KR100708843B1 - LCD with improved low temperature characteristics and brightness - Google Patents

Abstract

The present invention relates to a liquid crystal display device having improved low temperature characteristics and luminance. To this end, the liquid crystal display device according to the present invention includes a liquid crystal display panel for displaying an image, and a backlight unit including a light source for supplying light to the liquid crystal display panel and a part of the side surface of which is surrounded by a metal film. The present invention can smoothly drive while increasing the light efficiency of the liquid crystal display device.

LCD, Liquid Crystal, Time Division, Light Emitting Diode, Mold Frame

Description

Liquid crystal display with improved low temperature characteristics and brightness {A LIQUID CRYSTAL DISPLAY DEVICE IMPROVING LOW TEMPERATURE PROPERTY AND LUMINESCENCE}

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

2 is a perspective view illustrating a liquid crystal display according to an exemplary embodiment of the present invention.

3 is a partial cross-sectional view taken along line AA of FIG. 2.

The present invention relates to a liquid crystal display device having improved low temperature characteristics and brightness, and more particularly, to a liquid crystal display device having improved low temperature characteristics and brightness by forming a metal film on a part of the side surface of the backlight assembly.

With the recent development of semiconductor technology, which is rapidly developing in recent years, the demand for flat panel display devices that are smaller and lighter and has improved performance is exploding.

The liquid crystal display (LCD), which has recently been in the spotlight among the flat panel display devices, has advantages such as miniaturization, light weight, and low power consumption, thereby overcoming the disadvantages of the conventional cathode ray tube (CRT). It has been attracting attention as an alternative means, and now it is being installed and used in small and medium-sized monitors and TVs as well as mobile phones and PDAs (portable digital assistor) which require a flat panel display device.

A general liquid crystal display device applies voltage to a specific molecular array of a liquid crystal to convert it into another molecular array, and visually changes optical properties such as birefringence, photoreactivity, dichroism, and light scattering characteristics of the liquid crystal cell emitted by the molecular array It is a display device which displays information using modulation of the light by a liquid crystal cell as converting into a change.

Since the liquid crystal display is a light receiving element that cannot emit light by itself, the liquid crystal display includes a backlight assembly that guides the light emitted from the light source and improves the brightness thereof. Phenomenon occurs. Accordingly, since the amount of light supplied to the liquid crystal display panel is reduced, it is difficult to display the image clearly.

On the other hand, a method of displaying an image by receiving light from a liquid crystal display device is largely divided into two methods, a color filter method and a field sequential driving method.

In the case of the color filter method, a color filter layer consisting of three primary colors of red (R), green (G), and blue (B) is formed on one of two substrates constituting the liquid crystal display panel, and is transmitted through the color filter layer. Adjust the amount of light to display the desired color. In the color filter type liquid crystal display device, when light emitted from a single light source is transmitted to a color filter layer made of RGB, a desired color may be displayed by adjusting the amount of light transmitted through the color filter layer to synthesize RGB colors.

As described above, in a liquid crystal display device displaying color using a single light source and a color filter layer composed of RGB, unit pixels corresponding to respective RGB areas are required, so that three times as many pixels are required as in the case of displaying black and white. Therefore, in order to obtain a high resolution image, the color filter layer must be precisely formed on the liquid crystal display panel, which leads to a complicated manufacturing process and an improvement in the light transmittance of the color filter itself.

On the other hand, a field sequential (FS) type liquid crystal display device sequentially turns on independent light sources of RGB colors, and displays a full color image by applying a color signal corresponding to each pixel in synchronization with the lighting cycle. . That is, in the field sequential driving method, an afterimage effect of the eyes is displayed in image display by sequentially dividing light of RGB primary colors output from the RGB backlight into one pixel without dividing one pixel into unit pixels of RGB. I use it.

In the field sequential driving system as described above, an image must be displayed by time-dividing and supplying light, so that several frames must be driven within a short time. Therefore, the liquid crystal molecules positioned inside a specific pixel are required to respond quickly while forming the next frame by rapidly changing the twist angle according to the change of the applied voltage after one frame driving. However, the liquid crystal is affected by temperature as a mixed state of a solid phase and a liquid phase, and in particular, as the temperature decreases, the response characteristic of the liquid crystal is remarkably lowered, and thus the frame does not change rapidly. Therefore, the liquid crystal display of the field sequential driving method significantly reduces the display characteristics in a low temperature environment, thereby limiting its function as a display device.

 SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and to provide a liquid crystal display device having a low temperature characteristic and brightness by forming a metal film on a part of a side surface of the backlight assembly.

A liquid crystal display according to the present invention includes a liquid crystal display panel for displaying an image, and a backlight assembly including a light source for supplying light to the liquid crystal display panel, the side of which is surrounded by a metal film.

The liquid crystal display according to the present invention further includes a mold frame accommodating the liquid crystal display panel and the backlight assembly, and a metal film may be formed on an inner surface of the mold frame.

It is preferable that a reflective layer is formed on the surface of the metal film adjacent to the liquid crystal display panel and the backlight assembly.

Here, the reflective layer may be made of silver (Ag).

The metal film is externally connected and heated, and heat of the heated metal film is transferred to the liquid crystal display panel.

The light source may be a light emitting diode (LED), and the light emitting diode may time-divide and emit light.

The liquid crystal display panel includes a first substrate, a second substrate facing the first substrate and having a plurality of thin film transistors (TFTs) formed therein, and a liquid crystal injected between the first substrate and the second substrate, and heated. It is preferable that the heat of the metal film is transferred to the liquid crystal.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 3. These embodiments of the present invention are merely for illustrating the present invention, but the present invention is not limited thereto.

1 is an exploded perspective view of a liquid crystal display device 100 according to an exemplary embodiment of the present invention, in which all parts included in the liquid crystal display device 100 are disassembled and shown.

The liquid crystal display device 100 according to the first exemplary embodiment of the present invention shown in FIG. 1 includes a backlight assembly 40 for supplying light and a liquid crystal display panel 75 for displaying an image by receiving light. . In addition, a top chassis 60, a mold frame 62, and a bottom chassis 66 are included to fix and support them.

The liquid crystal display panel assembly 70 includes a liquid crystal display panel 75, an integrated circuit chip (IC chip) 77, and a flexible printed circuit board (FPC board) 79. . In order to protect the integrated circuit chip 77, a protective film 78 is coated around the integrated circuit chip 77.

The liquid crystal display panel 75 includes a first substrate 71, a second substrate 73, and a liquid crystal (not shown) injected therebetween. The second substrate 73 is a TFT (thin film transistor) substrate facing the first substrate 71, and a plurality of TFTs are formed. The second substrate 73 is a transparent glass substrate in which TFTs are formed in a matrix, and a data line is connected to a source terminal and a gate line is connected to a gate terminal. A pixel electrode made of transparent indium tin oxide (ITO) as a conductive material is formed on the drain terminal.

The data line and the gate line of the liquid crystal display panel 75 described above are connected to the flexible printed circuit board 79, and when an electrical signal is input from the flexible printed circuit board 79, the data line and the gate line are electrically connected to the source terminal and the gate terminal of the TFT. An input signal is input, and the TFT is turned on or off in accordance with the input of these electrical signals, and an electrical signal necessary for pixel formation is output to the drain terminal. The integrated circuit chip 77 is mounted on the second substrate 73 to control the liquid crystal display panel 75. The integrated circuit chip 77 generates a data signal, a gate driving signal, which is a signal for driving the liquid crystal display device 100, and a plurality of timing signals for applying these signals at an appropriate time, and generates a gate driving signal and data driving. The signal is applied to the gate line and the data line of the liquid crystal display panel 75, respectively.

On the other hand, a common electrode made of ITO is coated on the entire surface of the first substrate 71 disposed on and facing the second substrate 73. When driving the liquid crystal display device 100 by the color filter method, the first substrate 71 is formed of a color filter substrate on which RGB pixels are formed. When power is applied to the gate terminal and the source terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. The arrangement angle of the liquid crystal injected between the first substrate 73 and the second substrate 71 is changed by the electric field, and the light transmittance is changed according to the changed arrangement angle to obtain a desired pixel. Polarizers (not shown) are attached to the surfaces of the first substrate 73 and the second substrate 71 to polarize the light.

The lower portion of the liquid crystal display panel assembly 70 is provided with a backlight assembly 40 that provides uniform light to the liquid crystal display panel 75 and is mounted on the bottom chassis 66.

The backlight assembly 40 is fixed to the mold frame 62, and the substrate 43 on which one or more light emitting diodes 41 (dotted lines) supply light to the liquid crystal display panel 75 and the light emitting diodes 41 are mounted. The light guide plate 10, which guides the light emitted from the light emitting diode 41 and supplies the light to the liquid crystal display panel 75, is positioned on the lower front surface of the light guide plate 10 to direct the light emitted from the light source toward the liquid crystal display panel 75. A reflective sheet 46 for reflecting, and an optical sheet 48 for supplying light to the liquid crystal display panel 75 by securing the luminance characteristics of the light from the light emitting diode 41. Although the number of light emitting diodes 41 is shown in three in FIG. 1, this is merely to illustrate the present invention and the present invention is not limited thereto. Therefore, the number of light emitting diodes 41 may be different.

Although not shown in FIG. 1, a bottom surface of the bottom chassis 66 is provided with a printed circuit board (not shown) connected to the flexible printed circuit board 79 to convert an analog data signal into a digital data signal, and then a liquid crystal display panel. Supply to (75). In addition, the printed circuit board (not shown) is connected to the substrate 43 and the wiring 42 to supply power to the light emitting diode 41.

The liquid crystal display 100 may be driven by a color filter driving method or a field sequential driving method. When driving the liquid crystal display device 100 in a field sequential driving method, each of the light emitting diodes 41 may emit all three colors of RGB, and a printed circuit board (not shown) located below the bottom chassis 66. ) Receives a driving signal according to the field sequential driving method and time-division emits light. By displaying all colors using the RGB tri-color emitted by time division, a clear image is realized on the liquid crystal display panel 75.

The top chassis 60 is provided on the liquid crystal display panel assembly 70, and the liquid crystal display panel assembly 70 is separated from the bottom chassis 66 while bending the flexible printed circuit board 79 to the outside of the mold frame 62. Prevent it.

A portion of the side surface of the backlight assembly 40 is surrounded by the metal film 621 to prevent light from leaking from the backlight assembly 40. Since the substrate 43 and the like included in the backlight assembly 40 protrude to the outside for power connection, it is difficult to surround all of the side surfaces of the backlight assembly 40 with the metal film 621. Accordingly, a part of the side surface of the backlight assembly 40 may be surrounded by the metal film 621 to prevent light leakage. In FIG. 1, a metal film 621 is formed on an inner surface of the mold frame 62 to surround a portion of the side surface of the backlight assembly 40 with the metal film 621. However, such a method of forming the metal film 621 is merely for illustrating the present invention, the present invention is not limited thereto. Therefore, the metal film can also be formed by other methods.

FIG. 2 is a combined perspective view of a liquid crystal display device 100 according to an exemplary embodiment of the present invention, in which all internal components of the liquid crystal display device 100 shown in FIG. 1 are combined. An image is displayed on the liquid crystal display panel 75 using the light emitted from the light emitting diode 41 shown in FIG. In particular, the liquid crystal display 100 may minimize light leaking by enclosing a part of the side surface of the backlight assembly with a metal film, thereby realizing a clearer image.

3 is a partial cross-sectional view taken along the line AA of FIG. 2 and shows an internal structure of the liquid crystal display device 100.

As indicated by the arrows in FIG. 3, the light exiting to the outside is reflected again by using the metal film 621, thereby increasing the light utilization efficiency. In particular, a reflective layer may be formed on the surfaces of the liquid crystal display panel 75 and the metal film 621 adjacent to the backlight assembly to increase light utilization efficiency. The reflective layer may be made of silver (Ag) having excellent light reflectance. By applying silver to the surface of the metal film 621 as described above, light can be minimized from escaping to the outside of the liquid crystal display, thereby realizing a clear image.

On the other hand, in the case of the liquid crystal display device or the like driven by the field sequential driving method, it is necessary to maintain the liquid crystal display panel 75 at a constant temperature so that the operation characteristics of the liquid crystal are good. In particular, since the operating characteristics of the liquid crystal molecules are deteriorated at a low temperature of 0 ° C. or lower, the metal film 621 is externally connected and heated to prevent this. The heat of the heated metal film 621 is transferred to the liquid crystal display panel 75. The heat transferred to the liquid crystal display panel 75 is also transferred to the liquid crystal, so that the liquid crystal can move smoothly, thereby operating characteristics are good.

To this end, the metal film 621 is connected to an external power source through the connection wiring 623. When a voltage is applied to the metal film 621 through an external power source, the metal film 621 is heated due to the self resistance of the metal film 621. Since the method of connecting the power source can be easily understood by those skilled in the art, detailed description thereof will be omitted.

The heat emitted from the heated metal film 621 is transferred to the liquid crystal molecules injected into the liquid crystal display panel 75 as shown by arrows in FIG. 3. Accordingly, in the case of the field sequential driving type liquid crystal display device that needs to display a large number of frames within a short time, the operation characteristics of the liquid crystal molecules are excellent and a clear screen can be realized.

As described above, in the liquid crystal display device according to the present invention, since a part of the side surface of the backlight assembly is surrounded by the metal film, light leaking to the outside can be minimized, thereby improving the light efficiency.

Since the metal film can be formed on the inner surface of the mold frame, there is an advantage in that the metal film is more easily formed.

A reflective layer may be formed on the surface of the metal film to optimize light efficiency in the backlight assembly.

In particular, the reflection layer may be formed of silver to further increase the reflection efficiency.

By heating the metal film by external connection and transferring the heat to the liquid crystal display panel, the liquid crystal display device driven by the field sequential driving method can be smoothly driven.

The present invention can be simply applied to a liquid crystal display device in which a light emitting diode time-divids and emits light to apply a field sequential driving method.

The heat of the heated metal film is transferred to the liquid crystal injected into the liquid crystal display, so that the operating characteristics of the liquid crystal molecules can be maintained well even in a low temperature environment of 0 ° C or less.

Although the present invention has been described above, it will be readily understood by those skilled in the art that various modifications and variations are possible without departing from the spirit and scope of the claims set out below.

Claims (7)

A liquid crystal display panel displaying an image, and A backlight unit including a light source for supplying light to the liquid crystal display panel and surrounded by a metal film formed on a side surface thereof Including, The backlight unit further comprises a light guide plate for supplying light emitted from the light source to the liquid crystal display panel, wherein the metal film is adjacent to the side of the light guide plate to transfer heat to the liquid crystal display panel. In claim 1, And a mold frame accommodating the liquid crystal display panel and the backlight unit, wherein the metal film is formed on an inner surface of the mold frame. In claim 1, And a reflective layer formed on a surface of the metal film adjacent to the liquid crystal display panel and the backlight unit. In claim 3, The reflective layer is made of silver (Ag). In claim 1, And the metal film is externally connected and heated, and the heat of the heated metal film is transferred to the liquid crystal display panel. In claim 5, The light source is a light emitting diode (LED), the light emitting diode is a liquid crystal display device which emits light by time division. In claim 5, The liquid crystal display panel, First substrate, A second substrate facing the first substrate and having a plurality of thin film transistors (TFTs) formed thereon, and Liquid crystal injected between the first substrate and the second substrate Including, And a heat of the heated metal film is transferred to the liquid crystal.

Images