JP2001091926A - Liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a problem of blurred characters or pictures on the display due to the pressing force in the input operation, which are difficult to read. SOLUTION: A touch switch 15 consists of an upper transparent substrate 12 with a transparent electrode formed on its surface and a lower transparent substrate 13, with the surface of the transparent substrates disposed facing each other through a spacer 14. A film 16 subjected to anti-reflection treatment is formed on the lower face of the lower transparent substrate 13, and the AR film 16 and an upper polarizing plate 9 of a liquid crystal panel 11 are laminated with a double-coated adhesive tape 17 while forming a specified gap of about 0.2 to about 0.4 mm. The adhesive tape 17 is used as a buffer material and is a frame shaped and have a notch part in its part for a FPC. Thus, even when the touch switch deflects a little, it does not touch the liquid crystal panel. The glass is free from cracks or scratches, and the displayed image is easily observed, and the device can be made small in size, thin and lightweight.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having a light-transmitting input device mounted on a display surface side.

[0002]

2. Description of the Related Art In recent years, as a liquid crystal display device used for a lightweight and portable personal digital assistant (PDA) or the like, a liquid crystal display device equipped with a pen input or a fingertip input device in place of a conventional keyboard input has been known. Many are supplied to the market.

In a conventional example, a liquid crystal display device using a cushioning material between a liquid crystal panel and a touch switch, for example,
The technique is disclosed in Japanese Patent Application Laid-Open No. 8-146392. The outline will be described below.

FIG. 6 is a sectional view for explaining a liquid crystal display device according to a conventional example. Reference numeral 20 denotes a liquid crystal panel, in which two glass substrates, an upper glass substrate 21 on which a transparent electrode or an alignment film (not shown) is formed and a lower glass substrate 22 on which an ITO film, an alignment film, CF or an insulating film (not shown) is formed, are sealed. A liquid crystal 24 is sealed between the substrates 21 and 22 by being fixed by a material 23. An upper polarizing plate 25 on the upper surface of the upper glass substrate 21;
A lower polarizing plate 26 is formed on the lower surface of the lower glass substrate 22. Reference numeral 30 denotes a touch switch, which includes an upper transparent substrate 31 and a lower transparent substrate 32 each of which has a transparent electrode (ITO film) (not shown) having conductivity and serving as an electrode of the touch switch 30. IT0 affixed to
The films are arranged to face each other with a spacer 33 interposed therebetween. The liquid crystal panel 20 and the touch switch 30 are connected to the liquid crystal panel 2.
The upper polarizing plate 25 formed on the upper glass substrate 21 has a function of a cushioning material and is integrally fixed to the liquid crystal display device 35. As shown in FIG. 3, the upper and lower transparent substrates 31 and 32 of the touch switch 30 are each formed of a two-layered PET film formed by laminating two PET films.

In the liquid crystal display device having the above-described configuration, a pattern such as a character or a picture is manually input on the touch switch 30 with the input pen, and the input pattern is displayed on the liquid crystal panel 20 below the touch switch 30. Therefore, the operator can input desired characters and pictures while watching the display via the translucent touch switch 30.

FIG. 7 is a sectional view for explaining the operation of the liquid crystal display device according to FIG. As shown in FIG. 7, the operator presses a desired point on the upper transparent substrate 31 of the touch switch 30 with the input pen 34. Then, the lower transparent substrate 32 and the upper transparent substrate 31 approach each other due to the pressure at the time of input, and I (not shown) serving as electrodes formed opposite to both surfaces thereof.
The TO films contact each other. This ITO film is formed on the opposite surfaces of the upper and lower transparent substrates 31 and 32,
The upper and lower ITO at the input point pressed by the input pen 34
When the films contact each other, a change occurs in the current between the upper and lower ITO films. By detecting this current change, the position of the input point is detected.

The position of the input point detected in this way is output to a drive circuit (not shown) and is repeated on the liquid crystal panel 20 for each input point, so that the operator can obtain lines, characters,
Alternatively, when an input pattern such as a picture is input, a desired pattern is displayed as it is on the liquid crystal panel 20 below the touch switch 30. The operator can see the display via the light-transmitting touch switch 30.

Since such a liquid crystal display device is mounted on a PDA or the like, it is required to be small-sized, light-weight, and thin.
Therefore, a film LCD having a thin film as a transparent substrate is used for the liquid crystal panel, and a thin and light material such as a thin plastic or film is used for the touch switch as much as possible.

In a conventional example, a liquid crystal display device integrated with a protective glass on the upper surface of the liquid crystal display device and a tablet via an adhesive layer is disclosed in, for example, JP-A-8-15679.
The publication discloses the technique. The outline will be described below.

FIG. 8 is a sectional view for explaining a liquid crystal display device according to a conventional example. Reference numeral 40 denotes a liquid crystal panel, in which two glass substrates, an upper glass substrate 41 and a lower glass substrate 42 on which transparent electrodes (not shown) are formed, are fixed with a sealing material 43, and a liquid crystal 44 is sealed between the substrates 41 and 42. ing.
An upper polarizing plate 45 is formed on the upper surface of the upper glass substrate 41, and a lower polarizing plate 46 is formed on the lower surface of the lower glass substrate 42. 47
Is a phase difference plate. Reference numeral 50 denotes a light guide, 51 denotes a tablet board, 52 denotes a non-glare-treated surface, 53 denotes a protective glass, and 54 denotes an upper polarizing plate 45 on the upper polarizing plate 45.
(AG or A)
The liquid crystal display device 56 is configured by a film having an R function. 55 is an input pen.

As shown in FIG. 8, the liquid crystal display 56
Is configured such that, by inputting characters, line drawings, and other information from above the non-glare processing surface 52 with the input pen 55, the input information can be detected by the tablet board 51 and input and displayed on the liquid crystal panel 40. . The image formed on the liquid crystal cell can be used as a visible image by illumination from the light guide 50 constituting the backlight.

With the above configuration, the presence of the adhesive layer 54 allows external light to reach the liquid crystal panel 40 without being reflected at the boundary between the protective glass 53 and the liquid crystal panel 40. Further, since the display image light using the backlight as a light source is transmitted outside without being reflected at the boundary between the protective glass 53 and the liquid crystal panel 40, the transmittance is improved, the brightness is improved, and the display image is displayed with contrast. Very easy to see.

[0013]

However, according to the above two conventional liquid crystal display devices, although the objects of lightening and thinning are satisfied, when inputting with an input pen, a touch switch or a protective glass is required. When the non-glare treated surface is crimped or in the impact test (steel ball drop test), the touch switch or the protective glass is bent, and the pressure due to the bending is not transmitted to the liquid crystal panel. Or, the protective glass is broken and the upper polarizing plate is scratched, or the transparent substrate or the protective glass is bent and abuts the liquid crystal panel to distort even the internal liquid crystal layer. As a result, interference fringes occur. In severe cases, there is a problem that the input characters and pictures become almost unreadable.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent the transparent substrate or the like from being damaged by pressure bonding at the time of input and from damaging the surface of the liquid crystal panel, and at the same time to prevent the transparent substrate or the like from flexing. It is an object of the present invention to provide a liquid crystal display device with an input device that does not come into contact with a liquid crystal panel, suppresses bleeding of a display, makes a display image very easy to see, and enables miniaturization, thinning, and weight reduction.

[0015]

In order to achieve the above object, in a liquid crystal display device according to the present invention, two opposing glass substrates provided with a transparent electrode and an alignment film are fixed by a sealing material. In a liquid crystal display device having a liquid crystal panel in which liquid crystal is sealed between substrates and a touch switch formed of a transparent substrate on a display surface side of the liquid crystal panel, the touch switch has an upper transparent surface on which a transparent electrode is formed. A substrate and a lower transparent substrate having a transparent electrode formed on the surface thereof, wherein the surfaces of the two transparent substrates are arranged to face each other via a spacer, and an anti-reflection processing film (AR film) is provided on the lower surface side of the lower transparent substrate
Wherein the anti-reflection processing film (AR film) and the upper polarizing plate of the liquid crystal panel are bonded via a buffer material.

Further, a liquid crystal panel in which two opposing glass substrates provided with a transparent electrode, a polarizing plate and the like are fixed by a sealing material and liquid crystal is sealed between the two substrates, and a display surface side of the liquid crystal panel. Wherein the touch switch has an upper transparent substrate having a transparent electrode formed on the surface thereof and a lower transparent substrate having a transparent electrode formed on the surface thereof. The upper surface of the upper transparent substrate of the touch switch is provided with an upper polarizing plate, and the anti-reflection processing film (AR film) is provided on the lower surface side of the lower transparent substrate. The processing film (AR film) and the upper glass substrate of the liquid crystal panel are bonded via a buffer material.

Further, the cushioning material is a double-sided adhesive tape.

Further, the double-sided adhesive tape is formed in a frame shape, and a cutout portion for disposing an FPC is provided in a part thereof.

The double-sided adhesive tape is formed in a frame shape, a cutout portion for arranging an FPC is provided in a part thereof, and the thickness of the tape layer is approximately 0.2 to 0.4 mm. It is characterized by.

Further, two opposing glass substrates provided with a transparent electrode and an alignment film are fixed with a sealing material, and a liquid crystal is sealed between the two substrates; and a display surface side of the liquid crystal panel. In the liquid crystal display device, a touch switch made of a transparent substrate is provided on the liquid crystal display device, the touch switch and the liquid crystal panel are arranged to face each other with a buffer material interposed therebetween, and the buffer material is formed in a frame shape. A notch for arranging an FPC is provided in the portion. Further, the interference material is a double-sided adhesive tape.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A liquid crystal display device according to the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention, FIG. 3 is a double-sided adhesive tape, FIG. 3 (a) is a plan view, and FIGS.
FIG. 4A is a cross-sectional view taken along line AA, FIG. 4 is a partial cross-sectional view showing a configuration of a double-sided adhesive tape, FIG. 5 shows a state in which a double-sided adhesive tape is attached to a touch panel, and FIG. FIG. 5B is a cross-sectional view taken along the line BB of FIG. First,
In FIG. 1, a liquid crystal panel 11 includes, on an inner surface side of a transparent upper glass substrate 1 and a lower glass substrate 2 arranged opposite to each other, indium tin oxide (ITO) obtained by doping indium oxide with silver oxide. A) a transparent metal film is formed by depositing a powder, and the upper transparent electrode 3 and the lower transparent electrode 4 in which a desired electrode pattern is formed by etching the metal film;
Are formed. Further, an upper alignment film 5 and a lower alignment film 6 are provided thereon, and a liquid crystal material 8 is injected while being sealed with a sealing material 7. Further, an upper polarizing plate 9 and a lower polarizing plate 10 are provided on the upper surface of the upper glass substrate 1 and the lower surface of the lower glass substrate 2, respectively.

The touch switch 15 serves as an electrode of the touch switch 15 and has conductivity (not shown).
The film has an upper transparent substrate 12 and a lower transparent substrate 13 attached to one side thereof, and the upper transparent substrate 12 is placed on the lower transparent substrate 13 such that the ITO films attached to the respective transparent substrates face each other.
Are arranged via a spacer 14 to constitute a resistive touch switch.

As shown in FIGS. 1, 3, 4 and 5,
The configuration of the liquid crystal display device 19 is such that an antireflection processing film (AR film) 16 is provided on the lower surface side of the lower transparent substrate 13 of the touch switch 15, and the antireflection processing film (AR film) 16 is provided.
Double-sided adhesive tape 17 (for example, Dainippon Ink and Chemicals, PET base type double-sided adhesive tape for spacer, part number 86250A)
The liquid crystal panel 11 and the touch switch 15 are attached and integrated by bonding via W).

The structure of the double-sided adhesive tape 17 is shown in FIG.
As shown in (c), the adhesive 17 is applied to the front and back of the support 17a.
b is applied, and a release paper 17c is stuck on the surface. Here, the shape of the double-sided adhesive tape 17 is shown in FIG.
As shown in (a) and (b), a notch 17d for disposing the FPC 20 (see FIG. 5) is provided in a part of the frame, and the thickness of the tape layer is reduced. In the present embodiment, t1 = about 0.31 mm (commercially available) is used. If the thickness t1 of the tape layer is too small, when the touch switch 15 is pressed when inputting with an input pen or the like, the pressure due to the bending of the touch switch 15 propagates to the liquid crystal panel. Conversely, if the thickness is too large, there is no effect due to the pressing, but the device itself becomes thick. Therefore, as an appropriate thickness, t1 = approximately 0.2 to approximately 0.4 m
m is preferred.

The above-mentioned double-sided adhesive tape for a PET base type spacer has an acrylic adhesive and is suitable as a double-sided adhesive tape for a spacer, and has excellent smoothness, heat resistance and repulsion resistance.

As shown in FIG. 5, the adhesive area of the double-sided adhesive tape 17 is attached to the lower surface of the touch switch 15 and substantially four sides of the outer edge of the liquid crystal panel 11 excluding the active area (for arranging the FPC 20). By attaching the liquid crystal panel 11 to the touch switch 15 by attaching the liquid crystal panel 11 to the touch switch 15 and the liquid crystal panel 11 (excluding the notch 17d), a predetermined gap (approximately 0.2 to approximately 0.4) is provided.
In addition to the function of a cushioning material described later as a spacer for forming mm), the spacer also serves to prevent intrusion of dust. By sticking the touch switch 15 on almost all four sides except the notch 17d, the touch switch 15 can be stuck on the liquid crystal panel 11 in a stable and parallel state. The thickness of the touch switch 15, t2 = about 1 mm.

In the liquid crystal display device 19 having the above-described configuration, by inputting a pattern such as a character or a picture on the touch switch 15 by handwriting with an input pen or a fingertip, a display responding to the input content is displayed below the touch switch 15. LCD panel 1
1, the operator can input desired characters and pictures through the translucent touch switch 15 while watching the display.

As described in the prior art for the operation of the liquid crystal display device, the operator operates the touch switch 1 with the input pen.
5. A desired point of the upper transparent substrate 12 is adhered. Then, the lower transparent substrate 13 and the upper transparent substrate 12 approach each other due to the pressure at the time of input, and the ITO films (not shown), which are electrodes formed opposite to each other and serve as electrodes, come into contact with each other. This ITO film is formed on the entire surface of the upper and lower transparent substrates 12 and 13,
When the upper and lower ITO films contact each other at the input point pressed by the input pen, a change occurs in the current between the upper and lower ITO films. By detecting this current change, the position of the input point is detected.

The position of the input point detected in this way is output to a drive circuit (not shown) and is repeated on the liquid crystal panel 11 for each input point, so that the operator can obtain lines, characters,
Alternatively, when an input pattern such as a picture is input, a desired pattern is displayed in response to the liquid crystal panel 11 below the touch switch 15 as it is. The operator can see the display through the translucent touch switch 15.

In this embodiment, the touch switch 1
By providing an anti-reflection processing film (AR film) 16 on the lower surface side of the lower transparent substrate 13, external light can be transmitted to the lower transparent substrate 13.
And reaches the liquid crystal panel 11 without being reflected at the boundary of the liquid crystal panel 11. Further, the display image light using the backlight as a light source is transmitted outside without being reflected at the boundary between the touch switch 15 and the liquid crystal panel 11 due to the presence of the AR film 16, so that the transmittance is improved and the luminance is improved. And
The contrast makes the displayed image very easy to see. Further, even if the touch switch 15 is slightly flexed as a whole due to the pressing force at the time of input, the pressing force is relieved, and at the same time, even when the transparent substrate of the touch switch 15 is cracked, the function of preventing scattering is achieved. Do not scratch the surface.

Further, the anti-reflection treatment film (AR film)
16 and the upper polarizer 9 of the liquid crystal panel 11 are fixed to each other via the above-mentioned cushioning material (double-sided adhesive tape) 17 to integrate them, so that the double-sided adhesive tape 17 serves as a spacer and the AR film 16 and the upper polarizer 9, a predetermined gap is formed between the touch switch 15 and the touch switch 15 by the pressing force at the time of input.
When the touch panel 15 is slightly bent as a whole, the gap absorbs the bending and the touch switch 15 does not contact the liquid crystal panel 11, so that the liquid crystal panel 11 is not damaged.

Therefore, the flexure of the touch switch due to the pressing force at the time of input is buffered by the AR film 16 and especially the double-sided adhesive tape 17, and propagates to the liquid crystal layer in the liquid crystal panel 11 disposed thereunder. Can be suppressed. As in the related art, it is possible to suppress the blurring of the display on the liquid crystal display unit caused by the distortion of the liquid crystal in the vicinity of the input point and the inability to determine the pattern of the input characters and pictures.

FIG. 2 is a sectional view of a liquid crystal display according to a second embodiment of the present invention. In FIG. 2, a liquid crystal display device 19A has an upper polarizer 9 of a liquid crystal panel 11 formed on an upper surface of an upper transparent substrate 12 of a touch switch 15, and other configurations are the same as those of the above-described first embodiment. Therefore, the description is omitted. Since the polarizing plate 9 comes to the outermost surface, reflection below the polarizing plate 9 can be suppressed.

Therefore, similarly to the first embodiment, the bending of the touch switch 15 due to the pressing force at the time of input is buffered by the AR film 16 and especially the double-sided adhesive tape 17, and the liquid crystal panel disposed therebelow. 11 can be prevented from propagating to the liquid crystal layer. As in the related art, it is possible to suppress the blurring of the display on the liquid crystal display unit caused by the distortion of the liquid crystal in the vicinity of the input point and the inability to determine the pattern of the input characters and pictures. By the polarizing plate 9 and the AR film 16 on the outermost surface, light reflection between the lower surface of the polarizing plate 9 and the liquid crystal panel 11 is eliminated, and a liquid crystal display device 19A with improved surface quality is obtained.

[0035]

As described above, according to the liquid crystal display device of the present invention, by applying a double-sided adhesive tape as a spacer between the liquid crystal panel and the touch switch, the touch switch can be pressed by the pressure at the time of input. Even if it is bent, it does not come into contact with the liquid crystal panel, and propagation to the liquid crystal layer can be suppressed as much as possible. Conventionally, the liquid crystal is distorted near the input point.
This makes it possible to prevent a pattern such as an input character or a picture from being indistinguishable. Further, by using the AR sheet together with the double-sided adhesive tape described above, the image display becomes very easy to see, and at the same time, the pressure-bonding force is reduced, and the effect of damage to the liquid crystal element is eliminated, and the buffer effect is doubled. Even if the glass is broken, scattering is prevented and the surface of the liquid crystal panel is prevented from being damaged.

Further, by adhering the double-sided adhesive tape to approximately four sides of the liquid crystal panel except for the active surface, intrusion of dust can be prevented, and at the same time, the touch switch can be disposed on the liquid crystal panel in parallel by excreting the FPC into the notch. Can be bonded in a stable state.

[Brief description of the drawings]

FIG. 1 is a sectional view illustrating a liquid crystal display device according to a first embodiment of the present invention.

FIG. 2 is a sectional view illustrating a liquid crystal display device according to a second embodiment of the present invention.

FIG. 3 is an explanatory diagram of a double-sided adhesive tape used in FIGS. 1 and 2;

FIG. 4 is a partial cross-sectional view showing a configuration of the double-sided adhesive tape of FIG.

FIG. 5 is an explanatory view showing a state in which the double-sided adhesive tape in FIGS. 1 and 2 is attached to the back surface of the touch panel.

FIG. 6 is a cross-sectional view illustrating a liquid crystal display device according to a conventional example.

FIG. 7 is a cross-sectional view illustrating the operation of the liquid crystal display device of FIG.

FIG. 8 is a cross-sectional view illustrating a liquid crystal display device according to another conventional example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Upper glass substrate 2 Lower glass substrate 3 Upper transparent electrode 4 Lower transparent electrode 8 Liquid crystal material 9 Upper polarizing plate 10 Lower polarizing plate 11 Liquid crystal panel 12 Upper transparent substrate 13 Lower transparent substrate 14 Spacer 15 Touch switch 16 Anti-reflection processing film (AR 17) Double-sided adhesive tape (buffer material) 17d Notch 19, 19A Liquid crystal display device t1 Thickness of tape layer of double-sided adhesive tape t2 Thickness of touch switch

Claims (7)

[Claims] 1. A liquid crystal panel in which two opposing glass substrates provided with a transparent electrode, an alignment film and the like are fixed by a sealing material, and a liquid crystal is sealed between the two substrates; and a display surface side of the liquid crystal panel. Wherein the touch switch has an upper transparent substrate having a transparent electrode formed on the surface thereof and a lower transparent substrate having a transparent electrode formed on the surface thereof. An anti-reflection processing film (AR film) is provided on the lower surface side of the lower transparent substrate, and the anti-reflection processing film (AR film) and the upper polarizing plate of the liquid crystal panel are buffered. A liquid crystal display device characterized by being bonded via a material. 2. A liquid crystal panel in which two opposing glass substrates provided with a transparent electrode, a polarizing plate and the like are fixed by a sealing material, and a liquid crystal is sealed between the two substrates; and a display surface side of the liquid crystal panel. Wherein the touch switch has an upper transparent substrate having a transparent electrode formed on the surface thereof and a lower transparent substrate having a transparent electrode formed on the surface thereof. The upper surface of the upper transparent substrate of the touch switch is provided with an upper polarizing plate, and the anti-reflection processing film (AR film) is provided on the lower surface side of the lower transparent substrate. A liquid crystal display device wherein a processing film (AR film) and an upper glass substrate of a liquid crystal panel are bonded via a buffer material. 3. The liquid crystal display device according to claim 1, wherein the cushioning material is a double-sided adhesive tape. 4. The liquid crystal display device according to claim 3, wherein the double-sided adhesive tape is formed in a frame shape, and a cutout portion for arranging an FPC is provided in a part thereof. 5. The double-sided adhesive tape is formed in a frame shape, a cutout portion for arranging an FPC is provided in a part thereof, and a thickness of the tape layer is approximately 0.2 to 0.4 mm. The liquid crystal display device according to claim 3, wherein: 6. A liquid crystal panel in which two opposing glass substrates provided with a transparent electrode, an alignment film and the like are fixed by a sealing material, and a liquid crystal is sealed between the two substrates; and a display surface side of the liquid crystal panel. In the liquid crystal display device, a touch switch made of a transparent substrate is provided on the liquid crystal display device, the touch switch and the liquid crystal panel are arranged to face each other with a buffer material interposed therebetween, and the buffer material is formed in a frame shape. F in part
A liquid crystal display device comprising a cutout for disposing a PC. 7. The liquid crystal display device according to claim 6, wherein the interference material is a double-sided adhesive tape.