JP7709330B2 - Display device and electronic device - Google Patents

Description

The present invention relates to a display device and electronic device capable of presenting a tactile sensation.

Some smartphones and car navigation systems are equipped with a force feedback function that vibrates when the touch panel is operated, notifying users that their input has been accepted. In recent years, haptic technology has been developed that goes beyond vibrations for notifications, and can provide a variety of vibrations to express the feel of displayed objects and identify the operating position.

This type of tactile technology can be achieved by vibrating a piezoelectric actuator attached to a tactile panel at an ultrasonic frequency. The ultrasonic vibration creates standing waves in the tactile panel, and when the tactile panel is touched with a finger or the like, a tactile sensation can be sensed. By changing the signal pattern supplied to the piezoelectric actuator, a wide variety of tactile sensations can be expressed.

Here, when the vibrating surface of the tactile panel is touched with a finger or the like, contact noise may be generated. In response to this, Patent Document 1 discloses a touch panel display that reduces contact noise by increasing the surface roughness of the tactile panel surface.

JP 2019-16111 A

However, as described in Patent Document 1, although it is possible to reduce contact noise by increasing the surface roughness of the tactile panel, the tactile sensation caused by the vibration of the tactile panel is reduced. Furthermore, when a finger is moved while the tactile panel is not vibrating, friction noise is generated due to friction between the tactile panel and the finger, etc.

In view of the above circumstances, the object of the present invention is to provide a display device and electronic device that suppresses contact noise and friction noise and provides an excellent tactile sensation due to ultrasonic vibrations.

In order to achieve the above object, a display device according to one embodiment of the present invention includes a tactile panel and a piezoelectric actuator.
The tactile panel has a first major surface and a second major surface opposite the first major surface.
The piezoelectric actuator is disposed on the second main surface and generates vibrations.
The first main surface has a roughened region having a surface roughness Rz of a first surface roughness, and a non-roughened region having a second surface roughness Rz of 0.001 to 0.8 times the first surface roughness, and an area ratio of the roughened region on the first main surface is 30% to 90%.

The first surface roughness may be greater than or equal to 3 μm and less than or equal to 20 μm.

The second surface roughness may be 0.003 μm or more and 16 μm or less.

The second surface roughness may be 0.05 μm or more and 10 μm or less.

The roughened and non-roughened regions may be arranged alternately in a first direction parallel to the first main surface and a second direction parallel to the first main surface and perpendicular to the first direction.

The tactile panel may be made of resin or glass.

In order to achieve the above object, an electronic device according to one aspect of the present invention includes a tactile panel and a piezoelectric actuator.
The tactile panel has a first major surface and a second major surface opposite the first major surface.
The piezoelectric actuator is disposed on the second main surface and generates vibrations.
The first main surface has a roughened region having a surface roughness Rz of a first surface roughness, and a non-roughened region having a second surface roughness Rz of 0.001 to 0.8 times the first surface roughness, and an area ratio of the roughened region on the first main surface is 30% to 90%.

As described above, the present invention makes it possible to provide a display device and electronic device that suppresses contact noise and friction noise and provides an excellent tactile sensation due to ultrasonic vibrations.

1 is a side view of a display device according to an embodiment of the present invention. FIG. 2 is a plan view of the front surface side of the display device. FIG. 2 is a plan view of the rear surface side of the display device. FIG. 2 is a cross-sectional view of the display device. 4 is a cross-sectional view of a piezoelectric actuator included in the display device. FIG. 5A to 5C are schematic diagrams illustrating the operation of the display device. 3 is a schematic diagram showing a roughened area and a non-roughened area on a first main surface of a tactile panel provided in the display device. FIG. 3 is a schematic diagram showing a checkered pattern of the rough surface area and the non-rough surface area. FIG. 3 is a schematic diagram showing a lattice pattern of the rough surface region and the non-rough surface region. FIG. 3 is a schematic diagram showing circular patterns of the roughened and non-roughened regions. FIG. FIG. 2 is a schematic diagram showing a composite pattern of the rough surface area and the non-rough surface area. 1 is a graph showing a relationship between a first surface roughness and a contact noise. 1 is a graph showing a relationship between a first surface roughness and friction noise. 1 is a graph showing a relationship between a first surface roughness and a tactile sensation. 10 is a graph showing the relationship between the area ratio of the rough surface region and contact noise. 1 is a graph showing the relationship between the area ratio of the rough surface region and fricative noise. 1 is a graph showing the relationship between the area ratio of the rough surface region and the tactile sensation. 11 is a graph showing sound pressure characteristics of a display device according to a comparative example. 4 is a graph showing sound pressure characteristics of the display device according to the present invention.

The display device according to this embodiment is described below.

[Configuration of the display device]
Fig. 1 is a side view of a display device 100 according to an embodiment of the present invention. Fig. 2 is a plan view of the display device 100 as viewed from the front side, and Fig. 3 is a plan view of the display device 100 as viewed from the back side. Fig. 4 is a cross-sectional view of the display device 100, taken along line A-A in Figs. 2 and 3.

As shown in these figures, the display device 100 comprises a display panel 101, a touch panel 102, a tactile panel 103, and a piezoelectric actuator 104. As shown in Figures 2 and 3, the display device 100 is flat and has a rectangular shape when viewed in a direction perpendicular to the thickness direction. In each figure of this disclosure, the longitudinal direction of the display device 100 is the X direction, the lateral direction is the Y direction, and the thickness direction is the Z direction.

The display panel 101 is a panel that displays images, and is a display panel that uses liquid crystal or organic EL (electro-luminescence), etc. The configuration of the display panel 101 is not particularly limited, and it can be a display having a general configuration.

The touch panel 102 is disposed on the display panel 101, and detects touches on the display device 100 by a user's finger or the like. The touch panel 102 has an array of touch sensors, and the touch sensors are preferably of the capacitive type. The touch panel 102 may be a laminate of a touch panel body and a protective cover glass, or may be an integrated body of the touch panel body and the protective cover glass.

The tactile panel 103 is disposed on the touch panel 102 and presents a tactile sensation to the user. As shown in FIG. 1, the tactile panel 103 has a longer side than other members such as the touch panel 102, and has a portion 103a that protrudes from the other members. A piezoelectric actuator 104 is joined to this portion 103a, and vibrations are generated by the piezoelectric actuator 104. The tactile panel 103 is made of a light-transmitting material such as glass or resin. As shown in FIG. 4, the main surface of the tactile panel 103 opposite the touch panel 102 is the first main surface 103b, and the main surface on the touch panel 102 side opposite the first main surface 103b is the second main surface 103c. The first main surface 103b has a rough surface area and a non-rough surface area. These areas will be described later.

The piezoelectric actuator 104 is bonded to the tactile panel 103 and generates vibrations. As shown in FIG. 1, the piezoelectric actuator 104 is bonded to the second main surface 103c of the tactile panel 103 at the portion 103a. FIG. 5 is a cross-sectional view of the piezoelectric actuator 104. As shown in the figure, the piezoelectric actuator 104 includes a piezoelectric body 121, a first electrode 122, and a second electrode 123. The piezoelectric body 121 is made of a piezoelectric material such as PZT (lead zirconate titanate).

The first electrode 122 includes a first internal electrode 124 and a first external electrode 125. The first internal electrode 124 is made of a conductive material and is provided in multiple layers in the piezoelectric body 121. The first external electrode 125 is made of a conductive material and is connected to the first internal electrode 124. The second electrode 123 includes a second internal electrode 126 and a second external electrode 127. The second internal electrode 126 is made of a conductive material and is provided in multiple layers in the piezoelectric body 121. The second external electrode 127 is made of a conductive material and is connected to the second internal electrode 126.

As shown in FIG. 5, the first internal electrodes 124 and the second internal electrodes 126 are arranged alternately and face each other via the piezoelectric body 121. The number of layers of the first internal electrodes 124 and the second internal electrodes 126 is not limited to three each. As shown in FIG. 2 and FIG. 3, the first wiring 128 is connected to the first electrode 122, and the second wiring 129 is connected to the second electrode 123. The first wiring 128 and the second wiring 129 are connected to a drive unit (not shown) and transmit a drive signal output from the drive unit to the first electrode 122 and the second electrode 123.

When a voltage is applied between the first electrode 122 and the second electrode 123 by this drive signal, the piezoelectric body 121 deforms due to the inverse piezoelectric effect, generating vibration. Here, in the display device 100, the control unit can supply an ultrasonic drive signal to the piezoelectric actuator 104 to cause the piezoelectric actuator 104 to vibrate in the ultrasonic band (20 kHz or higher). Note that the piezoelectric actuator 104 may have a layered structure in which the first electrode 122 and the second electrode 123 are alternately layered with the piezoelectric body 121 interposed therebetween, as shown in FIG. 5, or may have another structure.

The display device 100 has the above-described configuration. The display device 100 can be mounted on electronic devices such as smartphones.

[Operation of the display device]
The operation of the display device 100 will now be described. Fig. 6 is a schematic diagram showing the operation of the display device 100. As shown in the figure, when a user vibrates the piezoelectric actuator 104 (see Fig. 1) in the ultrasonic band while the user has his/her finger F in contact with the first main surface 103b of the tactile panel 103, the vibration is transmitted to the tactile panel 103, causing the tactile panel 103 to vibrate. This allows the finger F to sense touch.

The contact of the finger F with the tactile panel 103 is detected by the touch panel 102. Furthermore, the image displayed by the display panel 101 is visible through the touch panel 102 and the tactile panel 103.

[Regarding the first principal surface]
As described above, a rough surface area and a non-rough surface area are formed on the first main surface 103b of the tactile panel 103. Fig. 7 is a plan view of the first main surface 103b, and Fig. 8 is an enlarged view of Fig. 7. As shown in Figs. 7 and 8, a rough surface area 131 and a non-rough surface area 132 are formed on the first main surface 103b.

The rough surface region 131 is a roughened region, and the surface roughness Rz of the rough surface region 131 is referred to as the "first surface roughness Rz1." The non-rough surface region 132 is a non-roughened region, and the surface roughness Rz of the non-rough surface region 132 is referred to as the "second surface roughness Rz2." Note that the surface roughness Rz refers to the ten-point average roughness (defined by JIS B 0601:2001 (compliant with ISO4287-1997)).

The first surface roughness Rz1 and the second surface roughness Rz2 are preferably such that the second surface roughness Rz2 is 0.001 to 0.8 times the first surface roughness Rz1. Specifically, the first surface roughness Rz1 is preferably 3 μm to 20 μm, and the second surface roughness Rz2 is preferably 0.003 μm to 16 μm. Furthermore, the second surface roughness Rz2 is more preferably 0.05 μm to 10 μm.

As shown in Figures 7 and 8, the rough surface area 131 and the non-rough surface area 132 form a pattern and are arranged alternately in a first direction (X direction in the figure) parallel to the first main surface 103b and a second direction (Y direction in the figure) parallel to the first main surface 103b and perpendicular to the first direction. As shown in Figures 7 and 8, the pattern can be a checkered pattern. As shown in Figure 7, the pattern is formed on the entire first main surface 103b. The pattern may also be formed only on a major portion of the first main surface 103b. The pattern of the rough surface area 131 and the non-rough surface area 132 is not limited to a checkered pattern, and may be any pattern in which the rough surface area 131 and the non-rough surface area 132 are arranged alternately in the first direction (X direction in the figure) and the second direction (Y direction in the figure).

9 to 11 are schematic diagrams showing other patterns of the rough surface area 131 and the non-rough surface area 132. As shown in FIG. 9, the rough surface area 131 and the non-rough surface area 132 may form a lattice pattern in which the rough surface area 131 has a lattice shape, or may form a circular pattern in which the non-rough surface area 132 has a circular shape, as shown in FIG. 10. Furthermore, as shown in FIG. 11, the non-rough surface area 132 may form a composite pattern having a plurality of shapes. In addition, the pattern of the rough surface area 131 and the non-rough surface area 132 may be a dot pattern, a check pattern, or the like, in which the rough surface area 131 and the non-rough surface area 132 are alternately arranged in the first direction (X direction in the figure) and the second direction (Y direction in the figure). Each of these patterns may also be formed on the entire first main surface 103b as shown in FIG. 7, or may be formed only on the main part.

The area ratio of the rough surface region 131 on the first main surface is preferably 30% or more and 90% or less, and the area ratio of the non-rough surface region 132 is preferably 10% or more and 70% or less. In each pattern, the size of the rough surface region 131 is not particularly limited, but it is preferably large enough to fit on the pad of a finger F, and is preferably 0.1 mm or more and 5 mm or less in diameter.

[First Surface Roughness]
The preferred range of the first surface roughness Rz1 was determined based on the following experiment. The tactile panel 103 used in the experiment had a roughened area 131 formed over the entire first main surface 103b, and did not have a non-roughened area 132.

Figure 12 is a graph showing the relationship between the first surface roughness Rz1 and contact sound, measuring the contact sound when the tactile panel 103 is vibrated by the piezoelectric actuator 104 and a finger is moved while touching the first main surface 103b. The contact sound is an abnormal sound generated by contact between the finger and the tactile panel 103, which vibrates in the ultrasonic band. As shown in the figure, when the first surface roughness Rz1 is small, the contact sound is large, and when the first surface roughness Rz1 is large, the contact sound is small. Specifically, when the first surface roughness Rz1 is 3 μm or more (arrow in the figure), the contact sound is small and is preferable.

Figure 13 is a graph showing the relationship between the first surface roughness Rz1 and friction noise, measuring friction noise when a finger is moved in contact with the first main surface 103b without vibrating the tactile panel 103. Friction noise is noise generated by friction between the first main surface 103b and the finger. As shown in the figure, when the first surface roughness Rz1 is small, the friction noise is small, and when the first surface roughness Rz1 is large, the friction noise is large. Specifically, when the first surface roughness Rz1 is 20 μm or less (arrow in the figure), the friction noise is small and is preferable.

Figure 14 is a graph showing the relationship between the first surface roughness Rz1 and the tactile sensation, in which the tactile panel 103 is vibrated by the piezoelectric actuator 104 and the tactile sensation is judged when a finger is moved while in contact with the first main surface 103b. The tactile sensation was judged as "good" if the finger felt a sufficient floating sensation due to the vibration of the tactile panel 103, and "poor" if the floating sensation was insufficient. As shown in the figure, a small first surface roughness Rz1 results in a good tactile sensation, and a large first surface roughness Rz1 results in a poor tactile sensation. Specifically, a first surface roughness Rz1 of 20 μm or less (arrow in the figure) results in a good tactile sensation, which is preferable.

From the above, when the first surface roughness Rz1 is 3 μm or more and 20 μm or less, contact noise and friction noise are suppressed, and a good tactile sensation can be obtained.

[Regarding the area ratio of the rough surface region]
A suitable range of the area ratio of the rough surface region 131 was determined based on the following experiment. The area ratio of the rough surface region 131 is the ratio of the area of the rough surface region 131 to the area of the first main surface 103b, with "0%" indicating that the entire first main surface 103b is the non-rough surface region 132 and "100%" indicating that the entire first main surface 103b is the rough surface region 131. "50%" indicates that the checkered pattern shown in Fig. 8 is formed, and "75%" indicates that the checkered pattern shown in Fig. 9 is formed. The first surface roughness Rz1 is 6 μm.

Figure 15 is a graph showing the relationship between the area ratio of the rough surface area 131 and contact noise, measuring the contact noise when the tactile panel 103 is vibrated by the piezoelectric actuator 104 and a finger is moved while touching the first main surface 103b. As shown in the figure, when the area ratio of the rough surface area 131 is small, the contact noise is large, and when the area ratio of the rough surface area 131 is large, the contact noise is small. Specifically, when the area ratio of the rough surface area 131 is 30% or more, the contact noise is small and is preferable.

Figure 16 is a graph showing the relationship between the area ratio of the rough surface area 131 and friction noise, measuring the friction noise when a finger is moved in contact with the first main surface 103b without vibrating the tactile panel 103. As shown in the figure, when the area ratio of the rough surface area 131 is small, the friction noise is small, and when the area ratio of the rough surface area 131 is large, the contact noise is large. Specifically, when the area ratio of the rough surface area 131 is 90% or less, the friction noise is small and is preferable.

Figure 17 is a graph showing the relationship between the area ratio of the rough surface area 131 and the tactile sensation, in which the tactile panel 103 is vibrated by the piezoelectric actuator 104, and the tactile sensation is judged when a finger is moved while in contact with the first main surface 103b. As shown in the figure, a small area ratio of the rough surface area 131 results in a good tactile sensation, and a large area ratio of the rough surface area 131 results in a poor tactile sensation. Specifically, an area ratio of the rough surface area 131 of 90% or less results in a good tactile sensation, which is preferable.

From the above, if the area ratio of the rough surface area 131 is 30% or more and 90% or less, contact noise and friction noise can be suppressed and a good tactile sensation can be obtained.

[Method of forming rough surface region]
The method for forming the rough surface region 131 is not particularly limited, but examples include a method of using a mold with a processed surface when molding the tactile panel 103, and a method of performing cutting or surface treatment after molding. The region of the first main surface 103b where the rough surface region 131 is not formed becomes the non-rough surface region 132.

[Effects of the display device]
As described above, in the display device 100, by forming a pattern consisting of rough areas 131 and non-rough areas 132 on the first main surface 103b of the tactile panel 103, it is possible to suppress contact noise and friction noise and present a good tactile sensation.

For comparison, Figure 18 is a graph showing the sound pressure characteristics of a tactile panel that does not have a rough surface area. In the figure, "with finger contact" indicates the sound pressure measured when the tactile panel is vibrated and a finger is moved while touching the tactile panel, while "without finger contact" indicates the sound pressure measured when the tactile panel is vibrated and a finger is not touching the tactile panel. Also in the figure, the input frequency to the piezoelectric actuator is shown as "input frequency," and a frequency that is 1/4 of this input frequency is shown as "1/4 frequency." Note that the input frequency is in the ultrasonic band, which is outside the audible band, but the 1/4 frequency is included in the audible band.

As shown in the figure, with "no finger contact," a peak exists at the input frequency, but no peak exists at the 1/4 frequency. On the other hand, with "finger contact," peaks exist at the input frequency and the 1/4 frequency. This indicates that with "finger contact," a contact sound occurs at the 1/4 frequency.

Figure 19 is a graph showing the sound pressure characteristics of the tactile panel 103 according to the present invention. The first surface roughness Rz1 is 6 μm. In the figure, "with finger contact" indicates the sound pressure measured when the tactile panel 103 is vibrated and a finger is moved while touching the first main surface 103b, and "without finger contact" indicates the sound pressure measured when the tactile panel 103 is vibrated and a finger is not touching the tactile panel 103. In the figure, the input frequency to the piezoelectric actuator 104 is shown as "input frequency", and a frequency that is 1/4 of this input frequency is shown as "1/4 frequency".

As shown in the figure, with "no finger contact," a peak exists at the input frequency, but no peak exists at the 1/4 frequency. Also, with "finger contact," a peak exists only at the input frequency, and no peak exists at the 1/4 frequency. Therefore, it can be seen that no contact sound is generated even with "finger contact."

As described above, the display device 100 according to the present invention can prevent the generation of contact noise by providing the rough surface area 131. Furthermore, the area ratio of the first surface roughness Rz1 to the rough surface area 131 can prevent the generation of friction noise and prevent a decrease in the tactile sensation. Therefore, the present invention can realize a display device that suppresses both contact noise and friction noise and provides an excellent tactile sensation due to ultrasonic vibrations.

100: Display device 101: Display panel 102: Touch panel 103: Tactile panel 104: Piezoelectric actuator 131: Rough surface area 132: Non-rough surface area

Claims (7)

a tactile panel having a first major surface and a second major surface opposite the first major surface;
a piezoelectric actuator disposed on the second main surface and configured to generate vibrations;
the first main surface has a roughened region having a surface roughness Rz of a first surface roughness and a non-roughened region having a second surface roughness Rz of 0.001 to 0.8 times the first surface roughness, and an area ratio of the roughened region on the first main surface is 30% to 90%,
The rough surface regions and the non-rough surface regions are alternately arranged over the entire surface of the first main surface in a first direction parallel to the first main surface and in a second direction parallel to the first main surface and perpendicular to the first direction.
Display device. The display device according to claim 1 ,
The display device, wherein the first surface roughness is equal to or greater than 3 μm and equal to or less than 20 μm. The display device according to claim 2,
The display device, wherein the second surface roughness is 0.003 μm or more and 16 μm or less. The display device according to claim 3,
The display device, wherein the second surface roughness is 0.05 μm or more and 10 μm or less. The display device according to any one of claims 1 to 4,
The diameter of the rough surface area is 0.1 mm or more and 5 mm or less.
Display device. The display device according to any one of claims 1 to 5,
The tactile panel is a display device made of resin or glass. a tactile panel having a first major surface and a second major surface opposite the first major surface;
a piezoelectric actuator disposed on the second main surface and configured to generate vibrations;
the first main surface has a roughened region having a surface roughness Rz of a first surface roughness and a non-roughened region having a second surface roughness Rz of 0.001 to 0.8 times the first surface roughness, and an area ratio of the roughened region on the first main surface is 30% to 90%,
The rough surface regions and the non-rough surface regions are alternately arranged over the entire surface of the first main surface in a first direction parallel to the first main surface and in a second direction parallel to the first main surface and perpendicular to the first direction.
electronic equipment.