This application claims benefit of the Japanese Patent Application No. 2006-325611 filed on Dec. 1, 2006, the entire content of which is hereby incorporated by reference.
1. Field of the Invention
The present invention relates to a method of manufacturing a capacitive input device that detects a variation in capacitance using plane electrodes when an operating body, such as a finger, approaches or comes into contact with the electrodes, and more particularly, to an input device including a shield layer for reducing the influence of radiation noise generated from the inside of an electronic apparatus and to a method of manufacturing the same.
2. Description of the Related Art
JP-T-2003-511799 discloses a transparent capacitive sensor. For example, as shown in
In general, an electronic apparatus varies a voltage or current in order to transmit signals. When a voltage or current varies, electromagnetic waves (radiation noise) are generated from transmission lines. When a large amount of radiation noise is generated, the sensor close to the transmission lines is greatly affected by the radiation noise, which causes the accuracy of the sensor to be lowered. Therefore, preferably, a shield layer formed of a transparent conductor that is connected to the ground is provided between the sensor and the electric circuit in order to reduce the influence of the radiation noise on the sensor.
However, in a method of manufacturing the sensor disclosed in JP-T-2003-511799, first, the X and Y conductor traces are separately formed on two transparent base substrates, and the two transparent base substrates are bonded to each other with an insulator interposed therebetween, which makes it difficult to reduce a manufacturing cost.
In an embodiment, a capacitive input device using plane electrodes is disclosed that can operate stably and a method of manufacturing the input device.
According to an aspect of the disclosure, an input device includes: a base substrate; conductive films that are formed on front and rear surfaces of the base substrate; a plurality of electrodes that are formed on the front surface of the base substrate and are partitioned in a predetermined shape by a plurality of partitioning grooves The electrodes serve as sensing units for detecting a variation in capacitance between an operating body and the electrodes. A plurality of electrodes are formed on the rear surface of the base substrate in the same shape and the same array as those of the electrodes formed on the front surface such that they are electrically connected to each other.
According to the above-mentioned structure, the electrodes formed on the front surface of the base substrate and the electrodes formed on the rear surface of the base substrate have the same shape and the same array. Therefore, it is possible to set the capacitance C of each of the sensing units composed of the electrodes to be equal to or greater than a predetermined value, and thus achieve a touch sensor having high stability.
According to another aspect of the invention, there is provided a method of manufacturing an input device including sensing units that detect a variation in capacitance between an operating body and the sensing units. The method includes: forming conductive films on front and rear surfaces of a base substrate; radiating a laser beam onto the conductive films to form partitioning grooves, thereby forming wiring conductive films and electrodes that are partitioned in predetermined shapes by the partitioning grooves on at least one of the conductive films, the electrodes serving as the sensing units; forming an insulating layer on some of the wiring conductive films that are formed on the one conductive film; forming wiring patterns on the insulating layer so as to be electrically connected to the corresponding electrodes; and forming a conductive pattern on the other conductive film so as to electrically connect the electrodes that are partitioned by the partitioning grooves.
According to the above-mentioned aspect, it is possible to reduce the number of manufacturing processes and thus reduce manufacturing costs.
As described above, the disclosed embodiments can provide a stable capacitive input device without being erroneously operated.
Further, according to the capacitive input device according to the disclosed embodiment, it is possible to shorten the time required to manufacture the input device and reduce the number of manufacturing processes, which results in a low manufacturing cost.
A touch sensor (a capacitive input device using plane electrodes) TS according to this embodiment is provided in an electronic apparatus, such as a mobile phone or a PDA, while being laminated on a display device, such as a liquid crystal display device. The touch sensor detects coordinates of an operating body, such as a finger or a pen, on the display device, and transmits input information to a control unit of an electronic apparatus.
As shown in
The base substrate 1 is formed of a sheet member made of a transparent and insulating material, such as polyethylene terephthalate (PET). It is preferable that the base substrate 1 have plasticity. When the base substrate 1 has plasticity, it is possible to mount the touch sensor TS to a case having a curved surface and thus improve flexibility in mounting the touch sensor TS.
The conductive film 2A is composed of a thin metal film formed of a transparent material, such as ITO, and is formed on an upper surface of the transparent base substrate 1. As shown in
The insulating layer 6 is partially formed between adjacent electrodes 4, that is, on the partitioning grooves 3 or the wiring conductive film 5, at the ends of the conductive film 2A in the directions X1 and X2. A plurality of wiring patterns 7 are formed on the insulating layer 6. One end 7a of each of the wiring patterns 7 is connected to a corresponding one of the electrodes 4a to 4o, and the other ends of the wiring patterns 7 extend to the outside of the touch sensor TS through the flexible cable 12 that is connected to the base substrate 1. A protective layer 9 formed of a transparent resist material covers the conductive film 2A, the insulating layer 6, and the wiring patterns 7, that is, an uppermost layer.
In this embodiment, the conductive film 2B having the same structure as the conductive film 2A is formed on the lower surface of the base substrate 1. That is, the conductive film 2B is composed of a thin metal film formed of a transparent material, such as ITO. The partitioning grooves 3, the electrodes 4, and the wiring conductive films 5 are formed on the conductive film 2B, similar to the conductive film 2A.
As shown in
In this embodiment, the conductive film 2B forms the ground GND, and is interposed between the liquid crystal display device 20 and the electrodes 4a to 4o formed in the conductive film 2A. Therefore, the conductive film 2B serves as a shielding layer that reduces the influence of radiation noise generated from the liquid crystal display device 20 on the sensing units. The conductive film 2B may not include the partitioning grooves 3. That is, the lower surface of the base substrate 1 may be covered with one thin metal film (a so-called ‘solid film’).
In the touch sensor TS, a predetermined voltage is applied between each of the electrodes 4a to 4o forming the conductive film 2A and the conductive film 2B forming the ground GND. In this case, capacitance C is formed between each of the electrodes 4a to 4o formed in the conductive film 2A and the conductive film 2B serving as the ground GND.
When an operating body comes into contact with the surface of the protective layer 9, the capacitance C formed between one of the electrodes 4 of the conductive film 2A that faces the operating body and the conductive film 2B, serving as the ground GND, varies. A detecting circuit (not shown) detects the variation in the capacitance C, which makes it possible to calculate the position (the position on the XY plane) of the operating body.
When the operator holds an electronic apparatus provided with the touch sensor TS with hands, an operating body, such as the operator's finger, comes into contact with the rear surface of the touch sensor TS as well as the front surface. In this case, when the distance between the operating body that contacts with the rear surface of the touch sensor TS and the conductive film 2B that is formed on the rear surface of the base substrate 1 is small, unnecessary capacitive coupling is formed between the operating body and the conductive film 2B, which causes the potential of the conductive film 2B (the potential of the ground GND) to vary. As a result, the detection accuracy of the touch sensor TS is likely to be lowered. For this reason, it is preferable that the distance between the conductive film 2B forming the ground GND and the rear surface of the touch sensor TS which comes into contact with the operating body be large (that is, the thickness of the touch sensor TS is large).
Therefore, in this embodiment, a sensitivity adjusting layer 10 made of a transparent resist material is formed on the surface of the conductive film 2B. According to this structure, even when the operator holds the touch sensor TS with operator's hands, little capacitive coupling is formed between the operating body and the conductive film 2B forming the ground GND, which makes it possible to stabilize the potential of the conductive film 2B. As a result, it is possible to improve the detection accuracy of the touch sensor TS.
Next, a method of manufacturing the touch sensor according to the first embodiment of the invention will be described below.
As shown in
As shown in
In a third process, as shown in
In a fourth process, as shown in
In a fifth process, as shown in
An operable touch sensor TS is manufactured by the first to fifth processes. However, the wiring patterns 7 are exposed from the front surface of the touch sensor TS, and the conductive pattern 8 for the ground GND is exposed from the rear surface of the touch sensor TS. Therefore, a short circuit is likely to occur between the wiring patterns, or dust is likely to be adhered to the wiring patterns, which may cause the deterioration of quality. In order to solve these problems, the following processes are additionally performed.
In a sixth process, as shown in
Then, in a seventh process, as shown in
As described above, according to the method of manufacturing the touch sensor according to the first embodiment, it is possible to effectively manufacture a touch sensor having a high degree of detection accuracy without being erroneously operated.
That is, in the related art, in a first process, a conductive film is formed on one surface of a first base substrate. In a second process, a conductive film is formed on a second base substrate. In a third process, the first base substrate and the second base substrate are bonded to each other. In a fourth process, etching is performed on the conductive film formed on the first base substrate to form partitioning grooves 3, electrodes 4a to 4o, and wiring conductive films 5.
However, according to this embodiment, in the first process, the first and third processes according to the related art are performed at the same time, and a laser is used in the second process, which makes it possible to simultaneously form the partitioning grooves 3, the electrodes 4a to 4o, and the wiring conductive films 5 on both the conductive film 2A and the conductive film 2B. Therefore, the manufacturing method according to this embodiment can considerably reduce the number of manufacturing processes. As a result, according to the manufacturing method of this embodiment, it is possible to shorten the time required to manufacture the touch sensor and reduce manufacturing costs.
In the method of manufacturing the touch sensor according to the first embodiment of the invention, the wiring patterns 7 are formed on the insulating layer 6 (the fourth process shown in
Alternatively, after the conductive films 2A and 2B are formed (the second process), the conductive pattern 8 may be formed on the conductive film 2B (the fifth process), the insulating layer 6 may be formed on the conductive film 2A (the third process), and then the wiring patterns 7 may be formed on the insulating layer 6 (the fourth process).
A touch sensor TS2 (see
Next, a method of manufacturing the touch sensor TS2 according to the second embodiment (a second manufacturing method) will be described with reference to
As shown in
As shown in
In a third process, as shown in
In a fourth process, as shown in
In a fifth process, as shown in
Since the sensitivity adjusting layer 10 is formed with a predetermined thickness, it is possible to set the distance between an operating body that comes into contact with the rear surface of an electronic apparatus provided with the touch sensor TS2 and the conductive pattern 8 for the ground GND such that there is no variation in the potential of the conductive pattern 8. In this way, it is possible to reduce the erroneous operation of the touch sensor TS2 and thus improve the detection accuracy of the touch sensor TS2.
Since the touch sensor TS2 according to the second embodiment is not provided with the insulating layer 6, the thickness thereof is reduced by a value corresponding to the insulating layer 6, as compared to the touch sensor TS according to the first embodiment. In addition, in the method of manufacturing the touch sensor according to the second embodiment, it is not necessary to perform a process of forming the insulating layer 6, unlike the first embodiment. As a result, according to the second embodiment, it is possible to reduce manufacturing costs, as compared to the first embodiment.
Number | Date | Country | Kind |
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2006-325611 | Dec 2006 | JP | national |