Display device and electronic equipment

Abstract

To provide a display device and an electronic apparatus that suppress contact sound and fricative sound and are excellent in tactile sensation due to ultrasonic vibration.SOLUTION: A display device according to the present invention includes a haptic panel and a piezoelectric actuator. The haptic panel has a first principal surface and a second principal surface opposite the first principal surface. The piezoelectric actuator is disposed on the second principal surface and generates vibration. The first principal surface has a rough surface area where surface roughness Rz is first surface roughness, and a non-rough surface area where surface roughness Rz is second surface roughness of 0.001 times or more and 0.8 times or less the first surface roughness. The area ratio of the rough surface area in the first principal surface is 30% or more and 90% or less.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a display device and an electronic device capable of tactile presentation.

Background Art

[0002] Some smartphones, car navigation systems, etc. are equipped with a force feedback function that causes vibration when a touch panel is operated to notify that an input has been received. In recent years, not only vibration for notification but also tactile technologies that can express the feel of a displayed object or grasp the operation position by varying the vibration in various ways have been studied and developed.

[0003] Such a tactile technology can be realized by vibrating a piezoelectric actuator joined to a tactile panel at a frequency in the ultrasonic band. A standing wave is formed on the tactile panel by the vibration in the ultrasonic band, and when the tactile panel is touched with a finger or the like, the tactile sensation can be sensed. By changing the signal pattern supplied to the piezoelectric actuator, various variations of tactile sensations can be expressed.

[0004] Here, when the surface of the vibrating tactile panel is touched with a finger or the like, a contact sound may be generated. In contrast, Patent Document 1 discloses a touch panel display that reduces the contact sound by making the surface roughness of the tactile panel surface rough.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] However, as described in Patent Document 1, although reducing the surface roughness of the surface of the tactile panel can reduce the contact sound, the tactile sensation due to the vibration of the tactile panel deteriorates. Further, when the finger is moved while the tactile panel is not vibrating, a frictional sound is generated due to the friction between the tactile panel and the finger or the like.

[0007] In view of the above circumstances, an object of the present invention is to provide a display device and an electronic device in which contact sound and frictional sound are suppressed and which are excellent in tactile sensation due to ultrasonic vibration.

Means for Solving the Problems

[0008] 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 main surface and a second main surface on the side opposite to the first main surface. The piezoelectric actuator is disposed on the second main surface and generates vibration. The first main surface has a rough surface region where the surface roughness Rz is a first surface roughness, and a non-rough surface region where the surface roughness Rz is 0.001 times or more and 0.8 times or less of the first surface roughness. The area ratio of the rough surface region on the first main surface is 30% or more and 90% or less.

[0009] The first surface roughness may be 3 μm or more and 20 μm or less.

[0010] The second surface roughness may be 0.003 μm or more and 16 μm or less.

[0011] The second surface roughness may be 0.05 μm or more and 10 μm or less.

[0012] The rough surface region and the non-rough surface region may be alternately arranged 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.

[0013] The tactile panel may be made of resin or glass.

[0014] To achieve the above object, an electronic device according to an aspect of the present invention includes a tactile panel and a piezoelectric actuator. The tactile panel has a first main surface and a second main surface opposite to the first main surface. The piezoelectric actuator is disposed on the second main surface and generates vibration. The first main surface has a rough surface region where the surface roughness Rz is a first surface roughness, and a non-rough surface region where the surface roughness Rz is 0.001 times or more and 0.8 times or less of the first surface roughness. The area ratio of the rough surface region on the first main surface is 30% or more and 90% or less.

Advantages of the Invention

[0015] As described above, according to the present invention, it is possible to provide a display device and an electronic device in which contact sounds and frictional sounds are suppressed and the tactile sensation by ultrasonic vibration is excellent.

Brief Description of the Drawings

[0016]

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Embodiments for Carrying Out the Invention

[0017] Hereinafter, the display device according to the present embodiment will be described.

[0018] [Configuration of 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 and is a cross-sectional view taken along line A-A in FIGS. 2 and 3.

[0019] As shown in these figures, the display device 100 includes a display panel 101, a touch panel 102, a tactile panel 103, and a piezoelectric actuator 104. As shown in FIGS. 2 and 3, the display device 100 is flat and has a rectangular shape when viewed from a direction perpendicular to the thickness direction. In each figure of the present disclosure, the longitudinal direction of the display device 100 is the X direction, the short transverse direction is the Y direction, and the thickness direction is the Z direction.

[0020] The display panel 101 is a panel for displaying images, and is a display panel using liquid crystal, organic EL (electro-luminescence), or the like. The configuration of the display panel 101 is not particularly limited, and it can be a display having a general configuration.

[0021] The touch panel 102 is disposed on the display panel 101 and detects a touch on the display device 100 by a user's finger or the like. The touch panel 102 includes arranged touch sensors, and the touch sensors are preferably of the capacitance type. The touch panel 102 may be one in which a touch panel main body and a protective cover glass are laminated, or may be one in which the touch panel main body and the protective cover glass are integrated.

[0022] 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 long side than other members such as the touch panel 102 and has a portion 103a that protrudes from other members. A piezoelectric actuator 104 is joined to this portion 103a, and vibration is generated by the piezoelectric actuator 104. The tactile panel 103 is made of a light-transmissive material such as glass or resin. As shown in FIG. 4, the main surface of the tactile panel 103 on the side opposite to the touch panel 102 is defined as the first main surface 103b, and the main surface on the touch panel 102 side and opposite to the first main surface 103b is defined as the second main surface 103c. A rough area and a non-rough area are provided on the first main surface 103b. These areas will be described later.

[0023] The piezoelectric actuator 104 is joined to the tactile panel 103 and generates vibration. As shown in FIG. 1, the piezoelectric actuator 104 is joined to the second main surface 103c at the portion 103a of the tactile panel 103. 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).

[0024] 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 a plurality of layers are provided 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 a plurality of layers are provided 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.

[0025] As shown in FIG. 5, the first internal electrode 124 and the second internal electrode 126 are alternately arranged and face each other through the piezoelectric body 121. Note that the number of layers of the first internal electrode 124 and the second internal electrode 126 is not limited to three layers each. As shown in FIGS. 2 and 3, a first wiring 128 is connected to the first electrode 122, and a second wiring 129 is connected to the second electrode 123. The first wiring 128 and the second wiring 129 are connected to a driving unit (not shown), and transmit a driving signal output from the driving unit to the first electrode 122 and the second electrode 123.

[0026] When a voltage is applied between the first electrode 122 and the second electrode 123 by this driving signal, deformation occurs in the piezoelectric body 121 due to the inverse piezoelectric effect, and vibration is generated. Here, in the display device 100, the control unit supplies an ultrasonic driving signal to the piezoelectric actuator 104, so that vibration in the ultrasonic band (20 kHz or higher) can be generated in the piezoelectric actuator 104. Note that the piezoelectric actuator 104 may have a laminated structure in which the first electrode 122 and the second electrode 123 are alternately laminated via the piezoelectric body 121 as shown in FIG. 5, or may have another structure.

[0027] The display device 100 has the above configuration. The display device 100 can be mounted on an electronic device such as a smartphone.

[0028] [Regarding the operation of the display device] The operation of the display device 100 will be described. FIG. 6 is a schematic diagram showing the operation of the display device 100. As shown in the figure, when the piezoelectric actuator 104 (see FIG. 1) is vibrated in the ultrasonic band with the user's finger F in contact with the first main surface 103b of the tactile panel 103, the vibration is transmitted to the tactile panel 103, and the tactile panel 103 vibrates. As a result, the finger F can sense the touch.

[0029] Also, the contact of the finger F with the tactile panel 103 is detected by the touch panel 102. Further, the image displayed by the display panel 101 is visible through the touch panel 102 and the tactile panel 103.

[0030] [Regarding the first main surface] As described above, a rough surface region and a non-rough surface region 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 region 131 and a non-rough surface region 132 are formed on the first main surface 103b.

[0031] The rough surface region 131 is a roughened region, and the surface roughness Rz of the rough surface region 131 is defined as "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 defined as "second surface roughness Rz2". Note that the surface roughness Rz means the ten-point average roughness (defined by JIS B 0601:2001 (conforming to ISO4287-1997)).

[0032] It is preferable that the second surface roughness Rz2 is 0.001 times or more and 0.8 times or less of the first surface roughness Rz1. Specifically, the first surface roughness Rz1 is preferably 3 μm or more and 20 μm or less, and the second surface roughness Rz2 is preferably 0.003 μm or more and 16 μm or less. Also, the second surface roughness Rz2 is more preferably 0.05 μm or more and 10 μm or less.

[0033] As shown in FIGS. 7 and 8, the rough surface area 131 and the non-rough surface area 132 form a pattern, and are alternately arranged in a first direction (the X direction in the figure) parallel to the first main surface 103b and a second direction (the Y direction in the figure) parallel to the first main surface 103b and perpendicular to the first direction. As shown in FIGS. 7 and 8, the pattern can be a checkered pattern. As shown in FIG. 7, the pattern is formed over the entire first main surface 103b. Also, the pattern may be formed only on the main 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 the checkered pattern, and it is sufficient that the rough surface area 131 and the non-rough surface area 132 are alternately arranged in the first direction (the X direction in the figure) and the second direction (the Y direction in the figure).

[0034] FIGS. 9 to 11 are schematic views 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, and as shown in FIG. 10, the non-rough surface area 132 may form a circular pattern in which the non-rough surface area 132 has a circular shape. Further, as shown in FIG. 11, the non-rough surface area 132 may form a composite pattern having a plurality of shapes. In addition to this, the pattern of the rough surface area 131 and the non-rough surface area 132 may be a dot pattern, a check pattern, etc., as long as the rough surface area 131 and the non-rough surface area 132 are alternately arranged in the first direction (the X direction in the figure) and the second direction (the Y direction in the figure). Each of these patterns may also be formed over the entire first main surface 103b as shown in FIG. 7, or may be formed only on the main portion.

[0035] The area ratio of the rough surface area 131 on the first main surface is preferably 30% or more and 90% or less, and the area ratio of the non-rough surface area 132 is preferably 10% or more and 70% or less. In each pattern, the size of the rough surface area 131 is not particularly limited, but a size that fits within the pad of the finger F is preferable, and a diameter of 0.1 mm or more and 5 mm or less is preferable.

[0036] [Regarding the first surface roughness] The suitable range of the first surface roughness Rz1 was determined based on the following experiment. The tactile panel 103 used in the experiment has a rough surface area 131 formed on the entire surface of the first main surface 103b and does not have a non-rough surface area 132.

[0037] FIG. 12 is a graph showing the relationship between the first surface roughness Rz1 and the contact sound. The contact sound was measured when the tactile panel 103 was vibrated by the piezoelectric actuator 104 and the finger was moved while being in contact with the first main surface 103b. The contact sound is an abnormal sound generated by the contact between the tactile panel 103 vibrating in the ultrasonic band and the finger. 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 suitable.

[0038] FIG. 13 is a graph showing the relationship between the first surface roughness Rz1 and the frictional sound. The frictional sound was measured when the tactile panel 103 was not vibrated and the finger was moved while being in contact with the first main surface 103b. The frictional sound is a sound generated by the friction between the first main surface 103b and the finger. As shown in the figure, when the first surface roughness Rz1 is small, the frictional sound is small, and when the first surface roughness Rz1 is large, the frictional sound is large. Specifically, when the first surface roughness Rz1 is 20 μm or less (arrow in the figure), the frictional sound is small and suitable.

[0039] FIG. 14 is a graph showing the relationship between the first surface roughness Rz1 and the tactile sensation. The tactile sensation was determined when the tactile panel 103 was vibrated by the piezoelectric actuator 104 and the finger was moved while being in contact with the first main surface 103b. The tactile sensation was judged as "good" if a sufficient floating feeling could be felt with the finger due to the vibration of the tactile panel 103, and "bad" if the floating feeling was insufficient. As shown in the figure, when the first surface roughness Rz1 is small, the tactile sensation is good, and when the first surface roughness Rz1 is large, the tactile sensation is bad. Specifically, when the first surface roughness Rz1 is 20 μm or less (arrow in the figure), the tactile sensation is good and suitable.

[0040] From the above, when the first surface roughness Rz1 is 3 μm or more and 20 μm or less, contact sound and frictional sound can be suppressed, and a good tactile sensation can be obtained.

[0041] [Regarding the area ratio of the rough surface region] The preferable 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. "0%" indicates the case where the entire first main surface 103b is the non-rough surface region 132, and "100%" indicates the case where the entire first main surface 103b is the rough surface region 131. "50%" indicates the case where the checkered pattern shown in FIG. 8 is formed, and "75%" indicates the case where the checkered pattern shown in FIG. 9 is formed. The first surface roughness Rz1 is 6 μm.

[0042] FIG. 15 is a graph showing the relationship between the area ratio of the rough surface region 131 and the contact sound. The contact sound was measured when the tactile panel 103 was vibrated by the piezoelectric actuator 104 and the finger was moved while contacting the first main surface 103b. As shown in the figure, when the area ratio of the rough surface region 131 is small, the contact sound is large, and when the area ratio of the rough surface region 131 is large, the contact sound is small. Specifically, when the area ratio of the rough surface region 131 is 30% or more, the contact sound is small and suitable.

[0043] FIG. 16 is a graph showing the relationship between the area ratio of the rough surface region 131 and the frictional sound. The frictional sound was measured when the finger was moved while contacting the first main surface 103b without vibrating the tactile panel 103. As shown in the figure, when the area ratio of the rough surface region 131 is small, the frictional sound is small, and when the area ratio of the rough surface region 131 is large, the contact sound is large. Specifically, when the area ratio of the rough surface region 131 is 90% or less, the frictional sound is small and suitable.

[0044] FIG. 17 is a graph showing the relationship between the area ratio of the rough surface region 131 and the tactile sensation. The tactile panel 103 was vibrated by the piezoelectric actuator 104, and the tactile sensation was determined when the finger was moved while being in contact with the first main surface 103b. As shown in the figure, when the area ratio of the rough surface region 131 is small, the tactile sensation is good, and when the area ratio of the rough surface region 131 is large, the tactile sensation is poor. Specifically, when the area ratio of the rough surface region 131 is 90% or less, the tactile sensation is good and suitable.

[0045] From the above, when the area ratio of the rough surface region 131 is 30% or more and 90% or less, the contact sound and the frictional sound can be suppressed, and a good tactile sensation can be obtained.

[0046] [Method for forming the rough surface region] The method for forming the rough surface region 131 is not particularly limited, and examples include a method using a mold with surface processing when molding the tactile panel 103, and a method of performing cutting, surface treatment processing, etc. after molding. The region where the rough surface region 131 is not formed in the first main surface 103b becomes the non-rough surface region 132.

[0047] [Effect by the display device] In the display device 100, as described above, by forming a pattern composed of the rough surface region 131 and the non-rough surface region 132 on the first main surface 103b of the tactile panel 103, it is possible to suppress the contact sound and the frictional sound and present a good tactile sensation.

[0048] FIG. 18 is a graph showing the sound pressure characteristics of a tactile panel having no rough surface region for comparison. In the figure, "with finger contact" indicates the sound pressure measured in a state where the tactile panel is vibrated and the finger is moved while being in contact with the tactile panel, and "without finger contact" indicates the sound pressure measured in a state where the tactile panel is vibrated and the finger is not in contact with the tactile panel. Also, in the figure, the input frequency to the piezoelectric actuator is shown as "input frequency", and the 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 and is out of the audible band, but the 1 / 4 frequency is included in the audible band.

[0049] As shown in the figure, in the case of "no finger contact", there is a peak in the input frequency, but there is no peak in the 1 / 4 frequency. On the other hand, in the case of "finger contact", there are peaks in both the input frequency and the 1 / 4 frequency. This indicates that in the case of "finger contact", contact sounds are generated at the 1 / 4 frequency.

[0050] FIG. 19 is a graph showing the sound pressure characteristics in 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 in a state where the tactile panel 103 is vibrated and the finger is moved while being in contact with the first main surface 103b, and "without finger contact" indicates the sound pressure measured in a state where the tactile panel 103 is vibrated and the finger is not in contact with the tactile panel 103. Also, in the figure, the input frequency to the piezoelectric actuator 104 is shown as "input frequency", and the frequency that is 1 / 4 of this input frequency is shown as "1 / 4 frequency".

[0051] As shown in the figure, in the case of "no finger contact", there is a peak in the input frequency, but there is no peak in the 1 / 4 frequency. Also, in the case of "finger contact", there is a peak only in the input frequency, and there is no peak in the 1 / 4 frequency. Therefore, it can be seen that even in the case of "finger contact", no contact sound is generated.

[0052] As described above, in the display device 100 according to the present invention, by providing the rough surface area 131, the generation of contact sounds can be prevented. Also, by the area ratio of the first surface roughness Rz1 and the rough surface area 131, the generation of frictional sounds can be prevented and a decrease in the tactile sensation can be prevented. Therefore, according to the present invention, it is possible to realize a display device in which both contact sounds and frictional sounds are suppressed and which has an excellent tactile sensation due to ultrasonic vibration.

Explanation of Reference Numerals

[0053] 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

1. A tactile panel having a first main surface and a second main surface opposite to the first main surface, a piezoelectric actuator disposed on the second main surface and generating vibration, and comprising: the first main surface has a rough surface region where the surface roughness Rz is a first surface roughness, and a non-rough surface region where the surface roughness Rz is a second surface roughness that is 0.001 times or more and 0.8 times or less of the first surface roughness, and the area ratio of the rough surface region on the first main surface is 30% or more and 90% or less, the rough surface region and the non-rough surface region are alternately arranged over the entire surface of the first main surface 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. A display device.

2. The display device according to Claim 1, wherein the first surface roughness is 3 μm or more and 20 μm or less. A display device.

3. The display device according to Claim 2, wherein the second surface roughness is 0.003 μm or more and 16 μm or less. A display device.

4. The display device according to Claim 3, wherein the second surface roughness is 0.05 μm or more and 10 μm or less. A display device.

5. The display device according to any one of Claims 1 to 4, wherein the diameter of the rough surface region is 0.1 mm or more and 5 mm or less. A display device.

6. The display device according to any one of Claims 1 to 5, wherein the tactile panel is made of resin or glass. A display device.

7. An electronic device having a first main surface and a second main surface opposite to the first main surface, a piezoelectric actuator disposed on the second main surface and generating vibration, and comprising: the first main surface has a rough surface region where the surface roughness Rz is a first surface roughness, and a non-rough surface region where the surface roughness Rz is a second surface roughness that is 0.001 times or more and 0.8 times or less of the first surface roughness, and the area ratio of the rough surface region on the first main surface is 30% or more and 90% or less, the rough surface region and the non-rough surface region are alternately arranged over the entire surface of the first main surface 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. An electronic device.

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