JP2004343725A - Wireless communication apparatus, wireless av system, operation control program, and recording medium recording program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the usability of a user by not causing an unnatural feeling to the user even if the video displaying is interrupted due to a change-over of transmission channels or the like. <P>SOLUTION: A wireless A/V system 1 comprises a wireless center 2, which serves as a base device, and a TV body 3. The TV body 3 includes: an SS transmitter/receiver unit 61 that receives MPEG2 streams and command transmission data transmitted from an SS transmitter/receiver unit 61 of the wireless center 2 and that decodes the received MPEG2 streams and others; a TV part 63 that displays video signals and outputs audio signals; a TV microcomputer 64 that controls the whole apparatus; and a second SS-CPU 84 that determines the status of communication between the wireless center 2 and the TV body 3 from the field intensity of a received radio wave and from a re-transmission request based on an error ratio. The TV microcomputer 64 OSD-displays, on the basis of the determined communication status, on the TV part 63, messages of reception sensitivity information including such indications that the video and audio data have been interrupted, the transmission channels are being changed, the connection is being made and that the communication is impossible due to a blind spot. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a wireless communication device, a wireless AV system, an operation control program, and a recording medium storing the program.

  2. Description of the Related Art In recent years, with the explosive spread of the Internet, cases where a LAN (Local Area Network) is constructed in offices, homes, and the like have been increasing. With the advance of digital wireless communication technology, the need for so-called wireless LAN, which constructs a wireless LAN, has been greatly increased due to the cumbersome cable wiring, and the mobile environment for mobile terminals typified by notebook computers. Underneath is that it can also be used, and a considerable number of popular vehicles are expected in the future. As a typical technology of the wireless LAN, there is already IEEE 802.11 standardized in IEEE (Institute of Electrical and Electronics Engineers). This standardized technology defines a layer from a physical layer to a MAC (Media Access Control) layer which is a lower layer of a data link in an OSI model, and is a wired LAN transmission path, Ethernet. (Registered trademark), and the specification is such that a roaming function can be provided as an additional function because it is wireless.

  In addition, preparations for a new terrestrial digital broadcast that will replace the analog terrestrial broadcast currently being viewed nationwide are in progress. This digital terrestrial broadcasting was started in the three major metropolitan areas of Kanto, Kinki and Tokai in 2003, and is planned to be expanded nationwide in 2006. Accordingly, the current analog broadcasting will be abolished in 2011.

  ISDB (Integrated Services Digital Broadcasting) is a concept of next-generation integrated digital broadcasting that handles all information such as video, audio, and data as digital data. As specific services of ISDB, digital television broadcasting, digital audio broadcasting, facsimile broadcasting, multimedia broadcasting, and the like have been studied. As an ISDB transmission line, use of a satellite broadcast wave, a terrestrial broadcast wave, or a wired transmission line of a coaxial cable or an optical fiber is considered.

  This terrestrial digital broadcasting technical standard ISDB-T (Terrestrial) adopts OFDM (Orthogonal Frequency Division Multiplexing) which uses a large number of carriers for the modulation method, and uses multiple propagation paths (multipath) such as reflection from a building. Ghost disturbance can also be suppressed. Further, ISDB-T defines a plurality of transmission modes for defining carrier intervals, a modulation method for each carrier, and a plurality of guard intervals in the time axis direction provided for each effective symbol length. Is acceptable. In practice, an optimum format is selected from these services according to services such as fixed reception and mobile reception.

  In ISDB-T, one transmission channel (communication channel) (band of about 5.6 MHz) is divided into 13 segments (1 segment = about 430 kHz), and the modulation method is changed in units of this. As a result, the broadcasting station can arbitrarily determine the signal configuration such as audio broadcasting and high-vision broadcasting, standard fixed broadcasting and mobile broadcasting on one transmission channel.

  Furthermore, ISDB-T incorporates interleaving in the time axis direction, and the radio waves used are also suitable for transmission to mobile objects. Therefore, mobile receivers such as in-vehicle televisions, PDAs (Personal Digital Assistants), and mobile phones One of the great features is that stable reception is possible even with a portable terminal such as the one described above. In the future, services that assume such mobile reception are also expected to be highly expected.

  By the way, in a wireless network, when a transmitter and a receiver are communicating at a specific frequency (transmission channel), when the same transmission channel is used by another pair of a transmitter and a receiver, the data transmission band is Because of the decrease, devices that use the transmission channel later need to automatically change to a vacant transmission channel.

As a wireless communication device for changing a transmission channel, for example, in Patent Document 1, a wireless communication unit is provided with a 2.4 GHz band front end circuit and a 5 GHz band front end circuit to provide two 2.4 GHz band and 5 GHz band. By adapting to the frequency band, the number of transmission channels that can be set simultaneously in the same area in the wireless LAN system is greatly increased, and the possibility that the communication link is interrupted by the interference wave is reduced.
JP-A-2002-33676 (publication date: January 31, 2002) (FIG. 1)

  However, in such a conventional wireless communication device, when switching the transmission channel, the communication state is interrupted, so that the video is not displayed, and the user has changed the transmission channel because the video was interrupted. There was a problem of not knowing.

  The present invention has been made in order to solve the above-described problems, and improves the usability of a user by preventing the user from feeling uncomfortable even when the display of video is interrupted due to a change in transmission channel or the like. It is an object of the present invention to provide a wireless communication device, a wireless AV system, an operation control program, and a recording medium on which the program can be recorded.

  Another object of the present invention is to provide a wireless communication device, a wireless AV system, an operation control program, and a recording medium on which the program is recorded, which can maintain an optimal communication state as possible over the entire network.

  In order to solve the above problem, a wireless communication apparatus according to the present invention includes: a communication unit that transmits and receives a control command including video and audio data or communication channel change information; a communication state detection unit that detects a communication state; And a notifying unit for notifying at least the transmission state of the video and audio data based on the communication state detected by the state detecting unit.

  Further, the communication channel may be measured by measuring the time when the communication is interrupted and until a predetermined time elapses after the communication is interrupted.

  The communication means may transmit the video and audio data or the control command by an SS (Spread Spectrum) wireless system.

  The communication means may transmit the video and audio data by an MPEG stream conforming to the MPEG2 encoding method.

  The communication means may be low-power short-range two-way wireless communication.

  Further, as a more preferable specific mode, the communication means is Bluetooth, UWB, or wireless LAN.

  More preferably, the communication state detecting means detects the communication state based on the electric field strength of the received radio wave, the error rate, or the number of retransmission requests based on the error rate.

  More preferably, the communication state detecting means detects a communication state between wireless communication devices with which a communication link has been established.

  Further, the notifying unit notifies at least one of at least one of the video and audio data being interrupted, the communication channel being changed, the connection being established, and the reception sensitivity information including out of communication range. May be used.

  The notification means may be a message display by a display means or a message sounding by a voice output means.

  A wireless AV system according to the present invention is a wireless AV system that connects a plurality of wireless communication devices via a wireless network, wherein the wireless communication device is the wireless communication device according to any one of claims 1 to 10. It is characterized by:

  As a more preferable specific mode, the wireless communication device is a television receiver including a display device, a center device having a broadcast receiving tuner, and transmitting video and audio data to the display device. .

  Also, the present invention provides a method for transmitting and receiving a control command including video and audio data or communication channel change information in a plurality of wireless communication devices constituting a wireless network, detecting a communication state, and detecting a communication state based on the detected communication state. A program for causing a computer to execute at least a control process for notifying the transmission status of the video and audio data.

  Further, the present invention provides, in a plurality of wireless communication devices constituting a wireless network, transmitting and receiving a control command including video and audio data or communication channel change information, detecting a communication state, and based on the detected communication state. A computer-readable recording medium having recorded thereon a program for causing a computer to execute at least a control process for notifying a transmission state of the video and audio data.

  As described above, according to the present invention, it is possible to prevent the user from feeling uncomfortable even when the display of video is interrupted due to a change in communication channel or the like, and to improve the usability of the user.

  Further, it is possible to prevent frequent switching of channels and maintain an optimal communication state as possible over the entire network.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a block diagram showing a configuration of a wireless AV system 1 according to an embodiment of the present invention. This is an example in which the wireless AV system 1 according to the present embodiment is applied to a display-separated wireless TV receiver. FIG. 10 is an explanatory diagram schematically showing a wireless AV system 1 which is a display-separated type wireless TV receiver.

  As shown in FIGS. 1 and 10, a wireless AV system 1 includes a wireless center unit (hereinafter, referred to as a wireless center) 2 as a base device and a television (TV) main unit (hereinafter, a portable terminal (wireless terminal)). , TV main unit) 3, and the wireless center 2 (wireless communication device, center device) and the TV main unit 3 (wireless communication device, display device) form a pair to form a wireless transmission network.

  As shown in FIG. 10, the TV main body 3 is wireless with a built-in battery. In addition, a remote controller is provided so that a remote controller of a video deck or the like can be operated. The wireless center 2 is connected to antennas such as BS and U / V, and AV devices such as DVD players and VCRs. Then, video and / or audio data is wirelessly transmitted from the wireless center 2 to the TV main body 3.

  As shown in FIG. 1, the wireless center 2 includes a video 1 input terminal (S terminal) for connecting each of the antenna terminals such as a BS terminal 11, a U / VHF antenna terminal 12, and a diversity terminal 13 to devices such as a digital VTR and a DVD player. , A video 2 input terminal (decoder input) 15, a video 3 input terminal (monitor / BS output) 16, an AC power supply 17, and a Car-DC power supply 18.

  The TV main body 3 includes a video 4 input terminal (also used for TV output) 21 for connecting devices such as a digital VTR and a DVD (Digital Versatile Disc) player, an AC power supply unit 22, and a Car-DC power supply unit 23.

  The TV main body 3 is a thin display device that is separable from the wireless center 2 and is portable or portable with a built-in battery. , And is not limited by the display mechanism. Further, in this specification, the TV main body 3 mainly has a display function, an audio function, and the like, while the wireless center 2 mainly accommodates a control function for controlling the tuner section, the TV main body 3, and the like. The TV main body 3 according to the present embodiment will be described using a liquid crystal television as an example of a thin display device.

  Data (video and / or audio data) is transmitted and received between the wireless center 2 and the TV main body 3 by an SS (Spread Spectrum) wireless system conforming to the IEEE 802.11 standard. Recently, a 5 GHz band has been opened as a frequency band, and a mode in which a 5 GHz band is used instead of the 2.4 GHz band may be used. The data transmission from the wireless center 2 to the TV main body 3 uses a video compression format of MPEG (Moving Picture Expert Group) 2 to transmit moving image transmission, DVD-Video, and digital broadcast over a communication line exceeding 10 Mbps. Further, transmission of a command (control command including transmission channel change information) between the wireless center 2 and the TV main body 3 is performed by the SS wireless system.

  When applied to an actual application including an encoded stream (bit string) of MPEG video or MPEG audio, and other encoded streams, the encoded streams including synchronization are multiplexed and integrated into one. At the same time, it is necessary to convert the stream into a data format suitable for a unique physical format or protocol of a storage medium, a network, or the like.

  In the MPEG2 system, a program stream (MPEG2-PS, PS: Program Stream) constituting one program and a transport stream (MPEG2-TS, TS: Transport Stream) capable of constituting a plurality of programs as in MPEG1. There is.

  The MPEG stream is a byte stream that has many 1-bit flags but is byte-aligned for each unit such as a header. As a structure common to the entire MPEG system, information indicating the length is preceded in a data portion that is not a fixed length, and when unnecessary, the portion is skipped, or the head of the next data group is checked and reliable. It has a data structure that allows highly-separable separation processing.

  A device that receives a compressed video and audio signal in conformity with the MPEG2 encoding system requires a video and audio sampling frequency on the encoding side to prevent overflow and underflow of video and audio data on the decoding side. And the video and audio sampling frequencies or STC (System Time Clock) on the decoding side.

  Therefore, the decoding apparatus uses PCR (Program Clock Reference: Program Clock Reference) or SCR (System Clock Reference: Reference) defined by the MPEG2 system standard (ISO / IEC standard 13818-1). Thus, the video and audio sampling frequencies on the encoding side match the video and audio sampling frequencies on the decoding side.

  FIG. 2 is a block diagram showing a configuration of the wireless center 2 of the wireless AV system 1.

  In FIG. 2, a wireless center 2 is connected to a BS terminal 11 to receive and select a BS broadcast by a tuning signal, and is connected to a U / VHF antenna terminal 12 to transmit a U / VHF broadcast by a tuning signal. A U / VHF tuner 32 for receiving and selecting a channel, a video / audio demodulator 33 for demodulating a video / audio (AV) signal received and selected by the BS tuner 31 or the U / VHF tuner 32, and an audio switching signal An audio switching unit 34 for switching received audio and information relating to a program such as an EPG (Electrical Program Guide); a video / audio information received by a source selection signal; information relating to the program; 1) 14, video 2 input terminal (decoder input) (external input 2) 15, video 3 input terminal (monitor / BS output shared) (external input 3) And a first selector 35 for selecting external input information from the TV receiver 16, a TV command signal 44 is transmitted and received, the data selected by the first selector 35 is converted into an MPEG2 video compression format, and the TV main body is transmitted by the SS wireless system. 3 and a wireless center for transmitting the tuning signal 41, the voice switching signal 42, the source selection signal 43, etc., and transmitting and receiving the TV command signal 44 to control the entire apparatus. An electrically rewritable nonvolatile memory for storing various data such as a microcomputer (hereinafter referred to as a microcomputer) 37 (transmission channel holding means), a control program of the wireless center microcomputer 37, communication control data, and a transmission channel change program. EEPROM that is a memory (electrically erasable programmable ROM) 38.

  The wireless center 2 includes a plurality of (two in this case) broadcast reception tuners, and at least one of the plurality of BS tuners 31 and the U / VHF tuners may be a tuner capable of receiving terrestrial digital broadcasts.

  The SS transmitting / receiving unit 36 includes an A / D converter 51 for converting the data selected by the first selector 35 into a digital signal, an MPEG2 encoder 52 for converting the data into a video compression format of MPEG2, and transmitting the data by the SS wireless system. An SS wireless transmission / reception engine 53 including an SS wireless device and a wireless control unit for transmission, and a first SS-CPU 54 that controls each unit of the SS transmission / reception unit 36 and detects a radio wave state.

  The SS wireless transmission / reception engine 53 has a transmission function of transmitting an MPEG2 stream or a command to an SS transmission / reception unit 61 (to be described later with reference to FIG. 3) of the TV main body 3, and a transmission / reception of transmitting / receiving a command or the like to / from the SS transmission / reception unit 61. Function.

  Various specifications in the wireless center 2 and the TV main body 3 can be changed by changing a program written in the EEPROM 38. That is, recently, in order to avoid the time loss of changing the mask ROM for each debugging of the system development, the program ROM is a non-volatile memory, for example, an EPROM or an EEPROM, and the program development / correction time is greatly reduced. . Also, if the program is downloaded and the program content of the EEPROM is rewritten, the function can be easily upgraded or changed.

  FIG. 3 is a block diagram showing a configuration of the TV main body 3 of the wireless AV system 1.

  In FIG. 3, the TV main unit 3 transmits and receives the TV command signal 71 to receive the MPEG2 stream and the command transmission data transmitted from the SS transmission / reception unit 36 of the wireless center 2 and decodes the received MPEG2 stream and the like to the original data. A second SS that selects (restores) an SS transmitting / receiving unit 61 (communication means) and data restored by the SS transmitting / receiving unit 61 and an AV signal input from outside via the video 4 input terminal (also used as TV output) 21. It transmits and receives a TV command signal 71 to and from a selector 62, a TV unit 63 (a part of a notifying unit) composed of an LCD or the like for displaying a video signal and outputting an audio signal, a source selection signal 72, an OSD (on-screen A TV microcomputer 64 that transmits the display 73 and the like to control the entire apparatus. An EEPROM 65 which is an electrically rewritable nonvolatile memory for storing various data such as a control program of the TV microcomputer 64, communication control data, and further a transmission channel change program. The remote control device includes a remote control light receiving unit 66 for receiving a control command from a remote control device (not shown) (not shown), a battery 67, and a battery charger microcomputer 68 for controlling charging and discharging of the battery 67.

  The SS transmission / reception unit 61 includes an SS radio transmission / reception engine 81 including an SS radio and a radio control unit for receiving data transmitted by the SS radio system, an MPEG2 decoder 82 for decoding a received MPEG2 stream, and an analog signal And a second SS-CPU 84 (communication state detection means) for controlling each part of the D / A conversion unit 83 and the SS transmission / reception unit 61 for detecting the radio wave state.

  The SS wireless transmission / reception engine 81 has a reception function of receiving an MPEG2 stream or a command from the SS transmission / reception unit 36 of the wireless center 2 and a transmission function of transmitting a command or the like from the SS transmission / reception unit 61.

  In particular, the second SS-CPU 84 detects a radio wave state that detects a communication state between the wireless center 2 and the TV main body 3 (intensity of a radio wave, disturbance of a communication path) by a retransmission request based on an electric field strength of a received radio wave and an error rate. It has a function as a means. Information indicating the detected radio wave state is sent to the TV microcomputer 64 as a TV command signal 71. In the present embodiment, the second SS-CPU 84 of the TV main body 3 has a configuration in which the above-described radio wave state detecting function is provided. However, the first SS-CPU 54 of the wireless center 2 has the same function and detects the detected radio wave. A mode in which information indicating the state is transmitted from the wireless center 2 to the TV main body 3 by a command may be used. Alternatively, both the first SS-CPU 54 and the second SS-CPU 84 may have a radio wave state detecting function. Furthermore, a mode in which the TV microcomputer 64 or the wireless center microcomputer 37 performs the radio wave state detection function may be used.

  The TV microcomputer 64 controls the entire apparatus and, based on the detected communication state, includes information that video and audio data are interrupted, that a transmission channel is being changed, that connection is being established, and that communication is out of range. It has a function as notification means for notifying each message of the reception sensitivity information.

  Further, the TV microcomputer 64 measures the time during which the communication is interrupted, and performs transmission channel change control for holding the transmission channel until a predetermined time has elapsed since the communication was interrupted. A specific example of the transmission channel change control will be described later with reference to FIGS. Further, the TV microcomputer 64 has an OSD generation function unit therein, and displays information such as a channel, time, and volume of a program on a screen of a television or the like. 2. Description of the Related Art In a video device such as a TV and an electronic device such as a video conference system, information such as a channel, time, and volume of a program is generally displayed on a TV screen. The OSD data is stored not in an image but in a format called a bitmap, and the bitmap is converted into YUV format pixel values represented by Y, Cb, and Cr. Is superimposed on the original image. If an image reproducing device such as a DVD (not shown) is connected to the video 4 input terminal (also used for TV output) 21, the OSD can be superimposed on the reproduced image on the display screen. The OSD synthesizing unit 69 (FIG. 4) performs the image superimposition processing of the original image such as the television broadcast and the OSD display.

  As described above, the TV microcomputer 64 displays the channel of the program. Here, the channel of the program is displayed based on information obtained by transmitting and receiving control commands to and from the wireless center 2. That is, the TV microcomputer 64 can display information on the wireless center 2 with which the communication link has been established based on the received control command.

  Although not shown, the TV main body 3 is provided with a speaker, a key input unit, a slot for inserting and removing a card-type external expansion storage medium, and the like. May be directly read. The card-type external expansion storage medium is, for example, a Compact Flash (registered trademark) (CF) including a SRAM (Static RAM) card that holds information written by power backup or a flash memory that does not require power backup, smart media, and memory. Stick, or an ultra-compact hard disk drive (HDD) that is about the same size as CompactFlash (registered trademark) or that can be mounted on a PC card Type II.

  The remote control light receiving unit 66 is an optical communication port using IR (Infrared Rays), and receives an optical signal from a remote control device that performs various operations on the TV body 3 or the wireless center 2. Specifically, it is an I / O port for performing optical communication in accordance with a standard for transmitting data using infrared rays, IrDA (Infrared Data Association), ASK, or the like, or a wireless communication port using radio waves. .

  The battery 67 supplies a predetermined power to each part of the TV main body 3. When the battery 67 becomes chargeable, the battery charger microcomputer 68 detects, for example, that the TV main body 3 is mounted on the wireless center 2 or another cradle or the like, and supplies a power supply terminal ( Charge / discharge control is performed via the respective components (not shown). Specifically, the battery charger microcomputer 68 integrates the discharge current of the battery pack, starts charging when it determines that the remaining capacity of the battery pack has become equal to or less than a predetermined value, and reduces the charging current to the battery pack during charging. The charging is stopped when it is determined that the battery packs have been fully charged and integrated. The charged battery 67 becomes the main power supply of the portable TV when the TV main body 3 is disconnected from the commercial power supply, and supplies electric power to each part of the main body.

  Hereinafter, the operation of the wireless AV system 1 configured as described above will be described.

4 to 7 are diagrams showing state transitions for explaining a transmission channel changing method of the wireless AV system 1. FIG. 4 shows (1) transition at startup, and FIG. 5 shows (2) normal viewing. FIG. 6 shows a transition from (3) reception sensitivity deterioration, and FIG. 7 shows a transition from (4) out of service area. This transmission channel change control is executed by the TV microcomputer 64 of the TV main body 3. In the figure, reference numerals indicate reference numbers (step numbers) for explanation.
(1) Transition at Startup When the power of the TV main body 3 is turned on (S101), "Connecting" is displayed on the TV unit 63 by the OSD output 73 (S102), and the startup is awaited (S103). The display of “connecting” is displayed only when the RC “ON TIMER” and “OFF TIMER” are input. The “Clock not set” display is not displayed at the time of startup.

  When the TV main unit 3 is activated, a channel is selected by receiving a control command from the remote control device (S104). This tuning operation will be described in detail. As shown in FIG. 3, the TV microcomputer 64 which has received the control command from the remote controller transmits a control command related to the tuning to the SS transmitting / receiving unit 61 as a TV command transmitting / receiving signal 71, The SS transmission / reception unit 61 of the TV main body 3 transmits to the SS transmission / reception unit 36 of the wireless center 2 shown in FIG. The SS transmission / reception unit 36 transmits the received control command related to channel selection to the wireless center microcomputer 37 as a TV command transmission / reception signal 44. Upon receiving this control command, the wireless center microcomputer 37 transmits a tuning signal 41 to the BS tuner 31 or the U / VHF tuner 32, and the corresponding tuner 31 or 32 performs tuning. As described above, basically, data is sent from the wireless center 2 to the TV body 3 as an MPEG2 stream by the SS wireless system between the wireless center 2 and the TV body 3, but command transmission is performed between the wireless center 2 and the TV body 3. The command data is transmitted and received by the command. The above is an example of command transmission for channel selection, but similar command transmission is performed for voice and source selection.

  Returning to the description of the transition at the time of (1) startup in FIG. 4, the TV microcomputer 64 determines the communication state between the wireless center 2 and the TV main body 3 detected by the second SS-CPU 84 (the strength of radio waves, It is determined whether or not the reception sensitivity is good based on the information of (interference) (S105). If the reception sensitivity is good, the mute is released (S106), "connected" is erased (S107), and a transition is made to (2) normal viewing (good reception sensitivity) transition state in FIG. 5 (S108). This mute is a non-video / no-sound processing for eliminating noise of video and audio when switching the signal connection.

  As a result, after the power of the TV main unit 3 is turned on, “connected” is displayed on the TV unit 63 by the OSD output 73 until the channel selection is completed. However, since the reception sensitivity is good, the “connected” display is immediately displayed. It disappears and shifts to (2) normal viewing.

  If the receiving sensitivity is not good in the determination in step S105, it is determined whether the receiving sensitivity has deteriorated (S109). If the reception sensitivity is deteriorated, the mute is released (S110), and "the radio wave is difficult to reach" is displayed on the TV unit 63 by the OSD output 73 (S111), and the reception sensitivity deterioration in FIG. (S112).

  If the reception sensitivity is not degraded in the determination in step S109, it is determined that the reception sensitivity is degraded (S113). If the reception sensitivity is degraded, the mute is not released and the OSD output 73 is sent to the TV unit 63 without releasing the mute. "Out of service area" is displayed (S114), and transition is made to (4) Transition from out of service area in FIG. 7 (S115).

As described above, after the TV main unit 3 is turned on, “Connecting” is displayed. If the receiving sensitivity is good, the “Connecting” display disappears. Is out of reach "or" Out of service area "is displayed. Therefore, when switching the transmission channel, the user can easily know whether the connection is being established, the reception state is poor, the video is interrupted, or the communication terminal has changed the transmission channel.
(2) Transition from Normal Viewing (Good Receiving Sensitivity) When in the normal viewing state (S201), when information on the communication state (intensity of radio waves, disturbance of communication path) is input by the second SS-CPU 84. Then, the deterioration of the receiving sensitivity is determined (S202). If the reception sensitivity is degraded, a message “Electric wave is difficult to reach” is displayed on the TV unit 63 by the OSD output 73 (S203), and a transition is made to (3) FIG. S204).

If the reception sensitivity is not degraded in the determination in step S202, it is determined whether the reception sensitivity is degraded (S205). If the reception sensitivity is degraded, mute is performed (S206), "out of service" is displayed on the TV unit 63 by the OSD output 73 (S207), and the state transitions to (4) transition from out of service in FIG. 7 (S208). ). If the reception sensitivity has not deteriorated in the determination in step S205, no transition is made as no change (S209).
(3) Transition from “Electric wave is hard to reach” (Reception sensitivity deterioration) When the reception sensitivity is deteriorated (S301), the reception sensitivity is improved based on the information on the communication state from the second SS-CPU 84. It is determined whether or not it has been performed (S302). If the reception sensitivity has been improved, the display “radio waves are difficult to reach” is erased (S303), and a transition is made from (2) normal viewing (good reception sensitivity) in FIG. 5 (S304).

If the reception sensitivity has not been improved in the determination in step S302, it is determined whether the reception sensitivity has deteriorated (S305). If the reception sensitivity is degraded, the mute is performed (S306), and the display is switched from "it is difficult to reach radio waves" to "out of range" by the OSD output 73 to the TV unit 63 (S307), and (FIG. 7) 4) Transition to a transition state from out of service area (S308). If the reception sensitivity has not deteriorated in the determination in step S305, it is determined whether a predetermined time (here, 10 seconds) has elapsed (S309). After 10 seconds have elapsed, the display “radio waves are difficult to reach” is deleted (S310). If it is other than 10 seconds, it is determined whether the reception sensitivity deterioration state has elapsed for a predetermined time (here, 15 minutes) (S311). If 15 minutes have elapsed, it is determined that the communication has been interrupted and the predetermined time has elapsed. Then, "the radio wave is difficult to reach" is displayed again on the TV unit 63 by the OSD output 73 (S312). If 15 minutes have not elapsed in the determination in step S311, the process is not performed (S313).
(4) Transition from out of service area When the reception sensitivity is degraded due to “out of service area” (S401), it is determined whether or not the reception sensitivity has been improved based on the information on the communication state from the second SS-CPU 84 (S402). ). If the reception sensitivity has been improved, the display is switched to "connecting" because "radio waves are difficult to reach" (S403), and channel selection is performed (S404). The specific operation of channel selection has already been described. Next, the mute is released (S405), "Connecting" is erased (S406), and a transition is made to the transition state of (2) Normal viewing (good reception sensitivity) in FIG. 5 (S407).

  If the reception sensitivity has not been improved or is in a deteriorated state in the determination in step S402, no processing is performed (S408). At this time, the "out of service" display is continued.

  The above-described state transition will be described in more detail by taking a case where a plurality of transceivers exist as an example.

  FIG. 8 is a diagram illustrating transmission and reception of data by a plurality of transceivers A, B, and C, and FIG. 9 is a diagram illustrating an example of using transmission channels of the plurality of transceivers A, B, and C.

  8 and 9, a transmitter A is, for example, the above-described liquid crystal TV wireless center 2, and a receiver A is a TV main body 3. The transmitters B and C are wireless centers of devices other than the above-described liquid crystal TV of the wireless AV system, and the receivers B and C are their portable terminals and the like.

  As a technology for realizing a wireless AV system, for example, there is a standard specification called HAVi (Home Audio / Video Interoperability) Architecture standardized in January 2000. This specification describes how to connect a household appliance or computer and connect another device using one device, as described in the outline section of the HAVi V1.0 Specification version (1.1 Scope of 1 General). Provides an interface to operate. In the HAVi specification, as an example, it is assumed that a network is constructed using home appliances conforming to IEEE 1394 and IEC (International Electrotechnical Commission) 61883. Further, as described in the outline of the specification, all users can freely use devices connected to the network realized by HAVi. As described above, by connecting the AV devices in the home and constructing the AV network, the user can freely use the devices even in remote rooms.

  In addition to such a home AV network, the transceivers A, B, and C are, for example, a mobile phone / PHS (Personal Handy-Phone System) (registered trademark) or a portable information terminal (hereinafter, PDA) for performing wireless communication. (Referred to as “Personal Digital Assistants”).

  On the other hand, a wireless LAN, Bluetooth, and UWB (Ultra Wide Band) are used as a wireless AV system. Wireless LANs are widely used in portable information terminals such as portable notebook personal computers and PDAs having a wireless LAN function. For mobile phones that require lower power consumption, low-power short-range two-way wireless communication systems such as Bluetooth and UWB have attracted attention. Bluetooth is a system that performs short-distance two-way wireless communication between a master (server) and a slave (client), and enables communication between devices anywhere on the earth. Use frequency bands. The communication speed in the current standard is 1 Mbps, and a version upgrade to 2 Mbps is planned in the future. The effective transmission channel rate is synchronous voice communication for up to three transmission channels, or simultaneous transmission of voice and data on one transmission channel. Asynchronous channels support 721 Kbps bi-directional connections and 57.6 Kbps return connections, or symmetric links at 432.6 Kbps.

  FIG. 9 is a diagram illustrating a transmission channel changing method of the wireless AV system. When the wireless AV system complies with the IEEE802.11 standard, the frequencies of 14 transmission channels from transmission channel ch1 to transmission channel ch14 are allocated within the 2.4 GHz band of 2.400 to 2.483 GHz. However, when a plurality of transmission channels are set at the same time in the same area, the frequency interval between adjacent transmission channels is set to 25 MHz or more. This is because the transmitted and received high-frequency signals have a modulated fixed band, so that if the frequencies of adjacent transmission channels are close to each other, the signals of the respective transmission channels will interfere with each other. This is because Therefore, the number of transmission channels that can be set simultaneously in the same area is limited to a maximum of three transmission channels as shown in FIG. 9 as transmission channels A, B, and C (transmission channel C is not shown). As described above, if a wireless LAN system is to be constructed for each house or room in an area where houses are crowded or in a building where rooms are close to each other, a shortage of transmission channels occurs.

  Therefore, in a wireless network, when a transmitter and a receiver are communicating with a specific frequency (transmission channel), when the same transmission channel is used by another transmitter and receiver pair, the transmission channel is used later. It is necessary to change the transmission device to a vacant transmission channel.

  In the example of FIG. 9, the transmitter A performs packet communication with the receiver A using the transmission channel A. At this time, when the transmitter B attempts to perform communication, the transmitter A uses the transmission channel A, and the transmitter B uses the transmission channel B other than the transmission channel A to communicate with the receiver B. Packet communication will be performed. Here, when the transmitter C further attempts to perform communication, since the transmitter A uses the transmission channel A and the transmitter B uses the transmission channel B, the communication using the transmission channel C other than the transmission channels A and B is performed. Will be done.

  However, from the viewpoint of the transmitter C, it may not be easily determined whether or not another transmitter (for example, the transmitter A) is performing packet communication. That is, when the stream is not transmitted for some reason in the transmitter A (for example, when the video is stopped by pressing the stop button), the transmitter C determines that the transmission channel A is empty and the transmitter C transmits the stream without permission. When starting to use channel A, if transmitter A communicates again, transmitter A has to go looking for a new transmission channel because transmission channel A has been used by transmitter C. Switching of the transmission channel may require about 3 seconds because processing such as initialization is included.

  Originally, the stream is interrupted while the transmission channel is being changed. Therefore, in the present embodiment, as described in detail with reference to FIGS. 4 to 7, when the communication state is interrupted, for example, when switching the transmission channel, it is determined whether the video has been interrupted or the transceiver has changed the transmission channel. , "Connecting", "Searching for a transmission channel", "Electric wave is difficult to reach", "Out of service", etc. (message by display, message by voice, or any combination thereof) In addition, it is possible to prevent the user from feeling uncomfortable.

  Further, in the present embodiment, control is performed to measure the time when communication is interrupted in a certain transmission channel, and to judge that the transmission channel is in use when the time when communication is interrupted is within a predetermined set timeout time. . This control is performed by the control unit of the transceiver. For example, in the case of the wireless AV system shown in FIGS. 1 to 3, the wireless center microcomputer 37 and / or the TV microcomputer 64 execute the control. Note that the process of measuring the time during which communication is interrupted and the process of determining that the device is in use are performed by the control unit of the device that attempts to interrupt the transmission channel.

  In the example of FIG. 9, when the transmitter A performs packet communication with the receiver A using the transmission channel A, and the transmitter B attempts to perform communication, the transmitter A uses the transmission channel A. Therefore, the transmitter B performs packet communication with the receiver B using the transmission channel B which is a transmission channel other than the transmission channel A. Here, at the time shown in FIG. 9, when the transmitter C further attempts to perform communication, the packet communication of the transmitter A and the packet communication of the transmitter B are interrupted, but both are within the set timeout time. Both the transmission channel A and the transmission channel B are determined to be in use, and the transmission channel A or the transmission channel B is not used by the transmitter C. As a result, frequent switching of the transmission channel can be prevented beforehand, and an optimal communication state can be maintained in the entire network.

  Next, a method of detecting “out of service area” will be described with reference to FIGS. Note that this detection processing is executed by the first SS-CPU in the wireless center 2 and by the second SS-CPU in the TV main body 3, but is executed by the wireless center microcomputer 37 and / or the TV microcomputer 64, respectively. You may.

  FIG. 11 shows signals transmitted and received between a transmitter corresponding to the wireless center 2 and a receiver corresponding to the TV main body 3. Here, the confirmation signal is a signal transmitted to confirm the presence of the other party. The ACK signal is a signal indicating that the acknowledgment signal has been received, and is a signal transmitted when the acknowledgment signal is received. Further, the confirmation signal may be a command signal. Since the bidirectional communication is performed as described above, the transmitting side can grasp the receiving state by checking the state of the data.

  In the example of FIG. 11, the ACK signal is transmitted for each acknowledgment signal. However, after the receiver receives the acknowledgment signal once, the ACK signal is transmitted periodically without receiving the acknowledgment signal. Alternatively, the acknowledgment signal may be completely omitted, and the ACK signal may be transmitted periodically without receiving the acknowledgment signal.

  FIG. 12 shows processing on the side that receives the confirmation signal (in this case, the receiver). First, the count is set to 0 (S1201), and a predetermined time (T seconds) is waited (S1202). Then, it is determined whether a confirmation signal has been received while waiting for a certain time (S1203). If a confirmation signal has been received (YES in S1203), an ACK signal is transmitted (S1204). On the other hand, if the confirmation signal has not been received (NO in S1203), the count is incremented by 1 (S1205). Next, the count value is compared with a predetermined value (S1206). If the count value is smaller than the predetermined value (NO), the process returns to the process of waiting for a certain time (S1202). On the other hand, if the count value has exceeded the predetermined value (YES in S1206), it is determined that the mobile phone is out of the service area (S1207).

  Here, the predetermined value is a value related to the time T of the process of waiting for a predetermined time, and T seconds × the predetermined value is set to about 5 seconds. Note that the value of the predetermined value is not limited to this, and an optimal value can be selected according to the situation.

  FIG. 13 shows an example in which processing equivalent to that of FIG. 12 is realized by another means. First, the current time (T0) is recorded (S1301), and a predetermined time (T seconds) is waited (S1302). Then, it is determined whether or not the confirmation signal has been received while waiting for a certain time (S1303). If a confirmation signal has been received (YES in S1303), an ACK signal is transmitted (S1304). On the other hand, if the confirmation signal has not been received (NO in S1303), the current time (T1) is recorded (S1305). Next, the difference value between T1 and T0 is compared with a predetermined value (S1306). If the difference value is smaller than the predetermined value (NO), the process returns to the process of waiting for a certain time (S1302). On the other hand, if the difference value exceeds the predetermined value (YES in S1306), it is determined that the mobile phone is out of the service area (S1307).

  The above processing procedure is processing on the side receiving the confirmation signal. Next, processing on the side receiving the ACK signal will be described.

  As shown in FIG. 14, first, the count is set to 0 (S1401), and a predetermined time (T seconds) is waited (S1402). Next, a confirmation signal is transmitted (S1403). Next, it is determined whether an ACK signal has been received (S1404). If an ACK signal has been received (YES in S1404), the process returns to step S1401. On the other hand, if no ACK signal has been received (NO in S1404), the count is incremented by 1 (S1405). Next, the count value is compared with a predetermined value (S1406). If the count value is smaller than the predetermined value (NO), the process returns to the process of waiting for a certain time (S1402). On the other hand, if the count value exceeds the predetermined value (YES in S1406), it is determined that the mobile phone is out of the service area (S1407).

  FIG. 15 shows an example in which the same processing as in FIG. 14 is realized by another procedure. First, the current time (T0) is recorded (S1501), and a predetermined time (T seconds) is waited (S1502). Next, a confirmation signal is transmitted (S1503). Next, it is determined whether an ACK signal has been received (S1504). If an ACK signal has been received (YES in step S1504), the process returns to step S1501. On the other hand, if the ACK signal has not been received (NO in S1504), the current time (T1) is recorded (S1505). Next, the difference value between T1 and T0 is compared with a predetermined value (S1506). If the difference value is smaller than the predetermined value (NO), the process returns to the process of waiting for a certain time (S1502). On the other hand, when the difference value exceeds the predetermined value (YES in S1506), it is determined that the mobile phone is out of the service area (S1507).

  As described above, in the wireless AV system 1, the transmitter and the receiver respectively detect the ACK signal / confirmation signal from the other party, and determine that they are out of the service area when the ACK signal / confirmation signal does not return.

  Next, an example of a procedure for classifying a communication state into “good”, “deteriorated”, “deteriorated”, and “out of service” based on an error rate or the like will be described with reference to FIG. Note that this detection process is executed by the second SS-CPU 84 of the TV main body 3, but may be executed by the TV microcomputer 64.

  First, the packet error rate is compared with a predetermined threshold (first threshold) Th1 (S1601). The packet error rate is an error rate included in a received packet. When the packet error rate is smaller than the threshold Th1 (YES in S1601), the communication state is determined to be “good” (S1602). The threshold value Th1 can be set to, for example, about 0.001. However, the present invention is not limited to this, and an optimal value can be selected according to the situation.

  Next, if the packet error rate is larger than the threshold Th1 (NO in S1601), the number of retransmissions is compared with a predetermined threshold (second threshold) Th2 (S1603). The number of retransmissions is the number of times a packet is retransmitted when the packet error rate is high and the packet cannot be repaired. If the number of retransmissions is smaller than the threshold Th2 (YES in S1603), the communication state is determined to be "deteriorated" (S1604). Here, it is preferable that the threshold value Th2 is set to an upper limit value that does not disturb the image. In this case, “deterioration” of the communication state indicates a state in which the video is disturbed. The threshold value Th2 can be set to, for example, about 3. However, the present invention is not limited to this, and an optimal value can be selected according to the situation.

  Next, when the number of transmissions is greater than the threshold Th2 (NO in S1603), it is determined whether the mobile phone is out of the service area (S1605). The out-of-service area can be determined by the procedure shown in FIGS. 12 and 13 as described above. That is, a "confirmation signal" transmitted by the wireless center 2 to confirm the existence of the TV main unit 3 as a communication partner, or an "ACK signal" transmitted by the TV main unit 3 that has received the confirmation signal is transmitted on the receiving side for a predetermined time. It can be performed by monitoring whether or not it can be received. If it is determined that the communication state is not out of the service area (NO in S1605), the communication state is determined to be “deteriorated” (S1606). On the other hand, if it is out of the service area, the communication state is finally determined to be "out of service area" (S1607).

  In FIG. 16, although the determination is made using the packet error rate and the number of retransmissions (S1601, S1603), the communication state may be determined using only the packet error rate and comparing it with a two-stage threshold value. Good. Similarly, the communication state may be determined by using only the number of retransmissions and comparing it with a two-stage threshold. It is needless to say that a more detailed determination can be made by comparing with not only two steps but also more threshold values. Therefore, for example, it is also possible to combine the two-stage determination using the packet error rate and the two-stage determination using the number of retransmissions.

  Also, the case has been described where the radio wave reception state is detected by “error rate” and “number of retransmission requests based on the error rate”. In addition, “electric field strength”, “temporal change of error rate”, and “electric field strength "Temporal change", "Temporal change in the number of retransmission requests" and the like can be used as parameters. In particular, in the power saving mode for suppressing power consumption, it is preferable to determine the radio wave state based on the electric field strength in a state where no video and / or audio data is transmitted and received.

  Next, transmission channel change processing and transmission channel change determination will be described with reference to FIGS. Note that these processes are executed by the first SS-CPU in the wireless center 2 and by the second SS-CPU in the TV main body 3, and are executed by the wireless center microcomputer 37 and / or the TV microcomputer 64, respectively. You may.

  As shown in FIG. 17, the transmitter (wireless center 2) first determines whether to change the transmission channel (S1701). The transmission channel change determination is made under conditions such that the out-of-service state continues for a certain period of time or longer. If the result of the transmission channel change determination is YES (YES in S1701), the communication state becomes “searching for a channel”, and the transmission channel is changed (S1702).

  Here, it is assumed that there are three transmission channels “transmission channel A”, “transmission channel B”, and “transmission channel C” as channels used in wireless transmission. The order of change of the transmission channels is to be changed in the order of transmission channel A → transmission channel B → transmission channel C → transmission channel A →. For example, when the current transmission channel is the transmission channel B, it means that the transmission channel is changed to the transmission channel C by the process of step S1702.

  Next, a confirmation signal is transmitted (S1703). Next, it is determined whether an ACK signal has been received (S1704). If an ACK signal is received from the receiver (YES in S1704), the transmission channel is fixed and the subsequent communication is performed. At this time, the communication state changes from “searching for a transmission channel” to “good”.

  On the other hand, if the ACK signal cannot be received from the receiver (NO in S1704), the elapsed time after the change of the transmission channel is compared with the predetermined time TS (S1705). When the elapsed time is shorter than the predetermined time TS (NO in S1705), the process returns to the process of transmitting the confirmation signal (S1703). On the other hand, if the elapsed time is longer than the predetermined time TS (YES in S1705), the process returns to the process of changing the transmission channel (S1702).

  Subsequently, the processing in the receiver (TV main body 3) will be described similarly.

  First, a transmission channel change determination is performed (S1711). If the result of the channel change determination is YES (YES in S1711), the communication state becomes “searching for a transmission channel”, and the transmission channel is changed (S1712).

  Next, it is determined whether a confirmation signal has been received from the transmitter (S1713). If a confirmation signal is received from the transmitter (YES in S1713), the channel is fixed, an ACK signal is transmitted to the transmitter (S1714), and subsequent communication is performed. At this time, the communication state changes from “searching for a transmission channel” to “good”.

  On the other hand, if the confirmation signal cannot be received from the transmitter (NO in S1713), the elapsed time after the channel change is compared with the predetermined time TJ (S1715). When the elapsed time is shorter than the predetermined time TJ (NO in S1715), the process returns to the process of determining whether to receive the confirmation signal (S1713). On the other hand, if the elapsed time is longer than the predetermined time TJ (YES in S1715), the process returns to the process of changing the transmission channel (S1712).

  Here, by setting the predetermined time TJ of the receiver to be longer than the predetermined time TS of the transmitter, an opportunity to communicate on the same channel is obtained even if the transmitter and the receiver simultaneously perform the process of changing the transmission channel. For example, when the three transmission channels A, B, and C are sequentially changed, it is preferable that the predetermined time TJ> the predetermined time TS × 3.

  FIG. 18 is an explanatory diagram showing an example of timing when a transmitter and a receiver simultaneously change transmission channels when there are three transmission channels A, B, and C. As shown in the figure, the transmitter changes the transmission channel from transmission channel A to transmission channel B to transmission channel C every predetermined time TS, and the receiver changes transmission channel C to transmission channel A every predetermined time TS. → The transmission channel B and channel are changed. Here, the predetermined time TJ> the predetermined time TS × 3.

  When the transmitter has transmitted the acknowledgment signal on transmission channels A and B, the receiver has selected transmission channel C. Therefore, the confirmation signal does not reach the receiver because the transmission channels are different. Thereafter, when the transmitter sends an acknowledgment signal on transmission channel C, the receiver is still selecting transmission channel C. Thus, because the transmission channels match, the receiver receives the acknowledgment signal and sends an ACK signal to the transmitter. As a result, communication between the transmitter and the receiver is established on the transmission channel C.

  Note that the wireless center 2 and the TV main body 3 of the wireless AV system 1 may detect and report the communication state based on video and / or audio data, or may perform detection and notification based on a control command including transmission channel change information. May go. The same message is used to notify the transmission state of video and / or audio data or a control command (that is, “confirmation signal” or “ACK signal” in FIG. 11). Then, when the transmission state of any one of the video data, the audio data, and the control command deteriorates, a notification message is displayed. Examples of broadcast messages are "out of service area" when radio waves are no longer reachable, "radio waves are difficult to reach" when radio wave conditions are poor, and " I am looking for it. "When I find a transmitter to communicate with and set up a connection," Connecting "etc. is displayed.

  Here, the transmission channel is changed by a control command including “transmission channel change information” or by the communication state (communication is interrupted) of the confirmation signal and the ACK signal as described above.

  The former corresponds to a case where a specific transmission channel is set by a user operation. The transmission channel change information includes information on which transmission channel to change. On the other hand, the latter corresponds to a case where the user's setting is, for example, "AUTO (automatic)" and a vacant transmission channel is searched.

  As described above, the wireless AV system 1 according to the present embodiment includes the wireless center 2 as a base device and the TV main unit 3 as a wireless terminal. An SS transmission / reception unit 61 for receiving the MPEG2 stream and the command transmission data transmitted from the unit 36 and decoding the received MPEG2 stream and the like; a TV unit 63 for displaying a video signal and outputting an audio signal; And a second SS-CPU 84 for detecting a communication state between the wireless center 2 and the TV main unit 3 in response to a retransmission request based on the electric field strength of a received radio wave and an error rate. The video and audio data is interrupted based on the Each message of receiving sensitivity information including that the channel is being changed, being connected, and out of communication range is displayed on the TV unit 63 by OSD. Therefore, when the transmission channel is switched or the communication condition is interrupted due to poor radio wave condition. Even so, an appropriate message indicating the transmission status will be displayed, and the user may have a poor communication condition due to whether the video has been interrupted, the communication terminal has changed the transmission channel, or an interfering radio wave such as using a microwave oven. It is possible to easily know whether the problem has occurred, and it is possible to eliminate the user's discomfort. For example, since a message such as "Connecting" is displayed by the OSD display even when the video is not displayed, the user can intuitively understand the reason why the video is not displayed and wait until the video is displayed, It is possible to prevent useless transmission channel operation for avoiding a state in which no video is displayed. By avoiding useless transmission channel operation by the user, the time until video display can be further reduced.

  In the present embodiment, as described in (4) Transition from out of service area in FIG. 7, the content of the message is changed according to the communication state, so that the user can know the transition of the communication state. These messages are examples, and any content may be notified at any step. For example, when deterioration or recovery of the communication state can be expected, it is easier to understand if the approximate time until the video is displayed and the image character indicating the time are notified.

  Also, when the reception condition is deteriorating, the user is prompted to take the next action guideline (for example, "Reception condition is getting worse. Please move to a place where radio waves are easy to reach." Please get away from obstacles such as microwave ovens. ") If you make announcements by display / voice, a more friendly system will be achieved.

  In the present embodiment, a message indicating the transmission status of video and audio data and the like is displayed on the TV unit 63 by OSD so as to notify the transmission status message of video and audio data and the like. The notification may be performed by voice using the information, or may be performed in combination. In addition, any display method is not limited to the OSD display.

  Further, in the present embodiment, the time when the communication is interrupted is measured, and the transmission channel is held until a predetermined time elapses after the communication is interrupted, so that the transmission channel is frequently switched. It is possible to prevent communication and maintain an optimal communication state in the entire network.

  It should be noted that the wireless AV system of the present invention is not limited to the above-described embodiment, and it is needless to say that various changes can be made without departing from the scope of the present invention. For example, a portable TV is used as a wireless AV device, but the present invention is not limited to a TV receiver, and can be applied to a device having a wireless communication function or an integrated device thereof. For example, in addition to a VTR (Video Tape Recorder), a recording / reproducing device for recording on an HDD or DVD may be used as the AV device. Further, as a device capable of transmitting and receiving data, a device integrated with an information device function represented by a personal computer may be used, and is applicable to all systems. Further, the content of the transmission / reception data may be any.

  Further, in the present embodiment, a TV receiver has been described, but the present invention is not limited to this, and as described above, the present invention can be applied to a tuner and a personal computer, or other AV equipment using the tuner.

  In addition, the type of each processing unit and the like of the wireless AV system and the type and format of the setting information are not limited to the above-described embodiments.

  Further, as the tuners, two broadcasts, a BS tuner and a U / V tuner, are taken as examples, but the types and number of broadcasts such as CS tuners are not limited to these.

  Although the names of the wireless communication device and the wireless AV system are used in the present embodiment, this is for convenience of explanation, and may be a wireless communication device, an AV device, a broadcast station selection device, or the like.

  Further, in the present embodiment, a configuration has been described in which the “notification unit” is provided on the receiving side (TV main body 3), but may be provided on the transmitting side (wireless center 2) by a display panel, an LED, or the like. That is, the wireless AV system according to the present invention may have a configuration in which the notifying unit for notifying the receiving status on the receiving side is provided on either the transmitting side or the receiving side. However, it is desirable to detect the communication state on the receiving side (TV main body 3).

  The wireless AV system described above is also realized by a program for causing each device constituting the wireless AV system to function. This program is stored in a computer-readable recording medium. In the present invention, as the recording medium, the main memory itself may be a program medium, or a program reading device is provided as an external storage device, and the program medium can be read by inserting the recording medium into the program reading device. You may. In any case, the stored program may be configured to be accessed and executed by the CPU, or the program may be read in any case, and the read program may be stored in a program storage area (not shown). And the program may be executed. It is assumed that this download program is stored in the main unit in advance.

  Here, the program medium is a recording medium configured to be separable from the main body, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (registered trademark) disk or a hard disk, or a CD-ROM / MO / It may be a disk system of an optical disk such as an MD / DVD, a card system such as an IC card / optical card, or a fixed medium including a semiconductor memory such as a mask ROM, EPROM, EEPROM, or flash ROM. .

  Further, although not shown, when a device capable of connecting to an external communication network is provided, the program is fluidly loaded so that the program is downloaded from the communication network via the communication connection device. Media. When the program is downloaded from the communication network as described above, the download program may be stored in the main device in advance, or may be installed from another recording medium. The content stored in the recording medium is not limited to a program, but may be data.

  Note that the present embodiment does not limit the scope of the present invention, and various changes can be made within the scope of the present invention. For example, the present embodiment can be configured as follows.

  Further, the wireless terminal of the present invention includes a communication unit for transmitting / receiving a control command including video and / or audio data or transmission channel change information to / from the base device; a communication state detection unit for detecting a communication state; Notification means for notifying reception sensitivity information based on the communication state detected by the means.

  Further, the wireless terminal of the present invention includes a communication unit for transmitting / receiving a control command including video and / or audio data or transmission channel change information to / from the base device; a communication state detection unit for detecting a communication state; Notification means for notifying at least the transmission status of the video and / or audio data based on the communication state detected by the means.

  Further, the wireless terminal of the present invention may include a transmission channel holding unit that measures a time when communication is interrupted and holds a transmission channel until a predetermined time has elapsed after the communication is interrupted.

  Further, in the wireless terminal according to the present invention, the communication state detecting means detects a communication state based on at least one of an electric field strength of a received radio wave, an error rate, and the number of retransmission requests based on the error rate. You may.

  Further, in the wireless terminal according to the present invention, the communication state detecting means may detect a communication state with a base device with which a communication link has been established.

  Further, in the wireless terminal according to the present invention, the notifying means may include a reception sensitivity including that the video and / or audio data is interrupted, that a transmission channel is being changed, that the connection is being established, and that the communication is out of the communication range. Any one or more of the information may be reported.

  Further, the wireless terminal of the present invention includes communication means for transmitting / receiving a control command including video and / or audio data or transmission channel change information to / from the base device, and the communication means is detected by the base device. The communication device may receive information indicating a communication state from a base device, and may include a notification unit that notifies reception sensitivity information based on the information indicating the communication state received by the communication unit.

  Further, in the wireless terminal according to the present invention, the notifying unit may display a message by a display unit or generate a message by a voice output unit.

  In addition, the wireless terminal of the present invention includes communication means for transmitting / receiving a control command including video and / or audio data or transmission channel change information to / from the base device, measures a time during which communication has been interrupted, and interrupts the communication. A transmission channel holding means for holding a transmission channel until a predetermined time elapses after that may be provided.

  Further, in the wireless terminal according to the present invention, the communication unit may transmit the video and / or audio data or the control command by a spread spectrum wireless system.

  Furthermore, in the wireless terminal according to the present invention, the communication means may perform wireless LAN or low-power short-range two-way wireless communication such as Bluetooth and UWB (Ultra Wide Band).

  Further, in the wireless terminal according to the present invention, the communication means may transmit the video and / or audio data by using an MPEG stream conforming to the MPEG2 coding scheme.

  Furthermore, the wireless terminal of the present invention, at least, displays a video signal based on the received video data, and / or, based on the received control command to display information of the base device with which a communication link has been established, display A device may be provided.

  Further, the base device of the present invention may transmit and receive a control command including video and / or audio data or transmission channel change information to and from the above-mentioned wireless terminal.

  Further, the base device of the present invention may include a communication state detecting means for detecting a communication state, and transmit information indicating the communication state detected by the communication state detecting means to the wireless terminal.

  Further, in the base device of the present invention, the input video and / or audio data may be external data.

  Furthermore, in the base device of the present invention, the input video and / or audio data may be data from a broadcast receiving tuner.

  Further, the wireless system of the present invention may be configured to include the wireless terminal described above and a base device that transmits and receives a control command including video and / or audio data or transmission channel change information to and from the wireless terminal.

  In addition, the method for controlling a wireless terminal according to the present invention is a method for controlling a wireless terminal configuring a wireless system in which a wireless terminal and a base device are connected through a wireless network, and includes a method for changing video and / or audio data or a transmission channel. A method of transmitting and receiving a control command including information to and from the base device, detecting a communication state, and notifying reception sensitivity information based on the detected communication state may be employed.

  In addition, the method for controlling a wireless terminal according to the present invention is a method for controlling a wireless terminal configuring a wireless system in which a wireless terminal and a base device are connected through a wireless network, and includes a method for changing video and / or audio data or a transmission channel. A method of transmitting and receiving a control command including information to and from a base device, detecting a communication state, and notifying at least a transmission state of the video and / or audio data based on the detected communication state may be employed.

  In addition, the method for controlling a wireless terminal according to the present invention is a method for controlling a wireless terminal configuring a wireless system in which a wireless terminal and a base device are connected through a wireless network, and includes a method for changing video and / or audio data or a transmission channel. A control command including information is transmitted / received to / from the base device, information indicating a communication state detected by the base device is received from the base device, and reception sensitivity information is reported based on the information indicating the communication state. It may be a method.

  In addition, the method for controlling a wireless terminal according to the present invention is a method for controlling a wireless terminal configuring a wireless system in which a wireless terminal and a base device are connected through a wireless network, and includes a method for changing video and / or audio data or a transmission channel. A method may be used in which a control command including information is transmitted to and received from the base device, the time during which communication is interrupted is measured, and the transmission channel is held until a predetermined time has elapsed since the communication was interrupted.

  Further, the control program for a wireless terminal according to the present invention may be a control program for operating the above-described wireless terminal, and may be a program for causing a computer to function as each of the above-described units.

  Further, a computer-readable recording medium according to the present invention stores the above-described control program for a wireless terminal.

  Also, the wireless terminal according to the present invention includes a communication unit for transmitting / receiving a control command including video and / or audio data or transmission channel change information to / from the base device; a communication state detection unit for detecting a communication state; Notification means for notifying at least the transmission status of the control command based on the communication state detected by the detection means may be provided.

  In addition, a method for controlling a wireless terminal according to the present invention is a method for controlling a wireless terminal constituting a wireless system in which a wireless terminal and a base device are connected through a wireless network, wherein the method includes controlling video and / or audio data or transmission channels. A method may be used in which a control command including change information is transmitted / received to / from a base device, a communication state is detected, and at least a transmission state of the control command is reported based on the detected communication state.

  According to the above configuration, the transmission status of the control command transmitted and received between the wireless terminal and the base device can be reported. As this control command, for example, a “confirmation signal” transmitted by the base device to confirm the presence of the wireless terminal with which the base device communicates, an “ACK signal” transmitted by the wireless terminal that has received the confirmation signal, and the like can be used. . Then, when the transmission state of the control command deteriorates, the wireless terminal notifies the user by displaying a notification message or the like. The notification message may be, for example, "out of service area" when radio waves are no longer reachable, "radio waves are difficult to reach" when radio wave conditions are poor, or "transmitter when searching for a transmitter to communicate by changing the transmission channel. "While searching for a transmitter to communicate with, and setting the connection," Connecting "may be displayed.

  Therefore, according to the wireless terminal, even when the display of the video is interrupted due to a change in the transmission channel or the like, it is possible to prevent the user from feeling uncomfortable, and to improve the usability of the user.

  Further, the wireless terminal according to the present invention may include a transmission channel holding unit that measures a time when the communication is interrupted, and holds the transmission channel until a predetermined time elapses after the communication is interrupted.

  According to the above configuration, furthermore, frequent switching of the transmission channel can be prevented, and the optimal communication state can be maintained as much as possible in the entire network.

  Further, in the wireless terminal according to the present invention, the communication state detecting means detects a communication state based on at least one of an electric field strength of a received radio wave, an error rate, and the number of retransmission requests based on the error rate. There may be.

  According to the wireless terminal, the electric field strength of the received radio wave, the error rate, and the number of retransmission requests based on the error rate can be suitably used as the parameters for detecting the communication state. Further, by combining a plurality of types of parameters, it is possible to more effectively detect a communication state.

  Further, in the wireless terminal according to the present invention, the communication state detection means may detect a communication state with a base device with which a communication link has been established.

  According to the above configuration, it is possible to further detect the communication state with the base device with which the communication link has been established.

  Further, in the wireless terminal according to the present invention, the notifying unit may receive the video and / or audio data indicating that the video and / or audio data is interrupted, that the transmission channel is being changed, that the connection is being made, and that the communication is out of the communication range. Any one or more of the sensitivity information may be reported.

  According to the above configuration, further, any one of the reception sensitivity information including that the video and / or audio data is interrupted, that the transmission channel is being changed, that the connection is being made, and that it is out of the communication range. One or more can be announced.

  Further, in the wireless terminal according to the present invention, the notifying unit may display a message on a display unit or sound a message on a voice output unit.

  According to the above configuration, furthermore, information of various contents indicating the communication state can be appropriately presented to the user by message display or message pronunciation.

  Furthermore, the wireless terminal according to the present invention, when changing the transmission channel, transmits all transmission channels during a period equal to or longer than a period during which the base device loops over all transmission channels, or during a period when the wireless terminal holds one transmission channel. The transmission channel may be switched at any timing in the cycle of making a round.

  According to the above configuration, further, when the wireless terminal and the base device change the transmission channel at the same time, and can always find a matching transmission channel, the communication can be established by changing the transmission channel. Becomes possible.

  Further, in the wireless terminal according to the present invention, the communication means may transmit the video and / or audio data or the control command by a spread spectrum wireless system.

  The wireless terminal is further suitable for a spread spectrum wireless communication device.

  Further, in the wireless terminal according to the present invention, the communication means may perform wireless LAN or low-power short-range two-way wireless communication such as Bluetooth and UWB (Ultra Wide Band).

  The wireless terminal is further suitable for a wireless communication device for performing low-power short-range two-way wireless communication such as wireless LAN or Bluetooth and UWB (Ultra Wide Band).

  Further, in the wireless terminal according to the present invention, the communication means may transmit the video and / or audio data by using an MPEG stream conforming to the MPEG2 coding scheme.

  The wireless terminal is further suitable for a wireless communication device that transmits the video and / or audio data using an MPEG stream conforming to the MPEG2 encoding scheme.

  Furthermore, the wireless terminal according to the present invention may include a display device that displays a video signal based on the received video data.

  The wireless terminal further includes a display device and displays a video signal based on the received video data, and is suitable for, for example, a display-separated type wireless TV receiver.

  Further, in the wireless terminal according to the present invention, the communication state detecting means may determine whether or not an image displayed on the display device is disturbed.

  According to the above configuration, it is further possible to detect a case where the image displayed on the display device is disturbed and notify the user of a warning.

  Further, the base device according to the present invention may transmit and receive a control command including video and / or audio data or transmission channel change information to and from the above-mentioned wireless terminal.

  According to the above configuration, it is possible to realize a base device that transmits and receives a control command including video and / or audio data or transmission channel change information to and from the above-described wireless terminal.

  Furthermore, the base device according to the present invention may include a communication state detection unit that detects a communication state, and transmits information indicating the communication state detected by the communication state detection unit to the wireless terminal. .

  According to the above configuration, it is possible to further transmit information indicating the communication state to the wireless terminal. Therefore, the wireless terminal can notify the user of the communication state based on the communication state detected by the base device.

  Further, the base device according to the present invention, when changing the transmission channel, transmits all transmission channels during a period equal to or longer than a period during which the wireless terminal loops through all transmission channels or during a period during which the wireless terminal holds one transmission channel. The transmission channel may be switched at any timing of a cycle of making a round.

  According to the above configuration, further, when the wireless terminal and the base device change the transmission channel at the same time, and can always find a matching transmission channel, the communication can be established by changing the transmission channel. Becomes possible.

  Further, in the base device according to the present invention, the input video and / or audio data may be data from a broadcast receiving tuner.

  The base device is further suitable for, for example, a center device of a display-separated type wireless TV receiver for transferring video and / or audio data input from a broadcast receiving tuner to a wireless terminal.

  Further, a wireless system according to the present invention may include the above-described wireless terminal and a base device that transmits and receives a control command including video and / or audio data or transmission channel change information to and from the wireless terminal.

  According to the above configuration, the transmission status of the control command transmitted and received between the wireless terminal and the base device can be reported. Therefore, according to the wireless terminal, even when the display of the video is interrupted due to a change in the transmission channel or the like, it is possible to prevent the user from feeling uncomfortable, and to improve the usability of the user.

  Note that the wireless terminal may be realized by a computer. In this case, a computer readable recording of a wireless terminal control program that causes the computer to realize the wireless terminal by operating the computer as each of the above-described units. Recording media also fall within the scope of the present invention.

  The wireless system of the present invention is suitable for, but not limited to, a home AV network system such as a display-separated type wireless TV receiver for wirelessly transmitting video and / or audio data. The present invention is widely applicable to wireless communication devices such as a PHS (Personal Handy-Phone System) (registered trademark) and a personal digital assistant (PDA (Personal Digital Assistants)).

FIG. 1 is a block diagram illustrating a configuration of a wireless AV system according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating a configuration of a wireless center of the wireless AV system illustrated in FIG. 1. FIG. 2 is a block diagram illustrating a configuration of a TV main body of the wireless AV system illustrated in FIG. 1. FIG. 2 is a state transition diagram for explaining a transmission channel changing method in the wireless AV system shown in FIG. 1. FIG. 2 is a state transition diagram for explaining a transmission channel changing method in the wireless AV system shown in FIG. 1. FIG. 2 is a state transition diagram for explaining a transmission channel changing method in the wireless AV system shown in FIG. 1. FIG. 2 is a state transition diagram for explaining a transmission channel changing method in the wireless AV system shown in FIG. 1. FIG. 2 is a diagram illustrating transmission and reception of data by a plurality of transceivers A, B, and C of the wireless AV system illustrated in FIG. 1. FIG. 2 is a diagram illustrating an example of using transmission channels of a plurality of transceivers A, B, and C in the wireless AV system shown in FIG. 1. FIG. 2 is an explanatory diagram schematically showing the wireless AV system shown in FIG. 1. FIG. 2 is an explanatory diagram showing control commands transmitted and received between a wireless center of the wireless AV system shown in FIG. 1 and a TV main body. 3 is a flowchart showing a process of determining “out of service” in the TV main body of the wireless AV system shown in FIG. 1. 3 is a flowchart showing a process of determining “out of service” in the TV main body of the wireless AV system shown in FIG. 1. 2 is a flowchart showing a process of determining “out of service” in a wireless center of the wireless AV system shown in FIG. 1. 2 is a flowchart showing a process of determining “out of service” in a wireless center of the wireless AV system shown in FIG. 1. 2 is a flowchart illustrating a communication state determination process in a TV main body of the wireless AV system illustrated in FIG. 1. 2 is a flowchart showing a transmission channel change process in a wireless center and a TV main body of the wireless AV system shown in FIG. 1. FIG. 2 is an explanatory diagram showing an example of transmission channel change by a wireless center and a TV main body of the wireless AV system shown in FIG. 1.

Explanation of reference numerals

1 wireless AV system 2 wireless center unit (wireless center) (base equipment, wireless communication device, center device)
3 Television main unit (TV main unit) (wireless terminal, wireless communication device, display device)
11 BS terminal 12 U / VHF antenna terminal 13 Diversity terminal 14 Video 1 input terminal (with S terminal)
15 Video 2 input terminal (decoder input)
16 Video 3 input terminal (for both monitor / BS output)
17 AC power supply section 18 Car-DC power supply section 21 Video 4 input terminal (shared with TV output)
22 AC power supply unit 23 Car-DC power supply unit 31 BS tuner 32 U / VHF tuner 33 Video / audio demodulation unit 34 Audio switching unit 35 First selector 36 SS transmission / reception unit (communication means)
37 Wireless Center Microcomputer (Wireless Center Microcomputer)
(Transmission channel holding means)
38,65 EEPROM
51 A / D converter 52 MPEG2 encoder 53 SS wireless transmission / reception engine 54 SS-CPU (communication state detecting means)
61 SS transmission / reception unit (communication means)
62 second selector 63 TV unit (part of notification means)
64 TV microcomputer (part of notification means, transmission channel holding means)
66 Remote control light receiving section 67 Battery 68 Battery charger microcomputer 81 SS wireless transmission / reception engine 82 MPEG2 decoder 83 D / A conversion section 84 Second SS-CPU (communication state detecting means)

Claims (14)

Communication means for transmitting and receiving control commands including video and audio data, or communication channel change information,
Communication state detection means for detecting a communication state;
And a notifying unit for notifying at least the transmission state of the video and audio data based on the communication state detected by the communication state detecting unit.   2. The wireless communication apparatus according to claim 1, further comprising measuring a time when the communication is interrupted, and holding the communication channel until a predetermined time elapses after the communication is interrupted.   The wireless communication device according to claim 1, wherein the communication unit transmits the video and audio data or the control command by an SS wireless system.   4. The wireless communication apparatus according to claim 1, wherein the communication unit transmits the video and audio data using an MPEG stream conforming to an MPEG2 encoding scheme. 5.   The wireless communication device according to claim 1, wherein the communication unit is a low-power short-range two-way wireless communication.   The wireless communication device according to claim 1, wherein the communication unit is one of Bluetooth, UWB, and a wireless LAN.   The wireless communication device according to any one of claims 1 to 6, wherein the communication state detection means detects a communication state based on an electric field strength of a received radio wave, an error rate, or the number of retransmission requests based on the error rate. Communication device.   The wireless communication device according to claim 1, wherein the communication state detection unit detects a communication state between wireless communication devices with which a communication link has been established.   The notifying unit notifies at least one or more of the interruption of the video and audio data, the change of the communication channel, the connection, and the reception sensitivity information including out of the communication range. The wireless communication device according to claim 1, wherein:   The wireless communication device according to claim 1, wherein the notification unit is configured to display a message by a display unit or generate a message by a voice output unit. A wireless AV system for connecting a plurality of wireless communication devices through a wireless network,
The wireless AV system according to claim 1, wherein the wireless communication device is the wireless communication device according to claim 1.   The wireless communication device according to claim 11, wherein the wireless communication device is a television receiver including a display device, a center device having a tuner for broadcast reception, and transmitting video and audio data to the display device. Wireless AV system.   In a plurality of wireless communication devices constituting a wireless network, video and audio data, or send and receive a control command including communication channel change information, to detect the communication state, based on the detected communication state, at least the video and A program for causing a computer to execute a control process of notifying a transmission status of audio data.   In a plurality of wireless communication devices constituting a wireless network, video and audio data, or send and receive a control command including communication channel change information, to detect the communication state, based on the detected communication state, at least the video and A computer-readable recording medium having recorded thereon a program for causing a computer to execute a control process of notifying a transmission status of audio data.

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