JP2003066483A - Image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image display device in which GND (ground) potential is stabilized. SOLUTION: This image display device has a driving circuit impressing a video signal to image display elements in the display device and the driving circuit has a printed circuit board PCB supplying GND potential to the driving circuit and a metallic-bottom frame becoming the structural body of the image display device and the GND potential is supplied to the GND electric power supplying part of the PCB from the bottom frame by a metallic conductive member having spring functions at many points.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an image display device.

[0002]

2. Description of the Related Art As a method of supplying a driving voltage, a driving signal and the like from the outside to a liquid crystal display device, a driving driver DR is provided on a tape carrier package TCP and the driving voltage and the signal are supplied to the TCP from a printed circuit board PCB. , TC
A so-called TCP method for supplying a video signal or a scanning signal from P to a liquid crystal display device is widely used. Further, a COG method in which the driving DR is directly mounted on the substrate and a driving circuit built-in method in which the driving DR is directly formed on the substrate are known.

Further, as a backlight for allowing light as a light source to enter the liquid crystal display element, a so-called direct type backlight in which the light source is formed under the liquid crystal display element and a so-called side in which the light source is formed on a side surface of the liquid crystal display element are provided. Light type backlights are known.

For the purpose of holding the backlight,
A so-called lower frame formed on the lower side of the backlight,
There is known an upper frame which is formed on the upper side of a liquid crystal display element and hides the peripheral portion of the liquid crystal display device from an observer.

[0005]

In order to stabilize the signal potential supplied to the liquid crystal display element, it is desirable to stabilize the potential supplied to the driving driver DR that forms the signal potential. PCB that supplies electric potential to the TCP
It is desirable to stabilize the potential of. At this time, PCB
Since the potential is normally supplied from one end of the liquid crystal display device, potential fluctuation may occur due to the wiring resistance of the PCB on the input side and the output side. The potential transmitted on the PCB by the wiring pattern includes DC potential, various digital signals, G
There are ND and so on. Of these, the DC potential is the power supply potential and does not affect the output from the driving driver DR as long as it is within the fluctuation allowable range of the driving driver DR. Also a clock,
Digital signals such as data are binary or 1 as High / Low level as the potential on the wiring pattern.
If the value is less than 0 and is within the range of the reference value of the voltage, there is no influence on the output from the driving driver DR. However, since the GND potential causes the drive driver DR to operate with the potential as a reference potential, the potential fluctuation may affect the output voltage from the drive driver DR, that is, the signal potential supplied to the liquid crystal display element. is there. G
When the ND potential is supplied from only one end of the PCB, it is formed along the edge of the liquid crystal display device, so that the GND potential is inevitably formed in a long and narrow shape on the PCB. Therefore, due to capacitive coupling with various digital signals added to other wiring patterns and the like, the potential changes due to capacitive coupling.
There is a problem that the ND potential fluctuates, and as a result, the signal potential supplied from the driving driver DR to the liquid crystal display element fluctuates at one end and the other end of the screen, and a brightness gradient, brightness unevenness, etc. occur within the screen.

Further, since the frequency of the video signal is higher than that of the scanning signal, the rate of leakage to the outside as EMI is high, and the EMI
There is a problem that the level is high.

Therefore, an object of the present invention is to provide a liquid crystal display device in which the GND potential supplied to the driving driver DR of the liquid crystal display device is stabilized, thereby stabilizing the image quality and improving the EMI.

Further objects of the present invention will become apparent herein.

[0009]

A typical means for solving the above problems will be briefly described as follows.

In an image display device having an image display element, the image display element displaying an image using a video signal input from a drive circuit, and having a substrate supplying a GND potential to the drive circuit. A conductive lower frame is provided on the non-observer side of the image display element of the device, and the lower frame and the substrate for supplying the GND potential are electrically connected at multiple points by a conductive connecting member.

As another means, a backlight unit is further provided between the image display element and the lower frame,
A light source is disposed on at least one end of the backlight,
At least a part of the lower frame is disposed on both the lower side and the upper side of the light source, and the conductive connection is disposed between the lower frame formed on the upper side of the light source and the substrate that supplies the GND potential. Provide a member.

As another means, a member having a spring property is used as the conductive connecting member.

As another means, an upper frame disposed on the viewer side of the substrate for supplying the GND potential is further provided, and a dent portion is provided on the upper frame, and the substrate for supplying the GND potential is provided by the dent portion. The pressure is applied to the conductive connecting member.

As another means, a controller board for supplying a voltage and a signal is further provided on the board for supplying the GND potential, and the lower frame and the GND of the controller board are provided.
And, the lower frame and the GND of the substrate for supplying the GND potential are electrically connected to each other.

As another means, the controller board and the board for supplying the GND potential are integrally formed.

As another means, an insulating sheet is further provided between the light source and the lower frame. Further means and effects of the present invention will become apparent in the present specification including the claims.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 18 shows an explanatory view of one constitution of an image display device using a liquid crystal display element. The drain substrate DP is connected to the video signal line (not shown) of the TFT substrate.
A voltage and a signal are applied to TCP from CB, and a video signal formed by the driving driver DR on TCP is applied. The G-PCB is a gate substrate, but it can be omitted by forming wiring on the TFT substrate. The gate potential controls ON / OFF of the TFT, and the precision of voltage control is not required as compared with the video signal. Therefore, even if the output voltage is affected by the GND potential fluctuation, the influence on the image quality is small. is there. vice versa,
Regarding the video signal, the stabilization of the GND potential affects the image quality more than the gate potential, and the stabilization is extremely important.

Further, since the video signal is a signal with a high number of bits due to multicolor display, the transmission frequency of the video signal signal becomes higher than the transmission frequency of the gate signal signal. For this reason, so-called EMI, which affects the outside as high-frequency noise, occurs from the substrate that transmits the video signal. To suppress this, it is effective to stabilize the GND potential adjacent to the transmission path of the video signal.

FIG. 1 shows the drain substrate PCB of the image display device.
The schematic cross-sectional structure in the vicinity is shown. An example using a liquid crystal display element will be described, but the invention is not limited to this. The upper frame UF is omitted from the figure. A liquid crystal display element is formed by having a TFT substrate on which an active element is formed and a CF substrate facing the TFT substrate. A CFL that serves as a light source is provided on the lower side surface of the liquid crystal display element, and the light from the CFL is supplied to the light guide plate LG by the reflector RF. The light in LG is
It is reflected by the reflection sheet RS provided on the lower side of LG and applied to the liquid crystal display element.

Various voltages, signals, and GND potentials from the drain substrate PCB are electrically supplied to the TCP, and the TCP
Is converted into a video signal by the video signal driving driver DR provided in the, and applied from the output terminal of the TCP to the input terminal of the TFT substrate to supply the video signal to the liquid crystal display element. Supply of various signals and voltages to the PCB is a substrate TC provided with a TFT controller TCON (not shown)
Therefore, the connector CN2 provided on the TC and the connector CN1 provided on the PCB are electrically connected by the flexible substrate FPC. In Figure 1, PCB and F
Although the PC is separately configured, if the PCB is flexible, a part of the extending portion may be directly connected to the CN2.

The supply of the GND potential of the PCB is a luminance gradient,
It is desirable to supply a stable potential that does not fluctuate in order to eliminate uneven brightness. Therefore, in this embodiment, the lower frame LF is provided below the liquid crystal display element with a conductive material, a carbon-containing resin, a metal-coated resin, or a metal.
By stabilizing the GND potential by electrically connecting the lower frame LF and the GND potential exposed surface of the PCB at multiple points.

The LF is relatively much larger than the PCB and can stabilize the GND potential in terms of the GND area. P
It is desirable to configure the LF with an area 10 times or more that of the GND wiring on the CB. Further, since there is a degree of freedom in selecting the thickness as compared with the PCB, it is desirable to make the thickness of the LF larger than the thickness of the conductive layer of the GND of the PCB. Further, since the LF according to the present embodiment has a low resistance for supplying GND and has a function as a structural member,
It is necessary to have both conductivity and strength, and it is desirable to use metal, for example, SUS.

To stabilize the PCB GND, L
At the same time as the supply of GND by F, the GN of LF to PCB
It is necessary to reduce the power supply resistance to D. Therefore,
In FIG. 1, SP1 was used as the connecting member. FIG. 12 shows one configuration of SP1. It is a metallic member and has a spring function by being partially deformed to form a PC.
Stable connection between B and LF. Further, the image display device can be assembled more easily than the case where the PCB and the LF are directly soldered, and there is an advantage that the disassembly and correction are easy. Of course, a coiled spring shape may be used. As another material, as shown in FIG. 11, a metal foil MT may be wound around the core material CM. In this case, CM
When a cushioning material such as foaming resin or sponge is used, it is possible to have a spring function. Further, in this case, it is necessary that the GND potential of the PCB is exposed at the SP1 contact portion.

In the system in which the CFL is arranged on the side surface as shown in FIG. 1, the LF is not normally formed between the CFL and the PCB. However, in that case, it is structurally difficult to achieve electrical connection by SP1. Therefore, in this embodiment, as shown in FIG. 1, a part of LF is also formed on the CFL, and P is formed at this part.
The GND and LF of CB were electrically connected by SP1.

4 to 6 show examples of the structure of the LF of this portion. FIG. 4 shows an example in which the LF is bent over a wide range. As is clear from FIG. 1, since the CFL or RF is arranged under the bent portion of the LF, its assembly requires more consideration than the conventional case where there is no bent portion. For example, by facilitating the assembly of the LF by forming the bent portion of the LF only on the side where the drain PCB is provided.

FIG. 6 shows an example in which only the portion where SP1 abuts is folded back. This improves the assemblability without affecting the connection resistance between the PCB and LF.

FIG. 5 is an intermediate configuration between FIG. 4 and FIG.
This is an example in which the SP1 contact portion is configured to have a wide width and the non-contact portion is provided with relatively narrow folds. In FIGS. 4 and 5, since the folded portion is also provided in the non-contact portion, the bending rigidity of the LF is improved, and the strength of the LF as a structure can be improved as compared with the conventional structure.
Further, in FIG. 5, it is possible to improve the assemblability and the strength at the same time.

The connector CN1 may be arranged on the upper side of the PCB. In FIG. 1, since the connector CN1 is formed on the lower side of the PCB, the CN1 and the TCP are arranged on the other surface of the PCB. Therefore, the CN1 and the TCP can be arranged independently of each other. It is possible to reduce the frame size of the image display device. Also FPC
The required length is also reduced, which leads to cost reduction.

The GND potential is stabilized by the GND of the drain substrate.
It goes without saying that the potential is not limited to the potential, and the GND potential of the gate substrate may be used. Further, since various voltages and signals are supplied to the drain substrate PCB via the substrate TC, it is important to stabilize the GND potential of the substrate TC. Therefore, in FIG. 1, TC and LF are also electrically connected by SP2. As the SP2, in addition to the member having the spring property as shown in FIG. 12, a metal screw shown as SP2 in FIG. 2, a conductive tape shown as SP2 in FIG. 3, a metal wiring and the like can be used.

By supplying the GND potential of PCB and the GND potential of TC by the same GND potential, that is, the lower frame LF, even if the GND potential fluctuates, the fluctuation similarly occurs in TC and PCB. , It becomes possible to cancel the influence relatively. This effect is
The high-frequency noise is more G than the DC fluctuation of the GND potential itself.
When it jumps into the ND, it works effectively as a reduction of the influence and contributes to stable display. That is, for example, GND supplied from TC via FPC and GND supplied from LF via SP1.
When the LF is separated, the noise that finally appears in the GND of the PCB when the noise is added to the LF is (1)
GND supplied from TC through FPC, and (2) L
There will be two lines of GND supplied from F through SP1. In this case, since the FPC has wiring resistance, high frequency noise on the GND in the route of (1) and (2)
The high-frequency noise on the GND in the path of GND has different timings, waveforms, etc. As a result, the noise superimposed on the GND input to TCP is the combination of (1) and (2), and the noise increases. This is because it will end up. Figure 1
As described above, by supplying the GND potential of PCB and the GND potential of TC by the same GND potential, that is, the lower frame LF, such a problem can be avoided and stable display can be performed. Also, reduction of EMI is realized.

FIG. 7 shows an example of the structure of the upper frame UF near the drain substrate PCB. It is drawing explaining the structure of PCB vicinity in the non-arrangement part of CN1, TC is abbreviate | omitted and described.

A recessed portion DP is formed on the upper frame UF. The recessed portion becomes a protruding portion when viewed from the PCB side. On the other hand, a claw-shaped bent portion is formed on the lower side of the UF, and the UF and LF are fixed by the bending. FIG. 9 shows a schematic drawing of the dent portion DP and the bent portion TS. The UF is made of metal, and the recessed portion DP is formed by pressing. Further, the claw-shaped portion TS is formed on the lower side and is bent to connect the LF and the UF. Of course, the combination of UF and LF is T
Instead of S, screws may be used. D according to the structure of FIG.
Since P pushes the PCB from above, pressure is applied to SP1 to electrically connect GND between the PCB and LF. Further, since SP1 has a spring-like property as shown in FIG. 12, it becomes possible to appropriately hold the pressure from the DP.

FIG. 14 is a schematic plan view showing the arrangement portion of the DP, and it can be provided at any place as long as the area where the DP does not contact the DR.

[Embodiment 2] The difference between this embodiment and Embodiment 1 lies in the difference in the connecting portion between the DP and the PCB. FIG. 8 shows a diagram corresponding to FIG. 7 of the first embodiment. In this embodiment, the DP is provided between the TCP forming parts of the PCB. FIG. 13 is a plan view. There was a TCP connection area on the PCB, and the DP was abutted between the TCP formation areas.

In the present embodiment, since the DP is formed between the TCP forming areas, the DP can be made large and the connection of SP1 can be more stabilized.

[Embodiment 3] The difference between this embodiment and Embodiment 2 lies in the difference in the connection between the DP and the PCB. FIG. 10 shows a view corresponding to FIG. 8 of the second embodiment. In this embodiment, DP and PCB
A cushioning material KS is provided between them. This makes SP1
The pressure of can be stabilized more.

[Fourth Embodiment] FIG. 15 shows a view corresponding to FIG. 8 of the second embodiment. The difference between this embodiment and Embodiment 2 is that RF
This is because the insulating sheet IS is provided between LF and LF.

As a result, the CFL and LF were electrically separated from each other.

As a result, the influence of the high frequency noise of the CFL on the lower frame UL is reduced, and the GND level is stabilized.

[Fifth Embodiment] FIG. 16 shows a view corresponding to FIG. 15 of the fourth embodiment. The difference of this embodiment from the fourth embodiment is that an insulating sheet IS is provided between the upper RF and LF.

As a result, the CFL and LF were electrically separated from each other.

[Sixth Embodiment] FIG. 17 shows a view corresponding to FIG. 16 of the fifth embodiment. The difference between this embodiment and Embodiment 5 is that the insulating sheet IS is configured to cover RF.
As a result, the CFL and LF were electrically separated from each other more reliably.

Further, by using a member in which IS is formed in advance as the RF member, the simplification of the assembly is realized as compared with the case where the IS is separately provided.

IS may be provided on the outside of RS by an insulating tape. Conversely, RS may be formed inside the insulating member IS.

In the fourth and fifth embodiments, LF is CFL in the partially bent structure as shown in FIG. 5 or FIG.
It also has the effect of electrically separating the PCB from the PCB.
D-level stabilization is realized.

[Seventh Embodiment] FIG. 19 shows a view corresponding to FIG. 1 of the first embodiment. In this embodiment, the driving driver DR is set to T
This is an example of a so-called COG method of directly mounting on the FT substrate. Even in this method, the need to suppress the GND potential fluctuation of the PCB is the same as in the TCP method, and the application of the present invention can improve the brightness gradient and the brightness unevenness.

In addition, PCB and FPC are integrated into one F
It may be a PC. Further, the PCB, the FPC, and the FPC connecting the CN1 and the CN2 may be integrated. In this case, the number of parts can be reduced by connecting the FPC directly to CN2.

[Embodiment 8] FIG. 20 shows a view corresponding to FIG. 1 of the first embodiment. In this embodiment, the driving driver DR is set to T
This is an example formed on the FT substrate, and therefore the driving driver DR is not shown. A driver circuit can be formed on the TFT substrate by using a crystalline semiconductor such as polycrystalline silicon or continuous grain boundary silicon. Even in this case, the need for stabilizing the GND potential supplied to the drive circuit is the same, and the application of the present invention can improve the brightness gradient and the brightness unevenness.

In addition, the PCB and FPC are integrated into one F
It may be a PC. Further, the PCB, the FPC, and the FPC connecting the CN1 and the CN2 may be integrated. In this case, the number of parts can be reduced by connecting the FPC directly to CN2.

[Embodiment 9] FIG. 21 is an example of another image display device for stabilizing the GND potential. Pixels are formed under the TFT substrate (not shown). In the pixel, a self-luminous element such as so-called EL, organic EL, OLED is formed. The drive voltage or drive current for these pixels is supplied from a drive circuit formed of, for example, polycrystalline silicon or continuous grain boundary silicon below the TFT substrate.

SM is a shield material, and TFT
The above self-luminous element is protected and isolated from the external environment, and is fixed by a molding material ML. ML is preferably a thermosetting or photocurable resin. When an organic material is used for the self-luminous element, a photo-curable material is used as ML to prevent deterioration of the organic material due to the manufacturing process. TF
It is desirable to fill an inert gas such as helium, nitrogen or argon between the T substrate and ML. Also SM and T
It is desirable to provide a hygroscopic material between the FTs to improve the reliability of the self-luminous element, and further it is desirable to provide an oxygen adsorbing material. As an example, carbon, silica gel, dried plant fiber,
Porous ceramics or the like can be applied. The larger the surface area, the better the adsorption effect. Carbon nanotubes, fullerenes, etc. are also desirable.

The SM of this embodiment is made of metal, and also has the function of stabilizing the GND potential, like the LF of the first embodiment. The PCB is directly connected to this, and the FPC is connected from the PCB.
A voltage, a signal, and a GND potential are supplied to the input terminal of the TFT via the, and converted into a driving voltage or a driving current by a driving circuit on the TFT. Especially in the case of current drive type
Since the current flowing through the circuit also increases, it is even more important to stabilize the GND, and the effect of improving the image quality by the stabilization becomes great. The same applies to EMI improvement.

Also, the connection cable CABLE enables PCB
A TC having a controller for supplying a signal and a voltage is also directly mounted on the SM to improve noise resistance as in the first embodiment.

In this embodiment, the TFT is provided with the input terminal portion on the lower side and is connected to the wiring formed outside the FPC at this portion.
Furthermore, the input terminal of the FPC and the output terminal formed on the TFT side of the PCB were connected. Although details of the wiring are omitted in FIG. 21, they can be easily understood. As a result, a single-layer FPC having a conductive layer only on the outside can be applied to the FPC, so that cost reduction can be realized.

[Embodiment 10] FIG. 22 is a view corresponding to FIG. 21, and is an example in which a PCB and TC are integrated.

Since there is no difference in GND potential between PCB and TC, GND is further stabilized.

Further, FIG. 25 shows an example in which the PCB and the FPC are also integrally formed, and the GND is further stabilized.

[Embodiment 11] FIG. 23 is a view corresponding to FIG. 22, showing an example in which the FPC is not exposed from the TFT substrate. This realizes protection of the bent portion of the FPC.

[Embodiment 12] FIG. 24 is a diagram corresponding to FIG. 22 and shows an example in which SM and FPC are protected by the same ML. This improves reliability. The present invention is not limited to the embodiments of Examples 1 to 12 including the technical idea and effects, and the configurations and effects according to the technical ideas disclosed in the specification including the claims are within the scope of the present invention. It includes everything.

[0061]

A typical example of the effect of the present invention is as follows. That is, it is possible to provide an image display device that stabilizes the GND potential and eliminates the brightness gradient and the brightness unevenness. Also EM
An image display device with reduced I level can be provided.

Further, various effects described with the configuration in the embodiment can be realized.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a schematic sectional view of an essential part of an embodiment of the present invention.

FIG. 3 is a schematic sectional view of an essential part of an embodiment of the present invention.

FIG. 4 is an explanatory diagram of a planar configuration of constituent members according to an embodiment of the present invention.

FIG. 5 is an explanatory diagram of a planar configuration of a component member according to an embodiment of the present invention.

FIG. 6 is an explanatory diagram of a planar configuration of constituent members according to an embodiment of the present invention.

FIG. 7 is a schematic sectional view of an essential part of an embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view of an essential part of another embodiment of the present invention.

FIG. 9 is an explanatory diagram of shapes of constituent members according to an embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view of an essential part of another embodiment of the present invention.

FIG. 11 is an explanatory diagram of shapes of constituent members according to an embodiment of the present invention.

FIG. 12 is an explanatory diagram of shapes of constituent members according to an embodiment of the present invention.

FIG. 13 is an explanatory diagram of another embodiment of the present invention.

FIG. 14 is an explanatory diagram of an example of the present invention.

FIG. 15 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 16 is a schematic sectional view of an essential part of another embodiment of the present invention.

FIG. 17 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 18 is an explanatory diagram of an example of the present invention.

FIG. 19 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 20 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 21 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 22 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 23 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 24 is a schematic sectional view showing an essential part of another embodiment of the present invention.

FIG. 25 is a schematic sectional view showing an essential part of another embodiment of the present invention.

[Explanation of symbols]

TFT ... TFT substrate, TCP ... Tape carrier package, PCB ... Printed circuit board, CN1 ... Connector, CN2
... Connector, DR ... Driving driver, SP1 ... Connection member, SP2 ... Connection member, LG ... Light guide plate, RS ... Reflective sheet, IS ... Insulating sheet, CFL ... Light source, RF ... Reflector,
LF ... lower frame, UF ... upper frame, TC ... controller board, DP ... dented portion, TS ... folded portion, KS ...
Cushion material, CM ... Heart material, MT ... Metal foil, SM ... Shield material, ML ... Mold material.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor, Takayuki Ota             Hitachi Device, 3681 Hayano, Mobara-shi, Chiba             Engineering Co., Ltd. F-term (reference) 2H092 GA64                 2H093 NC02 NE03 NE07                 5G435 AA01 BB12 BB15 EE02 EE41                       GG34

Claims (7)

[Claims] 1. An image display device having an image display element, the image display element displaying an image using a video signal input from a drive circuit, and having a substrate for supplying a GND potential to the drive circuit. The image display device of the image display device has a conductive lower frame on the observer side, and the lower frame and the substrate for supplying the GND potential are electrically connected at multiple points by a conductive connecting member. Characteristic image display device. 2. A backlight unit is provided between the image display element and the lower frame, a light source is disposed at at least one end of the backlight, and at least a part of the lower frame is below the light source. And on both sides,
The image display device according to claim 1, further comprising: the conductive connecting member disposed between a lower frame formed on the upper side of the light source and the substrate that supplies the GND potential. 3. The image display device according to claim 2, wherein the conductive connecting member has a spring property. 4. An upper frame disposed closer to an observer than the substrate for supplying the GND potential, the upper frame having a dent portion, and the dent portion for applying a pressure to the substrate for supplying the GND potential. The image display device according to claim 1, wherein a pressure is applied to the conductive connecting member by applying the pressure. 5. A controller board that supplies a voltage and a signal to the board that supplies the GND potential, wherein the lower frame and the GND of the controller board, and the lower frame and the GND of the board that supplies the GND potential, respectively. The image display device according to claim 1, wherein the image display device is electrically connected. 6. The image display device according to claim 5, wherein the controller substrate and the substrate for supplying the GND potential are integrally formed. 7. The image display device according to claim 2, wherein an insulating sheet is provided between the light source and the lower frame.