Light scattering type liquid crystal display panel for timepiece

• US 6,624,858 B2
• Filed: 01/31/2000
• Issued: 09/23/2003
• Est. Priority Date: 08/01/1997
• Status: Expired due to Fees

• Current Assignee: Citizen Holdings Co., Ltd. (Citizen Electronics Company Limited)
• Original Assignee: Citizen Watch Co Limited (Citizen Electronics Company Limited)
• Inventors: Nakagawa, Koji, Sekiguchi, Kanetaka
• Primary Examiner(s): CHOWDHURY, TARIFUR RASHID
• Application Number:
  US09/463,754
• Publication Number:
  US 20020071069A1
• Time in Patent Office: 1,331 Days
• Field of Search: 349/84, 349/62-65, 349/86, 349/96-98, 349/106, 349/113, 349/115
• US Class Current: 349/84
• CPC Class Codes: G02F 1/1334 based on polymer dispersed liquid crystals, e.g. microencapsulated liquid crystals
• CPC Class Codes: G02F 1/133553 Reflecting elements associated to illuminating devices G02F1/133605
• CPC Class Codes: G02F 1/13756 the liquid crystal selectively assuming a light-scattering state G02F1/1334, G02F1/13718 take precedence
• CPC Class Codes: G04G 9/0082 by building-up characters using a combination of indicating elements and by selecting desired characters out of a number of characters or by selecting indicating elements the positions of which represents the time, i.e. combinations of G04G9/02 and G04G9/08

Abstract

A liquid crystal display panel for a timepiece comprises: a polymer dispersed liquid crystal cell (10) which is structured by respectively forming an opposed electrode (2) on a first substrate (1) of a pair of transparent substrates and a signal electrode (4) on a second substrate (3), and sealing a liquid crystal layer (5) containing a liquid crystal and a polymer material between the first substrate (1) and the second substrate (3) to form pixel portions at intersections between the signal electrode (4) and the opposed electrode (2); a reflector (15) which transmits a portion of light, placed on the side of a face, on which the opposed electrode (2) is not formed, of the first substrate (1); and an auxiliary light source placed on the outer side of the reflector (15), so that time information can be displayed with good visibility even when the auxiliary light source is turned off.

Claims

1. A liquid crystal display panel for a timepiece comprising:

a light scattering type liquid crystal cell structured by respectively forming an opposed electrode on a first substrate of a pair of transparent substrates and a signal electrode on a second substrate, and sealing a liquid crystal layer containing a liquid crystal and a polymer material between said first substrate and said second substrate to form pixel portions at intersections between said signal electrode and said opposed electrode;

a reflector placed on a side opposite to said opposed electrode with respect to said first substrate;

a light source having elements for absorbing light energy and emitting light in different wavelengths provided in said liquid crystal layer; and

wherein

said reflector is a reflection-type polarizing film which transmits light linearly polarized in a direction parallel to a transmission axis thereof and reflects light linearly polarized in a direction orthogonal to the transmission axis thereof and an auxiliary light source is provided on a side opposite to said first substrate with respect to said reflector.

2. The liquid crystal display panel for a timepiece according to claim 1, wherein a light absorption film is provided on a side opposite to said first substrate with respect to said reflector.

3. The liquid crystal display panel for a timepiece according to claim 1, wherein a color film with a low scatterability or a color filter is provided between said reflector and said first substrate.

4. The liquid crystal display panel for a timepiece according to claim 1, wherein a color film with a low scatterability or a color filter is provided between said reflector and said auxiliary light source.

5. The liquid crystal display panel for a timepiece according to claim 4, wherein said auxiliary light source is a light source having a light emission characteristic of a complementary color to a wavelength of a color reflected by said reflector.

6. The liquid crystal display panel for a timepiece according to claim 1, wherein a polarizing film is provided on said first substrate side or on an opposite side thereof with respect to said reflection-type polarizing film in such a manner that a transmission axis of said polarizing film and the transmission axis of said reflection-type polarizing film are nearly parallel or orthogonal to each other.

7. The liquid crystal display panel for a timepiece according to claim 6, wherein said auxiliary light source is provided at an outermost position on a side opposite to a visible side of said light dispersed type liquid crystal cell.

8. The liquid crystal display panel for a timepiece according to claim 1, wherein said reflection-type polarizing film is a reflection-type polarizing film which has a reflectance different in response to wavelength within a visible light region.

9. The liquid crystal display panel for a timepiece according to claim 8, wherein said auxiliary light source is provided at an outermost position on a side opposite to a visible side of said light dispersed type liquid crystal cell.

10. The liquid crystal display panel for a timepiece according to claim 9, wherein said auxiliary light source is a light source having a light emission characteristic of a complementary color to a wavelength of a color reflected by said reflector.

11. The liquid crystal display panel for a timepiece according to claim 1, wherein said auxiliary light source is a light source having a light emission characteristic of a complementary color to a wavelength of a color reflected by said reflector.

12. The liquid crystal display panel for a timepiece according to claim 1,

wherein said reflector is made so as to demonstrate a reflection characteristic different between at a region where scattering characteristic and transmission characteristic are controlled and at a region where the scattering characteristic or the transmission characteristic is always demonstrated, by applying a voltage to said liquid crystal layer of said light scattering type liquid crystal cell through said opposed electrode and said signal electrode.