JP2013106308A - Capacitive touch panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reliably detect approach or contact of an operating body such as a human finger even if the thickness of an operation panel of a resin or the like formed on a capacitive sensor is obliged to be greater than a predetermined value.SOLUTION: An electrode pad 20c for detecting approach or contact of an operating body is disposed on an undersurface of an operation panel 10 by an adhesive film 23. A part of a surface region of the operation panel 10 opposite to the region of the electrode pad 20c is provided with a recessed portion having a smaller thickness than the other region, and the recessed portion is embedded with a touch part 80c having a metal film formed by vacuum deposition on a surface of a resin material so as to provide such permittivity and conductivity as keeps a change in capacitance within a detection threshold in the absence of approach or contact of the operating body. When the operating body is in contact with the touch part 80c, the touch part 80c bridges the operating body and the electrode pad 20c for reliable detection of the contact of the operating body even if the operation panel 10 has a great thickness d2.

Description

  The present invention relates to a capacitive touch panel that detects an approach or contact of an operating body such as a fingertip of a human body as a change in capacitance.

  In recent years, touch panels have been widely used in operation units of various electronic devices. In particular, among various methods for realizing a touch panel, a capacitive touch panel that performs detection using a capacitive sensor has been widely adopted in various electronic devices (see, for example, Patent Document 1).

  Generally, a capacitance sensor is composed of an electrode pad formed of a transparent conductive film such as ITO (Indium Tin Oxide) and a wiring electrode for transmitting a change in capacitance of the electrode pad. Composed. In such a capacitance sensor, when an operating body such as a human fingertip approaches the electrode pad, the capacitance of the capacitor constituted by the electrode pad changes. By outputting to the control unit, it is possible to detect that the operation to the electrode pad has been performed on the control unit side.

  As described above, the capacitive touch panel has an advantage that durability is high because a mechanically operating mechanism is unnecessary, and adjustment of an operation feeling or the like is not necessary. In addition, the capacitive touch panel has the advantage that the thickness can be reduced, the operation surface can be made flat, the degree of freedom in layout and design is high, and the number of parts can be reduced. is there.

  However, since the capacitive touch panel detects the approach or contact of the operating tool by a subtle change in electrostatic capacity, there are various uses for detecting the approach or touch of the operating tool reliably without erroneous detection. Needs to be met.

  For example, in Patent Document 1 described above, in order to prevent malfunction of the capacitance sensor, a dummy electrode is formed around the regular switch electrode, and effective contact is made with the regular switch electrode. A capacitance-type touch panel for determining whether or not is disclosed.

  Such a capacitive touch panel is generally configured by attaching a capacitive sensor to the back surface of an operation panel made of a resin material. Therefore, when an operating body such as a fingertip of a human body approaches or indirectly contacts the electrode pad via the operating panel, a capacitor is formed by the operating body and the electrode pad. Since the capacitance of the formed capacitor is inversely proportional to the distance between the operating body and the electrode pad, the thickness of the operating panel is set to a predetermined value in order to reliably detect the approach or contact of the operating body. Need to be thin.

JP 2009-111996 A

  As described above, in order to reliably detect the approach or contact of the operation body in the capacitive touch panel, it is necessary to make the thickness of the operation panel thinner than a predetermined value.

  However, the thickness of the operation panel cannot be made very thin because it is necessary to ensure the strength of the operation panel itself or to increase the resin fluidity during injection molding when creating the operation panel. For this reason, if the thickness of the operation panel is too thick, there is a risk that the sensitivity of the capacitance sensor will be reduced, or that the operation may not be detected even when the operation body is closest to the electrostatic pad. There is.

  Note that by increasing the area of the electrode pad, it is possible to detect the operating tool even when the operation panel is thick. However, there is of course an upper limit on the area of the electrode pad due to space design restrictions.

  As described above, in the conventional technology, when the thickness of the operation panel made of resin or the like formed on the electrostatic capacitance sensor constituted by the transparent conductive film or the like must be thicker than a predetermined value, There is a possibility that the approach or contact of an operating body such as a fingertip of a human body cannot be reliably detected due to a decrease in sensitivity.

  The present invention has been made to solve the above-described problems, and the thickness of an operation panel made of a resin or the like formed on a capacitance sensor made of a transparent conductive film or the like must be made larger than a predetermined value. It is an object of the present invention to provide a capacitive touch panel capable of reliably detecting the approach or contact of an operating body such as a fingertip of a human body even when the touch is not obtained.

In order to achieve the above object, the invention according to claim 1 of the present application provides an electrostatic pad having an electrode pad for detecting the approach or contact of the operating body by performing electrostatic coupling with the operating body approaching. A capacitance sensor;
In the capacitance type touch panel provided with the operation panel provided on the back surface with the capacitance sensor,
A concave portion having a thickness smaller than that of the other region is provided in a part of the surface of the operation panel opposite to the region where the capacitance sensor is provided, and the surface of the resin material is deposited in the concave portion by vapor deposition. The contact portion on which the metal film is formed is embedded.

  In the present invention, the contact portion in which a metal film is formed on the surface of the resin material by vapor deposition is embedded in a recess provided in the operation panel, and the distance between the contact portion and the electrode pad is the recess of the operation panel. It is shorter than the thickness of the other region. Therefore, when an operating body such as a human fingertip comes into contact with the contact portion, the operating body is electrostatically coupled to the electrode pad through the contact portion at a distance shorter than the thickness of the operation panel. As a result, according to the present invention, even when the thickness of the operation panel is inevitably larger than a predetermined value, it is possible to reliably detect the approach or contact of the operation body such as a human finger.

  In the invention according to claim 2 of the present application, the region where the electrode pad of the capacitance sensor is not provided on the reverse side of the surface region of the operation panel is thinner than the other regions. A second recess is provided, and in the second recess, a metal film is formed on the surface of the resin material by vapor deposition, and a decorative portion electrically connected to the ground potential is embedded.

  According to the present invention, even when electrostatic discharge noise is applied to the operation panel, the electrostatic noise is discharged via the decorative portion electrically connected to the ground potential. It is possible to prevent the occurrence of a situation in which electrostatic discharge noise jumps into the electronic circuit and destroys an electronic circuit such as a control unit.

  In the invention according to claim 3 of the present application, the contact portion has a permittivity and conductivity such that a change in capacitance does not exceed a detection threshold when the operating body is not approaching or in contact. Further, the film thickness of the metal film formed on the surface of the resin material is set.

  According to the present invention, even though the operating body is not approaching or in contact with the contact portion, the capacitance change exceeds the detection threshold due to electrostatic coupling between the electrode pad and the contact portion, so that the malfunction occurs. It is possible to prevent the occurrence of a serious situation.

  Furthermore, in the invention which concerns on Claim 4 of this application, the said contact part forms the metal film on the surface of the resin material by the discontinuous vapor deposition which does not produce electrical continuity in the metal film formed.

  According to the present invention, even when the thickness of an operation panel made of a resin or the like formed on a capacitance sensor made of a transparent conductive film or the like has to be thicker than a predetermined value, The effect that it becomes possible to reliably detect the approach or contact of the operating body can be obtained.

It is the general-view figure which looked at the general capacitive touch panel before applying the present invention from the operation side. It is a figure which shows only the electrostatic capacitance sensor comprised by electrode pad 20a-20d and wiring electrode 30a-30d. FIG. 2 is a cross-sectional view taken along the line AA ′ of the general capacitive touch panel shown in FIG. 1 (when the thickness of the operation panel 110 is d1). FIG. 2 is a cross-sectional view taken along the line AA ′ of the general capacitive touch panel shown in FIG. 1 (when the thickness of the operation panel 110 is d2). It is the general-view figure which looked at the capacitive touch panel of one embodiment of the present invention from the operation side. It is BB 'sectional drawing in the capacitive touch panel of this embodiment shown in FIG. It is a figure for demonstrating the structure of the touch part 80c shown in FIG. It is a figure for demonstrating the process of manufacturing the electrostatic capacitance type touch panel of one Embodiment of this invention.

  Next, the capacitive touch panel of the present embodiment will be described, but before that, the configuration of a general capacitive touch panel before applying the present invention will be described.

  FIG. 1 is an overview of this general capacitive touch panel as viewed from the operation surface side.

  As shown in FIG. 1, this general capacitive touch panel is configured as a part of a front panel of an automobile such as a passenger car, for example, and includes an operation panel 110 and a static panel provided on the back surface of the operation panel 110. It is composed of a capacitance sensor. The operation panel 110 is made of a resin material such as polycarbonate or acrylic, and is formed as a dielectric layer having a relative dielectric constant of about 3. The capacitance sensor is formed on an adhesive film (not shown) and is formed of a transparent conductive film such as ITO (Indium Tin Oxide), and the electrode pads 20a to 20d. It is comprised by wiring electrode 30a-30d for each transmitting the change of the electrostatic capacitance of -20d.

  The electrode pads 20a to 20d are respectively arranged corresponding to the characters printed on the operation panel 110, and when an operation body such as a fingertip of a human body approaches the printed character, It is provided to detect the approach or contact of the operating body by performing electrostatic coupling between them.

  The four wiring electrodes 30a to 30d are connected to the connector 40, and are connected to the connector 60 on the control board by a cable 50 such as FFC (Flexible Flat Cable).

  Therefore, the control unit 70 provided on the control board can monitor the capacitance values of the electrode pads 20a to 20d, and the amount of change in the capacitance value is detected in advance. When the threshold value is exceeded, it is determined that the operating body has approached or contacted the electrode pad.

  The electrostatic capacitance sensor comprised by electrode pad 20a-20d and wiring electrode 30a-30d is affixed on the back surface of the operation panel 10 with the adhesive film, for example. Only the electrostatic capacitance sensor constituted by the electrode pads 20a to 20d and the wiring electrodes 30a to 30d is shown in FIG.

  Each of the four electrode pads 20a to 20d is arranged at a position corresponding to the printed character on the operation panel 110 as described above. The wiring electrodes 30a to 30d electrically connect the four electrode pads 20a to 20d and the connector 40, respectively.

  Next, AA ′ cross-sectional views of the general capacitive touch panel shown in FIG. 1 are shown in FIGS. 3 and 4.

  3 is a cross-sectional view when the thickness of the operation panel 110 is reduced to, for example, about 2 to 2.5 mm (d1). FIG. 4 is a cross-sectional view of the operation panel 110, for example, to about 3 to 4 mm (d2). It is sectional drawing at the time of making it thick.

  As shown in FIGS. 3 and 4, the electrode pad 20 c and the wiring electrodes 30 a and 30 b are attached to the back surface of the operation panel 110 with an adhesive film 23. The electrode pad 20 c is disposed at a position corresponding to the print character 21 printed on the surface of the operation panel 110. When an operation body such as a fingertip of a human body approaches or contacts the vicinity of the printed character 21 on the operation panel 110, a capacitor is formed by electrostatic coupling between the operation body and the electrode pad 20c, and the capacitance of the electrode pad 20c is increased. Change. When the control unit 70 detects this change in capacitance, it is determined that the operation is performed by the operating tool.

  3 is compared with FIG. 4, the thickness of the operation panel 110 in FIG. 4 is d2, which is significantly greater than the thickness d1 of the operation panel 110 in FIG. Therefore, in the configuration as shown in FIG. 3, even when the approach or contact of the operating body can be detected, the sensitivity as shown in FIG. Or contact may not be detected.

[Embodiment]
Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 5 shows an overview of the capacitive touch panel of one embodiment of the present invention as viewed from the operation surface side.

  The capacitive touch panel of the present embodiment has a configuration in which the operation panel 10 is replaced with an operation panel 110 with respect to the general capacitive touch panel before the present invention shown in FIG. 1 is applied. . The operation panel 10 in the capacitive touch panel according to the present embodiment has a touch portion (contact portion) close to four printed characters, compared to the operation panel 110 in the general capacitive touch panel shown in FIG. The difference is that 80a to 80d are provided, and an accent part 81 is provided adjacent to the side of the four touch parts 80a to 80d. Since other configurations are the same as those in the general capacitive touch panel shown in FIG. 1, the same reference numerals are given and detailed descriptions thereof are omitted.

  Next, FIG. 6 shows a BB ′ cross-sectional view of the capacitive touch panel of this embodiment shown in FIG.

  The thickness of the operation panel 10 in the present embodiment is the same as the thickness of the conventional operation panel 110 shown in FIG. 4, that is, d2, for reasons such as ensuring strength and resin fluidity during injection molding. It is thick.

  In the operation panel 10 according to the present embodiment, as shown in FIG. 6, a recess having a smaller thickness than other regions is provided in a part of the surface region opposite to the region where the capacitance sensor is provided. The touch portion (contact portion) 80c is embedded in the recess.

  In this recess, the thickness of the operation panel 110 is d1, which is thinner than the thickness d2 in other regions. Therefore, the distance between the lower surface of the touch part 80c and the electrode pad 20c is also a distance d1.

  In the present embodiment, a concave portion (second concave portion) having a smaller thickness than other regions is formed in a region where the electrode pad of the capacitance sensor is not provided on the reverse side of the front surface region of the operation panel 10. ) And an accent part (decoration part) 81 is embedded in the recess. The accent portion 81 is electrically connected to the ground potential by being connected to the body chassis 100 of the automobile by an electric wire.

  The touch portions 80a to 80d and the accent portion 81 have a thickness of, for example, about 3 mm, and are both formed by forming a metal film on the surface of the resin material by vacuum deposition.

  The structure of the touch part 80c will be described with reference to FIG. Here, only the structure of the touch part 80c will be described, but the structures of the other touch parts 80a, 80b, 80d and the accent part 81 are the same as the structure of the touch part 80c.

  As shown in FIG. 7, the touch portion 80c is formed by forming a metal material such as aluminum or indium as a surface metal film 92 by vacuum deposition on the surface of a resin material 91 such as polycarbonate or ABS (Acrylonitrile Butadiene Styrene) resin. It has a structure. The film thickness of the surface metal film 92 is 1 μm or less, and is a thin film thickness in units of ridges.

  More specifically, in the touch part 80c, the surface metal film 92 is formed on the surface of the resin material 91 by discontinuous vapor deposition in which electrical conductivity is not generated in the formed metal film.

  Here, discontinuous vapor deposition (non-conductive vapor deposition) is a type of vacuum vapor deposition in which a metal material is vapor-deposited with such a thickness that metal molecules do not conduct on the surface of a resin or the like. Since the metal film formed by this discontinuous deposition does not have electrical continuity, it is used for depositing a metal material on products or parts that do not want to be electrically conducted.

  In addition, it is also possible to form a surface metal film on the surfaces of the touch portions 80a to 80d and the accent portion 81 by other methods such as sputtering.

  In the capacitive touch panel of this embodiment, the surface metal film 92 formed on the surfaces of the touch parts 80a to 80d and the accent part 81 is formed by discontinuous vapor deposition because the surface metal film 92 is completely formed. This is because, if the electrical conductivity is high, malfunction occurs due to electrostatic coupling between the electrode pads 20a to 20d. That is, there is a case where the presence of the touch parts 80a to 80d is erroneously detected as the approach of the operating body even though the operating body does not actually exist.

  For this reason, in the present embodiment, the surface metal film 92 formed on the surfaces of the touch portions 80a to 80d and the accent portion 81 is not electrically conductive so as to prevent malfunction.

  And when manufacturing the capacitive touch panel of this embodiment, the operation panel 10, the touch parts 80a to 80d, and the accent part 81 are created by different processes, respectively, and as shown in FIG. The capacitive touch panel is manufactured by embedding the touch part 80c and the accent part 81 in the recessed parts 24 and 25 provided.

  In the capacitive touch panel of the present embodiment, as shown in FIG. 6, the distance between the touch part 80c embedded in the recess 24 provided in the operation panel 10 and the electrode pad 20c is, for example, 2 The d1 is about 2.5 mm. When an operating body such as a human fingertip approaches or comes into contact with the touch unit 80c, the operating body performs electrostatic coupling with the electrode pad 20c via the touch unit 80c.

  That is, in this embodiment, although the thickness of the entire operation panel 10 is as thick as d2 of about 3 to 4 mm, the operation body has a thickness of the operation panel between the electrode pad 20c and the touch part 80c. The electrostatic coupling is performed by a distance d1 shorter than d2. More specifically, the touch unit 80c has a function of performing a bridge for transmitting the contact of the operating body to the electrode pad 20c. As a result, in the capacitive touch panel according to the present embodiment, even when the thickness of the operation panel has to be thicker than a predetermined value, the approach or contact of the operation body such as the fingertip of the human body can be reliably detected. Is possible.

  In the capacitive touch panel according to the present embodiment, the touch units 80a to 80d are configured such that the change in the capacitance causes the detection threshold in the control unit 70 to be detected when an operating body such as a human fingertip is not approaching or touching. The film thickness of the surface metal film 92 formed on the surface of the resin material 91 is set so as to have a dielectric constant and conductivity that do not exceed.

  This is because if the thickness of the surface metal film 92 is excessively increased and the conductivity of the touch portions 80a to 80d is increased, the operation is performed even though the operating body is not approaching. If a malfunction occurs and the surface metal film 92 is made too thin to be a mere resin material, it becomes a part of the resin material constituting the operation panel 10 and simply increases the thickness of the operation panel 10. Because it will end up.

  The inventor of the present application adjusts the film thickness of the surface metal film 92 so that when the operating body does not exist, the change in capacitance does not exceed the detection threshold, and the operating body approaches this. We have succeeded in achieving an optimal film thickness that can be reliably detected.

  Therefore, in the capacitive touch panel of this embodiment, by setting the film thicknesses of the touch portions 80a to 80d and the accent portion 81 to such optimum thicknesses, no malfunction occurs, and the operation body approaches or It becomes possible to detect contact reliably.

  Furthermore, according to the capacitive touch panel of this embodiment, even when ESD (Electro Static Discharge) noise or the like is applied to the operation panel 10, the ESD noise is electrically connected to the ground potential. It is discharged via the accent part 81. For example, ESD noise applied to the touch part 80 c is discharged via the accent part 81 and the body chassis 100. Therefore, according to the capacitive touch panel of the present embodiment, the accent portion 81 plays a role like a lightning rod, so that ESD noise is generated in the electrode pads 20a to 20d and the wiring electrodes 30a to 30d of the capacitance sensor. It is possible to prevent the occurrence of a situation where the electronic circuit such as the control unit 70 jumps in and breaks down.

[Modification]
In the above embodiment, the case where the present invention is applied to a capacitive touch panel provided as a part of a front panel of an automobile such as a passenger car has been described. However, the present invention is not limited to this, The present invention can be similarly applied to all electronic devices that detect an operating body using a capacitance sensor.

  In the above embodiment, the case where four switches are configured on the operation panel 10 will be described. However, the present invention is not limited to such a configuration, and the number of switches is larger than this. However, it can be similarly applied even when the number is small.

DESCRIPTION OF SYMBOLS 10 Operation panel 20a-20d Electrode pad 21 Print character 23 Adhesive film 24, 25 Recessed part 30a-30d Wiring electrode 40 Connector 50 Cable 60 Connector 70 Control part 80a-80d Touch part 81 Accent part 91 Resin material 92 Surface metal film 100 Body Chassis 110 Operation panel

Claims (4)

A capacitive sensor having an electrode pad for detecting the approach or contact of the operating body by performing electrostatic coupling with the approaching operating body;
In the capacitance type touch panel provided with the operation panel provided on the back surface with the capacitance sensor,
A concave portion having a thickness smaller than that of the other region is provided in a part of the surface of the operation panel opposite to the region where the capacitance sensor is provided, and the surface of the resin material is deposited in the concave portion by vapor deposition. A capacitive touch panel in which a contact portion on which a metal film is formed is embedded.   A second recess having a thickness smaller than that of the other region is provided in a region where the electrode pad of the capacitance sensor is not provided on the reverse side of the front surface region of the operation panel. The capacitive touch panel according to claim 1, wherein a metal film is formed on the surface of the resin material by vapor deposition in the recess, and a decorative part electrically connected to the ground potential is embedded.   The contact portion is a metal film formed on the surface of the resin material so that a change in capacitance does not exceed a detection threshold when the operating body is not approaching or in contact with the operation body. The capacitive touch panel according to claim 1, wherein the film thickness is set.   The capacitive touch panel according to claim 3, wherein the contact portion has a metal film formed on the surface of the resin material by discontinuous vapor deposition that does not cause electrical conductivity in the formed metal film.

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