JP4024776B2 - Wireless terminal, wireless system, wireless terminal control method, control program, and computer-readable recording medium recording the same - Google Patents

Description

The present invention relates to a wireless terminal, a wireless system, a wireless terminal control method, a control program, and a computer-readable recording medium recording the same.

  In recent years, with the explosive spread of the Internet, the number of cases in which a LAN (Local Area Network) is constructed in an office, a home, or the like is increasing. Thanks to the advancement of digital wireless communication technology, the need for so-called wireless LAN, which builds a wireless LAN due to the inconvenience of cabling, has increased greatly. In addition, the mobile environment represented by mobile terminals such as laptop computers It also helps us to use it below, and in the future, a considerable number of disseminated vehicles are expected. As a typical technology of this wireless LAN, there is IEEE 802.11 which has already been standardized by the Institute of Electrical and Electronics Engineers (IEEE). This standardized technology defines Ethernet from the physical layer to the MAC (Media Access Control) layer, which is the lower layer of the data link, in the OSI model, and is a wired LAN transmission path. (Registered trademark) can be replaced, and, as an additional function because it is wireless, a roaming function can be provided.

  In addition, preparations for new digital terrestrial broadcasts to replace analog terrestrial broadcasts currently being watched nationwide are in progress. This digital terrestrial broadcasting started in 2003 in the three major metropolitan areas of Kanto, Kinki and Tokai, and is planned to be expanded nationwide in 2006. Along with this, the current analog broadcasting will be abolished in 2011.

  ISDB (Integrated Services Digital Broadcasting) is a next-generation integrated digital broadcasting concept 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 transmission wave, a terrestrial broadcast wave, a coaxial cable, or a wired transmission line of an optical fiber is considered.

  In this terrestrial digital broadcasting technical standard ISDB-T (Terrestrial), OFDM (Orthogonal Frequency Division Multiplexing) that uses a large number of carriers as a modulation method is adopted, and multiple propagation paths (multipath) such as reflection by buildings are used. Ghost disturbance can also be suppressed. In ISDB-T, a transmission mode that defines the carrier interval, a modulation method for each carrier, and a plurality of guard intervals in the time axis direction that are provided for each effective symbol length are defined. Is allowed. Actually, an optimum format is selected from these according to services such as fixed reception and mobile reception.

  In ISDB-T, one transmission channel (communication channel) (bandwidth of about 5.6 MHz) is divided into 13 segments (1 segment = about 430 kHz), and the modulation system is changed in units of this. Accordingly, the broadcasting station can arbitrarily determine the signal configuration such as audio broadcasting and high-definition broadcasting, standard fixed broadcasting and mobile broadcasting using one transmission channel.

  Furthermore, since ISDB-T incorporates interleaving in the time axis direction and radio waves to be used are suitable for transmission to mobile objects, mobile receivers such as in-vehicle TVs, PDAs (Personal Digital Assistants) and mobile phones One of the major features is that stable reception is possible even with portable terminals such as the above. In the future, a service that assumes such mobile reception is also highly expected.

  By the way, in a wireless network, when a transmitter and a receiver communicate at a specific frequency (transmission channel), when another transmitter and receiver pair use the same transmission channel, the data transmission bandwidth is Therefore, it is necessary to automatically change the device that uses the transmission channel later to an empty transmission channel.

As a wireless communication device that changes 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, and two 2.4 GHz band and 5 GHz band signals are provided. By adapting to the frequency band, the wireless LAN system greatly increases the number of transmission channels that can be set simultaneously in the same area, and attempts to reduce the possibility that the communication link is interrupted by jamming radio waves.
JP 2002-33676 A (publication date: January 31, 2002) (FIG. 1)

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

  The present invention has been made to solve the above-described problems, and improves usability by preventing the user from feeling uncomfortable even when video display is interrupted due to a change in transmission channel or the like. An object of the present invention is to provide a wireless terminal, a base device, a wireless system, a wireless terminal control method, a wireless terminal control program, and a computer-readable recording medium recording the same.

The present invention also provides a wireless terminal, a wireless system, a wireless terminal control method, a control program, and a computer-readable recording medium on which the wireless terminal can maintain the optimal communication state as much as possible throughout the network. Objective.

  In order to solve the above-described problems, a wireless terminal according to the present invention includes a communication unit that transmits and receives control commands including video and / or audio data or transmission channel change information to and from a base device, and a communication state detection that detects a communication state. And a notification means for notifying at least the transmission status of the control command based on the communication state detected by the communication state detection means.

  The wireless terminal control method according to the present invention is a wireless terminal control method for configuring a wireless system in which a wireless terminal and a base device are connected through a wireless network, and includes video and / or audio data or a transmission channel. A control command including change information is transmitted / received to / from the base device, a communication state is detected, and at least a transmission state of the control command is notified based on the detected communication state.

  According to said structure, the transmission condition of the control command transmitted / received with a radio | wireless terminal and a base apparatus can be alert | reported. As this control command, for example, a “confirmation signal” transmitted to confirm the presence of a wireless terminal with which the base device is a communication partner, an “ACK signal” transmitted by the wireless terminal that has received the confirmation signal, or 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. Examples of notification messages include “out of service area” when radio waves stop reaching, “it is difficult to reach radio waves” when radio wave conditions are poor, and “transmitter” when searching for a transmitter to change the transmission channel to communicate. If you are searching for a transmitter to communicate with and you are setting up a connection, you may display "Connecting".

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

  Furthermore, the wireless terminal according to the present invention is characterized by comprising transmission channel holding means for measuring a time when communication is interrupted and holding the transmission channel until a predetermined time elapses after the communication is interrupted.

  According to the above configuration, it is possible to prevent frequent switching of transmission channels and maintain the optimum communication state as much as possible in the entire network.

  Further, in the wireless terminal according to the present invention, the communication state detection unit detects a communication state based on any one or more of the number of retransmission requests based on the electric field strength of the received radio wave, the error rate, and the error rate. It is characterized by being.

  According to the above wireless terminal, it is possible to suitably use the field strength of the received radio wave, the error rate, and the number of retransmission requests based on the error rate as parameters for detecting the communication state. In addition, a more effective communication state can be detected by combining a plurality of types of parameters.

  Furthermore, the wireless terminal according to the present invention is characterized in that the communication state detecting means detects a communication state with a base device with which a communication link is established.

  According to said structure, a communication state with the base apparatus with which the communication link was established is further detectable.

  Further, in the wireless terminal according to the present invention, the notification means includes reception that the video and / or audio data is interrupted, the transmission channel is being changed, the connection is being established, and the communication area is out of communication range. It is characterized by notifying one or more of the sensitivity information.

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

  Furthermore, the wireless terminal according to the present invention is characterized in that the notification means performs message display by a display means or message pronunciation by a voice output means.

  According to said structure, the information of the various contents which show a communication state can be appropriately shown to a user further by message display or message pronunciation.

  Further, when changing the transmission channel, the wireless terminal according to the present invention has a period longer than a period in which the base device makes a round of all the transmission channels, or all transmission channels in a period in which the wireless terminal holds one transmission channel. It is characterized in that the transmission channel is switched at any timing of a cycle for making a round.

  That is, the wireless terminal according to the present invention includes communication means for transmitting and receiving control commands including video and / or audio data or transmission channel change information to and from the base device, and communication state detection means for detecting a communication state, When changing the channel, the base device holds one transmission channel for a period longer than a period for making a round of all the transmission channels. Alternatively, a wireless terminal according to the present invention includes a communication unit that transmits and receives control commands including video and / or audio data or transmission channel change information to and from a base device, and a communication state detection unit that detects a communication state, and transmits When the channel is changed, the transmission channel is switched so that all the transmission channels go around during the period in which the base device holds one transmission channel.

  According to the above configuration, the wireless terminal and the base device can change the transmission channel at the same time, and the matching transmission channel can always be found, so the communication can be established by changing the transmission channel. Is possible.

  Furthermore, the wireless terminal according to the present invention is characterized in that the communication means transmits 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 apparatus.

  Furthermore, the wireless terminal according to the present invention is characterized in that the communication means performs low-power short-distance two-way wireless communication such as wireless LAN or Bluetooth and UWB (Ultra Wide Band).

  The wireless terminal is further suitable for a wireless communication apparatus that performs low-power short-distance bidirectional wireless communication such as a wireless LAN or Bluetooth and UWB (Ultra Wide Band).

  Furthermore, the wireless terminal according to the present invention is characterized in that the communication means transmits the video and / or audio data by an MPEG stream conforming to the MPEG2 encoding method.

  The wireless terminal is further suitable for a wireless communication apparatus that transmits the video and / or audio data using an MPEG stream compliant with the MPEG2 encoding method.

  Furthermore, the wireless terminal according to the present invention is characterized by including a display device that displays a video signal based on the received video data.

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

  Furthermore, the wireless terminal according to the present invention is characterized in that the communication state detecting means determines whether or not the video displayed on the display device is disturbed.

  According to said structure, it becomes possible to notify a user of a warning by detecting the case where the image | video displayed on a display apparatus is disturbed further.

  A wireless system according to the present invention includes the above-described wireless terminal and a base device that transmits and receives control commands including video and / or audio data or transmission channel change information to and from the wireless terminal.

  According to said structure, the transmission condition of the control command transmitted / received with a radio | wireless terminal and a base apparatus can be alert | reported. Therefore, according to the wireless terminal, it is possible to prevent the user from feeling uncomfortable even when the video display is interrupted due to a change in transmission channel or the like, and to improve the usability of the user.

  The wireless terminal may be realized by a computer. In this case, the computer can be read by recording a control program for the wireless terminal that causes the wireless terminal to be realized by the computer by operating the computer as each of the means. Various recording media are also within the scope of the present invention.

  As described above, the wireless terminal according to the present invention includes a communication unit that transmits / receives a control command including video and / or audio data or transmission channel change information to / from the base device, a communication state detection unit that detects a communication state, And a notifying means for notifying at least the transmission status of the control command based on the communication state detected by the communication state detecting means.

  Therefore, it is possible to prevent the user from feeling uncomfortable even when the video display is interrupted due to a change in the transmission channel or the like, and the user-friendliness can be improved.

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

  Therefore, it is possible to prevent frequent switching of transmission channels and maintain the optimum communication state as much as possible in 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. The wireless AV system 1 of the present embodiment is an example applied to a display-separated wireless TV receiver. FIG. 10 is an explanatory diagram showing an outline of the 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 referred to as a portable terminal (wireless terminal)). The wireless center 2 (wireless communication device, center device) and the TV body 3 (wireless communication device, display device) form a pair to form a wireless transmission network.

  As shown in FIG. 10, the TV body 3 is wireless with a built-in battery. A remote controller is also provided to allow remote control operations such as video decks. The wireless center 2 is connected to an antenna such as a BS or U / V, or an AV device such as a DVD player or a video deck. Then, video and / or audio data is wirelessly transmitted from the wireless center 2 to the TV body 3.

  As shown in FIG. 1, the wireless center 2 includes a BS 1 terminal, U / VHF antenna terminal 12 and diversity terminal 13, and a video 1 input terminal (S terminal) for connecting devices such as a digital VTR and a DVD player. 14), video 2 input terminal (decoder input) 15, video 3 input terminal (also used for monitor / BS output) 16, AC power supply unit 17, and Car-DC power supply unit 18.

  The TV body 3 includes a video 4 input terminal (also used as a 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 can be carried or carried by a built-in battery. The display device is a wide concept including the display device and is not limited by the display mechanism. In this specification, the TV main body 3 mainly has a display function, an acoustic function, and the like, while the wireless center 2 mainly stores a control function for controlling the tuner unit and the TV main body 3. 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 compliant with the IEEE 802.11 standard. Recently, the 5 GHz band is released as a frequency band, and a mode using the 5 GHz band instead of the 2.4 GHz band may be used. Data transmission from the wireless center 2 to the TV main body 3 uses moving picture expert group (MPEG) 2 video compression format to transmit moving image transmission, DVD-Video, and digital broadcasting over a communication line exceeding 10 Mbps. In addition, transmission of commands (control commands including transmission channel change information) between the wireless center 2 and the TV main body 3 is performed by the SS wireless method.

  When applying to an actual application including MPEG video and MPEG audio encoded streams (bit strings) and other encoded streams, the encoded streams are multiplexed and integrated into a single unit including synchronization. At the same time, it is necessary to make the stream a data format conforming to a specific physical format or protocol possessed by the storage medium or network.

  The MPEG2 system includes a program stream (MPEG2-PS, PS: Program Stream) that constitutes one program, and a transport stream (MPEG2-TS, TS: Transport Stream) that can constitute a plurality of programs, as in MPEG1. There is.

  The MPEG stream is a byte stream that is byte-aligned for each unit such as a header although there are many 1-bit flags. As a structure common to the entire MPEG system, the data portion that is not fixed length is preceded by information indicating the length. If unnecessary, that portion is skipped or the head of the next data group is confirmed and trusted. It has a data structure that enables highly-separated separation processing.

  An apparatus for receiving compressed video and audio signals in conformity with the MPEG2 encoding system is designed to receive video and audio sampling frequencies on the encoding side in order to prevent overflow and underflow of video and audio data on the decoding side. And the video, audio sampling frequency or STC (System Time Clock) on the decoding side must be matched.

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

  FIG. 2 is a block diagram showing the 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 channel selection signal, and a U / VHF broadcast is connected to a U / VHF antenna terminal 12 by a channel selection signal. A U / VHF tuner 32 that receives and selects, a video / audio demodulator 33 that demodulates 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 that switches between received audio and information related to a program such as an EPG (Electrical Program Guide), video / audio information received by a source selection signal, information related to a program, video 1 input terminal (external input) 1) 14, video 2 input terminal (decoder input) (external input 2) 15, video 3 input terminal (also used as monitor / BS output) (external input 3) The first selector 35 for selecting the external input information from 16 and the TV command signal 44 are transmitted and received, the data selected by the first selector 35 is converted into the MPEG2 video compression format, and the TV main body is converted by the SS wireless system. A wireless center for transmitting and receiving an SS transmission / reception unit 36 (communication means), a channel selection signal 41, a voice switching signal 42, a source selection signal 43, etc. An electrically rewritable nonvolatile memory that stores various data such as a microcomputer (hereinafter referred to as a microcomputer) 37 (transmission channel holding means), a control program for the wireless center microcomputer 37, communication control data, and a transmission channel change program. EEPROM (electrically erasable programmable ROM) as memory 38.

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

  The SS transmission / reception unit 36 includes an A / D conversion unit 51 that converts the data selected by the first selector 35 into a digital signal, an MPEG2 encoder 52 that converts the data into an MPEG2 video compression format, and transmission data according to the SS wireless system. The SS radio transmission / reception engine 53 including the SS radio device and the radio control unit for transmission, and each unit of the SS transmission / reception unit 36 are controlled, and the first SS-CPU 54 that detects the radio wave state is provided.

  The SS wireless transmission / reception engine 53 transmits / receives a command or the like to / from the SS transmission / reception unit 61 and a transmission function for transmitting an MPEG2 stream, a command, or the like to the SS transmission / reception unit 61 (described later in FIG. 3) of the TV body 3. With functionality.

  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, EPROM, EEPROM, and the time for program development / modification time is greatly reduced. . Further, if the program is downloaded and the program contents of the EEPROM are rewritten, it is possible to easily upgrade functions or change functions.

  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 / receives a TV command signal 71 to receive an MPEG2 stream and 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 into original data. (Restore) SS transmission / reception unit 61 (communication means), second data for selecting the data restored by the SS transmission / reception unit 61 and an AV signal input from the outside via the video 4 input terminal (also used for TV output) 21 The TV command signal 71 is transmitted to and received from the selector 62 and the TV section 63 (part of the notification means) that displays a video signal and outputs an audio signal. The source selection signal 72, OSD (on-screen TV microcomputer 64 (report) which transmits the display 73 etc. and controls the entire apparatus A part of the means, a transmission channel holding means), 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 a transmission channel change program, A remote control light receiving unit 66 that receives a control command from a remote control device (not shown) (hereinafter referred to as a remote control device), a battery 67, and a battery charger microcomputer 68 that controls charging / discharging of the battery 67 are configured.

  The SS transceiver unit 61 includes an SS radio transceiver engine 81 including an SS radio and a radio controller for receiving data transmitted by the SS radio system, an MPEG2 decoder 82 for decoding the received MPEG2 stream, and an analog signal for the decoded data. The D / A conversion unit 83 that converts the signal and the SS transmission / reception unit 61 are controlled, and the second SS-CPU 84 (communication state detection unit) that detects the radio wave state is provided.

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

  In particular, the second SS-CPU 84 detects a radio wave state detection for detecting a communication state (a radio wave strength, a communication path disturbance) between the wireless center 2 and the TV main body 3 by a retransmission request based on the electric field strength and error rate of the received radio wave. A function as a means is provided. 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 configuration in which the second SS-CPU 84 of the TV main body 3 has the above-described radio wave state detection function is shown. 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 may be used. Alternatively, both the first SS-CPU 54 and the second SS-CPU 84 may have a radio wave state detection function. Furthermore, the aspect which the TV microcomputer 64 or the wireless center microcomputer 37 performs the said electromagnetic wave state detection function may be sufficient.

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

  Further, the TV microcomputer 64 measures the time when the communication is interrupted, and performs transmission channel change control for holding the transmission channel until a predetermined set time elapses after the communication is interrupted. A specific example of 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 program channel, time, and volume on a screen of a television or the like. In an electronic device such as a video device such as a TV or a video conference system, information such as a program channel, time, and volume is generally displayed on a television screen. The OSD data is not an image, but is stored in a format called a bitmap. This bitmap is converted into YUV format pixel values represented by Y, Cb, and Cr, and the converted pixels are used for television broadcasting or the like. Is superimposed on the original image. If an image playback device such as a DVD (not shown) is connected to the video 4 input terminal (also used for TV output) 21, OSD display can be performed by superimposing the playback image on the display screen. Note that the OSD composition unit 69 (FIG. 4) performs image superimposition processing between an original image such as a television broadcast and the OSD display.

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

  Although not shown, the TV main unit 3 includes a speaker, a key input unit, a slot for inserting / removing a card type external expansion storage medium, and the like. It is good also as a structure which reads directly. Card-type external expansion storage media include, for example, an SRAM (Static RAM) card that holds information written by power backup, a flash memory that does not require power backup, etc., Compact Flash (CF) (registered trademark), smart media, memory It is a very small hard disk drive (HDD) or the like that can be mounted on a stick or a PC card Type II.

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

  The battery 67 supplies predetermined power to each part of the TV main body 3. When the battery 67 is in a chargeable state, the battery charger microcomputer 68 detects, for example, that the TV main body 3 is attached to the wireless center 2 or other cradle, and supplies a power supply terminal ( In either case, charging / discharging is controlled via a not shown). Specifically, the battery charger microcomputer 68 integrates the discharge current of the battery pack and starts charging when it is determined that the remaining capacity of the battery pack has become a predetermined value or less. The charging is stopped when it is determined that the battery pack has been fully charged. The charged battery 67 becomes the main power source of the portable TV when the TV main body 3 is disconnected from the commercial power source, and supplies 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 (3) transition from reception sensitivity deterioration, and FIG. 7 shows (4) transition from outside the 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 start-up When the power source of the TV main body 3 is turned on (S101), “connected” is displayed on the TV section 63 by the OSD output 73 (S102), and the system waits for start-up (S103). This “connected” display is displayed only when RC “on timer” and “off timer” are input. Also, the message “Clock is not set” is not displayed at startup.

  When the TV main unit 3 is activated, a control command from the remote control device is received to select a channel (S104). The channel selection operation will be described in detail. As shown in FIG. 3, the TV microcomputer 64 that has received a control command from the remote control device transmits a control command related to the channel selection to the SS transmission / reception unit 61 as a TV command transmission / reception 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 relating 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 channel selection signal 41 to the BS tuner 31 or the U / VHF tuner 32, and channel selection is performed by the corresponding tuners 31 and 32. As described above, between the wireless center 2 and the TV main body 3, data is basically sent from the wireless center 2 to the TV main body 3 as an MPEG2 stream by the SS wireless method, but the command transmission is performed between the wireless center 2 and the TV main body 3. The command data is transmitted and received. The above is an example of command transmission for channel selection, but similar command transmission is also performed for voice and source selection.

  Returning to the description of the transition at (1) start-up in FIG. 4, the TV microcomputer 64 detects the communication state (the strength of radio waves, the communication path) between the wireless center 2 and the TV main body 3 detected by the second SS-CPU 84. It is determined whether or not the reception sensitivity is good based on the interference information (S105). If the reception sensitivity is good, the mute is canceled (S106), “connected” is deleted (S107), and the state transitions to (2) normal viewing (reception sensitivity good) in FIG. 5 (S108). This mute is a non-video / silent process for eliminating video / audio noise when switching signal connection.

  As a result, “ON” is displayed on the TV section 63 by the OSD output 73 until the channel selection is completed after the power of the TV main unit 3 is turned on. It disappears and shifts to (2) normal viewing in FIG.

  If the reception sensitivity is not good in the determination in step S105, it is determined whether the reception sensitivity is deteriorated (S109). If the reception sensitivity has deteriorated, the mute is canceled (S110), and the TV section 63 displays "It is difficult to reach radio waves" by the OSD output 73 (S111), and (3) Reception sensitivity deterioration in FIG. (S112).

  If the reception sensitivity is not deteriorated in the determination of step S109, it is determined that the reception sensitivity is deteriorated (S113). If the reception sensitivity is deteriorated, the mute is not canceled and the TV section 63 is notified by the OSD output 73. “Out of service area” is displayed (S114), and the state transitions to (4) transition from outside service area in FIG. 7 (S115).

In this way, after the TV main unit 3 is turned on, “Connecting” is displayed. If the reception sensitivity is good, the “Connecting” display disappears. If the reception sensitivity is not good, “Connecting” is displayed. Is difficult to reach "or" out of service area "is displayed. Therefore, when the transmission channel is switched, the user can easily know whether the connection is being established, whether the reception state is bad and the video is interrupted, or whether the communication terminal has changed the transmission channel.
(2) Transition from normal viewing (good reception sensitivity) When in normal viewing state (S201), when the second SS-CPU 84 receives information on the communication state (the strength of radio waves, the disturbance of the communication path). Then, the deterioration of the reception sensitivity is determined (S202). If the reception sensitivity is deteriorated, the OSD output 73 displays “It is difficult to reach radio waves” on the TV section 63 (S203), and the transition to the transition state from (3) reception sensitivity deterioration in FIG. S204).

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

If the reception sensitivity is not improved in the determination in step S302, it is determined whether the reception sensitivity is deteriorated (S305). When reception sensitivity is deteriorated, muting is performed (S306), and the TVD 63 is switched to display "out of service area" from "It is difficult to reach radio waves" by the OSD output 73 (S307). 4) Transition to a transition state from outside the service area (S308). If the reception sensitivity has not deteriorated in the determination of step S305, it is determined whether or not a predetermined time (here, 10 seconds) has elapsed (S309). When 10 seconds have elapsed, the display of “It is difficult to receive radio waves” is deleted (S310). If it is not 10 seconds, it is determined whether or not the reception sensitivity deterioration state has elapsed for a predetermined time (here, 15 minutes) (S311). If 15 minutes have elapsed, it is determined that communication has been interrupted and the predetermined time has elapsed. Then, “the radio wave is difficult to reach” is displayed again on the TV section 63 by the OSD output 73 (S312). If it is determined in step S311 that 15 minutes have not elapsed, the process is not performed (S313).
(4) Transition from Out of Service Area When “out of service area” is present and the reception sensitivity is in a deteriorated state (S401), it is determined whether or not the reception sensitivity has been improved based on the communication state information from the second SS-CPU 84 (S402). ). If the reception sensitivity is improved, the display is switched from “It is difficult to receive radio waves” to “Connected” (S403), and the channel is selected (S404). The specific operation of channel selection has already been described. Next, the muting is canceled (S405), “in connection” is deleted (S406), and the state transitions to the transition state (2) normal viewing (good reception sensitivity) in FIG. 5 (S407).

  If the reception sensitivity is not improved or is deteriorated in the determination in step S402, the process is not performed (S408). At this time, the “out of service” display is continued.

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

  FIG. 8 is a diagram showing data transmission / reception of a plurality of transceivers A, B, and C, and FIG. 9 is a diagram for explaining an example of using transmission channels of the plurality of transceivers A, B, and C.

  8 and 9, the transmitter A is, for example, the above-described wireless center 2 of the liquid crystal TV, and the receiver A is the TV 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 mobile terminals thereof.

  As a technique for realizing a wireless AV system, for example, there is a standard specification called HAVi (Home Audio / Video Interoperability) Architecture that has been standardized in January 2000. As described in the HAVi V1.0 Specification version overview (1.1 General's 1.1 Scope), this specification connects home appliances and computers, and allows a user to use another device to connect another device. Provides an interface for operation. In the HAVi specification, as an example, it is assumed that a network is constructed by household appliances compliant with IEEE 1394 and IEC (International Electrotechnical Commission) 61883. Moreover, as in the same outline part of the specification, all users can freely use devices connected to the network realized by HAVi. In this way, by connecting AV devices in the home and constructing an AV network, the user can use any combination of devices in remote rooms.

  In addition to such a home AV network, the transceivers A, B, and C include, for example, a mobile phone / PHS (Personal Handy-Phone System) (registered trademark) or a personal digital assistant (hereinafter referred to as a PDA) that performs wireless communication. (Referred to as “Personal Digital Assistants”).

  On the other hand, a wireless LAN, Bluetooth, or UWB (Ultra Wide Band) is 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. In mobile phones that require lower power consumption, attention is paid to low-power short-distance two-way wireless communication systems such as Bluetooth and UWB. Bluetooth is a system that performs short-distance two-way wireless communication between a master (server) and a slave (client). 2.4 GHz can be used all over the world to enable 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 actual transmission channel rate can be synchronous voice communication up to three transmission channels, or voice and data can be communicated simultaneously on one transmission channel. Asynchronous channels support bi-directional connections at 721 Kbps and return direction connections at 57.6 Kbps, or symmetric links at 432.6 Kbps.

  FIG. 9 is a diagram for explaining a transmission channel changing method of the wireless AV system. When this wireless AV system conforms to the IEEE 802.11 standard, the frequencies of 14 transmission channels from the transmission channel ch1 to the transmission channel ch14 are allocated in the 2.4 GHz band of 2.400 to 2.483 GHz. However, when a plurality of transmission channels are set simultaneously in the same area, it is determined that the frequency interval between adjacent transmission channels is 25 MHz or more. This is because high-frequency signals to be transmitted and received have a certain modulated band, so that when the frequencies of adjacent transmission channels are close, the signals of the respective transmission channels interfere with each other with respect to the other party. Because it becomes. 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 as transmission channels A, B, and C (transmission channel C is not shown) as shown in FIG. If an attempt is made to construct a wireless LAN system for each house or room in an area where houses are densely populated or in a building where rooms are close as described above, a transmission channel shortage occurs.

  Therefore, in a wireless network, when a transmitter and receiver are communicating at a specific frequency (transmission channel), if another transmitter / receiver pair uses the same transmission channel, the transmission channel is used later. It is necessary to change the equipment to be used to an empty transmission channel.

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

  However, when viewed from the transmitter C, it may not be easy to determine whether 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 it without permission. When channel A begins to be used, if transmitter A communicates again, transmission channel A has been used by transmitter C, and transmitter A must go to find a new transmission channel. It may take about 3 seconds to switch the transmission channel because it includes processing such as initialization.

  Originally, the stream is interrupted while the transmission channel is changed. Therefore, in this embodiment, as described in detail with reference to FIGS. 4 to 7, when the communication state is interrupted, for example, when the transmission channel is switched, whether the video is interrupted or whether the transceiver changes the transmission channel. By notifying the user with messages such as “Connecting”, “Searching for transmission channel”, “Hard reception of radio waves”, “Out of range” (messages by display, messages by voice, or any combination thereof) It is possible to prevent the user from feeling uncomfortable.

  Furthermore, in this embodiment, the time when communication is interrupted in a certain transmission channel is measured, and when the time when communication is interrupted is within a predetermined set timeout time, control is performed to determine that the transmission channel is in use. . 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 when communication is interrupted and the process of determining that the communication is in use are performed by the control unit of the device that is to interrupt the transmission channel.

  In the example of FIG. 9, when the transmitter A is performing packet communication with the receiver A using the transmission channel A, the transmitter A is using the transmission channel A when the transmitter B tries to communicate. 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 tries to communicate further, the packet communication of the transmitter A and the packet communication of the transmitter B are interrupted, but both are within the set timeout period. 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, and an optimum communication state can be maintained in the entire network.

  Next, a method for detecting “out of service area” will be described with reference to FIGS. 11 to 15. This detection process 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. May be.

  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 existence of the other party. The ACK signal is a signal indicating that the confirmation signal has been received, and is transmitted when the confirmation signal is received. The confirmation signal may be a command signal. Since bidirectional communication is performed in this way, the reception side can also grasp the reception state by looking at the data state.

  In the example of FIG. 11, the ACK signal is transmitted for each confirmation signal. However, after the receiver receives the confirmation signal once, the ACK signal is periodically transmitted without receiving the confirmation signal. Alternatively, the confirmation signal may be omitted completely, and the ACK signal may be transmitted periodically without receiving the confirmation 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 is received while waiting for a certain time (S1203). If a confirmation signal is received (YES in S1203), an ACK signal is transmitted (S1204). On the other hand, when the confirmation signal is not received (NO in S1203), the count is increased 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 exceeds the predetermined value (YES in S1206), it is determined that the area is out of service (S1207).

  Here, the predetermined value is a value related to the processing time T for waiting for a predetermined time, and T seconds × the predetermined value is set to about 5 seconds. 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 in 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 a confirmation signal has been received while waiting for a predetermined time (S1303). If a confirmation signal is received (YES in S1303), an ACK signal is transmitted (S1304). On the other hand, if the confirmation signal is not 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 area is out of service (S1307).

  The processing procedure described above is processing on the side that receives the confirmation signal. Next, processing on the side that receives 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, when the ACK signal is not received (NO in S1404), the count is increased 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 predetermined time (S1402). On the other hand, if the count value exceeds the predetermined value (YES in S1406), it is determined that the area is out of service (S1407).

  FIG. 15 shows an example in which processing equivalent to that 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, when the ACK signal is not 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, if the difference value exceeds the predetermined value (YES in S1506), it is determined that the area is out of service (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 service when the ACK signal / confirmation signal does not return.

  Next, an example of a procedure for classifying the communication state into “good”, “deteriorated”, “deteriorated”, and “out of service area” based on an error rate or the like will be described using FIG. 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 the received packet. When the packet error rate is smaller than the threshold Th1 (YES in S1601), the communication state is determined as “good” (S1602). The threshold value Th1 can be set to about 0.001, for example. However, the present invention is not limited to this, and an optimum value can be selected according to the situation.

  Next, when 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 as “degraded” (S1604). Here, the threshold Th2 is preferably set to an upper limit value that does not disturb the video. In this case, “degradation” of the communication state indicates a state where the video is disturbed. The threshold Th2 can be set to about 3, for example. However, the present invention is not limited to this, and an optimum value can be selected according to the situation.

  Next, when the number of transmissions is greater than the threshold value Th2 (NO in S1603), it is determined whether or not it is out of service (S1605). The determination of out-of-service can be performed by the procedure shown in FIGS. 12 and 13 as described above. That is, a “confirmation signal” transmitted from the wireless center 2 to confirm the presence of the TV main body 3 that is a communication partner and an “ACK signal” transmitted from the TV main body 3 that has received the confirmation signal are transmitted for a predetermined time. It can be done by monitoring whether it can be received within. As a result of the determination, if it is not out of service area (NO in S1605), the communication state is determined as “deteriorated” (S1606). On the other hand, if it is out of range, the communication state is finally determined as “out of range” (S1607).

  In FIG. 16, the determination is made using the packet error rate and the number of retransmissions (S1601, S1603), but the communication state can be determined by using only the packet error rate and comparing it with a two-stage threshold. Good. Similarly, the communication state may be determined by using only the number of retransmissions and comparing it with a two-stage threshold. Needless to say, it is possible to make more detailed determinations by comparing with more threshold values without being limited to two stages. Therefore, for example, it is possible to combine two-stage determination using the packet error rate and two-stage determination using the number of retransmissions.

  In addition, the case where the radio wave reception state is detected by “error rate” and “number of retransmission requests based on error rate” has been described, but in addition, “field strength”, “temporal change in error rate”, “field strength “Time change”, “temporal change in number of retransmission requests”, and the like can be used as parameters. In particular, in the power saving mode for reducing power consumption, it is preferable to determine the radio wave state based on the electric field strength in a state where video and / or audio data is not transmitted / received.

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

  As shown in FIG. 17, in the transmitter (wireless center 2), first, transmission channel change determination is performed (S1701). The transmission channel change determination is made on the condition that the out-of-service state continues for a certain 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 of “transmission channel A”, “transmission channel B”, and “transmission channel C” as channels used in wireless transmission. The order of changing the transmission channel is assumed 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, this means that the transmission channel C is changed 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). When an ACK signal is received from the receiver (YES in S1704), the transmission channel is fixed and subsequent communication is performed. At this time, the communication state changes from “looking 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 changing the transmission channel is compared with the predetermined time TS (S1705). When the elapsed time is smaller than the predetermined time TS (NO in S1705), the process returns to the process of transmitting a confirmation signal (S1703). On the other hand, if the elapsed time is greater than the predetermined time TS (YES in S1705), the process returns to the process of changing the transmission channel (S1702).

  Next, processing in the receiver (TV main body 3) will be described in the same manner.

  First, 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 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 to that channel, an ACK signal is transmitted to the transmitter (S1714), and subsequent communication is performed. At this time, the communication state changes from “looking 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). If the elapsed time is less than the predetermined time TJ (NO in S1715), the process returns to the process of determining reception of 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 larger than the predetermined time TS of the transmitter, an opportunity to communicate on the same channel can be obtained even when the transmitter and the receiver perform processing for changing the transmission channel at the same time. For example, when the three transmission channels A, B, and C are changed in order, it is desirable that the predetermined time TJ> the predetermined time TS × 3.

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

  When the transmitter transmits a confirmation signal on transmission channels A and B, the receiver selects transmission channel C. Therefore, since the transmission channel is different, the confirmation signal does not reach the receiver. Thereafter, when the transmitter sends a confirmation signal on transmission channel C, the receiver still selects transmission channel C. Therefore, since the transmission channels match, the receiver receives the confirmation signal and transmits an ACK signal to the transmitter. As a result, communication is established between the transmitter and the receiver on the transmission channel C.

  Note that the wireless center 2 and the TV main body 3 of the wireless AV system 1 may perform communication state detection and notification based on video and / or audio data, or based on a control command including transmission channel change information. You may go. Whether it is video and / or audio data or a control command (ie, “confirmation signal”, “ACK signal”, etc. in FIG. 11), the same message is used to notify the transmission state. When the transmission state of any one of the video data, audio data, and control command is deteriorated, a notification message is displayed. Examples of notification messages include “out of service area” when radio waves stop reaching, “difficult to receive radio waves” when radio wave conditions are poor, and “sender "I am looking for", when a transmitter to communicate with is found and the connection is set, "Connecting" is displayed.

  Here, the transmission channel can be changed by a control command including “transmission channel change information” or by a 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 is changed. On the other hand, the latter corresponds to a case where the user setting is, for example, “AUTO (automatic)” and a search is made for an empty transmission channel.

  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 body 3 as a wireless terminal. The SS transmission / reception unit 61 that receives the MPEG2 stream and command transmission data transmitted from the unit 36 and decodes the received MPEG2 stream, the TV unit 63 that displays the video signal and outputs the audio signal, and the control of the entire apparatus And a second SS-CPU 84 for detecting a communication state between the wireless center 2 and the TV main body 3 based on a retransmission request based on the electric field strength of the received radio wave and the error rate. The video and audio data are interrupted based on the Each message of reception sensitivity information including that the channel is being changed, being connected, and out of communication range is OSD-displayed on the TV section 63, so when switching the transmission channel or when the communication state is interrupted due to poor radio wave condition Even so, an appropriate message that informs the transmission status will be displayed, and the user has poor communication due to whether the video has been interrupted or the communication terminal has changed the transmission channel, or due to jamming radio waves such as using a microwave oven. It is possible to easily know whether or not the user has become uncomfortable. For example, even if no video is displayed, a message such as “Connecting” is displayed by OSD display, so the user can intuitively understand why the video is not displayed and wait until the video is displayed. It is possible to prevent unnecessary transmission channel operation for avoiding a state in which no video is displayed. By avoiding unnecessary transmission channel operations by the user, the time until video display can be further shortened.

  In this embodiment, as described in (4) transition from outside the 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 in any step. For example, when deterioration or recovery of the communication state can be expected, it is easier to understand if an approximate time until video display is made or an image character indicating the time is notified.

  In addition, when the reception condition is getting worse, the next action guideline (for example, “Reception condition is getting worse. Please move to a place where radio waves are easy to reach.” Or “ It ’s worse. Please keep away from obstacles such as microwave ovens ”.

  In this embodiment, a message notifying the transmission status of video and audio data is displayed on the TV unit 63 by OSD, so that the message of the transmission status of video and audio data is notified. It may be used to notify by voice or in combination. In addition, any display method is not limited to OSD display.

  Furthermore, in this embodiment, the time when the communication is interrupted is measured, and the transmission channel is held until a predetermined set time elapses after the communication is interrupted, so that the transmission channel is frequently switched. And the optimum communication state can be maintained in the entire network.

  Note 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 modifications can be made without departing from the gist 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 a combination thereof. For example, as an AV device, in addition to a VTR (Video Tape Recorder), a recording / reproducing apparatus for recording on an HDD or a DVD may be used. In addition, as a device that can transmit and receive data, a device that is integrated with an information device function represented by a personal computer may be used, and it can be applied to all systems. The contents of the transmitted / received data may be anything.

  In this embodiment, the TV receiver has been described. However, the present invention is not limited to this, and as described above, the present invention can be applied to a tuner, a personal computer, and other AV devices using the tuner.

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

  In addition, as a tuner, two broadcasts of a BS tuner and a U / V tuner are given as an example, but the type and number of broadcasts such as a CS tuner are not limited to this.

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

  Further, in the present embodiment, the configuration in which the “notification unit” is provided on the reception side (TV main body 3) has been described, but the transmission side (wireless center 2) may be provided by a display panel, an LED, or the like. That is, the wireless AV system of the present invention only needs to have a configuration in which notification means for notifying the reception status on the reception side is provided on either the transmission side or the reception 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 can be read by inserting the recording medium therein. May be. In either case, the stored program may be configured to be accessed and executed by the CPU, or in any case, the program is read and the read program is not shown in a program storage area. The program may be downloaded and executed by the program. It is assumed that this download program is stored in the main device 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 medium carrying a fixed program including a disk system of an optical disk such as MD / DVD, a card system such as an IC card / optical card, or a semiconductor memory such as a mask ROM, EPROM, EEPROM, flash ROM or the like. .

  Furthermore, although not shown in the figure, when a means capable of connection to an external communication network is provided, the program is fluidly supported so that the program is downloaded from the communication network via the communication connection means. It may be a medium. When the program is downloaded from the communication network in this way, 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, and may be data.

  The present embodiment does not limit the scope of the present invention, and various modifications are possible within the scope of the present invention. For example, the present embodiment can be configured as follows.

  The wireless communication device of the present invention includes a communication unit that transmits and receives control commands including video and audio data or transmission channel change information, a communication state detection unit that detects a communication state, and a communication detected by the communication state detection unit. An informing means for informing at least the transmission status of the video and audio data based on the state may be provided.

  Furthermore, the time when the communication is interrupted may be measured, and the transmission channel may be held until a predetermined set 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-distance two-way wireless communication.

  As a more preferred specific mode, the communication means is Bluetooth, UWB, or wireless LAN.

  More preferably, the communication state detection means detects the communication state from 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 apparatuses with which communication links are established.

  In addition, the notifying means notifies at least one of the video and audio data being interrupted, the transmission channel being changed, being connected, and the reception sensitivity information including out of communication range. You may do.

  The notification unit may be a message display by a display unit or a message pronunciation by a voice output unit.

  The wireless AV system of the present invention is a wireless AV system in which a plurality of wireless communication devices are connected through a wireless network, and the wireless communication device may be the wireless communication device described above.

  As a more preferable specific aspect, the wireless communication device is a television receiver including a display device and a center device that has a broadcast receiving tuner and transmits video and audio data to the display device. .

  The operation control program of the present invention transmits and receives control commands including video and audio data or transmission channel change information in a plurality of wireless communication devices constituting a wireless network, detects a communication state, and detects the detected It may be a program for causing a computer to execute a control process for notifying at least the transmission status of the video and audio data based on the communication state.

  Furthermore, the recording medium on which the operation control program of the present invention is recorded is a plurality of wireless communication devices constituting a wireless network, which transmits and receives control commands including video and audio data or transmission channel change information, and detects a communication state. A program for causing a computer to execute a control process for notifying at least the transmission status of the video and audio data based on the detected communication state may be recorded.

  In addition, the wireless terminal of the present invention includes a communication unit that transmits / receives a control command including video and / or audio data or transmission channel change information to / from a base device, a communication state detection unit that detects a communication state, and the communication state detection Informing means for informing reception sensitivity information based on the communication state detected by the means may be provided.

  In addition, the wireless terminal of the present invention includes a communication unit that transmits / receives a control command including video and / or audio data or transmission channel change information to / from a base device, a communication state detection unit that detects a communication state, and the communication state detection And at least notification means for notifying the transmission status of the video and / or audio data based on the communication state detected by the means.

  Furthermore, 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 elapses after the communication is interrupted.

  Furthermore, in the wireless terminal of the present invention, the communication state detection means detects a communication state based on one or more of the field strength of the received radio wave, the error rate, and the number of retransmission requests based on the error rate. May be.

  Furthermore, in the wireless terminal according to the present invention, the communication state detection unit may detect a communication state with a base device with which a communication link is established.

  Furthermore, in the wireless terminal of the present invention, the notification means includes a reception sensitivity including that the video and / or audio data is interrupted, the transmission channel is being changed, the connection is being established, and the communication area is out of the communication range. Any one or more of the information may be notified.

  The wireless terminal of the present invention further includes a communication unit that transmits and receives a control command including video and / or audio data or transmission channel change information to and from the base device, and the communication unit is detected by the base device. Information indicating a communication state is received from a base device, and a notification unit that notifies reception sensitivity information based on the information indicating the communication state received by the communication unit may be provided.

  Further, in the wireless terminal of the present invention, the notification 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 and receiving control commands including video and / or audio data or transmission channel change information to and from the base device, measures the time when the communication is interrupted, and the communication is interrupted. Transmission channel holding means for holding the transmission channel may be provided until a predetermined time elapses.

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

  Furthermore, in the wireless terminal of the present invention, the communication means may perform wireless LAN or low-power short-distance bidirectional wireless communication such as Bluetooth and UWB (Ultra Wide Band).

  Furthermore, in the wireless terminal of the present invention, the communication means may transmit the video and / or audio data using an MPEG stream conforming to the MPEG2 encoding method.

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

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

  Furthermore, the base device of 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.

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

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

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

  Also, the wireless terminal control method of the present invention is a wireless terminal control method that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network, and changes 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 used.

  Also, the wireless terminal control method of the present invention is a wireless terminal control method that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network, and changes video and / or audio data or a transmission channel. A method of transmitting / receiving a control command including information to / 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 used.

  Also, the wireless terminal control method of the present invention is a wireless terminal control method that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network, and changes video and / or audio data or a transmission channel. A control command including information is transmitted to and received 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 notified based on the information indicating the communication state. It may be a method.

  Also, the wireless terminal control method of the present invention is a wireless terminal control method that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network, and changes 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, a time when communication is interrupted is measured, and a transmission channel is held until a predetermined time elapses after the communication is interrupted.

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

  The computer-readable recording medium of the present invention is a recording medium for recording the above-described wireless terminal control program.

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

It is a block diagram which shows the structure of the wireless AV system of embodiment of this invention. It is a block diagram which shows the structure of the wireless center of the wireless AV system shown in FIG. It is a block diagram which shows the structure of TV main body of the wireless AV system shown in FIG. It is a state transition diagram for demonstrating the transmission channel change method in the wireless AV system shown in FIG. It is a state transition diagram for demonstrating the transmission channel change method in the wireless AV system shown in FIG. It is a state transition diagram for demonstrating the transmission channel change method in the wireless AV system shown in FIG. It is a state transition diagram for demonstrating the transmission channel change method in the wireless AV system shown in FIG. It is a figure which shows transmission / reception of the data of several transmitter / receiver A, B, C of the wireless AV system shown in FIG. It is a figure explaining the usage example of the transmission channel of several transmitter / receiver A, B, C of the wireless AV system shown in FIG. It is explanatory drawing which showed the outline of the wireless AV system shown in FIG. It is explanatory drawing which shows the control command transmitted / received between the wireless center of the wireless AV system shown in FIG. 1, and TV main body. 2 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 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 wireless center of the wireless AV system shown in FIG. 1. 3 is a flowchart showing a process of determining “out of service” in the wireless center of the wireless AV system shown in FIG. 1. 3 is a flowchart showing a communication state determination process in the TV main body of the wireless AV system shown in FIG. 1. 2 is a flowchart showing transmission channel change processing in the wireless center and TV main body of the wireless AV system shown in FIG. 1. It is explanatory drawing which shows an example of the transmission channel change by the wireless center and TV main body of the wireless AV system shown in FIG.

Explanation of symbols

1 Wireless AV system 2 Wireless center unit (wireless center) (base equipment, wireless communication device, center device)
3 Television body unit (TV body) (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 monitor / BS output)
17 AC power supply unit 18 Car-DC power supply unit 21 Video 4 input terminal (also used for 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 detection means)
61 SS transceiver unit (communication means)
62 Second selector 63 TV section (part of notification means)
64 TV microcomputer (part of notification means, transmission channel holding means)
66 Remote control light receiving unit 67 Battery 68 Battery charger microcomputer 81 SS wireless transmission / reception engine 82 MPEG2 decoder 83 D / A conversion unit 84 Second SS-CPU (communication state detection means)

Claims (20)

Communication means for transmitting and receiving control commands including video and / or audio data or transmission channel change information to and from the base device;
Communication state detecting means for detecting a communication state ;
Informing means for informing at least the transmission status of the control command based on the communication state detected by the communication state detecting means;
Display means for displaying an image based on the received video data;
When changing the transmission channel, the base device holds one transmission channel for a period longer than the period in which all the transmission channels go around ,
The wireless terminal , wherein the notification unit displays the message display by the display unit superimposed on an image based on the received video data .   Communication means for transmitting and receiving control commands including video and / or audio data or transmission channel change information to and from the base device;
  Communication state detecting means for detecting a communication state;
  Informing means for informing at least the transmission status of the control command based on the communication state detected by the communication state detecting means;
  Display means for displaying an image based on the received video data;
  When changing the transmission channel, the base device switches the transmission channel so that all the transmission channels go around during the period of holding one transmission channel,
  The wireless terminal, wherein the notification unit displays the message display by the display unit superimposed on an image based on the received video data.   The wireless terminal according to claim 1, further comprising: a transmission channel holding unit that measures a time when communication is interrupted and holds a transmission channel until a predetermined time elapses after the communication is interrupted.   The communication state detecting means detects a communication state based on any one or more of the field strength of received radio waves, an error rate, and the number of retransmission requests based on the error rate. 4. The wireless terminal according to claim 1.   The wireless terminal according to any one of claims 1 to 4, wherein the communication state detection means detects a communication state with a base device with which a communication link has been established.   The notification means is any one or more of reception sensitivity information including that the video and / or audio data is interrupted, the transmission channel is being changed, the connection is being made, and the communication area is out of service area. The wireless terminal according to claim 1, wherein the wireless terminal is notified.   The wireless terminal according to claim 1 or 2, wherein the notification means performs message display by a display means or message generation by a voice output means.   The wireless terminal according to any one of claims 1 to 7, wherein the communication unit transmits the video and / or audio data or the control command by a spread spectrum wireless system.   9. The device according to claim 1, wherein the communication unit performs low-power short-distance bidirectional wireless communication such as wireless LAN or Bluetooth and UWB (Ultra Wide Band). Wireless terminal.   The wireless terminal according to any one of claims 1 to 9, wherein the communication means transmits the video and / or audio data by an MPEG stream conforming to an MPEG2 encoding system.   The wireless terminal according to claim 1, further comprising a display device that displays a video signal based on the received video data.   The wireless terminal according to any one of claims 1 to 11, wherein the communication state detection unit determines whether or not an image displayed on a display device is disturbed.   A wireless terminal according to claim 1;
  A wireless system, comprising: a base device that transmits and receives control commands including video and / or audio data or transmission channel change information to and from the wireless terminal.   A wireless terminal according to claim 3;
  A wireless system, comprising: a base device that transmits and receives control commands including video and / or audio data or transmission channel change information to and from the wireless terminal.   The base device is
  Comprising communication state detecting means for detecting a communication state;
  The wireless system according to claim 13 or 14, wherein information indicating a communication state detected by the communication state detection unit is transmitted to the wireless terminal.   16. The wireless system according to claim 13, wherein the video and / or audio data input to the base device is data from a broadcast receiving tuner.   A method of controlling a wireless terminal that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network,
  Processing for transmitting and receiving control commands including video and / or audio data or transmission channel change information to and from the base device;
  Processing to detect the communication state;
  Based on the detected communication state, a process for notifying at least the transmission status of the control command;
  When changing the transmission channel, the base device holds one transmission channel for a period longer than the period in which all the transmission channels go around;
  A method of controlling a wireless terminal, comprising: a process of superimposing and displaying a message display on an image based on received video data at the time of the notification.   A method of controlling a wireless terminal that constitutes a wireless system in which a wireless terminal and a base device are connected through a wireless network,
  Processing for transmitting and receiving control commands including video and / or audio data or transmission channel change information to and from the base device;
  Processing to detect the communication state;
  Based on the detected communication state, a process for notifying at least the transmission status of the control command;
  When changing the transmission channel, a process of switching the transmission channel so that all the transmission channels go around during the period in which the base device holds one transmission channel;
  A method of controlling a wireless terminal, comprising: a process of superimposing and displaying a message display on an image based on received video data at the time of the notification.   A control program for operating the wireless terminal according to claim 1 or 2 for causing a computer to function as the wireless terminal.   A computer-readable recording medium on which the control program according to claim 19 is recorded.

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