JP4802990B2 - Wireless headphone system - Google Patents

Description

  The present invention digitally modulates a stereo audio signal including left and right audio, and receives an audio signal transmission device that transmits the modulated signal by wireless communication, and a signal wirelessly transmitted from the audio signal transmission device, The present invention relates to a headphone device that outputs a digitally demodulated stereo sound signal to a sound output unit.

  Conventionally, wireless headphones capable of receiving a stereo audio signal from an audio playback device such as a CD player by wireless communication are known (for example, Patent Documents 2 and 3). According to this wireless headphone, there is an advantage in that the listener is not restricted in movement because a troublesome cord connected to the audio reproduction device is not required.

  In general, stereo headphones that support L / R 2ch stereo audio output have their left and right mounting directions determined, and therefore it is necessary to correctly align the left and right directions when mounting. However, with headphones having a shape that is symmetric or close to left and right, it is difficult to distinguish between left and right at a glance.

  Therefore, in Patent Document 1, a reception unit capable of receiving a detection signal transmitted from the audio transmission device (rear display unit) is provided before and after one speaker (audio output unit) of the wireless headphones, and the received detection signal is received. A wireless headphone system has been proposed in which the left and right wearing states of headphones are recognized by comparing the strengths of the headphones and the L / R channel to be output is automatically switched. Further, it is disclosed that as a detection signal, infrared rays or light may be used in addition to radio waves.

JP 2005-333428 A JP 7-327300 A JP 2005-286919 A

  However, in the wireless headphone system described in Patent Document 1, the detection signal receiving unit for determining the wearing state of the headphones is provided separately from the audio signal receiving unit, and thus the configuration is complicated. There is. In addition, since there is only one audio signal receiving unit, there is a problem that the sound quality output from the speaker of the headphones deteriorates when the reception state is deteriorated due to the state of the transmission path.

  In addition, in a wireless headphone system using infrared communication, a plurality of infrared light receiving units are generally provided in a headphone device in order to widen the range in which infrared signals can be received. However, after synthesizing infrared signals received by multiple infrared receivers, they are demodulated and output as audio, so if a signal that cannot be corrected by noise or error is received by an infrared receiver, it is demodulated. There is a risk that the quality of the output audio will be degraded. Conventionally, in order to simplify the circuit configuration, it is considered that the received infrared signal is synthesized and then demodulated.

  The present invention is a wireless headphone system that digitally modulates a stereo audio signal reproduced by an audio reproduction device, transmits the signal to a headphone device by wireless communication (particularly, infrared communication), and outputs the sound. It is an object of the present invention to provide a wireless headphone system capable of recognizing the sound and automatically switching the L / R channel to output sound and realizing high-quality sound output.

  The present invention has been made to achieve the above object, and digitally modulates a stereo audio signal including left and right audio, and transmits the modulated signal by wireless communication, and the audio signal. A headphone device that receives a signal wirelessly transmitted from a transmission device and outputs a digitally demodulated stereo sound signal from a first sound output unit or a second sound output unit, the wireless headphone system comprising: The apparatus is provided in at least two places (for example, before and after either one of the left and right speakers), and includes a radio signal receiving unit capable of receiving a radio signal from the audio signal transmitting device and the plurality of radio signal receiving units. Error detection means for detecting an error rate when each received radio signal is digitally demodulated, and detected by the error detection means Based on the error rate, a mounting direction determination unit that determines the mounting direction of the headphone device, and outputs of left and right audio signals that are digitally demodulated according to the mounting direction determined by the mounting direction determination unit Out of the radio signals received by the plurality of radio signal receiving units based on the output destination setting means for setting the destination (first or second audio output unit) and the error rate detected by the error detecting means Output signal selection means for outputting left and right audio signals obtained by demodulating the radio signal with the lowest error rate to the set output destination.

  For example, when the left and right audio output units (speakers) of the headphone device have the same shape, the left and right audio output units are difficult to understand at first glance, but the present invention eliminates the need to distinguish between the left and right audio output units.

  The wireless signal receiving unit includes a first wireless signal receiving unit provided at a position for mainly receiving a wireless signal from the front of the listener when the listener wears the headphones, and a wireless signal from the rear of the listener. And a second wireless signal receiving unit provided at a position where the signal is mainly received. Accordingly, it is possible to reliably determine the front and rear when the listener wears the headphone device, that is, which radio signal receiving unit faces the audio signal transmitting device side, so that the wearing direction can be accurately determined.

  For example, when a wireless signal receiving unit is provided before and after the first audio output unit, it is determined that the first wireless signal receiving unit is in front (on the audio signal transmitting device side) (for example, the first wireless signal receiving unit). If the error rate of the radio signal from the signal receiving unit is low), the left audio is output from the first audio output unit, and the right audio is output from the second audio output unit, When the second radio signal receiving unit is determined to be in front (for example, when the error rate of the infrared signal from the second radio signal receiving unit is low), conversely, the left audio from the second audio output unit It is sufficient to set so that the signal is output and the right audio signal is output from the first audio output unit.

  Further, the wireless signal is an infrared signal. This makes it difficult for the wireless signal receiving unit (infrared light receiving unit) to receive infrared signals from directions other than the light receiving direction, so that the difference in error rate of the received infrared signals becomes significant, and the orientation of the headphone device is changed. Accurate judgment can be made.

  Further, the mounting direction determination unit determines a mounting direction of the headphone device based on an error rate of a radio signal received within a predetermined time, and the output destination setting unit is determined by the mounting direction determination unit. The first and second audio output units, which are the output destinations of the left and right digitally demodulated audio signals, are set according to the direction of attachment, and until a predetermined operation is performed (for example, for the headphone device) This setting is maintained until the power is turned off. For example, a wearing detection means for detecting that the listener has worn the headphone device is provided so that the power of the headphone device is turned on when the headphone device is worn. It is desirable to determine automatically.

  As a result, after the output destination (first or second audio output unit) is set based on the mounting direction of the headphone device, the listener moves around the location, and the radio signals are received by the respective radio signal receiving units. Even if the error rate of the received signal changes, the set mounting orientation is not changed. On the other hand, since the audio signal output to the audio output unit is an audio signal obtained by always demodulating a signal with a low error rate, high sound quality can be maintained.

  And a signal level detecting unit that detects a signal level (reception strength) of the radio signals received by the plurality of radio signal receiving units, wherein the mounting direction determining unit includes the error rate detected by the error detecting unit and The mounting direction of the headphone device is determined based on the signal level detected by the signal level detection means. Thereby, since the superiority or inferiority of the received radio signal becomes remarkable, it is possible to improve the accuracy of determining the mounting direction of the headphone device.

  According to the present invention, in the wireless headphone system, the headphone device determines the mounting direction (left and right) of the headphone device based on the error rate of the radio signal (infrared signal) detected by the error detection means, and is determined. While setting the output destination (first or second audio output unit) of the left and right digitally demodulated audio signals according to the mounting direction, the radio signal with the lowest error rate is set based on the error rate. Since the stereo audio signal (left and right audio signals) obtained by demodulating the sound is output to the set output destination, it can be installed without distinguishing the left and right of the headphone device, and high-quality sound can be output from the audio output unit. Can be output.

  For example, even if a radio signal received by one radio signal receiver cannot be corrected, a stereo audio signal obtained by demodulating a radio signal received by another radio signal receiver is output. Therefore, the sound quality output from the audio output unit does not deteriorate because the received plurality of radio signals are not synthesized.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a wireless headphone system according to the present invention, and FIG. 2 is a perspective view of a headphone device 20 configuring the wireless headphone system according to the present invention.
The wireless headphone system according to the present embodiment includes an audio signal transmitting device 10 connected to an audio reproducing device 30 such as a CD player, and a headphone device 20.

  The audio signal transmitting device 10 digitally modulates the stereo audio signal (left and right audio signals) output from the audio reproducing device 30, and transmits the modulated signal to the headphone device 20 by infrared communication.

  On the other hand, the headphone device 20 receives the infrared signal transmitted from the sound signal transmitting device 10 and outputs a stereo sound signal obtained by digitally demodulating the infrared signal to the first sound output unit or the second sound output unit. In the following description, the left speaker 26L in FIGS. 1 and 2 is a first audio output unit, and the right speaker 26R is a second audio output unit.

  The first audio output unit 26L and the second audio output unit 26R have shapes that can be worn on either the left ear or the right ear.

  In addition, the headphone device 20 includes an infrared light receiving unit 21 as a wireless signal receiving unit that receives an infrared signal from the audio signal transmitting device 10. The infrared light receiving unit 21 includes, for example, a first infrared light receiving element (first wireless signal receiving unit) 21a and a second infrared light receiving element (second wireless signal receiving unit) 21b on the top and bottom surfaces of a cylindrical body. And is horizontally disposed above the second audio output unit 26R so that infrared signals from the front and rear of the listener can be received mainly when the listener wears the headphone device 20. In addition, you may make it arrange | position the infrared rays light-receiving part 21 above the 1st audio | voice output part 26L.

Next, specific configurations of the audio signal transmission device 10 and the headphone device 20 that constitute the wireless headphone system of the present embodiment will be described.
FIG. 3 is a block diagram of the audio signal transmitting apparatus 10. As shown in FIG. 3, the audio signal transmitting apparatus 10 includes audio signal input terminals 15L and 15R that can input a stereo audio signal from the audio reproducing apparatus 30, an A / D conversion unit 14, a digital modulation unit 13, A driver amplifier 12 and an infrared light emitting element 11 are provided.

  The L / R stereo audio signal from the audio reproduction device 30 is input to the audio signal transmission device 10 via the audio signal input terminals 15L and 15R, and is digitally converted by the A / D conversion unit 14. The digitally converted digital audio signal is subjected to predetermined digital modulation processing in the digital modulation unit 13, and the modulated signal is amplified by the driver amplifier 12 and transmitted from the infrared light emitting element 11 to the headphone device 20.

  FIG. 4 is a block diagram of the headphone device 20. As shown in FIG. 4, the headphone device 20 includes first and second infrared light receiving elements 21a and 21b, I / V conversion amplifiers 22a and 22b, a digital demodulator 23, a microcomputer 24, and a D / A conversion. Unit 25, a first audio output unit 26L, and a second audio output unit 26R.

  Infrared signals received by the infrared light receiving elements 21a and 21b are amplified by the I / V conversion amplifiers 22a and 22b, and subjected to predetermined digital demodulation processing by the digital demodulation unit 23. The demodulated L / R stereo audio signal is separated into left and right audio signals L and R by the D / A converter 25 and converted into analog signals, and then the first audio output unit 26L and the second audio output unit 26R. Is output from.

  The microcomputer 24 detects an error rate when the digital demodulation unit 23 digitally demodulates the two infrared signals received by the first and second infrared light receiving elements 21a and 21b (error detection means). Then, based on the detected error rate, the mounting direction of the headphone device 20 is determined (wearing direction determining means). Further, the signal levels of the two infrared signals received by the first and second infrared light receiving elements 21a and 21b are detected (signal level detecting means), and based on the detected error rate and signal level, By determining the mounting direction of the headphone device 20, the determination accuracy can be improved.

  Further, the microcomputer 24 determines which audio output units 26L and 26R are to output the digitally demodulated left and right audio signals L and R, respectively, according to the mounting direction of the headphone device 20, and sets the output destination ( Output destination setting means).

  Further, the microcomputer 24 first or second outputs a stereo audio signal based on the infrared signal having the lower error rate, out of the two infrared signals received by the infrared light receiving elements 21a and 21b, based on the error rate of the infrared signal. 2 output to the audio output unit 2 (output signal selection means).

  FIG. 5 is a flowchart showing audio output processing executed in the headphone device 20. Note that the determination of the wearing state (wearing direction) of the headphone device 20 is performed in a state where the listener wears the headphone device 20 and faces the audio signal transmitting device 10. That is, the error rate is lower for the infrared signal received by the infrared light receiving unit facing the audio signal transmitting apparatus.

  First, in step S101, it is determined whether the power of the headphone device 20 is turned on. When it is determined that the power of the headphone device 20 is turned on, the process proceeds to step S102, and when it is determined that the power of the headphone device 20 is not turned on, the processing is ended as it is. The power may be automatically turned on when the listener wears the headphone device.

  Next, it is determined whether the first and second infrared light receiving elements 21a and 21b have received the infrared signal transmitted from the audio signal transmitting device 10 (step S102). If it is determined that the infrared signal has been received, the process proceeds to step S103. If it is determined that the infrared signal has not been received (for example, the power of the audio signal transmission device is not turned on), the process is terminated. .

  Next, in step S103, the error rates of the respective infrared signals received by the first and second infrared light receiving elements 21a and 21b are acquired, and it is determined which of the infrared signals has a lower error rate (step S104).

  If it is determined in step S104 that the error rate of the infrared signal received by the first infrared light receiving element 21a is low, the left audio signal L is set to be output to the first audio output unit (left speaker) 26L. Then, the second audio output unit (right speaker) 26R is set to output the right audio signal R (step S105). That is, the low error rate of the infrared signal received by the first infrared light receiving element 21a means that the first infrared light receiving element 21a faces the audio signal transmitting device 10 side. This is because the audio output unit 26L is attached to the left ear and the second audio output unit 26R is attached to the right ear.

  Then, stereo audio signals L and R obtained by demodulating the infrared signal with a low error rate received by the first infrared light receiving element 21a are output to the set audio output units 26L and 26R.

  On the other hand, if it is determined in step S104 that the error rate of the infrared signal received by the second infrared light receiving element 21b is low, the right audio signal R is output to the first audio output unit (left speaker) 26L. To set the left audio signal L to be output to the second audio output unit (right speaker) 26R (step S107). That is, the low error rate of the infrared signal received by the second infrared light receiving element 21b means that the second infrared light receiving element 21b faces the audio signal transmitting device 10 side. This is because the audio output unit 26R is attached to the left ear and the first audio output unit 26L is attached to the right ear.

  And the stereo audio | voice signal L and R based on the infrared signal with a low error rate received with the 2nd infrared light receiving element 21b is output to the set audio | voice output parts 26L and 26R.

  As described above, in the present embodiment, the mounting direction (left and right) of the headphone device 20 is determined based on the error rate of the infrared signal received when the headphone device 20 is turned on, and the headphone device 20 is mounted according to the mounting direction. Thus, it is determined whether the output destinations of the left and right audio signals are the first and second audio output units 26L and 26R. Further, this setting is preferably held until a predetermined operation is performed (for example, until the power of the headphone device is turned off).

  Thereby, after the output destination (first or second audio output unit) is set based on the mounting direction of the headphone device 20, the reception state by the infrared light receiving elements 21 a, 21 b, such as when the listener moves from place to place. Even if the (error rate) is reversed, the output destinations of the left and right audio signals (first or second audio output units 26L and 26R) are not changed.

  On the other hand, since the audio signals output from the audio output units 26L and 26R always have a low error rate, high sound quality can be maintained. Note that the audio output (steps S106 and S108) in the flowchart of FIG. 5 shows the case where the headphone device is turned on. After that, an infrared signal with a low error rate is selected and demodulated. The obtained sound is output.

  Thus, in the wireless headphone system of the present embodiment, the headphone device 20 determines the mounting direction (left and right) of the headphone device 20 based on the error rate of the infrared signal received by the infrared light receiving units 21a and 21b, The output destinations (first or second audio output units) of the left and right digitally demodulated audio signals are set according to the determined mounting orientation. Further, based on the error rate of the infrared signal received by the infrared light receivers 21a and 21b, the stereo audio signal (left and right audio signals) obtained by demodulating the infrared signal with the lower error rate is set to the set output destination. Output. Accordingly, the sound output units 26L and 26R of the headphone device 20 can be mounted without distinguishing left and right, and high-quality sound can be output from the sound output units 26L and 26R.

  As mentioned above, although the invention made by this inventor was concretely demonstrated based on embodiment, this invention is not limited to the said embodiment, It can change in the range which does not deviate from the summary.

  For example, in the above embodiment, the mounting direction of the headphone device 20 is determined based on the error rate of the infrared signal received by the infrared light receiving unit 21, but not only the error rate of the infrared signal but also the signal level ( It is also possible to determine the mounting direction of the headphone device with reference to (reception intensity). Usually, the signal level should be higher when the error rate of the infrared signal is lower. Thereby, since the superiority or inferiority of the received radio signal becomes remarkable, it is possible to improve the accuracy of determining the mounting direction of the headphone device.

  In the above-described embodiment, the headphone device 20 is configured to include two infrared light receiving elements 21a and 21b that can receive infrared signals from the front and rear. However, an infrared light receiving element is further provided. Also good. For example, it can be provided on the side surfaces of the audio output units 26L and 26R. Thereby, even when the listener moves and becomes perpendicular to the audio signal transmission device 10, for example, the infrared signal can be received with high sensitivity, so that high sound quality can be maintained. Even in this case, the mounting direction of the headphone device 20 may be determined based on the infrared signals from the first and second infrared light receiving elements.

  Furthermore, in the above embodiment, stereo audio signals are transmitted to the headphone device 20 using infrared communication, but general wireless communication such as radio waves can also be used. However, using infrared communication makes it difficult to receive infrared signals from directions other than the light receiving direction, and the difference in error rate of received infrared signals becomes more prominent. It is considered that infrared communication is more suitable.

  The audio signal input from the audio reproduction device 30 to the audio signal transmission device 10 may be an optical digital signal in addition to an analog signal.

1 is a schematic configuration diagram of a wireless headphone system according to the present invention. 1 is a perspective view of a headphone device 20. FIG. 1 is a block diagram of an audio signal transmission device 10. FIG. 2 is a block diagram of a headphone device 20. FIG. 5 is a flowchart showing audio output processing executed in the headphone device 20.

Explanation of symbols

20 Headphone device 21 Infrared light receiver (radio signal receiver)
21a 1st infrared light receiving element (1st radio signal receiving part)
21b Second infrared light receiving element (second wireless signal receiving unit)
22a, 22b I / V conversion amplifier 23 Digital demodulator 24 Microcomputer (error detection means, mounting direction determination means, output destination setting means, output signal selection means)
25 D / A conversion unit 26L first audio output unit 26R second audio output unit

Claims (6)

An audio signal transmitting device that digitally modulates a stereo audio signal including left and right audio, and transmits the modulated signal by infrared communication; and
A headphone device that receives an infrared signal transmitted from the sound signal transmitting device and outputs a digitally demodulated stereo sound signal from a first sound output unit or a second sound output unit; ,
The headphone device is
A first infrared light receiving portion provided at a position for mainly receiving an infrared signal from the front of the listener when the listener wears the headphones, and a first infrared light receiving portion provided at a position for mainly receiving the infrared signal from the rear of the listener. Two infrared receivers;
Error detection means for detecting an error rate when each of the infrared signals received by the first and second infrared light receiving units is digitally demodulated;
Signal level detection means for detecting the signal level of the infrared signal received by the first and second infrared light receivers;
Wearing direction determining means for determining the mounting direction of the headphone device based on the error rate and signal level of the infrared signal received and detected within a predetermined time;
Output destination setting means for setting respective output destinations of the left and right digitally demodulated audio signals according to the mounting direction determined by the mounting direction determining means, and holding this setting until a predetermined operation is performed; ,
Based on the error rate detected by the error detection means, left and right audio signals obtained by demodulating the infrared signal having the lower error rate among the infrared signals received by the first and second infrared light receiving units. Output signal selection means for outputting to the set output destination, a wireless headphone system. An audio signal transmitting apparatus that digitally modulates a stereo audio signal including left and right audio, and transmits the modulated signal by wireless communication;
A headphone device that receives a signal wirelessly transmitted from the sound signal transmitting device and outputs a digitally demodulated stereo sound signal from a first sound output unit or a second sound output unit; ,
The headphone device is
A radio signal receiver provided in at least two locations and capable of receiving a radio signal from the audio signal transmitter;
Error detection means for detecting an error rate when each of the radio signals received by the plurality of radio signal receiving units is digitally demodulated;
Based on the error rate detected by the error detection unit, a mounting direction determination unit that determines the mounting direction of the headphone device;
Output destination setting means for setting the output destinations of the left and right digitally demodulated audio signals according to the mounting direction determined by the mounting direction determining means;
Based on the error rate detected by the error detection means, the left and right audio signals obtained by demodulating the radio signal having the lowest error rate among the radio signals received by the plurality of radio signal receiving units are set. An output signal selection means for outputting to an output destination.   The wireless signal receiver includes a first wireless signal receiver provided at a position that mainly receives a wireless signal from the front of the listener when the listener wears the headphones, and a wireless signal from the rear of the listener. The wireless headphone system according to claim 2, further comprising: a second wireless signal receiving unit provided at a receiving position.   The wireless headphone system according to claim 2, wherein the wireless signal is an infrared signal. The wearing direction determining means determines a mounting direction of the headphone device based on an error rate of a radio signal received and detected within a predetermined time,
The output destination setting means sets the first and second audio output units that are output destinations of the left and right audio signals that are digitally demodulated according to the mounting direction determined by the mounting direction determination means. The wireless headphone system according to any one of claims 2 to 4, wherein the setting is held until a predetermined operation is performed. Comprising signal level detection means for detecting the signal level of the radio signal received by the plurality of radio signal receivers,
3. The wearing direction determining unit determines a mounting direction of the headphone device based on an error rate detected by the error detecting unit and a signal level detected by the signal level detecting unit. To 5. The wireless headphone system according to any one of 5.

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