 of the first embodiment described above can be obtained. be able to.

FIG. 10 shows a liquid prism 80 according to the present invention.
4 is a cross-sectional view showing a fourth embodiment of the present invention, and the same or similar members as those of the first embodiment shown in FIG. In the liquid prism 80 shown in the same figure, the side wall 84 of the container 82 is constituted by a heater, and the capillary-shaped grooves 72, 7 shown in FIG.
The same as the grooves 72, 72 ...

The liquid prism 80 having the above structure
Also, the same action and effect as those of the liquid prism 60 of the third embodiment shown in FIG. 8 are achieved. FIG. 11 is a cross-sectional view showing a fifth embodiment of the liquid prism 90 according to the present invention, and the same or similar members as those in the first embodiment shown in FIG. Is omitted.

The liquid prism 90 shown in FIG.
By utilizing the property that the flexible cylinder 26 expands when it is twisted in one direction, the motor including the rotor portion (winding) 92 and the magnet 94 is built in the liquid prism 90, and the frame plate 36 is rotated with respect to the frame plate 38 to change the distance between the front glass plate 28 and the rear glass plate 30. That is, when the frame 36 is rotated with respect to the frame 38 and the flexible tube 26 is twisted, the flexible tube 26 expands, so that the frame 36 rises along the frame 38.

Therefore, the front glass plate 28 and the rear glass plate 30
If a longer distance is required, the motor may be rotated in one direction by a large amount, and if a shorter distance is required, the motor may be rotated in a smaller amount in the same direction. FIG. 12 shows a sixth embodiment of the liquid prism 100 according to the present invention.
It is sectional drawing which shows an Example, and attaches | subjects the same code | symbol about the same or similar member as 1st Example shown in FIG. 3, and abbreviate | omits the description.

Like the liquid prism 90 shown in FIG. 11, the liquid prism 100 shown in FIG. 11 also utilizes the property that the flexible cylinder 26 expands when it is twisted in one direction. A gear 102 is provided on the upper flange portion 101 of the frame plate 38.
The gear 1 of the motor 104 is screwed into this gear 102.
06 is meshed. Further, the motor 104 is fixed to a flange portion 108 formed on the upper portion of the frame plate 38 to be unitized.

The liquid prism 100 having the above structure
Also, when it is desired to increase the distance between the front glass plate 28 and the rear glass plate 30, it is sufficient to rotate the motor 104 largely in one direction, and when it is desired to shorten the distance,
The motor 104 may be rotated a small amount in the same direction. 13 is a sectional view showing a seventh embodiment of the liquid prism 110 according to the present invention, which is the same as the first embodiment shown in FIG.
Alternatively, similar members are designated by the same reference numerals, and description thereof will be omitted.

In the liquid prism 110 shown in the figure, an optical low-pass filter 112 is used as the front glass plate 28 in the flexible cylinder 2.
6, and the front glass 114 of the rear glass plate 30CCD 24 is fixed to the lower end of the flexible tube 26 as its driving portion, and its driving portion is the piezo element 3 similar to that of the first embodiment.
I am using 2. The liquid prism 110 configured as described above also has the same operation and effect as the liquid prism 12 shown in FIG. In addition, the liquid prism 11 of this embodiment
0 is a liquid prism, an optical low-pass filter 112,
Also, the three members of the CCD 24 can be unitized.

In this embodiment, the taking lens optical system 10 is used.
I have explained each of the liquid prisms adapted to
The present invention is not limited to this, but the liquid prisms 12, 12A, 60, 80, 90, 1 shown in the first to sixth embodiments.
00 can be used individually as a variable optical path length prism. Further, by using the liquid prism described in this embodiment for the taking lens optical system 10, the movement space of the focus lens can be deleted, and the movement amount of focusing does not depend on the lens type. It can be used in common for lenses with similar formats. Further, a lens having a small image area has a smaller prism, and therefore a bright lens does not increase in size.

[0031]

As described above, according to the taking lens optical system of the present invention, the liquid prism is arranged instead of the focus lens, and the driving means of the liquid prism is driven to fill the transparent liquid. The flexible cylinder is expanded and contracted, the distance between the transparent plates is expanded and contracted, and the optical path length passing through the liquid is changed to perform focus adjustment. That is, by adapting the liquid prism whose power is smaller than that of the lens, even if some error occurs in the expansion and contraction amount of the flexible cylinder, the focusing is not hindered, and the central axis of the liquid prism is imaged. Even if the optical axis of the lens optical system is tilted or decentered, the optical performance of the taking lens optical system does not deteriorate. Therefore, focusing can be performed with a simple mechanism.

Further, according to the liquid prism of the present invention, the driving means is driven to expand and contract the flexible cylinder filled with the transparent liquid, and the transparent plate fixed to the front end and the rear end of the flexible cylinder. The distance between them is expanded or contracted to change the optical path length through the liquid. By adjusting this variable amount, light can be imaged at a desired position. Furthermore, according to the liquid prism of the present invention,
Since the liquid prism and drive unit can be unitized and can be used in common regardless of the photographic lens optical system, productivity can be improved and cost can be reduced by the photographic lens, and the photographic lens has a focusing function. Since it is unnecessary, the size of the taking lens can be reduced.

[Brief description of drawings]

FIG. 1 is a side view showing an embodiment of a taking lens optical system according to the present invention.

FIG. 2 is a plan view of a liquid prism applied to a taking lens optical system according to the present invention.

FIG. 3 is a sectional view taken along line 3-3 in FIG.

FIG. 4 is an operation explanatory view of a liquid prism applied to a taking lens optical system according to the present invention.

FIG. 5 is an operation explanatory view of a liquid prism applied to a taking lens optical system according to the present invention.

FIG. 6 is an enlarged view of an essential part showing a second embodiment of the liquid prism according to the present invention.

FIG. 7 is a perspective view showing an embodiment of the cam barrel shown in FIG.

FIG. 8 is a sectional view showing a third embodiment of the liquid prism according to the present invention.

9 is a plan view of a heater applied to the liquid prism shown in FIG.

FIG. 10 is a sectional view showing a fourth embodiment of the liquid prism according to the present invention.

FIG. 11 is a sectional view showing a fifth embodiment of the liquid prism according to the present invention.

FIG. 12 is a sectional view showing a liquid prism according to a sixth embodiment of the present invention.

FIG. 13 is a sectional view showing a liquid prism according to a seventh embodiment of the present invention, which is applied to a taking lens optical system.

FIG. 14 is a side view showing the structure of a conventional taking lens optical system.

[Explanation of symbols]

10 ... Photographic lens optical system 12, 12A, 60, 80, 90, 100, 110 ... Liquid prism 24 ... CCD 26 ... Flexible tube 28 ... Front glass plate 30 ... Rear glass plate 32 ... Piezo element 66 ... Rubber plate 112 ... Optical low-pass filter 114 ... CCD front glass

Claims (3)

[Claims] 1. A liquid comprising: a flexible plate having transparent plates fixed to the front end and the rear end thereof, and a flexible cylinder filled with a transparent liquid; and a drive unit for expanding and contracting the flexible cylinder. Focus adjustment is performed by having a prism, arranging the liquid prism on the optical axis of a photographing lens, and expanding and contracting the flexible cylinder by the driving means to change the optical path length passing through the liquid. A photographic lens optical system characterized by this. 2. At least one of the transparent plates fixed to the front end and the rear end is provided via an elastic member, and a container filled with a transparent liquid and an inner wall of the container are provided. A heater provided, and a liquid prism composed of the liquid prism, the liquid prism is arranged on the optical axis of a photographing lens, and the temperature of the liquid is raised by the heater to expand the liquid in the container. A taking lens optical system, wherein elastic adjustment is performed by elastically deforming the elastic member to widen a distance between the transparent plates and varying an optical path length passing through the liquid. 3. A flexible plate having transparent plates fixed to the front end and the rear end and having a transparent liquid filled therein, and a drive means for expanding and contracting the flexible pipe. A liquid prism characterized in that.