JP2012048355A - Touch pad and capacitive sensor sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin touch pad and capacitive sensor sheet.SOLUTION: A touch pad 1 for detecting adjacency of an input object 100 and a position of the input object 100 when the input object 100 is adjacent to the touch pad includes: a tabular protection plate 2 having light permeability; a light guide 4 provided on the protection plate 2 and transferring illumination light L to the protection plate 2; a reflection member 6 provided on the light guide 4 and having a reflection surface 6a for reflecting the illumination light L toward the protection plate 2 side; and an electrode part 7 provided on a back surface 6b opposite to the side with the reflection surface 6a on the reflection member 6 and detecting change in capacitance between the input object 100 and the electrode part.

Description

  The present invention relates to a touch pad and a capacitance sensor sheet.

2. Description of the Related Art Conventionally, an input device that detects an input operation on an electronic device or the like using a change in capacitance is known. As an example of such an input device, for example, when an input body such as an operator's finger operating an electronic device or the like approaches, an electrostatic capacitance type device that detects the proximity of the input body and the position of the input body A touchpad can be mentioned.
Generally, a capacitive touch pad includes a sensor sheet for detecting a change in electrostatic capacitance with the input body. For example, Patent Document 1 discloses an insert sheet (sensor sheet) in which a conductive ink layer is formed on a base sheet and integrated with a molding resin by insert molding.

Japanese Patent Application No. 2009-238661

  However, since the base sheet that supports the conductive ink layer is indispensable for the insert sheet described in Patent Document 1, there is a limit to reducing the thickness of the insert sheet, and the touch pad is made thin. It was difficult.

  The present invention has been made in view of the above-described circumstances, and an object thereof is to provide a thin touch pad and a capacitance sensor sheet.

In order to solve the above problems, the present invention proposes the following means.
The touchpad of the present invention is a touchpad that detects the proximity of the input body and the position of the input body when the input body approaches, a plate-shaped protective plate having light transparency, A light guide that is provided on the protective plate and transmits illumination light to the protective plate, a reflective member that is provided on the light guide and has a reflective surface that reflects the illumination light toward the protective plate, and the reflective surface of the reflective member And an electrode portion for detecting a change in capacitance between the input body and the input body.

  The light guide is formed in a plate shape having a thickness in the thickness direction of the protective plate and is provided on one side in the thickness direction of the protective plate, and the reflective surface of the reflective member is the light You may contact the surface on the opposite side to the attachment surface of the said protective plate in a guide.

  The light guide is formed in a plate shape having a thickness in the thickness direction of the protective plate and is provided on one side in the thickness direction of the protective plate, and is provided between the reflecting member and the light guide. May be provided with an adhesive layer for bonding the reflecting member and the light guide together.

  The capacitance sensor sheet of the present invention is a capacitance sensor sheet used for a touch pad that detects the proximity of the input body and the position of the input body when the input body approaches, In order to detect a change in capacitance between the reflecting member having a reflecting surface that diffuses and reflects on one surface in the thickness direction and the input body, the other surface in the thickness direction of the reflecting member is used. An electrode portion formed directly and a wiring connected to the electrode portion are provided.

  According to the touch pad and the capacitance sensor sheet of the present invention, since the electrode portion is directly formed on the opposite side of the reflection surface of the reflection member, a thin touch pad and a capacitance sensor sheet can be obtained.

(A) is a perspective view of the touchpad of one Embodiment of this invention, (B) is a top view of the touchpad. It is AA sectional drawing of FIG. 1 (B). It is a figure which shows the reflective member in the same touchpad, (A) has shown the reflective surface, (B) has shown the back surface. It is a figure which shows the electrode arrangement | positioning of the electrostatic capacitance sensor sheet | seat in the same touchpad. (A) is a figure for demonstrating the effect | action of a touchpad, AA sectional drawing of FIG. 1 (B), (B) is a figure which shows the structure of a general touchpad for a comparison. (A) is a top view which shows the other structural example of the touchpad of this invention, (B) is BB sectional drawing of (A).

A touch pad 1 and a capacitance sensor sheet 5 according to an embodiment of the present invention will be described with reference to the drawings.
FIG. 1A is a perspective view of the touch pad 1. FIG. 1B is a plan view of the touch pad 1. FIG. 2 is a cross-sectional view taken along the line AA in FIG. In FIG. 2, the gaps between the constituent elements are highlighted for easy explanation.

  As shown in FIG. 1A, FIG. 1B, and FIG. 2, the touch pad 1 is for detecting the proximity of the input body 100 and the position of the input body 100. The input body 100 used together with the touch pad 1 is made of a conductor. For example, a stylus pen or a human finger can be used as the input body 100. An operator who performs an input operation on the touch pad 1 brings the input body 100 close to or in contact with the upper surface of a protection plate 2 described later, or slides the input body 100 along the upper surface of the touch pad 1. Can do.

  The touch pad 1 includes a protection plate 2, a light source 3 and a light guide 4, and a capacitance sensor sheet 5. The protection plate 2, the light guide 4, and the capacitance sensor sheet 5 are all thin plates, sheets, or films, and are arranged in this order from top to bottom. The shape of the touch pad 1 is a substantially plate shape having a thickness in the same direction as the thickness direction of the protection plate 2, the light guide 4, and the capacitance sensor sheet 5.

  The upper surface of the protection plate 2 is hard, and the input body 100 for performing an input operation can be brought into contact with the upper surface. The protective plate 2 is a light-transmitting rectangular plate-like member. Examples of the material of the protective plate 2 include polyethylene terephthalate (PET), polycarbonate, acrylic resin, ABS resin, and urethane. The upper surface of the protective plate 2 can be smoothed or can be appropriately decorated by unevenness or coloring. The lower surface of the protection plate 2 is formed smoothly. Note that the lower surface of the protective plate 2 may be roughened by, for example, sandblasting or etching. If the protective plate 2 and the light guide 4 are in close contact with each other, light leakage may occur from the portion where the protective plate 2 and the light guide 4 are in close contact, but by making the lower surface of the protective plate 2 rough. The protective plate 2 and the light guide 3 can be prevented from coming into close contact with each other.

  The light source 3 is for irradiating the light guide 4 with the illumination light L. In the present embodiment, a light emitting diode (LED) is adopted as the light source 3. The light source 3 irradiates the illumination light L onto the side surface of the light guide 4 and causes the illumination light L to enter the light guide 4 from the side surface of the light guide 4.

  The light guide 4 is a rectangular plate-like member that is provided on the lower surface of the protection plate 2 and has a thickness in the thickness direction of the protection plate 2. The light guide 4 has light transmittance, and the illumination light L emitted from the light source 3 is incident thereon. The illumination light L that has entered the light guide 4 travels through the light guide 4 and is emitted out of the light guide 4 from both sides in the thickness direction of the light guide 4. The illumination light L emitted from the upper surface of the light guide 4 is emitted upward from the upper surface of the protection plate 2 through the protection plate 2, and the illumination light L emitted from the lower surface of the light guide 4 is directed to the capacitance sensor sheet 5. Irradiated. As the material of the light guide 4, acrylic resin, polycarbonate, urethane, silicone rubber, or the like can be used. Moreover, you may provide patterns, such as a character and a pattern, on the surface of the light guide 4 using light-diffusion ink. In this case, the portion where the pattern is formed looks bright when viewed from the top to the bottom in the thickness direction of the touch pad.

3A and 3B are diagrams showing the reflecting member 6 of the capacitance sensor sheet 5, where FIG. 3A shows the reflecting surface 6a and FIG. 3B shows the back surface 6b.
As shown in FIGS. 2 and 3, the capacitance sensor sheet 5 includes a reflective member 6, and electrode portions 7 and wirings 10 that are directly formed on the lower surface of the reflective member 6.

  The reflecting member 6 is formed in the shape of a thin plate, sheet, or film, and is disposed in contact with the lower surface of the light guide 4 as shown in FIG. As shown in FIG. 2, the upper surface of the reflecting member 6 is a reflecting surface 6 a that reflects the illumination light L emitted from the lower surface of the light guide 4 upward. As shown in FIGS. 1A and 1B, the reflecting member 6 has a substantially rectangular shape that is substantially the same shape as the protective plate 2 when viewed from the thickness direction, and the reflecting member 6 is viewed from the thickness direction. A connecting portion 6c that protrudes in a rectangular shape from one place on the periphery when viewed is formed. As a material of the reflecting member 6, polyethylene terephthalate (PET), polycarbonate, acrylic resin, urethane, or the like can be used.

As shown in FIG. 3A, the reflecting surface 6a is formed into a rough surface having fine irregularities. In order to roughen the reflecting surface 6a, the surface can be roughened by, for example, sandblasting or etching, or fine particles such as silica beads can be fixed to the upper surface of the reflecting member 6. As a result, the illumination light L emitted from the lower surface of the light guide 4 diffuses in the rough surface portion of the reflection surface 6a, and the component of the illumination light L directed upward in the thickness direction of the touch pad 1 as shown in FIG. Is emitted from the upper surface of the protective plate 2 through the light guide 4 and the protective plate 2.
The reflective surface 6a may be roughened into a pattern such as a character or a pattern. In this case, the pattern-formed portion looks bright when viewed from the top to the bottom in the thickness direction of the touch pad 1.

FIG. 4 is a diagram showing the electrode arrangement of the capacitance sensor sheet 5. 4 shows a state viewed from the back surface 6b of the capacitance sensor sheet 5. FIG.
As shown in FIGS. 3 and 4, the electrode unit 7 has a back surface 6b (lower surface) opposite to the reflective surface 6a in order to detect a change in capacitance with the input body 100 (see FIG. 2). ), And includes a first detection electrode 8, a second detection electrode 9, and an insulating material 13.

  As shown in FIG. 3B, a plurality of first detection electrodes 8 are formed on the lower surface of the reflecting member 6 (the back surface 6b of the reflecting surface 6a) so as to extend in one direction and in parallel with each other. Five first detection electrodes 8 are formed, and each first detection electrode 8 has a square shape when viewed from the thickness direction of the first detection electrode 8 and the vertexes of the diagonals are connected to each other. And a plurality of first electrode elements 8a.

  In the present embodiment, seven first electrode elements 8 a are provided for each first detection electrode 8. The first electrode elements 8a are arranged in a line in the first detection electrodes 8. The first detection electrodes 8 adjacent to each other are arranged such that the apexes of the first electrode elements 8a are adjacent to each other with a gap. In addition, a substantially square gap is formed between the first detection electrodes 8. The size of the substantially square gap between the first detection electrodes 8 is larger than the contour when a second electrode element 9a described later is viewed from the thickness direction of the second electrode element 9a.

  The material of the first detection electrode 8 may be any conductive material having conductivity. For example, a thin plate such as copper, gold, silver, or aluminum, a metal foil, or a paste containing metal particles may be employed. . In the present embodiment, the first detection electrode 8 is made of a silver paste.

  As shown in FIG. 3B, the second detection electrode 9 is parallel to one direction intersecting the lower surface of the reflecting member 6 (the back surface 6b of the reflecting surface 6a) with respect to the direction in which each first detecting electrode 8 extends. A plurality of them are formed. Six second detection electrodes 9 are formed, and each second detection electrode 9 has a square shape when viewed from the thickness direction of the second detection electrode 9 and the opposite vertexes are connected to each other. And a plurality of second electrode elements 9a.

The second electrode elements 9 a are arranged in a line in each second detection electrode 9. In the present embodiment, six second electrode elements 9 a are provided for each second detection electrode 9. The second detection electrodes 9 adjacent to each other are arranged so that the apexes of the second electrode elements 9a are adjacent to each other with a gap therebetween, and a substantially square gap is formed between the adjacent second detection electrodes 9. It is vacant. The size of the substantially square gap between the second detection electrodes 9 is larger than the contour when the first electrode element 8a is viewed from the thickness direction of the first electrode element 8a.
The material of the second detection electrode 9 can be appropriately selected from conductive materials in the same manner as the material of the first detection electrode 8.

The wiring 10 includes a first wiring 11 connected to each first detection electrode 8 and a second wiring 12 connected to each second detection electrode 9.
The first wiring 11 is provided on the lower surface of the reflecting member 6 (the back surface 6 b of the reflecting surface 6 a) and is a wiring made of a conductor pattern connected to the first detection electrode 8. One end of the first wiring 11 is connected to each first detection electrode 8, and the other end of the first wiring 11 extends to the tip of the connection portion 6 c through the outer region of the plurality of first detection electrodes 8. At the tip of the connection portion 6c, the other end of the first wiring 11 is arranged at equal intervals according to the pitch of contact terminals in a connector for a flexible printed circuit board (FPC) or a flexible flat cable (FFC).

  The line width of the first wiring 11 measured along the surface direction of the reflecting member 6 is smaller than the maximum dimension in the surface direction of the first electrode element 8a. As the material of the first wiring 11, a conductive material similar to that of the first detection electrode 8 can be appropriately selected and employed. In the present embodiment, the first wiring 11 is made of the same silver paste as the first detection electrode 8. If the 1st wiring 11 is formed with the same material as the 1st detection electrode 8, the 1st wiring 11 and the 1st detection electrode 8 can be collectively formed in the same process. Furthermore, if the first wiring 11 is formed of the same material as that of the first detection electrode 8, the electrolytic corrosion at the contact portion between the first detection electrode 8 and the first wiring 11 can be suppressed as compared with the case where a different metal contacts. You can also

The second wiring 12 is provided on the lower surface of the reflecting member 6 (the back surface 6 b of the reflecting surface 6 a) and is a wiring made of a conductor pattern connected to the second detection electrode 9. One end of the second wiring 12 is connected to each second detection electrode 9, and the other end of the second wiring 12 extends to the tip of the connection portion 6 c through the outer region of the plurality of second detection electrodes 9. The second wiring 12 extends in parallel with the first wiring 11 at the connection portion 6c. At the tip of the connecting portion 6c, the other end of the second wiring 12 is arranged at the same pitch as the other end of the first wiring 11 and arranged at equal intervals.
The line width of the second wiring 12 measured along the surface direction of the reflecting member 6 is smaller than the maximum dimension of the second electrode element 9a. The material of the second wiring 12 can be appropriately selected from conductive materials in the same manner as the material of the first wiring 11.

As shown in FIG. 4, the first detection electrode 8 and the second detection electrode 9 are arranged such that the second electrode element of the second detection electrode 9 is in a square gap between the first detection electrodes 8. 9a is stored.
The insulating material 13 is an insulating thin plate member provided at a position where the first detection electrode 8 and the second detection electrode 9 overlap when viewed from the thickness direction of the reflecting member 6. The insulating material 13 is sandwiched between the first detection electrode 8 and the second detection electrode 9 and supports the first detection electrode 8 and the second detection electrode 9 in a non-contact state. Thereby, in the part which the 1st detection electrode 8 and the 2nd detection electrode 9 cross | intersect, the 1st detection electrode 8 and the 2nd detection electrode 9 are insulated.

Operations of the touch pad 1 and the capacitance sensor sheet 5 having the above-described configuration will be described.
FIG. 5A is a diagram for explaining the operation of the touch pad 1, and is a cross-sectional view taken along the line AA in FIG. FIG. 5B is a diagram showing a configuration of a general touch pad 1X different from the touch pad 1 of the present embodiment for comparison.
As shown in FIG. 5A, when the touch pad 1 is used, the illumination light L is irradiated from the light source 3 to the light guide 4. The illumination light L applied to the light guide 4 is transmitted through the inside of the light guide 4 and diffuses on the reflection surface 6a of the reflection member 6 and is reflected upward. Then, the reflected light enters the light guide 4 from the lower surface of the light guide 4, passes through the inside of the light guide 4, exits from the upper surface of the light guide 4, and enters the lower surface of the protection plate 2. The illumination light L incident on the lower surface of the protection plate 2 is emitted from the upper surface of the protection plate 2 through the inside of the protection plate 2.

  FIG. 5B shows a touch pad 1X including a general capacitance sensor sheet 5X different from the capacitance sensor sheet 5 of the present invention. In the touch pad 1X, no electrode is formed on the reflection member 6, and an electrode portion 7X for detecting a change in capacitance with the input body 100 is provided on the upper surface of the base sheet 15X. Yes. When the reflection member 6 as in the present application is provided on the conventional capacitance sensor sheet 5X, the electrode portion 7X is generally bonded to the back surface 6bX of the reflection member 6X having the reflection surface 6aX formed on the upper surface. .

  Conventionally, since the capacitance sensor sheet 5X having such a configuration is employed, the thickness H1X of the touch pad 1X is thicker than the thickness H1 of the touch pad 1 of the present embodiment by the amount of the base sheet 15X. turn into. Although not shown, for example, when the conventional electrostatic capacitance sensor sheet 5X is to be fixed to the back surface 6b of the reflecting member 6, the touch pad 1X becomes thicker by the amount of the adhesive or the adhesive sheet.

In the touch pad 1 of the present embodiment, the distance H2 between the upper surface of the protective plate 2 and the electrode portion 7 is the same as the distance H2X between the protective plate 2 and the electrode portion 7X in the conventional touch pad 1X. When the input body 100 approaches, the pad 1 can detect the proximity of the input body 100 and the position of the input body 100 with detection sensitivity equivalent to that of the conventional touch pad 1X.
As a result, the touch pad 1 can be configured to be thinner while maintaining detection sensitivity equivalent to that of the prior art.

  As described above, according to the touch pad 1 and the capacitive sensor sheet 5 of the present embodiment, the electrode portion 7 is directly formed on the opposite side of the reflective surface 6a of the reflective member 6, and thus a thin touch pad. 1 and the capacitance sensor sheet 5.

Moreover, since the electrode part 7 is provided in the lower surface (back surface 6b of the reflective surface 6a) of the reflection member 6, the illumination light L can be reflected suitably in the reflective surface 6a irrespective of the material of the electrode part 7. FIG.
In addition, since both the first detection electrode 8 and the second detection electrode 9 are provided on the lower surface of the reflecting member 6, the shortest distance from the upper surface of the protection plate 2 to the first detection electrode 8 and the second surface from the upper surface of the protection plate 2. The shortest distance to the detection electrode 9 is equal. Thereby, it becomes easy to make detection sensitivity in the 1st detection electrode 8 and detection sensitivity in the 2nd detection electrode 9 comparable.

  The embodiments of the present invention and the modifications thereof have been described in detail with reference to the drawings. However, the specific configuration is not limited to the embodiments and the modifications, and the design does not depart from the gist of the present invention. Changes are also included.

  For example, in the above-described embodiment, the example in which the lower surface of the light guide 4 and the upper surface of the reflecting member 6 (the reflecting surface 6a) are in contact with each other has been described, but between the lower surface of the light guide 4 and the upper surface of the reflecting member 6 is described. There may be space. FIG. 6A and FIG. 6B show another configuration example of the touch pad 1. FIG. 6A is a plan view showing the touch pad 1A of this configuration example. FIG. 6B is a cross-sectional view taken along the line BB in FIG.

As shown in FIGS. 6A and 6B, an adhesive layer 16 disposed along the peripheral edge of the light guide 4 is provided between the reflecting member 6 and the light guide 4.
The adhesive layer 16 is a thin plate, a film, a sheet, or a film-like member having a central portion cut out in a rectangular shape, leaving only a position overlapping the peripheral edge of the light guide 4, and both sides in the thickness direction are adhesive. Have Thereby, a space is provided between the reflecting member 6 and the light guide 4. By making a space between the reflecting member 6 and the light guide 4, it is possible to prevent light from leaking from the light guide 4 to the lower surface due to a refractive index difference between the light guide 4 and air.

Further, the adhesive layer 16 may be one in which a liquid adhesive is cured and the reflecting member 6 and the light guide 4 are bonded together.
The adhesive layer 16 may cover the entire lower surface of the light guide 4 and the upper surface of the reflecting member 6 (the reflecting surface 6a). In this case, the adhesive layer 16 is preferably a light transmissive member having a refractive index equivalent to that of the light guide 4 or a refractive index lower than that of the light guide 4. By making the refractive index of the adhesive layer 16 lower than the refractive index of the light guide 6, it is possible to prevent light from leaking from the light guide 4 to the lower surface.
By providing the adhesive layer 16 between the reflecting member 6 and the light guide 4, the reflecting member 6 and the light guide 4 can be reliably fixed.

DESCRIPTION OF SYMBOLS 1, 1A Touchpad 2 Protection board 3 Light source 4 Light guide 5 Capacitance sensor sheet 6 Reflective member 7 Electrode part 8 First detection electrode 9 Second detection electrode 10 Wiring 11 First wiring 12 Second wiring 13 Insulating material 16 Adhesion layer

Claims (4)

A touchpad that detects the proximity of the input body and the position of the input body when the input body is close;
A plate-shaped protective plate having light transparency;
A light guide that is provided on the protective plate and transmits illumination light to the protective plate;
A reflecting member provided on the light guide and having a reflecting surface that reflects the illumination light toward the protective plate;
Provided on the back surface of the reflective member opposite to the reflective surface, an electrode portion for detecting a change in electrostatic capacitance between the input body,
A touchpad comprising: The light guide is formed in a plate shape having a thickness in the thickness direction of the protection plate and is provided on one side in the thickness direction of the protection plate,
The touch pad according to claim 1, wherein the reflection surface of the reflection member is in contact with a surface of the light guide opposite to the mounting surface of the protection plate. The light guide is formed in a plate shape having a thickness in the thickness direction of the protection plate and is provided on one side in the thickness direction of the protection plate,
The touch pad according to claim 1, wherein an adhesive layer for bonding the reflective member and the light guide is disposed between the reflective member and the light guide. A capacitive sensor sheet used for a touchpad that detects the proximity of the input body and the position of the input body when the input body is in proximity,
A reflecting member having a reflecting surface that diffuses and reflects light on one surface in the thickness direction;
An electrode portion directly formed on the other surface in the thickness direction of the reflecting member in order to detect a change in capacitance between the input body and the input body;
Wiring connected to the electrode part;
A capacitance sensor sheet comprising:

Images