JP2013088449A - Liquid crystal display device - Google Patents

Abstract

In a liquid crystal display device, EMI from a TCON substrate is reduced.
A TCON substrate 60 is disposed on the back surface of a lower frame 30 of a liquid crystal display device. A flexible wiring substrate 50 connected to the liquid crystal display panel is connected to the TCON substrate 60. A ground electrode 62 is formed on the right end of the substrate of the TCON substrate 60, and the ground electrode 62 is connected to the lower frame 30 by a conductive tape 70. In the TCON substrate 60, a Tammy terminal 63 is formed. The dummy terminal 63 is connected to the ground wiring of the TCON substrate 60, and the dummy terminal 63 is electrically connected to the lower frame 30 formed of metal by the conductive tape 70. Connecting. Therefore, the entire TCON substrate 60 can be reliably dropped to the ground potential. As a result, EMI can be reduced.
[Selection] Figure 3

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device that takes measures against EMI.

  In a liquid crystal display device, there are a TFT substrate in which pixel electrodes and thin film transistors (TFTs) are formed in a matrix, and a counter substrate in which color filters are formed at locations corresponding to the pixel electrodes of the TFT substrate, facing the TFT substrate. The liquid crystal is sandwiched between the TFT substrate and the counter substrate. An image is formed by controlling the light transmittance of the liquid crystal molecules for each pixel.

  Since liquid crystal display devices are flat and lightweight, they can be used in various fields, such as large display devices such as TVs, medium display devices such as monitors, and small display devices such as mobile phones and DSCs (Digital Still Cameras). ing. Particularly recently, the demand for liquid crystal display devices used in liquid crystal modules for tablets has also increased.

  When the liquid crystal display device is small and thin, warping of the printed wiring board (PCB) becomes a problem. In many cases, the PCB is provided with a terminal row connected to the flexible wiring board at the end. The terminals connected to the flexible wiring board are not arranged over the entire PCB end, but are arranged in part. If there are a portion where terminals exist and a portion where terminals do not exist at the end portion of the PCB, the stress of the PCB becomes non-uniform, which causes warpage of the PCB. When the PCB is warped, it adversely affects the thinning of the liquid crystal display device.

  “Patent Document 1” describes a configuration in which a PCB is prevented from warping by forming dummy terminals on a portion that is not connected to the flexible wiring board in addition to a portion that is connected to the flexible wiring board. .

  On the other hand, when a display device becomes smaller and more precise, radiation of electromagnetic waves from circuit components becomes a problem, which is known as Electro Magnetic Interference (EMI). “Patent Document 2” describes a configuration in which an earth terminal is formed on a flexible wiring board to strengthen the earth to prevent EMI.

  “Patent Document 3” describes a configuration that reduces EMI by disconnecting a component or terminal that easily generates electromagnetic waves from a component or terminal that easily emits electromagnetic waves.

JP 2005-241852 A JP 2006-350243 A JP 11-284291 A

  In recent years, the demand for a tablet-type liquid crystal display device whose display area has a diagonal of about 23 cm has been increasing. In order to make the entire tablet-type liquid crystal display device thin, a liquid crystal display panel mounted with a driver or the like is sandwiched between a metal upper frame and a metal lower frame, and a circuit board is formed from the gap formed at the end of the lower frame. Are arranged on the back surface of the lower frame.

  FIG. 10 is a rear view of the tablet-type liquid crystal display device 1. In FIG. 10, a notch 32 is formed at the end of the lower frame 30 along the side, and the flexible wiring board 50 connected to the liquid crystal display panel passes through the notch 32, and this flexible wiring board 50. Is connected to a wiring board disposed on the back side. Since this wiring board includes a timing controller (TCON), it is referred to as a TCON board 60. The TCON substrate 60 includes various circuit components and wirings. However, in FIG. 10, only TCON is shown as a circuit component in a simplified manner, and wirings are omitted. The TCON board 60 is a wiring board having, for example, about six layers in order to arrange many circuit components and wirings in order to provide various functions.

  In this way, circuit components, wirings, and the like are densely packed on the TCON substrate 60, and a high-frequency signal such as a clock pulse passes. Therefore, emission of electromagnetic waves from these circuits is large, and EMI becomes a problem. As one method for reducing EMI, a method of sufficiently grounding the substrate can be considered.

  In FIG. 10, a ground terminal 62 for grounding the TCON substrate 60 is formed at the end of the TCON substrate 60. The ground terminal 62 is electrically connected to the metal lower frame 30 by the conductive tape 70 and is grounded. Although the ground terminals 62 are formed on the left and right sides of the TCON substrate 60, only the right ground terminal 62 is connected to the lower frame 30 by the conductive tape 70 in FIG. 10.

  As shown in FIG. 11, the conductive tape 70 has a configuration in which a metal foil 71 is coated with an adhesive material 72 in which conductive fine particles 73 are dispersed. As the metal foil 71, copper or Al is used. In general, an acrylic resin is used for the adhesive material 72, and fine particles such as copper, Ni, and carbon are used as the conductive fine particles 73.

  Returning to FIG. 10, the TCON substrate 60 is grounded by the conductive tape 70 only at the right ground terminal 62. Therefore, the central portion or the left end portion of the TCON substrate 60 is not sufficiently grounded. For this reason, the central portion of the TCON substrate 60 and the left end of the TCON substrate 60 are susceptible to EMI. If there is a place where the conductive tape 70 is disposed at the left end portion of the TCON substrate 60, sufficient grounding can be provided at the left end of the TCON substrate 60. However, it is the same that the EMI cannot be sufficiently counteracted at the center portion of the TCON substrate 60. is there.

  On the other hand, as shown in FIG. 10, a flexible wiring board 50 is used to connect with a driver or the like disposed on the liquid crystal display panel. However, when the frequency of the pulse wave increases, the flexible wiring board 50 and the TCON board are used. Signal reflection occurs at the connection portion of the 60 wirings. This signal reflection causes EMI.

  A monitor using a liquid crystal display device (hereinafter referred to as a liquid crystal monitor) is provided with a drain substrate connected to a drain driver or the like in the liquid crystal display panel. As with the TCON substrate in the liquid crystal display device for tablets described above, generation of EMI in the drain substrate becomes a problem when the definition of the screen of the liquid crystal monitor increases.

  An object of the present invention is to sufficiently ground the entire TCON substrate and prevent generation of EMI from the TCON substrate. Another object of the present invention is to prevent the generation of EMI from the end of the connection between the wiring of the TCON substrate and the flexible wiring substrate. Still another object of the present invention is to prevent the generation of EMI in the drain substrate of a liquid crystal display device used in a liquid crystal monitor or the like.

  The present invention solves the above-described problems, and main means are as follows. That is, a backlight is disposed on the back of a liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a pixel electrode and a counter electrode are formed and a counter substrate on which a color filter is formed, and the liquid crystal display panel and the back The light is accommodated by an upper frame and a lower frame, a notch is formed in the lower frame, a flexible wiring board is connected to a terminal portion of the liquid crystal display panel, and the flexible wiring board is connected to the cutting of the lower frame. A liquid crystal display device connected to a TCON substrate disposed on the back surface of the lower frame through a notch, wherein a dummy terminal is disposed at a location other than a portion where the flexible wiring substrate is connected to the TCON substrate, The dummy terminal is covered with a conductive member, and is electrically connected to the lower frame. A display device.

  The other main means is the liquid crystal display device according to (1), wherein the conductive member covers a connection end of the flexible wiring board inside the TCON substrate.

  Still another main means is that a backlight is disposed on the back of a liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a pixel electrode and a counter electrode are formed and a counter substrate on which a color filter is formed. The liquid crystal display panel and the backlight are accommodated by an upper frame and a lower frame, a notch is formed in the lower frame, a flexible wiring board is connected to a terminal portion of the liquid crystal display panel, and the flexible wiring board is Connected to the drain substrate disposed on the side surface of the backlight, a dummy terminal is formed on the drain substrate at a place other than the connection to the flexible wiring substrate, and the dummy terminal is formed by a conductive connecting gasket. A liquid crystal display device connected to the upper frame.

  According to the present invention, sufficient grounding can be established over the entire TCON substrate, and the generation of EMI can be prevented. Further, according to another embodiment of the present invention, it is possible to prevent the generation of EMI at the connection portion between the TCON substrate and the flexible wiring substrate. Accordingly, it is possible to prevent malfunctions caused by EMI in a liquid crystal display device for tablets.

  Furthermore, according to the present invention, in the monitor liquid crystal display device using the drain substrate, it is possible to prevent the generation of EMI from the drain substrate, so that the malfunction caused by the EMI in the monitor using the liquid crystal display device. Can be prevented.

It is a front view of the liquid crystal display device for tablets. It is AA sectional drawing of FIG. 1 is a rear view of a liquid crystal display device for a tablet showing Example 1. FIG. 6 is a rear view of a liquid crystal display device for tablets showing Example 2. FIG. It is a reverse view of the liquid crystal display device for tablets which shows other examples of Example 2. It is a front view of the liquid crystal display device for monitors. It is BB sectional drawing of FIG. It is a figure which shows the example of the external appearance of the gasket for connection. It is a perspective view which shows Example 3 in a drain substrate. It is a back view in the prior art example of the liquid crystal display device for tablets. It is sectional drawing of a conductive tape.

  The contents of the present invention will be described in detail below using examples.

  FIG. 1 is a plan view of a liquid crystal display device 1 for tablets in which the present invention is used. The tablet liquid crystal display device 1 has a configuration in which a liquid crystal display panel is sandwiched between an upper frame 20 and a lower frame 30. The upper frame 20 and the lower frame 30 are fixed by the fixing means 15. The fixing means 15 may be caulked, screwed, or other methods.

  In FIG. 1, the frame area that is the periphery of the display area 10 of the tablet liquid crystal display device 1 is narrow on the upper side and the left side, and wide on the right side and the lower side. For example, a scanning line driver is arranged on the right side, and a drain driver and wiring connected to the TCON substrate 60 are arranged on the lower side, so that the width is widened.

  2 is a cross-sectional view taken along the line AA in FIG. In FIG. 2, a liquid crystal display panel is formed by the TFT substrate 100 and the counter substrate 200. In FIG. 2, the lower polarizing plate and the upper polarizing plate are omitted. A backlight 40 is disposed on the back surface of the liquid crystal display panel. The liquid crystal display panel and the backlight 40 are accommodated by the upper frame 20 and the lower frame 30. The upper frame 20 and the lower frame 30 are fixed by the fixing means 15.

  In FIG. 2, a flexible wiring substrate 50 is connected to the terminal portion 150 of the TFT substrate 100, and the flexible wiring substrate 50 extends to the back surface of the lower frame 30 and is connected to the TCON substrate 60. The flexible wiring substrate 50 connected to the TFT substrate 100 is connected to a TCON substrate 60 disposed on the back surface of the lower frame 30 through a notch 32 formed in the lower frame 30.

  FIG. 3 is a rear view of the liquid crystal display device 1 for tablets in the present embodiment. In FIG. 3, a notch 32 is formed at the end of the lower frame, and a flexible wiring substrate 50 connected to the terminal portion 150 of the liquid crystal display panel is inserted through this portion. Holes 31 are formed in the lower frame 30 in FIG. 3 to reduce the weight of the tablet liquid crystal display device 1 and improve the heat dissipation effect of heat generated inside.

  In FIG. 3, only the TCON 61 is described on the TCON substrate 60, and other circuit components, wirings, and the like are omitted. A ground terminal 62 formed on the right side of the TCON substrate 60 is electrically connected to the metallic lower frame 30 by a conductive tape 70. Conventionally, the entire TCON substrate 60 is grounded only by this.

  In addition to this, the dummy terminal 63 formed between the flexible wiring board 50 and the flexible wiring board 50 is used as the ground terminal 62, and the dummy terminal 63 is connected to the lower frame 30 by the conductive tape 70. By connecting, the entire TCON substrate 60 is sufficiently grounded. The conductive tape 70 is the same as that described with reference to FIGS. In the following description, the conductive tape 70 is representatively described. However, the grounding means is not limited to the conductive tape 70, and a conductive member such as a conductive resin can be used.

  The terminals on the TCON substrate 60 need only be functionally present only at a portion where the terminal is connected to the flexible wiring substrate 50 from the liquid crystal display panel, but a predetermined portion of the TCON substrate 60 such as a portion where the terminal is connected to the flexible wiring substrate. If it is only formed, the substrate is distorted. In order to prevent this, a dummy terminal 63 is provided in addition to the portion connected to the flexible wiring board 50. Conventionally, this dummy terminal 63 is literally a dummy terminal 63 and does not function as a connection.

  In the present invention, this dummy terminal is connected to the ground wiring of the TCON substrate 60, and the dummy terminal 63 is connected to the lower frame 30 by the conductive tape 70, so that the ground at the center portion of the TCON substrate 60 is surely taken. . By ensuring the grounding, the EMI that has conventionally occurred in the central portion of the TCON substrate 60 can be reduced. In this case, the conductive tape 70 can be the same as the conductive tape 70 connected to the ground terminal 62 of the TCON substrate 60.

  By the way, in FIG. 3, if there is a space on the lower substrate on the left side of the TCON substrate 60, the left ground terminal 62 can be grounded using the conductive tape 70. However, even in this case, since the center of the TCON substrate 60 cannot be sufficiently grounded, the advantage of applying the present invention is great.

  FIG. 4 is a back view of the liquid crystal display device 1 for tablets, showing a second embodiment of the present invention. In FIG. 4, a notch 32 is formed at the end of the lower frame 30, and the flexible wiring substrate 50 connected to the terminal portion 150 of the liquid crystal display panel is inserted through this portion, as in FIG. . Also, holes 31 are formed in the lower frame 30 in FIG. 4 to reduce the weight of the liquid crystal display device 1 for tablets and improve the heat dissipation effect from the inside, as in FIG.

  In FIG. 4, a long conductive tape 70 covers the entire end portion of the TCON substrate 60, and is connected to the lower frame 30 on the left and right sides of the TCON substrate 60 for grounding. In FIG. 4, the conductive tape 70 is connected to the ground terminal 62 formed on the TCON substrate 60 on both sides. The feature of FIG. 4 is that not only the conductive tape 70 covers all the dummy terminals 63 but also the portion where the flexible wiring substrate 50 is connected to the wiring formed on the TCON substrate 60. In FIG. 4, wiring on the TCON substrate 60 is omitted.

  The connection portion between the wiring formed on the TCON substrate 60 and the flexible wiring substrate 50 has a discontinuous structure because the material, shape, and the like of the conductor are different. From such a discontinuous structure, reflected waves are likely to be generated particularly in high-frequency signals and the like. Such reflected waves cause EMI and cause malfunctions. In the present embodiment shown in FIG. 4, by covering the connecting portion of the wiring between the flexible wiring board 50 and the TCON board 60 with the conductive tape 70, generation of EMI from the end of the flexible wiring board 50 can be prevented. .

  Also in this embodiment, since the dummy terminal 63 connected to the ground wiring is covered with the conductive tape 70, the generation of EMI from the central portion of the TCON substrate 60 can be prevented. Therefore, in the present embodiment, the effect of preventing EMI by sufficiently grounding the TCON substrate 60 and the effect of preventing the generation of EMI from the boundary between the flexible wiring substrate 50 and the wiring of the TCON substrate 60 are obtained at the same time. And erroneous operation due to EMI can be effectively prevented.

  FIG. 5 shows another example of this embodiment. In FIG. 5, the conductive tape 70 covers all the dummy terminals 63 and the end of the flexible wiring board 50 connected to the wiring of the TCON board. The conductive tape 70 is wider than that of FIG. It extends to the end of the frame 30. Therefore, the ground of the TCON substrate 60 can be more reliably taken even in the central portion. FIG. 5 shows an example in which the left ground terminal 62 of the TCON board 60 is not directly connected to the lower frame 30. However, if space permits, the conductive tape 70 is connected to the lower frame via the left ground terminal 62. 30 can be connected.

  4 and 5, all the dummy terminals 63 are covered with the conductive tape 70, but it is also effective to cover only a part of the dummy terminals 63. Moreover, it is effective not only by covering all the connection parts of the flexible wiring board 50 and wiring, but also by covering a part thereof.

  In this embodiment, the present invention is applied to the liquid crystal display device 2 for monitoring. FIG. 6 is a front view of the monitor liquid crystal display device 2. In FIG. 6, the liquid crystal display panel is accommodated in the upper frame 20, and the outer side of the display area 10 is the upper frame 20.

  7 is a cross-sectional view taken along line BB in FIG. In FIG. 7, a backlight 40 is formed below the liquid crystal display panel formed by the TFT substrate 100 and the counter substrate 200. The liquid crystal display panel and the backlight 40 are accommodated in the upper frame 20 and the lower frame 30. The lower frame 30 is fitted to the upper frame 20 and is fixed by caulking or the like (not shown).

  The monitor liquid crystal display device 2 uses a direct type backlight as the backlight 40 in order to increase the brightness, and the thickness of the backlight 40 is larger than the backlight of the tablet liquid crystal display device 1 or the like. . Therefore, a so-called drain substrate 80 to which the flexible wiring substrate 50 connected to the terminal portion 150 of the liquid crystal display panel is connected is disposed on the side surface of the backlight 40. The drain substrate 80 is called the drain substrate 80 because it is disposed on the drain driver side.

  A flexible wiring substrate 50 is connected to the drain substrate 80 disposed on the side surface of the backlight 40, and the end portion of the lower frame 30 is inserted to connect to the TCON substrate 60 disposed on the back surface of the lower frame 30. In FIG. 7, a TCON 61 is disposed on the TCON substrate 60, and other circuit components are omitted.

  As the monitor liquid crystal display device 2 becomes higher in definition, the clock pulse becomes higher in frequency and causes the problem of EMI as in the case of the liquid crystal display device 1 for tablets. In addition, in order to prevent the substrate from being distorted, the dummy substrate 63 is also formed on the drain substrate 80 other than the portion to which the flexible wiring substrate 50 is connected.

  In FIG. 7, a conductive connecting gasket 90 is disposed at the dummy terminal 63. The conductive connecting gasket 90 is made of an elastic plastic and a conductive filler. In FIG. 7, electrical connection is established by pressing a conductive connecting gasket sandwiched between the side surface of the upper frame 20 and the drain substrate 80. FIG. 8 is an external view of the connection gasket 90. In FIG. 8, the connecting gasket 90 has a rectangular parallelepiped shape, for example.

  FIG. 9 is a perspective view showing a part of the drain substrate 80, and is a perspective view showing a state in which the connecting gasket 90 is arranged on the dummy terminal 63 formed between the flexible wiring substrate 50 and the flexible wiring substrate 50. is there. In FIG. 9, since the connecting gasket 90 disposed on the dummy terminal 63 can be reliably connected to the upper frame 20 by pressing the upper surface with the upper frame 20, the drain substrate 80 is reliably grounded. And the generation of EMI in the drain substrate 80 can be prevented.

  Returning to FIG. 7, the flexible wiring substrate 50 connecting the drain substrate 80 and the TCON substrate 60 is inserted through the notch 32 at the end of the lower frame 30. The problem of EMI in the TCON substrate 60 arranged in the lower frame 30 in FIG. 7 has the same problem as that described in the liquid crystal display device 1 for tablets. Therefore, in order to steadily ground the entire TCON substrate 60, the ground configuration as described in the first and second embodiments can be adopted.

  As described above, according to the present embodiment, in the monitor liquid crystal display device 2, the EMI in the drain substrate 80 and the TCON substrate 60 can be reduced, and therefore the monitor liquid crystal display device 2 with few malfunctions is manufactured. I can do it.

  DESCRIPTION OF SYMBOLS 1 ... Liquid crystal display device for tablets, 2 ... Liquid crystal display device for monitors, 10 ... Display area, 15 ... Fixing means, 20 ... Upper frame, 30 ... Lower frame, 31 ... Hole, 32 ... Notch, 40 ... Back light, DESCRIPTION OF SYMBOLS 50 ... Flexible wiring board, 60 ... TCON board, 61 ... TCON, 62 ... Ground terminal, 63 ... Dummy terminal, 70 ... Conductive tape, 71 ... Metal foil, 72 ... Acrylic adhesive, 73 ... Conductive fine particle, 80 ... Drain Substrate, 90 ... Gasket for connection, 100 ... TFT substrate, 150 ... Terminal part, 200 ... Counter substrate

Claims (10)

A backlight is disposed on the back of a liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a pixel electrode and a counter electrode are formed and a counter substrate on which a color filter is formed,
The liquid crystal display panel and the backlight are accommodated by an upper frame and a lower frame,
A cutout is formed in the lower frame,
A flexible wiring board is connected to a terminal portion of the liquid crystal display panel, and the flexible wiring board is connected to a TCON substrate disposed on the back surface of the lower frame through the notch of the lower frame. There,
Dummy terminals are disposed on the TCON substrate at locations other than the portion to which the flexible wiring substrate is connected,
The liquid crystal display device, wherein the dummy terminal is covered with a conductive member and is electrically connected to the lower frame.   The liquid crystal display device according to claim 1, wherein the conductive member covers a connection end portion of the flexible wiring board inside the TCON substrate.   The liquid crystal display device according to claim 1, wherein the conductive member covers all the dummy terminals.   The liquid crystal display device according to claim 2, wherein the conductive member covers all connection end portions of the flexible wiring board inside the TCON substrate.   The liquid crystal display device according to claim 1, wherein the conductive member is a conductive tape. A backlight is disposed on the back of a liquid crystal display panel in which a liquid crystal layer is sandwiched between a TFT substrate on which a pixel electrode and a counter electrode are formed and a counter substrate on which a color filter is formed,
The liquid crystal display panel and the backlight are accommodated by an upper frame and a lower frame,
A cutout is formed in the lower frame,
A flexible wiring substrate is connected to the terminal portion of the liquid crystal display panel, and the flexible wiring substrate is connected to a drain substrate disposed on a side surface of the backlight,
In the drain substrate, a dummy terminal is formed at a place other than that connected to the flexible wiring substrate,
The liquid crystal display device, wherein the dummy terminal is connected to the upper frame by a conductive connecting gasket.   The liquid crystal display device according to claim 6, wherein the connection gasket covers all of the dummy terminals. The liquid crystal display device further includes a TCON substrate on the back surface of the lower frame, and the substrate is connected to the drain substrate by another flexible wiring substrate,
Dummy terminals are disposed on the TCON substrate at locations other than the portion to which the flexible wiring substrate is connected,
The liquid crystal display device according to claim 6, wherein the dummy terminal is covered with a conductive member and is electrically connected to the lower frame.   The liquid crystal display device according to claim 8, wherein the conductive member covers a connection end portion of the flexible wiring board inside the TCON substrate.   The liquid crystal display device according to claim 6, wherein the conductive member is a conductive tape.

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