Liquid crystal display device and polarizing plate with a condensing element

• US 9,638,955 B2
• Filed: 04/05/2010
• Issued: 05/02/2017
• Est. Priority Date: 04/06/2009
• Status: Expired due to Fees

• Current Assignee: Nitto Denko Corporation
• Original Assignee: Nitto Denko Corporation
• Inventors: Takemoto, Hiroyuki, Miyatake, Minoru
• Primary Examiner(s): Le, Uyen Chau N
• Assistant Examiner(s): CHU, CHRIS H
• Application Number:
  US12/754,123
• Publication Number:
  US 20100253887A1
• Time in Patent Office: 2,584 Days
• Field of Search: None
• CPC Class Codes: G02B 6/0056 for producing polarisation effects, e.g. by a surface with polarizing properties or by an additional polarizing elements
• CPC Class Codes: G02F 1/133606 including a specially adapted diffusing, scattering or light controlling members
• CPC Class Codes: G02F 1/133607 the light controlling member including light directing or refracting elements, e.g. prisms or lenses
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

A liquid crystal display device according to the present invention includes a rear light source device, a rear polarizing plate, a liquid crystal cell including liquid crystal molecules that are substantially perpendicularly aligned during black display, and a front polarizing plate, which are provided in the stated order, wherein: an absorption axis of a polarizer of the rear polarizing plate is perpendicular to an absorption axis of a polarizer of the front polarizing plate; and condensed light in which a half-value angle in a direction perpendicular to the absorption axis of the polarizer of the rear polarizing plate is smaller than a half-value angle in a direction parallel to the absorption axis of the polarizer of the rear polarizing plate enters the rear polarizing plate. According to the present invention, a liquid crystal display device having an excellent front contrast ratio, and a polarizing plate with a condensing element for realizing the liquid crystal display device having the excellent front contrast ratio may be provided.

Claims

1. A liquid crystal display device, comprising a rear light source device, a rear polarizing plate, a liquid crystal cell including liquid crystal molecules that are substantially vertically aligned during black display, and a front polarizing plate, which are provided in the stated order, wherein:

an absorption axis of a polarizer of the rear polarizing plate is perpendicular to an absorption axis of a polarizer of the front polarizing plate;

condensed light in which a half-value angle Fw1 in a direction perpendicular to the absorption axis of the polarizer of the rear polarizing plate is smaller than a half-value angle Fw2 in a direction parallel to the absorption axis of the polarizer of the rear polarizing plate enters the rear polarizing plate,

the half-value angle Fw1 in the direction perpendicular to the absorption axis of the polarizer of the rear polarizing plate is in a range of 7°

to 30°

, and

a ratio (Fw2/Fw1) of the half-value angle Fw2 to the half-value angle Fw1 is equal to or larger than 1.2.; and

,

further comprising a light diffusion element provided on an opposite side of the front polarizing plate with respect to the liquid crystal cell, wherein the light diffusion element diffuses light exited from the front polarizing plate in at least the direction perpendicular to the absorption axis of the rear polarizing plate.

2. A liquid crystal display device according to claim 1, wherein the half-value angle of the condensed light in the direction perpendicular to the absorption axis of the polarizer of the rear polarizing plate is smaller than half-value angles in other directions.

3. A liquid crystal display device according to claim 2, wherein the rear light source device emits the condensed light.

4. A liquid crystal display device according to claim 2, further comprising a condensing element provided between the rear light source device and the rear polarizing plate, wherein the condensing element collimates light emitted from the rear light source device in a predetermined direction to convert the light into the condensed light.

5. A liquid crystal display device according to claim 1, wherein the rear light source device emits the condensed light.

6. A liquid crystal display device according to claim 1, further comprising a condensing element provided between the rear light source device and the rear polarizing plate, wherein the condensing element collimates light emitted from the rear light source device in a predetermined direction to convert the light into the condensed light.