JP2007134896A - Mobile terminal device and information transmitting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To easily reproduce a video signal or audio signal of a mobile terminal device as a large picture or with high sound quality respectively by applying existent equipment. <P>SOLUTION: The mobile terminal device 100 has at least a display unit 207 which displays video, an audio output unit 204 which outputs audio, and an antenna 304 which transmits a television broadcast wave, and is equipped with a television broadcast wave transmitting means 301 of outputting the video signal and/or audio signal from the antenna 304 to external equipment by using a radio wave of a specified channel of a television broadcast frequency band. This television broadcast wave transmitting means 301 comprises a video signal conversion unit which converts a digital video signal into an analog video signal and a television broadcast wave output unit which modulates the analog video signal converted by the video signal conversion unit and the audio signal so that they can be transmitted as a television broadcast wave, and outputs them to the antenna 304. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a portable terminal device and an information transmission method, and more particularly to a portable terminal device that transmits a video signal and / or an audio signal to an external device and displays or reproduces the signal on the external device and an information transmission method thereof.

  Conventionally, when the image displayed on the display screen of the mobile phone is output to the outside, the digital video signal of the image displayed on the display screen of the mobile phone is converted into an analog NTSC (National Television Standards Committee) video signal. In general, a method of connecting the mobile phone and an external display device with a dedicated cable is common. There are various adverse effects of using this dedicated cable. An example is given below.

-The location where the mobile phone is used is limited by the length of the dedicated cable.
-Only a display device with an AV (Audio-Visual) input terminal for inserting a dedicated cable can be used.
・ With the increase in household appliances in the home, a wide variety of cables are overflowing in the home, and the cable you want to use cannot be found immediately when you want to use it.
・ Purchase of dedicated cables generally requires several hundred yen.
-Since a terminal for inserting the connector of the dedicated cable is also required on the mobile phone side, a space for arranging the terminal on the mobile phone side is prepared, and as a result, the mobile phone becomes large.

On the other hand, as a method that does not use a dedicated cable, a mobile communication terminal such as a mobile phone has a large screen size using various communication information received via a wireless communication line using a nearby communication means such as Bluetooth (registered trademark). A system for transmitting to a display device and solving the problem of the screen size of a mobile communication terminal has been proposed (for example, see Patent Document 1).
JP 2002-101457 A

  By the way, the system described in Patent Document 1 is applied to an existing display device that requires a Bluetooth receiver on the display device side and does not have a Bluetooth receiver when, for example, Bluetooth is used as the proximity communication means. I couldn't. Or, it was necessary to construct a new Bluetooth receiver on the display device side, which was a heavy burden on consumers.

  Further, as a problem along with the screen size of a mobile terminal device such as a mobile phone, generally, the performance of a speaker mounted on the mobile terminal device is not high, and viewing with satisfactory sound quality cannot be performed.

  The present invention has been made in view of such a point, and it is intended to make it possible to easily reproduce a video signal or an audio signal of a mobile terminal device with a large screen or high sound quality by using an existing device. Objective.

In order to solve the above problems, the present invention provides a mobile terminal device including at least a display unit that displays video, an audio output unit that emits audio, and an antenna that transmits a television broadcast wave. And / or a television broadcast wave transmitting means for outputting an audio signal from an antenna to an external device using radio waves of a predetermined channel in the television broadcast frequency band.
As one aspect of the mobile terminal device described above, the television broadcast wave transmitting means converts a digital video signal into an analog video signal, and an analog video converted by the video signal conversion unit. A television broadcast wave output unit that modulates the signal and the audio signal so as to be transmitted as a television broadcast wave and outputs the modulated signal to the antenna is configured.

According to the above configuration, a video signal and / or an audio signal are transmitted on a television broadcast wave from a mobile terminal device to an external device, and the display function of the external device is used without modifying the external device on the receiving side. The video signal can be displayed on a larger screen, or the audio signal can be reproduced in a higher sound quality environment by using the audio output function.
Further, according to one aspect of the mobile terminal device, when the television reception function mounted on the external device is capable of receiving only an analog signal television broadcast wave, the television broadcast wave transmitting means of the mobile terminal device Is composed of the video signal conversion unit and the television broadcast wave output unit, so that even an external device having only an analog television broadcast wave reception function can transmit a video signal and / or an audio signal to a television broadcast. It can be transmitted from a portable terminal device to an external device on a wave.

  According to the present invention, in the configuration described above, an empty channel survey unit that investigates an empty channel in a television broadcast frequency band, and a control unit that performs channel setting of the external device based on an empty channel detected by the empty channel survey unit And an infrared communication unit that performs infrared communication with an external device. The control unit receives a transmission command from the outside, and transmits a video signal to the external device using an empty channel by the television broadcast wave transmission unit. In addition, the channel setting information is transmitted to the external device via the infrared communication unit, and the video signal transmitted to the external device is displayed on the display screen of the external device using the channel based on the channel setting information. And

  According to the above configuration, the video signal is transmitted from the portable terminal device to the external device using the empty channel, and at the same time, the empty channel information is transmitted to the external device using infrared communication. As a result, the video signal is sent to the external device and the channel is set at the same time, and the user can automatically display the video signal using the empty channel without adjusting the channel of the external device.

  Further, according to the present invention, in the configuration described above, the control unit further sets a volume when the audio signal transmitted from the external device is reproduced according to a predetermined condition, receives the transmission command, and receives the infrared communication. Volume setting information is transmitted to an external device via a unit, and the audio signal transmitted to the external device is reproduced at a volume based on the volume setting information.

  According to the above configuration, the audio signal is transmitted from the portable terminal device to the external device, and at the same time, the volume setting information of the external device is transmitted to the external device using infrared communication, so that the audio signal is transmitted and simultaneously reproduced. Therefore, the user can reproduce the audio signal with an appropriate volume without adjusting the volume of the external device.

  Further, the present invention is a portable terminal device including at least an audio output unit that emits sound, an antenna that transmits radio broadcast waves, and an empty channel survey unit that investigates an empty channel of a radio broadcast frequency band, The control unit that instructs to use the empty channel detected by the empty channel survey unit when transmitting the audio signal, and the radio broadcast wave output that outputs the audio signal to the antenna using the empty channel according to the instruction of the control unit It comprises a part.

  According to the above configuration, the audio signal is transmitted on the radio broadcast wave from the mobile terminal device to the external device, and the audio signal is transmitted using the radio broadcast reception function of the external device without modifying the external device on the receiving side. Play in a high-quality environment.

  According to the present invention, the video signal or audio signal of the mobile terminal device can be transmitted to each existing device. Then, the video signal can be easily displayed on a large screen or the audio signal can be reproduced with high sound quality by using the display function and the audio output function of the device.

  Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a diagram schematically showing the concept of the present invention. In FIG. 1, the human face image 102 is currently displayed on the display unit 207 of the mobile terminal device 100. The mobile terminal device 100 can be applied to, for example, a mobile phone (also called “mobile communication terminal” or the like). The video (information) 102 displayed on the display unit 207 of the mobile terminal device 100 is converted into an NTSC video signal, for example, and transmitted to the television receiver 110 for general homes using the radio wave 103. The On the screen 111 of the television receiver 110, the same video (information) 102a as the video (information) 102 displayed on the display unit 207 of the mobile terminal device 100 is displayed on a large screen.

  The radio wave 103 uses a frequency band of a television broadcast wave. As will be described later, the NTSC video signal is AM (Amplitude Modulation) modulated, and the audio signal is FM (Frequency Modulation) modulated. The radio wave 103 is skipped to an empty channel for television broadcasting. The vacant channel of this television broadcast is a television that is not occupied by any broadcasting station in the region of the VHF band (1ch to 12ch) or UHF band (13ch to 62ch) of the current television broadcasting frequency band. It refers to the broadcast frequency.

  The portable terminal device 100 may be any portable terminal device that has a television broadcast wave transmission function and includes a display unit. In addition, although NTSC was mentioned as an example as a television broadcasting system, it is applicable also to other systems, such as PAL (Phase Alternation by Line).

  As described above, this system enables a small screen of the mobile terminal device 100 to be displayed wirelessly on the television receiver 110 in a general home. In order to transmit video and music information on a television broadcast radio wave from the mobile terminal device 100 side, the video displayed on the display unit 207 of the mobile terminal device 100 is displayed on the existing television receiver 110, and music is displayed. The receiver (television receiver 110) need not be modified.

  FIG. 2 shows a block configuration example in the mobile terminal device 100. The mobile terminal device 100 includes an antenna 201 connected to the communication circuit 202, and transmits and receives radio waves to and from a base station (not shown) of the mobile phone network through the antenna 201 under the control of the control unit 210. The communication circuit 202 modulates and demodulates radio waves exchanged with the base station. When performing communication for a call through the communication circuit 202, the audio data received from the base station is converted from an electrical signal to audio by the speaker (audio output unit) 204 and output, and the microphone (sound collecting unit) 203 outputs it. Audio data obtained by converting the picked-up audio into an electrical signal is supplied to the communication circuit 202 and transmitted to the base station.

  The mobile terminal device 100 includes an operation unit 206 configured with a jog dial, a keypad, and the like, and a display unit 207 configured with a liquid crystal display (LCD). The operation unit 206 can perform input operations such as telephone numbers and e-mail texts, and various mode setting operations.

  The control unit 220 includes an arithmetic control device (processor) such as a CPU (Central Processing Unit), for example, and uses a RAM (Random Access Memory) (not shown) as a work area for various processes, and a ROM (Read Only Memory) (not shown). A predetermined process is executed in accordance with the computer program recorded in (1).

  In this embodiment, the control unit 220 investigates (searches) an empty channel in the television broadcast frequency band, and uses the infrared rays output from the infrared communication unit to connect the mobile terminal device and the external device. It also functions as a distance measuring unit that measures the distance. Furthermore, it has an automatic volume control function for determining an appropriate volume of the television receiver 110 according to the result of distance measurement.

  The memory 205 includes a non-volatile memory such as a flash memory, and stores various information such as a phone book, schedule, mail message, image, music, application software, bookmark, and web page. A part of the computer program recorded in the ROM described above may be stored in the memory 205.

  The infrared communication unit 209 performs infrared communication (so-called “infrared remote control communication”) between the mobile terminal device 100 and an external device including the infrared reception unit, in this example, the television receiver 110. It is used to operate the television receiver 110 from a remote place (remote control operation). Various command signals input by the user operating the operation unit 206 are superimposed on the infrared rays output from the infrared communication unit 209 and transmitted to the television receiver 110 in accordance with standards such as IrDA (Infrared Data Association). Is done. The television receiver 110 receives this infrared signal and performs various operations based on the command signal included in the infrared signal.

  The timer unit 210 generates a pulse periodically by a circuit having a crystal oscillator, for example, and the control unit 220 can detect the current time by measuring the pulse. The timer unit 210 can be substituted by the internal clock of the controller 220.

  Television broadcast wave transmission means (hereinafter referred to as “TV transmission unit”) 301 takes out video information displayed on display unit 207 through data line 260, converts it into an NTSC video signal, and receives television broadcast. And input to the antenna 304 for transmission. Further, the audio information input to the speaker 204 is also supplied to the television broadcast wave transmitting means 301 and input to the antenna 304 after performing a predetermined modulation process. That is, the digital video signal of the video displayed on the display unit 207 and the audio signal emitted from the speaker 204 are converted into a television broadcast wave radio wave 103 by the television broadcast wave transmitting means 301 through the antenna 304 and the television. It is transmitted to most devices such as the receiver 110.

  The antenna 304 has a transmission / reception / reception switching function, and does not affect a reception system including a television broadcast control unit (hereinafter referred to as “TV control unit”) 208 as a component when transmitting a television broadcast signal. It is considered so.

  The control line 250 is a line (signal line) for flowing a signal for controlling each device connected to the control line 250. Some devices in the mobile terminal device 100 are connected to the control unit 220 through the control line 250, and processing in each device is performed under the control of the control unit 220. The data line 260 is a line (signal line) for transferring data between devices connected thereto.

  FIG. 3 is a configuration diagram of a TV transmission unit in the mobile terminal device 100 of this example. As shown in FIG. 3, the TV transmission unit 301 includes a digital / NTSC conversion circuit 302 and a TV transmission circuit 303. Here, the flow until the digital video signal and the audio signal are transmitted as a television broadcast wave in the TV transmission unit 301 will be described in detail.

  The digital / NTSC conversion circuit 302 functions as a video signal conversion unit that converts a digital video signal into an analog video signal. In this example, the digital video signal 306 of the video displayed on the display unit 207 is converted into an NTSC video signal 307.

  The TV transmission circuit 303 to which the NTSC video signal 307 is input performs a predetermined modulation process so that the NTSC video signal 307 can be transmitted as a television broadcast wave, and serves as a television broadcast wave output unit that outputs the modulated signal to the antenna. It functions. In addition to the video signal, an audio signal 305 is also input to the TV transmission circuit 303. The TV transmission circuit 303 performs AM (Amplitude Modulation) modulation on the NTSC video signal 307 and FM (Frequency Modulation) modulation on the audio signal 305.

  Furthermore, the video / audio decoded signal 308 adapted to the television broadcast wave is generated by multiplexing the modulated video signal and audio signal. For example, the subcarrier audio signal is multiplexed at a frequency of 4.5 MHz away from the main carrier video signal. Then, the generated video / audio decoded signal 308 is output to the antenna 304 for transmitting / receiving television broadcast waves.

  The TV transmission unit 301 (TV transmission circuit 303) can cover not only one frequency but also a wide frequency band from VHF to UHF. As an example, the antenna 304 may be a shortened monopole antenna, and may be externally attached to the mobile terminal device 100, or may have a shape embedded in the mobile terminal device 100 or embedded in an exterior portion.

  When the television broadcast receiving function mounted on the television receiver 110 is capable of receiving only analog television broadcast waves, the TV transmission unit 301 of the portable terminal device 100 is connected to the digital / NTSC conversion circuit 302. By configuring the TV transmission circuit 303, even a device having only an analog television broadcast reception function, a video signal and / or an audio signal can be carried on a television broadcast wave from the portable terminal device 100 to the television receiver. 110 can be transmitted. If the television receiver 110 can receive a digital video signal, the digital / NTSC conversion circuit 302 is not necessary.

  In the case of the portable terminal device 100 equipped with the NTSC video signal output function (digital / NTSC conversion circuit 302), this system can be configured by connecting the TV transmission circuit 303 shown in FIG.

  Next, various setting processes performed by the mobile terminal device 100 according to the present embodiment will be described with reference to FIG. 5 is a flowchart showing various setting processes by the mobile terminal device 100 of the present example. The mobile terminal device 100 is roughly divided into an empty channel automatic search (transmission to an empty channel), an automatic channel selection on the television receiver 110 side by an infrared remote control function, and an automatic volume control function.

  In FIG. 4, first, the following processing is started from a state in which an image is displayed on the display unit 207 of the mobile terminal device 100. In a state where video is displayed on the display unit 207 of the mobile terminal device 100, the control unit 220 sets a key on a menu screen (not shown) for the user to operate the operation unit 206 to transmit a video signal. Alternatively, it is determined whether or not a predetermined button has been pressed (step S1). Monitoring continues until a pressing of a set key or button is detected.

  When it is detected in step S1 that the setting key or button has been pressed, an empty channel survey unit (control unit 220) automatically searches for an empty channel in the television broadcast frequency band. When an empty channel is detected, the control unit 220 determines this empty channel as a use channel (step S2).

  In order to send information to the television broadcasting frequency band using radio waves, it is necessary to avoid frequencies already used by other broadcasting stations. Therefore, a frequency corresponding to an empty channel is automatically searched, and information is transmitted using the empty channel detected by this search.

  After finishing the process of step S2, transmission of the video / audio decoded signal 308 to the television broadcast wave is started (step S3). The vacant channel detected by the vacant channel automatic search can be transmitted to the television receiver 110, and the television receiver 110 can be operated automatically. This function is realized by the infrared communication unit 209 mounted on the mobile terminal device 100.

  The control unit 220 starts the transmission of the video / audio decoded signal 308 to the television receiver 110 by using the empty channel of the television broadcast frequency band by the television broadcast wave transmission means (TV transmission unit 301).

  At the same time, the infrared remote controller is activated to set the channel of the television receiver 110 (step S4). That is, channel setting information (empty channel information) is transmitted to the television receiver 110 via the infrared communication unit 209.

  Here, infrared automatic ranging is performed, an appropriate volume of the television receiver 110 is set on the basis of the measurement result, and volume setting information is transmitted to the television receiver 110 by infrared communication. Adjustment is performed (step S5), and a series of setting processing of the mobile terminal device 100 is completed.

  Infrared automatic ranging is to measure the distance between the mobile terminal device 100 and the television receiver 110 using infrared rays output from the infrared communication unit 209. The volume of the television receiver 110 is appropriately set according to the distance obtained by this measurement. The distance measurement method using infrared rays can measure the distance by, for example, emitting infrared rays to a measurement object and monitoring the angle change of the reflected infrared rays or detecting time.

  In addition to infrared automatic ranging, as an example that may be a condition for automatic volume adjustment, the control unit 220 receives time information of the time measuring unit 210 and measures the current time, and uses that time, for example, one day Adjust the volume at morning, noon, and night. Alternatively, the control unit 220 may determine a situation such as a quiet room or a noisy room depending on the volume of sound collected from the microphone 203, and adjust the volume according to the situation.

  As described above, the mobile terminal device 100 performs an automatic channel search, determines an empty channel, and sends information to the frequency of the empty channel. At the same time, the infrared remote control function is also activated, and “TV receiver 110 is turned on” → “TV broadcast channel setting (automatically searched empty channel)” → “volume automatic setting” is automatically performed.

  For example, when a videophone call is made, the button is displayed on the display unit 207 of the mobile terminal device 100 by simply pressing one button on the operation unit 206 of the mobile terminal device 100 (without touching the television receiver 110). The displayed video can be displayed on the display screen 111 of the television receiver 100.

  According to the configuration described above, video signals and / or audio signals are transmitted on the television broadcast wave from the mobile terminal device 100 to the television receiver 110, and the television receiver 110 on the receiving side is not modified. The video signal can be displayed on a larger screen 111 using the display function of the television receiver 110, and the audio signal can be reproduced in a higher sound quality environment using the audio output function.

  In addition, a video signal is transmitted from the portable terminal device 100 to the television receiver 110 using a vacant channel, and at the same time, vacant channel information is transmitted to the television receiver 110 using infrared communication. As a result, the use channel is set simultaneously with sending the video signal to the television receiver 110, and the user can automatically display the video signal using the empty channel without adjusting the channel of the television broadcast. it can.

  Further, at the same time as transmitting an audio signal from the portable terminal device 100 to the television receiver 110, and transmitting the volume setting information of the television receiver 110 using infrared communication, the audio signal is transmitted and simultaneously reproduced. Therefore, the user can reproduce the audio signal with an appropriate volume without adjusting the volume of the television receiver 110.

  As a specific effect of the above-described embodiment, since a general household television receiver 110 is used, no special modification is required for the reception facility.

  Even a very old generation television receiver can transmit video signals and audio signals to and from a portable terminal device to which the present invention is applied.

  Further, since the screen image of the portable terminal device 100 can be displayed on the large screen 111 of the television receiver 111, the portable terminal device 100 can be easily used even by a person with weak vision such as the elderly.

  Further, by displaying the video of the mobile terminal device 100 on the large screen 111 of the television receiver 110, entertainment such as a videophone and a game machine can be enjoyed not only by the user but also by everyone.

  Moreover, since a dedicated cable is not required, the user's economic burden can be reduced.

  Since sound is transmitted by FM (frequency modulation) in the frequency band of the television receiver 110, the sound quality is high.

  Moreover, since information is output from the antenna for television transmission / reception of the mobile terminal device 100, a new dedicated connector is not required, the terminal of the mobile terminal device 100 and the connector installation space can be used effectively, and the enlargement of the mobile terminal device is suppressed. can do.

  In addition, images, music, and videos can be shared between portable terminal devices with a television tuner. Furthermore, it can be used like a transceiver in combination with a portable terminal device with a television tuner.

  Note that these functions are not limited to fixed television receivers, and can also be applied to mobile television receivers. If the device has an infrared communication port, the channel used for transmission can be transmitted to other devices by infrared communication. For example, information searched by the portable terminal device can be displayed on the display screen of the car navigation system at the destination.

  Next, an embodiment will be described in which an audio signal is transmitted from a mobile terminal device 100 to an external device having a radio broadcast receiving function using radio broadcast. As an example of the external device, for example, headphones having an FM broadcast wave receiving function can be applied.

  In the case of this example, the digital / NTSC conversion circuit 302 shown in FIG. 3 is not necessary, and instead of the TV transmission circuit 303, a radio broadcast wave output unit that FM-modulates the audio signal 305 and transmits it from the antenna 304 to the outside is provided. Just do it.

  Also in this example, as in the case of transmitting the above-mentioned television broadcast wave, an empty channel survey unit investigates an empty channel in a frequency band of radio broadcast, for example, FM broadcast wave. Then, the control unit 220 determines the vacant channel detected by the vacant channel checking unit as a channel to be used when transmitting an FM-modulated audio signal. Then, according to the instruction of the control unit 220, the audio signal is output to the antenna using the empty channel and transmitted to an external device.

  In the above example, FM modulated broadcast waves are used, but AM modulated broadcast waves can be similarly applied. In addition, when a stationary radio, a radio cassette deck, or the like is used as an external device, it can be used in place of the speaker of the mobile terminal device, and can be viewed with high sound quality. Alternatively, when a general-purpose small radio integrated with a wireless earphone is used, it can be used as a wireless earphone of a portable terminal device.

  Further, although the digital / NTSC conversion circuit 302 shown in FIG. 3 has been described as converting a digital video signal to an NTSC video signal, it can also be applied to a PAL system. For example, the input digital video signal 306 may be converted into an NTSC video signal or a PAL video signal in accordance with the method of the transmission destination television receiver 110.

  According to the configuration described above, an audio signal is transmitted on a radio broadcast wave from a mobile terminal device to an external device, and the audio signal is transmitted using the radio broadcast reception function of the external device without modifying the external device on the receiving side. Can be played in a higher sound quality environment.

  In addition to the video displayed on the display screen of the mobile terminal device, a video signal recorded in a memory or the like of the mobile terminal device may be transmitted to an external device such as a television receiver for display. At this time, a list of video signals that can be transmitted may be displayed (listed up) on the video signal transmission menu screen so that the user can select. Similarly, an audio signal recorded in a memory or the like of the mobile terminal device may be transmitted to an external device such as a television receiver to reproduce the audio.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can naturally be made without departing from the scope of the present invention.

It is the figure which represented the concept of this invention typically. It is the figure which showed the block structural example of the portable terminal device which concerns on the example of 1 embodiment of this invention. It is a block diagram of the TV transmission unit in the portable terminal device which concerns on the example of 1 embodiment of this invention. It is the flowchart which showed the various setting processes in the portable terminal device which concerns on the example of 1 embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Portable terminal device, 102 ... Image (video), 103 ... Frequency charged wave of television broadcasting, 110 ... Television receiver, 111 ... Display unit, 207 ... Display unit, 208 ... Infrared communication unit, 220 ... Control unit 301 ... TV transmission unit 302 ... Digital / NTSC conversion circuit 303 ... TV transmission circuit 304 ... antenna

Claims (9)

A mobile terminal device comprising at least a display unit for displaying video, an audio output unit for emitting audio, and an antenna for transmitting television broadcast waves,
A television broadcast wave transmitting means for outputting a video signal and / or an audio signal from the antenna to an external device having a television broadcast wave reception function using radio waves of a predetermined channel in a television broadcast frequency band is provided. Mobile terminal device. The television broadcast wave transmitting means includes
A video signal converter for converting a digital video signal into an analog video signal;
A television broadcast wave output unit that modulates the analog video signal and the audio signal converted by the video signal conversion unit so as to be transmitted as the television broadcast wave and outputs the modulated signal to the antenna; The portable terminal device according to claim 1. An empty channel investigation section that investigates empty channels in the television broadcast frequency band,
A control unit configured to set a channel of the external device based on an empty channel detected by the empty channel survey unit;
An infrared communication unit that performs infrared communication with the external device;
The control unit transmits the video signal to the external device using the empty channel by the television broadcast wave transmitting means, and transmits channel setting information to the external device via the infrared communication unit. The mobile terminal device according to claim 1. The control unit further sets a sound volume when the audio signal transmitted from the external device is reproduced according to a predetermined condition,
Receiving the transmission command, transmitting volume setting information to the external device via the infrared communication unit, and reproducing the audio signal transmitted to the external device at a volume based on the volume setting information. The portable terminal device according to claim 3. The control unit measures the distance between the mobile terminal device and the external device using infrared rays output from the infrared communication unit, and sets the volume of the external device according to the distance obtained by the measurement. The mobile terminal device according to claim 4. The mobile terminal device according to claim 4, wherein the control unit sets a volume of the external device according to a time of a day. It has a sound collection unit that converts sound into electrical signals,
The mobile terminal device according to claim 4, wherein the control unit sets a volume of the external device according to a volume of sound collected by the sound collection unit. An information transmission method for transmitting a video signal from a mobile terminal device having a television broadcast wave transmission function to an external device having a television broadcast wave reception function,
Investigate available channels in the television broadcast frequency band,
Superimposing the video signal on the radio wave of an empty channel in the television broadcast frequency band,
In response to an external transmission command, the video signal is transmitted to the external device on an empty channel radio wave in the television broadcast frequency band, and the information on the empty channel is transmitted by infrared communication.
The information transmission method characterized by matching the channel setting of the external device with the empty channel and displaying the video signal transmitted to the external device on the display screen of the external device using the empty channel. Furthermore, the volume at which the external device reproduces the audio signal is set according to a predetermined condition,
In response to the transmission instruction, the audio signal is transmitted to the external device on an empty channel radio wave in the television broadcast frequency band, and the volume setting information is transmitted by infrared communication.
The information transmission method according to claim 8, wherein the audio signal transmitted to the external device is reproduced at a volume based on the transmitted setting information.

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