JP7794037B2 - electronic equipment - Google Patents

Description

This disclosure relates to an electronic device equipped with an antenna for wireless communication.

In recent years, wireless communication technologies such as wireless LAN and Bluetooth (registered trademark), which allow information exchange through the transmission and reception of radio waves without the use of cables, have become widespread, and electronic devices with built-in wireless communication antennas have been put into practical use. It is also known to provide a detachable antenna on the exterior of an electronic device in order to add wireless communication functionality with high reception sensitivity (see, for example, Reference 1).

Japanese Patent Application Laid-Open No. 2003-243914

Patent Document 1 describes a detachable patch antenna that can be attached to an antenna terminal on the exterior of an electronic device, and that reception sensitivity can be increased by aligning the patch antenna with the direction from which the radio waves to be received are coming. However, when using multiple electronic devices side by side, or when placing other electronic devices near the antenna, there is an issue in that reception sensitivity to noise generated by the other electronic devices also increases.

This disclosure has been made in response to the above-mentioned issues. It aims to provide an electronic device that suppresses the effects of noise generated by other surrounding electronic devices and has wireless communication functions with high reception sensitivity.

The electronic device according to the present disclosure comprises a first circuit board having a first surface with a light-emitting element and a second surface opposite to the first surface with an antenna; a second circuit board with a main control circuit; a first inter-board connecting member connecting the first circuit board and the second circuit board; and a metal casing formed of a metal material, housing the first circuit board and the second circuit board, and including a first surface with an opening, wherein the first surface of the first circuit board is arranged adjacent to the first surface along the first surface of the metal casing, and the light-emitting element and the antenna are arranged to overlap with the opening in a plan view from a first direction perpendicular to the first surface.

Electronic devices according to the present disclosure can suppress the effects of surrounding noise and have wireless communication functions with high reception sensitivity.

1 is a circuit block diagram showing a configuration of an electronic device 100 according to a first embodiment. 1 is a perspective view showing the appearance of an electronic device 100 according to a first embodiment. 3 is a cross-sectional view taken along the line AA shown in FIG. 2. 3 is a cross-sectional view taken along the line BB in FIG. 2. FIG. 2 is a front view showing the appearance of a circuit board unit 30 according to the first embodiment. FIG. 2 is a perspective view showing the appearance of a circuit board unit 30 according to the first embodiment. FIG. 5 is an enlarged view of an area C shown in FIG. 4 . 10 is a graph showing the relationship between the electric field strength of a plane electric field wave, the longitudinal length L of the opening 5, and the distance D between the opening antennas. FIG. 10 is a perspective view showing the appearance of an electronic device 200 according to a second embodiment. 10 is a cross-sectional view taken along the line J-J shown in FIG. 9. 10 is a cross-sectional view taken along the line KK in FIG. 9. FIG. 10 is a front view showing a circuit board unit 40 according to a second embodiment. FIG. 10 is a cross-sectional view showing an electronic device 201 according to a modification of the second embodiment. FIG. 10 is a front view showing a circuit board unit 41 in a modified example of the second embodiment.

Embodiment 1.
1 is a circuit block diagram showing the configuration of electronic device 100 according to embodiment 1. Electronic device 100 has a first circuit board 10 and a second circuit board 20, which are housed inside metal housing 1.

The first circuit board 10 includes a display circuit 11, a setting circuit 12, a wireless circuit 13, and an antenna 14. The second circuit board 20 includes a main control circuit 21, a communication circuit 22, and an external connector 23. The first circuit board 10 and the second circuit board 20 are connected by an inter-board connecting member 2 such as an inter-board connector. Here, the arrows in FIG. 1 indicate the direction in which signals are exchanged. The inter-board connecting member 2 is the first inter-board connecting member described in the claims.

Here, the electronic device 100 in embodiment 1 is, for example, a PCL (Programmable Logic Controller), a servo amplifier, or an inverter. However, the electronic device 100 is not limited to these electronic devices. The electronic device 100 also has wireless communication capabilities.

The display circuit 11 provided on the first circuit board 10 includes a light-emitting element 15 such as an LED (Light Emitting Diode). The display circuit 11 may also include a current-limiting resistor that limits the current flowing through the light-emitting element 15, and an LED driver to stably supply current to the LED light-emitting element 15. Here, the display circuit 11 uses the light of the light-emitting element 15 to visually indicate to the user, for example, the operating status of the electronic device 100, the communication status between the electronic device 100 and devices connected to it, and the operating status of devices connected to the electronic device 100. The light-emitting element 15 will be described later.

The setting circuit 12 includes an input unit such as a piano switch or rotary switch. The input unit serves as an external input 3, allowing the user to set the operation and processing of the electronic device 100 via the input unit. It is not necessary to include both the display circuit 11 and the setting circuit 12; it is sufficient to include at least one of the display circuit 11 or the setting circuit 12. The input unit will be explained later.

The radio circuit 13 includes, for example, a control circuit with a wireless communication controller IC, a power supply circuit, an oscillator circuit or PLL circuit that generates a carrier wave, an AD conversion circuit or DA conversion circuit, a modulation circuit, a filter, a mixer, an amplifier, or a matching circuit, and converts digital signals to modulated waves and modulated waves to digital signals between the main control circuit 21 and the antenna 14. Here, the radio circuit 13 may be provided on the second circuit board 20 instead of the first circuit board 10.

The antenna 14 functions as an energy converter that transmits electrical signals into space as radio waves and receives radio waves in space as electrical signals. To efficiently supply power to the antenna 14, it is recommended that a matching circuit provided in the radio circuit 13 be used to match the input impedance of the antenna 14 with the impedance of the signal source.

The main control circuit 21 provided on the second circuit board 20 is composed of a control IC, such as a CPU (Central Processing Unit), FPGA (Field Programmable Gate Array), or SoC (System on a Chip), and may also include a transmitter circuit, reset circuit, interrupt circuit, main memory, etc. The main control circuit 21 is responsible for the calculation, storage, and control of the electronic device 100. It also functions as a circuit that controls the radio circuit 13.

Here, communication between the main control circuit 21 and the radio circuit 13 is performed via an interface (I/F) such as serial communication SPI (Serial Peripheral Interface) or UART (Universal Asynchronous Receiver/Transmitter).

Furthermore, the electronic device 100 in embodiment 1 is not limited to the circuits shown in FIG. 1, and may include power supply circuits, inverter circuits, analog/digital input/output circuits, video input/output circuits, audio input/output circuits, filter circuits, isolation circuits, surge static electricity protection circuits, and other circuits depending on the functions required of the electronic device 100.

Next, we will explain the circuit operation of electronic device 100, which transmits information to an external electronic device using its wireless communication function. The digital signal indicating the information to be transmitted is output as an electrical signal from main control circuit 21, and is modulated to a carrier frequency in accordance with the wireless standard by wireless circuit 13. The digital signal modulated to the carrier frequency is then converted from an electrical signal to radio waves by antenna 14, and the information is transmitted as radio waves to the external electronic device.

Next, we will explain the circuit operation in which electronic device 100 receives information transmitted by an external electronic device using its wireless communication function. Radio waves indicating the information transmitted by the external electronic device are received by antenna 14, which then converts the radio waves into an electrical signal. The electrical signal converted by antenna 14 is then digitized by wireless circuit 13 and transmitted as digital information to main control circuit 21.

Here, the carrier frequency according to the wireless standard is the 2.4 GHz band used for wireless LAN and Bluetooth (registered trademark). However, it may also be a carrier frequency according to other wireless standards, such as the 3.7 GHz band, 4.5 GHz band, 5 GHz band, or 28 GHz band. Furthermore, in order to support multiple wireless standards, multiple radio circuits 13 and multiple antennas 14 may be provided.

Furthermore, in addition to wireless communication capabilities, electronic device 100 also has wired communication capabilities such as USB (Universal Serial Bus) and wired LAN. For example, using external connector 23 and communication circuit 22, it is possible to send and receive information with external electronic devices. External connector 23 is, for example, a USB connector or an RJ45 connector. A detailed description of the wired communication capabilities will be omitted here.

Figure 2 is a perspective view showing the appearance of electronic device 100 in embodiment 1. Figure 3 shows a cross-sectional view of electronic device 100 shown in Figure 2 taken along line A-A. Figure 4 shows a cross-sectional view of electronic device 100 shown in Figure 3 taken along line B-B. Figure 5 is a front view showing the configuration of circuit board unit 30 in which first circuit board 10 and second circuit board 20 are connected by inter-board connecting member 2. Figure 6 is a perspective view showing the configuration of circuit board unit 30.

As shown in Figures 2 to 4, electronic device 100 in embodiment 1 includes a circuit board unit 30 in which a first circuit board 10 and a second circuit board 20 are connected using an inter-board connecting member 2, and a metal housing 1 that houses circuit board unit 30. Metal housing 1 has multiple surfaces including a first surface 4, and an opening 5 is provided on first surface 4 of metal housing 1. Here, opening 5 in metal housing 1 is shown as a single opening, but this is not limited to this. In other words, opening 5 in metal housing 1 may be composed of multiple openings.

When viewed from a first direction (Y direction) perpendicular to the first surface 4, the opening 5 is arranged to overlap with the light-emitting element 15 provided on the first circuit board 10, the input section provided on the first circuit board 10, or both the light-emitting element 15 and the input section. The input section is not shown here. Furthermore, when viewed from a first direction perpendicular to the first surface 4, the opening 5 is arranged to overlap with at least a portion of the antenna 14 provided on the first circuit board 10.

Also, as shown in FIG. 2, a hole is provided on the first surface 4 of the metal housing 1 to match the size of the external connector 23 provided on the second circuit board 20 so that it overlaps with the external connector 23 in the first direction, and the external connector 23 is fixed so that a portion of the external connector 23 is exposed through the hole in the metal housing. Here, the material of the external connector 23 may be either metallic or non-metallic.

The opening 5 provided in the metal casing 1 may be filled with a dielectric 6. The dielectric 6 may be, for example, resin or glass. Furthermore, it is preferable to use an insulator with a relative dielectric constant of 1 or more as the dielectric 6. By increasing the relative dielectric constant of the insulator, the wavelength of the radio waves can be shortened, and even if the opening 5 is small, the penetration depth of the radio waves into the metal casing 1 can be increased, making it easier to send and receive wirelessly. Furthermore, by filling the opening 5 with a dielectric 6 such as resin or glass, dustproofing and waterproofing performance can be improved.

The metal housing 1 is made of a metal material such as copper, iron, aluminum, an iron alloy, or an aluminum alloy. The thickness of the metal housing 1 is 0.1 mm or more, and preferably 1 mm or more. The metal housing 1 may be molded as a single piece, or may be formed by combining multiple metal plates.

The electrical conductivity of the metal housing 1 is preferably 1.0×10 ⁶ [S/m] or more, and more preferably 1.0×10 ⁷ [S/m] or more. In an installation environment of the electronic device 100 that requires magnetic shielding at frequencies of 50/60 Hz, it is preferable to use a magnetic metal with high electrical conductivity, such as SPCC, which is mainly composed of iron, or SUS430.

Furthermore, the thermal conductivity of the metal casing 1 is 1.0 W/(m·K) or more, and preferably 10.0 W/(m·K) or more. The metal casing 1 may also be equipped with piping for passing cooling water inside, or heat dissipation fins to promote heat dissipation to the atmosphere. The metal casing 1 may also be in contact with an external cooling body to dissipate heat through heat transfer. The external cooling body is not shown here.

The potential of the metal casing 1 is set according to the performance required of the electronic device 100. For example, it is set to the same potential as the reference ground of the first circuit board 10 and the second circuit board 20. However, this is not limiting, and the potential of the metal casing 1 may also be set to the same potential as the frame ground or earth.

In this way, using the metal housing 1 as the housing for the electronic device 100 can prevent electric shock and burns to the user, and protect the circuit board unit 30 housed within the electronic device 100 from dust and oil droplets that may occur in the installation environment. Furthermore, using the metal housing 1 can improve noise resistance, vibration resistance, impact resistance, and heat dissipation. In particular, since the metal housing 1 is mostly covered with metal, it functions as a shield against electromagnetic noise, making it possible to block external noise that may reach the electronic device 100 in the installation environment.

Furthermore, by DC- or AC-coupling the reference grounds of the metal casing 1 and the circuit board unit 30 therein, it is possible to reduce the impedance of the reference ground, thereby improving the EMC (Electromagnetic Compatibility) performance of the electronic device 100.

As shown in Figures 3 and 4, in embodiment 1, a circuit board unit 30 consisting of a first circuit board 10 and a second circuit board 20 is housed within a metal housing 1. The first circuit board 10 includes a display circuit 11, a wireless circuit 13, and an antenna 14 on a printed circuit board 7. The first circuit board 10 is disposed adjacent to the first face 4 of the metal housing 1, and has a first surface 16 facing the first face 4 and a second surface 17 on the opposite side in a first direction, which is perpendicular to the first face 4.

A light-emitting element 15, such as an LED, is provided on the first surface 16 of the first circuit board 10. The first surface 16 of the first circuit board 10 is disposed adjacent to and along the first face 4, and light from the light-emitting element 15 is emitted to the outside via a dielectric 6 disposed in the opening 5. The first surface 16 may also be provided with an input unit instead of the light-emitting element 15, allowing a user to set the operation and processing of the electronic device 100 via the input unit through the opening 5. Furthermore, the first surface 16 of the first circuit board 10 may also be provided with both the light-emitting element 15 and the input unit. The input unit is not shown here.

A radio circuit 13 and an antenna 14 are provided on the second surface 17 of the first circuit board 10. Here, a configuration in which the radio circuit 13 and antenna 14 are provided on the first circuit board 10 is shown, but it is also possible to provide only the antenna 14 on the second surface 17 of the first circuit board 10, with the radio circuit 13 provided on the second circuit board 20. Also, a wireless communication module in which the radio circuit 13 and antenna 14 are integrally formed may be provided on the second surface 17.

In addition, the antenna 14 may not be a single antenna but may be composed of multiple antennas, each of which may be used for wireless LAN and Bluetooth. Furthermore, the antenna 14 may be given directionality so that radio waves for wireless communication can be efficiently transmitted and received through the opening 5 in the metal casing 1.

The second circuit board 20 has a third surface 24 on which the main control circuit 21 is provided, and a fourth surface 25 opposite the third surface. The second circuit board 20 is arranged, for example, along the second surface 9, which is a surface perpendicular to the first surface 4 of the metal casing 1. In other words, the second circuit board 20 is arranged adjacent to the second surface 9, which is a surface perpendicular to the first surface 4 of the metal casing 1, and the fourth surface 25 of the second circuit board 20 is arranged opposite the second surface 9.

The second circuit board 20 includes a main control circuit 21, a communication circuit 22, and an external connector 23 on a printed circuit board 8. Here, the main control circuit 21 and the communication circuit 22 may be provided on the second circuit board 20 as a single main control IC. Furthermore, the second circuit board 20 includes an external connector 23 adjacent to the first surface 4 of the metal casing 1. Here, the external connector 23 is provided so that a portion of it is exposed from the metal casing 1. As shown in Figures 3 to 6, the second circuit board 20 is composed of a single printed circuit board 8, but is not limited to this and may be composed of multiple printed circuit boards 8 depending on the circuit scale.

The first circuit board 10 is connected to the second circuit board 20 using an inter-board connection member 2 such as an inter-board connector. The inter-board connection member 2 is not limited to an inter-board connector; electrodes on the first circuit board 10 and the second circuit board 20 may be connected by soldering or by a cable.

The inter-board connection member 2 is an interface that electrically connects the first circuit board 10 and the second circuit board 20, and performs signal transmission, power supply, common grounding, and other functions via the inter-board connection member 2. Multiple inter-board connection members 2 may be provided, and one may be provided for each purpose, such as for signal connection, power supply connection, or ground connection. Furthermore, metal spacers or metal screws, for example, may be used as the inter-board connection member 2 for ground connection. This improves the strength of the connection and reduces the impedance between the grounds of the first circuit board 10 and the second circuit board 20.

The printed circuit boards 7 and 8 used in the first circuit board 10 and the second circuit board 20 are made of materials such as glass fiber reinforced epoxy resin, phenolic resin, polyphenylene sulfide (PPS), and polyether ether ketone (PEEK). The printed circuit boards may also be made of ceramics such as aluminum oxide, aluminum nitride, and silicon carbide.

Furthermore, the printed circuit boards 7 and 8 used in the first circuit board 10 and the second circuit board 20 may include two or more conductor layers that form circuit wiring, and the circuit wiring may be formed on the surface and inside the printed circuit boards 7 and 8. The circuit wiring is formed from a conductive material, such as copper, nickel, gold, aluminum, silver, tin, or alloys thereof. The thickness of the circuit wiring is 1 μm or more and 2000 μm or less. Illustration of the circuit wiring is omitted here.

In the electronic device 100 of embodiment 1, the first circuit board 10 is located inside the metal housing 1, adjacent to the first surface 4 of the metal housing 1, with the first surface 16 aligned along the first surface 4. The antenna 14 is also provided on the second surface 17 opposite the first surface 16, and is arranged so that at least a portion of the antenna 14 overlaps with an opening 5 provided in the metal housing 1 in the first direction (Y direction), which is perpendicular to the first surface 4.

The shorter the distance of the antenna 14 from the opening 5 in the first direction, the higher the reception sensitivity of the antenna 14 for wireless communication with external electronic devices. Furthermore, as shown in Figures 3 to 6, in the electronic device 100 of embodiment 1, the antenna 14 is provided on the second surface 17 of the first circuit board 10, and at least the printed circuit board 7 of the first circuit board 10 is provided between the antenna 14 and the opening 5 of the metal housing 1.

Here, the circuit wiring provided on the printed circuit board 7 of the first circuit board 10 is made of a conductive material such as copper foil, which may block some of the radio waves used for wireless communication with external electronic devices, degrading transmission and reception performance. Therefore, by reducing the amount of circuit wiring provided on the printed circuit board 7, it is possible to prevent deterioration of transmission and reception performance. In other words, by reducing the wiring ratio of the circuit wiring provided on the printed circuit board 7, it is possible to prevent deterioration of transmission and reception performance.

For example, the wiring ratio of the circuit wiring on the printed circuit board 7 of the first circuit board 10 is lower than the wiring ratio of the printed circuit board 8 of the second circuit board 20 that includes the main control circuit 21. This makes it possible to prevent deterioration of transmission and reception performance due to the radio waves used for wireless communication being blocked by the circuit wiring.

Furthermore, by not providing circuit wiring in the area of the printed circuit board 7 that overlaps with the antenna 14 when viewed in a plan view in the first direction perpendicular to the first surface 4 of the metal casing 1, radio waves used for wireless communication are not blocked by the circuit wiring, and deterioration of transmission and reception performance can be suppressed. Furthermore, by not providing a light-emitting element 15 or an input unit in the area of the printed circuit board 7 that overlaps with the antenna 14 when viewed in a plan view in the first direction, deterioration of transmission and reception performance can be suppressed.

As shown in Figures 3 and 4, electronic device 100 in embodiment 1 has opening 5 in metal casing 1. Opening 5 has, for example, a rectangular shape, and the longer its longitudinal length, or long side length, the easier it is for radio waves used for wireless communication to penetrate into metal casing 1, and the higher the radio wave transmission and reception performance of antenna 14. In other words, the longer the longitudinal length of opening 5, or long side length, the better radio wave transmission and reception performance can be maintained even if the distance between antenna 14 and opening 5 in the first direction is greater. Here, the short side length of opening 5 only needs to be 1 mm or more, and the short side length of opening 5 has little effect on radio wave transmission and reception performance.

The shape of the opening 5 is shown as a rectangle as an example, but it is not limited to this and may be an oval or a rectangle with rounded corners. Furthermore, while Figures 3 and 4 show the opening 5 in the metal housing 1 as a single opening, this is not limited to this. In other words, the opening 5 in the metal housing 1 may be made up of multiple openings.

Using Figures 7 and 8, we will explain the results of a simulation in which a 2.4 GHz electric field plane wave, used in wireless LAN and Bluetooth, is propagated through the metal housing 1 that constitutes the electronic device 100. Figure 7 is an enlarged view of area C surrounded by a dashed line in Figure 4. The dielectric 6 filled in the opening 5 is not shown here.

As shown in Figure 7, the longitudinal length of the opening 5 in the metal casing 1 is defined as L, which is the length of the long side of the opening 5. Furthermore, let E (two-dot dash line) be an imaginary plane that includes the first surface 4 of the metal casing 1 and the opening 5 provided in the first surface, and let D be the distance between the opening antennas, which is the distance from the imaginary plane E to the antenna 14 in the first direction (Y direction) perpendicular to the first surface 4 of the metal casing 1. Here, if the opening 5 in the metal casing 1 is composed of multiple openings, let L be the longitudinal length of each opening. Here, the longitudinal length L of the opening 5 is set so that the opening 5 fits within the first surface 4 of the metal casing 1.

Figure 8 is a graph showing the relationship between the electric field strength of a 2.4 GHz band electric field plane wave, the longitudinal length L (the length of the long side of the opening 5), and the distance D between the opening antennas. Dashed line F indicates an electric field strength of 70%, and region G, whose end is dashed line F, indicates an area where the electric field strength is 70% or higher. Furthermore, dotted line H is a straight line indicating L/D = 1. This shows that region G overlaps with the area where L/D ≥ 1 is satisfied. In other words, when the longitudinal length L of the opening 5 and the distance D between the opening antennas satisfy L/D ≥ 1, the electric field strength at antenna 14 is 70% or higher.

Here, if the electric field strength at the antenna 14 is 70% or higher, good radio wave transmission and reception performance can be achieved via wireless communication. In other words, by arranging the opening 5 in the metal casing 1 and the antenna 14 so that L/D≧1 is satisfied, an electronic device 100 with wireless communication functionality and high reception sensitivity can be obtained.

Next, the effects of the electronic device 100 in embodiment 1 will be described. The electronic device 100 has a first circuit board 10 and a second circuit board 20, which are housed inside a metal housing 1. The first circuit board 10 has a first surface 16 that includes a light-emitting element 15 of the display circuit 11 and an input section of the setting circuit 12, or the light-emitting element 15 and the input section. The first circuit board 10 also has an antenna 14 on a second surface 17 opposite the first surface 16.

By using a metal housing 1 as the housing for the electronic device 100 and storing the first circuit board 10 and second circuit board 20 inside the metal housing 1, it is possible to prevent electric shock and burns to the user, and to protect the circuit board unit 30 stored inside the electronic device 100 from dust and oil droplets that may occur in the installation environment. Furthermore, by using the metal housing 1, it is possible to improve noise resistance, vibration resistance, impact resistance, and heat dissipation. In particular, since the metal housing 1 is mostly covered with metal, it functions as a shield against electromagnetic noise, making it possible to block external noise that may reach the electronic device 100 in the installation environment.

Furthermore, the first circuit board 10 is arranged so that the first surface 16 is adjacent to and along the first face 4 of the metal housing 1. In other words, the first circuit board 10 is arranged so that it is adjacent to the first face 4 of the metal housing 1 and the first surface 16 faces the first face 4.

Here, the opening 5 of the metal housing 1 is arranged to overlap with the light-emitting element 15 provided on the first circuit board 10, the input section provided on the first circuit board 10, or the light-emitting element 15 and the input section, when viewed in a plan view from the first direction (Y direction), which is a direction perpendicular to the first surface 4. Furthermore, the opening 5 is arranged to overlap with at least a portion of the antenna 14 provided on the first circuit board 10, when viewed in a plan view from the first direction. Here, the light-emitting element 15, the input section, or the light-emitting element 15 and the input section are arranged closer to the opening 5 than the antenna 14.

Furthermore, in the electronic device 100 of embodiment 1, the longitudinal length L of the opening 5 in the metal casing 1 and the aperture-to-antenna distance D, which is the distance from the antenna 14 to an imaginary plane E including the first surface 4 and the opening 5 provided on the first surface in a first direction (Y direction) perpendicular to the first surface 4 of the metal casing 1, are set so that L/D≧1, thereby achieving good radio wave transmission and reception performance via wireless communication.

This allows for the electronic device 100 to be equipped with wireless communication functions that suppress the effects of surrounding noise and have high reception sensitivity.

Embodiment 2.
Next, an electronic device 200 according to a second embodiment will be described. In the second embodiment, only the configuration differences from the first embodiment will be described. The same or corresponding configurations as those in the first embodiment will be designated by the same reference numerals, and the description thereof will be omitted. The electronic device 200 differs from the electronic device 100 according to the first embodiment in the configuration of the first circuit board 10 and the arrangement of the first circuit board 10 within the metal housing 1.

Figure 9 is a perspective view showing the appearance of electronic device 200 in embodiment 2. Figure 10 shows a cross-sectional view of electronic device 200 shown in Figure 9 taken along line J-J. Figure 11 shows a cross-sectional view of electronic device 200 shown in Figure 9 taken along line K-K. Figure 12 is a front view showing the configuration of circuit board unit 40 in which first circuit board 10 and second circuit board 20 are connected by inter-board connecting member 2A.

As shown in Figures 9 to 11, electronic device 200 in embodiment 2 includes a circuit board unit 40 in which a first circuit board 10 and a second circuit board 20 are connected by an inter-board connecting member 2A, and a metal housing 1 that houses circuit board unit 40. Metal housing 1 has multiple surfaces including a first surface 4, and first surface 4 of metal housing 1 has an opening 5.

As shown in Figures 9 to 11, the first circuit board 10 has a light-emitting element 15, a wireless circuit 13, and an antenna 14 on a printed circuit board 7, and has a first surface 16 and a second surface 17 opposite the first surface 16. The second circuit board 20 has a main control circuit 21, a communication circuit 22, and an external connector 23 on a printed circuit board 8, and has a third surface 24 and a fourth surface 25 opposite the third surface 24. Here, the circuit board unit 40 is arranged so that the second surface 17 of the first circuit board 10 and the third surface 24 of the second circuit board 20 face each other, and are connected by an inter-board connecting member 2A.

The first circuit board 10 is arranged so that the first surface 16 and the second surface 17 are aligned along a first direction (Y direction) that is perpendicular to the first face 4 of the metal casing 1. Furthermore, the first circuit board 10 has an edge 18 connecting the first surface 16 and the second surface 17, with at least a portion of the edge 18 being positioned adjacent to the opening 5.

The second circuit board 20 is arranged, for example, along the second surface 9, which is a surface perpendicular to the first surface 4 of the metal housing 1. In other words, the second circuit board 20 is arranged adjacent to the second surface 9, which is a surface perpendicular to the first surface 4 of the metal housing 1, and the fourth surface 25 of the second circuit board 20 is arranged facing the second surface 9.

Light-emitting elements 15, such as LEDs, of the display circuit 11 are provided on the first surface 16 of the first circuit board 10. The light-emitting elements 15 of the display circuit 11 may be replaced with an input section of the setting circuit 12. Furthermore, both the light-emitting elements 15 and the input section may be provided. The light-emitting elements 15, the input section, or both the light-emitting elements 15 and the input section are arranged to overlap the opening 5 in a plan view from a first direction (Y direction) perpendicular to the first surface 4.

Here, the light-emitting element 15 is positioned near the edge 18 adjacent to the opening 5, and light from the light-emitting element 15 is emitted to the outside through the dielectric 6 provided in the opening 5. The input unit is also positioned near the edge 18 adjacent to the opening 5, and the user can set the operation and processing of the electronic device 100 via the input unit through the opening 5. The input unit is not shown here.

A radio circuit 13 and an antenna 14 are provided on the second surface 17 of the first circuit board 10. While the configuration shown here includes the radio circuit 13 and antenna 14 on the first circuit board 10, it is also possible to provide only the antenna 14 on the second surface 17 of the first circuit board 10, with the radio circuit 13 on the second circuit board 20. Alternatively, a wireless communication module in which the radio circuit 13 and antenna 14 are integrally formed may be provided on the second surface 17. Here, at least a portion of the antenna 14 is arranged to overlap the opening 5 when viewed from a first direction, which is perpendicular to the first surface 4 of the metal housing 1.

The closer the antenna 14 is to the opening 5, the better, and it is best to place it near the edge of the first circuit board 10 adjacent to the opening 5. In the electronic device 100 of embodiment 2, the first circuit board 10 is placed so that the first surface 16 and second surface 17 of the first circuit board 10 are aligned in a direction perpendicular to the first face 4 of the metal casing 1, so the antenna 14 can be placed closer to the opening 5 than in the electronic device 100 of embodiment 1.

Furthermore, as in embodiment 1, the electronic device 200 of embodiment 2 is configured so that the longitudinal length L of the opening 5 in the metal casing 1 and the aperture-antenna distance D, which is the distance from the antenna 14 to an imaginary plane E that includes the first surface 4 of the metal casing 1 and the opening 5 provided in the first surface in a first direction (Y direction) perpendicular to the first surface, satisfy L/D≧1.

Figure 13 shows the same cross-sectional view as Figure 11 of embodiment 2, but of an electronic device 201 according to a modification of embodiment 2, in which an inter-board connecting member 2B is added to the inter-board connecting member 2A connecting the first circuit board 10 and the second circuit board 20. Figure 14 is a front view showing the appearance of a circuit board unit 41 according to a modification of embodiment 2. The inter-board connecting member 2A is the first inter-board connecting member described in the claims, and the inter-board connecting member 2B is the second inter-board connecting member described in the claims.

As shown in Figures 13 and 14, electronic device 201 in a variation of embodiment 2 uses inter-board connecting member 2B in addition to inter-board connecting member 2A to connect first circuit board 10 and second circuit board 20. For example, inter-board connecting member 2A can be used for signals and power, and inter-board connecting member 2B can be used for ground connection, and different inter-board connecting members 2 can be provided for different purposes. Furthermore, metal spacers or metal screws, for example, can be used for ground connection. This can improve the strength of the connection and reduce the impedance between the grounds of first circuit board 10 and second circuit board 20.

Next, the effects of electronic device 200 in embodiment 2 and electronic device 201 in a modified example of embodiment 2 will be described. In electronic device 200 and electronic device 201, first circuit board 10 is positioned so that first surface 16 and second surface 17 of first circuit board 10 are aligned in a direction perpendicular to first face 4 of metal casing 1. As a result, antenna 14 is positioned near edge 18 of first circuit board 10 adjacent to opening 5, allowing antenna 14 to be positioned closer to opening 5 than in electronic device 100 in embodiment 1.

This makes it possible to obtain electronic device 200 or electronic device 201 equipped with wireless communication functionality with higher reception sensitivity than electronic device 100 of embodiment 1.

1 Metal housing, 2, 2A, 2B Inter-board connecting member, 3 External input, 4 First surface, 5 Opening, 6 Dielectric, 7, 8 Printed circuit board, 9 Second surface, 10 First circuit board, 11 Display circuit, 12 Setting circuit, 13 Wireless circuit, 14 Antenna, 15 Light-emitting element, 16 First surface, 17 Second surface, 18 Edge portion, 20 Second circuit board, 21 Main control circuit, 22 Communication circuit, 23 External connector, 24 Third surface, 25 Fourth surface, 30, 40, 41 Circuit board unit, 100, 200, 201 Electronic device.

Claims (10)

a first circuit board having a first surface with a light emitting element thereon and a second surface opposite the first surface with an antenna;
a second circuit board including a main control circuit;
a first inter-board connecting member that connects the first circuit board and the second circuit board;
a metal housing formed of a metal material, housing the first circuit board and the second circuit board, and including a first surface having an opening;
the first circuit board is disposed such that the first surface is adjacent to and along the first surface of the metal housing;
The electronic device is configured such that the light-emitting element and the antenna overlap with the opening in a plan view from a first direction perpendicular to the first surface. a first circuit board having a first surface provided with an input section capable of receiving an input from an external device, and a second surface opposite to the first surface provided with an antenna;
a second circuit board including a main control circuit;
a first inter-board connecting member that connects the first circuit board and the second circuit board;
a metal housing formed of a metal material, housing the first circuit board and the second circuit board, and including a first surface having an opening;
the first circuit board is disposed such that the first surface is adjacent to and along the first surface of the metal housing;
The electronic device, wherein the input unit and the antenna are arranged to overlap with the opening in a plan view from a first direction perpendicular to the first surface. a first circuit board having a first surface with a light emitting element thereon and a second surface opposite the first surface with an antenna;
a second circuit board including a main control circuit;
a first inter-board connecting member that connects the first circuit board and the second circuit board;
a metal housing that houses the first circuit board and the second circuit board and includes a first surface having an opening;
the first circuit board is disposed along the second circuit board with the second surface facing the second circuit board;
The electronic device is configured such that the light-emitting element and the antenna overlap with the opening in a plan view from a first direction perpendicular to the first surface. a first circuit board having a first surface provided with an input section capable of receiving an input from an external device, and a second surface opposite to the first surface provided with an antenna;
a second circuit board including a main control circuit;
a first inter-board connecting member that connects the first circuit board and the second circuit board;
a metal housing that houses the first circuit board and the second circuit board and includes a first surface that has an opening,
the first circuit board is disposed along the second circuit board with the second surface facing the second circuit board;
The electronic device, wherein the input unit and the antenna are arranged to overlap with the opening in a plan view from a first direction perpendicular to the first surface. The antenna is
5. The electronic device according to claim 1, wherein a longitudinal length L of the opening and an aperture-antenna distance D, which is a distance from the opening to the antenna, are set so as to satisfy L/D≧1. the second circuit board has a third surface including the main control circuit and a fourth surface opposite the third surface;
the metal housing has a second surface perpendicular to the first surface;
The electronic device according to claim 3 , wherein the fourth surface of the second circuit board is disposed along and adjacent to the second surface. The electronic device described in any one of claims 1 to 6, further comprising a second inter-board connection member connecting the first circuit board and the second circuit board. The electronic device described in any one of claims 1 to 7, wherein the wiring ratio of the circuit wiring of the first circuit board is lower than the wiring ratio of the circuit wiring of the second circuit board. The electronic device described in any one of claims 1 to 8, wherein the opening is filled with an insulator having a relative dielectric constant of 1 or more. The electronic device according to claim 1 , wherein the first surface and the first face are opposed to each other.