WO2008120833A1

WO2008120833A1 - Lcd having window endowed front light function

Info

Publication number: WO2008120833A1
Application number: PCT/KR2007/001600
Authority: WO
Inventors: Jang Hwan Hwang; Jung Ju Kim; Seon Wook Hwang; Jung Woon Park
Original assignee: Namotek Co., Ltd.
Priority date: 2007-04-02
Filing date: 2007-04-02
Publication date: 2008-10-09

Abstract

Disclosed is a liquid crystal display (LCD) having a window endowed with a front light function. The LCD of the present invention comprises a liquid crystal panel; a reflection sheet disposed at a rear side of the liquid crystal panel to reflect light advancing through the liquid crystal panel to the front; and the window disposed in front of the liquid crystal panel and having front light function by including a plurality of reflection lens protrusions on a rear surface thereof for refracting incident light to advance the light nearly perpendicularly to the liquid crystal panel and advancing emitted light to the front.

Description

LCD HAVING WINDOW ENDOWED FRONT LIGHT

FUNCTION

Technical Field

[1] The present invention relates to a liquid crystal display (LCD) endowed with a window having front light function, and more particularly to an LCD capable of guaranteeing high brightness throughout the whole light emitting surface when reflecting and emitting light received from the front, thereby providing a clearer image for a user. Background Art

[2] A liquid crystal display (LCD) has been popularly used as a computer monitor, a display panel of a cell phone and the likes, because it can be implemented in slim and compact structure and reduce power consumption.

[3] The LCD implements a specific image by converting arrangement of liquid crystalline material while light is supplied and emitted to the outside. Based on the light supplying method, a back light unit (BLLI) or a front light unit (FLLI) is selectively adopted.

[4] When the BLLI is applied to the LCD, the whole size and weight of the LCD are increased. Especially, excessive power is consumed for light emission of the back light.

[5] In order to overcome such problems, an LCD applying the FLLI has been developed and used.

[6] FIG. 1 is an exploded perspective view showing main parts of a conventional LCD applying the FLLI. FIG. 2 is a sectional view of the LCD of FIG. 1 as constructed.

[7] Referring to FIG. 1 and FIG. 2, the LCD comprises a liquid crystal panel 1 injected with liquid crystalline material therein, a front light panel 2 disposed in front of the liquid crystal panel 1 to receive light from the outside and transmit the light to the liquid crystal panel 1, a reflection sheet 3 disposed at a rear side of the liquid crystal panel 1 to reflect the received light, and a light source 5 dedicatedly formed at one side of the front light panel 2 to supply light when natural light from the outside is unavailable.

[8] A window 4 is disposed in front of the front light panel 2 to protect the front light panel 2. For example, the window 4 may be integrally fixed to a casing of a display device such as a cell phone, thereby protecting the front light panel 2 from external shocks.

[9] The above-structured LCD operates as follows. When the natural outside light is received to the reflective liquid crystal panel 1, passing through the window 4 and the front light panel 2, the incident light is reflected from the reflection sheet 3 disposed under the liquid crystal panel 1 and emitted to the outside. The emitted light embodies a desired image by properly arranging the liquid crystalline material so that a user can directly view the image.

[lϋ] Since the above LCD applying the FLU selectively uses one or more of the natural light and the light source, power consumption can be highly reduced in comparison with conventional backlight surface-light source devices.

[11] In addition, a drive circuit 6 is provided at a lower part of the reflection sheet to supply electric signals to the liquid crystal panel 1 and drive the light source 5.

[12] In the above front light panel of LCD, if an incident angle of the light is nearly 90 degree, the efficiency of reflection and emission of the reflection sheet is not deteriorated. However, if the incident light is somewhat inclined, especially near the horizontal, level of brightness of the emitted light is deteriorated remarkably because a reflection angle of the light is the same as the incident angle.

[13] In this case, the image displayed on the liquid crystal panel 1 is hardly recognizable by naked eyes. To be worse, when luminosity of the natural light supplied from the outside is insufficient, the image itself may become unrecognizable.

[14] Additionally, although the front light method is advantageous in achieving slimness more than the back light method, the dedicated window for protecting the front light panel 2 increases the whole thickness.

Disclosure of Invention

Technical Problem

[15] Therefore, the present invention has been made in view of the above-mentioned problems, and it is an object of the present invention to provide a liquid crystal display (LCD) endowed with a window having front light function, capable of improving level of brightness by refracting light incident at various angles so that the light reflected from a reflection sheet is emitted as perpendicularly as possible, and implementing thinner structure by having the front light function in itself. Technical Solution

[16] According to an aspect of the present invention, there is provided a liquid crystal display (LCD) comprising a liquid crystal panel; a reflection sheet disposed at a rear side of the liquid crystal panel to reflect light advancing through the liquid crystal panel to the front; and a window disposed in front of the liquid crystal panel and having a plurality of reflection lens protrusions on a rear surface thereof for refracting incident light to advance the light nearly perpendicularly to the liquid crystal panel and advancing emitted light to the front. Advantageous Effects

[17] According to the present invention, most incident light passing through protrusions of a reflection lens of a window is refracted by the protrusions to be nearly perpendi cular with regard to a surface of a liquid crystal panel, and then reflected and emitted out through the window. Therefore, the light being emitted through the window is able to maintain high brightness level. Accordingly, a user can be provided with a clearer image while quality of the LCD can be improved.

[18] In addition, since the window according to the present invention can function as a front light by itself, a dedicated front light unit is not required. As a result, thickness and weight of the LCD can be highly reduced. Brief Description of the Drawings

[19] The foregoing and other objects, features and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings in which:

[20] FIG. 1 is a perspective view of a liquid crystal display (LCD) according to a related art;

[21] FIG. 2 is a sectional view of the LCD of FIG. 1 as constructed,

[22] FIG. 3 is a sectional view of an LCD according to an embodiment of the present invention;

[23] FIG. 4 is a plan view of a window of an LCD, according to the embodiment of the present invention;

[24] FIG. 5 is a plan view of a window of an LCD, according to another embodiment of the present invention; and

[25] FIG. 6 is a plan view of a window of an LCD, according to yet another embodiment of the present invention. Best Mode for Carrying Out the Invention

[26] Hereinafter, an exemplary embodiment of the present invention will be described in detail with reference to the accompanying drawing figures.

[27] Referring to FIG. 3, a liquid crystal display (LCD) according to an embodiment of the present invention comprises a liquid crystal panel lϋ injected with liquid crystalline material therein and equipped with a reflection sheet 11 at one side, and a window 30 disposed in front of the liquid crystal panel 10. The window 30 may be integrally fixed to a casing of a display device, for example a cell phone, to protect the front light panel 10 from external shocks and function as a front light.

[28] As generally known, the liquid crystal panel 10 is connected to an electric/ electronic circuit for creating a desired image by varying arrangement of the liquid crystalline material injected therein. Also, the liquid crystal panel 10 is provided with electrodes and wires to be supplied with signals and power from the electric/electronic circuit.

[29] The reflection sheet 11 is disposed at a rear side of the liquid crystal panel lϋ, that is, under the liquid crystal panel lϋ in the drawing so that the light passed through the liquid crystal panel lϋ is reflected toward the liquid crystal panel lϋ.

[3ϋ] In order to perform the front light function, the window 30 refracts the incident light to advance the light to the liquid crystal panel 10 nearly perpendicularly. The window 30 includes a reflection lens surface 31 on the side facing the liquid crystal panel 10, in other words, on a rear surface of the window 30 so that the reflected light is emitted toward a front of the user's sight.

[31] The reflection lens surface 31 has a plurality of reflection lens protrusions 32 so as to refract the light and endow the forward emitted light with directivity.

[32] Additionally, a light source 22 is formed at one side of the window 30 to supplement light in case that supply of the light from the outside is unavailable or insufficient.

[33] A light emitting diode (LED) or a combination of cold cathode fluorescent lamp

(CCLF) and reflective element may be used as the light source 22.

[34] The window 30 is the member where the outside light is first received. The reflection protrusions 32 forming reflection patterns for functioning as the front light may be formed on the window 30 by printing or injection-molding. The window 30 may be made of high-molecule resin or tempered glass. The high-molecule resin having high transmittance can efficiently receive the outside light and emit the light reflected from the reflection sheet 11. The tempered glass is suitable for optical use since having excellent impact resistance.

[35] More specifically, the window 30 is sure made of a transparent medium for transmittance. Among the high-molecule resin. Poly Methyl Methacrylate (PMMA) or Poly Carbonate (PC) having high transmittance and durability are appropriate for the window 30.

[36] A drive circuit 40 supplies electric signals to the liquid crystal panel 10, thereby maintaining specific arrangement of the liquid crystalline material, and drives the window 30.

[37] FIG. 4 shows the reflection lens protrusions 32 of the window 30 according to an embodiment of the present invention. A plan view of the reflection lens protrusion 32 has a polygonal shape, and a side view has a pyramid shape. Referring to FIG. 4, the side view is a triangular pyramid. The reflection lens protrusions 32 induce the incident light to be refracted and advanced to the liquid crystal panel 10 as perpendicularly as possible.

[38] Accordingly, the light having a nearly perpendicular incident angle is reflected nearly perpendicularly from the reflection sheet 11 of the liquid crystal panel lϋ. Therefore, the light emitted out through the window 30 is advanced toward the front of the user's sight, thereby minimizing loss of the light and improving level of brightness.

[39] Here, the reflection lens protrusions 32 may be arranged at random. However, regular arrangement of the reflection protrusions 32 is recommended for uniform reception and emission of the light throughout the window 30.

[40] For instance, as shown in FIG. 4, the reflection lens protrusions 32 having a triangular pyramid shape are arranged in plural rows and columns. Furthermore, inverse reflection lens protrusions 32 are interposed among the respective reflection lens protrusions 32 so as to improve the light reception efficiency by increasing areas for receiving the light.

[41] More specifically, the reflection lens protrusions 32 are compactly arranged leaving no vacancy throughout the whole surface of the window 30. For this configuration, sides of respective polygons of the reflection lens protrusions 32 are adjoined one another.

[42] FIG. 5 and FIG. 6 show other embodiments of the reflection lens protrusions 33 formed on the window 30, having a quadrangular pyramid shape.

[43] The reflection lens protrusions 33 having a quadrangular pyramid shape can be uniformly alternated in zigzags as shown in FIG. 5, or arranged in regular grid pattern adjoining one another as shown in FIG. 6.

[44] Regardless of the arrangement type, the reflection lens protrusions 33 refract and advance the light incident from the front or the side, nearly perpendicularly to the 1 iquid crystal panel 10. Thus, the window 30 functions as the front light. As a result, the front light unit can be embodied without a dedicated front light panel.

[45] While the invention has been shown and described with reference to certain embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Industrial Applicability

[46] The present invention can be applied to windows of a liquid crystal display (LCD) of various portable terminals, portable appliances and display devices.

Claims

[1] A liquid crystal display (LCD) comprising: a liquid crystal panel; a reflection sheet disposed at a rear side of the liquid crystal panel to reflect light advancing through the liquid crystal panel to the front; and a window disposed in front of the liquid crystal panel and having front light function by including a plurality of reflection lens protrusions on a rear surface thereof for refracting incident light to advance the light nearly perpendicularly to the liquid crystal panel and advancing emitted light to the front.

[2] The LCD of claim 1, wherein the reflection lens protrusions have a polygonal pyramid shape.

[3] The LCD of claim 2, wherein the reflection lens protrusions are adjoined one another by sides thereof so that no plane surface is left on the window.

[4] The LCD of any of claims 1 through 3, wherein the reflection lens protrusions are arranged in plural rows and columns.

[5] The LCD of claim 4, wherein inverse reflection lens protrusions are interposed among the respective reflection lens protrusions regularly arranged.

[6] The LCD of any of claims 1 through 3, further comprising a light source disposed at one side of the window to supply light into the window through a lateral edge of the window.

[7] The LCD of any of claims 1 through 3, wherein the window is fixed to a casing of a cell phone.