JP7549197B2 - High-frequency signal transmission device and radio using the same - Google Patents

Description

The present invention relates to a radio device, and in particular to a configuration having substrates facing each other in close proximity, for transmitting high-frequency signals between them.

Even handheld radios are becoming more and more multifunctional, not only for voice calls using the conventional VHF and UHF bands, but also for data communication and wider communication areas using mobile phone lines. In addition, component costs have fallen, and even devices that can receive GNSS (Global Navigation Satellite System) signals such as GPS (Global Positioning System) are now available.

Such radio equipment must handle the mobile phone line and GPS signals, which are higher than conventional radio operating frequencies, and must be equipped with multiple radio circuits and digital circuits, requiring multiple boards. In this case, there is no problem if the high-frequency signals can be processed within the same board, but if they need to be transmitted to other boards due to component mounting positions, etc., they will be routed using coaxial cables, even for short distances, in order to reduce transmission loss, since they are high-frequency signals. For example, if the mobile phone line has two antennas with different polarization planes and also receives GPS signals, three coaxial cables may be required.

However, using coaxial cables is not suitable for mechanical assembly and requires manual soldering work, and when storing the cable during assembly, it can get caught between the housings or even cut off, resulting in poor workability during manufacturing and repair. On the other hand, when transmitting high-frequency signals between two boards that are close to each other and face each other, a BtoB connector, which can also transmit high-frequency signals, can be used.

Patent Document 1 describes a connection device for high-frequency circuit boards, such as a BtoB connector, in which multiple mutually parallel conductive patterns are formed on the patterns of two opposing boards, and a columnar member with a cross section resembling an oval cut in half is sandwiched between them, and the conductive patterns are connected by multiple mutually parallel connection electrodes formed on the arc-shaped outer periphery of the columnar member, thereby connecting the boards with a simple structure without degrading the high-frequency characteristics.

JP 2002-176239 A

In the above-mentioned conventional technology, high-frequency signals are transmitted between two facing boards without using a coaxial cable, making it easy to assemble and highly reliable. However, because the conductive pattern is contacted with a connection electrode formed on the outer periphery of the columnar member, a certain height, i.e., spacing between the boards, is required, just like with BtoB connectors, which limits how small (thin) it can be made, and there is a possibility of poor contact due to a slight inclination between the two boards, i.e., the inability to ensure parallelism.

The object of the present invention is to provide a high-frequency signal transmission device and a radio using the same that can reduce component costs and size when transmitting high-frequency signals between two boards that are close to each other and face each other, and can also be easily disassembled for assembly or repair.

The high-frequency signal transmission device of the present invention is an apparatus for transmitting high-frequency signals between substrates that are closely adjacent to each other and face each other, and includes a non-grounded electrode and a grounded electrode formed on both substrates facing each other, capacitors respectively provided between the non-grounded electrode and the grounded electrode, a spring tangent attached to one of the non-grounded electrodes and in contact with the other, and a connecting member that connects the grounded electrodes with a lower impedance than the spring tangent , and is characterized in that a low-pass filter is formed by the capacitor, the spring tangent, and the connecting member, and the filter uses the spring tangent as an inductor .

According to the above configuration, in a device for transmitting high-frequency signals between boards that face each other in close proximity, a spring tangent is used on the non-grounded side, and a connecting member with a lower impedance, for example by making the grounded side larger, is used. In detail, a non-grounded electrode and a grounded electrode are formed facing each other on both boards, and a capacitor (capacitance) is formed between them. Then, when a spring tangent is attached to the non-grounded electrode of one board and the two boards are placed facing each other, the spring tangent comes into contact with the non-grounded electrode of the other board, resulting in a certain inductance component. On the other hand, the grounded electrodes between the two boards are connected with low impedance by a connecting member such as a large-area contact pad, and the GND potential between the two boards is made common.

The capacitance and inductance thus form an equivalent low-pass filter, electrically connecting the two boards. Then, by adjusting the cutoff frequency, which increases as the capacitance and inductance decrease, to be higher than the high-frequency signal to be transmitted, for example by shortening or thickening the tangents and reducing the capacitance, the two boards can be connected without affecting the high-frequency signal, that is, without causing losses due to impedance mismatch.

As a result, when transmitting high-frequency signals between two boards that are close to each other and face each other, they can be connected without using coaxial cables or BtoB connectors. This allows for a significant reduction in component costs and further miniaturization, while also making it easy to disassemble for assembly or repair.

In addition, in the high-frequency signal transmission device of the present invention, the connection member is characterized in that it is made of a conductive sponge interposed between the ground electrode of one substrate and the ground electrode of the other substrate, and has a width longer than the connection distance between the substrates .

According to the above configuration, in order to connect the ground electrodes of the boards facing each other in close proximity with low impedance, it is desirable to be able to absorb the inclination between the boards and to have surface contact. Therefore, using a conductive sponge as the connection member is suitable as it can meet such requirements.

Furthermore, in the high-frequency signal transmission device of the present invention, the ground electrode that contacts the conductive sponge on the other substrate is characterized by being made of a shielding case that covers the components mounted on the other substrate.

According to the above configuration, when connecting the ground electrodes of boards that face each other in close proximity with low impedance, a conductive sponge is used on one side to absorb the tilt and achieve surface contact, while if a shield case is provided on the other side, it is used to bring the conductive sponge into contact.

Therefore, by raising the height using a shielding case with high conductivity, the conductive sponge can be made thinner, and the conductive surface of the conductive sponge can be connected with a width that is much longer than the connection distance between the boards, so the GND potential between the two boards can be more closely matched. Also, even if a large space cannot be secured for the ground electrode due to the presence of components, the ground electrode can be made wider by using a shielding case that spans it.

In addition, in the high-frequency signal transmission device of the present invention, the non-grounded electrode forms the capacitor with a floating capacitance between it and the grounded electrode, and the area of the non-grounded electrode is formed so that the floating capacitance is such that the frequency of the high-frequency signal to be transmitted is below the cutoff frequency of a low-pass filter formed by the capacitor and the inductance of the spring tangent.

According to the above configuration, in order to form the low-pass filter, a capacitor is required in addition to the inductance of the spring tangent, but if the inductance of the spring tangent is small, that is, if the transmission distance is short, the capacitance can also be made small. Therefore, if the spring tangent is short to a certain extent and the area of the non-grounded electrode is made large to a certain extent, the capacitor of the low-pass filter can be realized by the stray capacitance of the non-grounded electrode without the need for a separate capacitor. This allows the number of parts to be reduced.

Furthermore, the radio of the present invention is characterized by being equipped with the above-mentioned high-frequency signal transmission device.

The above configuration allows for a significant reduction in component costs, further miniaturization, and the realization of a radio that can be easily assembled and disassembled for repair.

As described above, the high-frequency signal transmission device of the present invention and the radio using the same transmit high-frequency signals between boards that face each other in close proximity. In this manner, a non-grounded electrode and a grounded electrode are formed on both boards facing each other, and a capacitor (capacitance) is formed between them. A spring tangent is attached to the non-grounded electrode of one board and contacts the non-grounded electrode of the other board. Meanwhile, the grounded electrodes are connected to a low impedance by a connecting member such as a large-area contact pad, and the GND potential between the two boards is made common. Then, a low-pass filter is formed equivalent to the capacitance component by utilizing the inductance component of the spring tangent, which is the cause of the transmission loss of the high-frequency signal, and the inductance component and capacitance component are adjusted so that the frequency of the high-frequency signal is equal to or lower than the cutoff frequency of the low-pass filter.

As a result, two boards can be connected without using coaxial cables or BtoB connectors, and with reduced transmission loss. This allows for a significant reduction in component costs and further miniaturization without degrading high-frequency characteristics, and also makes it easy to disassemble for assembly or repair.

1 is a perspective view of a radio device according to an embodiment of the present invention; FIG. FIG. 2 is a front view showing the inside of the radio device, with the radio device divided into two parts, front and rear. FIG. 4 is a diagram showing the surface of the substrate opposite to that shown in FIG. 3 . 1 is a cross-sectional view showing a schematic diagram of a high-frequency signal transmission device according to an embodiment of the present invention; 5A and 5B are diagrams for explaining stray capacitance formed between a contact and a GND pattern in the transmission device. 6 is an equivalent circuit diagram of the high-frequency signal transmission device of FIG. 5. FIG. 11 is a cross-sectional view illustrating a schematic diagram of a high-frequency signal transmission device according to another embodiment of the present invention.

Figure 1 is a perspective view of a radio 1 according to an embodiment of the present invention, and Figure 2 is a plan view. Radio 1 is a device capable of digital communication using VHF and UHF bands and LTE lines for mobile phones, but the operating frequency band of the radio and whether it is digital or analog are not important to the present invention. As shown in the figure, it is preferably a handheld (small) type radio that receives another high-frequency signal higher than the operating frequency band, in this example a GPS signal or a signal from a mobile phone line. GPS signals are received at a predetermined cycle, for example every second, and when starting to transmit voice or data in the operating frequency band, the most recent location data is included in the signal and transmitted.

The upper part of the housing 10 of the radio 1 is provided with an antenna 11 for the operating frequency, a volume knob 12, and a channel switching knob 13 for selecting a radio channel. As shown in FIG. 2, the antenna 11 is removable at the connector 111, and can be replaced with a shorter antenna or removed and stored. On the front of the housing 10, a speaker 14 is embedded in the upper part, a display unit 16 is provided in the center, and various key switches 17 are provided in the lower part. A microphone 15 is provided adjacent to the speaker 14. Two press-to-talk switches 18 and 19 are provided on the left side of the housing 10. On the back of the housing 10, a clip 20 is provided that is inserted into the user's belt or the like and clamps the belt between the housing 10. A cover 101 on the right side of the housing 10 covers a connector for attaching a separate speaker and microphone in a watertight manner.

Figure 3 is a front view of the radio 1, divided into two halves, front and rear, showing the inside. The antenna 11 can be removed from the connector 111, the volume knob 12 from the rotating shaft 122 of the volume 121, and the channel switching knob 13 from the rotating shaft 132 of the rotary encoder 131; Figure 3 shows them in this state. The housing 10 is roughly divided into a front housing 102 that covers the front and top, and a rear housing 103 at the rear, and the joints between them are watertightly sealed with a sealant (not shown). The housings 102 and 103 are provided with circuit boards 3 and 4, respectively.

Figure 4 shows the surface of boards 3 and 4 opposite to that shown in Figure 3, and Figure 5 shows an enlarged cross section of a portion of board 4. Board 3 on the front housing 102 side is a board made up of parts similar to those of a mobile phone, including a keypad 31 for the key switches 17, an LCD module 32, LTE (mobile phone line) antennas 33 and 34, a GPS antenna 35, and a Bluetooth (registered trademark) unit 36.

On the other hand, the board 4 on the rear housing 103 side is a board on which are mounted a transceiver section 41 that transmits and receives in the VHF and UHF bands, a logic circuit section 42 such as a modulation/demodulation IC and a controller, a SIM card slot 43 for a mobile phone, an LTE module 44, an eccentric motor 47 for vibration, and the like. When the housings 102 and 103 are fitted together, these boards 3 and 4 are electrically connected by contacting the contact 39 and pin 49 for relatively low frequency signals, and by contacting the pins 481 to 485 (hereinafter collectively referred to as 48) and the contacts 381 to 385 (hereinafter collectively referred to as 38) for relatively high frequency signals. The connector 111, the volume 121, and the rotary encoder 131 are provided on the top of the board 4.

In the radio 1 configured as described above, the radio 1 of this embodiment has a GPS antenna 35 and LTE antennas 33, 34 as dedicated high-frequency antennas for receiving other high-frequency signals higher than the operating frequency of the antenna 11. The LTE antennas 33, 34 are arranged on the substrate 3 perpendicular to each other in accordance with the polarization plane. It is noteworthy that the high-frequency signals of the GPS antenna 35 and the LTE antennas 33, 34 mounted on the substrate 3 are transmitted to the substrate 4 by three coaxial cables in the past, but in the radio 1 of this embodiment, they are transmitted using the contacts 38 and pins 48 and the conductive sponge 37 described below.

In the example of FIG. 4, the GPS antenna 35 and LTE antenna 34, which are relatively close to each other, are connected by a common GND pin 483 and GND contact 383 on the ground side, and individual pins 481, 482 and contacts 381, 382 on the non-ground side. The LTE antenna 34, which is a little further away, is connected by a GND pin 485 and GND contact 385 on the ground side, and a pin 484 and contact 384 on the non-ground side.

Figure 5 is a diagram for explaining a high-frequency signal transmission device according to one embodiment of the present invention, and is a cross-sectional view showing the pin 48 and the contact 38. On the opposing surfaces of the boards 3 and 4, GND patterns 30 and 40 that serve as ground electrodes are appropriately routed. It is noteworthy that the radio 1 of this embodiment uses a high-frequency signal transmission device as shown in Figure 5 instead of the coaxial cable to transmit the GPS high-frequency signal and the LTE line high-frequency signal between the boards 3 and 4 that face each other in close proximity.

The pin 48 is a spring tangent formed in a roughly Z-shape in side view, and contacts 46 (461-465 not shown) are formed corresponding to the board 4 and soldered with solder 44. The pin 48 is provided with a chuck that corresponds to a mounting machine or the like as appropriate. The non-grounded contacts 381, 382, 384; 461, 462, 464 become non-grounded electrodes. As shown in FIG. 6 and as described later, the contacts 381, 382, 384; 461, 462, 464 have capacitors 53, 54 due to stray capacitance between them and the GND patterns 30, 40, but as described later, if the capacitance is insufficient, actual capacitors may be connected.

In contrast, between the GND patterns 30 and 40, which serve as the ground electrodes, a conductive sponge 37 is provided on the board 3 side as a connection member, and a shield case 45 is provided on the board 4. The shield case 45 may be provided on the board 3 side, and the conductive sponge 37 may be provided on the board 4 side. The shield case 45 is mounted on the board 4 and covers the components 61 that constitute the LTE (mobile phone line) module 44. The shield case 45 and the conductive sponge 37 have a large area and provide a lower impedance to the high-frequency signal than the contacts 381, 382, 384; 461, 462, 464 and pin 48, and commonize the GND potential between the two boards 3 and 4.

Figure 7 is an equivalent circuit diagram of the transmission device of Figure 5. According to the transmission device configured as described above, when transmitting a high-frequency signal between the boards 3 and 4 facing each other in close proximity, the pin 48, which is a spring tangent, is used on the non-grounded side, and the conductive sponge 37, which is a low-impedance connection member, is used on the grounded side. Therefore, the capacitors (capacitances) 53 and 54 formed between them and the inductance component of the pin 48 equivalently form a low-pass filter and electrically connect the two boards 3 and 4. Then, by shortening or thickening the pin 48 and reducing the capacitance (53, 54), for example, so that the cut-off frequency, which increases as the capacitance (53, 54) and inductance (48) become smaller, becomes higher than the high-frequency signal to be transmitted, the two boards 3 and 4 can be connected without affecting the high-frequency signal, that is, without causing loss due to impedance mismatch.

By configuring it in this way, when transmitting high-frequency signals between the two boards 3 and 4, which are close to each other and face each other, it is possible to connect them without using coaxial cables or BtoB connectors, and with reduced transmission loss. This allows for a significant reduction in component costs, further miniaturization, and easy disassembly for assembly and repair.

In addition, in the transmission device of this embodiment, the connecting member is a conductive sponge 37 that is attached to the ground electrode (30) of one of the boards (3 in the example of FIG. 5), so that the inclination between the boards 3 and 4 can be absorbed and it can be brought into contact with the ground electrode (45-40) of the other board 4. The conductive sponge 37 does not have to be attached, and it is sufficient that part or all of the periphery is held in place by a frame or the like to prevent it from shifting.

Furthermore, in the transmission device of this embodiment, a shield case 45 that covers the components 61 mounted on the other board 4 is used as the ground side electrode that contacts the conductive sponge 37 on the other board 4. Therefore, the ground side electrode is raised by the shield case 45, which has high conductivity, so the conductive sponge 37 can be made thinner, and the conductive surface of the conductive sponge 37 is connected with a width that is sufficiently longer than the connection distance between the boards 3 and 4, so the GND potential between the two boards 3 and 4 can be more closely matched. Also, even if a large space cannot be secured for the ground side electrode 40 due to the presence of components, the ground side electrode 40 can be made wider by using a shield case 45 that spans it.

In addition, when constructing the above low-pass filter, it is necessary to provide capacitors 53 and 54 between the contacts 381, 382, 384; 461, 462, 464, which are non-grounded electrodes, and the GND patterns 30 and 40, which are grounded electrodes. In the transmission device of this embodiment, however, the floating capacitance between them is utilized. The area of the contacts 381, 382, 384; 461, 462, 464, which are non-grounded electrodes, is formed so that the floating capacitance is such that the frequency of the high-frequency signal to be transmitted falls below the cutoff frequency of the low-pass filter formed by the capacitors 53 and 54 and the inductance of the pin 48, which is a spring tangent.

This is because when transmitting a high-frequency signal of a certain frequency, if the inductance of the spring tangent (48) is small, i.e., if the transmission distance is short, the capacitance (53, 54) can also be made small. If the spring tangent (48) is short to a certain extent, and the area of the non-grounded electrodes (381, 382, 384; 461, 462, 464) is made large to a certain extent, the capacitor function of the low-pass filter can be realized by the stray capacitance of the non-grounded electrodes (381, 382, 384; 461, 462, 464), as described above, without the need for a separate capacitor. This allows the number of parts to be reduced.

By incorporating the high-frequency signal transmission device of this embodiment, it is possible to significantly reduce component costs and achieve further miniaturization, as well as to realize a radio device that can be easily assembled and disassembled for repair.

Of the five pins 48, two pins 483 and 485 are for the ground side, i.e., GND. For high-frequency signal transmission, the conductive sponge 37 and shield case 45 mentioned above provide a low impedance connection, but the GND can be reinforced by using these pins 483 and 485 in combination.

In the above embodiment, the shield case 45 covers the component 61 mounted directly on the board 4, but as shown in FIG. 8, in a module structure in which the component 61 is mounted on another board 62, and the other board 62 is further mounted on the board 4, the shield case 45 may be attached to the other board 62.

1 Radio 10 Housing 102 Front housing 103 Rear housing 11 Antenna 111 Connector 12 Volume knob 121 Volume 122 Rotating shaft 13 Channel switching knob 131 Rotary encoder 132 Rotating shaft 14 Speaker 15 Microphone 16 Display unit 17 Key switch 18, 19 Press-to-talk switch 20 Clip 3, 4 Board 30, 40 GND pattern 31 Keypad 32 LCD module 33, 34 LTE antenna 35 GPS antenna 36 Bluetooth (registered trademark) unit 37 Conductive sponge 38; 381 to 385; 39 Contact 41 Transceiver part 42 Logic circuit part 43 SIM card slot 44 LTE (mobile phone line) module 45 Shield case 46; 461 to 465 Contact 47 Eccentric motor for vibration 48; 481 to 485; 49 Pins 53, 54 Capacitor 61 Component 62 Other board

Claims (5)

1. An apparatus for transmitting high frequency signals between substrates facing each other in close proximity, comprising:
a non-grounded electrode and a grounded electrode formed on both substrates so as to face each other;
a capacitor provided between the non-grounded electrode and the grounded electrode;
a spring tangent attached to one of the non-grounded electrodes and in contact with the other of the non-grounded electrodes;
a connection member that connects the ground electrodes to each other at a lower impedance than the spring tangent,
a low-pass filter is formed by the capacitor, the spring tangent, and the connecting member;
The low-pass filter has the spring tangent as an inductor.
A high frequency signal transmission device. 2. The transmission device according to claim 1, wherein the connection member is made of a conductive sponge interposed between the ground electrode of one board and the ground electrode of the other board, the sponge having a width greater than the connection distance between the boards . the connecting member is made of a conductive sponge interposed between a ground electrode of one substrate and a ground electrode of the other substrate,
2. The high frequency signal transmission device according to claim 1, wherein the ground electrode in the other substrate that comes into contact with the conductive sponge is made of a shield case that covers components mounted on the other substrate. The high-frequency signal transmission device according to any one of claims 1 to 3, characterized in that the non-grounded electrode forms the capacitor with a floating capacitance between it and the grounded electrode, and the area of the non-grounded electrode is formed so that the floating capacitance is such that the frequency of the high-frequency signal to be transmitted is below the cutoff frequency of the low-pass filter formed by the capacitor and the inductance of the spring tangent. A radio device comprising a high-frequency signal transmission device according to any one of claims 1 to 4.

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