KR100615834B1 - Liquid crystal display device for improving brightness - Google Patents

Abstract

 The present invention is composed of P wave and S wave, and any one of the white light generated from the lamp of the lamp unit passing through the polarizing plate attached to the TFT substrate is incident directly to the light guide plate, and the waveform not passing through the polarizing plate is inside the lamp unit. The present invention relates to a liquid crystal display device and a brightness enhancement method in which a luminance is doubled by being modulated into a waveform that can pass through a polarizing plate and then incident on a light guide plate. In addition, the manufacturing cost may be greatly reduced, and the luminance outside the liquid crystal display panel may be greatly increased such that the luminance of the lamp unit and the luminance outside the liquid crystal display panel are close to each other.

Increased brightness, liquid crystal display panel, lamp unit

Description

Liquid crystal display device for improving brightness

1 is a partially exploded perspective view of a liquid crystal display according to the present invention.

2 is an exploded perspective view illustrating a liquid crystal display module which is a component of a liquid crystal display according to the present invention.

3 is a cross-sectional view taken along the line A-A of FIG. 1 to illustrate a preferred embodiment of a lamp unit that is a component of a liquid crystal display module according to the present invention;

4 is an enlarged view of the circle of FIG. 3.

5 is an explanatory diagram for explaining an operation of improving luminance by the liquid crystal display device according to the present invention;

Figure 6 is a partial cross-sectional perspective view for showing the overall shape and cross section of the light guide plate according to the present invention.

7 is an explanatory diagram for explaining conditions under which white light is reflected or refracted by two members having different media according to the present invention;

8 is a perspective view showing another embodiment of the present invention.

FIG. 9 is a cross-sectional view of the lamp unit portion in the assembled state of FIG. 8; FIG.

10 is an explanatory diagram for explaining the operation of another embodiment of the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device and a brightness enhancement method of improving brightness, and in particular, any one waveform generated from a lamp of a lamp unit and passing through a polarizing plate attached to a TFT substrate among P and S waves is a light guide plate. The other waveform that is incident immediately and does not pass through the polarizing plate is converted into a waveform that can pass through the polarizing plate attached to the TFT substrate inside the lamp unit, and then enters the liquid crystal display panel through the light guide plate to double the luminance. A device and a method for improving brightness.

Recently, the development of a liquid crystal display device capable of gradually increasing in size and implementing a full color display with low power consumption and low voltage driving is rapidly progressing.

Since the liquid crystal display having various advantages is a non-light emitting device (or a passive device), it is impossible to display in a dark place without a light source or a low luminance, so that a light supply device may be used to improve display or display quality even in a dark place. in need.

In this context, a liquid crystal display device having a high brightness and a uniform brightness has been developed by a lamp for generating high brightness and a light guide plate that has increased brightness uniformity.

However, despite the development of high-brightness lamps, there are many differences between the luminance generated in high-brightness lamps and the luminance expressed in liquid crystal display devices. The difference in luminance is that white light generated in high-brightness lamps is formed on the bottom of the TFT substrate. Since about 50% of the light passes through the attached polarizer and is not absorbed by the polarizer, the polarizer is absorbed by the polarizer itself. As a result, the luminance felt outside the LCD is only about half that of the high brightness lamp.

To improve this, US Patent Publication No. 4,798,448, "High Efficiency Lighting System for Display Devices," describes P- and S-waves that form white light on the path through which white light generated by a lamp passes. One waveform is totally reflected, and the other waveform is provided with a panel having the property of passing through, and the waveform passed through the panel is reflected back to the phase difference plate is converted into a waveform reflected on the panel and then totally reflected on the panel generated in the lamp The countermeasure which can use all white light without loss is disclosed.

However, in order to manufacture the light guide plate of the backlight assembly which is widely used in the liquid crystal display device by applying the technical idea of the conventional "high efficiency lighting system for display device", the light guide plate manufacturing material and the medium are essential in the mold for manufacturing the light guide plate. The injection molding should be performed while setting a plurality of other polarizing members to satisfy the known Brewster's angle with respect to the horizontal. This manufacturing process is difficult and not easy to injection, and there are many difficulties in making the polarizing member achieve the Brewster's angle with respect to the horizontal.

 Accordingly, the present invention has been made in view of such a conventional problem, and an object of the present invention is to convert all the light generated from the lamp unit itself into the lamp unit so that all of the liquid crystal display panel can pass therethrough, and thus the luminance generated from the lamp unit of the backlight assembly. The difference in luminance displayed on the liquid crystal display device is minimized.

Still other objects of the present invention will become more apparent from the detailed description of the invention which will be described later.

In order to achieve the object of the present invention, a liquid crystal display device having improved luminance includes a TFT substrate having a first polarizing plate for selectively passing only P waves constituting white light and S waves among S waves, an S wave transmitting polarizing plate, and a predetermined angle. A color filter substrate having a twisted second polarizing plate attached thereto, a liquid crystal display panel including a liquid crystal injected between the color filter substrate and the TFT substrate, an S wave passing through the first polarizing plate, and a P wave not passing through the first polarizing plate Lamp unit including a lamp for generating a mixture of white light, a lamp cover for guiding white light in one direction, and a polarization converting means for converting P waves into S waves, and an S wave positioned under the liquid crystal display panel and converted by the polarization converting means. It includes a light guide plate to be incident to the first polarizing plate, S-wave angle correction means and the receiving container seated between the light guide plate and the first polarizing plate.

Hereinafter, two embodiments of a liquid crystal display device having improved luminance and a method adopted to improve the luminance will be described with reference to the accompanying drawings.

1 is a partially exploded perspective view of the liquid crystal display device, and the liquid crystal display device 800 generally includes a case 100 and a liquid crystal display module 200.

The case 100 again fixes the front case 10 and the liquid crystal display module 200 having an opening defining an effective display area of the liquid crystal display module 200, and the rear case 20 coupled to the front case 10. It is preferable that the front case 10 and the rear case 20 are made of magnesium alloy, which is light and high in strength, and useful for grounding and electromagnetic shielding.

The liquid crystal display module 200 receives a display signal transmitted from an information processing apparatus such as a computer main body (not shown) and displays the text as a character, a symbol, a still picture, or a moving picture that can be recognized by a user. 2 is an exploded perspective view illustrating an exploded view of the liquid crystal display module of the liquid crystal display device of FIG. 1.

The liquid crystal display module 200 generally includes a liquid crystal display panel 300, a backlight assembly 400, and a chassis 700.

Specifically, the liquid crystal display panel 300 includes a TFT substrate 310, a color filter substrate 320, a liquid crystal (not shown), a tape carrier package 330, and a printed circuit board (not shown).

More specifically, the TFT substrate 310 may include a thin film transistor (TFT device) (not shown) formed on a glass substrate by a semiconductor thin film process, a transparent pixel electrode electrically connected to the TFT device, and a TFT device to implement a set resolution. And a signal line consisting of a gate line and a data line to selectively turn on and turn off, so that power is selectively applied to the TFT element so that power is applied to the transparent pixel electrode. do.

The color filter substrate 320 includes a common electrode, an RGB pixel, and a black matrix formed on one side of the transparent glass substrate so as to face the transparent pixel electrode, and the color filter substrate 320 and the TFT substrate 310 face each other and are mutually opposite. Spaced to have a spacing of several μm.

As described above, the liquid crystal is injected and sealed between the color filter substrate 320 and the TFT substrate 310, and polarizing plates 315 and 325 (see FIG. 4) are attached to the upper surface of the color filter substrate 320 and the TFT substrate 310. .

One end of each of the signal lines formed on the above-mentioned TFT substrate 310 is connected to one end of the flexible tape carrier package 330 equipped with a drive drive IC for controlling the drive signal by an anisotropic conductive film (not shown). The other end of the tape carrier package 330 is connected to a printed circuit board for applying a driving signal to the drive IC of the tape carrier package 330 by soldering or the like.

However, even when the display signal is applied to the liquid crystal display panel 300 formed as described above from an external information processing apparatus (not shown), the TFT element is turned on to form an electric field between the common electrode and the pixel electrode to form the liquid crystal. Without the light passing through, it is impossible to display the desired information, which necessitates the aforementioned backlight assembly 400.

One embodiment of the backlight assembly 400 that satisfies this need is illustrated in more detail with reference to FIGS. 2 to 4, which will be described in more detail with reference to the accompanying drawings. As follows.

The backlight assembly 400 again supplies a storage container 410 having a predetermined storage area, a reflecting plate 420 accommodated on the bottom surface of the storage container 410, and white light as polarized light passing through the aforementioned polarizing plate 315. A light guide plate 440 that uniformly guides the polarization made by the lamp unit 430, the lamp unit 430 toward the liquid crystal display panel 300, and a reverse prism sheet seated on an upper surface of the light guide plate 440; ).

More specifically, the light guide plate 440 is a wedge type in which the thickness of the light guide plate 440 becomes thinner gradually from one end to the opposite end in a rectangular parallelepiped shape in one embodiment, and the bottom surface of the light guide plate 440 is mirror-processed and cut out of the light guide plate 440. A triangular groove 445 is formed at the bottom of the light guide plate 440 so as to be parallel to one side surface of the light guide plate 440.

The density of the triangular groove 445 is formed in the light guide plate 440 is formed higher toward the other side facing than the density in the cut one side.

The lamp unit 430 is installed in the light guide plate 440 formed as described above, and the lamp unit 430 is composed of a lamp cover 431, a lamp 432, and an optical modulation device 439.

In detail, the lamp cover 431 including the lamp 432 is installed on the upper surface of the thickest end of the light guide plate 440.

In one embodiment, the optical modulation device 439 has two triangular pillar shapes in which a rectangular parallelepiped having a height equal to the thickest portion of the light guide plate 440 and a length equal to the width of the light guide plate 440 is diagonally cut. The triangular pillar is in close contact with the thickest side of the steel plate 440 in a state in which the inclined surface is butt joint.

The two triangular pillars will be again defined as a first optical modulator body 438 and a second optical modulator body 433.

The first light modulator body 438 is made of the same material as the light guide plate 440, and the second light modulator body 433 is made of a light guide plate 440 and a material of a medium.

3 or 4, a first plate 436 for light modulation is formed on a bottom surface of two surfaces that form a right angle of the second optical modulator body 433 having a triangular pillar shape. The second plate 437 for light modulation is formed on the side surface perpendicular to the bottom surface of the second light modulator body 433. Unexplained reference numeral 434 is an inclined surface of the second light-healing device.

The light modulation first plate 436 is formed by stacking a phase difference plate and a reflection plate again, and the light modulation second plate 437 is formed of a reflection plate.

Here, the retarder serves to change the waveform of light, and the role and function of the retarder will be described later in detail.

On the other hand, the inverted prism sheet 450 is seated on the upper surface of the light guide plate 440 described above, the reverse prism sheet 450 is processed so that the bottom surface facing the light guide plate 440 is formed to have a triangular irregularities and the top surface is flat It is processed.

After the reflecting plate 420, the light guide plate 440, the lamp unit 430, and the reverse prism sheet 450 are accommodated in the storage container 410 of the backlight assembly 400 configured as described above, the upper surface of the reverse prism sheet 450 is disposed. After the liquid crystal display panel 300 described in detail above is seated, the chassis 700 and the storage container 410 are firmly coupled to the liquid crystal display module 800.

A method of improving luminance by the liquid crystal display module 800 will now be described with reference to FIG. 5 or 7.

First, white light is generated in an arbitrary direction in the lamp 432 of the lamp unit 430. The white light is light in which P-wave polarization and S-wave polarization are mixed (indicated by the black arrows in FIG. 5).

As described above, the white light generated in an arbitrary direction from the lamp 432 is changed in one direction (in the present invention, toward the first light modulator 438) by the lamp cover 431, and then the white light is first light modulated. The device body 438 is incident at a predetermined angle.

At this time, the white light incident to the inside of the first optical modulator body 438 reaches the inclined surface 434 that is the boundary between the second optical modulator body 433 and the first optical modulator 438. The light is reflected or polarized according to the refractive indices and the incident angles of the second optical modulator 433 and the first optical modulator 438.

n1sin (θp) = n2 sinθ2

Referring to FIG. 7, θ ₂ is a refraction angle and (θ p) is a Brewster's angle. If the reflected light is fully polarized, since the reflected light and the refracted light form 90 ° and the reflection angle and the incident angle are the same, θp may be summarized as in Equation 2 below.

θ2 = 90 °-(θp)

Substituting <Equation 2> into <Equation 1>, <Equation 1> becomes tan (θp) = n ₁ / n ₂ to obtain θp. Here, n ₁ is the refractive index of the first optical modulation device body 438, n ₂ is the refractive index of the second light modulation device body 435.

Referring again to FIG. 5, an angle between the incidence angle of the white light incident on the first optical modulation device body 438 and the normal line I perpendicular to the inclined surface 434 of the second light modulation device 433 is θp. If satisfied, a portion of the S wave of the P wave and the S wave (dot hatched inside the arrow) included in the white light is totally reflected to be incident into the light guide plate 440 in a direction parallel to the upper surface of the light guide plate 440.

In this case, the S wave is a waveform passing through the polarizing plate 315 attached to the TFT substrate 310 of the liquid crystal display panel 300, and the P wave is a waveform not passing through the polarizing plate 315.

In addition, the P wave and the S wave not totally reflected toward the light guide plate 440 enter the second light modulation device body 433 and reach the first plate 436 for light modulation.

Among them, the P wave is circularly polarized in the retardation plate of the first plate 436 for light modulation, modulated by the S wave, and totally reflected by the reflecting plate, and the S wave is totally reflected by the reflecting plate immediately without being modulated by the retardation plate.

That is, the P wave and some S waves which are not incident on the light guide plate 440 by the light modulation first plate 436 can be modulated to S waves.

The light-modulated S-waves are totally reflected in the direction from the boundary surface 434 of the second optical modulation device 433 to the second plate 437 for light modulation, and then by the reflecting plate of the second plate 437 for light modulation. By specular reflection, the light guide plate 440 has a direction parallel to the upper surface of the light guide plate 440, and then enters into the light guide plate 440.

Accordingly, the polarizing plate 315 may not pass through the polarizing plate 315 formed on the TFT substrate 310 of the liquid crystal display panel 300 among P waves and S waves included in the white light generated by the lamp 432 of the lamp unit 430. The optical efficiency can be doubled by modulating the P wave that is absorbed into the S wave by the second optical modulator 433 to cause the decrease in the light efficiency.

On the other hand, all the S-waves incident in parallel with the upper surface of the light guide plate 440 proceeds to the inside of the light guide plate 440 and is reflected by the triangular groove 445 and the mirror surface formed on the bottom surface of the light guide plate 440, where the reflection angle is the light guide plate. It has an angle of about 60 ° to 70 ° based on the top surface of 440.

In addition, the S-waves emitted from the light guide plate 440 are directly refracted by the inverse prism sheet 450 so that the angle of the liquid crystal display panel 300 is changed to an angle close to 90 ° with respect to the top surface of the light guide plate 440. After passing through the polarizing plate 315, and passes through the liquid crystal layer and the color filter substrate 320 to reach the eyes of the user.

According to the embodiment of the present invention described above, the light efficiency is doubled by allowing all of the white light generated by the lamp 432 to pass through the polarizing plate 315 of the TFT substrate 310, but the second optical modulation device body 433 is provided. The first plate 436 for light modulation and the second plate 437 for light modulation require the lamp unit 430 to be positioned higher than the light guide plate 440, thereby reducing the overall thickness of the liquid crystal display module 200. It acts as a factor to increase the thickness of the liquid crystal display device 800 is difficult.

Accordingly, the present invention provides another embodiment for overcoming such additional problems caused by the embodiment of the present invention, and details another embodiment of the present invention with reference to FIGS. 8 to 10. If you explain it as follows.

8 is an exploded perspective view showing an exploded view of a liquid crystal display module 601 which is a part of the liquid crystal display device according to the present invention. The liquid crystal display module 601 is generally viewed from the backlight assembly 500, the chassis 650, and the liquid crystal display. The liquid crystal display panel 610 is composed of the panel 610, which is the same as the parts described above with reference to FIGS. 1 to 7, and thus description thereof will be omitted and the backlight assembly 500 will be described in more detail. .

The backlight assembly 500 may further include a storage container 510 having a predetermined storage area, a reflective plate 520 accommodated on the bottom surface of the storage container 510, a light guide plate 530 seated on an upper surface of the reflective plate 520, and a light guide plate ( The lamp unit 540 coupled to the light guide plate 530 in parallel with the light guide plate 530 at one end of the thickest one of the thicknesses 530 is configured as an optical modulation device 550 installed inside the lamp unit 540.

Specifically, the light guide plate 530 has a rectangular parallelepiped shape, and the bottom surface of the light guide plate 530 is mirrored or flat, and a triangular groove 535 is formed on the bottom surface of the light guide plate 530, and the triangular groove 535 is formed in the light guide plate 530. Density is higher than the density in one side is cut toward the other side facing.

The lamp unit 540 is coupled to the side having the thickest thickness of the light guide plate 530 formed as described above, and the lamp unit 540 is radiated in all directions from the cold cathode ray tube type lamp 545 and the lamp 545. And a lamp cover 546 surrounding the lamp 545 to emit white light only toward the light guide plate 530.

An optical modulation device 550 is formed inside the lamp unit 540, and the optical modulation device 550 is distributed between the lamp cover 540 and the side surface of the light guide plate 530 and the lamp 545.

More specifically, the optical modulation device 550 is formed between the lamp cover 546 and the light guide plate 530, as shown in Figs. As the light modulating means for converting into waves, the light modulating means preferably uses Dual Brightness Enhancement Film (DBEF) 556.

Unexplained reference numeral 560 is the same inverse prism sheet as the embodiment described above.

A method of increasing the brightness of a liquid crystal display according to the present invention configured as described above will be described with reference to FIG. 10 with reference to the accompanying drawings.

First, the P- and S-waves are mixed in the white light generated by the lamp 545 to reach the DBEF 556 formed on the side of the light guide plate 530.

At this time, the DBEF 556 passes the S wave, but the P wave is modulated into the S wave while passing through the DBEF 556, so that the S and P waves generated by the lamp 545 are modulated into the S wave while passing through the DBEF 556, and then the light guide plate ( 530 is incident inside.

In this manner, the S-waves incident into the light guide plate 530 are reflected by the mirror surface and the triangular groove 535 formed on the bottom surface of the light guide plate 530, and thus the angle of about 60 to 70 ° is determined based on the top surface of the light guide plate 530. The S wave emitted through the light guide plate 530 passes through the reverse prism sheet 560 and has an angle close to a right angle with respect to the top surface of the light guide plate 530.

Subsequently, the S-wave passing through the inverted prism sheet 560 passes through the polarizing plate 614 formed on the TFT substrate 612 of the liquid crystal display panel 610 as it is, passes through the liquid crystal layer, and then the color filter substrate 616. It stimulates the user's eyes by passing through the user, as in the above-described embodiment, it is possible to recognize the display content of a predetermined image, video, still image, text, symbol, etc. in a state where the brightness is improved, but the liquid crystal display module ( The thickness of 601 can be reduced.

As described in detail above, an optical modulation device is formed inside the lamp unit, which is a component of the backlight assembly of the liquid crystal display device, thereby greatly lowering the manufacturing cost, and of course, the luminance of the lamp unit and the luminance outside the liquid crystal display panel There is an effect of greatly increasing the brightness of the outside of the liquid crystal display panel to be close to each other.

Claims (10)

A liquid crystal display panel including a TFT substrate having a first polarizing plate, a color filter substrate having a second polarizing plate, and a liquid crystal injected between the color filter substrate and the TFT substrate; A lamp disposed on a side of the liquid crystal display panel to generate white light having a mixture of first polarized light passing through the first polarizing plate and second polarized light not passing through the first polarizing plate, and covering an upper side of the lamp and an opening at a lower side thereof; A lamp unit including a lamp cover to guide the white light downward; An optical modulation device disposed below the lamp unit to reflect the first polarized light and convert the second polarized light into a first polarized light; A light guide plate facing one side of the optical modulation device and disposed below the liquid crystal display panel, for guiding the first polarized light and the converted first polarized light reflected by the optical modulation device to the first polarizing plate; And a light collecting sheet disposed between the light guide plate and the first polarizing plate. delete The optical modulator of claim 1, wherein the optical modulator has a triangular columnar first optical modulator body having the same refractive index n ₁ as the light guide plate, and a refractive index n ₂ different from that of the first optical modulator body. And a second optical modulation device body having a triangular prism shape having an inclined surface having an inclination to be butt-butted with the first optical modulation device body and two surfaces connected to the inclined surface, The first optical modulation device body includes a first side facing the lower side of the lamp and the second side facing the one side of the light guide plate and the white light is incident, the second light modulation device body is the first And a fourth side surface parallel to the side surface and a fourth side surface parallel to the second side surface. 4. The liquid crystal display of claim 3, wherein a phase difference plate and a reflecting plate are provided on the third side, and a reflecting plate is provided on the fourth side. delete delete The liquid crystal display of claim 1, wherein the light collecting sheet is a reverse prism sheet having a prism formed on a surface facing the light guide plate and having a flat surface on the other side thereof. The method of claim 1, wherein the lamp unit is disposed on one side of the light guide plate, And the optical modulation device is a dual brightness enhancement film (DBEF) disposed between the lamp unit and the light guide plate to transmit the first polarized light and change the second polarized light to the first polarized light. delete delete

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