Computer graphics processing and selective visual display system – Display peripheral interface input device – Touch panel
Reexamination Certificate
2002-01-25
2004-07-27
Mengistu, Amare (Department: 2673)
Computer graphics processing and selective visual display system
Display peripheral interface input device
Touch panel
C345S017000
Reexamination Certificate
active
06768484
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a touch panel device for detecting a touch thereon of a finger or an object such as pen, more specifically to a touch panel device wherein an interdigital transducer (hereinafter referred to as “IDT”) is used, for detecting a touched position by sensing an attenuation or break of surface acoustic wave (hereinafter referred to as “SAW”).
Along with the growing popularity of computer systems mainly represented by personal computers, devices for inputting new information or giving various instructions to a computer system by touching a finger or pen on a screen of a display device on which information is displayed by a computer system have come to be widely utilized. When inputting operation is executed by a touching method in response to information displayed on a screen of a display device of a personal computer etc., a touched position (indicated position) has to be detected with a high accuracy.
Among touch panel devices for detecting a position touched by a finger or pen, those provided with resistance film and those in which ultrasonic wave is used are being popularly utilized. The former having a resistance film detects a change of partial ratio of voltage caused by a touch of an object on the resistance film. A device of this type has an advantage of low power consumption, but has a disadvantage in such aspects as response time, detection performance and durability.
On the other hand, a device in which ultrasonic wave is utilized propagates SAW on for instance a non-piezoelectric substrate, so that a position touched by an object is detected by sensing an attenuation of SAW caused by a touch of an object such as a pen on the non-piezoelectric substrate. The inventors of the present invention have been pursuing studies and development of a touch panel device, wherein IDT that can be formed in a batch by a photolithography technique is used as a transducer for exciting or receiving SAW. In the mentioned touch panel device, an element constituted by IDT and piezoelectric thin film is employed as an excitation element for exciting of SAW or a receiving element for receiving the propagated SAW.
FIG. 1
is a schematic drawing showing a configuration of a conventional touch panel device wherein IDTs are used in the mentioned manner. Referring to
FIG. 1
, reference numeral
60
stands for a rectangular non-piezoelectric substrate made of forinstance a glass material, and on one of the respective end portions of X-direction and Y-direction of non-piezoelectric substrate
60
, a plurality of excitation elements
65
consisting of input IDT and piezoelectric thin film for exciting SAW are aligned in such a manner that each of them corresponds to each of a plurality of tracks. Also, on the other respective end portions of X-direction and Y-direction of non-piezoelectric substrate
60
, a plurality of receiving elements
66
consisting of output IDT and piezoelectric thin film for receiving SAW are aligned so as to confront excitation elements
65
.
In a touch panel device of
FIG. 1
, electric signals are inputted to each of excitation elements
65
to excite SAW so that SAW is propagated on the non-piezoelectric substrate
60
, and each of receiving elements
66
receives the propagated SAW. And when an object touches on a propagating route of SAW on the non-piezoelectric substrate
60
, SAW is attenuated. Therefore whether and a position where an object touched can be detected by sensing whether an attenuation of signal level received by the receiving elements
66
has taken place.
Also, the inventors of the invention offer a touch panel device wherein excitation elements and receiving elements are disposed so as to propagate SAW diagonally (along diagonal lines).
FIG. 2
is a schematic drawing showing a configuration of electrodes of the mentioned touch panel device. Referring to
FIG. 2
, numeral
70
stands for a rectangular non-piezoelectric substrate made of for instance a glass material, and a central area surrounded by broken lines is a detecting region
70
a
where a touched position can be detected.
In the frame region outside of the detecting region
70
a
, which corresponds to the peripheral area of non-piezoelectric substrate
70
, four IDTs
71
are placed. Each IDT
71
is provided with bus electrodes
72
,
72
confronting each other and respectively comprising comb-like electrode fingers
73
that are bent halfway and alternately aligned. By such an arrangement, a row of comb-like electrode fingers
73
inclined in two directions from the confronting direction of bus electrodes
72
,
72
is formed, which enables excitation of SAW in two directions and reception of SAW from two directions. In this example, IDTs
71
on the upper and lower sides are functioning as excitation elements for exciting SAW in two different directions at a time, while IDTs
71
on the left and right sides as receiving elements for receiving SAW from two different directions.
On the upper and lower sides, terminals
74
,
74
for inputting and grounding connected to bus electrodes
72
of the respective IDTs
71
are provided. Also, terminals
74
,
74
for outputting and grounding connected to bus electrodes
72
of the respective IDTs
71
are provided on the left and right sides. And to each of terminals
74
, each of leading lines
77
is connected.
FIG. 3
is a schematic drawing of a flexible substrate
78
corresponding to FIG.
2
. On the flexible substrate
78
a conductor pattern
79
is formed at a position corresponding to leading lines
77
. And when such flexible substrate
78
is placed over a configuration of electrodes shown in
FIG. 2
, a touch panel device is constituted.
It is advantageous from a viewpoint of mounting process to utilize the flexible substrate
78
for drawing out signals from a touch panel device. As shown in
FIGS. 2 and 3
, IDTs
71
surrounded by long-sized bus electrodes
72
are disposed on the sides in the frame region closer to the detecting region
70
a
, around which leading lines
77
are disposed, and all leading lines
77
are united at one side. Leading lines
77
united in this way are connected to an exterior circuit through the conductor pattern
79
on the flexible substrate
78
. Now, since the frame region is an area where a touched position cannot be detected, it is a critical factor for enhancing a product value to minimize the area of the frame region, and for such a purpose it is essential to narrow the width of bus electrodes
72
and leading lines
77
.
In a conventional configuration as shown in
FIGS. 2 and 3
, a problem is that intensity of received SAW is lowered due to a resistance loss that is caused while a signal is transmitted through each of long-sized bus electrodes of IDTs placed all over the panel. In order to prevent such a resistance loss it is necessary to increase the width of bus electrodes and leading lines, which, however, is contradictory to the purpose of minimizing the area of the frame region. Meanwhile it might be another option to increase film thickness of the mentioned components, but in this case still a problem remains that production process will be more complicated, because the optimum condition of film thickness is different between excitation/reception unit (IDT) and transmission unit (bus electrodes and leading lines).
SUMMARY OF THE INVENTION
An object of the present invention is to provide a touch panel device wherein a resistance loss in a transmission unit can be minimized without enlarging a frame region.
Another object of the invention is to provide a touch panel device wherein the frame region can be further narrowed.
A touch panel device according to the first aspect of the invention comprises IDTs for exciting or receiving SAW placed on a peripheral area of a substrate, in which comb-like electrode fingers are aligned along bus electrodes confronting each other in a direction that is aligned with a direction from the center toward the periphery of the substrate, and at least one drawing electrode connected to the bus electrod
Katsuki Takashi
Nakazawa Fumihiko
Sano Satoshi
Takahashi Yuji
Mengistu Amare
Westerman Hattori Daniels & Adrian LLP
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