Abstract:
An electronic apparatus according to the present invention includes two modules which decode high frequency analog signals. Furthermore, each of the modules is provided with an RF section at a position away from the center of the module in either longitudinal direction to carry out radio communications using high frequencies. In this electronic apparatus, the two modules are arranged so that their longitudinal sides extend parallel with each other in opposite directions. The two modules are also misaligned with each other in the longitudinal direction so that the RF sections lie away from each other and so that connectors to which signals subject to noise interference are inputted lie away from each other.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based upon and claims the benefit of priority from the prior Japanese Patent Application No. 2002-378281, filed Dec. 26, 2002, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a mutual interference preventing technique used if a plurality of modules handling high frequency signals are installed. 
     2. Description of the Related Art 
     In recent years, electronic apparatus called a home server or the like has started to be popularized which has both a TV viewing function and an Internet browsing function (refer to, for example, Jpn. Pat. Appln. KOKAI Publication No. 2001-358966). Electronic apparatus of this kind is installed in, for example, a living room and connected to personal computers in different rooms via a LAN. Then, on the basis of not only direct operations in the living room using a remote controller or operation buttons but also requests transmitted by the personal computers in the different rooms via the LAN, this electronic apparatus receives and transfers TV broadcast program data via the LAN or acquires and transfers home page data publicized on the Internet, via the LAN. 
     That is, a user can carry out TV viewing or Internet browsing in his or her own room without the need to provide his or her personal computer with the TV viewing function and the Internet browsing function. 
     Furthermore, with recent improved image processing techniques or the like, information processing on a computer makes it possible to, for example, view a TV program broadcast on a channel A, while recording a different TV program broadcast on a channel B in the same time slot. Thus, it has been increasingly necessary to also mount a plurality of TV tuners in electronic apparatus of this kind. 
     For example, a television apparatus with a recording function contains a plurality of TV tuners. In general, these TV tuners are mounted at certain distances from one another so as not to interfere with one another. However, in the previously described electronic apparatus such as a home server, the area in which a printed circuit board is mounted is significantly limited. Accordingly, it is impossible to employ a mounting method such as the one used for television apparatuses with a recording function. Therefore, a certain improvement is required for this electronic apparatus. For example, Jpn. Pat. Appln. KOKAI Publication No. 2002-073210 and Jpn. Pat. Appln. KOKAI Publication No. 09-097993 disclose improvements made to allow the arrangement of a plurality of radio communication modules in a limited mounting area. 
     However, in Jpn. Pat. Appln. KOKAI Publication No. 2002-073210, two radio communication modules mounted in portable information apparatus are based on different radio communication methods. With the different radio communication methods, the level of the mutual interference between the radio communication modules is much lower than that in the case with the same radio communication method. That is, it is inappropriate to apply this mounting method, which does not take mutual interference into account, to apparatus using the same radio communication method. 
     Furthermore, in Jpn. Pat. Appln. KOKAI Publication No. 09-097993, two radio communication modules are mounted in a high frequency apparatus by laying one substrate on top of another. It is thus difficult to apply this method to recent electronic apparatus that tends to be thinner. 
     BRIEF SUMMARY OF THE INVENTION 
     According to an embodiment of the present invention, an electronic apparatus comprises a circuit board, a splitter mounted on the circuit board, and receiving a signal, a first module mounted on the circuit board, and having a first connecting portion electrically connected to the splitter, and a second module mounted on the circuit board, and having a second connecting portion electrically connected to the splitter, the second connecting portion located in an opposite direction to the first connecting portion. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
       The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate presently preferred embodiments of the invention, and together with the general description given above and the detailed description of the embodiments given below, serve to explain the principles of the invention. 
         FIG. 1  is a view showing the configuration of a home network system using electronic apparatus (a wireless AV (Audio and Video) station) according to an embodiment of the present invention; 
         FIG. 2  is a diagram showing the configuration of apparatus in the wireless AV station according to this embodiment; 
         FIG. 3  is a view showing the wireless AV station according to this embodiment as viewed from its rear; 
         FIG. 4  is a view showing an example in which the components of the wireless AV station according to this embodiment are arranged on the same substrate; and 
         FIGS. 5A and 5B  are views illustrating the principle of realization of the limitation of the mutual interference between two tuners to within an allowable range, in the wireless AV station according to this embodiment. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     An embodiment of the present will be described below with reference to the drawings. 
       FIG. 1  shows the configuration of a home network system using electronic apparatus (a wireless AV (Audio and Video) station) according to an embodiment of the present invention. 
     This home network system is composed of, for example, a wireless AV station  101 , TV receiver  102 , and various information processing terminals such as notebook type personal computers  103  and  104  and a desktop type personal computer  105 . The wireless AV station  101  is a radio transmission apparatus functioning as a home network server apparatus. The wireless AV station  101  wirelessly provides the domestic information processing terminals such as the personal computers  103  to  105  with services for the viewing of TV broadcast program data, Internet browsing, and the like. 
     The wireless AV station  101  is connected to an external global network (external network) such as the Internet  12  via a communication line  13  such as the ISDN, ADSL, or CATV. Moreover, the wireless AV station  101  is connected to the various domestic information processing terminals via a wired or wireless network constituting a home network. The notebook type personal computers  103  and  104  are each provided with a radio communication device and wirelessly connected to the wireless AV station  101 . Furthermore, the desktop type personal computer  105  is connected to the wireless AV station  101  via a wired LAN. 
     The wireless AV station  101  connects each of the personal computers  103  to  105  to the Internet  12  to transmit data between each of the personal computers  103  to  105  and WEB sites on the Internet  12 . 
     An antenna cable connected to a TV broadcast reception antenna  11  installed outdoors is drawn into the house and connected to the TV receiver  102  and the wireless AV station  101 . TV broadcast program data can be reproduced by the TV receiver  102  or can be received by the wireless AV station  101 . The wireless AV station  101  can wirelessly transmit received TV broadcast program data to the notebook type personal computers  103  and  104  via the wireless LAN. The wireless AV station  101  can also transmit data to the desktop type personal computer  105  via the wired LAN. 
     Description will be given below of main functions provided by the wireless AV station  101 . 
     Wireless Router Function: 
     This is a function of wirelessly connecting any of the information processing terminals that can communicate via the wireless LAN, to the Internet  12  to transmit data between the information processing terminal and WEB sites on the Internet  12 . Internet browsing can be carried out from anywhere in the house by using the notebook type personal computer  103  or  104  connected to the wireless AV station  101  via the wireless LAN. 
     TV Function: 
     This is a function of transmitting TV broadcast program data received by the wireless AV station  101 , to any of the information processing terminals connected to the wireless AV station  101  via the wireless or wired LAN. A TV broadcast program on the air can be wirelessly viewed from anywhere in the house by using the notebook type personal computer  103  or  104 . 
     TV Recording Function: 
     The wireless AV station  101  contains a magnetic disk drive device (hard disk drive; HDD). Accordingly, while wirelessly viewing a TV broadcast program, a user can record this program in the magnetic disk drive device. Furthermore, while transmitting TV broadcast program data recorded in the magnetic disk drive device to one of the information processing terminals, the user can receive another TV broadcast program on the air and record it in the magnetic disk drive device. Moreover, the user can output TV broadcast program data recorded in the magnetic disk drive device, to the TV receiver  102  to view it on a large screen. 
     Remote Control Function: 
     Each of the personal computers  103  to  105  can wirelessly control the TV function, TV recording function, and other functions of the wireless AV station  101 . Furthermore, the TV function, TV recording function, and other functions of the wireless AV station  101  can be controlled using an exclusive remote control unit used to operate the wireless AV station  101 . 
     Furthermore, the wireless AV station  101  can simultaneously execute the TV function and the TV recording function. Specifically, it is possible to, for example, view a TV program broadcast on a channel A, while recording another TV program broadcast on a channel B. That is, the wireless AV station  101  is what is called double tuner type electronic apparatus. 
       FIG. 2  is a diagram showing the configuration of apparatus in the wireless AV station  101 . 
     As shown in  FIG. 2 , the wireless AV station  101  is mainly composed of four components including two MPEG modules  21 , a CPU module  31 , and a communication module  41 . The two MPEG modules  21 , the CPU module  31 , and the communication module  41  are connected to a bus  20  such as a PCI bus. 
     Each of the MPEG modules  21  executes a process of receiving TV broadcast program data, an encoding process of compression-encoding the received TV broadcast program data, a decoding process of decoding the compression-encoded TV broadcast program data, and other processes. As shown in  FIG. 2 , each MPEG module  21  is provided with a TV tuner  211 , an NTSC decoder  212 , a sound multiplex decoder  215 , an audio A/D converter (audio ADC)  214 , an MPEG encoder  215 , a RAM  216 , a PCI bus interface (PCI-IF)  217 , an MPEG2 decoder  218 , a RAM  219 , an audio D/A converter (audio DAC)  220 , and other components. 
     The TV tuner  211  is connected to a TV antenna cable via a TV antenna connector  301  and a splitter  306 . The splitter  306  distributes a TV signal inputted from the TV broadcast reception antenna  11  via the TV antenna connector  301 , to each of the two TV tuners  211 . The TV tuner  211  receives TV broadcast program data transmitted on a channel requested by one of the personal computers  103  to  105  or the remote control unit. The TV tuner  211  receives TV broadcast signals and selects a channel on the basis of the viewing request. A video signal for TV broadcast program data transmitted on a certain channel is received by the TV tuner  211  and then transmitted to the NTSC decoder  212 . The NTSC decoder  212  then converts the video signal into digital data. An audio signal is transmitted from the sound multiplex decoder  213  to the audio ADC  214 . The audio ADC  214  then converts the audio signal into a digital signal. 
     The NTSC decoder  212  is also connected to a video input terminal  302  and can thus receive video signals inputted by external video apparatus such as a DVD player or a VCR. A sound multiplex signal superimposed on TV broadcast program data is decoded by the sound multiplex decoder  213  and then transmitted to the audio A/D converter (audio ADC)  214 . The audio A/D converter  214  then converts the sound multiplex signal into digital data. The audio A/D converter (audio ADC)  214  is also connected to the audio output terminal  304  and can thus receive audio signals inputted by external video and audio apparatus. 
     The MPEG2 encoder  215  compression-encodes each of inputted video and audio data. MPEG2 is used for this compression-encoding. The RAM  216  is used by the MPEG2 encoder  215  as a work memory to execute a compression-encoding process. TV broadcast program data received by the TV tuner  211  is compression-encoded by the MPEG2 encoder  215  and converted into an MPEG2 stream. 
     The PCI bus interface (PCI-IF)  217  connects the MPEG module  21  to the bus  20  and is used to communicate with each of the CPU module  31  and HDD  51  via the bus  20 . The PCI bus interface (PCI-IF) contains a group of registers that can be accessed by the CPU module  31 . Operations of the TV tuner  211  and MPEG2 encoder  215  are controlled in accordance with commands set in the group of registers by the CPU module  31 . 
     The MPEG2 decoder  218  decodes TV broadcast program data compression-encoded into an MPEG2 format. For example, if compression-encoded TV broadcast program data recorded in the HDD  51  is to be viewed using the TV receiver  102 , the compression-encoded TV broadcast program data read from the HDD  51  is transmitted to the MPEG2 decoder  218  via the PCI bus interface  217 . The MPEG2 decoder  218  then decodes (expands) the TV broadcast program data. The RAM  219  is used by the MPEG2 decoder  218  as a work memory to execute a decoding process. Operations of the MPEG2 decoder  218  are also controlled in accordance with commands set in the group of registers by the CPU module  31 . 
     Video data decoded by the MPEG2 decoder  218  is transmitted to, for example, the TV receiver  102  via graphics  221  and then a video output terminal  305 . Audio data decoded by the MPEG2 decoder  218  is converted into an analog signal by the audio D/A converter (audio DAC)  220  as required. The converted signal is then outputted from an audio output terminal  304  to external audio/video apparatus. 
     Moreover, according to the present embodiment, TV broadcast program data decoded by the MPEG2 decoder  218  can be transmitted to the MPEG2 encoder  215 . The MPEG2 encoder  215  can then execute a compression-encoding process again. This operation is used for a down convert process of converting a transmission rate (bit rate) for compression-encoded TV broadcast program data recorded in the HDD  51  into a particular transmission rate for radio transmissions. 
     Specifically, the transmission rate (bit rate) for TV broadcast program data obtained by a compression-encoding process executed by the MPEG2 encoder  215  varies depending on the quality of images (low, standard, and high image quality) in TV broadcast program data to be recorded in the HDD  51 . If the high quality is selected, TV broadcast program data compression-encoded at a very high transmission rate is recorded in the HDD  51 . In this case, in a radio communication band, the TV broadcast program data may not be transmitted in real time. Then, a down convert process is automatically executed to reduce the transmission rate for the TV broadcast program data to be wirelessly transmitted, to a particular one for radio transmissions. 
     The CPU module  31  controls the TV tuner  211 , MPEG2 encoder  215 , and MPEG2 decoder  218  of the MPEG module  21 . The CPU module  31  also controls data writes to the HDD  51  and data reads from the HDD  51 . Furthermore, through communications with the communication module  41 , the CPU module  31  receives a command for TV viewing transmitted by one of the personal computers  103  to  105  and transmits TV broadcast program data to be sent to one of the personal computers  103  to  105 , to the communication module  41 . The CPU module  31  is composed of a CPU  311 , a north bridge  312  connecting a CPU bus for the CPU  311  and the PCI bus  20  together, and a main memory  313 . 
     The communication module  41  is a communication control device that can operate independently as a LAN router. The communication module  41  is configured to connect wirelessly to the personal computers  103  and  104  and is also connected to the personal computer  105  via the wired LAN. In response to a request transmitted by one of the personal computers  103  to  105 , the communication module  41  connects this personal computer  103  to  105  to the Internet  12  to transmit data between the personal computer  103  to  105  and the Internet  12 . In this case, the processes for the transmission of data between the personal computer  103  to  105  and the Internet  12  are all executed within the communication module  41 , whereas the CPU module  31  is not used. 
     The communication module  41  is provided with a control processor  411 , a RAM  412 , a ROM  413 , a network controller  414 , a wireless LAN device  415 , a WAN connector  501 , a LAN connector  502 , and the like. 
     The WAN connector  501  is a broadband terminal used to transmit and receive data to and from the Internet  12 , and is connected to the communication line  13  via, for example, a modem. The LAN connector is connected to the domestic wired LAN. 
     The network controller  414  is a network control device that controls the transmission of data between the communication module  41  and the Internet  12  via the WAN connector  501  and the transmission of data between the communication module  41  and the domestic wired LAN via the LAN connector  502 . The wireless LAN device  415  is a radio communication device that transmits and receives data to and from the personal computers  103  and  104 . The wireless LAN device  415  communicates wirelessly with the personal computers  103  and  104  via the antenna  416 . The wireless LAN device  415  conforms to a standard such as IEEE802.11b or IEEE802.11a. 
     The control processor  411  controls the network controller  414  and the wireless LAN device  415  and thus the transmission of data between the personal computers  103  to  105  and the Internet  12 . Specifically, the control processor  411  includes an IP masquerade function, a NAT function, and a DHCP function which are required to allow the communication module  41  to operate as a wireless router. Moreover, the control processor  411  is connected to the PCI bus  20 . The control processor  411  has a function of notifying, via the PCI bus  20 , the CPU  311  of a request (command) for TV viewing which request is received from the personal computer  103  or  104  via the wireless LAN device  415 . The control processor  411  can also notify, via the PCI bus  20 , the CPU  311  of a request (command) for TV viewing received from the personal computer  105  on the wired LAN via the network controller  414 . 
     Moreover, the control processor  411  has a function operating if it receives TV broadcast program data transferred by the CPU  311  via the PCI bus  20 , to transmit the TV broadcast program data to the requesting personal computer via the wireless LAN device  415  or the network controller  414 . In this case, the process of transmitting the TV broadcast program data to the requesting personal computer is executed concurrently with the transmission of data between this personal computer and the Internet  12 . 
     For example, it is assumed that while the personal computer  103 , which can be wirelessly connected to the communication module  41 , is carrying out Internet browsing, TV program data requested by the personal computer  103  is wirelessly transmitted to the personal computer  103 . Then, the control processor  411  controls the wireless LAN device  415  so as to transmit wirelessly contents data received from a WEB server on the Internet  12  and TV broadcast program data compression-encoded by the MPEG module  21 , to the personal computer  103  in a time division manner. Specifically, the control processor  411  multiplexes the contents data and the compression-encoded TV broadcast program data and wirelessly transmits the multiplexed contents data and TV broadcast program data to the personal computer  103  in a time division manner. By thus independently transmitting contents data and TV broadcast program data to the personal computer  103 , the personal computer  103  can simultaneously display the contents data and the TV broadcast program data using corresponding application programs. Furthermore, the corresponding application programs can be used to vary freely the displayed positions and sizes of windows for the contents data and TV broadcast program data. 
     The above functions of the control processor  411  are realized by firmware stored in the ROM  413 . 
       FIG. 3  shows the appearance of the wireless AV station  101  as viewed from its rear. 
     As shown in  FIG. 3 , the wireless AV station  101  has a vertically installed housing called a tower type or the like. The rear surface of the wireless Av station  101  is provided with a radiating fan and a connector for a network connection, as well as the splitter  306 , used to connect each of the TV tuners  211  of the two MPEG module  21 , shown in  FIG. 2 , to the TV antenna cable. 
     Since the vertically installed wireless AV station  101  is installed next to, for example, the TV receiver  102 , it is preferably made as thin as possible. Furthermore, to make the area on the substrate well-organized, the two TV tuners  211  must be provided adjacent to an end of the substrate which is closer to the TV antenna connector  301 . 
     On the other hand, the TV tuners  211  of the two MPEG modules  21  each comprise a radio communication function based on the same radio communication method. Accordingly, if the TV tuners  211  are provided adjacent to each other on the same substrate, they are likely to interfere with each other. Thus, the wireless AV station  101  according to this embodiment is characterized in that the two TV tuners  211 , i.e. the radio communication modules can be arranged within a limited mounting area while limiting mutual interference to within an allowable range. This point will be described below. 
       FIG. 4  is a view showing an example in which the components of the wireless AV station  101  are arranged on the same substrate. 
     As shown in  FIG. 4 , the CPU module  31 , the core of the wireless AV station  101 , is provided on the substrate installed in the wireless AV station  101 . Furthermore, on the substrate, the two tuners  211 , i.e. the radio communication modules each comprising the radio communication function based on the same radio communication method, are provided adjacent to each other within a limited mounting area X at the end of the substrate which is closer to the splitter  306 . 
     A connector  211 A is provided at one end of each tuner  211  to connect to the splitter  306  via a cable. That is, in the prior art, the two tuners  211  are commonly arranged adjacent to and parallel with each other in the same direction so that the connectors  211   a  lies opposite the corresponding TV antenna connectors  301 . In contrast, in the wireless AV station  101 , the connectors  211 A are arranged so as to extend in the opposite directions, i.e. one of the connectors  211 A is located away from the TV antenna connectors  301  so that the two tuners  211  lie adjacent to and parallel with each other and opposite each other in a longitudinal direction. At the same time, in the wireless AV station  101 , the two tuners  211 , which are configured with a rectangular parallelepiped shape, are arranged so as to be intentionally misaligned with each other by a distance n in the direction in which the connectors  211 A extend. 
     Moreover, in the present embodiment, the tuner  211  mounted closer to the splitter  306  is arranged so that its connector  211 A sits further from the splitters  306 . On the other hand, the other tuner  211  is arranged so that its connector  211 A sits closer to the splitters  306 . This is because the tuner  211  mounted closer to the splitters  306  cannot be connected to the corresponding splitter  306  easily during manufacturing when its connector  211 A is located too close to the splitters  306 . If a predetermined distance can be set between the splitters  306  and the tuners  211 , the tuner  211  mounted closer to the splitters  306  may be arranged so that its connector  211 A lies closer to the splitters  306 , while the other tuner  211  may be arranged so that its connector  211 A lies further from the splitters  306 . 
     This arrangement is employed in order to limit, to within an allowable range, the mutual interference between the radio communication modules each comprising the radio communication function based on the same radio communication method, i.e. the radio communication modules that are likely to interfere with each other, if they must be provided adjacent to each other within the limited mounting area X. Now, with reference to  FIGS. 5A and 5B , description will be given of the principle of realization of the limitation of the mutual interference between two tuners  211  to within an allowable range, based on the above arrangement. 
     In the wireless AV station  101 , an RF module  211 B of each tuner  211  is provided between the center of the tuner  211  and the corresponding connector  211 A as shown in  FIGS. 5A and 5B . Accordingly, by arranging one of the tuners  211  as shown in  FIG. 5A  while arranging the other as shown in  FIG. 5B , a distance is set between the RF modules  211 B, contained in the respective tuners  211 , the distance being required to reduce the mutual interference between the tuners  211 . Furthermore, a larger distance can be set by arranging the two tuners  211  so that they are misaligned with each other in the direction in which the connectors  211 A extend. 
     Specifically, in the wireless AV station  101 , the appropriate distance is set between the TV tuners  211  by providing the RF module  211 B of each TV tuner  211  between the center of the TV tuner  211  and the connector  211 A and arranging the the two tuners  211  on each of the MPEG modules  21  so that the connectors  211 A lie adjacent to and parallel with each other so as to extend in the opposite directions and so that the tuners  211  are misaligned with each other in the direction in which the connectors  211 A extend. 
     Thus, the two tuners  211  can be arranged within the limited mounting area while limiting the mutual interference between the two tuners  211  to within an allowable range. This makes it possible to minimize the area of the substrate which is sandwiched between the two tuners  211  and which is thus not worth utilizing and to make the remaining area on the substrate well-organized to increase the utilization of the area. It is thus possible to make the wireless AV station  101  thinner and smaller. 
     The TV tuner  211  has been described above as an example of the radio communication module. The method according to the present invention is not limited to the TV tuner but is applicable to any radio communication modules handling analog signals and comprising radio communication functions based on the same radio communication method. 
     Furthermore, in the examples described above, the TV tuners  211  are arranged so that the connectors  211 A lie adjacent to and parallel with each other so as to extend in the opposite directions and so that the TV tuners  211  are misaligned with each other in the direction in which the connectors  211 A extend. However, depending on the position of the RF module  211 B in the TV tuner  211 , it may be unnecessary to misalign the TV tuners  211  with each other in the direction in which the connectors  211 A extend. 
     Moreover, if for example, the RF module  211 B is provided between the center of the TV tuner  211  and its end opposite to the connector  211 A, similar effects are produced by misaligning the TV tuners  211  with each other in the direction opposite to the one in which the connectors  211 A extend. 
     Additional advantages and modifications will readily occur to those skilled in the art. Therefore, the invention in its broader aspects is not limited to the specific details and representative embodiments shown and described herein. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.