Guest-host liquid crystal element with removable polarizer

• US 6,876,412 B2
• Filed: 04/05/2002
• Issued: 04/05/2005
• Est. Priority Date: 04/06/2001
• Status: Expired due to Term

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Yanagida, Toshiharu, Udaka, Toru, Kawabata, Masaru, Nito, Keiichi
• Primary Examiner(s): SCHECHTER, ANDREW M
• Application Number:
  US10/297,304
• Publication Number:
  US 20040012753A1
• Time in Patent Office: 1,096 Days
• Field of Search: 349/56, 349/96, 349/165
• US Class Current: 349/96
• CPC Class Codes: G02B 27/281 used for attenuating light intensity, e.g. comprising rotatable polarising elements
• CPC Class Codes: G02B 5/005 Diaphragms for cameras G03B9/02
• CPC Class Codes: G02F 1/13306 Circuit arrangements or driving methods for the control of single liquid crystal cells G02F1/132, G02F1/133382 take precedence
• CPC Class Codes: G02F 1/133509 Filters, e.g. light shielding masks
• CPC Class Codes: G02F 1/13725 based on guest-host interaction G02F1/13762, G02F1/13737, take precedence
• CPC Class Codes: H04N 23/55 Optical parts specially adapted for electronic image sensors; Mounting thereof
• CPC Class Codes: H04N 23/75 by influencing optical camera components

Abstract

A light control device and an imaging device suitable for the effective and stabilized driving of a Guest-Host type liquid crystal element. A light control device (23) which is provided with a light controlling GH cell (12) and a UV cut filter (65) provided on the light incident side of the GH cell (12), and which is therefore reduced significantly in the quantity of ultraviolet ray applied to the GH cell (12), thereby preventing the photodecompositon or photodegradation of materials constituting a liquid crystal layer in the GH cell (12); and an imaging device such as a CCD camera (50) having this light control device disposed on the optical path thereof.

Claims

1. An imaging device comprising a light control device which comprises a guest-host liquid crystal element for controlling light and which is disposed in an optical path of an imaging system, a polarizer provided in the effective optical path of light incident on the liquid crystal element, and a filter material provided on the light incidence side of the liquid crystal element, for absorbing at least ultraviolet rays;

and, wherein the polarizer can be taken in and out of the effective optical path.

2. An imaging device according to claim 1, wherein the filter material comprises at least one selected from an ultraviolet cut-off film, ultraviolet cut-off coated glass and ultraviolet absorbing glass.

3. An imaging device according to claim 1, wherein the filter material is provided in at least the same area as the section of an effective optical path of incident light.

4. An imaging device according to claim 1, wherein the liquid crystal element is a guest-host liquid crystal element comprising a negative or positive liquid crystal as a host material, and a positive or negative dichroic dye as a guest material.