JP4445151B2 - Touch panel - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a resistive film type analog touch panel used for a user to input data by directly pressing a display screen of information with a finger or the like in devices such as computers, various terminals, vending machines, and ATMs.
[0002]
[Prior art]
The touch panel is usually placed on top of the liquid crystal display to form an input unit. When the user looks at the liquid crystal display and presses any display location with a finger or a pressing bar, which location is pressed. Is automatically determined as an input signal, and transparency and accuracy in determining the pressed position are required. FIG. 3 shows an example of such a touch panel. FIG. 3A is a plan view, the dimensions are about 70 mm in length and about 80 mm in width, and FIG. 3B is a cross-sectional view taken along line BB in FIG. In the cross-sectional view, the lower surface side is a glass substrate 1, and a plan view thereof is shown in FIG. 4, and the transparent electrode 2 occupies a considerable area on the upper surface and is formed in a rectangular shape. 4 is formed so that the end thereof extends to the terminal electrode portion 12 on the lower side of the glass substrate 1 and serves as a terminal electrode for connection to an external circuit. On the transparent electrode 2, transparent resin spacers 5 are arranged at regular intervals.
[0003]
In FIG. 3B, the upper surface side of the touch panel is a transparent film 6, which is a transparent resin material or the like, but some products use thin glass. The transparent film 6 is tightly stretched and bonded to the glass substrate 1 with an adhesive 13 in a state where the distance from the glass substrate 1 is constant. A plan view of the transparent film 8 is shown in FIG. 5. The transparent electrode 7 is also provided in a rectangular shape on the lower surface, and the connection electrodes 8 and 9 are formed on both upper and lower sides of the electrode. The end portion 8a is guided to the lower side, and the end portion 9a projects from the connection electrode 9 in the middle. As can be seen from the plan view of FIG. 3A, the transparent electrode 7 overlaps the transparent electrode 2 almost entirely.
[0004]
The glass substrate 1 in FIG. 4 has the connection electrodes 10 and 11 provided at the end portions of the connection electrodes 3 and 4 in addition to the terminal electrode portion 12 on the lower side. As shown in FIG. 3A, when the glass substrate 1 and the transparent film 6 are overlapped, the end 8a of the connection electrode 8 of the transparent film 6 overlaps with the connection electrode 10 of the glass substrate 1 and protrudes from the middle of the connection electrode 9 The end 9 a of the electrode overlaps with the connection electrode 11. Therefore, the connection electrodes 8 and 10 and the connection electrodes 9 and 11 are conductively connected by sandwiching the conductive adhesive material between the connection electrodes and joining the glass substrate 1 and the transparent film 6 with the adhesive 13. The end portions of the four connection electrodes 3, 4, 8, 9 in total, two on the glass substrate 1 and two on the transparent film 6, all gather at the terminal electrode portion 12 on the lower side of the glass substrate 1. Although not shown, a flexible circuit board or the like is joined to this portion, and the touch panel is connected to an external control circuit.
[0005]
To further explain each of the above components, first, the glass substrate 1 can be made of various glass plates such as soda glass, quartz glass, borosilicate glass, etc., and has a thickness that does not cause warpage. Is called. Many are about 0.7 to 1.1 mm thick. On the other hand, the transparent film 6 needs to be flexible, and a PET (polyethylene terephthalate) film or the like is selected, but some products use a glass plate having a thickness of about 0.2 mm.
[0006]
Various adhesives such as a low temperature curing type and a UV curing type are used as the adhesive 13 for joining the glass substrate 1 and the transparent film 6, and a gap of 100 to 200 μm is provided between the glass substrate 1 and the transparent film 6 for bonding. To do. In the case of using a thin glass plate as the transparent film 6, the gap is set to 10 to 20 μm.
[0007]
The transparent electrode 2 and the transparent electrode 7 are indium tin oxide (ITO) films doped with tin, and these electrodes are formed by vacuum deposition, sputtering, CDV, printing, or the like. The transparent electrodes 2 and 7 are required to have a high resistance value, and are therefore formed very thin in the range of 250 to 500 angstroms. These are first formed on the entire surface of the substrate by removing unnecessary portions by photolithography and leaving necessary portions.
[0008]
The connection electrodes 3, 4, 8, 9 and 10, 11 are for applying a voltage to the transparent electrodes 2, 7 and are formed by printing silver paste. In view of the performance of the touch panel, the lower the resistance value of these connection electrodes, the better. In general, the sheet resistance value of the connection electrode needs to be 1/100 or less of the sheet resistance value of the transparent electrode. Has been. Therefore, the resistance value is designed to be reduced by increasing the printing thickness of the connection electrode or increasing the width.
[0009]
FIG. 6 shows a state in which the connection electrodes 3, 4, 8 and 9 are formed on the sides of the transparent electrodes 2 and 7, and is an enlarged view of a portion surrounded by a small ellipse at the left end of FIG. . Although the thickness h and width w of the connection electrodes 3, 4, 8, and 9 vary depending on the size of the touch panel, the thickness h is generally designed in the range of 10 to 30 μm and the width w is 1 to 10 mm.
[0010]
3 and 4, the spacers 5 arranged on the transparent electrode 2 of the glass substrate 1 are arranged at almost constant intervals by a method such as printing of acrylic resin, epoxy resin, urethane resin, or other transparent resin material. Is formed. In FIG. 7, when the touch panel of the small device is pressed with the pressing rod 15 and the transparent electrode 7 of the transparent film 6 is brought into contact with the transparent electrode 2 of the glass substrate 1, the contact between the transparent electrodes occurs only at the pressed portion. , Play a role to keep out of its surroundings. The spacer 5 is required to have an invisible size, and those having a diameter of 20 to 30 μm and a height of about 10 μm are provided at intervals of 1 to 2 mm.
[0011]
[Problems to be solved by the invention]
The conventional touch panel as described above has the following problems.
1) Although the connection electrode is formed of silver paste, the width and thickness must be increased in order to reduce the resistance value as described above, which increases the overall outer shape of the touch panel. The conventional touch panel has an active area (effective use area) area of 40 to 50% with respect to the outer area, and expansion of the active area area and downsizing of the touch panel are limited.
2) The upper and lower transparent electrodes are exposed and are in contact with the air, so that they change in quality and change in resistance value over time, resulting in functional problems.
3) Since the transparent electrode is required to have a high resistance value, it is formed very thin in the range of 250 to 500 angstroms. However, even if the resistance value is further increased, if the thickness is made thinner than this, the dispersion of the resistance value increases and the touch panel is increased. There was a limit.
[0012]
4) The transparent film is highly flexible at the center, but the vicinity of the outer seal is bonded to the glass substrate with an adhesive and is difficult to bend. It is not uniform. In addition, the presence of the spacer also affects the pressing force, and even in the vicinity of the center part, no significant force is required until the transparent film bends and reaches the spacer, but the rigidity increases after touching the spacer, and the transparent electrodes A little stronger pressing force is required to contact the two. In particular, a strong pressing force is required in the structure using a glass plate for the transparent film.
This invention solves the 4th problem among the above, and provides the touch panel excellent in performance and reliability.
[0013]
[Means for Solving the Problems]
In the present invention, the transparent electrode formed on the glass substrate and the transparent electrode formed on the transparent film are disposed to face each other with a gap, and a plurality of spacers and a plurality of spacers are formed on the transparent electrode formed on the glass substrate. In a touch panel provided with conductive balls and joined to the outer periphery of the panel, the outer periphery of the transparent film and the glass substrate is sealed with an adhesive so that the conductive ball has the same pressing force as that of the central part of the panel. It is characterized in that it is arranged in the peripheral part, which is an area near the joint part .
In addition, the conductive balls arranged in the peripheral portion are characterized in that the ball diameter becomes smaller toward the inside of the panel.
Thus, when the vicinity of the joint portion of the touch panel is pressed, the transparent electrode of the transparent film is brought into contact with the conductive ball before touching the transparent electrode of the glass substrate. In other words, the same effect as that obtained by reducing the distance between the transparent electrodes at the peripheral portion of the joint portion was obtained. It will operate with pressure, and an almost uniform operational feeling can be obtained at each part of the touch panel surface.
[0014]
As another means of the present invention, a transparent electrode formed on the glass substrate and a transparent electrode formed on the transparent film are arranged to face each other with a gap, and a plurality of the transparent electrodes formed on the glass substrate are arranged. A touch panel comprising a spacer and a plurality of conductive balls, wherein the outer peripheral part of the panel is joined, the conductive ball has a ball diameter that decreases from the peripheral part of the joint part of the panel to the central part of the panel. And
That is, when the center of the panel is pressed, the rigidity increases when the transparent film hits the spacer, and it is necessary to press more force to bring the transparent electrodes into contact with each other, but by providing a conductive ball also in the center, After the transparent film hits the spacer, the transparent electrode touches the conductive ball and becomes conductive with a slight push, and a smooth operation feeling is obtained.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a touch panel in which a large number of conductive balls 25 are provided on a transparent electrode 2 on a glass substrate 1 according to the present invention. FIG. 1 (A) is a plan view, and FIG. FIG. As the conductive ball 25, a plastic ball or glass ball whose surface is coated with a conductive metal film, or a metal ball is used. As described above, the distance between the transparent electrodes 2 and 6 is 100 to 200 μm, the spacer 5 has a diameter of 20 to 30 μm and a height of about 10 μm, while the conductive ball 25 has a diameter of 7 to 10 μm. The conductive balls 25 are mixed with a resin adhesive and arranged by screen printing or the like.
[0016]
Since the peripheral part of the panel is close to the joint part by the adhesive 13, the transparent film 6 is not easily deformed. In the conventional case, the transparent electrodes 2 and 7 do not conduct unless pressed with a considerably large force. By providing the conductive ball 25, the transparent electrode 7 of the transparent film 6 contacts the conductive ball 25 with a slight displacement after hitting the spacer 5. There is no need to make it bigger. Since the transparent film 6 is more easily deformed in the central portion than in the outer peripheral portion, when the conductive balls 25 are provided in rows from the respective sides of the panel as shown in FIG. It is preferable to make the operation feeling uniform.
[0017]
FIG. 2 shows a plan view of another embodiment of the present invention. In the embodiment of FIG. 1, the conductive balls 25 are disposed only in the peripheral portion, whereas in this embodiment, the conductive balls are disposed on the entire surface of the touch panel at an appropriate interval. In order to avoid complication, the spacers are not shown. Although the central portion of the transparent film 6 is easier to press than the peripheral portion, the pressing force increases after it is still pressed and contacts the spacer. This is particularly remarkable when the transparent film 6 is made of a thin glass material. Providing conductive balls not only in the peripheral part but also in the central part is effective in making the pressing force uniform over the entire surface.
[0018]
In the embodiment of FIG. 2, the transparent film 6 is a thin glass plate, the gap between the substrates is 15 μm, and the spacers having a height of about 10 μm are provided at intervals of 1 to 2 mm. The conductive ball 25a outside the two-dot chain line in the figure has a diameter of 10 μm, and the conductive ball 25b inside the frame has a diameter of 5 μm. If the diameter of the conductive ball 25b in the central region is provided in a range of, for example, 3 to 5 μm and the peripheral portion is provided in a range of 10 μm or more, and the diameter of the conductive ball increases from the center toward the periphery, the touch panel Although the pressing force can be made fine and uniform over the entire surface, if the number of types of the conductive ball diameter is increased too much, the number of printing steps increases and the cost increases. Therefore, it is preferable to control the conductive ball diameter to two or three types.
[0019]
【The invention's effect】
As described above, the touch panel according to the present invention is the same when pressing at the central part where the transparent film is easily deformed or when pressing at the peripheral part which is difficult to deform because it is bonded to the glass substrate with an adhesive. In addition to being able to operate with such a pressing force, there is no need to further press the transparent film after the transparent film comes into contact with the spacer, and a favorable touch with a moderate click feeling is obtained.
[Brief description of the drawings]
FIG. 1A is a plan view of an embodiment of the present invention, and FIG.
FIG. 2 is a plan view of another embodiment of the present invention.
3A is a plan view of a conventional touch panel, and FIG. 3B is a sectional view taken along line BB of FIG.
FIG. 4 is a plan view of a glass substrate of a conventional touch panel.
FIG. 5 is a plan view of a transparent film of a conventional touch panel.
FIG. 6 is an enlarged cross-sectional view showing a relationship between a transparent electrode and a connection electrode of a conventional touch panel.
FIG. 7 is a cross-sectional view showing the operation of a conventional touch panel.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Glass substrate 2, 7 Transparent electrode 3, 4, 8, 9, 10, 11 Connection electrode 5 Spacer 6 Transparent film 12 Terminal electrode part 13 Adhesive 25 Conductive ball

Claims (4)

The transparent electrode formed on the glass substrate and the transparent electrode formed on the transparent film are arranged to face each other with a gap, and a plurality of spacers and a plurality of conductive balls are provided on the transparent electrode formed on the glass substrate. In the touch panel where the outer periphery of the panel is joined,
The conductive ball is disposed in a peripheral portion which is a region near the joint portion where the outer periphery of the transparent film and the glass substrate is sealed with an adhesive so as to have the same pressing force as the pressing force in the central portion of the panel. Touch panel.   The touch panel according to claim 1, wherein the conductive ball has a ball diameter that decreases toward an inner side of the panel. The transparent electrode formed on the glass substrate and the transparent electrode formed on the transparent film are arranged to face each other with a gap, and a plurality of spacers and a plurality of conductive balls are provided on the transparent electrode formed on the glass substrate. In the touch panel where the outer periphery of the panel is joined,
The touch panel according to claim 1, wherein a diameter of the conductive ball decreases from a peripheral portion of the joint portion of the panel to a central portion of the panel.   4. The touch panel according to claim 1, wherein the conductive ball is a plastic ball or glass ball coated with a conductive metal film, or a conductive metal ball.

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