JP2015222456A - Capacitance sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a capacitance sensor which offers a uniform transmittance and improved yield and productivity.SOLUTION: A capacitance sensor is for detecting a position of an approaching target object based on changes in capacitance of a plurality of conductive sections 112a, and is configured with a single functional film 112, having the plurality of conductive sections 112a and insulating sections 112b that insulate each of the plurality of conductive sections from others, formed on a principal surface 111a on one side of a substrate 111. Since the plurality of conductive sections and insulating sections that insulate between each of the plurality of conductive sections are achieved on a single functional film in this configuration, significant reduction in transmittance of some conductive sections relative to others can be avoided, realizing a uniform transmittance thereby. Also, the configuration does not cause a step, or level difference, at edge portions of each conductive section, which prevents peeling at the edge portions and improves yield and productivity.

Description

  The present invention relates to a capacitance type sensor that detects the position of an object to be detected based on a change in capacitance of an electrode.

  There has been proposed a capacitive sensor that two-dimensionally detects a proximity position of an object to be detected such as a fingertip based on a change in electrostatic capacitance of an electrode (see, for example, Patent Document 1). This capacitive sensor includes a first electrode arranged in the first axial direction and a second electrode that is insulated from and intersects the first electrode. When the object to be detected comes close to the first electrode and the second electrode, the capacitance changes. Therefore, by detecting the set of the first electrode and the second electrode whose capacitance has changed, The proximity position can be specified.

JP-A-3-289715

  By the way, the capacitance type sensor may be required to have a certain degree of translucency so that it can be used in a state of being overlapped with a display device such as a liquid crystal panel. For this reason, a transparent electrode obtained by patterning a transparent conductive film such as ITO (indium tin oxide) by etching is used for the capacitance type sensor.

  However, the portion where the conductive film of the transparent electrode patterned in this way has a lower transmittance than the portion where the conductive film is removed, so that the visibility of the display device used in a superimposed manner is lowered. May interfere with text input and screen operations. Further, peeling may occur from the edge portion of the transparent electrode formed by pattern processing, which may reduce the yield and productivity of the capacitive sensor.

  The present invention has been made in view of such points, and an object of the present invention is to provide a capacitive sensor capable of achieving uniform transmittance and improving yield and productivity.

  The capacitance type sensor of the present invention is a capacitance type sensor that detects a proximity position of a detection object based on a change in capacitance of a plurality of conductive portions, and the plurality of the plurality of the capacitance type sensors on one main surface of a substrate. A single functional film having a conductive portion and an insulating portion that insulates the plurality of conductive portions from each other is provided.

  According to this configuration, since the plurality of conductive portions and the insulating portion that insulates the plurality of conductive portions from each other are realized by a single functional film, the transmittance of the conductive portions is compared with other portions. There is no significant decrease, and a uniform transmittance can be realized. Further, since no step is generated at the edge portion of the conductive portion, peeling from the edge portion can be prevented, and yield and productivity can be improved. Further, even when the sensor is made of a flexible material, peeling due to deformation can be prevented.

  In the capacitive sensor of the present invention, the functional film may contain PEDOT (polyethylenedioxythiophene). According to this configuration, the plurality of conductive portions and the insulating portion that insulates the plurality of conductive portions from each other can be appropriately formed with a single functional film.

  In the capacitive sensor of the present invention, the substrate may have a curved surface shape together with the functional film. According to this configuration, since the substrate has a curved surface shape, a device with improved operational feeling and design can be realized. In addition, since the plurality of conductive portions and the insulating portion that insulates the plurality of conductive portions from each other are realized by a single functional film, even if the substrate is curved into a curved surface shape, Peeling can be prevented.

  According to the present invention, it is possible to provide a capacitive sensor capable of realizing uniform transmittance and improving yield and productivity.

It is a schematic diagram which shows the external shape of the electrostatic capacitance type sensor which concerns on this Embodiment. It is a plane schematic diagram which shows the electrode structure of the electrostatic capacitance type sensor which concerns on this Embodiment. It is a circuit block diagram of the capacitive sensor according to the present embodiment. It is a figure which shows the manufacturing method of the electrostatic capacitance type sensor which concerns on this Embodiment. 4A and 4B show a substrate used for manufacturing a capacitive sensor, FIGS. 4C and 4D show a state in which a functional film is formed on the substrate, and FIGS. 4E and 4F show conductive portions and A mode that the insulation part was formed is shown. It is a figure which shows the manufacturing method of the electrostatic capacitance type sensor which concerns on this Embodiment. 5A and 5B show a state in which a routing wiring is formed, and FIG. 5C shows a state in which a decoration pattern is added to the substrate.

  Hereinafter, a configuration of a capacitive sensor according to an embodiment of the present invention will be described with reference to the accompanying drawings. In the present embodiment, a simplified capacitive sensor will be described for convenience of explanation, but the configuration necessary for the capacitive sensor is provided without a shortage. Moreover, in each figure, transparent structures, such as an electrode, may be expressed opaquely.

  FIG. 1 is a schematic diagram illustrating an outer shape of a capacitive sensor according to the present embodiment, and FIG. 2 is a schematic plan view illustrating an electrode configuration of the capacitive sensor according to the present embodiment. FIG. 3 is a circuit block diagram of the capacitive sensor according to the present embodiment. As shown in FIG. 1, the capacitive sensor 1 includes a sensor main body 11 and a flexible printed circuit board 12 connected to the outer periphery of the sensor main body 11.

  As shown in FIGS. 1 and 2, the sensor main body 11 includes a substrate 111 that forms the outer shape of the sensor main body 11. The substrate 111 is formed of a light-transmitting resin and is curved into a curved surface shape (FIG. 1). A plurality of conductive portions 112a functioning as detection electrodes of the capacitive sensor 1 are arranged in a stripe pattern on one main surface (a surface on the back side of the substrate 111 in FIG. 1) 111a of the substrate 111.

  The plurality of conductive portions 112a are all formed so that the planar shape is substantially rectangular, and are arranged substantially parallel to each other so that the interval between the adjacent conductive portions 112a is constant. Each conductive part 112a has conductivity and is insulated from each other by an insulating part 112b. In addition, the conductive portion 112a and the insulating portion 112b have a light-transmitting property so that a display of a display device (not shown) that is used in an overlapping manner with the capacitive sensor 1 can be visually recognized. When a detected object (not shown) such as a fingertip comes close to the conductive portion 112a, the capacitance of the conductive portion 112a changes. By utilizing this, the proximity position of the detection target can be specified.

  In the capacitive sensor 1 of the present embodiment, the plurality of conductive portions 112a and insulating portions 112b are configured by a single functional film 112. As described above, by realizing the plurality of conductive portions 112a serving as the electrodes of the capacitive sensor 1 and the insulating portion 112b that insulates the plurality of conductive portions 112a from each other by the single functional film 112, the conductive portion A step does not occur in the edge portion of 112a. For this reason, unlike the case of pattern processing by etching, the transmittance of the conductive portion 112a is not significantly reduced, and peeling from the edge portion of the conductive portion 112a can be prevented.

  The functional film 112 is formed using, for example, a conductive transparent resin such as PEDOT (polyethylenedioxythiophene). PEDOT has a feature that it is insulated when it is overoxidized. Therefore, by partially peroxidizing the functional film 112 containing PEDOT, the conductive portion 112a and the insulating portion 112b can be separately formed without using a method such as etching.

  One end of the routing wiring 114 is connected to both ends of each conductive portion 112a. The other end of the routing wiring 114 is connected to a wiring (not shown) provided on the flexible printed circuit board 12. The flexible printed circuit board 12 is equipped with a detection IC 13 for detecting a change in the capacitance of the conductive portion 112a and a microprocessor 14 for processing a detection signal output from the detection IC 13.

  As shown in FIG. 3, the change in the capacitance of the conductive portion 112 a is detected as an electrical signal by the detection IC 13. The detection result of the detection IC 13 is input to the microprocessor 14 for signal processing. The signal processed by the microprocessor 14 is input to the external device 2 at the subsequent stage.

  When a detection object such as a fingertip comes close to the sensor main body 11 of the capacitance type sensor 1, the capacitance of the conductive portion 112a changes. The change in capacitance is greatest at the conductive portion 112a closest to the detection target in the arrangement direction of the conductive portions 112a (the direction perpendicular to the longitudinal direction of the conductive portions 112a). For this reason, the change of the electrostatic capacitance of the plurality of conductive parts 112a is detected by the detection IC 13 and compared by the microprocessor 14, whereby the position of the detected object in the arrangement direction of the conductive parts 112a can be specified. For example, when the detected object is positioned between two adjacent conductive parts 112a, the position of the detected object can be specified from the ratio of the change in capacitance of the two adjacent conductive parts 112a.

  On the other hand, the position of the detection object in the longitudinal direction of the conductive portion 112a is specified using the electrical resistance of the conductive portion 112a. Lead wires 114 are connected to both ends of the conductive portion 112a, respectively, and the capacitance of the conductive portion 112a can be detected from both ends. Since the conductive portion 112a has a predetermined electric resistance, the ratio of the detection amounts detected at both ends of the conductive portion 112a varies depending on the position of the detection target. For this reason, the position of the detected object can be specified based on the ratio of the detection amounts detected at both ends of the conductive portion 112a. The signal including the position information of the detection object output from the microprocessor 14 is arbitrarily used in the external device 2 at the subsequent stage.

  With reference to FIG.4 and FIG.5, the manufacturing method of the electrostatic capacitance type sensor 1 which concerns on this Embodiment is demonstrated. 4A is a schematic plan view showing a substrate 111 used for manufacturing the capacitive sensor 1, and FIG. 4B is a cross-sectional view taken along the line IVB-IVB in FIG. 4A. As shown in FIGS. 4A and 4B, in the method of manufacturing a capacitive sensor according to the present embodiment, first, a substrate 111 that constitutes the outer shape of the sensor body 11 is prepared. The substrate 111 is made of a light-transmitting resin such as PET, acrylic, or polycarbonate, and can be bent into a curved surface.

  A functional film 112 serving as the conductive portion 112a and the insulating portion 112b is formed on the one-side main surface 111a of the substrate 111. 4C is a schematic plan view showing a state in which the functional film 112 is formed on the substrate 111, and FIG. 4D is a cross-sectional view taken along the line IVD-IVD in FIG. 4C. The functional film 112 is formed, for example, by applying an aqueous solution of PEDOT / PSS (polyethylenedioxythiophene / polystyrene sulfonic acid). The functional film 112 containing PEDOT thus formed has both conductivity and translucency.

Here, PEDOT contained in the functional film 112 is represented by the following formula (1).

When this PEDOT is peroxidized, a ring-opening reaction of a thiophene ring as shown in the following formula (2) occurs to be insulated. For this reason, the functional film 112 can be insulated by peroxidizing the functional film 112 containing PEDOT.

  4E is a schematic plan view showing a state in which the conductive portion 112a and the insulating portion 112b are formed, and FIG. 4F is a cross-sectional view taken along the arrow IVF-IVF in FIG. 4E. After the functional film 112 is formed on the one-side main surface 111a of the substrate 111, a desired region of the functional film 112 is selectively peroxidized by, for example, a mask arrangement to form a plurality of conductive portions 112a and insulating portions 112b. . As a result, the substrate 111 is in a state in which the single functional layer 112 having the plurality of conductive portions 112a and the insulating portions 112b is provided on the one-side main surface 111a.

  Next, the routing wiring 114 connected to the conductive portion 112a is formed. 5A is a schematic plan view showing a state in which the routing wiring 114 is formed, and FIG. 5B is a cross-sectional view taken along the arrow VB-VB in FIG. 5A. The routing wiring 114 is formed by a method such as screen printing or vapor deposition using a conductive material such as gold, silver, copper, aluminum, molybdenum, or carbon. Further, the routing wiring 114 is formed so that one end thereof is in contact with the conductive portion 112a and most of the remaining portion overlaps the insulating portion 112b.

  Each conductive portion 112a is provided with two routing wirings 114 corresponding to both ends in the longitudinal direction of the conductive portion 112a. The two routing wirings 114 connected to both ends of each conductive portion 112a are formed so as to be substantially symmetric with respect to a straight line connecting the centers in the longitudinal direction of the plurality of conductive portions 112a. That is, the two routing wirings 114 are formed so as to be substantially line symmetrical with each other. As a result, the impedances of the two routing wires 114 connected to the single conductive portion 112a are substantially equal, and the capacitance can be detected from the both ends of the single conductive portion 112a under the same conditions. Even if the routing wiring 114 is asymmetric, by providing a difference in the conductivity of the conductive portion 112a and the routing wiring 114, the influence of the asymmetry when detecting the capacitance can be reduced.

  Thereafter, the region of the substrate 111 where the routing wiring 114 is formed is decorated. FIG. 5C is a schematic plan view showing a state in which the decoration pattern 115 is added to the substrate 111. In this step, the decoration pattern 115 is formed on the substrate 111 by a method such as screen printing. The routing pattern 114 formed on the substrate 111 is obscured by the decoration pattern 115. Thus, the processing of the surface of the substrate 111 is completed.

  When the processing of the surface of the substrate 111 is completed, the outer shape of the substrate 111 is then deformed by a method such as insert molding. Thereby, the sensor body 11 having an outer shape curved in a curved surface shape is realized (see FIG. 1). Each component such as the functional film 112 and the routing wiring 114 is curved together with the substrate 111.

  After the outer shape of the sensor main body 11 is formed, the flexible printed circuit board 12 is connected to the sensor main body 11 through HC coating or outer shape processing (see FIG. 1). Through the above steps, the capacitive sensor 1 including the single functional film 112 having the plurality of conductive portions 112a and the insulating portions 112b is manufactured.

  In the capacitive sensor 1 according to the present embodiment, the plurality of conductive portions 112a and the insulating portion 112b that insulates the plurality of conductive portions 112a from each other are realized by a single functional film 112. The transmittance of the portion 112a is not significantly reduced as compared with other portions, and a uniform transmittance can be realized. As a result, the visibility of the display device that is used in an overlapping manner can be improved. In addition, since no step is generated in the edge portion of the conductive portion 112a, peeling from the edge portion can be prevented and yield and productivity can be improved.

  Further, in the capacitance type sensor 1 according to the present embodiment, the functional film 112 includes PEDOT (polyethylenedioxythiophene), so that the plurality of conductive portions 112a and the plurality of conductive portions 112a are insulated from each other. The insulating portion 112b to be formed can be appropriately formed by the single functional film 112.

  Further, in the capacitive sensor 1 according to the present embodiment, since the substrate 111 has a curved surface shape together with the functional film 112, a device with improved operational feeling and design can be realized. In addition, since the plurality of conductive portions 112a and the insulating portion 112b that insulates the plurality of conductive portions 112a from each other are realized by a single functional film 112, even if the substrate 111 is curved into a curved shape, the conductive portions Peeling from the edge portion of 112a can be prevented.

  In addition, this invention is not limited to description of the said embodiment, It can implement by changing suitably in the aspect in which the effect is exhibited. For example, in the above-described embodiment, the capacitive sensor in which the conductive portions are arranged in a stripe shape is shown, but the configuration of the conductive portions is not particularly limited. For example, two layers of functional films may be provided so as to sandwich an insulating film therebetween, and the longitudinal directions of the conductive portions formed in the respective functional films may be crossed.

  Moreover, in the said embodiment, although the electrostatic capacitance type sensor which has the curved external shape is shown, the electrostatic capacitance type sensor may have a flat external shape. In this case, the step of deforming the outer shape of the substrate is not necessary. In the above embodiment, the capacitance type sensor in which the detection IC and the microprocessor are mounted on the flexible printed board is shown. However, the detection IC and the microprocessor may be mounted on the sensor body. Alternatively, it may be provided outside the capacitive sensor.

  The capacitive sensor of the present invention is useful as an input device that performs various inputs based on the contact position of a fingertip, for example.

DESCRIPTION OF SYMBOLS 1 Capacitance type sensor 2 External device 11 Sensor main body 12 Flexible printed circuit board 13 IC for detection
14 Microprocessor 111 Substrate 111a Main surface 112 on one side 112 Functional film 112a Conductive portion 112b Insulating portion 114 Wiring wiring 115 Decorating pattern

Claims (3)

A capacitance type sensor that detects a proximity position of a detection object based on a change in capacitance of a plurality of conductive parts,
A capacitance type sensor comprising a single functional film having a plurality of conductive portions and an insulating portion that insulates the plurality of conductive portions from each other on one main surface of a substrate.   The capacitive sensor according to claim 1, wherein the functional film includes PEDOT (polyethylenedioxythiophene).   The capacitive sensor according to claim 1, wherein the substrate has a curved surface shape together with the functional film.

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