JP2000020241A - Touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a malfunction of a touch panel provided with a polarizing plate caused by a temperature change and to facilitate the assembly of that touch panel by providing the polarizing plate placed on the outer surface of a transparent movable substrate without being bonded onto that outer surface by a transparent adhesive agent. SOLUTION: On the upper surface of a transparent movable substrate 3, a polarizing plate 7A is positioned and placed without being bonded by any adhesive member. Namely, concerning such a touch panel 11A, even when there is a difference in the coefficient of thermal expansion between the transparent movable substrate 3 and the polarizing plate 7A, these components can be mutually independently and individually thermally expanded or thermally shrunk. Therefore, the transparent movable substrate 3 is not warped by the temperature change. Further, concerning this touch panel 11A, since the polarizing plate 7A is not bonded with the adhesive member, the polarizing plate 7A can be easily repositioned. Namely, on the upper surface of the transparent movable substrate 3, the polarizing axis of the polarizing plate 7A can be easily and freely adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a touch panel disposed on a surface of a liquid crystal display, a plasma display, an EL display, a CRT display, and the like, and more particularly, to a polarized light for preventing unwanted light reflection. The present invention relates to improvement of a touch panel having a board.

[0002]

2. Description of the Related Art A transparent touch panel as an input switch integrated with a display device is used by being arranged on a display surface of the display device. There are various types of touch panels currently used, and a resistive touch panel is most widely used.

FIG. 2 is a schematic sectional view showing an example of a basic structure of a resistive touch panel.
Such a touch panel 11 is arranged on a surface of a display device 10 such as a liquid crystal display device. The touch panel 11 includes the fixed substrate 1 generally formed of a thin transparent glass plate. However, the fixed substrate 1 may be formed of a transparent resin plate. Various resins such as an acrylic resin and a polycarbonate resin can be used as the transparent resin plate.

On the upper surface of the transparent fixed substrate 1, a transparent conductive film 2 is formed. The transparent conductive film 2 is formed by depositing a thin film of a metal oxide such as ITO (oxide of indium / tin) or an oxide of tin / antimony, or an extremely thin film of a metal such as gold, silver, palladium, or aluminum by a vacuum evaporation method, It can be obtained by forming using a beam evaporation method, a sputtering method, an ion plating method, or the like.

[0005] The touch panel 11 also includes a flexible movable surface substrate 3 (which can be deflected by pressing with an input pen or a finger) generally formed of a thin transparent resin plate. However, the movable substrate 3 may be formed of a very thin transparent glass plate. On the lower surface of the transparent movable substrate 3, a transparent conductive film 4 is formed. This transparent conductive film 4 is
It can be formed similarly to the upper transparent conductive film 2.

The upper electrode plate including the transparent movable substrate 3 and the transparent conductive film 4 on the lower surface thereof is defined by the spacer 5 with respect to the transparent fixed substrate 1 and the lower electrode plate including the transparent conductive film 2 on the upper surface thereof. The transparent conductive films 2 and 4 are arranged so as to face each other with a predetermined space 6 therebetween.

Further, a polarizing plate 7 is bonded on the upper surface of the transparent movable substrate 3 with a transparent resin adhesive. As such a transparent resin adhesive, an acrylic or urethane-based adhesive can be used. In the specification of the present application, the term “polarizing plate” is used as a concept including not only a linear polarizing plate but also a circular polarizing plate and an elliptically polarizing plate. A circularly polarizing plate or an elliptically polarizing plate can be obtained by combining a linearly polarizing plate and a retardation plate.

In the touch panel 11 configured as described above, when the transparent movable substrate 3 is pressed by the input pen or the finger via the polarizing plate 7, the movable substrate 3 bends, and the upper transparent conductive film 4 is pressed at the pressed point. Contacts the lower transparent conductive film 2. Then, the coordinates of the contact point are detected by measuring the electric resistance, and the input information is read.

[0009]

As shown in FIG. 2, in a touch panel 11 in which a polarizing plate 7 is bonded to an upper surface of a transparent movable substrate 3 with an adhesive, the touch panel 11 may be operated under a high temperature environment or a low temperature environment. Is used, the movable substrate 3 may be warped due to a difference in the coefficient of thermal expansion or thermal contraction between the polarizing plate 7 and the movable substrate 3. as a result,
The transparent movable substrate 3 is input from above the polarizing plate 7 with an input pen or a finger.
However, there is a problem that the transparent conductive film 4 on the lower surface of the movable substrate 3 comes into contact with the transparent conductive film 2 on the upper surface of the transparent fixed substrate 1 even though it is not pressed.

When the display device 10 is, for example, a liquid crystal display device, the display device generally also includes a polarizing plate (not shown) to prevent unwanted light reflection. In that case, light representing information displayed on the display device 10 passes through the polarizing plate of the display device and is visually recognized by a human through the touch panel 11, so that the polarizing plate 7 of the touch panel 11 is emitted from the display device 10. The relationship should not reduce the amount of information light emitted. That is, when the polarizing plate 7 of the touch panel is bonded to the upper surface of the transparent movable substrate 3 with an adhesive, the information light polarized and emitted from the display device 10 is allowed to pass through without being reduced.
There is an assembly problem that the polarization axis of the polarizing plate 7 must be strictly controlled and adjusted.

In view of the above-mentioned problems in the prior art, the present invention relates to a touch panel provided with a polarizing plate for preventing unwanted light reflection, and in a touch panel provided with the polarizing plate for preventing unwanted light reflection, the thermal expansion coefficient between the polarizing plate and the transparent movable substrate. It is an object of the present invention to prevent a touch panel from malfunctioning due to a warp of a movable substrate due to a temperature change caused by a difference, and to make it easy to assemble a touch panel including a polarizing plate.

[0012]

The touch panel according to the present invention includes a polarizing plate mounted on the outer surface of the transparent movable substrate without being bonded to the outer surface with a transparent adhesive. It is characterized by having.

In such a touch panel, the touch panel further includes a transparent fixed substrate facing the transparent movable substrate with a predetermined space therebetween, and a transparent fixed substrate is provided on each of the facing surfaces of the movable substrate and the fixed substrate. A conductive layer may be formed.

At least one of the opposing surfaces of the transparent movable substrate and the polarizing plate has a surface uneven structure, and the surface roughness of the surface uneven structure has an arithmetic average roughness Ra in a range of 0.1 to 10 μm. It is preferred to have. Note that this R
a can be measured according to JIS-B-0601.

[0015] It is further preferable that at least one of the opposing surfaces of the transparent movable substrate and the polarizing plate is hard-coated.

As the polarizing plate, one selected from a linear polarizing plate, a circular polarizing plate and an elliptically polarizing plate can be used.

[0017]

FIG. 1 is a schematic sectional view showing a display device with a touch panel according to an embodiment of the present invention. The display device with a touch panel shown in FIG. 1 is similar to that shown in FIG. 2, and the same or corresponding elements are denoted by the same reference numerals.

However, the touch panel 11 shown in FIG.
2A is different from that shown in FIG. 2 in that the polarizing plate 7A is positioned and mounted on the upper surface of the transparent movable substrate 3 without being bonded with an adhesive. That is, such a touch panel 11
In A, even if there is a difference in the coefficient of thermal expansion between the transparent movable substrate 3 and the polarizing plate 7A, they can be individually thermally expanded or contracted independently of each other. Therefore, the movable substrate 3 does not warp due to a temperature change. As a result, it is possible to prevent the transparent conductive film 4 on the lower surface of the movable substrate 3 and the transparent conductive film 2 on the upper surface of the transparent fixed substrate 2 from contacting each other due to the warpage of the movable substrate 3 due to a temperature change, thereby preventing the touch panel from malfunctioning. be able to.

Also, in the touch panel 11A as shown in FIG. 1, the polarizing plate 7A is not bonded on the upper surface of the transparent movable substrate 3 with an adhesive, so that the polarizing plate 7A can be easily positioned. You can start over. That is, on the upper surface of the transparent movable substrate 3, the polarization axis of the polarizing plate 7A can be easily and freely adjusted. Therefore, the touch panel 11A is
It is easy to finely adjust the polarization axis of the polarizing plate 7A so that the information light emitted through the polarizing plate included in the display device is passed as it is after being coupled on the surface of the display device. As a result, the touch panel 11A as shown in FIG. 1 is easier to assemble than the conventional one.

Incidentally, in the touch panel 11A as shown in FIG.
Since the gap between the substrate and the lower surface 7a of the polarizing plate 7A is not tightly sealed with a transparent resin adhesive as in the related art, a minute gap is locally generated to cause light interference fringes such as Newton rings. There is. The appearance of such interference fringes is not preferable when a person visually recognizes the information displayed on the display device 10 through the touch panel 11A.

When the transparent movable substrate 3 is pressed from above the polarizing plate 7A with an input pen or a finger, the polarizing plate 7
The lower surface 7a of A and the upper surface 3a of the movable substrate 3 may be rubbed against each other to cause minute scratches. The occurrence of such abrasion is not preferable when a person visually recognizes the information displayed on the display device 10 through the touch panel 11A.

In order to reduce the adverse effects caused by the above-mentioned light interference fringes and minute scratches, a fine surface uneven structure is formed on at least one of the lower surface 7a of the polarizing plate 7A and the upper surface 3a of the transparent movable substrate 3. It is preferable to form them. This is because such fine surface irregularities act to eliminate visible optical interference fringes,
This is because it also has the effect of making small scratches inconspicuous.

For this purpose, it is preferable that the surface roughness of the surface uneven structure has an arithmetic average roughness Ra in a range of about 0.1 to 10 μm. The surface uneven structure having such a surface roughness can be formed by, for example, embossing.

Further, in order to positively prevent the occurrence of fine scratches, it is preferable to apply a hard coat treatment to at least one or both of the lower surface 7a of the polarizing plate 7A and the upper surface 3a of the transparent movable substrate 3. . When only one of the lower surface 7a of the polarizing plate 7A and the upper surface 3a of the movable substrate 3 is subjected to the hard coat process, the hard coat process is performed on the lower one of the two.

As such a hard coat treatment, a thin film of a thermosetting polysiloxane, an ultraviolet curing type unsaturated polyester, an unsaturated acrylic resin, an unsaturated polyurethane, a polyamide or the like can be formed on the surface.

[0026]

As described above, according to the present invention, in a touch panel provided with a polarizing plate, the warp of the movable substrate due to a temperature change caused by a difference in the coefficient of thermal expansion between the polarizing plate and the transparent movable substrate. In addition to preventing malfunction of the touch panel due to the above, it is possible to facilitate the assembly of the touch panel including the polarizing plate.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing a basic configuration of a display device with a touch panel according to an example of an embodiment of the present invention.

FIG. 2 is a schematic sectional view showing a basic configuration of a conventional display device with a touch panel.

[Explanation of symbols]

 Reference Signs List 1 transparent fixed substrate 2 lower transparent conductive film 3 transparent movable substrate 3a upper surface of transparent movable substrate 4 upper transparent conductive film 5 spacer 6 space 7, 7A polarizing plate 7a lower surface of polarizing plate 11, 11A touch panel

Claims (5)

[Claims] 1. A touch panel, comprising: a polarizer placed on an outer surface of a transparent movable substrate of the touch panel without being bonded to the outer surface with a transparent adhesive. 2. The image forming apparatus further includes a transparent fixed substrate disposed so as to face the transparent movable substrate with a predetermined space therebetween.
The touch panel according to claim 1, wherein a transparent conductive layer is formed on each of the movable substrate and the fixed substrate facing each other. 3. The surface of the transparent movable substrate and the polarizing plate, at least one of which faces each other, has a surface uneven structure, and the surface roughness of the surface uneven structure is an arithmetic average within a range of 0.1 to 10 μm. The touch panel according to claim 1, wherein the touch panel has a roughness Ra. 4. The touch panel according to claim 1, wherein at least one of the mutually opposing surfaces of the transparent movable substrate and the polarizing plate is hard-coated. 5. The touch panel according to claim 1, wherein the polarizing plate is one selected from a linear polarizing plate, a circular polarizing plate, and an elliptically polarizing plate.