JPH10333173A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the liquid crystal display device which can be decreased in the size of its frame part by minimizing the thermal influence of a driving integrated circuit on a liquid crystal display panel. SOLUTION: This liquid crystal display device is equipped with the liquid crystal display panel 1 constituted by charging liquid crystal between glass substrates stuck together across a gap and providing a transparent electrode for driving, a TCP(tape carrier package) fixed to the edge part of the liquid crystal display panel 1, a driver IC 2 mounted on the TCP 3, a pattern wire 17 which is formed on the TCP 3 and electrically connects the transparent electrode 13 to the driver IC 2, and a heat radiation plate 5 which is arranged abutting against the driver IC 2. The resistance value of the pattern wire 17 per unit length is less than that of the transparent electrode 13 and the heat conductivity of the pattern wire 17 is less than that of the heat radiation plate 5.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat-panel liquid crystal display device, and more particularly to a flat panel type liquid crystal display device. A possible liquid crystal display device.

[0002]

2. Description of the Related Art In general, a flat panel type liquid crystal display device has a driver IC (driving integrated circuit) arranged at an edge of a rectangular liquid crystal display panel in which liquid crystal is sealed in a glass substrate bonded at intervals. And a driver IC connected to an end of each electrode arranged in a matrix in the liquid crystal display panel. Since this driver IC switches a large number of electrodes at a high speed, a considerable amount of heat is generated. Therefore, in order to efficiently dissipate heat from the driver IC, a liquid crystal display device having a structure in which a large metal substrate is arranged on the back of the liquid crystal display panel and the driver IC is mounted on the substrate via an insulating film. Has been proposed in the past (Japanese Unexamined Patent Publication No.
No. 5584).

[0003]

However, in a display device having a structure in which a large-sized substrate of this kind is arranged on the back surface of a display panel, a heat-radiating substrate hinders use of a backlight or the like. Cannot be adopted. Therefore,
2. Description of the Related Art A display device having a structure in which a heat radiating plate is arranged in a frame at an edge of a liquid crystal display panel has been developed. In this liquid crystal display device, as shown in FIGS. 7 and 8, a TCP (tape carrier package) 33 is attached to a side edge of a liquid crystal display panel 31, a driver IC 32 is mounted on the TCP 33, and a driver IC 32 is mounted on the outside. A printed circuit board 34 is mounted, a heat radiating plate 35 is mounted thereon while being in contact with the driver IC 32, and a frame cover 36 is further mounted thereon.

In operation, the heat radiated from the driver IC 32 is radiated from the radiator plate 35,
When the amount of heat from the substrate increases, a considerable amount of heat is transmitted to the liquid crystal display panel 31 through the TCP 33 having the copper wiring pattern having good thermal conductivity.

For this reason, the temperature of the liquid crystal display panel 31 is increased. The most important problem, however, is that when the entire liquid crystal display panel is viewed, the temperature is high at the periphery of the panel and lower at the center. Temperature distribution occurs. As a result, the characteristics of the liquid crystal change according to the temperature, and there is a problem that display unevenness occurs on the display surface.

Therefore, in order to reduce the amount of heat transmitted to the liquid crystal display panel 31, the size of the heat radiating plate 35 is increased, and
Although the length of the 33 has been increased, the peripheral frame portion (frame cover portion) of the display device becomes relatively large, which causes a problem that the commercial value of the display device is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display device capable of reducing the size of a frame portion by minimizing the thermal influence of a driving integrated circuit on a liquid crystal display panel. The purpose is to provide.

[0008]

In order to achieve the above object, a liquid crystal display device of the present invention comprises a liquid crystal in which a liquid crystal is sealed in a glass substrate bonded at intervals and a transparent electrode for driving is provided. A display panel, a circuit supporting member fixed to an edge of the liquid crystal display panel, a driving integrated circuit mounted on the circuit supporting member, and an electric circuit formed on the circuit supporting member and electrically connecting the transparent electrode and the driving integrated circuit. A liquid crystal display device comprising: a current-carrying member connected to the liquid crystal display; and a heat-dissipating member disposed in contact with the drive integrated circuit, wherein the resistance per unit length of the current-carrying member is equal to the unit length of the transparent electrode. It is characterized in that the heat conduction member is formed to have a lower heat resistance than the heat resistance of the heat dissipating member.

[0009]

In the liquid crystal display device having such a configuration, during the display operation, the drive integrated circuit energizes a large number of transparent electrodes while switching and drives the display panel, thereby generating heat. Since the thermal conductivity of the member is lower than the thermal conductivity of the heat dissipating member, the heat of the integrated circuit is efficiently transmitted to the heat dissipating member side and dissipated, and the heat is transmitted to the liquid crystal display panel side through the conducting member of the circuit supporting member. It is rarely transmitted.

Therefore, there is no temperature distribution such that the temperature is higher at the periphery of the display panel and lower at the center, and it is possible to prevent the occurrence of display unevenness due to the temperature difference. Therefore, the distance from the drive integrated circuit to the display panel can be substantially reduced as compared with the conventional liquid crystal display device, so that the width of the frame portion is narrowed and the outer shape of the display device is reduced as compared with the conventional liquid crystal display device. be able to.

Further, since the resistance value per unit length of the current-carrying member is formed lower than the resistance value per unit length of the transparent electrode, it does not affect the operation of the transparent electrode at all.
Good display operation can be performed.

Further, when the current-carrying member is made of stainless steel and the heat-dissipating member is made of aluminum, it is possible to stably and electrically use a relatively inexpensive material. Further, as in claims 3 and 4, the circuit support member is a tape carrier package, and the energizing member is
If the stainless steel pattern wiring formed on the tape carrier package is used, the mounting and wiring of the driving integrated circuit can be efficiently performed in a small space.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a liquid crystal display device, and FIG. 2 is a sectional view thereof. Reference numeral 1 denotes a liquid crystal display panel formed in a rectangular thin flat plate shape, and two glass substrates 1 each having a transparent electrode 13 formed in a matrix inside.
1 and 12 are bonded in parallel with a gap therebetween, and a liquid crystal 14 is filled between the two glass substrates 11 and 12 and sealed by a sealing material 15. As the liquid crystal, for example, a ferroelectric liquid crystal such as SmC is used, and an FLC type liquid crystal display panel is obtained.

The transparent electrode 13 is formed by depositing an ITO film on the glass substrates 11 and 12 to a thickness of 5000 ° by, for example, a sputtering method, and patterning the ITO film by a photolithography method to form a matrix as a number of parallel lines. You.

The lower glass substrate 12 of the liquid crystal display panel 1
A TCP (tape carrier package) 3 is fixed as a circuit support member to an edge of the tape carrier. The TCP 3 is formed by patterning a pattern wiring (conductive member) 17 made of stainless steel on a tape-like base film 16 as shown in FIG. 3, and a driver IC (drive integrated circuit) 2 is mounted thereon.

As shown in FIGS. 3 and 4, the driver IC 2 has its terminals connected to the pattern wiring 17 via a TBA 19 (bonding portion) and molded and fixed on the TCP 3 by a molding resin 18. The thermal conductivity of the stainless steel pattern wiring 17 is about 20 W / m · K, and the copper pattern wiring (the thermal conductivity is about 400 W / m · K).
-Compared to that of K), it is considerably lower, about 1/20.

The printed circuit board 4 is fixed to the outside of the TCP 3, and the terminal of the pattern wiring 17 of the TCP 3 is connected to the connection terminal of the printed circuit board 4. The other terminal of the printed circuit board 4 is connected to a control circuit (not shown). TCP3
A heat radiating plate 5 made of aluminum is attached in contact with the upper surface of the driver IC 2 for heat radiation of the upper driver IC 2.
Aluminum has a thermal conductivity of about 200 W / m · K. The heat radiating plate 5 is formed in a frame shape and is attached so as to cover the printed circuit board 4 from the driver IC 2. Further, a frame cover 6 is mounted on the heat sink 5 so as to cover the heat sink 5.
A frame is formed.

The liquid crystal display device having the above-described structure is driven by a driver IC from a control circuit (not shown).
2 is operated to change the molecular arrangement direction of the liquid crystal in the liquid crystal display panel 1, thereby changing the liquid crystal between, for example, a light scattering state and a transparent state, and displaying a character figure or the like. During the display operation, the driver IC 2 energizes the many transparent electrodes 11 and 12 while switching, and generates heat to drive the display panel. However, the heat is transmitted to the heat radiating plate 5 and further to the frame cover 6 to be efficiently radiated, and is rarely transmitted to the liquid crystal display panel 1 via the TCP 3.

That is, as described above, the thermal conductivity of aluminum of the heat sink 5 is about 200 W / m · K, which is about 10 times that of stainless steel (about 20 W / m · K) of the pattern wiring 17. The generated heat is not easily transmitted to the TCP 3 side, is efficiently transmitted to the heat radiating plate 5, and is radiated therefrom. Therefore, the heat of the driver IC 2 is not easily transmitted to the liquid crystal display panel 1 side, and the occurrence of display unevenness due to the temperature distribution due to the heat is prevented.

The ITO film used for the transparent electrode 13 has, for example, a width of 250 μm, a thickness of 0.4 μm, a resistance value per unit length of 15.6 kΩ / m, and a transparent electrode 1.
When the length of the transparent electrode 13 is, for example, 360 mm, the resistance value of the transparent electrode 13 is 5.6 kΩ. Further, in order to reduce the resistance value of the transparent electrode 13, a metal wiring with a small line width (resistance value 70) is used.
0 Ω), the total resistance value of the transparent electrode 13 per unit length is 1.9 kΩ / m.

On the other hand, the stainless steel pattern wiring 17 used in the TCP 3 has a width of 250 mm because the stainless steel has a volume resistivity of 10 to 20 × 10 ⁻⁸ Ω · m.
When the thickness is 20 μm and the thickness is 20 μm, the resistance value per unit length is 20 to 40 Ω / m, and this resistance value is about 1/47 to about 1/47 of the resistance value of the transparent electrode 13 of 1.9 kΩ / m. 95
Even if stainless steel is used for the pattern wiring, there is no problem in the operation of the transparent electrode 13.

As described above, since the heat of the driver IC 2 is efficiently radiated from the radiator plate 5 and is not easily transmitted to the liquid crystal display panel 1 via the TCP 3, the distance from the driver IC 2 to the display panel 1 in FIG. L) can be substantially shortened. This makes it possible to make the width of the frame narrower than that of the conventional liquid crystal display device (FIG. 8), and to reduce the outer shape of the display device.

Next, an experimental example performed to confirm the above effects will be described with reference to FIGS. In the experimental configuration, as shown in FIG. 5, a metal foil (aluminum foil or stainless steel foil) 23 was fixed on a small heater 21 via a heat conductive tape 22, and the temperature of the heater 21 was heated to 100 ° C. The temperature at the tip of the metal foil 23 was measured. As the metal foil 23, a thickness of 20 μm, a width of 16 mm, and a length (0.01 m to
The above experiment was performed using a plurality of aluminum foils and stainless steel foils having different thicknesses of 0.05 m), and a result of temperature rise ΔT with respect to a change in the length of the metal foil as shown in FIG. 6 was obtained.

From the experimental results shown in the graph of FIG. 6, the case where the length of the metal foil 23 is L = 0.01 m is examined. Tip temperature is 1 for foil
Stays at 0 ° C. In addition, it can be seen that the length of the tip of the aluminum foil must be at least three times longer than that of the stainless steel foil in order to suppress the rise in temperature to 10 ° C.

Therefore, considering that the thermal conductivity of the copper foil used for the conventional TCP is about twice that of aluminum, changing the pattern wiring of TCP3 from copper to stainless steel further increases the driver IC. Heat can be efficiently transmitted to the heat radiating plate, and the width of the frame portion of the display device can be significantly reduced without affecting the display panel.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view taken along the line II-II of FIG.

FIG. 3 is a partial plan view of TCP.

FIG. 4 is a partially enlarged sectional view of TCP.

FIG. 5 is an experimental configuration diagram of an experimental example.

FIG. 6 is a graph showing experimental results of an experimental example.

FIG. 7 is a perspective view of a conventional liquid crystal display device.

FIG. 8 is an enlarged sectional view taken along the line VIII-VIII in FIG. 7;

[Explanation of symbols]

 1-Liquid crystal display panel 2-Driver IC (Drive integrated circuit) 3-TCP (Circuit support member) 5-Heat radiator 11, 12-Glass substrate 13-Transparent electrode 14-Liquid crystal 17-Pattern wiring

Claims (4)

[Claims] 1. A liquid crystal display panel in which liquid crystal is sealed in a glass substrate bonded at intervals and a driving transparent electrode is provided; a circuit support member fixed to an edge of the liquid crystal display panel; A drive integrated circuit mounted on the circuit support member; a current-carrying member formed on the circuit support member for electrically connecting the transparent electrode and the drive integrated circuit; A heat dissipating member provided, wherein the resistance value per unit length of the current-carrying member is lower than the resistance value per unit length of the transparent electrode; A liquid crystal display device wherein the conductivity is lower than the heat conductivity of the heat radiating member. 2. The liquid crystal display device according to claim 1, wherein said conductive member is formed of stainless steel, and said heat radiating member is formed of aluminum. 3. The tape carrier according to claim 1, wherein the circuit supporting member is a tape carrier.
3. The liquid crystal display device according to claim 1, comprising a package. 4. The tape carrier according to claim 1, wherein
3. The liquid crystal display device according to claim 2, wherein the liquid crystal display device is a pattern wiring made of stainless steel formed on the package.