JP2002341372A - Liquid crystal display device and portable terminal equipment - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To prevent electromagnetic waves entering and exiting through a display screen, and to eliminate various adverse effects such as malfunctions of the liquid crystal display device itself or surrounding electronic devices by this electromagnetic wave shield. According to a liquid crystal display device (7), a color liquid crystal display panel (8) and a backlight unit (3) are accommodated in a case (9), and a transparent conductive film (11) is deposited on a transparent substrate (10). It is arranged on the display screen side of the liquid crystal display panel 8. When the transparent conductive film 11 is electrically connected to the case 9 and the case 10 is grounded (grounded), a current is electrically supplied to the ground, thereby electromagnetically shielding the liquid crystal display panel 8.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device in which the effects of electromagnetic waves are reduced or eliminated. In particular, the present invention relates to a liquid crystal display device in which the use of a resistive touch panel made of a synthetic resin material such as a PET-PET type has eliminated the adverse effects of the influence. Further, the present invention relates to a mobile terminal device equipped with the liquid crystal display device of the present invention.

[0002]

2. Description of the Related Art A conventional liquid crystal display will be described with reference to FIG. In this liquid crystal display device 1, an STN type or TFT type color liquid crystal display panel 2 and a backlight unit 3 arranged on the back surface of the panel 2 are accommodated in a case 4.

The liquid crystal display panel 2 has a liquid crystal layer interposed between two transparent glasses, and further has a driving IC provided on a transparent glass substrate or a circuit board.

According to the liquid crystal display device 1 having such a configuration, the electromagnetic waves emitted therefrom adversely affect peripheral devices and the like.

In order to take such measures to suppress the emission of electromagnetic noise (EMI countermeasures), there has been proposed a technique of arranging a transparent conductive film on the inner surface of a transparent glass to shield the electromagnetic waves (see Japanese Patent Application Laid-Open No. H5-4286). ).

[0006]

However, the above technique has the following problems due to the formation of the transparent conductive film for electromagnetic wave shielding inside the liquid crystal display panel 2 depending on the film thickness.

That is, since the transmittance of light largely depends on the cell gap of the liquid crystal layer, the provision of the transparent conductive film affects the cell gap, and the uniform film is formed by various factors in manufacturing. It is difficult to form a thick transparent conductive film, and as a result, color unevenness or the like occurs due to a local difference in transmittance.

When the liquid crystal display panel 2 is driven, a voltage change is constantly applied to the electrodes at regular intervals. However, when a transparent conductive film for electromagnetic wave shielding is formed inside the liquid crystal display panel 2, However, it is not sufficient to shield the electromagnetic wave noise generated from the inside of the liquid crystal display panel 2 at that time, and the electromagnetic wave noise caused by the voltage change is emitted to the display screen side.

In recent electronic devices for portable terminals, the liquid crystal display device 1 shown in FIG.
As shown in the figure, even if a transparent conductive film for shielding electromagnetic waves is not formed inside the liquid crystal display panel 2, a touch panel 5 is further mounted on the display screen, thereby eliminating a keyboard and operation buttons, thereby improving portability. A liquid crystal display device 6 is presented.

In such a liquid crystal display device 6 of the touch panel type, instead of the transparent conductive film for shielding electromagnetic waves, electromagnetic waves can be shielded similarly with the surrounding electronic devices by the touch panel 5. In addition, the touch panel 5 itself is affected by the electromagnetic waves, which easily causes a malfunction.

However, the problem of this point can also be avoided by setting the timing of the data capture of the touch panel 5 to avoid such a malfunction.

Therefore, in the touch panel type liquid crystal display device 6, it can be said that the electromagnetic wave shield on the display screen side has not been raised at all.

However, in recent years, when the touch panel type liquid crystal display device 6 is used for a portable terminal device,
The range of use is extremely wide, and depending on the surrounding electronic devices, the emission of strong electromagnetic waves may damage the liquid crystal display device 6. Conversely, electromagnetic waves leaking from the liquid crystal display device 6 may be present near electronic devices that are sensitive to the electronic devices, causing damage to the devices such as malfunction.

In recent years, a resistive touch panel has been used as the touch panel 5. In this type, in order to further enhance portability, a mainstream glass substrate-glass substrate bonding type is used as a substrate material. Recently, those using synthetic resins such as PET-PET type have been proposed.

Since the PET-PET type resistive touch panel uses a PET material as a substrate material, it is possible to obtain weight reduction and flexibility.

However, when such a PET-PET type resistive touch panel is arranged on the liquid crystal display surface side, it responds to the vibration of electromagnetic wave noise emitted from the display surface (resonance).
There is also a problem of emitting sound.

As described above, even in the liquid crystal display device shown in FIG. 4 and the liquid crystal display device in which portability is emphasized as shown in FIG. 5, the electromagnetic waves emitted from the display surface cannot be sufficiently shielded. As a result, electromagnetic waves emitted from the liquid crystal display device cause malfunctions in surrounding electronic devices.

Also, electromagnetic waves emitted from surrounding electronic devices may enter the display surface of the liquid crystal display device, causing malfunction of the device.

In addition, in the field of use where sharp images are required, such as color liquid crystal display devices, and especially in small terminals such as portable terminal equipment, even if the above-mentioned problem of the discharge shield is improved, Needless to say, the image quality must not be reduced.

Accordingly, the present invention has been completed in view of the above description, and its purpose is to enhance display quality, prevent electromagnetic waves from entering and exiting through a display screen, and use this electromagnetic wave shield to improve the liquid crystal display device itself. Another object of the present invention is to provide a high quality and highly reliable liquid crystal display device by eliminating various adverse effects such as malfunctions of surrounding electronic devices.

It is another object of the present invention to provide a liquid crystal display device which not only prevents electromagnetic waves from entering and exiting through a display screen but also prevents electromagnetic waves from entering and exiting the entire device, and is resistant to electromagnetic interference. .

Still another object of the present invention is to provide a PET-PET
In a liquid crystal display device in which a resistive touch panel made of a synthetic resin material such as a type is arranged on the liquid crystal display surface side, the noise generated by the reaction (resonance) to the vibration of the electromagnetic noise emitted from the display surface has been reduced or eliminated. It is to provide a high quality liquid crystal display device.

It is another object of the present invention to provide a portable terminal device which has all the effects of the liquid crystal display device of the present invention mounted thereon.

[0024]

In the liquid crystal display device of the present invention, a transparent conductive film is deposited on the display screen side of the liquid crystal display panel, and ground means is provided to electrically supply the transparent conductive film to the ground. And the liquid crystal display panel is electromagnetically shielded.

In another liquid crystal display device according to the present invention, the grounding means is a housing of a liquid crystal display panel.

Still another liquid crystal display device according to the present invention is characterized in that a touch panel is provided on an outer surface of the transparent conductive film.

In the liquid crystal display device according to the present invention, the touch panel is a resistive touch panel made of a synthetic resin material.

Further, a portable terminal device according to the present invention is characterized by mounting the liquid crystal display device according to the present invention.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION A liquid crystal display device of the present invention (Example 1)
(Example 3) will be described with reference to the drawings.

(Example 1) FIG. 1 is a schematic sectional view of a liquid crystal display device 7 of the present invention, and FIG. 6 shows a main structure of a liquid crystal display panel 8 of the liquid crystal display device 7.

According to the liquid crystal display device 7 shown in FIG.
An N-type color liquid crystal display panel 8 and a backlight unit 3 disposed on the back of the panel 8 are made of a metal case 9.
Within. In this example, the color liquid crystal display panel 8 is described as an STN type, but may be a TFT type.

A transparent conductive film is provided on the display screen side of the liquid crystal display panel 8. This deposition may be provided directly, but as shown in FIG. 1, a transparent conductive film 11 is deposited on a transparent substrate 10 such as glass or an acrylic plate, and the transparent substrate 1
0 may be provided on the display screen side of the liquid crystal display panel 8.

The transparent conductive film 11 is electrically connected to the case 9 and the metal case 10 is grounded, thereby electrically supplying a ground to the case 9. 8 is electromagnetically shielded. In this embodiment, the grounding case 9 forms the grounding means.

FIGS. 9 to 12 show a structure in which the transparent conductive film 11 is electrically connected to the case 9 as described above.

FIG. 9 shows contact conduction, FIG. 10 shows adhesive conduction, FIG.
1 is a TAB system, and FIG. 12 is a metal wire system electrically connected to the ground except for the case.

Thus, according to the liquid crystal display device 7 of the present invention, since the liquid crystal display panel 8 is electromagnetically shielded, the display quality is improved, and the electromagnetic waves entering and exiting through the display screen are prevented. Various adverse effects such as malfunctions of the device itself or surrounding electronic devices have been eliminated. Moreover, in the present invention,
Electromagnetic waves that enter and exit through the entire device are prevented, and the liquid crystal display device 7 is resistant to electromagnetic interference.

(Preferred Example) In the case of using a transparent substrate 10 on which a transparent conductive film 11 is adhered, the following configuration is preferable.

An acrylic resin plate is preferably used for the transparent substrate 10 in that light weight and high transmittance can be obtained. The transparent conductive film 11 formed on the substrate 10 has a sheet resistance,
Optimum conditions are determined according to the film thickness and transmittance.

When an ITO film is formed as the transparent conductive film 11 by sputtering, vapor deposition, or coating, the film has a resistivity ρ (Ω · cm), a sheet resistance R (Ω / □), and a film thickness d. There is the following relationship with (Å).

Assuming that ρ = R · d × 10 ⁻³ resistivity ρ is 2.0 × 10 ⁻³ Ω · cm, 100
Ω / □, 30Ω / □ at 670Å, and 10Ω / □ at 2000Å. The transmittance depends on the wavelength depending on the film thickness d, and has a minimum value and a maximum value as shown in FIG. When a high transmittance of 85% or more is obtained at a light wavelength of 550 nm, the sheet resistance R is in the range of 70 to 500Ω and 12 to 25Ω.

Next, a configuration example of the liquid crystal display panel 8 will be described. FIG. 6 is an enlarged sectional view of a main part of the liquid crystal display panel 8.

The liquid crystal display panel 8 may be a complete transmission type, a reflection type, or a transflective type liquid crystal display device.
Is used, it becomes a transmission type or a semi-transmission type. if,
When the backlight unit 3 is not used, it is a reflection type.

According to the liquid crystal display panel 8 shown in FIG. 6, a transparent substrate 12 made of glass or synthetic resin and a transparent substrate 13 are disposed to face each other. On the outer surface of the transparent substrate 12, a phase difference plate made of polycarbonate or the like is provided. 14 and iodine polarizing plate 1
5 are sequentially stacked, and a retardation plate 16 made of polycarbonate or the like and an iodine-based polarizing plate 17 are sequentially stacked on the outer surface of the transparent substrate 13. These are attached using an adhesive made of an acrylic material.

In the figure, a backlight unit 3 is further provided on a polarizing plate 17. Backlight 3
Is a light source 19 such as a cold cathode tube or an LED on the end face of the light guide plate 18.
Are arranged, light emitted from the light source 19 is introduced into the light guide plate 18, and light is emitted from the light guide plate 18 to the liquid crystal display panel 8.

In the liquid crystal display panel 8, on the transparent substrate 12, a signal electrode 20 and an alignment film (not shown) made of a polyimide resin rubbed in a certain direction are sequentially formed. Note that S is placed between the signal electrode 20 and the alignment film.
An insulating layer made of iO ₂ or the like may be interposed.

A reflective film or semi-transmissive film 21 is formed on the inner surface of a transparent substrate 13 such as a glass substrate.
1, a color filter 22 is provided. Further, a black matrix which is a light-shielding film formed of a thin film made of a metal such as aluminum or chromium or a photosensitive resist may be formed between the color filters 22.

Then, on the color filter 22, SiO
₂ and an overcoat layer 23 made of a resin, a scanning electrode 24 and an alignment film (not shown) made of a polyimide resin rubbed in a certain direction on the overcoat layer 23.
Are sequentially formed. This scanning electrode 24 is orthogonal to the signal electrode 20. Note that an insulating layer made of SiO ₂ or the like may be provided between the scanning electrode 24 and the alignment film.

When the film 21 is formed of a reflective film, the liquid crystal display device 7 becomes a reflection type liquid crystal display device.

According to the transflective liquid crystal display device 7,
The semi-transmissive film 21 has both light transmissive and light reflective properties, and prevents a phase difference from occurring when sandwiched between two polarizing plates.

The reflection film or semi-transmissive film 21 may be specular or scattering. In order to manufacture the film 21 having a scattering property, an irregular shape is formed by a resin, and a reflective film or a semi-transmissive film may be formed thereon.

The color filter 22 is of a pigment dispersion type,
That is, a photosensitive resist prepared in advance with a pigment (red, green, blue, or the like) is applied on a substrate and formed by photolithography.

Each of the transparent substrates 12 and 13 thus formed is
Are bonded together with a sealing material 26 via a liquid crystal layer 25 made of a chiral nematic liquid crystal twisted at an angle of, for example, 200 to 270 °. Furthermore, both transparent substrates 1
A large number of spacers 36 are arranged between 2 and 13 to keep the thickness of the liquid crystal layer 25 constant.

In the liquid crystal display device 7 having the semi-transmissive film 21 as described above, when used as a reflection type (reflection mode), irradiation light by external illumination such as sunlight or a fluorescent lamp is used. Passes through the polarizing plate 15, the phase difference plate 14, and the liquid crystal panel sequentially, but the light incident inside the liquid crystal panel passes through the color filter 22 and reaches the semi-transmissive film 21,
Then, the light is reflected by the semi-transmissive film 21, passes through the liquid crystal panel, passes through the phase difference plate 14 and the polarizing plate 15, and is emitted.

On the other hand, when the liquid crystal display device 7 is in the transmission mode, the irradiation light of the backlight unit 3 is
7, a retardation plate 16, and a transparent substrate 13 of a liquid crystal panel.
, Sequentially pass through the semi-transmissive film 21, pass through the color filter 22, pass through the liquid crystal panel, pass through the retardation plate 14 and the polarizing plate 15, and are emitted.

Further, by forming the semi-transmissive film 21 on the transparent substrate 13, in the reflection mode, particularly by increasing the reflectance, a brighter display is obtained, and in the transmission mode, a high contrast is obtained. The reflection mode and the transmission mode can be enhanced to the extent that both functions of the reflection mode and the transmission mode can be satisfied.The panel used in the reflection mode can be used in the transmission mode under the same conditions. In each case, stable and vivid color display was achieved.

The reflective film or semi-transmissive film 21 is made of, for example, a metal thin film such as aluminum, chromium, SUS, or Ag. As the film thickness increases, the light transmittance decreases and the light reflectivity increases.

(Example 2) FIG. 2 is a sectional view of another liquid crystal display device 7a according to the present invention, and the same reference numerals are given to the same parts as those shown in FIG.

In the liquid crystal display device 7 shown in (Example 1), when a transparent conductive film is applied on the display screen side of the liquid crystal display panel 8, a transparent substrate 10 such as glass or an acrylic plate is used. The transparent conductive film 11 is adhered to the polarizing plate 15 provided on the display screen side of the liquid crystal display panel 8 instead of such a configuration. The conductive film 11 is applied.

FIG. 1 shows a configuration through such other members.
It is shown in FIG. In this example, a transparent film provided with an ITO conductive transparent film may be used.

The transparent conductive film 11 is electrically conducted to the case 9 and the metal case 9 is grounded (grounded), thereby electrically supplying the ground.
Thus, the liquid crystal display panel 8 is electromagnetically shielded.

(Example 3) FIG. 3 is a sectional view of another liquid crystal display device 7b according to the present invention, and the same reference numerals are given to the same parts as those shown in FIG.

In this example, the liquid crystal display device 7 or 7a of (Example 1) or (Example 2) is a liquid crystal display device 7b in which a touch panel 27 is further disposed on the outer surface of the transparent conductive film 11.

In the liquid crystal display device 7b, a resistive touch panel 27 (for example, a PET-PET type) in which a touch panel is made of a synthetic resin material is provided on the liquid crystal display device 7a.
Is arranged. Other configurations are the same as those of the liquid crystal display device 7a.

The liquid crystal display device having such a configuration and PET-PET
In the resistive touch panel of the type, it was confirmed that the touch panel operated normally and did not emit an abnormal sound.

To explain this point in detail, the phenomenon that the PET-PET type resistive touch panel taps the surface of the liquid crystal display and generates sound due to the influence of electromagnetic wave noise generated by the driving method using the STN liquid crystal. However, this phenomenon could be suppressed.

The liquid crystal used in the STN liquid crystal belongs to a dielectric substance according to its electrical classification. When a direct current is continuously applied to the liquid crystal, the liquid crystal is polarized, and does not function as an optical switching function. In order to avoid this, it is necessary to drive the liquid crystal artificially with an AC voltage, and to achieve this, it is necessary to invert the voltage applied to the opposing ITO electrode at regular intervals. Actually, a voltage of 20 to 30 V is applied to the liquid crystal, and a voltage of more than 20 V is applied to one electrode,
A voltage of several volts is applied to the other electrode. After a certain period of time, the voltage applied to the electrodes is increased from 20 V to several V,
The voltage is inverted from several volts to twenty volts. At this time, a sudden change in the voltage causes electromagnetic noise, which is emitted from the liquid crystal display surface. In a liquid crystal display device with a conventional structure, electromagnetic wave noise emitted from the display surface is placed on the liquid crystal display surface without being shielded.
By vibrating a PET-PET type resistive touch panel and tapping between the touch panel and the liquid crystal display surface to generate a vibration sound, an electromagnetic wave shield with a conductive film on the display surface was formed. , Electromagnetic noise is reduced,
It was confirmed that the noise was eliminated.

(Mobile Phone of the Present Invention) A mobile phone 28 equipped with the liquid crystal display devices 7, 7a and 7b will be described with reference to FIG.

According to the portable telephone 28, the small casing 2
The liquid crystal display devices 7, 7a, 7b are arranged in the interior of the device. An antenna 30 for transmission / reception is provided on the upper part of the housing 29,
Further, a receiver 31 and a microphone 32 are formed on the surface.

(Portable Terminal of the Present Invention) A portable terminal 33 provided with the liquid crystal display devices 7, 7a and 7b will be described with reference to FIG.
The mobile terminal 33 is shown as various information terminals other than the mobile phone 28. For example, a clock, a calculator, a game machine, a pedometer (registered trademark), a GPS, a POS, a handy terminal, an industrial instrument, and the like are not limited thereto.

Also in this portable terminal 33, the liquid crystal display devices 7, 7a, 7b are arranged in a small casing 34.

It should be noted that the present invention is not limited to the above embodiment, and various changes and improvements can be made without departing from the scope of the present invention. For example, in the above-described embodiment, the description has been made with the STN type simple matrix type color liquid crystal display device. However, in addition, a bistable type simple matrix type color and monochrome liquid crystal display device, and a monochrome type STN type simple matrix device are described. The same operation and effect can be obtained even in the liquid crystal display device of the above or the TN type simple matrix type liquid crystal display device.

Although the portable terminal is exemplified as the device provided with the liquid crystal display device of the present invention, the present invention is also applicable to various devices using the liquid crystal display device as a display device. For example, it may be used as a display board of various display devices such as a sewing machine, a stereo, a musical instrument, a video, an ATM, a copier and a facsimile, a station, a restaurant, and a display panel in a factory.

[0073]

As described above, according to the liquid crystal display device of the present invention, a transparent conductive film is deposited on the display screen side of the liquid crystal display panel, and the ground means is provided to electrically supply the transparent conductive film to the ground. The LCD panel is electromagnetically shielded to enhance display quality and prevent electromagnetic waves from entering and exiting the display screen.This electromagnetic wave shield causes malfunctions of the liquid crystal display device itself or surrounding electronic devices. Various adverse effects such as have been eliminated. In addition, an electromagnetic wave that enters and exits through the entire device is prevented, and a liquid crystal display device that is resistant to electromagnetic interference is obtained.

According to the present invention, in a liquid crystal display device having a touch panel disposed on an outer surface of the transparent conductive film,
Responds to vibration of electromagnetic noise emitted from the display surface (resonance)
The sound generated due to the noise can be reduced or eliminated.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a liquid crystal display device of the present invention.

FIG. 2 is a schematic sectional view of another liquid crystal display device of the present invention.

FIG. 3 is a schematic sectional view of still another liquid crystal display device of the present invention.

FIG. 4 is a schematic sectional view of a conventional liquid crystal display device.

FIG. 5 is a schematic sectional view of another conventional liquid crystal display device.

FIG. 6 is an enlarged sectional view of a main part of a liquid crystal display panel 8 of the liquid crystal display device of the present invention.

FIG. 7 is a front view of the mobile phone according to the present invention.

FIG. 8 is a front view of the portable terminal according to the present invention.

FIG. 9 is an explanatory diagram of a configuration for electrically connecting a transparent conductive film to a case (housing).

FIG. 10 is an explanatory diagram of a configuration for electrically connecting a transparent conductive film to a case (casing).

FIG. 11 is an explanatory diagram of a configuration for electrically connecting a transparent conductive film to a case (casing).

FIG. 12 is an explanatory diagram of a configuration for electrically connecting a transparent conductive film to a case (casing).

FIG. 13 shows the thickness and transmittance of a transparent conductive film (wavelength of light: 550 n).
FIG. 6 is a diagram showing a relationship with m).

FIG. 14 is a schematic sectional view showing a configuration in which a transparent conductive film is applied on a polarizing plate.

[Explanation of symbols]

 1, 6, 7, 7a, 7b: liquid crystal display device 2, 8, liquid crystal display panel 3: backlight unit 4, 9, case 5, 27: touch panel 10, transparent Substrate 11, 12, 13 ... transparent conductive film

Continued on the front page F-term (reference) 2H088 EA22 HA02 HA05 HA08 HA28 JA05 JA13 MA20 2H089 HA18 HA40 JA08 JA10 QA10 RA05 RA10 TA02 TA09 TA18 UA09 2H092 GA62 GA64 NA17 PA06 PA13 QA07 QA10 RA10 5G435 AA04 AA18 BB12 BB12 CB12 GG33 HH12 HH14

Claims (5)

[Claims] 1. A transparent conductive film is deposited on the display screen side of a liquid crystal display panel, and ground means is provided to electrically supply the transparent conductive film to a ground, thereby electromagnetically shielding the liquid crystal display panel. A liquid crystal display device characterized by the above-mentioned. 2. The liquid crystal display device according to claim 1, wherein said grounding means is a housing of a liquid crystal display panel. 3. The liquid crystal display device according to claim 1, wherein a touch panel is provided on an outer surface of said transparent conductive film. 4. The liquid crystal display device according to claim 3, wherein said touch panel is a resistive touch panel made of a synthetic resin material. 5. A portable terminal device equipped with the liquid crystal display device according to claim 4.