Antenna unit

Abstract

An antenna unit (1A) comprises: a first electrode (11); a second electrode 12 that is positioned in a first direction (D1) from the first electrode (11) and is adjacent to the first electrode (11); and a first excitation element (21) that is provided on an upper layer of the first electrode (11) and the second electrode (12), and extends in the first direction (D1). The first excitation element (21) has a first end (21a) and a second end (21b). When a wavelength obtained in consideration of wavelength shortening is set as λg at a frequency to which the first excitation element (21) corresponds, the length between the first end (21a) and the second end (21b) of the first excitation element (21) is 11 λg / 80 or less.

Description

Antenna unit

[0001] The present disclosure relates to an antenna unit.

[0002] Conventionally, as an antenna unit that combines an electrode constituting a touch sensor or the like and an antenna, for example, the one disclosed in Patent Document 1 is known.

[0003] Specifically, Patent Document 1 discloses an antenna unit (touch sensor panel 10) including a film-shaped substrate 20, a touch sensor unit 12 provided on the substrate 20, and an antenna 16 provided on the substrate 20. The touch sensor unit 12 has a sensor unit 18a. The sensor unit 18a includes a first conductive layer 30 and a second conductive layer 40. The antenna 16 is arranged so as to be orthogonal to the first conductive layer 30 or the second conductive layer 40. In a top view, the antenna 16 overlaps with the first conductive layer 30 (or the second conductive layer 40) orthogonal to the antenna 16.

[0004] The antenna 16 is configured as a monopole antenna. The length of the antenna 16 is appropriately determined according to the wavelength of the radio wave to be used. As the length of the antenna 16 disclosed in Patent Document 1, for example, it is 3 cm at a frequency of 2.4 GHz.

[0005] Japanese Unexamined Patent Application Publication No. 2016-219999

[0006] As described above, in the antenna unit of Patent Document 1, the antenna 16 and the first conductive layer 30 (or second conductive layer 40) perpendicular to the antenna 16 overlap when viewed from above. In this configuration, capacitive coupling may occur between the antenna 16 and the first conductive layer 30 (or second conductive layer 40). When such capacitive coupling occurs, current is generated in the first conductive layer 30 (or second conductive layer 40) that overlaps with the antenna 16 when viewed from above, and the first conductive layer 30 (or second conductive layer 40) functions as part of the antenna 16. As a result, resonance occurs in a frequency band lower than the desired frequency corresponding to the length of the antenna 16 (for example, a frequency of 2.4 GHz). In other words, in the antenna unit of Patent Document 1, it was sometimes not possible to appropriately match the radio waves radiated from the antenna 16 to a predetermined frequency.

[0007] Furthermore, when actually using the antenna unit described in Patent Document 1, wavelength shortening occurs in the radio waves radiated from the antenna 16 due to various components (relative permittivity of these components) located around the antenna 16. Taking this wavelength shortening into consideration, it is necessary to appropriately determine the length of the antenna 16 in order to appropriately correspond the radio waves radiated from the antenna 16 to a predetermined frequency.

[0008] This disclosure has been made in view of the above, and its purpose is to appropriately match the radio waves radiated from the antenna to a predetermined frequency.

[0009] To achieve the above objective, one embodiment of the present disclosure is an antenna unit comprising: a first electrode; a second electrode located in a first direction from the first electrode and adjacent to the first electrode; and a first excitation element provided on the upper layer between the first electrode and the second electrode and extending in a first direction. The first excitation element has a first end located in the direction opposite to the first direction from the first electrode, and a second end located in the first direction from the first end. When the wavelength considering wavelength shortening is λg at the corresponding frequency of the first excitation element, the length between the first end and the second end of the first excitation element is 11λg / 80 or less.

[0010] According to this disclosure, the radio waves radiated from the first excitation element can be appropriately matched to a predetermined frequency.

[0011] Figure 1 is a plan view of the antenna unit according to the first embodiment of this disclosure. Figure 2 is a schematic cross-sectional view taken along line II-II in Figure 1. Figure 3 is a schematic cross-sectional view taken along line II-II in Figure 1. Figure 4 is a partially enlarged view of section IV. Figure 5 is a graph relating to the curve Cv, with the horizontal axis representing the length of the first excitation element (unit: mm) and the vertical axis representing the resonant frequency (center frequency, unit: GHz). Figure 6 is a plan view of the antenna unit according to the second embodiment of this disclosure. Figure 7 is a schematic cross-sectional view taken along line VII-VII in Figure 6. Figure 8 is a schematic cross-sectional view taken along line VIII-VIII in Figure 6.

[0012] [First Embodiment] Figure 1 is a plan view of an antenna unit 1A according to the first embodiment. As shown in Figure 1, the antenna unit 1A according to the present disclosure comprises a substrate 2, a sensor unit 10A, and an excitation unit 20.

[0013] In the following explanation, the direction from the left side of Figure 1 to the right side of the page (direction D1 shown in the figure) is defined as the "first direction." The direction from the bottom of Figure 1 to the top of the page (direction D2 shown in the figure) is defined as the "second direction."

[0014] Furthermore, in the first embodiment, the side where the first substrate 3 (described later) shown in Figures 2 and 3 is located is defined as the "lower side" of the antenna unit 1A, and the side where the second substrate 4 (described later) is located is defined as the "upper side" of the antenna unit 1A, thereby defining the positional relationship of each element constituting the antenna unit 1A. Note that such positional relationships are unrelated to the actual vertical direction of the equipment or device on which the antenna unit 1A is mounted.

[0015] (Substrate) As shown in Figure 1, the substrate 2 is formed in a substantially rectangular shape when viewed from above, for example. The substrate 2 is transparent and insulating. Preferably, the substrate 2 is flexible.

[0016] As shown in Figures 2 and 3, the substrate 2 includes a first substrate 3 and a second substrate 4. The first substrate 3 and the second substrate 4 are formed in the form of a film.

[0017] The first substrate 3 is formed from a resin material that is transparent and insulating.

[0018] The second substrate 4 is laminated on top of the first substrate 3 via an adhesive layer 5. The second substrate 4 is made of a resin material that is transparent and insulating. The second substrate 4 may be made of the same resin material as the first substrate 3, or it may be made of a different resin material.

[0019] (Sensor section) The sensor section 10A illustrated in this embodiment is a mutual capacitive touch sensor. As shown in Figure 1, the sensor section 10A includes a first electrode 11, a second electrode 12, a third electrode 13, and a fourth electrode 14.

[0020] (First Electrode) As shown in Figure 1, the first electrode 11 illustrated in this embodiment is located on the left side of the paper in the first direction D1 shown in Figure 1, when viewed from above.

[0021] As shown in Figure 2, the first electrode 11 is located on the upper surface of the first substrate 3. Although not shown in the figure, the first electrode 11, like the first excitation element 21 described later, includes a wiring pattern (e.g., a mesh pattern) formed by a plurality of fine metal wires 41 (described later).

[0022] The first electrode 11 extends in a second direction D2 that is perpendicular to the first direction D1. Specifically, the first electrode 11 extends in a roughly strip-like shape along the second direction D2.

[0023] The length L2 of the first electrode 11 along the second direction D2 is λg / 2 or greater. When the length L2 of the first electrode 11 along the second direction D2 is λg / 2 or greater, the resonant frequency does not change, and the current distribution on the first electrode 11 is close to that of a harmonic current distribution. However, the length L2 of the first electrode 11 along the second direction D2 may be less than λg / 2. When the length L2 of the first electrode 11 along the second direction D2 is less than λg / 2, the resonant frequency shifts to the higher frequency side.

[0024] (Second electrode) As shown in Figure 1, the second electrode 12 is located in the first direction D1 relative to the first electrode 11. Specifically, the second electrode 12 is located in the first direction D1 relative to the first electrode 11.

[0025] Furthermore, the second electrode 12 is adjacent to the first electrode 11. Specifically, the second electrode 12 is separated from the first electrode 11 in the first direction D1.

[0026] The second electrode 12 extends in the second direction D2. Specifically, the second electrode 12 extends in a roughly strip-like shape along the second direction D2.

[0027] As shown in Figure 2, the second electrode 12 is located on the upper surface of the first substrate 3. That is, the second electrode 12 is provided in the same layer as the first electrode 11. Although not shown in the figure, the second electrode 12 also includes a wiring pattern formed by a plurality of fine metal wires 41, similar to the first electrode 11.

[0028] (Third electrode) As shown in Figure 1, the third electrode 13 is located in the second direction D2 relative to the first excitation element 21, which will be described later. The third electrode 13 is separated from the first excitation element 21 in the second direction D2.

[0029] The third electrode 13 extends in the first direction D1. Specifically, the third electrode 13 extends in a roughly strip-like shape along the first direction D1.

[0030] As shown in Figure 3, the third electrode 13 is located on the upper surface of the second substrate 4. That is, the third electrode 13 is located on the same layer as the first excitation element 21. Although not shown in the figure, the third electrode 13 also includes a wiring pattern formed by a plurality of fine metal wires 41, similar to the first electrode 11.

[0031] (Fourth electrode) As shown in Figure 1, the fourth electrode 14 is positioned in the opposite direction to the second direction D2 relative to the first excitation element 21, which will be described later. The fourth electrode 14 is separated from the first excitation element 21 in the opposite direction to the second direction D2.

[0032] The fourth electrode 14 extends in the first direction D1. Specifically, the fourth electrode 14 extends in a roughly strip-like shape along the first direction D1.

[0033] As shown in Figure 3, the fourth electrode 14 is located on the upper surface of the second substrate 4. That is, the fourth electrode 14 is located on the same layer as the third electrode 13 and the first excitation element 21. Although not shown in the figure, the fourth electrode 14 also includes a wiring pattern formed by a plurality of fine metal wires 41, similar to the first electrode 11.

[0034] (Excitation section) The excitation section 20 illustrated in this embodiment functions as a monopole antenna. As shown in Figure 1, the excitation section 20 includes a first excitation element 21, a second excitation element 22, a third excitation element 23, a fourth excitation element 24, and an impedance matching element 25.

[0035] (First Excitation Element) As shown in Figure 1, the first excitation element 21 extends in the first direction D1. The length of the first excitation element 21 along the first direction D1 is shorter than 1 / 4 of the wavelength of the electric field corresponding to, for example, the communication frequency in the 2.4 GHz band. Details of the length of the first excitation element 21 along the first direction D1 (characteristic configuration of the first excitation element) will be described later.

[0036] Herein, in this disclosure, an object "extends in a first direction D1" means that the length of the object along the first direction D1 is longer than the length of the object along a direction perpendicular to the first direction D1.

[0037] The first excitation element 21 has a first power supply point 31. The first power supply point 31 is located in the direction opposite to the first direction D1 of the first electrode 11.

[0038] The first excitation element 21 has a first end 21a and a second end 21b.

[0039] The first end 21a is located in the direction opposite to the first direction D1 of the first electrode 11. That is, the first end 21a is located in the direction opposite to the first direction D1 with respect to the first electrode 11.

[0040] The second end 21b is located in the first direction D1 relative to the first end 21a. That is, the second end 21b is located in the first direction D1 relative to the first end 21a.

[0041] The first end 21a, the first power supply point 31, and the second end 21b are located in this order of the first end 21a, the first power supply point 31, and the second end 21b along the first direction D1.

[0042] As shown in FIG. 2, the first excitation element 21 is located on the upper surface of the second substrate 4. That is, the first excitation element 21 is provided on the upper layer of the first electrode 11 and the second electrode 12. Thereby, the radio wave radiated from the first excitation element 21 is not inhibited by the first electrode 11 and the second electrode 12. As a result, the radio wave radiated from the first excitation element 21 can be radiated to the opposite side of the side where the metal such as the sensor unit 10A (specifically, a plurality of metal thin wires constituting the first electrode 11 and the second electrode 12) is located. That is, the radio wave generated from the first excitation element 21 can be radiated upward from the upper surface of the second substrate 4 (see FIG.  2) where the first electrode 11 and the second electrode 12 are located.

[0043] As described above, the first excitation element 21 is located on the upper surface of the second substrate 4. That is, the first excitation element 21 illustrated in this embodiment is provided in the same layer as the third electrode 13 and the fourth electrode 14 (see FIG. 3). Then, as shown in FIG. 1, the first excitation element 21 is located between the third electrode 13 and the fourth electrode 14 in the second direction D2. With such a configuration, the third electrode 13 and the fourth electrode 14 are less likely to be affected by the radio wave generated from the first excitation element 21. As a result, the function of the touch sensor in the sensor unit 10A is ensured. Moreover, since the first excitation element 21 is provided in the same layer as the third electrode 13 and the fourth electrode 14, the entire antenna unit 1A can be made thin.

[0044] Although not shown, the first excitation element 21 may be located in an upper layer than the third electrode 13 and the fourth electrode 14.

[0045] (Relationship between the first excitation element and the first and second electrodes) In the antenna unit 1A according to the first embodiment of this disclosure, when the sensor unit 10A (touch sensor) is touched with a finger or the like (hereinafter simply referred to as "touch operation"), capacitance is formed between the sensor unit 10A (for example, the first electrode 11 and the second electrode 12) and the finger. The third electrode 13 or the fourth electrode 14 then detects the change in capacitance between the sensor unit 10A at a reference time (capacitance of the sensor unit 10A when not touched) and the capacitance of the sensor unit 10A when touched. As a result, the sensor function of the sensor unit 10A makes it possible to detect touch operations (touch operation on the sensor unit 10A and the touch position when the touch operation is performed).

[0046] Based on the sensor function of the sensor unit 10A described above, we will now describe a provisional first configuration (not shown) that differs from the first embodiment of this disclosure, in which the length of the first direction D1 is longer than the length of the first excitation element 21 shown in Figure 1, and the excitation element is configured to overlap with both the first electrode 11 and the second electrode 12 when viewed from above (hereinafter referred to as "excitation element relating to the provisional first configuration").

[0047] As described above, the excitation element of the provisional first configuration overlaps with the first electrode 11 in a top view, thereby forming a capacitance between the excitation element of the provisional first configuration and the first electrode 11. In other words, the excitation element of the provisional first configuration and the first electrode 11 are capacitively coupled. Furthermore, the excitation element of the provisional first configuration overlaps with the second electrode 12 in a top view, thereby forming a capacitance between the excitation element of the provisional first configuration and the second electrode 12. In other words, the excitation element of the provisional first configuration and the second electrode 12 are capacitively coupled.

[0048] From the above, in an antenna unit (not shown) including a vibration element according to a provisional first configuration, the first electrode 11 and the second electrode 12 are pseudo-capacitively coupled. Due to the pseudo-capacitive coupling between the first electrode 11 and the second electrode 12, for example, even when a finger or the like touches only the first electrode 11, the capacitances of both the first electrode 11 and the second electrode 12 change. As a result, in the above-described provisional first configuration, due to the presence of the vibration element according to the provisional first configuration, the sensor function of the sensor unit 10A (touch sensor) may malfunction.

[0049] In contrast, as shown in FIGS. 1 and 2, the first vibration element 21 of the first embodiment overlaps the first electrode 11 in a top view. On the other hand, the first vibration element 21 does not overlap the second electrode 22 in a top view. That is, the first vibration element 21 is separated from the second electrode 22 in the first direction D1 in a top view. Thus, since the first vibration element 21 does not overlap the second electrode 12 in a top view, no capacitance is formed between the first vibration element 21 and the second electrode 12. As a result, unlike the above-described provisional first configuration, the first vibration element 21 and the second electrode 12 of the first embodiment are not capacitively coupled.

[0050] Therefore, for example, even when the first vibration element 21 and the first electrode 11 are capacitively coupled, the first vibration element 21 and the second electrode 12 are not capacitively coupled. Thereby, the pseudo-capacitive coupling between the first electrode 11 and the second electrode 12 can be prevented. Therefore, regardless of the presence of the first vibration element 21, malfunction of the first electrode 11 and the second electrode 12 (the above-described sensor function as a touch sensor in the sensor unit 10A) can be prevented.

[0051] (Characteristic configuration of the first vibration element) In the antenna unit 1A according to the first embodiment of the present disclosure, the length of the first vibration element 21 along the first direction D1 is characteristic. Specifically, as a characteristic configuration of the present disclosure, when the wavelength considering wavelength shortening by surrounding members such as glass is λg at the frequency corresponding to the first vibration element 21, the length L1 of the first vibration element 21 along the first direction D1 is 11λg / 80 or less. The length L1 of the first vibration element 21 along the first direction D1 is the length between the first end 21a and the second end 21b shown in FIG. 1.

[0052] Here, the wavelength λg considering the above wavelength shortening is expressed by the following formula (general formula), using the wavelength λ corresponding to the first excitation element 21 and the relative permittivity εr in the environment surrounding the first excitation element 21.

[0053] [Mathematics 1]

[0054] Figure 5 is a graph with the horizontal axis representing the length L1 (in mm) along the first direction D1 of the first excitation element 21, and the vertical axis representing the resonant frequency (center frequency, in GHz). In Figure 5, the frequency corresponding to the first excitation element 21 is calculated as 2.4 GHz (wavelength λ = 120 mm).

[0055] When the horizontal axis is frequency and the vertical axis is radio wave intensity, the radio waves emitted from the first excitation element 21 form a curve with a half-width of 0.8 GHz centered on the resonant frequency. Therefore, in order to obtain a certain level of radio wave intensity in the 2.4 GHz frequency band, the resonant frequency needs to be between 2.0 GHz and 2.8 GHz (see the region indicated by dot hatching in Figure 2).

[0056] When the antenna unit 1A according to the first embodiment of this disclosure is actually used, wavelength shortening occurs in the radio waves radiated from the first excitation element 21 due to the members (relative permittivity of the members) located around the antenna (first excitation element 21). Examples of members located around the first excitation element 21 include a cover glass (not shown) placed on the upper surface side of the second substrate 4 as illustrated in Figures 2 and 3, or an adhesive layer (not shown) provided between the second substrate 4 and the cover glass. In the first embodiment of this disclosure, the wavelength λg is determined after comprehensively considering the relative permittivity εr of each member, such as the cover glass and the adhesive layer. Specifically, in the first embodiment of this disclosure, the wavelength λg is set to "80 mm" considering a wavelength shortening of "2 / 3".

[0057] As shown by the curve Cv in Figure 5, when the length of the first excitation element 21 is 11 mm or less, the resonant frequency will be between 2.0 GHz and 2.8 GHz, and the frequency corresponding to the first excitation element 21 will correspond to a frequency of 2.4 GHz. In other words, when the length L1 of the first excitation element 21 along the first direction D1 is 11λg / 80 or less, even with a configuration combining the sensor unit 10A and the excitation unit 20 (monopole antenna), the radio waves radiated from the first excitation element 21 can be appropriately matched to a predetermined frequency (for example, the 2.4 GHz frequency band mentioned above).

[0058] (Wiring pattern of the first excitation element) As shown in Figure 4, the first excitation element 21 includes a wiring pattern 40. The wiring pattern 40 is formed by a plurality of fine metal wires 41. Specifically, the wiring pattern 40 is formed in a mesh shape by a plurality of fine metal wires 41. With this configuration, radio waves generated from the first excitation element 21 can pass through the mesh-like openings that make up the wiring pattern 40. Therefore, a decrease in the performance of the first excitation element 21 as an antenna in the excitation unit 20 can be prevented.

[0059] The wiring pattern 40 includes a plurality of cells C1 (a plurality of unit structures). Each cell C1 has a rectangular shape. In this embodiment, the rectangular shape is a rhombus. Although not shown, the rectangular shape may be a square or a rectangle. Furthermore, the shape of the cell C1 is not limited to the rectangular shape described above, and may be, for example, a curved shape or a circle (not shown). Also, although not shown, the wiring pattern 40 may be formed as a random mesh pattern with random shapes including cells such as curved shapes or circles.

[0060] The metal wire 41 illustrated in this embodiment is formed in a straight line. The metal wire 41 extends diagonally with respect to the first direction D1 and the second direction D2 shown in Figure 4. The metal wire 41 may also extend along either the first direction D1 or the second direction D2.

[0061] The metal wire 41 is not limited to being straight. For example, although not shown in the figures, the metal wire 41 may be formed in a curved shape. Also, a plurality of metal wires 41 may include both straight metal wires 41 and curved metal wires 41.

[0062] (Dummy pattern of the excitation unit) As shown in Figure 4, the excitation unit 20 further includes a dummy pattern 50.

[0063] The dummy pattern 50 is located on the upper surface of the second substrate 4, similar to the first excitation element 21. In other words, the dummy pattern 50 is located on the same layer as the first excitation element 21.

[0064] The dummy pattern 50 is spaced apart from the first excitation element 21. For example, the dummy pattern 50 is positioned at a distance from the first excitation element 21 that corresponds to the dimension E shown in Figure 4 (corresponding to the length of the slit 51 described later).

[0065] The dummy pattern 50, like the first excitation element 21, is formed by a plurality of thin metal wires 41. Specifically, the dummy pattern 50 is formed in a mesh-like manner by a plurality of thin metal wires 41.

[0066] The dummy pattern 50 contains multiple cells C2 (multiple unit structures). The cells C2 (unit structures) of the dummy pattern 50 have the same shape as the cells C1 (unit structures) of the wiring pattern 40. Here, "same shape" includes the range of manufacturing errors. Furthermore, even if the dummy pattern 50 or the wiring pattern 40 each have defects (including minute slits not shown), if the overall shape is the same as the defects, the unit structures of the dummy pattern 50 and the unit structures of the wiring pattern 40 are considered to have the same shape. This reduces the difference in appearance between the area where the first excitation element 21 is located and the area where the first excitation element 21 is not located. Therefore, it is possible to make it difficult for the user of the antenna unit 1A to see the first excitation element 21.

[0067] Furthermore, as shown in Figure 4, the dummy pattern 50 has multiple slits 51, which makes it less likely for the dummy pattern 50 to obstruct the electric field lines radiated from the first excitation element 21 on the same plane. Thus, the influence of the dummy pattern 50 on the antenna performance of the first excitation element 21 can be reduced.

[0068] (Second and third excitation elements) As shown in Figure 1, the excitation unit 20 includes a second excitation element 22 and a third excitation element 23.

[0069] The second excitation element 22 is located in the second direction D2 relative to the first excitation element 21. The second excitation element 22 extends in the second direction D2.

[0070] The second excitation element 22 has, for example, a non-powered contact 32 that is at ground potential (GND). Note that the potential of the non-powered contact 32 is not limited to ground potential, but can be lower than the potential of the first power supply point 31.

[0071] The third excitation element 23 is located in the opposite direction to the second direction D2 of the first excitation element 23. The third excitation element 23 extends in the second direction D2.

[0072] The third excitation element 23 has, for example, a non-powered contact 33 that is at ground potential (GND). Note that the potential of the non-powered contact 33 is not limited to ground potential, but can be lower than the potential of the first power supply point 31.

[0073] The excitation unit 20 includes a second excitation element 22, which generates an electric field between the first excitation element 21 and the second excitation element 22. Furthermore, the excitation unit 20 includes a third excitation element 23, which generates an electric field between the first excitation element 21 and the third excitation element 23. This ensures the antenna characteristics of the first excitation element 21.

[0074] The length L3 of the second excitation element 22 along the second direction D2 is equal to the length L1 of the first excitation element 21 along the first direction D1. Therefore, it is possible to make the second excitation element 22 correspond to the same frequency as the first excitation element 21. As a result, the electric field generated between the first excitation element 21 and the second excitation element 22 is stabilized.

[0075] Furthermore, the length L4 of the third excitation element 23 along the second direction D2 is equal to the length L1 of the first excitation element 21 along the first direction D1. Therefore, it is possible to make the third excitation element 23 correspond to the same frequency as the first excitation element 21. This stabilizes the electric field generated between the first excitation element 21 and the third excitation element 23.

[0076] In this way, the antenna characteristics of the first excitation element 21 can be ensured by the second excitation element 22, which has a length L3 along the second direction D2, and the third excitation element 23, which has a length L4 along the second direction D2.

[0077] (Fourth Excitation Element) As shown in Figure 1, the excitation unit 20 further comprises a fourth excitation element 24. The fourth excitation element 24 extends from the second excitation element 22 in the first direction D1.

[0078] The length L5 of the fourth excitation element 24 along the first direction D1 is shorter than the length L1 of the first excitation element 21 along the first direction D1. By providing the fourth excitation element 24, it is possible to make the fourth excitation element 24 correspond to radio waves in a different frequency band than the first excitation element 21. For example, the length of the fourth excitation element 24 along the first direction D1 can be set to 1 / 4 the length of the wavelength of the electric field corresponding to the 5.0 GHz band communication frequency.

[0079] (Impedance Matching Element) As shown in Figure 1, the excitation unit 20 further includes an impedance matching element 25. The impedance matching element 25 connects the first excitation element 21 and the third excitation element 23. This impedance matching element 25 allows for adjustment of the impedance matching in the first excitation element 21.

[0080] [Second Embodiment] Figure 3 is a plan view of the antenna unit 1B according to the second embodiment. The touch sensor (sensor unit 10B) according to the second embodiment is a self-capacitive touch sensor.

[0081] In the following description of the second embodiment, the same reference numerals as those used in the first embodiment will be used for components similar to those in the antenna unit 1A according to the first embodiment, and a detailed explanation of such components will be omitted.

[0082] (Sensor section) As shown in Figure 6, the antenna unit 1B according to the second embodiment includes a sensor section 10B. The sensor section 10B includes a first electrode 71, a second electrode 72, a fifth electrode 75, and a sixth electrode 76.

[0083] (First Electrode) The first electrode 71 illustrated in this embodiment is located on the left side of the paper in the first direction D1 shown in Figure 6, when viewed from above. The first electrode 71 is also located approximately in the center of the substrate 2 in the second direction D2 shown in Figure 6, when viewed from above. The first electrode 71 overlaps with the first excitation element 21 when viewed from above.

[0084] As shown in Figure 7, the first electrode 71 is located on the upper surface of the first substrate 3. Although not shown in the figure, the first electrode 71, like the first excitation element 21, includes a wiring pattern (e.g., a mesh pattern) formed by a plurality of fine metal wires 41 (see Figure 4).

[0085] The first electrode 71 is formed in a substantially rectangular shape when viewed from above. In this embodiment, the first electrode 71 is formed in a square shape when viewed from above. Although not shown in the figures, the first electrode 71 is not limited to a rectangular shape, and may be a polygonal shape other than a rectangular shape or a circular shape, for example.

[0086] (Second electrode) The second electrode 72 illustrated in this embodiment is located in a first direction D1 relative to the first electrode 71 (see Figure 6). The second electrode 72 is separated from the first electrode 71 in the first direction D1. The second electrode 72 does not overlap with the first excitation element 21 when viewed from above.

[0087] As shown in Figure 7, the second electrode 72 is located on the upper surface of the first substrate 3. That is, the second electrode 72 is provided in the same layer as the first electrode 71. Although not shown in the figure, the second electrode 72 also includes a wiring pattern formed by a plurality of fine metal wires 41, similar to the first electrode 71.

[0088] The second electrode 72 is formed in a square shape when viewed from above, similar to the first electrode 71. However, the second electrode 72 is not limited to a square shape; for example, it may have a shape other than a square.

[0089] (Fifth electrode) The fifth electrode 75 illustrated in this embodiment is located in a second direction D2 relative to the first electrode 71. The fifth electrode 75 is separated from the first electrode 71 in the second direction D2.

[0090] As shown in Figure 8, the fifth electrode 75 is located on the upper surface of the first substrate 3. That is, the fifth electrode 75 is located on the same layer as the first electrode 71. Although not shown in the figure, the fifth electrode 75 also includes a wiring pattern formed by multiple metal wires 41, similar to the first electrode 71.

[0091] The fifth electrode 75 is formed in a square shape when viewed from above, similar to the first electrode 71. However, the fifth electrode 75 is not limited to a square shape; for example, it may have a shape other than a square.

[0092] (Sixth electrode) The sixth electrode 76 illustrated in this embodiment is positioned in the opposite direction to the second direction D2 relative to the first electrode 71. The sixth electrode 76 is separated from the first electrode 71 in the opposite direction to the second direction D2.

[0093] As shown in Figure 8, the sixth electrode 76 is located on the upper surface of the first substrate 3. That is, the sixth electrode 76 is located on the same layer as the first electrode 71. Although not shown in the figure, the sixth electrode 76 also includes a wiring pattern formed by multiple metal wires 41, similar to the first electrode 71.

[0094] The sixth electrode 76 is formed in a square shape when viewed from above, similar to the first electrode 71. However, the sixth electrode 76 is not limited to a square shape; for example, it may have a shape other than a square.

[0095] (Characteristic Configuration of the First Excitation Element) Even the antenna unit 1B according to the first embodiment of this disclosure has the same characteristic configuration as the antenna unit 1A according to the first embodiment. That is, even in the antenna unit 1B, if the wavelength λg is taken into account by the wavelength shortening due to surrounding materials such as glass at the frequency to which the first excitation element 21 corresponds, the length L1 of the first excitation element 21 along the first direction D1 is 11λg / 80 or less. With this configuration, as described in the first embodiment, the radio waves radiated from the first excitation element 21 can be appropriately matched at a predetermined frequency (for example, the 2.4 GHz frequency band described above).

[0096] (Relationship between the first excitation element and the fifth and sixth electrodes) Here, we describe a provisional second configuration (not shown) that differs from the second embodiment of this disclosure, in which an excitation element is configured to overlap both the first electrode 71 and the fifth electrode 75 in a top view (hereinafter referred to as the "excitation element relating to the provisional second configuration").

[0097] In the provisional second configuration, the excitation element related to the provisional second configuration overlaps with the first electrode 71 in a top view, thereby forming a capacitance between the excitation element related to the provisional second configuration and the first electrode 71. In other words, the excitation element related to the provisional second configuration and the first electrode 71 are capacitively coupled.

[0098] Furthermore, in the above-described provisional second configuration, the excitation element related to the provisional second configuration overlaps with the fifth electrode 75 in a top view, thereby forming capacitance between the excitation element related to the provisional second configuration and the fifth electrode 75. In other words, the excitation element related to the provisional second configuration and the fifth electrode 75 are capacitively coupled.

[0099] Based on the above, in the provisional second configuration, the first electrode 71 and the fifth electrode 75 are pseudo-capacitively coupled. Due to this pseudo-capacitive coupling between the first electrode 71 and the fifth electrode 75, even when the first electrode 71 is touched, both the first electrode 71 and the fifth electrode 75 undergo a change in capacitance. As a result, the sensor function of the sensor unit 10B (touch sensor) may malfunction.

[0100] In contrast, the first excitation element 21 according to the second embodiment of this disclosure overlaps with the first electrode 71 when viewed from above. Furthermore, the first excitation element 21 does not overlap with the fifth electrode 75 when viewed from above. Therefore, even if the first excitation element 21 and the first electrode 71 are capacitively coupled, the first excitation element 21 and the fifth electrode 75 are not capacitively coupled. This prevents pseudo-capacitive coupling between the first electrode 71 and the fifth electrode 75.

[0101] Furthermore, the first excitation element 21 does not overlap with the sixth electrode 76 when viewed from above. Therefore, even if the first excitation element 21 and the first electrode 71 are capacitively coupled, the first excitation element 21 and the sixth electrode 76 will not be capacitively coupled. This prevents pseudo-capacitive coupling between the first electrode 71 and the sixth electrode 76. Thus, regardless of the presence of the first excitation element 21, malfunctions of the sensor function in the sensor unit 10B (touch sensor) can be prevented.

[0102] Thus, in the antenna unit 1B according to the second embodiment, the first excitation element 21 does not overlap with either the fifth electrode 75 or the sixth electrode 76 when viewed from above. Therefore, regardless of the presence of the first excitation element 21, malfunctions of the functions of the fifth electrode 75 and the sixth electrode 76 (function as touch sensors) can be prevented.

[0103] (Metal plate) As shown in Figure 6, the antenna unit 1B according to the second embodiment includes a metal plate 60. The metal plate 60 is formed in a rectangular shape when viewed from above, for example.

[0104] As shown in Figures 7 and 8, the metal plate 60 is laminated on the underside of the first substrate 3 via the adhesive layer 5. That is, the metal plate 60 is located below the first electrode 71.

[0105] The length L6 of the metal plate 60 along the second direction D2 is λg / 2 or less. When the length L6 of the metal plate 60 along the second direction D2 is shorter than λg / 2, the resonant frequency shifts to the higher frequency side. On the other hand, when the length L6 of the metal plate 60 along the second direction D2 is λg / 2 or more, the resonant frequency does not change.

[0106] [Summary] As a first disclosure, the antenna unit 1A includes a first electrode 11, a second electrode 12 located in a first direction D1 of the first electrode 11 and adjacent to the first electrode 11, and a first excitation element 21 provided on the upper layer between the first electrode 11 and the second electrode 12 and extending in the first direction D1. The first excitation element 21 has a first end 21a located in the direction opposite to the first direction D1 of the first electrode 11, and a second end 21b located in the first direction D1 of the first end 21a. When the wavelength considering wavelength shortening is λg at the frequency corresponding to the first excitation element 21, the length between the first end 21a and the second end 21b of the first excitation element 21 is 11λg / 80 or less.

[0107] In the first disclosure, as shown by the curve Cv in Figure 5, when the length of the first excitation element 21 is 11 mm or less, the resonant frequency will be between 2.0 GHz and 2.8 GHz, and the frequency to which the first excitation element 21 corresponds will be 2.4 GHz. That is, when the length L1 of the first excitation element 21 along the first direction D1 is 11λg / 80 or less, the radio waves radiated from the first excitation element 21 can be appropriately matched to a predetermined frequency (for example, a 2.4 GHz frequency band).

[0108] As a second disclosure, the first excitation element 21 overlaps with the first electrode 11 when viewed from above. The first excitation element 21 does not overlap with the second electrode 12 when viewed from above.

[0109] In the second disclosure, since the first excitation element 21 does not overlap with the second electrode 12 in a top view, the first excitation element 21 and the second electrode 12 do not become capacitively coupled. This makes it possible to prevent pseudo-capacitive coupling between the first electrode 11 and the second electrode 12. Therefore, regardless of the presence of the first excitation element 21, malfunctions of the first electrode 11 and the second electrode 12 (malfunctions of the sensor unit 10A) can be prevented.

[0110] As a third disclosure, the first excitation element 21 includes a wiring pattern 40 formed by a plurality of fine metal wires 41.

[0111] In the third disclosure, as described in the first embodiment above, it is possible to prevent a decrease in the performance of the antenna in the first excitation element 21.

[0112] As a fourth disclosure, the device further comprises a dummy pattern 50 located in the same layer as the first excitation element 21, separated from the first excitation element 21, and formed by a plurality of fine metal wires 41. The unit structure of the dummy pattern 50 has the same shape as the unit structure of the wiring pattern 40.

[0113] In the fourth disclosure, as described in the first embodiment above, the difference in appearance between the region where the first excitation element 21 is located and the region where the first excitation element 21 is not located can be reduced. Therefore, it is possible to make it difficult for the user of the antenna unit 1A to see the first excitation element 21.

[0114] As a fifth disclosure, the dummy pattern 50 has a slit 51.

[0115] In the fifth disclosure, the dummy pattern 50 is less likely to obstruct the electric field lines radiated from the first excitation element 21 on the same plane. Therefore, the influence of the dummy pattern 50 on the antenna performance of the first excitation element 21 can be reduced.

[0116] As a sixth disclosure, the antenna unit 1A further comprises a third electrode 13 located in a second direction D2 of the first excitation element 21, and a fourth electrode 14 located in the opposite direction to the second direction D2 of the first excitation element 21. The first electrode 11 extends in a second direction D2 perpendicular to the first direction D1. The second electrode 12 extends in the second direction D2. The third electrode 13 extends in the first direction D1. The fourth electrode 14 extends in the first direction D1. The first excitation element 21 is located between the third electrode 13 and the fourth electrode 14.

[0117] In the sixth disclosure, since the first excitation element 21 is located between the third electrode 13 and the fourth electrode 14, the third electrode 13 and the fourth electrode 14 are less susceptible to the influence of radio waves generated from the first excitation element 21. As a result, the function of the third electrode 13 and the fourth electrode 14 (the function of the sensor unit 10A) is ensured. Furthermore, since the first excitation element 21 is provided in the same layer as the third electrode 13 and the fourth electrode 14 (see Figure 3), the overall thickness of the antenna unit 1A can be reduced.

[0118] As a seventh disclosure, the antenna unit 1B further comprises a fifth electrode 75 located in a second direction D2 perpendicular to the first direction D1 of the first electrode 71, a sixth electrode 76 located in the opposite direction to the second direction D2 of the first electrode 71, and a metal plate 60 located in a lower layer of the first electrode 71. The fifth electrode 75 is located in the same layer as the first electrode 71. The sixth electrode 76 is located in the same layer as the first electrode 71. The first excitation element 21 does not overlap with the fifth electrode 75 when viewed from above. The first excitation element 21 does not overlap with the sixth electrode 76 when viewed from above.

[0119] In the seventh disclosure, since the first excitation element 21 does not overlap with the fifth electrode 75 when viewed from above, the first excitation element 21 and the fifth electrode 75 do not capacitively couple. This prevents pseudo-capacitive coupling between the first electrode 71 and the fifth electrode 75. Also, since the first excitation element 21 does not overlap with the sixth electrode 76 when viewed from above, the first excitation element 21 and the sixth electrode 76 do not capacitively couple. This prevents pseudo-capacitive coupling between the first electrode 71 and the sixth electrode 76. Therefore, in the seventh disclosure, malfunctions of the fifth electrode 75 and the sixth electrode 76 (sensor function in sensor unit 10B) can be prevented regardless of the presence of the first excitation element 21.

[0120] As the eighth disclosure, the antenna unit 1A (antenna unit 1B) further comprises a second excitation element 22 located in a second direction D2 perpendicular to the first direction D1 of the first excitation element 21 and extending in the second direction D2, and a third excitation element 23 located in the direction opposite to the second direction D2 of the first excitation element 21 and extending in the second direction D2.

[0121] In the eighth disclosure, an electric field is generated between the first excitation element 21 and the second excitation element 22. An electric field is also generated between the first excitation element 21 and the third excitation element 23. This ensures the antenna characteristics of the first excitation element 21.

[0122] As the ninth disclosure, the length of the second excitation element 22 along the second direction D2 is equal to the length of the first excitation element 21 along the first direction D2. The length of the third excitation element 23 along the second direction D2 is equal to the length of the first excitation element 21 along the first direction D1.

[0123] In the ninth disclosure, since the length of the second excitation element 22 along the second direction D2 is equal to the length of the first excitation element 21 along the first direction D2, it becomes possible to make the second excitation element 22 correspond to the same frequency as the frequency corresponding to the first excitation element 21. As a result, the electric field generated between the first excitation element 21 and the second excitation element 22 is stabilized.

[0124] Furthermore, since the length of the third excitation element 23 along the second direction D2 is equal to the length of the first excitation element 21 along the first direction D1, it is possible to make the third excitation element 23 correspond to the same frequency as the first excitation element 21. This stabilizes the electric field generated between the first excitation element 21 and the third excitation element 23.

[0125] Therefore, the second excitation element 22 and the third excitation element 23 in the ninth disclosure can ensure the antenna characteristics of the first excitation element 21.

[0126] As a tenth disclosure, the antenna unit 1A (antenna unit 1B) further comprises a fourth excitation element 24 extending from the second excitation element 22 in a first direction D1. The length of the fourth excitation element 24 along the first direction D1 is shorter than the length of the first excitation element 21 along the first direction D1.

[0127] In the tenth disclosure, the fourth excitation element 24 can be made to correspond to radio waves in a different frequency band than the first excitation element 21.

[0128] As the eleventh disclosure, the antenna unit 1A (antenna unit 1B) further comprises an impedance matching element 25 that connects the first excitation element 21 and the third excitation element 23.

[0129] The eleventh disclosure allows for adjustment of impedance matching in the first excitation element 21.

[0130] As a twelfth disclosure, the antenna unit 1A includes a first electrode 11, a second electrode 12 located in a first direction D1 of the first electrode 11 and adjacent to the first electrode 11, and a first excitation element 21 provided on the upper layer between the first electrode 11 and the second electrode 12 and extending in the first direction D1. The first excitation element 21 overlaps with the first electrode 11 in a top view. The first excitation element 21 does not overlap with the second electrode 11 in a top view.

[0131] In the twelfth disclosure, since the first excitation element 21 does not overlap with the second electrode 12 in a top view, the first excitation element 21 and the second electrode 12 do not become capacitively coupled. This makes it possible to prevent pseudo-capacitive coupling between the first electrode 11 and the second electrode 12. Therefore, regardless of the presence of the first excitation element 21, malfunctions of the first electrode 11 and the second electrode 12 (malfunctions of the sensor unit 10A) can be prevented. Furthermore, the antenna unit 1B can also achieve the same effects as those described above in the twelfth disclosure.

[0132] This disclosure is applicable to industrial use as an antenna unit.

[0133] 1A, 1B: Antenna unit 2: Substrate 3: First substrate 4: Second substrate 5: Adhesive layer 10A, 10B: Sensor section 11, 71: First electrode 11, 72, Second electrode 13: Third electrode 14: Fourth electrode 20: Excitation section 21: First excitation element 21a: First end 21b: Second end 22: Second excitation element 23: Third excitation element 24: Fourth excitation element 25: Impedance matching element 31: First feed point 40: Wiring pattern 41: Metal wire 50: Dummy pattern 51: Slit 60: Metal plate 75: Fifth electrode 76: Sixth electrode C1, C2: Cell (unit structure) D1: First direction D2: Second direction

Claims

1. An antenna unit comprising: a first electrode; a second electrode located in a first direction from the first electrode and adjacent to the first electrode; and a first excitation element provided on the upper layer between the first electrode and the second electrode and extending in the first direction, wherein the first excitation element has a first end located in the direction opposite to the first direction from the first electrode, and a second end located in the first direction from the first end, and when the wavelength considering wavelength shortening is λg at the frequency corresponding to the first excitation element, the length between the first end and the second end of the first excitation element is 11λg / 80 or less.

2. The antenna unit according to claim 1 or 2, wherein the first excitation element overlaps with the first electrode when viewed from above, and the first excitation element does not overlap with the second electrode when viewed from above.

3. The antenna unit according to claim 1 or 2, wherein the first excitation element includes a wiring pattern formed by a plurality of fine metal wires.

4. The antenna unit according to claim 3, further comprising a dummy pattern located in the same layer as the first excitation element, separated from the first excitation element, and formed by a plurality of fine metal wires, wherein the unit structure of the dummy pattern has the same shape as the unit structure of the wiring pattern.

5. The antenna unit according to claim 4, wherein the dummy pattern has a slit.

6. The antenna unit according to any one of claims 1 to 5, further comprising: a third electrode located in the second direction of the first excitation element; and a fourth electrode located in the opposite direction to the second direction of the first excitation element, wherein the first electrode extends in a second direction perpendicular to the first direction; the second electrode extends in the second direction; the third electrode extends in the first direction; the fourth electrode extends in the first direction; and the first excitation element is located between the third electrode and the fourth electrode.

7. The antenna unit according to any one of claims 1 to 6, further comprising: a fifth electrode located in a second direction perpendicular to the first direction of the first electrode; a sixth electrode located in the opposite direction to the second direction of the first electrode; and a metal plate located in a lower layer of the first electrode, wherein the fifth electrode is located in the same layer as the first electrode, the sixth electrode is located in the same layer as the first electrode, the first excitation element does not overlap with the fifth electrode in a top view, and the first excitation element does not overlap with the sixth electrode in a top view.

8. The antenna unit according to any one of claims 1 to 7, further comprising: a second excitation element located in a second direction perpendicular to the first direction of the first excitation element and extending in the second direction; and a third excitation element located in the direction opposite to the second direction of the first excitation element and extending in the second direction.

9. The antenna unit according to claim 8, wherein the length of the second excitation element along the second direction is equal to the length of the first excitation element along the first direction, and the length of the third excitation element along the second direction is equal to the length of the first excitation element along the first direction.

10. The antenna unit according to any one of claims 8 or 9, further comprising a fourth excitation element extending from the second excitation element in the first direction, wherein the length of the fourth excitation element in the first direction is shorter than the length of the first excitation element in the first direction.

11. The antenna unit according to any one of claims 8 to 10, further comprising an impedance matching element connecting the first excitation element and the third excitation element.

12. An antenna unit comprising: a first electrode; a second electrode located in a first direction from the first electrode and adjacent to the first electrode; and a first excitation element provided on the upper layer between the first electrode and the second electrode and extending in the first direction, wherein the first excitation element overlaps with the first electrode in a top view, and the first excitation element does not overlap with the second electrode in a top view.

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