Patent Publication Number: US-2011068994-A1

Title: Communication module, communication apparatus

Description:
BACKGROUND 
     1. Field 
     The present application relates to a communication module. The present application relates to a communication apparatus including the communication module. 
     2. Description of Related Art 
     In recent years, an information device such as a notebook computer provided with a wireless communication system is becoming mainstream. The wireless communication system is, e.g., a system that is connected to the network by wireless such as LAN (local area network) or a system that is connected to an access point by wireless such as Bluetooth (registered trademark). In particular, an information device that has a plurality of types of wireless communication systems and selectively can perform wireless communications has been developed. Examples of the wireless communication system incorporated into the information device include a wireless LAN, a wireless WAN (wide area network), and the Bluetooth. When these wireless communication systems are incorporated into a single information device, the transmission frequency band and the reception frequency band of radio generally differ depending on the type of wireless communication system. However, some wireless communication systems use the same frequency band. For example, both the wireless LAN in conformity with the IEEE 802.11 standard and the Bluetooth use the 2.4 GHz band. 
     In the case where the information device includes a plurality of antenna elements that transmit and receive radio waves in the same frequency band, isolation between the antenna elements is degraded if the antenna elements are located close to each other. Thus, the transmission and reception characteristics of each of the antenna elements may be degraded. To suppress the degradation of the isolation, the antenna elements can be spaced away from each other. However, this leads to an increase in size of the information device. As a technique of improving the isolation between the antenna elements without increasing the size of the information device, a configuration has been proposed in which a ground pattern is provided in the vicinity of the antenna elements. 
     JP 2004-328717 A discloses a diversity antenna with a layered structure in which a substrate having a plurality of flat antenna elements and a substrate having a hybrid pattern that switches the antenna elements are formed via a substrate having a ground pattern. 
     However, the ground pattern of JP 2004-328717 A is provided on the substrate that is interposed between the substrate having the hybrid pattern and the substrate having the antenna elements. Such a ground pattern is less effective in suppressing mutual interference between transmitting/receiving surfaces of the respective flat antenna elements disposed on the substrate. Consequently, an improvement in the isolation between the transmitting/receiving surfaces of the antenna elements cannot be expected much. 
     SUMMARY 
     A communication module of the present application includes a plurality of antenna elements, each of which has a transmitting/receiving surface that transmits and receives radio signals, and an isolation member that is provided between the plurality of antenna elements and has a ground potential to suppress electrical interference between the transmitting/receiving surfaces of the respective antenna elements. 
     A communication apparatus of the present application includes a communication module. The communication module includes a plurality of antenna elements, each of which has a transmitting/receiving surface that transmits and receives radio signals, and an isolation member that is provided between the plurality of antenna elements and has a ground potential to suppress electrical interference between the transmitting/receiving surfaces of the respective antenna elements. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a notebook computer that is an example of a communication apparatus according to an embodiment. 
         FIG. 2  is a plan view of a first case of the notebook computer. 
         FIG. 3A  is a plan view of a communication module according to an embodiment. 
         FIG. 3B  is a cross-sectional view taken along the line Z-Z in  FIG. 3A . 
         FIG. 4A  is a plan view showing the main portion of a communication apparatus incorporating a communication module according to an embodiment. 
         FIG. 4B  is a cross-sectional view taken along the line Z-Z in  FIG. 4A . 
         FIG. 5A  is a plan view showing a modified example of a communication module. 
         FIG. 5B  is a cross-sectional view taken along the line Z-Z in  FIG. 5A . 
         FIG. 6A  is a plan view showing a modified example of a communication module. 
         FIG. 6B  is a cross-sectional view taken along the line Z-Z in  FIG. 6A . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     The communication module or the communication apparatus of this embodiment includes a plurality of antenna elements, each of which has a flat transmitting/receiving surface that transmits and receives radio signals, and an isolation member that has a flat surface, is provided between the transmitting/receiving surfaces of the plurality of antenna elements, and has a ground potential to suppress electrical interference between the plurality of antenna elements. 
     In the communication module or the communication apparatus of this embodiment, the plurality of antenna elements may be configured so that frequency bands of the radio signals transmitted and received by the antenna elements are the same. With this configuration, even if the isolation between the antenna elements that can transmit and receive radio waves in the same frequency band is degraded relatively significantly, the degradation of the isolation can be suppressed. 
     The communication module or the communication apparatus of this embodiment further may include a substrate on which the plurality of antenna elements and the isolation member are mounted. The plurality of antenna elements and the isolation member may be located on the same face of the substrate. This configuration can suppress the degradation of the isolation between the antenna elements. Moreover, since the number of substrates is reduced, this configuration also can reduce the cost and the man-hours required to incorporate the substrates into the communication apparatus. Furthermore, the communication module and the communication apparatus can have a small size. 
     The communication module or the communication apparatus of this embodiment further may include a substrate on which the plurality of antenna elements and the isolation member are mounted. The isolation member may be located in at least one location selected from a first surface of the substrate on which the plurality of antenna elements are mounted, a second surface of the substrate that is on the opposite side of the first surface, and a region between the first surface and the second surface of the substrate. This configuration can increase the area of the ground pattern without increasing the size of the communication module. Since the area of the ground pattern can be increased, the effect of suppressing the degradation of the isolation can be improved further. 
     Embodiment 1 
       FIG. 1  is a perspective view showing the appearance of a communication apparatus of this embodiment.  FIG. 1  illustrates a notebook computer as an example of the communication apparatus.  FIG. 2  is a plan view of a first case of the notebook computer of this embodiment. This embodiment describes the notebook computer having a wireless communication system as an example of the communication apparatus. However, any apparatuses such as a portable telephone, an electronic game machine, and medical equipment may be used as long as they have at least a plurality of radio communication systems. 
     As shown in  FIG. 1 , the notebook computer includes a first case  1  and a second case  2 . The first case  1  contains a circuit board on which various electric elements are mounted, a hard disk drive, etc. The second case  2  is provided with a liquid crystal display  4 . The first case  1  and the second case  2  are supported rotatably by hinges  3 . The hinges  3  have a rotation axis for supporting the first and second cases  1 ,  2  rotatably. A keyboard  5  and a pointing device  6  are provided on an upper surface  1   a  of the first case  1 . The keyboard  5  allows a user to input various characters. The pointing device  6  is fixed in the first case  1  with its operating surface being exposed on the surface of the first case  1 . The pointing device  6  allows a user to touch the operating surface and move the cursor displayed on a liquid crystal display  2   a  to a desired position. 
     As shown in  FIG. 2 , the notebook computer of this embodiment includes a communication module  10  that can perform wireless communications. The communication module  10  is contained in the first case  1 . The communication module  10  is located so as to overlap with the pointing device  6  in the thickness direction of the first case  1 . 
     Although  FIG. 2  shows an example of the placement of the communication module  10 , in terms of suppressing an increase in size of the notebook computer and ensuring the transmission and reception characteristics, the communication module  10  is located preferably at the position that overlaps with the pointing device  6 . Since relatively large members such as an electric circuit board (e.g., motherboard), a hard disk drive, and a battery are contained in the first case  1 , and recent notebook computers are increasingly smaller and thinner, it becomes more and more difficult to provide a space for the communication module  10  inside the first case  1 . Furthermore, to ensure good transmission and reception characteristics of the communication module  10 , it is preferable that the communication module  10  is located as close as possible to the side  1   b ,  1   c , or  1   d  of the first case  1 . However, in many cases, a PC card slot and input/output terminals are placed on the sides  1   c ,  1   d . Therefore, a space for the communication module  10  is not likely to be available. Thus, in this embodiment, the communication module  10  is placed in a space under the pointing device  6 , so that the size of the first case  1  is not increased, and the transmission and reception characteristics are ensured because the communication module  10  is close to the side  1   b.    
       FIG. 3A  is a plan view of the communication module  10 .  FIG. 3B  is a cross-sectional view taken along the line Z-Z in  FIG. 3A . The communication module  10  includes a substrate  11 , a first antenna element  12 , a second antenna element  13 , and a ground portion  14 . The first antenna element  12 , the second antenna element  13 , and the ground portion  14  are disposed on a surface  11   a  of the substrate  11 . The first antenna element  12 , the second antenna element  13 , and the ground portion  14  can be formed on the surface  11   a  of the substrate  11 , e.g., by a patterning method. 
     The first antenna element  12  and the second antenna element  13  can transmit and receive radio waves in the same frequency band. Each of the first and second antenna elements  12 ,  13  has a flat transmitting/receiving surface that transmits and receives radio signals. In this embodiment, the first antenna element  12  can transmit and receive radio waves in conformity with the IEEE 802.11 standard (wireless LAN). The second antenna element  13  can transmit and receive radio waves in conformity with the Bluetooth standard. Both the IEEE 802.11 standard and the Bluetooth standard are communication standards using the 2.4 GHz band. Each of the first and second antenna elements  12 ,  13  includes an antenna, a receiving circuit, a transmitting circuit, etc. The first antenna element  12  has an internal pattern  12   a  and a hole  12   b . The second antenna element  13  has an internal pattern  13   a  and a hole  13   b . The internal pattern  12   a  is used to ground electrically the first antenna element  12 . The internal pattern  13   a  is used to electrically ground the second antenna element  13 . The holes  12   b ,  13   b  receive screws  15   a ,  15   b  (as will be described later) for fixing the communication module  10  to the notebook computer and pass through the first antenna element  12 , the second antenna element  13 , and the substrate  11 . The internal patterns  12   a ,  13   a  are formed through the holes  12   b ,  13   b  to the back  11   b  of the substrate  11 . 
     The ground portion  14  is a ground potential. The ground portion  14  has a flat surface and is provided between the first antenna element  12  and the second antenna element  13 . The ground portion  14  includes an internal pattern  14   a , a hole  14   b , and a ground pattern  14   c . The ground pattern  14   c  is disposed on the surface  11   a  of the substrate  11 . The ground pattern  14   c  is formed of a conductor such as a metal, and preferably is formed of a material with excellent conductivity such as copper. The hole  14   b  receives a screw  15   c  (as will be described later) for fixing the communication module  10  to the notebook computer and passes through the ground pattern  14   c  and the substrate  11 . The internal pattern  14   a  is formed on the inner wall of the hole  14   b  and connected electrically to the ground pattern  14   c.    
       FIG. 4A  is a plan view showing the main portion when the communication module  10  is incorporated into the notebook computer shown in  FIG. 1 .  FIG. 4A  illustrates the structure of the first case  1  in the vicinity of the pointing device  6  in the notebook computer, but omits the pointing device  6  for the sake of clarification.  FIG. 4B  is a cross-sectional view taken along the line Z-Z in  FIG. 4A .  FIG. 4B  shows the first case  1 , the pointing device  6 , and the communication module  10  to clarify the positional relationship between them. 
     As shown in  FIGS. 4A and 4B , the communication module  10  is fixed to a frame  17  in the first case  1  by the screws  15   a  to  15   c . The frame  17  is provided with a metal plating layer  16 . Thus, when the communication module  10  is fixed to the frame  17 , the internal pattern  12   a  of the first antenna element  12 , the internal pattern  13   a  of the second antenna element  13 , and the internal pattern  14   a  of the ground portion  14  are in contact with the metal plating layer  16 . In this manner, the first antenna element  12 , the second antenna element  13 , and the ground portion  14  can be grounded. In this embodiment, the metal plating layer  16  is provided because the frame  17  is made of an insulator such as a resin. However, if the frame  17  is made of a conductor such as a metal, the metal plating layer  16  can be removed. Moreover, if the frame  17  is a conductor, and the screws  15   a  to  15   c  are conductors such as metals, the internal patterns  12   a ,  13   a , and  14   a  are not necessarily required. 
     When the communication module  10  shown in  FIGS. 4A and 4B  performs communications based on the wireless LAN standard, first, the first antenna element  12  is actuated. The first antenna element  12  can receive externally propagating radio waves with the receiving circuit via the inner antenna. The first antenna element  12  also can send a transmission signal that is generated by the transmitting circuit to the outside via the antenna. On the other hand, when the communication module  10  performs communications based on the Bluetooth standard, the second antenna element  13  is actuated. The second antenna element  13  can receive externally propagating radio waves with the receiving circuit via the inner antenna. The second antenna element  13  also can send a transmission signal that is generated by the transmitting circuit to the outside via the antenna. 
     In this case, since the first antenna element  12  and the second antenna element  13  are designed to transmit and receive radio waves in the same frequency band, the radio waves may leak from the first antenna element  12  to the second antenna element  13  or from the second antenna element  13  to the first antenna element  12 . This embodiment provides the ground portion  14  between the first antenna element  12  and the second antenna element  13 , and therefore can release the unwanted radio waves leaking from one of the first and second antenna elements  12 ,  13  to the other via the ground portion  14  and the metal plating layer  16 . Thus, the degradation of the isolation between the first antenna element  12  and the second antenna element  13  can be suppressed. 
     In this embodiment, the ground portion  14  is provided between the first antenna element  12  and the second antenna element  13  of the communication module  10 , thereby suppressing the degradation of the isolation between the first antenna element  12  and the second antenna element  13 . Accordingly, the degradation of the transmission and reception characteristics of the communication module  10  can be suppressed. 
     The arrangement of the ground portion  14  between a plurality of antenna elements that transmit and receive radio waves in the same frequency band further can increase the effect of improving the isolation. If a plurality of antenna elements using radio waves in the same frequency band are located close to each other, the isolation between the antenna elements is likely to be degraded. However, such degradation of the isolation can be suppressed by providing the ground portion  14  between the first antenna element  12  and the second antenna element  13 , as described in this embodiment. 
     The first antenna element  12 , the second antenna element  13 , and the ground portion  14  are placed together on the same substrate  11 , and thus can share the wiring in the substrate, resulting in a small communication module. Moreover, the communication apparatus including this communication module can be made smaller. If the first antenna element  12 , the second antenna element  13 , and the ground portion  14  are mounted on separate substrates, man-hours are required to fix each of the substrates to the communication apparatus. However, the man-hours for fixing the individual substrates to the communication apparatus can be reduced by mounting the first antenna element  12 , the second antenna element  13 , and the ground portion  14  together on a single substrate. 
     In the ground portion  14  of this embodiment, although the ground pattern  14   c  is disposed on the surface  11   a  of the substrate  11  as shown in  FIG. 3B , another ground pattern may be disposed on the back  11   b  of the substrate  11 . Moreover, a ground pattern may be disposed inside the substrate  11 .  FIG. 5A  is a plan view showing a modified example of the communication module of this embodiment.  FIG. 5B  is a cross-sectional view taken along the line Z-Z in  FIG. 5A . As shown in  FIGS. 5A  and  5 B, a ground portion  24  includes a first pattern  24   a  disposed on the surface  11   a  of the substrate  11 , a second pattern  24   b  disposed inside the substrate  11 , and a third pattern  24   c  disposed on the back  11   b  of the substrate  11 . The first pattern  24   a , the second pattern  24   b , and the third pattern  24   c  are arranged in layers in the thickness direction of the substrate  11 . This configuration further can suppress the degradation of the isolation between the first antenna element  12  and the second antenna element  13 . When the ground pattern (i.e., the second ground pattern  24   b ) further is disposed inside the substrate  11 , no space is needed to dispose a ground pattern on the surface  11   a  and the back  11   b  of the substrate  11 . Thus, the effect of suppressing the degradation of the isolation can be increased without increasing the size of the communication module  10 . The ground pattern disposed inside the substrate  11  is not limited to a single layer as shown in  FIG. 5B , and may be formed as a plurality of layers. 
     Another module may be provided on the ground portion  14 .  FIG. 6A  is a plan view showing a modified example of the notebook computer of this embodiment and illustrates the main portion in the vicinity of the pointing device  6 .  FIG. 6B  is a cross-sectional view taken along the line Z-Z in  FIG. 6A . As shown in  FIG. 6A , the notebook computer in this modified example has a fingerprint sensor  7  near the pointing device  6 . The fingerprint sensor  7  detects the contact of a finger of the user&#39;s hand. The notebook computer compares the fingerprint of the user read by the fingerprint sensor  7  with previously registered fingerprints. If there is a match, then the user is allowed to operate the notebook computer. If there is no match, then the user is not allowed to operate the notebook computer. The fingerprint sensor  7  is bonded on the ground portion  14 , as shown in  FIG. 6B . In this case, a ground terminal (not shown) of the fingerprint sensor  7  is connected electrically to the ground portion  14 , which eliminates the need for wiring or the like that connects the ground terminal (not shown) of the fingerprint sensor  7  to the ground pattern in the notebook computer. Thus, cost reduction and space saving can be achieved. 
     In the configuration of  FIGS. 6A and 6B , although the fingerprint sensor  7  is provided on the ground portion  14 , other elements also may be provided. Needless to say, it is preferable that the element provided on the ground portion  14  does not have an adverse effect on the isolation between the first antenna element  12  and the second antenna element  13 . 
     The communication standard for each of the first and second antenna elements  12 ,  13  is an example. The first antenna element  12  and the second antenna element  13  may be adaptable to at least the communication standards using the same frequency band. 
     The communication module of this embodiment includes two antenna elements, but may include three or more antenna elements. In such a case, ground patterns may be provided between each of the antenna elements, so that the effect similar to that of this embodiment can be obtained. 
     The communication module of this embodiment may be applied not only to the equipment (a notebook computer, a game machine, etc.) that usually can be used alone, but also to, e.g., the peripheral equipment. For example, the communication module may be applied to a network device that can be connected externally to a notebook computer. The network device may be, e.g., a network card that includes a connector having a shape in conformity with the PCMCIA (personal computer memory card international association) standard or a network device that can be connected to an external connection terminal such as a USB (universal serial bus) terminal provided in a notebook computer. The above peripheral equipment is included in the scope of the communication apparatus of the present invention. 
     The first antenna element  12  and the second antenna element  13  of this embodiment are examples of the antenna elements of the present invention. The ground portions  14 ,  24  of this embodiment are examples of the isolation member of the present invention. 
     The invention may be embodied in other forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed in this application are to be considered in all respects as illustrative and not limiting. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are intended to be embraced therein.