JP2002342016A - Ultrasonic touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To uniformize the attenuation amount of ultrasonic waves generated in an adhesive layer between each ultrasonic transducer and a non-piezoelectric substrate and to improve the read accuracy of an ultrasonic touch panel. SOLUTION: In the ultrasonic touch panel for which the ultrasonic transducer 1 including a piezoelectric material 2 for which an interdigital electrode 3 is formed on a surface is provided facing one of the surfaces of the non- piezoelectric substrate 4, by mixing a spacer 6 keeping a fixed interval in an adhesive material 5 adhering the ultrasonic transducer 1 and the non- piezoelectric substrate 2, the film thickness of the adhesive layer is uniformized and the attenuation of the ultrasonic waves generated between each ultrasonic transducer and the non-piezoelectric substrate is uniformized. Thus, sensitivity and read accuracy at the time of the contact of a finger or an indicator are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultrasonic touch panel provided with an ultrasonic transmitting / receiving device on a non-piezoelectric substrate to detect contact of a finger or an object with the non-piezoelectric substrate.

[0002]

2. Description of the Related Art As a method of bonding an ultrasonic transducer in a conventional ultrasonic touch panel, a thermosetting adhesive or an ultraviolet curing adhesive is applied between the ultrasonic transducer and a non-piezoelectric substrate such as glass, or is fixed by a dispenser. A method of dropping an amount and bonding was common.

[0003]

In the conventional method of bonding an ultrasonic transducer in an ultrasonic touch panel,
Since the thickness of the adhesive layer cannot be accurately controlled, the amount of attenuation in the adhesive layer becomes nonuniform, which affects the propagation characteristics of ultrasonic waves from the ultrasonic transducer to the non-piezoelectric substrate.

In addition, since it is necessary to apply a load in bonding the ultrasonic transducer and the non-piezoelectric substrate, when the thickness of the adhesive layer becomes thinner than necessary, excess adhesive protrudes to the side of the ultrasonic transducer. There is a possibility that the propagation characteristics of the surface acoustic wave may be adversely affected, and it is necessary to remove the excess adhesive.

[0005]

Means for Solving the Problems As means for solving the above problems, there is provided an ultrasonic transducer made of a piezoelectric material and having interdigital electrodes formed on the surface thereof, and a predetermined electrode is provided between the ultrasonic transducer and the non-piezoelectric substrate. The ultrasonic transducer was adhered so as to have an adhesive layer including a spacer for maintaining the interval.

As a means for solving the above-mentioned problems, a non-piezoelectric substrate comprising an ultrasonic transducer made of a piezoelectric material and having IDTs formed on the surface thereof and serving as a propagation path of a surface acoustic wave propagating between the ultrasonic transducers is provided. And an ultrasonic touch panel for detecting the position of the finger or indicator based on a change in surface acoustic waves due to contact between the non-piezoelectric substrate and the finger or indicator, wherein a predetermined distance is established between the ultrasonic transducer and the non-piezoelectric substrate. The ultrasonic touch panel was configured so as to have an adhesive layer including a spacer for maintaining the distance between the substrates.

As means for solving the above problems, an ultrasonic transducer made of a piezoelectric material and having interdigital electrodes formed on the surface thereof is disposed opposite to one surface of the non-piezoelectric substrate. The propagation paths of the surface acoustic waves propagating between the transducers are arranged so as to intersect with each other, the interdigital electrodes of the ultrasonic transducer are selected by a selection circuit, and based on a change in the surface acoustic waves due to the contact of a finger or an indicator, In the ultrasonic touch panel for detecting the position of the finger or the indicator, the ultrasonic touch panel is configured to have an adhesive layer including a spacer for maintaining a predetermined interval between the ultrasonic transducer and the non-piezoelectric substrate.

As a means for solving the above problems, a non-piezoelectric substrate comprising an ultrasonic transducer made of a piezoelectric material and having IDTs formed on the surface thereof and serving as a propagation path of a surface acoustic wave propagating between the ultrasonic transducers. In the ultrasonic touch panel for detecting the position of the finger or the indicator based on the change of the surface acoustic wave due to the contact between the non-piezoelectric substrate and the finger or the indicator, the surface is connected to the interdigital electrode or the interdigital electrode. An ultrasonic transducer having an electrode part and an ITO (Indium Tin Oxi)
de) or a non-piezoelectric substrate having an electrode portion made of a conductive material such as aluminum, a function of maintaining a predetermined distance between the ultrasonic transducer and the non-piezoelectric substrate, and interdigital electrodes or An ultrasonic touch panel such that a conductive spacer having a function of electrically connecting an electrode portion connected to the interdigital electrode and an electrode portion of the non-piezoelectric substrate is included in an adhesive layer between the ultrasonic transducer and the non-piezoelectric substrate. Was configured.

[0009]

FIG. 1 is a sectional view of an ultrasonic touch panel according to an embodiment of the present invention. 1 is an ultrasonic transducer, 2 is a piezoelectric material such as PZT, 3 is an interdigital electrode formed on the surface of the piezoelectric material, 4 is a non-piezoelectric substrate such as glass for transmitting surface acoustic waves, 5 is an adhesive, 6 is a spacer.

FIG. 2 shows an arrangement of the ultrasonic transducers in the ultrasonic touch panel.

The ultrasonic transducers 1 are arranged to face each other with the transmitting side being a transmitting side ultrasonic transducer Tn and the receiving side being a receiving side ultrasonic transducer Rn. The presence / absence of the contact and the designated position are calculated.

FIG. 3 shows a procedure of a method of bonding the ultrasonic transducer and the non-piezoelectric substrate. First, the adhesive 5 and the spacer 6 are mixed and degassed. Using a dispenser, a fixed amount is discharged onto the non-piezoelectric substrate, an ultrasonic transducer is arranged and bonded, and thereafter, a load is applied and heat curing is performed.

Here, regarding the ultrasonic touch panel prepared under the above conditions, in order to evaluate the influence on the propagation characteristics of the surface acoustic wave, the transmitting side ultrasonic transducer T
The insertion loss between n and the receiving ultrasonic transducer Rn is measured.

As a comparative example in which no spacer is used, PZT (12 mm × 6 mm × 0.23 m) is used as a piezoelectric material.
m) is used to form an interdigital electrode (six electrode pairs, electrode spacing 0.25 mm) on the surface of the piezoelectric material, and a soda lime glass (85 mm × 30 mm × 0.7mm), One-part thermosetting type XNR4203 manufactured by Nagase & Co., Ltd. is used as the adhesive, and the center distance between the transmitting and receiving ultrasonic transducers is 27m.
m, and an ultrasonic touch panel was created as shown in FIG.

On the other hand, as an example, 0.5% by weight of Micropearl SP (particle size: 4 μm) manufactured by Sekisui Fine Chemical Co., Ltd. was mixed as a spacer into an adhesive to produce an ultrasonic touch panel as shown in FIG. .

First, evaluation of insertion loss will be described. For information on how to evaluate insertion loss, see Hewlett Packard
Using a network analyzer 8153B manufactured by the company, a transmitting ultrasonic transducer is connected to the output, a receiving ultrasonic transducer is connected to the input, and the transmitting ultrasonic transducers T1 to T5 and the receiving ultrasonic transducer R1 to R5 at 6 MHz are connected. Was measured.

Table 1 shows the measurement results of the insertion loss between the transducers.

[0018]

[Table 1]

Next, the evaluation of the thickness of the adhesive layer will be described. Regarding the evaluation method of the film thickness of the adhesive layer, the cross section including the adhesive layer was polished with alumina, and the end face was measured with a metallographic microscope.

Table 2 shows the measurement results of the thickness of the adhesive layer between each ultrasonic transducer and the glass substrate.

[0021]

[Table 2]

FIG. 4 shows the relationship between the average value of the thickness of the adhesive layer and the insertion loss between the ultrasonic transducers. The standard deviation of the film thickness of the comparative example shown in FIG. 4 is larger than the film thickness of the example, and the insertion loss tends to be worse as the film thickness is larger.

Based on the results in Table 2, the thickness of the adhesive layer was made uniform by using the spacers. Further, from the results in Table 1, the standardized insertion loss was obtained by the structure of the embodiment in which the film thickness was made uniform. Since the deviation is reduced, it can be understood that controlling the thickness of the adhesive layer is effective for improving the characteristics of insertion loss, and for improving the sensitivity and reading accuracy at the time of contact with a finger or an indicator.

In the present invention, the thickness of the adhesive layer can be controlled by using a two-component thermosetting adhesive or an ultraviolet-curing adhesive instead of the above-mentioned adhesive, and the insertion loss characteristics can be controlled. It is effective for improvement.

Next, a second configuration using conductive spacers so as to maintain the gap between the adhesive layer between the ultrasonic transducer and the non-piezoelectric substrate and to ensure conduction will be described with reference to FIGS. I do.

FIG. 5 is a perspective view showing the interdigital transducer 3 formed on the lower surface of the piezoelectric material 2 before bonding and the electrode portion 9 formed on the upper surface of the non-piezoelectric substrate 4.

FIG. 6 is a sectional view showing a second configuration using a conductive spacer.

Reference numeral 1 denotes an ultrasonic transducer, which includes a piezoelectric material 2 such as PZT, and interdigital electrodes 3 formed on the surface of the piezoelectric material. Reference numeral 4 denotes a non-piezoelectric substrate made of glass or the like that propagates surface acoustic waves, 5 denotes an adhesive, and 8 denotes a conductive spacer. Reference numeral 9 denotes an electrode portion made of ITO or the like formed on a non-piezoelectric substrate.

Ultrasonic transducer 1 and non-piezoelectric substrate 4
When the conductive spacers are used for bonding, the IDTs 3 and the electrode portions 9 can be electrically connected. Therefore, in addition to the improvement of the insertion loss characteristics by controlling the thickness of the adhesive layer, it is possible to reduce the amount of wire bonding and the amount of the flexible substrate used and the number of steps.

Finally, a third configuration using an ultrasonic transducer including a plurality of interdigital electrodes will be described with reference to FIG.

1 is an ultrasonic transducer, 2a is PZ
A piezoelectric material 3 such as T is an interdigital electrode formed on the surface of the piezoelectric material. Reference numeral 4 denotes a non-piezoelectric substrate made of glass or the like for transmitting a surface acoustic wave. A single piezoelectric material surface includes a plurality of interdigital transducers, each of which selects an opposing interdigital transducer, and electrically detects the propagation characteristics between the transmitting side and the receiving side ultrasonic transducers. It is determined whether or not the indicator has been touched.

Also in the third configuration, if the thickness of the adhesive layer varies, a large difference occurs in the propagation characteristics depending on the selected IDT. Therefore, the thickness of the adhesive layer is made uniform by using a spacer to improve the propagation characteristics. By making it uniform,
It is possible to improve the sensitivity and reading accuracy of the finger or the indicator.

[0033]

According to the present invention, by providing the adhesive layer including the spacer between the ultrasonic transducer and the non-piezoelectric substrate, the attenuation rate of the ultrasonic wave is low, and the variation of the insertion loss between the ultrasonic transducers is reduced. Since the number is reduced, the sensitivity at the time of contact with the finger or the indicator is improved, and the reading accuracy of the position indicated by the finger or the indicator can be improved. Furthermore, by providing an adhesive layer including a conductive spacer between the ultrasonic transducer and the non-piezoelectric substrate, it is possible to reduce the number of electrical connection steps such as wire bonding, thereby reducing costs. Becomes

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an ultrasonic touch panel according to the present invention.

FIG. 2 is a schematic diagram showing a configuration of an ultrasonic touch panel according to the present invention.

FIG. 3 is an explanatory view showing a method of bonding an ultrasonic transducer and a non-piezoelectric substrate.

FIG. 4 is a graph showing the relationship between the thickness of an adhesive layer and insertion loss.

FIG. 5 is a perspective view showing an electrode arrangement of an ultrasonic touch panel using a conductive spacer.

FIG. 6 is a cross-sectional view illustrating a configuration of an ultrasonic touch panel using a conductive spacer according to the present invention.

FIG. 7 is a schematic diagram showing a configuration of an ultrasonic touch panel including an ultrasonic transducer including a plurality of interdigital electrodes according to the present invention.

FIG. 8 is a cross-sectional view illustrating a configuration of a conventional ultrasonic touch panel.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Ultrasonic transducer 2, 2a ... Piezoelectric material 3 ... Interdigital electrode 4 ... Non-piezoelectric substrate 5 ... Adhesive 6 ... Spacer 7 ... Finger 8 ... Conduction Spacer 9 ・ ・ ・ Electrode part Tn ・ ・ ・ Transmitting ultrasonic transducer Rn ・ ・ ・ Receiving ultrasonic transducer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Fumio Kimura 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Prefecture Inside SIIR D Center (72) Inventor Takashi Sarada 1 Nakase, Mihama-ku, Chiba-shi, Chiba 8-8 chome S.I.R.D Center Center (72) Inventor Masataka Shinogi 1-8-8 Nakase, Mihama-ku, Chiba-shi, Chiba Seiko Instruments Inc. (72) Inventor Koji Toda Futaba, Yokosuka-shi, Kanagawa 1-49-18 Toda Kojinai F-term (reference) 5B068 AA04 AA32 BB22 BC03 BC07

Claims (4)

[Claims] An ultrasonic wave comprising an ultrasonic transducer made of a piezoelectric material and having interdigital electrodes formed on a surface thereof, and having an adhesive layer including a spacer for maintaining a predetermined distance between the ultrasonic transducer and a non-piezoelectric substrate. Transducer bonding method. 2. A non-piezoelectric substrate which includes an ultrasonic transducer made of a piezoelectric material and has IDTs formed on the surface thereof, and serves as a propagation path of a surface acoustic wave propagating between the ultrasonic transducers. Or, in an ultrasonic touch panel for detecting the position of the finger or the indicator based on a change in the surface acoustic wave due to the contact of the indicator, including a spacer for maintaining a predetermined interval between the ultrasonic transducer and the non-piezoelectric substrate An ultrasonic touch panel having an adhesive layer. 3. An ultrasonic transducer made of a piezoelectric material and having an interdigital transducer formed on the surface thereof is disposed facing one surface of a non-piezoelectric substrate, and the surface acoustic wave propagates between the opposed ultrasonic transducers. Are arranged so that the propagation paths intersect each other, the interdigital transducer of the ultrasonic transducer is selected by a selection circuit, and the position of the finger or the indicator is determined based on a change in the surface acoustic wave caused by the contact of the finger or the indicator. An ultrasonic touch panel, comprising: an adhesive layer including a spacer for maintaining a predetermined distance between an ultrasonic transducer and a non-piezoelectric substrate. 4. A non-piezoelectric substrate including an ultrasonic transducer made of a piezoelectric material and having interdigital electrodes formed on the surface thereof, and serving as a propagation path of a surface acoustic wave propagating between the ultrasonic transducers. Or, in an ultrasonic touch panel for detecting the position of the finger or the indicator based on a change in surface acoustic waves caused by contact of the indicator, an ultrasonic transducer having an interdigital electrode or an electrode portion connected to the interdigital electrode on the surface. And IT on the surface
A non-piezoelectric substrate having an electrode portion made of a conductive material such as O (Indium Tin Oxide) or aluminum; a function of maintaining a predetermined distance between the ultrasonic transducer and the non-piezoelectric substrate; A conductive spacer having a function of electrically connecting an interdigital electrode or an electrode portion connected to the interdigital electrode and the electrode portion of the non-piezoelectric substrate may be included in an adhesive layer between the ultrasonic transducer and the non-piezoelectric substrate. Ultrasonic touch panel.