JPH05313184A - External circuit structure for driving liquid crystal display elements - Google Patents

Abstract

(57) [Summary] [Structure] Liquid crystal driving manufactured by the TAB method in which a semiconductor chip is mounted on a film carrier having a conductor lead on an electrode terminal extending around the lower glass substrate of a liquid crystal display device and then individually separated. The semiconductor device for connection is connected using an anisotropic conductive adhesive film, the printed circuit board for supplying an input signal for operating the semiconductor chip and the film carrier are connected by soldering, and the heat dissipation member 6 is connected to the semiconductor chip portion from the upper surface of the display surface. An external circuit structure for driving the liquid crystal device, which is installed so as to be located at the bottom. [Effect] The temperature rise of the semiconductor device is suppressed, the life of the semiconductor chip is extended, and the reliability is improved. Further, the heat effect of the semiconductor device on the liquid crystal display element can be reduced, and a liquid crystal display element with a larger screen can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a driving circuit for a ferroelectric liquid crystal display panel.

[0002]

2. Description of the Related Art Conventionally, as an external circuit for driving a liquid crystal display element, a semiconductor chip is mounted on a film carrier by the TAB method, and individually separated drive circuits are extended around a glass substrate of the liquid crystal display element. There are those connected to the electrode terminals, or those in which the semiconductor chip is directly face-down connected to the electrode terminals extending around the glass substrate of the liquid crystal display element.

[0003]

A liquid crystal display device using a ferroelectric liquid crystal has a smaller gap between glass substrates enclosing the liquid crystal than a conventional liquid crystal display device using an STN type liquid crystal, and generally a driving voltage is also high. Since it is large, the load capacitance seen from the driving circuit is large, and the current value output from the driving semiconductor device is also large. Therefore, the power consumption is larger and the temperature rise of the semiconductor device is also large.

A liquid crystal display element using a ferroelectric liquid crystal has a faster response speed and has a memory property than a liquid crystal display element using another liquid crystal, and thus a large screen can be obtained.
As the load capacitance increases, it is necessary to reduce the wiring resistance of the liquid crystal display element in order to suppress the delay of the liquid crystal drive applied voltage (in order to speed up the rise of the applied voltage to the capacitive load). Therefore, the power consumption of the semiconductor device is further increased and the temperature rise is further increased.

The large temperature rise of the semiconductor device shortens the life of the semiconductor chip used and lowers the reliability.

Further, the temperature of the screen portion of the liquid crystal display element becomes non-uniform over the entire screen due to the heat effect from the semiconductor device, and the optical response characteristic of the ferroelectric liquid crystal has temperature dependence, which deteriorates the display quality. There was a problem.

In view of the above problems of the prior art, the object of the present invention is to suppress the temperature rise of the semiconductor device in the external circuit structure in which the driving semiconductor device is connected to the ferroelectric liquid crystal display element. The purpose is to extend the life of the semiconductor chip and improve the reliability, and to reduce the thermal influence on the liquid crystal display element due to the heat generation of the semiconductor device, thereby realizing high-quality screen display.

[0008]

In order to achieve the above object, the present invention connects a driving semiconductor device to electrode terminals extending around a transparent substrate of a liquid crystal display element using a ferroelectric liquid crystal. In this external circuit structure, a heat dissipation member is attached to the semiconductor device.

In the present invention, preferably, the heat dissipation member is attached so as to be positioned substantially below the upper surface of the liquid crystal display element on the display surface side. As the semiconductor device used in the present invention, a semiconductor device mounted on a film carrier having conductor leads formed thereon, a semiconductor chip faced down on a transparent substrate, or the like is preferably used.

[0010]

In the present invention, the temperature rise of the semiconductor device can be suppressed by the driving external circuit structure in which the heat dissipation material is attached to the semiconductor device, and the thermal influence from the semiconductor device to the liquid crystal display element can be reduced.

Further, by mounting the heat dissipation member so as to be located substantially below the upper surface of the liquid crystal display element on the display surface side, it is possible to prevent the heat dissipation member from projecting to the display surface side and increase the thickness of the entire liquid crystal display device. The semiconductor device can be radiated without heat.

[0012]

Embodiments of the present invention will be described below with reference to the drawings, but the present invention is not limited thereto.

Embodiment 1 FIG. 1A shows a main sectional view of a first embodiment of the present invention. In the figure, 1 is a lower glass substrate, 2 is a glass upper substrate, 3 is a film carrier, 4 is a semiconductor chip, 5 is a printed circuit board, 6 is a heat dissipation member, and 8 and 9 are polarizing plates.

In this embodiment, the TAB method is used in which the semiconductor chip 4 is mounted on the film carrier 3 having the conductor leads on the electrode terminals extending around the lower glass substrate 1 of the liquid crystal display element and then individually separated. The liquid crystal driving semiconductor device is connected in section A using an anisotropic conductive adhesive film, and the printed circuit board 5 for supplying an input signal for operating the semiconductor chip and the film carrier 3 are connected in section B by soldering. The heat dissipation member 6 is attached to the semiconductor chip portion. Here, the heat dissipation member 6 is attached so as to be located below the upper surface C of the display surface, and heat dissipation can be performed without increasing the thickness of the liquid crystal display panel.

Embodiment 2 FIG. 1B shows a main sectional view of a second embodiment of the present invention.

In this embodiment, the semiconductor chip 4 is connected face down to the electrode terminals extending around the lower glass substrate 1 of the liquid crystal display element, and the heat dissipation member is attached to the semiconductor chip portion. Also in this embodiment, the heat dissipation member 6'is attached so as to be positioned substantially below the upper surface C of the display surface, and heat dissipation can be performed without increasing the thickness of the liquid crystal display panel.

In order to attach the heat dissipation member as shown in FIGS. 1A and 1B to the semiconductor element part, mica, mylar,
A method of adhering a heat dissipation member made of aluminum, copper, iron or the like using a heat transfer compound such as silicon grease through an insulation sheet such as silicon rubber, or a method of pressing the heat dissipation member through an insulation sheet is used. .

Embodiment 3 FIG. 1 (c) is a third embodiment of the present invention, in which the semiconductor chip 4 is connected face down to the electrode terminals extending around the lower glass substrate 1 of the liquid crystal display element. Then, a cross-sectional view of a state in which the heat dissipation member 6 ″ is attached to the semiconductor chip part and further the heat dissipation member 6 ″ is brought into close contact with the frame body part 7 surrounding the liquid crystal panel is shown.

[0019]

As described above, according to the external circuit structure for driving a liquid crystal display element of the present invention, the heat dissipation of the semiconductor device is improved and the temperature rise is suppressed, so that the life of the semiconductor chip is extended and the reliability is improved. It is possible to improve the property. Also,
By reducing the heat influence on the liquid crystal display element due to the heat generation of the semiconductor device, a liquid crystal display element with a larger screen can be realized.

[Brief description of drawings]

FIG. 1 is a main cross-sectional view of Examples 1 to 3 of the present invention.

[Explanation of symbols]

 1 Lower Glass Substrate 2 Upper Glass Substrate 3 Film Carrier 4 Semiconductor Chip 5 Printed Circuit Board 6 Heat Dissipating Member 7 Frame Body 8, 9 Polarizing Plate

Claims (4)

[Claims] 1. An external circuit structure in which a driving semiconductor device is connected to electrode terminals extending around a transparent substrate of a liquid crystal display element using a ferroelectric liquid crystal, the semiconductor device comprising:
An external circuit structure for driving a liquid crystal display device, characterized in that a heat dissipation member is attached. 2. The external circuit structure for driving a liquid crystal display element according to claim 1, wherein the main heat radiation portion of the heat radiation member is attached so as to be located substantially below the upper surface of the liquid crystal display element on the display surface side. 3. The external circuit structure for driving a liquid crystal display element according to claim 1, wherein the semiconductor device has a semiconductor chip mounted on a film carrier having conductor leads formed thereon. 4. The external circuit structure for driving a liquid crystal display element according to claim 1, wherein the semiconductor device is formed by facing down a semiconductor chip on a transparent substrate.