Transmissive and reflective type liquid crystal display

• US 7,414,684 B2
• Filed: 11/10/2004
• Issued: 08/19/2008
• Est. Priority Date: 12/18/2001
• Status: Expired due to Fees

• Current Assignee: Samsung Display Company Limited (Samsung Electronics Co. Ltd.)
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Kim, Hyung-Guel, Jang, Yong-Kyu
• Primary Examiner(s): Nelms; David
• Assistant Examiner(s): Kim; Richard H
• Application Number:
  US10/985,385
• Publication Number:
  US 20050122453A1
• Time in Patent Office: 1,378 Days
• Field of Search: 349/114
• US Class Current: 349/114
• CPC Class Codes: G02F 1/133536 Reflective polarizers G02F1/13362 takes precedence
• CPC Class Codes: G02F 1/133545 Dielectric stack polarisers
• CPC Class Codes: G02F 1/133555 Transflectors
• CPC Class Codes: G02F 1/133567 on the back side
• CPC Class Codes: G02F 1/133615 Edge-illuminating devices, i.e. illuminating from the side

Abstract

Disclosed is a transmissive and reflective type LCD. In the LCD, a second substrate faces a first substrate. A liquid crystal layer is formed between the first substrate and the second substrate. A first polarizing plate is formed on an outer surface of the first substrate. A second polarizing plate is formed on an outer surface of the second substrate. A backlight is arranged for irradiating incident light onto the polarizing plate. A transparent transflective film is arranged between the first polarizing plate and the backlight for partially reflecting and partially transmitting the incident light. The transparent transflective film includes at least a first layer and a second layer, the first and second layers having different refractivity indexes from each other and are alternatively stacked. By a restoring process occurring between the transflective film and the backlight, a predetermined amount of the incident light is transmitted through the transflective film repeatedly, so that transmissivity and light efficiency are enhanced.

Claims

1. A transmissive and reflective type LCD comprising:

a first substrate;

a second substrate having an inner surface facing the first substrate;

a liquid crystal layer formed between the first substrate and the second substrate;

a first polarizing plate formed on an outer surface of the first substrate;

a second polarizing plate formed on an outer surface of the second substrate;

a backlight for irradiating incident light onto the first polarizing plate; and

a transflective film arranged between the first polarizing plate and the backlight, the transflective film partially reflecting and transmitting a first polarization component of the incident light polarized in a first direction and a second polarization component of the incident light polarized in a second direction orthogonal to the first direction.

2. The transmissive and reflective type LCD of claim 1, wherein the transflective film has isotropic transmission and reflection characteristics independent of polarizing state and direction of the incident light.

3. The transmissive and reflective type LCD of claim 2, wherein the transflective film includes at least a first layer and a second layer, and each of the first layer and the second layer has three main refractive indexes of n_x, n_y, and n_z that satisfy the following relationships:

n1_x=n1_y=n1_z; and

n2_x=n2_y=n2_z≠

n1_z,

wherein the transflective film has a thickness direction of z-axis and a film plane of x-y plane, wherein n1x, n1y and n1z denotes a main refractive index of the first layer in an x-axis, y-axis, and z-axis, respectively, and n2x, n2y and n2z denotes a main refractive index of the second layer in an x-axis, y-axis and z-axis, respectively.

4. A transmissive and reflective type LCD for partially reflecting and transmitting incident light, comprising:

an LC cell including a first substrate, a second substrate having an inner surface that is arranged to face the first substrate, and a liquid crystal layer formed between the first substrate and the second substrate;

a first polarizing plate formed on an outer surface of the first substrate;

a second polarizing plate formed on an outer surface of the second substrate;

a backlight arranged at a rear side of the first polarizing plate; and

a transparent transflective film arranged between the first polarizing plate and the backlight and having a plurality of layers in which a first layer and a second layer have different refractivity indexes from each other, the transflective film partially reflecting the transmitting a first polarization component of the incident light polarized in a first direction and a second polarization component of the incident light polarized in a second direction orthogonal to the first direction,

wherein the transmissive and reflective type LCD has a reflection light path along which the incident light is incident onto the LC cell from a front side of the LC cell, is reflected by the transflective film, and is output through the front side of the LC cell, and a transmission light path along which the incident light is incident onto the LC cell from a rear side of the LC cell, is transmitted through the transflective film, and is output through the front side of the LC cell.

5. The transmissive and reflective type LCD of claim 4, wherein the transflective film has isotropic transmission and reflection characteristics independent of polarizing state and direction of the incident light.

6. The transmissive and reflective type LCD of claim 5, wherein each of the first layer and the second layer has three main refractive indexes of n_x, n_y, and n_z with the following relationships:

n1_x=n1_y=n1_z; and

n2_x=n2_y=n2_z≠

n1_z,

wherein the transflective film has a thickness direction of z-axis and a film plane of x-y plane, wherein n1x, n1y, and n1z denotes a main refractive index of the first layer in an x-axis, y-axis, and z-axis, respectively, and n2x, n2y, and n2z denotes a main refractive index of the second layer in an x-axis, y-axis, and z-axis, respectively.