KR100889172B1 - Acoustic waves mode touch panel - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a large acoustic wave touch panel obtained by using a glass substrate with less attenuated acoustic waves and a high intensity of a transmission signal. As a propagation medium of acoustic waves, a glass substrate composed of SiO ₂ as a main component and an additional component and having an attenuation coefficient of about 0.25 dB / cm or less is used. The glass substrate has a propagation rate substantially the same as the propagation rate of soda lime glass, and does not substantially include BaO and / or B ₂ O ₃ as additional components. The glass substrate is substantially free of BaO and B ₂ O ₃ and includes Al ₂ O ₃ , ZrO ₂ and SrO, the content of ZrO ₂ is at least 3% by weight, the content of SrO is at least 6.5% by weight, Al ₂ O ₃ and the ratio of ZrO _{2 ZrO 2 / (Al 2 O} 3 + ZrO 2) is from 30 to 100% by weight. The large acoustic wave touch panel reinforced by using such a glass substrate is obtained.

Description

Acoustic Wave Method Touch Panel {ACOUSTIC WAVES MODE TOUCH PANEL}

1 is a conceptual plan view showing an embodiment of an acoustic wave touch panel according to the present invention.

2 is a waveform diagram showing an envelope of a received signal according to the first embodiment.

3 is a schematic diagram illustrating a method of measuring acoustic wave attenuation in a substrate.

4 is a cross-sectional view of a touch panel mounted on a CRT display monitor.

5 is a cross-sectional view of the touch panel used to obtain a projected image.

6 is a cross-sectional view of a safety glass laminate in which an outer glass layer functions as a touch panel substrate.

* Description of the symbols for the main parts of the drawings *

              1: glass substrate 3a, 3b: transmission means

              4a, 4b, 5a, 5b: reflection array 6a, 6b: receiving means

              100,122: Touch Panel 102: CRT (Brown Tube)

              104,112 housing 106 adhesive tape

              108, 114: sealing material 110: reverse projection lens

              118: projector 120: lens

              151: inner layer glass 152a: touch surface

              152: outer layer glass 153: adhesive

The present invention relates to an acoustic wave type touch position sensor, and more particularly, an acoustic wave is generated in a substate, and the acoustic wave propagates within the substrate due to a characteristic delay in a certain range from a transmission signal. The above delay of time relates to a touch panel in which the length of the different paths associated with each axial displacement along one axis of the substrate is expressed. As a result, when the substrate is in contact with the substrate, confusion occurs in the wave, so that it is detected and the displacement in the axial direction in contact with the substrate is obtained. This kind of touch panel is used as a computer input device associated with an image display of a computer.

In general, the touch panel has been used in various fields as an input / output device in combination with a display device such as a CRT, a liquid crystal display (LCD), a plasma display panel (PDP), or a display unit. Currently, commercially available touch panels are mainly resistive, capacitive and acoustic wave touch panels. In the case of using an acoustic wave touch panel, the touch surface can be firmer and clear and large images can be obtained compared to the resistive and capacitive touch panels.

In the resistive and capacitive touch panels, a resistive layer is formed on a substrate. As a preferred substrate material, soda glass (soda lime glass) is selected in terms of strength, optical transparency and price. The resistive layer is necessary to detect information regarding the touch position. In addition, the conventional resistive touch panel is covered with a plastic cover sheet. In most applications these components added to the glass substrate are prone to damage by accident or by failure. Furthermore, the additional components as described above lower the light transmittance and increase the ambient light reflection, thereby degrading the sharpness (visibility) of data and images in the display device.

On the other hand, conventional acoustic wave touch panels have the advantage of having a solid touch surface and high display image quality, and an ultrasonic layer is used to detect coordinate data regarding an input position, thereby forming a resistive layer on a soda-lime glass substrate. There is no need, and no plastic cover sheet is required. Soda-lime glass is widely used to occupy most of the glass produced in the world, is inexpensive in terms of cost, is a substrate material commonly used in acoustic touch panels, has high transparency, and can propagate acoustic waves at ultrasonic frequencies.

On the other hand, display technology is rapidly developed, and large display products are desired. In the case of the resistive and capacitive touch panels, it is difficult to form the same resistive layer as the size of the panel increases. In the case of an acoustic wave touch panel, since a signal (acoustic wave signal) when ultrasonic waves propagate through the substrate is attenuated, the loss of the signal increases as the size of the panel increases. In large acoustic wave touch panels, it is sometimes impossible to provide a sufficient SN (signal / noise) ratio to determine the input position. For this reason, the means which raises SN ratio of an acoustic wave touch panel is needed. There is also a need for products that reduce the amplitude of signals, for example, products with less expensive control electronics, products with reduced area of reflective arrays, products with signal absorbing sealing materials, and the like. In order to meet these demands, it is necessary to increase the SN ratio of the acoustic touch panel.

The acoustic touch position sensor is provided with a transmitter for generating an acoustic wave beam, such as a "Rayleigh" wave, and a corresponding receiver, to attenuate the acoustic wave beam generated by touching the panel. Observe. In addition, converters, cable conductors, and electronic channels are required. Commercially successful acoustic touch panels are being researched to reduce the cost of installing multiple transducers. As a result, the path length of the acoustic wave is relatively long.

Adler's reissued US Pat. No. 33,151 specification is a pioneer patent in the field of commercially successful acoustic wave touch panels. The burst wave generated by the acoustic wave transducer is coupled (coupled) into the sheet-like substrate. These acoustic waves are deflected by 90 [deg.] To the active region of the system by acoustic wave redirection lattice arrays. The redirecting lattice is oriented at 45 ° with respect to the propagation axis of the acoustic wave from the transducer. Such a grating is similar to a mirror partially plated with silver in an optical system. The acoustic waves passing through the active region are in turn redirected towards the output transducer by another lattice train. The coordinate of the touch position is determined by analyzing a time domain in which the received signal is selectively attenuated, and represents a characteristic delay corresponding to a place (coordinate value) touched on the surface. The use of lattice trains greatly reduces the number of transducers required, enabling the manufacture of touch panels at commercially competitive prices. However, since the acoustic waves are deflected many times using the lattice train, the maximum distance at which the acoustic waves must pass through the substrate is greatly increased. In addition, the signal amplitude of the acoustic touch panel is reduced even when the scattering process in the lattice train is low.

As a touch panel having a low acoustic wave loss, for example, WO 96/23292 discloses a touch panel using borosilicate glass and barium-containing glass having a lower acoustic wave loss than soda lime glass. Borosilicate glass is commercially available under the trade names Pyrex (Corning), Tenfax (Schott Glass), and Boron Float (Shortglass). It does not go cracked.

According to the above document, the attenuation coefficients of Rayleigh waves in borosilicate glass and barium-containing glass are 0.74 dB / inch (0.3 dB / cm) and 0.6 dB / inch (0.24 dB / cm), respectively. It is described as smaller than the Rayleigh wave attenuation coefficient of 1.44 dB / inch (0.57 dB / cm). However, since the propagation speed of borosilicate glass is 122,288 inches / cm, which is different from soda lime glass (125,000 inches / cm), the application of borosilicate glass requires redesigning the conventional touch panel designed based on the propagation speed in soda lime glass. Therefore, it is uneconomical. In addition, the attenuation coefficient of the borosilicate glass and the barium-containing glass is still large in view of the demand for large display products and the like.

Moreover, although it is preferable to use a chemically or thermally strengthened glass substrate when enlarging, borosilicate glass cannot be thermally strengthened because its coefficient of thermal expansion is low as 3.25 × 10 ⁻⁶ / K. In addition, since borosilicate glass generally has a low content of sodium ions that can be substituted with potassium ions or does not contain any sodium ions, there is a limit to the extent to which chemical strengthening (curing) is possible.

Ultrasonic waves also take several modes in glass substrates, of which acoustic wave touch panels are called "Raily" waves. Rayleigh waves are essentially confined to a single surface of a sheet of homogeneous non-piezoelectric medium of sufficient thickness. Rayleigh calculated the wavefunction for the mode for a semi-finite medium. Such waves, which induce a perimeter of a surface of a medium of limited thickness, are precisely called "like Rayleigh" waves, but are generally referred to as "Railey waves" and are also referred to herein. In the design and manufacture of touch panels, it is known from experience that it is sufficient to form the thickness of the substrate to be about 4 times or more of Rayleigh wavelength in order to smoothly propagate Rayleigh waves.

In addition, other wave modes used in an acoustic touch panel are described in US Patent No. 5260521, 5234148, 5177327, 5162618, 5072427, and the like. horizontally polarized shear waves and Lamb waves. In general, Rayleigh waves are used because they are relatively sensitive to touch and can propagate on a simple surface of a homogeneous medium.

Accordingly, it is an object of the present invention to provide an acoustic wave touch panel and a glass substrate therefor that can suppress attenuation of acoustic waves in a glass substrate and improve the strength of a transmission signal.

Another object of the present invention is to provide a robust acoustic wave touch panel operating with high reliability and a glass substrate for the same.

Another object of the present invention is to provide an acoustic wave touch panel and a glass substrate therefor, which can be used even when a transducer having a low signal efficiency conversion is used or a sealing material for generating acoustic wave absorption is used.

It is still another object of the present invention to provide a reinforced large acoustic wave touch panel, which can be thermally or chemically strengthened or cured, and a glass substrate therefor.

The present inventors have carefully studied to achieve the above object, and as a result, using a specific glass substrate or substrate as the ultrasonic wave propagation medium can significantly suppress the attenuation of the ultrasonic waves and maintain a high intensity until a signal is received and detected. While discovering that the signal can be transmitted, the present invention has been completed.

That is, the touch panel of the present invention has a glass substrate functioning as a transmission medium for acoustic waves composed of SiO _{2 as a} main component and an additional component, and is a touch panel for detecting coordinate data regarding a contact position, and attenuating the glass substrate. The coefficient is about 0.25 dB / cm or less. The attenuation coefficient is a pair of 0.5 inches in width so as to face a glass sample to be tested with a thickness sufficient to support propagation of the Rayleigh wave at the substrate surface against a Rayleigh wave of 5.53 MHz. A wedge transducer can be mounted and measured via the slope of the plot of amplitude versus distance with respect to the signal. Moreover, the glass substrate has at least one of the properties described in (1) and (2) below:

(1) The propagation velocity is substantially the same as the propagation velocity of soda-lime glass.

(2) the additional component does not contain BaO and / or B ₂ O ₃ or contains very small amounts.

In addition, in the touch panel according to the present invention, the glass substrate is composed of SiO _{2 as a} main component and an additional component, and the additional component has at least one of the properties described in the following (A) to (D):

(A) does not contain BaO or contains very small amounts and comprises at least one component of ZrO ₂ and SrO.

(B) contains no or very small amounts of BaO and B ₂ O ₃ and comprises at least one component of Al ₂ O ₃ , ZrO ₂ and SrO.

(C) ZrO ₂ and at least one component of SrO, the content of ZrO ₂ is at least 3% by weight, the content of SrO is at least 6.5% by weight.

(D) ZrO ₂ and Al ₂ O ₃ , and the ratio of Al ₂ O ₃ and ZrO ₂ is ZrO ₂ / (Al ₂ O ₃ + ZrO ₂ ) = 30 to 100% by weight.

Moreover, the touch panel may be composed of a substrate through which acoustic waves can propagate, a means for introducing the acoustic waves into the substrate, and the substrate may be formed of glass which can be chemically or thermally strengthened.

Moreover, in constructing the acoustic wave type touch panel for detecting the coordinate data concerning the contact position of this invention, a glass substrate has at least one of the characteristics as described in said (1)-(2), (A)-(D). It consists of a glass substrate which has a characteristic.

In describing an acoustic wave touch panel, many terms such as "acoustic wave sensor", "acoustic wave touch screen", and "ultrasound touch panel" are used. In this specification, unless otherwise specified, all of these terms are synonymous, meaning a transparent touch sensor that senses touch through ultrasound and uses a reflective grating array to reduce the number of transducers.

In addition, in this specification, "temperable glass" means glass which can be strengthened by heat or substantially chemically cured. Moreover, "substantially" tempered glass refers to glass that has been chemically cured until its strength is increased to about 50% or more, preferably until it is increased to about 100% or more.

The glass substrate constituting the acoustic wave touch panel for detecting coordinate data on the contact position is composed of SiO _{2 as a} main component and additional components, and is used as an acoustic wave propagation medium.

In one aspect, the invention is characterized in that (1) the propagation speed of the acoustic wave (Rail wave) in the glass substrate is substantially the same as the propagation speed (125,000 inches / cm) of the soda lime glass and furthermore, the damping coefficient is small. Has The propagation speed of the glass substrate is, for example, about 121,000 to 129,000 inches / cm, preferably about 123,000 to 127,000 inches / cm, and more preferably about 124,000 to 126,000 inches / cm. Such glass is available, for example, from Saint-Gobain Co., Ltd. and available under the trade name "CS25" (propagation speed 124,700 inches / cm). Using a glass substrate having a propagation speed approximately equal to that of soda lime glass has the advantage that the same design as that of widely used soda lime glass substrates can be used.

In another aspect, the present invention has the feature that (2) the damping coefficient is small even though the additional components constituting the glass substrate do not substantially contain BaO and / or B ₂ O ₃ .

A glass substrate has the characteristic in any one of said (1) or (2), and can have the characteristic corresponding to both (1) and (2).

In the above aspect (2), the glass substrate as an additional component does not include all of BaO and B ₂ O ₃ preferably includes a very small amount, and further components are, including any of the components of BaO and B ₂ O ₃ In this case, the attenuation coefficient is 0.23 dB / cm or less, preferably 0.20 dB / cm or less.

Glass with a low acoustic wave loss is a pair of 0.5 inches wide that opposes a glass sample to be tested to have a thickness sufficient to support radio wave propagation at the substrate surface against a 5.53 MHz Rayleigh wave. A wedge transducer is mounted and measured by the slope of the plot of amplitude versus distance with respect to the signal and can be defined as glass with an attenuation coefficient (acoustic wave loss) of about 0.25 dB / cm or less.

The attenuation coefficient of the glass substrate is about 0.25 dB / cm or less (for example, about 0.1 to 0.23 dB / cm), preferably 0.22 dB / cm or less (for example, about 0.1 to 0.20 dB / cm), and For example, in the product manufactured by Saint-Gobain, and the brand name "CS25", the average decay rate is 0.46 dB / inch (0.18 dB / cm). Therefore, using the glass substrate of this invention, compared with soda-lime glass (average attenuation rate 1.44dB / inch (0.57dB / cm)), the average attenuation rate can be reduced about 70, and borosilicate glass (made by shot glass company, brand name " Tempax ”, average attenuation of 0.74dB / inch (approximately 0.3dB / cm) can be reduced by about 40, and compared to barium-containing glass (0.6dB / inch (approximately 0.24dB / cm)). The average decay rate can be reduced by about 20.

With the glass substrate of the present invention having substantially less absorption of acoustic waves than glass containing soda lime glass, borosilicate glass and barium, it is possible to substantially increase the signal that can be received by the receiving transducer. In the touch panel having the maximum path length of the acoustic wave of 20 to 40 inches, the use of the "CS25" achieves the same effect as that of the signal of about 12 to 22 dB added to the borosilicate glass. Larger signal gains can be expected when using larger touch panels than current commercial products.

In addition, the attenuation of the acoustic wave is an increase function of the frequency, and can be measured by the Rayleigh wave being attenuated in the glass by the method shown in FIG. That is, paired transmit transducers 2 and receive transducers 4 are placed on glass and the spacing between them is changed to 2 inches, 4 inches and 6 inches. Amplitudes are measured at each interval for two specimens of glass sample of sufficient thickness to support the propagation of Rayleigh waves, and the attenuation coefficient (average decay rate) is measured by the slope of the plotted amplitude versus distance. In the measurement, a 0.5 inch wide wedge transducer and a 5.53 MHz Rayleigh wave are used.

Thus, the glass substrate is an acoustic wave loss is small, can be composed of a main component of SiO ₂ and additional components. The added component has at least one characteristic selected from the above aspects (A) to (D).

In embodiment (A), the added component does not comprise BaO or contains very small amounts and comprises at least one of ZrO ₂ and SrO. Such a glass substrate has a small attenuation coefficient even if it does not contain BaO or contains a very small amount. Furthermore, in order to reduce the damping coefficient, it is preferable to include both ZrO ₂ and SrO.

The absence or very small amount of BaO, whether unavoidable or intentional, means that the BaO content in the glass substrate is, for example, about 0 to 1.5% by weight, preferably about 0 to 1.0% by weight, more preferably 0 It means to about 0.5% by weight.

The content of ZrO _{2 in} the glass substrate is, for example, 1% by weight or more (for example, about 1 to 20% by weight), preferably 3% by weight or more (for example, about 5 to 15% by weight), and more. Preferably it is 7 weight% or more (for example, about 7-15 weight%).

The content of SrO is, for example, 1% by weight or more (eg, about 1 to 20% by weight), preferably 3% by weight or more (eg, about 3 to 15% by weight), more preferably 5 It is weight% or more (for example, about 5 to 15 weight%), Very preferably 6.5 weight% or more (for example, about 6.5 to 15 weight%).

In embodiment (B), the attenuation coefficient can be reduced by configuring the additional component with at least one component selected from Al ₂ O ₃ , ZrO ₂ and SrO even if it contains no or very small amounts of BaO and B ₂ O ₃ . have. The component may be appropriately selected and may be a single component (ZrO ₂ , SrO, etc.), two components may be combined (a combination of SrO and Al ₂ O ₃ , a combination of ZrO ₂ and Al ₂ O ₃ , and a SrO and ZrO ₂₎ . Combination), and the three components may be combined (combination of SrO, ZrO ₂ and Al ₂ O ₃ ), and contain two components (both SrO and ZrO ₂ ) or often contain three components.

The absence of BaO or very small amount is the same as in the above embodiment (A), and the content of ZrO ₂ or SrO in the glass substrate is also the same as the above embodiment (A).

B ₂ O ₃ does not contain a thing that is very include a small amount, the content of B ₂ O _3, for example from 0 to 4% by weight, preferably about 0-2 wt%, and more preferably 0-1% by weight Degree (for example, about 0 to 0.5% by weight).

The content of Al ₂ O ₃ is, for example, 2.5% by weight or more (eg, about 2.5 to 20% by weight), preferably 3.0% by weight or more (eg, about 3.5 to 15% by weight).

In the aspect (C), the acoustic wave loss can be reduced by containing at least one component of ZrO ₂ and SrO in a specific amount. The added component may not contain both components of ZrO ₂ and SrO, or may contain either component of ZrO ₂ and SrO.

The content of ZrO _{2 in} the glass substrate is, for example, 3% by weight or more (eg, about 3 to 20% by weight), preferably 5% by weight or more (eg, about 5 to 15% by weight), more Preferably it is 7 weight% or more (for example, about 7-15 weight%).

The content of SrO in the glass substrate is, for example, 6.5 wt% or more (eg, about 6.5 to 20% by weight), preferably 7.0 wt% or more (eg, about 7.0 to 15% by weight), and more Preferably it is 7.5 weight% or more (for example, about 7.5-15 weight%).

In aspect (D), a glass substrate with few acoustic wave losses can be formed by containing ZrO ₂ and Al ₂ O ₃ at a predetermined ratio.

The ratio of ZrO ₂ and Al ₂ O ₃ (ZrO ₂ / (Al ₂ O ₃ + ZrO ₂ )) is, for example, about 30 to 100 weight, preferably about 40 to 90 weight, more preferably 50 to 80 It is about weight.

Further, in the above embodiments (C) and (D), additional components, and containing a B ₂ O ₃ and / or BaO, or need not contain B ₂ O ₃ and / or BaO.

The embodiment (A) in to (D), if the glass substrate comprises an Al ₂ O ₃ and ZrO _2, the total of the content of Al ₂ O ₃ and ZrO _2, for example 3 to 20% by weight approximately, Preferably it is about 8 to 20 weight%, More preferably, it is about 10 to 20 weight% (for example, about 11 to 20 weight%).

In addition, the components are added and furthermore also contain a K ₂ O, may also contain a Na ₂ O, CaO and MgO. The content of K ₂ O in the glass substrate is, for example, about 5 to 10% by weight, preferably about 6 to 10% by weight.

The total content of Na ₂ O, CaO and MgO in the glass substrate is, for example, about 7 to 20% by weight, preferably about 10 to 20% by weight (eg, about 11 to 20% by weight).

As additional components, metal oxides such as TiO ₂ , B ₂ O ₃ , Y ₂ O ₃ , SnO ₂ , PbO ₂ , In ₂ O _3, and the like may be included as necessary.

The content of SiO _{2 as} the main component is, for example, about 45 to 90% by weight, preferably about 50 to 85% by weight (eg, about 55 to 85% by weight) as the remaining amount of the additional component.

The glass substrate may be formed of various components, for example, oxides (eg, ZnO, BeO, LiO ₂ , TeO ₂ , V ₂ O ₅ , P ₂ O ₅ ), fluxes, clarifiers, It may further contain a coloring agent, a bleaching agent, other components, and the like.

The density of a glass substrate is about 2.6-3.0 g / cm <3>, for example, Preferably it is about 2.7-3.0 g / cm <3> (especially about 2.75-3.0 g / cm <3>). The softening point (10 ^7.6 poise) of a glass substrate is about 800-900 degreeC, for example, Preferably it is about 830-860 degreeC.

The glass substrate of the touch panel according to the present invention is useful for inputting data by touch, and is disposed on the display device and the data displayed by the display device can be viewed through the touch panel. Therefore, the glass substrate which comprises a touchscreen shows the outstanding light transmittance in visible region (wavelength of about 400-700 nm).

The touch panel of the present invention disposed on the display device can be used in combination with a liquid crystal display device, a plasma display panel device, or the like.

1 is a conceptual plan view showing one configuration of a touch panel according to the present invention.

The touch panel has a glass substrate 1 as a radio wave medium which is symmetrical in the X-axis and Y-axis directions and has a touchable display area (image display area) 2. Acoustic waves propagating in the substrate have sufficient power density and are attenuated in the measurable range by touching the surface.

The transmission means 3a, 3b transmit an acoustic wave in the X-axis and Y-axis directions of the glass substrate 1. Such transmission means may have an electroacoustic transducer, for example a ceramic piezoelectric element, and a mode conversion element such as a plastic wedge of a wedge type transducer. These conversion means are arranged at a predetermined position of the glass substrate 1 so as to direct the acoustic wave beam toward the transmission reflection lattice arrays 4a and 4b.

The acoustic waves transmitted from the transmitting means in the X-axis and Y-axis directions include first reflection arrays (first reflecting means; 4a, 4b) formed at both edge portions in the Y-axis direction and second edge portions formed at both edge portions in the X-axis direction. The direction is redirected by reflecting means consisting of reflecting arrays (second reflecting means; 5a, 5b), and propagates over the entire surface (active area) of the display area 2 in the X-axis and Y-axis directions, The acoustic wave is instructed again, that is, converges in the X-axis and Y-axis directions so as to be received by the receiving means.

The receiving means 6a, 6b are comprised with the same member as a transmitting means. The transmitting means and the receiving means are mainly distinguished by a coupling method for electronics. For example, if items 6a and 6b are connected to excitation circuit elements and 3a and 3b are connected to receiving circuit elements, 6a and 6b function as transmission means and 3a and 3b as reception means.

The signal cables 7a and 7b are connected to the transmitting element, and the signal cables 8a and 8b are connected to the receiving element.

In such an apparatus, when an excitation signal such as 20 to 30 cycles of a beep burst or the like is intermittently sent to the transmitting means 3a (or 3b) via the cable 7a (or 7b), the ultrasonic waves are reflected array 4a or Reflected by (5a), propagated through the surface of the glass substrate 1, reflected by the reflective array 4b or 5b, and received by the receiving means 6a or 6b. Since the delay of the acoustic waves is less than 1 ms in total, the X and Y coordinate measuring subsystems can be excited in turn within the response time of the person. The received signal is sent to the signal processing control device via the signal cable 8a (or 8b), whereby the control device recognizes the received signal and detects its strength.

The touch panel shown in FIG. 1 is, for example, a computer peripheral device of a main computer that controls an output device such as a display device and a sound system, and is placed in front of the display device. Here, according to the application software of the host computer, the result of the detected touch can be fed back to the user (person). The feedback may be, for example, highlighting of an icon in a display image, a sound (click sound, a ringtone, etc.), an operation on a touch control function, or the like. All of these operations rely on an acoustic touch panel system that accurately detects touch, the exact detection of which depends on maintaining a sufficient SN ratio.

Acoustic waves lose intensity when propagated through the glass substrate of the touch panel. The physical effect, that is, the attenuation of acoustic wave energy by the substrate is an important factor in determining the signal amplitude of the acoustic touch panel. In the touch panel according to the present invention, since a predetermined glass substrate is used, the attenuation of the ultrasonic waves is reduced and a received signal having a sufficient intensity is detected. As a result, the touch position is detected with good reliability and with high accuracy.

In the touch panel assembled using the glass of the present invention, the signal amplitude is significantly increased. The glass having low acoustic wave loss according to the present invention is easily and economically commercially available since it is in the form of a sheet, and may be optionally heat or chemically strengthened or cured. Since the signal amplitude increases when such a glass substrate is used, the SN ratio can usually be improved even if the product has a significant decrease in the SN ratio. Therefore, for example, it can use advantageously also in the following cases.

When designing transducers, for example members 3a, 3b and 6a, 6b, designers often have to tolerate a reduction in signal amplitude in order to mount the touch panel into the display housing. For example, designers often reduce the width of transducers, for example from 0.5 inches to 0.25 inches, to overcome mechanical limitations. In addition, the designer may sometimes intersect the wedge transducer and the touch surface at a sharp inclination angle. However, this design causes signal loss. In such a case, using a substrate with low acoustic wave loss enables the designer to lower the efficiency of the transducer, thereby enabling a mechanically suitable touch panel.

In addition, as shown in FIG. 4, when the sealing material is to be provided between the touch surface and the housing of the display device, the sealing material absorbs acoustic waves, so the designer selects which of the mechanical design and the signal amplitude should be prioritized. There is a case to be done. In FIG. 4, the touch panel 100 and the CRT 102 are mounted to the housing 104 and the touch panel 100 is held in a suitable place by the adhesive tape 106. Since the sealing material 108 is in contact with the surface of the touch panel 100, acoustic wave energy is absorbed. However, when using the touch panel of the present invention, the signal supply is increased, which may cause acoustic wave energy loss.

The designer has to make another choice when designing the electronics. Current control products used in conjunction with acoustic touch panels generate dozens of peak-to-peak volts excitation signals. Due to the large excitation voltage, electronic circuits are expensive and may emit unacceptable levels of EMI. If the excitation voltage can be reduced by, for example, 15 dB, there are many advantages, but as the excitation voltage is lowered, the received signal is also lost by 15 dB. By using the glass substrate of the present invention, a sufficient signal is provided to enable such a drop in the excitation voltage.

The most effective product improvement using a glass substrate with low acoustic wave loss is that the size of the sensor can be greatly increased. Recently, Elo Touch Systems Inc. has introduced acoustic wave touch panel products, which are large touch panels with a diagonal length of 21 inches.

Elo originally planned a 21-inch soda-lime glass product, but it could not guarantee reliable quality performance due to its low signal amplitude. It can be seen from the following calculation that the signal amplitude is greatly reduced when the size of the soda-lime glass touch panel is slightly increased. Assuming that the aspect ratio of a standard video display is 3: 4, increasing the diagonal length by 1 inch, the maximum path length of the acoustic wave (maximum path length of the acoustic wave = integer + X array length) 2 times + internal spacing between X arrays) is increased by 2.2 inches. If the attenuation is 1.5 dB / inch, the diagonal increases by 1 inch, the absorption in the substrate is increased by 3.3 dB. When the diagonal is increased by 3 inches, the signal is degraded by 10 dB. Therefore, it becomes very difficult to manufacture a larger acoustic wave touch panel made of soda lime glass. As ELO Touch Systems proved through a 31-inch diagonal touchpanel, which had a laminated reverse projection screen at the Comdex exhibition in Las Vegas in November 1996 and was examined and functioned by a projection display, A much larger size can be obtained when using the glass substrate of the present invention. The conceptual diagram of the touch panel shown in FIG. 5 illustrates the use of a large touch panel in constructing a projection image. The projector 118 and the lens 120 project a real-time video image onto the reverse projection screen 110. The screen may be stacked inside the substrate of the acoustic touch panel 122. That is, the glass substrate of the acoustic touch panel can be laminated to the back-projection screen material. Reference numeral 112 is a housing, 114 is a sealing material.

There is increasing interest in the market for very large touch panels that can be used for audio visual (AV) applications. In the case of using large pieces of glass for applications requiring frequent contact, safety and strength need to be fully considered. As the niche of these emerging markets matures, there is a possibility that a reinforcement plate of a very large acoustic touch panel is required.

The glass constituting the substrate according to the invention can be thermally or chemically strengthened by conventional methods. For example, the glass may be heated to red, then rapidly cooled on both sides and compressed strongly to be thermally cured, for example, to 15,000 psi overall or partially up to 10000 psi. Here, the interior of the glass is cooled slowly, as a result of which it is put under tension and pulled parallel to them by both surfaces. The glass can be strengthened by heat only when the coefficient of thermal expansion is sufficiently large, that is, the coefficient of thermal expansion before strengthening is about 6 × 10 ⁻⁶ / K or more.

The coefficient of thermal expansion of the glass used in the present invention is usually about 6 × 10 ⁻⁶ / K or more, preferably about 6 × 10 ⁻⁶ / K to about 12 × 10 ⁻⁶ / K, more preferably, before strengthening. Preferably about 7 × 10 ⁻⁶ / K to about 10 × 10 ⁻⁶ / K, in particular about 8 × 10 ⁻⁶ / K to about 10 × 10 ⁻⁶ / K. For example, the thermal expansion coefficient of said "CS25" is 8.3x10 <^-6> / K (20 degreeC-300 degreeC). This value is similar to that of soda-lime glass (coefficient of thermal expansion = 8.5 to 9 × 10 ⁻⁶ / K), and borosilicate glass such as “boron float”, which cannot be thermally strengthened (coefficient of thermal expansion = about 3 × 10 ⁻⁶ / K) Is very different.

In addition, the glass used in the present invention may be chemically strengthened (cured) by, for example, the method disclosed in US Pat. No. 3954487. Chemical curing can be accomplished by substituting slightly higher alkali metal ions, depending on the glass surface, with higher alkali metal ions, for example lithium and / or sodium ions, replaced by potassium ions.

As such, the borosilicate glass cannot be strengthened, but the glass used in the present invention can be strengthened and has a low acoustic wave loss. That is, in a touch panel composed of a substrate through which acoustic waves can propagate and means for introducing the acoustic waves into the substrate, the substrate has attenuation coefficient of about 0.25 dB / cm or less and is chemically or thermally strengthened. Although it is formed of glass which can be made, the glass substrate is often strengthened by heat. A "substantially" tempered glass, for example, increases in strength by about 50 or more, preferably about 100 or more. In the case of using such glass, the size of the acoustic wave touch panel can be increased.

In using the strengthened glass substrate, it is necessary to use a curing process that does not anneal the reflective array material and the glass, for example, a low temperature curing reflective material of a polymer substrate can be used. Since the polymer material attenuates the acoustic wave power more rapidly than the glass raw material which is a more conventional reflective material, the necessity of the board | substrate with less acoustic wave loss increases.

As the reflective array material, a glass raw material such as "ESL4022C" having a coefficient of thermal expansion of 8.8 x 10 ^-6 / K or a reflective ink that can be cured at a temperature lower than the annealing temperature of the glass can be used. Since the "ESL4022C" glass raw material whose thermal expansion coefficient is 8.8x10 <^-6> / K has a value comparable to the typical thermal expansion coefficient of soda-lime glass, it is utilized widely. For example, the soda-lime glass of the brand name "Star Fire" has a coefficient of thermal expansion of 9.0 × 10 ⁻⁶ / K.

A glass substrate can also be used as safe glass comprised from the some glass layer. For example, as shown in FIG. 6, when the glass substrate is formed of a laminate in which the outer layer glass 152 having the inner layer glass 151 and the touch surface 152a is laminated through the adhesive 153, The touch panel can be configured. The attenuation coefficient of 25 dB / cm or less can be provided to an outer layer using the low acoustic wave loss glass of this invention. Since safety glass (laminated glass) has high strength, it is not necessary to strengthen the glass, but as long as the upper layer (layer forming the touch surface) is made of glass with a low damping coefficient, either or both inner and outer glass may be used. All may be thermally or chemically strengthened, and at least it is advantageous to strengthen the innerlayer glass. For example, in the safety glass laminated up and down, although the glass of both upper and lower sides may be strengthened, when only the glass of lower surface is strengthened, a safety glass can be strengthened effectively. When a load or an impact acts on the upper surface of the glass substrate which is the touch surface, the safety glass is bent to compress the glass layer on the upper surface and the glass layer on the lower surface is pulled out, while the glass is strong in the compressed state, but very weak under tension. For this reason, when glass of an inner layer (lower layer) is comprised by tempered glass, destruction of an upper layer can be prevented. As the glass of the inner layer (lower layer), glass that can be strengthened may be used, and glass containing barium or high attenuation coefficient (for example, inexpensive and high transparency soda lime glass) may be used. In addition, you may use the glass of the heat strengthening acoustic wave loss of this invention for glass of an inner layer (lower layer) as needed. It is a preferred embodiment to form a glass substrate with an upper layer composed of glass having an attenuation coefficient of 0.25 dB / cm or less and a lower layer composed of tempered soda lime glass.

In terms of coefficient of expansion, the inner and outer layers of the laminate are typically approximate or substantially the same. If the coefficients of thermal expansion of the glass of the outer layer and the inner layer are different from each other, the glass substrate may be bent back and bend due to the temperature change. The thermal expansion coefficient of the glass with less acoustic wave loss of the present invention is approximately the same as that of soda-lime glass or glass containing barium. Therefore, when using soda-lime glass or glass containing barium (especially tempered glass) in the inner layer and glass having low acoustic wave loss of the present invention in the outer layer, high-strength laminated glass with little change in shape even when the temperature is changed. Can be obtained. In addition, when the soda-lime glass is used for the inner layer and the borosilicate glass is used for the outer layer, the coefficient of thermal expansion is greatly different, so that the glass substrate is surely bent and bent as the temperature changes.

In addition, the thermal expansion coefficient of glass with low acoustic wave loss is very suitable for the conventional glass raw material used as a reflective array material of commercially available touch panel products, so that the reflective array can be integrated with the glass substrate when the sintering temperature is low. . On the other hand, since the thermal expansion coefficient of borosilicate glass is not suitable for a normal glass raw material, the joining degree of borosilicate glass and a glass raw material is small, and requires high sintering temperature.

In the case of using the acoustic wave panel and the glass substrate therefor according to the present invention thus obtained, since the glass having low loss is used, the SN ratio is increased and the signal is increased. This gives you the following advantages:

(1) Since the SN ratio is increased, the cost of the electronic control apparatus related to the touch panel can be reduced.

(2) The overall size of the touch panel can be increased by preventing the loss due to the scattering of acoustic waves in the long acoustic wave path and increasing the SN ratio. For example, a rectangular touch panel with a diagonal length of 21 inches or more can be obtained.

(3) Since SN ratio is high, the sealing material which absorbs acoustic wave energy can be used together. That is, the sensitive part of the touch panel and the adjacent object can be contacted (sealed, etc.).

(4) Because signal loss caused by attenuation in substrate material is reduced, designers can prioritize design and sacrifice signal amplitude. For example, when a touch panel is mounted in a touch / display system, the mechanical design can be optimized at the expense of the amplitude of the acoustic wave signal.

Moreover, when used as laminated glass, it is reliable even when handled roughly and its touch surface is solid. In addition, the thermally or chemically strengthened to enable a large reinforced touch panel.

In the present invention, the glass substrate includes not only various acoustic waves, such as Rayleigh waves, but also horizontally polarized shear waves, higher order horizontally polarized shear waves, and zero-order horizontal polarization. It is suitable for propagating zeroth order horizontally polarized shear waves, or love waves. Since the love wave shares the same damping mechanism as the Rayleigh wave, the glass according to the invention has a reduced attenuation compared to soda lime glass for all acoustic wave modes. Rayleigh waves are preferable as the acoustic wave mode.

As described in US Pat. No. 5591945, Rayleigh waves propagate along the reflective array, and the active area (or active area) of a sensor (hereinafter referred to as Rayleigh-shear-Rayleigh sensor). ), An acoustic touch panel can be designed in which horizontal polarization transverse waves sense a touch. Such a sensor can sense a touch even if it is sealed with silicone rubber (RTV) and can sense a touch even if the active area is covered with water.

Using low acoustic wave loss glass, a large Rayleigh-cross-Raily sensor can be manufactured.

If the operating frequency is 5.53 MHz, the glass thickness is limited to about 3 mm, according to the wave dynamics of the Rayleigh-cross-railley sensor. In addition, since the Rayleigh-lateral-Railey sensor has touch sensitivity on both the top and bottom surfaces of the glass, it cannot be laminated as part of the safety glass substrate using a standard safety glass adhesive (silicon with little attenuation of viscosity). Adhesives such as rubber). With this wave dynamic requirement of Rayleigh-cross-leyley touch panels, the tempered glass with less acoustic wave loss of the present invention becomes more interesting due to the large Rayleigh-cross-leyley touch panels.

Hereinafter, the present invention will be described in more detail based on Examples, and the present invention is not limited to the Examples described below.

Comparative Example 1

Using a flat soda-lime glass substrate (Central Glass Company: 488 mm (width) x 403 mm (length) x 3.3 mm (thickness)), an acoustic wave touch panel shown in FIG. 3 was manufactured. Rayleigh waves were excited and propagated in the acoustic wave touch panel, and the performance of the touch panel was observed using a control device (5810EI00, manufactured by Touch Panel Systems Co., Ltd.). Soda-lime glass contains SiO ₂ (71 wt.%), Na ₂ O (13 wt.%), K ₂ O (1 wt.%), CaO (11 wt.%), MgO (2 wt.%), Al ₂ O ₃ (2 Wt%), B ₂ O ₃ (0 wt%), SrO (0 wt%), ZrO ₂ (0 wt%), BaO (0 wt%), the sum of the contents of Na ₂ O, CaO and MgO Was 26% by weight.

The light transmittance of the glass substrate in visible region is 91% (made by Suga Test Instruments Co., Ltd., using Haze Computer HGM-2D). Absolute calibration of these measurements is slightly inaccurate, but it is helpful enough in comparison with other glasses (92% is theoretically the upper limit of transmission, as it shows 4% reflectivity on both the front and face of the glass). Reflection is caused by an inadequate refractive index between air and glass, which is typically about n = 1.5, so that reflection on a single surface (n-1 / n + 1) ² is about 4%). .

Moreover, it was 0.57 dB / cm when the attenuation coefficient was measured by the said method.

The propagation speed of the acoustic wave was measured by the method described below.

The propagation speed of the acoustic wave was obtained by observing when the amplitude of the received signal was the largest by changing the pitch or distance between the elements of the reflective array. The pitch and spacing are the strongest when they correspond to integer multiples of the wavelength of sound corresponding to a fixed operating frequency. A series of samples were prepared to change the pitch of the reflective array little by little. The wavelength was obtained from the pitch giving the maximum reception amplitude, and the speed was calculated by multiplying the wavelength by the frequency (5.53MHz).

As in the case of commercially available Rayleigh wave touch panel products, an acoustic wave signal was transmitted to and received from a glass surface provided with a wedge transducer. The wedge transducer is composed of a ceramic piezoelectric element bonded to a plastic wedge, and the wedge is bonded to a glass surface. The wedge couples (couples) an acoustic wave in a pressure mode from the piezoelectric element to a Rayleigh wave on a glass substrate. Transmitter is 5.53MHz of 50V amplitude Was here by Tonburst.

As a result of the measurement, the propagation speed of the soda-lime glass substrate was 125000 inches / sec.

For a touch panel designed with a propagation speed of 125000 inches / sec, the strength of the received signal was measured by the receive transducer. Measurements were made for both the X- and Y-axis subsystems of the touch panel and the measured intensities were 1.41 mV and 1.69 mV, respectively.

Comparative Example 2

Instead of the soda glass of the comparative example 1, the flat borosilicate glass substrate (the shot company make, brand name "Tenfax"; 488 mm (width) x 403 mm (length) x 3.3 mm (thickness)) was used. The glass substrate is SiO ₂ (81% by weight), Na ₂ O (3% by weight), K ₂ O (1% by weight), B ₂ O ₃ (13% by weight) and Al ₂ O ₃ (2% by weight) It consisted of, the total content of Na ₂ O, CaO and MgO was 3% by weight.

As a result of measuring through the method of Comparative Example 1, the light transmittance of the glass substrate in the visible light region was 93.0.

In addition, as a result of the measurement by the above method, the attenuation coefficient was 0.30 dB / cm, the propagation speed was 122288 inches / second.

For a touch panel designed to have a propagation speed of 122288 inches / sec, the intensity of the received signal was measured on both the X-axis and the Y-axis using the method of Comparative Example 1. The intensity on the X axis (horizontal axis in FIG. 1) was 6.66 mV, and the intensity on the Y axis (vertical axis in FIG. 1) was 8.39 mV.

The thermal expansion coefficients of "Tenfax" and "Boron Float" are about 3.3x10 <^-6> / K, and thermal strengthening and chemical strengthening are impossible.

Reference Example 1

A glass substrate that is flat in place of the soda-lime glass used in Comparative Example 1 (produced by Shot Co., Ltd., trade name "B270" or Desag Co., Ltd., "Super Wight"; 488 mm (width) x 403 mm (length) x 3.3 mm (thickness)) Was used. The glass substrate is SiO ₂ (69 wt%), Na ₂ O (8 wt%), K ₂ O (8 wt%), CaO (7 wt%), BaO (2 wt%), ZnO (4 wt% ), TiO ₂ (1 wt%), Sb ₂ O ₃ (1 wt%), B ₂ O ₃ (2 wt%), Al ₂ O ₃ (0 wt%), SrO (0 wt%), ZrO ₂ ( 0% by weight), and the total content of NaO ₂ , CaO and MgO was 15% by weight.

As a result of measuring through the method of Comparative Example 1, the light transmittance of the glass substrate in the visible light region was 92.8.

As a result of the measurement by the above method, the attenuation coefficient was 0.24 dB / cm and the propagation speed had a Rayleigh wave propagation speed of 121609 inches / sec.

The intensity of the received signal was measured with respect to the X-axis and the Y-axis of the touch panel having a Rayleigh wave propagation speed of 121609 inches / sec by the method described in Comparative Example 1. The strength of the received signal was 7.69 mV on the X axis and 7.50 mV on the Y axis.

The thermal expansion coefficient of the said glass was about 9.5x10 <^-6> / K, and the softening point (10 ^7.6 poise) of "B270" glass was 708 degreeC.

Reference Example 2

A glass substrate (Asahi Glass Co., Ltd. make, brand name "PD-200") was used instead of the glass of the reference example 1. The glass substrate is SiO ₂ (60% by weight), Na ₂ O (3% by weight), K ₂ O (7% by weight), CaO (3% by weight), BaO (7% by weight), B ₂ O ₃ ( 0 wt%), Al ₂ O ₃ (8 wt%), SrO (6.3 wt%), ZrO ₂ (2.7 wt%), and the total content of Na ₂ O, CaO and MgO was 8 wt%.

As measured by the method described in Comparative Example 1, the light transmittance of the glass substrate in the visible region was 91.1%, the attenuation coefficient was 0.21 dB / cm, and the propagation speed had a Rayleigh wave propagation speed of 118,518 inches / sec.

The intensity of the received signal was measured on the X and Y axes of the touch panel having a Rayleigh wave propagation speed of 118,518 inches / sec by the method of Comparative Example 1, and it was 15 mV on the X axis and 17 mV on the Y axis.

The thermal expansion coefficient of this glass was about 8.3x10 <^-6> / K, and the softening point (10 ^7.6 poise) was 830 degreeC.

Example 1

Instead of the glass of Reference Example 1, a glass substrate (manufactured by Saint-gobain) and a brand name "CS25" was used. The glass substrate is SiO ₂ (59% by weight), Na ₂ O (5% by weight), K ₂ O (9% by weight), CaO (6% by weight), BaO (0.2% by weight), B ₂ O ₃ ( 0 wt%), Al ₂ O ₃ (4 wt%), SrO (8 wt%), ZrO ₂ (7.5 wt%) and the total content of Na ₂ O, CaO and MgO was 12 wt%.

As measured by the method described in Comparative Example 1, the light transmittance of the glass substrate in the visible region was 89.5%, about the same as that of soda lime glass, the attenuation coefficient was 0.18 dB / cm, and the propagation speed was about the same as that of the soda lime glass. It had a Rayleigh wave propagation rate of 124,700 inches / sec.

The intensity of the received signal was measured on the X and Y axes of a touch panel with a Rayleigh wave propagation speed of 124,700 inches / sec by the method described in Comparative Example 1, which was 35 mV on the X axis and 40 mV on the Y axis. Received strength is greater than that of lime glass or borosilicate glass.

Touch was detected using a touch panel connected to the control device. By clearly falling the received signal, the touch position could be accurately determined. That is, in order to detect the coordinate of a touch position, a touch panel was connected to the control apparatus. As shown in Fig. 2, when the panel touches the panel, the received signal shows a significant drop Dt in the intensity D of the received signal, and as a result, the touch position can be clearly recognized. This gives you the desired touch panel functionality.

The thermal expansion coefficient of the said glass is about 8.3x10 <^-6> / K, and it is glass which can be thermally strengthened and chemical hardening. In addition, the softening point (10 ^7.6 poise) is 843 degreeC.

The results of Examples, Comparative Examples and Reference Examples are shown in a table.

Transmittance Attenuation rate Propagation speed Thermal expansion Softening point density Comparative Example 1 91 0.57 125,000 8.5-9.0 720-735 2.49 Comparative Example 2 92 0.30 122,288 3.3 820 2.3 Reference Example 1 92 0.24 120,000 9.5 708 2.56 Reference Example 2 91 0.21 118,518 8.3 830 2.77 Example 1 90 0.18 124,700 8.3 843 2.77

In the above embodiment, the touch panel substrate of the embodiment can more effectively prevent the acoustic wave attenuation and increase the SN ratio as compared with the touch panel substrate of the comparative example. Furthermore, it can be thermally or chemically strengthened.

According to the acoustic wave touch panel of the present invention, the acoustic wave attenuation of the glass substrate can be reduced, and the strength of the signal can be improved. Therefore, an acoustic wave touch panel with high reliability and high durability with respect to electromagnetic interference can be obtained. Moreover, an acoustic wave type touch panel can be used even if the converter which has low signal efficiency conversion is used, or even if the sealing material which acoustic wave absorption generate | occur | produces is used. Moreover, it can be thermally or chemically strengthened to produce a large, reinforced touch panel.                     

Claims (15)

It functions as a transmission medium for acoustic waves composed of SiO ₂ as a main component, Al ₂ O _{3 in a} content of 2.5 to 20% by weight, ZrO _{2 in a} content of 3 to 20% by weight and SrO in a content of 6.5 to 20% by weight. A touch panel having a glass substrate and for detecting coordinate data regarding a contact position, wherein the glass substrate has a thickness sufficient to support the propagation of the Rayleigh wave from the substrate surface to a Ray-Leigh wave of 5.53 MHz. When a pair of wedge transducers with a width of 0.5 inches are mounted so as to face the glass sample to be tested, and the measurement is made through the slope of the amplitude versus distance plot with respect to the signal, the attenuation coefficient is about 0.25 dB / cm or less. , (1) has a propagation rate substantially the same as that of soda-lime glass, (2) A touch panel having at least one of the properties described in (1) and (2) above, wherein the additional component further comprises 0 to 1.5% by weight of BaO or 0 to 4% by weight of B ₂ O ₃ . delete The touch panel of claim 1, wherein the additional component comprises any one of BaO and B ₂ O ₃ , wherein the attenuation coefficient of the glass substrate is about 0.20 dB / cm or less. A touch panel having a glass substrate functioning as a transmission medium for acoustic waves, and for detecting coordinate data relating to a contact position, wherein the glass substrate is composed of SiO _{2 as a} main component and an additional component, wherein the additional component is (A) 0 to 1.5 weight percent BaO, 3 to 20 weight percent ZrO ₂ and 6.5 to 20 weight percent SrO components, (B) 0 to 1.5% by weight of BaO or 0 to 4% by weight of B ₂ O ₃ , 2.5 to 20% by weight of Al ₂ O ₃ , 3 to 20% by weight of ZrO ₂ and 6.5 to 20 At least one component selected from weight percent SrO, (C) is, of the (A) comprises a ZrO ₂ and Al ₂ O _3, and the ratio of Al ₂ O ₃ and ZrO ₂ ZrO ₂ / (Al ₂ O ₃ + ZrO ₂₎ = 30 to 100% by weight to Touch panel having at least one characteristic selected in (C). delete The touch panel of claim 4, wherein the total content of Al ₂ O ₃ and ZrO ₂ is 3 to 20 wt%. The method of claim 4, wherein the ratio of Al ₂ O ₃ and ZrO ₂ is ZrO ₂ / (Al ₂ O ₃ + ZrO ₂ ) = 40 to 90% by weight, and the total content of Al ₂ O ₃ and ZrO ₂ is 8 to 20 wt% touch panel. The touch panel of claim 4, wherein the glass substrate further comprises K ₂ O in an amount of 5 to 10 wt%. The touch panel of claim 4, wherein the total content of Na ₂ O, CaO, and MgO in the glass substrate is 7-20 wt%. 5. A touch panel according to claim 1 or 4, comprising a substrate through which acoustic waves can propagate and means for introducing the acoustic waves into the substrate, wherein the substrate is formed of glass which can be chemically or thermally strengthened. Touch panel. The touch panel according to claim 1 or 4, wherein the glass substrate is strengthened by heat, and the coefficient of thermal expansion before strengthening is about 6 × 10 ⁻⁶ / K to about 12 × 10 ⁻⁶ / K. The touch panel according to claim 1 or 4, wherein the glass substrate has a density of 2.6 to 3.0 g / cm 3. The touch panel according to claim 1 or 4, wherein the softening point of the glass substrate is 800 to 900 ° C. The touch panel according to claim 1 or 4, wherein the acoustic wave is a Rayleigh wave, a horizontal polarized wave, a higher-order horizontal polarized wave, a zero-order horizontal polarized wave, or a love wave. The glass substrate which comprises the acoustic wave type touch panel for detecting the coordinate data regarding a contact position, The glass substrate of Claim 1 or 4.

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