Imaging apparatus having electrooptic devices which comprise a variable focal length lens

• US 5,071,229 A
• Filed: 08/07/1989
• Issued: 12/10/1991
• Est. Priority Date: 08/08/1988
• Status: Expired due to Term

• Current Assignee: Olympus Optical Company Ltd. (Olympus Corporation)
• Original Assignee: Olympus Optical Company Ltd. (Olympus Corporation)
• Inventors: Simazu, Hisanari, Taniguchi, Akira, Takahashi, Susumu, Nishioka, Kimihiko, Toda, Akitoshi, Takano, Akira, Oaki, Yoshinao, Miyanaga, Hirofumi, Shiraiwa, Masaru, Aoki, Yoshisada
• Primary Examiner(s): Miller, Stanley D.
• Assistant Examiner(s): Mai, Huy K.
• Application Number:
  US07/390,402
• Time in Patent Office: 855 Days
• Field of Search: 350/331 R, 350/334, 350/339 R, 350/347 V, 350/336, 350/335, 350/337
• US Class Current: 349/200
• CPC Class Codes: A61B 1/0019 characterised by variable lenses
• CPC Class Codes: G02B 27/281 used for attenuating light intensity, e.g. comprising rotatable polarising elements
• CPC Class Codes: G02B 3/08 with discontinuous faces, e.g. Fresnel lens diffractive Fresnel lenses G02B5/1876
• CPC Class Codes: G02B 3/14 of variable focal length
• CPC Class Codes: G02F 1/1345 Conductors connecting electrodes to cell terminals
• CPC Class Codes: G02F 1/1347 Arrangement of liquid crystal layers or cells in which the final condition of one light beam is achieved by the addition of the effects of two or more layers or cells
• CPC Class Codes: G02F 1/29 for the control of the position or the direction of light beams, i.e. deflection
• CPC Class Codes: G02F 1/294 Variable focal length devices

Abstract

An imaging apparatus is provided with a negative lens, a variable focal length lens unit including a material with an electrooptic effect, a light blocking unit, including the material with the electrooptic effect, capable of changing an aperture diameter, and a switch, interlocked with each other, capable of supplying electric power to the variable focal length lens unit and the light blocking unit which are arranged in order on an optical axis from an object side to an image side. When the switch is turned off, the variable focal length lens unit is set to bring an object at a far point into focus and the light blocking unit is set so that an aperture is determined by an aperture stop, while on the other hand, when the switch is turned on, the variable focal length lens unit is set so that an object at a near point is in focus and the light blocking unit is set to be smaller in aperture. Apertures different in size are determined by a plurality of annular transparent electrodes incorporated in the light blocking unit and configured concentrically. Thus the imaging apparatus can be constructed to be small or compact in size and is easy in manufacturing.

Claims

1. An imaging apparatus having electrooptic devices, comprising:

a variable focal length lens including;

a liquid crystal lens; and

a first polarizing plate arranged on one side of said liquid crystal lens;

light blocking means including;

a light blocking plate having an aperture;

a second polarizing plate disposed on the opposite side of said liquid crystal lens and in a portion excluding a central area smaller in diameter than said aperture of said light blocking plate, said second polarizing plate having a plane of polarization oriented in a different direction from that of said first polarizing plate; and

optically active means disposed between said first and second polarizing plates;

first power source means for actuating said liquid crystal lens; and

second power source means for synchronously actuating said optically active means with said first power source means.

2. An imaging apparatus according to claim 1, where said first polarizing plate includes a central transparent part having a diameter smaller than that of that said aperture of said light blocking plate.

9. An imaging apparatus according to any one of claims 1 to 5, wherein said liquid crystal lens comprises a pair of lens elements facing to each other through a spacer with electrical insulation characteristics, transparent electrodes provided on inner surfaces, facing to each other, of said pair of lens elements, and a liquid crystal charged in space produced by said spacer and said pair of lens elements, cutting portions are configured in at least one of each of said lens elements and said spacer, and lead wires for applying voltages to said transparent electrodes and connections with said transparent electrodes are constructed in said cutting portions.

11. An imaging apparatus according to any one of claims 1, 2, 3, 4, or 5, further comprising a birefringent plate disposed on the optical axis and located on an opposite side of the liquid crystal lens in relation to one of said first and second polarizing plates.

12. An imaging apparatus according to any one of claims 1, 2, 3, 4, or 5, wherein the central area of one of said polarizing plates is transparent.

13. An imaging apparatus according to any one of claims 1, 2, 3, 4, or 5 wherein the central area of one of said polarizing plates has a polarizing direction different from that of an area outside the central area.

14. An imaging apparatus according to claim 11, wherein the central area of one of said polarizing plates has a polarizing direction different from that of an area outside the central area.

3. An imaging apparatus having an electrooptic effect, comprising:

first and second polarizing plates arranged on an optical axis having a space therebetween;

a liquid crystal lens, disposed on the optical axis in said space between said first and second polarizing plates, containing liquid crystal molecules enclosed in a lens-shaped cell to be drawn up in a twist alignment;

a light blocking plate having an aperture disposed on the optical axis; and

first power source means for actuating said liquid crystal lens;

wherein one of said first and second polarizing plates is provided with a central area smaller in diameter than that of said aperture of said light blocking plate; and

wherein a direction of a plane of polarization of light emitted from said liquid crystal lens depends upon whether said liquid crystal lens is actuated.

4. An imaging apparatus according to claim 3, wherein said lens-shaped cell of said liquid crystal lens includes one surface disposed so that a peripheral part and a central part of said lens-shaped cell are different in shape from each other.

5. An imaging apparatus according to claim 4, wherein liquid crystal molecules of an area corresponding to the central part of said liquid crystal lens are drawn up in a homogeneous alignment.

6. An imaging apparatus according to claim 3, further comprising a lens including a birefringent material, which is disposed on an image side of said light blocking plate.

7. An imaging apparatus having electrooptic devices, comprising:

a variable focal length lens including a material having an electrooptic effect;

light blocking means disposed on an optical axis of said variable focal length lens, for changing an aperture to different sizes; and

power source means for actuating said variable focal length lens so that a focal length of said variable focal length lens is changed synchronously with the change of said aperture;

wherein said light blocking means includes first and second polarizing plates, disposed on the optical axis of said variable focal length lens having a space therebetween, the first and second polarizing plates having the same polarizing direction, and a liquid crystal cell, disposed on the optical axis in said space and enclosing a nematic liquid crystal, said liquid crystal cell being provided with a first orientation film, on an object side thereof, having an orientation such that an orientation direction of liquid crystal molecules is the same as the polarizing direction of said polarizing plates and a second orientation film, on an image side thereof, which includes a central small-diameter area where the orientation direction is the same as that of said first orientation film and a remaining area having an orientation direction perpendicular to that of said first orientation film.

8. An imaging apparatus having electrooptic devices, comprising:

a variable focal length lens containing a material having an electrooptic effect;

light blocking means disposed on an optical axis of said variable focal length lens, for changing an aperture to different sizes; and

means for synchronously changing a focal length of said variable focal length lens with a change of said aperture;

said light blocking means including a first polarizing plate disposed on the optical axis of said variable focal length lens, a second polarizing plate, spaced from said first polarizing plate on the optical axis, having a plane of polarization perpendicular to a polarizing direction of said first polarizing plate and a small-diameter area free from a polarizing function at a central portion thereof, and a liquid crystal cell, disposed on the optical axis between said first and second polarizing plates, said liquid crystal cell enclosing a nematic liquid crystal, said liquid crystal cell being provided with a first orientation film, on an object side thereof, having an orientation direction identical with the polarizing direction of said first polarizing plate and a second orientation film, on an image side thereof, having an orientation direction perpendicular to that of said first orientation film.

10. An imaging apparatus having electro-optic devices, comprising:

a variable focal length lens including

a liquid crystal lens; and

a first polarizing plate disposed on one side of said liquid crystal lens;

light blocking means including;

an aperture stop;

optically active means; and

a second polarizing plate disposed on the opposite side of said liquid crystal lens and in a portion excluding a central area smaller in diameter than said aperture stop, said second polarizing plate also having a plane of polarization perpendicular to a plane of polarization of said first polarizing plate;

first power source means for supplying electric power to said liquid crystal lens; and

second power source means for supplying electric power t said optically active means,

wherein said first and second power source means are operated synchronously; and

wherein said optically active means has a pair of transparent plates facing each other through a spacer with electrical insulation characteristics, transparent electrodes provided on inner surfaces, facing each other, of said pair of transparent plates, and a liquid crystal made up of said spacer and said pair of transparent plates, wherein cutting portions are configured in at least one of each of said transparent plates and said spacer, and wherein lead wires for supplying voltages to said transparent electrodes and connections with said transparent electrodes are constructed in said cutting portions.

15. An imaging apparatus having electrooptic devices, comprising:

a variable focal length lens containing a material with an electrooptic effect;

light blocking means including;

a first polarizing plate disposed on one side of said variable focal length lens;

a second polarizing plate with a transparent central area, said second polarizing plate having a plane of polarization perpendicular to a plane of polarization of said first polarizing plate, except for the central area that has no polarizing effect;

a liquid crystal cell disposed between said first and second polarizing plates, having zonal transparent electrodes that sandwich a nematic liquid crystal with concentric apertures different in size from each other; and

switch means for selectively supplying electric power to said zonal transparent electrodes to determine a diameter of an aperture in response to a change of a focal length of said variable focal length lens, said switch means enabling an aperture to be changed to different sizes; and

power source means for actuating said variable focal length lens so that the focal length of said variable focal length lens is changed synchronously with the change of said aperture.