KR20050093882A - Liquid crystal display for reducing noise - Google Patents

Abstract

The present invention relates to a liquid crystal display device which reduces noise by forming slits on one surface of a frame mold side. To this end, the liquid crystal display device of the present invention includes a liquid crystal display panel assembly in which an image is displayed, a plurality of lamps for supplying light to the liquid crystal display panel assembly, and a backlight assembly for improving brightness while guiding the light. It includes a bottom chassis for receiving a backlight assembly, characterized in that it has a frame mold side which is positioned at both ends of the plurality of lamps, respectively, and fixed to support the plurality of lamps and a slit is formed on one surface thereof. Through this invention it is possible to reduce the noise generated by the parts of the material having a different thermal expansion coefficient.

Description

Liquid Crystal Display with Reduced Noise {LIQUID CRYSTAL DISPLAY FOR REDUCING NOISE}

The present invention relates to a liquid crystal display device having reduced noise, and more particularly, to a liquid crystal display device having reduced noise by forming slits on one surface of a frame mold side.

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). As an alternative means, it has been gradually attracting attention, and is currently used in almost all information processing equipment that requires a 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 apparatus which displays information using the modulation of the light by a liquid crystal cell as converting into a change.

Since the liquid crystal display panel in the liquid crystal display device does not emit light by itself, the liquid crystal display panel includes a backlight assembly for providing light to the liquid crystal display panel under the liquid crystal display panel. In structural terms, the backlight assembly includes lamps, light guide plates, reflecting plates, optical sheets, and the like. The lamp uses a cold cathode ray tube lamp that generates relatively little heat, generates white light close to natural light, and has a long lifespan.

However, in recent years, as the liquid crystal display device gradually increases in size according to consumer's preference and is used in a large TV, a large number of lamps are installed to realize an image having sufficient luminance characteristics. Therefore, the backlight assembly of the large liquid crystal display generates a lot of heat energy due to the increased heat source. Affected by this, various parts located at the periphery of lamps having different thermal expansion rates have different degrees of expansion and contraction.

Therefore, when the power supply of the liquid crystal display is turned on and off, the heat shrinkage and thermal expansion degree of the components made of different materials are different from each other. There is a problem that the durability is weakened. This occurs especially between metal parts such as a bottom chassis and resin parts such as a mold frame, and since the thermal expansion coefficient difference between these parts is large, noise is severely generated when they are adjacent to each other.

The present invention is to solve the above-described problems, to reduce the noise generated by modifying the shape of the frame mold side for holding the lamp adjacent to the bottom chassis.

According to an exemplary embodiment of the present invention, a liquid crystal display device includes a liquid crystal display panel assembly in which an image is displayed, a plurality of lamps supplying light to the liquid crystal display panel assembly, and improves brightness while guiding the light. A backlight assembly, and a bottom chassis for receiving the backlight assembly, each of which is positioned at both ends of the plurality of lamps to fix and support the plurality of lamps, and to have a slit on one surface thereof. It is characterized by including the formed frame mold side (frame mold side).

Here, the slits are preferably formed along the longitudinal direction of the frame mold side.

In addition, the slit is preferably formed to extend in a direction perpendicular to the longitudinal direction of the frame mold side.

The frame mold side may be fixed by being screwed onto the bottom chassis.

In addition, the slit may be formed between the position where the screw is fastened.

The frame mold side may be accommodated on the bottom chassis, and one end of the slit may be open to a surface side of the frame mold side accommodated on the bottom chassis.

On the other hand, it is preferable that the said slit is formed in the surface which the said frame mold side contact | connects the side part of the said bottom chassis.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 5. 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 according to an exemplary embodiment of the present invention.

The liquid crystal display device 100 according to the first exemplary embodiment of the present invention shown in FIG. 1 includes a direct backlight assembly 20 for supplying light and a liquid crystal display panel for displaying an image corresponding to light. Assembly 50. In addition, the top chassis 60, the mold frame 30 and the bottom chassis 10 are coupled to support them fixedly. The direct backlight assembly shown in FIG. 1 is merely for illustrating the present invention, and the present invention is not limited to this structure. Accordingly, the present invention can also be applied to liquid crystal displays having other structures. The backlight assembly 20 supplies light to the liquid crystal display panel assembly 50, improves brightness while guiding the light, and the liquid crystal display panel assembly 50 positioned on the backlight assembly 20 is a liquid crystal in which an image is displayed. The display panel 40 is controlled.

The liquid crystal display panel assembly 50 includes a liquid crystal display panel 40, a tape carrier package (TCP) 51 and 53, and a printed circuit board 55 and 57. Here, the liquid crystal display panel 40 is injected between the TFT substrate 42 composed of a plurality of TFTs (thin film transistors), the color filter substrate 44 positioned on the TFT substrate 42, and the substrates. It is made of liquid crystal (not shown).

The TFT substrate 42 is a transparent glass substrate on which a matrix thin film transistor is formed. A data line is connected to a source terminal, and a gate line is connected to a gate terminal. In the drain terminal, a pixel electrode made of transparent indium tin oxide (ITO) as a conductive material is formed.

When electrical signals are input from the printed circuit boards 55 and 57 to the data lines and the gate lines of the liquid crystal display panel 40 described above, electrical signals are input to the source and gate terminals of the TFT, Depending on the input, the TFT is turned on or turned off so that an electrical signal necessary for pixel formation is output to the drain terminal.

On the other hand, a color filter substrate 44 is disposed thereon opposite the TFT substrate 42. The color filter substrate 44 is a substrate in which RGB pixels, which are color pixels in which a predetermined color is expressed while light passes, are formed by a thin film process, and a common electrode made of ITO is coated on the entire surface thereof. When power is applied to the gate terminal and the source terminal of the TFT and the thin film transistor is turned on, an electric field is formed between the pixel electrode and the common electrode of the color filter substrate. By this electric field, the arrangement angle of the liquid crystal injected between the TFT substrate 42 and the color filter substrate 44 is changed, and the light transmittance is changed according to the changed arrangement angle to obtain a desired pixel.

In order to control the alignment angle of the liquid crystals of the liquid crystal display panel 40 and the timing at which the liquid crystals are arranged, a driving signal and a timing signal are applied to the gate line and the data line of the TFT. The data driving signal is applied to the source side of the liquid crystal display panel 40. A data TCP 51 for determining the application timing of the data is attached, and a gate TCP 53 is attached to the gate side for determining the application timing of the gate driving signal.

The data PCB 55 and the gate PCB 57 for receiving a video signal from the outside of the liquid crystal display panel 40 and applying driving signals to the data line and the gate line, respectively, are provided on the gate line side of the liquid crystal display panel 40. Connection is made with the gate TCP 53 and the data TCP 51 on the data line side, respectively.

The data PCB 55 and the gate PCB 57 generate data signals, gate driving signals, which are signals for driving the liquid crystal display device 100, and a plurality of timing signals for applying these signals at appropriate times, respectively. The gate driving signal is applied to the gate line of the liquid crystal display panel 40 through the gate TCP 53, and the data signal is applied to the data line of the liquid crystal display panel 40 through the data TCP 51.

The backlight assembly 20 is provided under the liquid crystal display panel assembly 50 to provide uniform light to the liquid crystal display panel assembly 50.

The backlight assembly 20 is accommodated and fixed on the bottom chassis 10. The backlight assembly 20 includes a plurality of backlights 26 and a lower front surface of the lamp 26, which are installed on the bottom chassis 10 at a predetermined distance. A reflective sheet 27 positioned to reflect light emitted from the lamp, a frame mold side 24 positioned at both ends of the plurality of lamps 26 to hold and support the plurality of lamps 26, and a lamp 26 An optical sheet 22 and a diffusion plate 23 are provided for securing the luminance characteristic of the light from the light source and providing the light to the liquid crystal display panel assembly 50.

The frame mold side 24 shown in FIG. 1 is shown as having a total of four, two each of the upper and lower ends of the lamp. The number of such frame mold sides 24 is merely to illustrate the present invention, but the present invention is not limited thereto.

Although not shown in FIG. 1, an inverter board, which is a power supply PCB, and a signal conversion PCB are installed on the bottom of the bottom chassis 10. The inverter board transforms an external power supply to a constant voltage level to provide the lamp 26, and the signal conversion PCB is connected to the aforementioned data PCB 55 and the gate PCB 57 to convert analog data signals into digital data signals. To the liquid crystal display panel 40.

On the liquid crystal display panel assembly 50, the data PCB 55 and the gate PCB 57 are bent out of the mold frame 30 to prevent the liquid crystal display panel assembly 50 from being separated from the bottom chassis 10. A top chassis 60 is provided. Although not shown in FIG. 1, a front case and a rear case are positioned at an upper portion of the top chassis 60 and a lower portion of the bottom chassis 10, respectively, to form a liquid crystal display device 100 by combining them.

Hereinafter, the frame mold side of the present invention will be described in more detail with reference to FIGS. 2 and 3.

FIG. 2 is a partially exploded perspective view of a backlight assembly according to an exemplary embodiment of the present invention as shown in the lower part of FIG. 1, wherein the frame mold side 24 is screwed to the bottom chassis 10 on which the reflective sheet 27 is placed. 29) shows a state that is fastened and fixed. The lamp 26 is omitted for convenience.

As shown in FIG. 2, a slit 242 is formed on one surface of the frame mold side 24. A plurality of slits 242 are formed along the longitudinal direction of the frame mold side 24 to provide free space due to thermal contraction and thermal expansion of the frame mold side 24 due to heat generated from the lamp 26 (shown in FIG. 1). Secure. In addition, since the slit 242 is formed by extending in a direction perpendicular to the longitudinal direction of the frame mold side 24, a free space due to thermal expansion and thermal contraction of the frame mold side 24 in the longitudinal direction may be sufficiently secured.

In particular, the frame mold side 24 is fastened and fixed to the bottom chassis 10 with screws 29 in order to secure the durability inside the liquid crystal display device to secure durability and prevent device abnormality.

3 is a partial cutaway view of a backlight assembly according to an embodiment of the present invention, in which the frame mold side 24 is screwed onto the bottom chassis 10 with an enlarged portion shown in FIG. It is a figure which shows the state which fastened and fixed. The frame mold side 24 is accommodated on the bottom chassis 10 and fixedly fastened with a screw 29 while contacting one side of the bottom chassis 10. In FIG. 3, a portion of the side surface 102 of the bottom chassis 10 is cut away to observe the slit 242 formed on the frame mold side 24.

The frame mold side 24 shown in FIG. 3 has a much higher thermal expansion coefficient than the bottom chassis 10. For example, in the case of resin LB-1090H used as the frame mold side 24, the coefficient of thermal expansion is 60.0 × 10 ⁻⁶ / ° C., whereas in the case of Al 5052 made of aluminum used as the bottom chassis 10, the coefficient of thermal expansion Is smaller than the frame mold side 24 on the order of 23.8 × 10 ⁻⁶ / ° C. FIG.

Therefore, when the power is turned on and the power is turned off, noise due to the difference in thermal expansion rate is generated at the junction between the two shown in FIG. Offset to reduce noise. For example, said joining site | part can mention a screw fastening site | part and a side adjacent part.

In particular, since a lot of noise is generated according to the difference in thermal expansion rate at the portion fastened and fixed with the screw 29, a slit 242 is formed between the fastened and fixed position with the screw 29, as shown by the arrow of Figure 3 thermal expansion and Noise is minimized by easily freeing space due to heat shrinkage.

As shown in FIG. 3, in the present invention, one end of the slit 242 is open to the surface side of the frame mold side 24 accommodated in the bottom chassis 10. Thereby, the slit 242 can be easily formed in the frame mold side 24, and there exists an advantage that a component processing process is easy.

On the other hand, since the slit 242 is formed on the surface in which the frame mold side 24 is in contact with the side portion 102 of the bottom chassis 10, the slit 242 is used to heat the inner mold of the frame mold side 24 generated by the lamp. It can be released through the side portion 102 has the advantage that the heat dissipation effect is further improved.

Hereinafter, an experimental example of measuring noise generated when the power is turned on and the power is turned off through the liquid crystal display according to the exemplary embodiment of the present invention will be described. These experimental examples are only for illustrating the present invention, and the present invention is not limited thereto.

Experimental Example

For the liquid crystal display, noise was measured for 90 minutes after the power was turned on and for 90 minutes after the power was turned off using the SC-30 type 1 noise measuring device of CESVA. The ambient noise was less than 18dB and the noise was measured by placing the noise meter at 50cm rear of the LCD.

Experimental Example of the Invention

For the experiment of the present invention, the liquid crystal display device of the present invention was manufactured using the frame mold side LTA460H1-L01 having four slits formed on one surface along the length direction at arbitrary intervals.

Conventional Comparative Example

For comparison with the present invention, a liquid crystal display using a frame mold side in which no slit was formed was prepared as a comparative example.

As a result of the experiment of the present invention, graphs of noise generation generated over time are shown in FIGS. 4 and 5.

4 (A) and (B) are noise generation graphs in the power-on state and the power-off state according to the experimental example of the present invention, respectively, and FIGS. 5A and 5B each show a conventional comparative example. This is a graph of noise generated during power on and power off.

As can be seen by comparing FIG. 4 and FIG. 5, the noise of the present invention is greatly reduced as compared with the related art. As can be seen from Figs. 4 and 5, it can be seen that the occurrence of noise is more severe when the thermal expansion after the power is turned on than when the thermal contraction after the power is turned off.

First, in the noise measurement result for 90 minutes after the power is turned on, it can be seen that the generation of noise is significantly reduced when comparing with FIG. 4A and FIG. 5A. That is, in the case of the experimental example of the present invention, the noise exceeding 45dB during the 90 minutes after the power-on only about 6 times, in the case of the comparative example it can be seen that the noise exceeding 45dB more than 30 times. Therefore, in the power-on state, it can be seen that the present invention significantly reduces noise as compared with the conventional case.

In addition, in the noise measurement results for 90 minutes after the power is turned off, when comparing with FIG. 4 (B) and FIG. 5 (B), the noise generation was significantly reduced as in the noise measurement result for 90 minutes after the power was turned on. Able to know. In the case of the experimental example of the present invention, the noise of more than 45dB during the 90 minutes after the power OFF only about three times, in the case of the comparative example it can be seen that the noise of more than 45dB occurs seven times. Therefore, even in the power-off state, it can be seen that the noise is significantly reduced in the case of the present invention compared with the prior art.

As described above, the liquid crystal display according to the present invention includes a frame mold side having slits formed on one surface thereof, and thus a free space due to thermal expansion and thermal contraction of the frame mold side can be secured, thereby preventing the power supply from being turned on and off. Can reduce the generation of noise.

In addition, since a plurality of slits are formed along the longitudinal direction of the frame mold side, the slits are more effective in reducing noise generated due to severe thermal expansion and thermal contraction in the longitudinal direction.

In addition, since the slit is formed by extending in a direction perpendicular to the longitudinal direction of the frame mold side, it is possible to sufficiently secure a free space due to thermal expansion and thermal contraction in the longitudinal direction of the frame mold side, thereby making it easier to prevent noise.

In particular, since the frame mold side is fastened by being screwed onto the bottom chassis, it is possible to prevent the degradation of durability such as isolation between adjacent parts caused by the difference in thermal expansion rate with the bottom chassis.

In addition, the slit is formed between the position where the screw is fastened and fixed, so that even if the frame mold side having a larger thermal expansion rate than the bottom chassis is thermally expanded or thermally contracted, a free space can be secured accordingly. There is an advantage to prevent the occurrence.

 In addition, since one end of the slit is formed to have a shape in which the frame mold side is received on the bottom chassis and is open to the surface side, the slit can be more easily formed on the frame mold side, thereby facilitating a component processing process.

In addition, since the frame mold side forms a slit on a surface of the bottom chassis in contact with the side of the bottom chassis, the heat generated by the lamp can be discharged through the side of the bottom chassis, so that the heat dissipation effect is further improved.

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.

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

2 is a partially exploded perspective view of a backlight assembly according to an exemplary embodiment of the present invention.

3 is a partial cutaway view of a backlight assembly according to an embodiment of the present invention.

4 (A) and (B) are noise generation graphs in the power ON state and the power OFF state, respectively, according to the experimental example of the present invention.

5A and 5B are noise generation graphs in a power ON state and a power OFF state, respectively, according to a conventional comparative example.

Claims (7)

Liquid crystal display panel assembly, A backlight assembly including a plurality of lamps for supplying light to the liquid crystal display panel assembly, the backlight assembly improving brightness while guiding the light; A bottom chassis for housing the backlight assembly Including, And a frame mold side positioned at both ends of each of the plurality of lamps to fix and support the plurality of lamps, and having a slit formed on one surface thereof. In claim 1, The plurality of slits are formed along the longitudinal direction of the frame mold side. In claim 2, And wherein the slit extends in a direction perpendicular to a length direction of the frame mold side. In claim 1, And the frame mold side is fixed to the bottom chassis by screwing. In claim 4, The slit is formed between the position where the screw is fastened and fixed. In claim 1, And the frame mold side is received on the bottom chassis, and one end of the slit is open to a surface side of the frame mold side received and contacted on the bottom chassis. In claim 1, And the slit is formed on a surface of the frame mold side in contact with a side portion of the bottom chassis.