Limited area voice publicity system

Abstract

Provided is a limited area voice publicity system including a plurality of signal transmission devices (10) and a signal reception device (20) for receiving signals output from the signal transmission devices, wherein: each signal transmission device comprises an A / D conversion unit (13) that receives the voice of a speaker and converts the voice into a digital signal, a modulation unit (14) that generates a PWM optical signal on the basis of the digital signal, and an optical signal transmission unit (15) that transmits the PWM optical signal in a predetermined direction; and the signal reception device (20) comprises an optical signal reception unit (21) that receives the PWM optical signal transmitted from the optical signal transmission unit, a binarization circuit (23) that binarizes the PWM optical signal received by the optical signal reception unit, a low pass filter (25) that removes a high-frequency component greater than or equal to a carrier included in the binarized signal, and a voice output unit (27) that is driven by the signal passed through the low pass filter.

Description

Limited Area Audio Public Relations System

[0001] The present invention relates to a limited area audio public relations system that can be suitably used to listen to the audio of a specific speaker in a space where multiple speakers are giving presentations simultaneously.

[0002] At exhibitions and poster sessions at academic conferences, multiple speakers give presentations simultaneously in one venue. At these exhibitions and poster sessions, the audience typically moves to the booth or poster of the exhibit that interests them and listens to the speaker's explanation.

[0003] When multiple speakers give presentations at the same time in a single venue, even if the audience tries to listen to a specific speaker's explanation near that speaker, the speech of the speakers nearby becomes noise and makes it difficult to hear. In addition, multiple speakers may use small loudspeakers to attract the audience's attention, which increases the noise level in the venue and makes it even more difficult to hear the specific speaker's explanation.

[0004] In response to this, a system has been proposed in which different sounds are output in a plurality of specific areas provided in one space.

[0005] For example, Patent Document 1 describes an audio guidance system that includes an audio guidance device that provides commentary on paintings exhibited in each of multiple sections of an exhibition space in an art museum, and a receiving device carried by the user. The audio guidance device has an infrared emitting module that emits audio signals and synchronization signals as infrared rays to each section. The receiving device receives the infrared rays emitted from the audio guidance device, demodulates them using a demodulation module and a synchronization adjustment module, and outputs the audio.

[0006] Patent Document 2 describes an information guidance system that includes a receiver that can be attached to glasses or clothing, and a transmitter that is placed in a predetermined area and transmits prepared audio information via infrared light after FM modulation. In this system, when a user wearing the receiver enters the transmission range of the transmitter, the system receives the infrared light emitted from the transmitter, demodulates it, generates audio data, and outputs it from earphones or the like.

[0007] JP 2002-215077 A JP 2003-199142 A

[0008] The systems described in Patent Documents 1 and 2 read and play pre-prepared audio data and are not intended for use by an audience to listen to a speaker's voice in real time. However, the configurations described in Patent Documents 1 and 2 transmit a digitized audio signal together with a synchronization signal via infrared, or FM-modulate audio data and transmit it via infrared, which is then received by a terminal device, demodulated, and output as audio data. Therefore, if the configuration is changed to collect the audio spoken by the speaker in each area on the spot, it is conceivable that the systems could be used to allow an audience to listen to the audio spoken by the speaker in real time.

[0009] However, in the system of Patent Document 1, if the synchronization signal cannot be received correctly, the audio signal associated with that synchronization signal cannot be demodulated. At an exhibition or other venue where many audience members are moving around, infrared rays are likely to be blocked by other audience members. If the synchronization signal cannot be acquired, the audio may be interrupted or noise, including unusual sounds, may occur, making it difficult to hear the audio. Furthermore, receiving a digital signal and converting it into audio requires not only a circuit for receiving and demodulating the digital signal, but also a circuit for converting it into an analog signal, and a digital signal processing circuit such as a CPU for removing noise, which results in a complex circuit configuration for the terminal device and high power consumption.

[0010] Furthermore, in the system of Patent Document 2, in order to receive an FM signal and convert it into audio, a circuit combining, for example, a band-limiting filter, an amplitude limiter, a frequency-voltage conversion circuit, a power amplifier circuit, etc. is required, which again makes the circuit configuration of the terminal device complex and increases power consumption.

[0011] As such, none of the technologies proposed to date are suitable for use in a space where multiple speakers are giving presentations simultaneously, allowing an audience to selectively listen to the voice of any speaker, and a new system is needed.

[0012] The problem to be solved by the present invention is to provide a system suitable for allowing an audience to selectively listen to the voice of any speaker in a space where multiple speakers are giving presentations simultaneously.

[0013] The present invention, which has been made to solve the above-mentioned problems, is a limited area audio public relations system including a plurality of signal transmitting devices and a signal receiving device that receives signals output from the plurality of signal transmitting devices, wherein each of the plurality of signal transmitting devices comprises: a) an A / D conversion unit that receives a speaker's voice and converts it into a digital signal; b) a modulation unit that generates a PWM optical signal based on the digital signal; and c) an optical signal transmitting unit that transmits the PWM optical signal in a predetermined direction; and the signal receiving device comprises: d) an optical signal receiving unit that receives the PWM optical signal transmitted from the optical signal transmitting unit; e) a binarization circuit that binarizes the PWM optical signal received by the optical signal receiving unit; f) a low-pass filter that removes high frequency components above the carrier frequency contained in the binarized signal; and g) an audio output unit that is driven by a signal that has passed through the low-pass filter.

[0014] The limited-area audio public relations system of the present invention is used in a space where multiple speakers (speakers) are giving presentations simultaneously, allowing an audience (listeners) to selectively listen to the voice of any speaker. A signal transmission device is provided for each of the multiple speakers. Listeners carry signal reception devices and approach speakers of interest. In the limited-area audio public relations system of the present invention, the A / D conversion unit in the signal transmission device first receives the speaker's voice and converts it into a digital signal, the modulation unit generates a PWM optical signal based on the digital signal, and the optical signal transmission unit transmits the PWM optical signal in a predetermined direction. The PWM optical signal may be generated by digital processing or may be generated using a carrier such as a sawtooth wave or a triangular wave, as is conventionally known.

[0015] When the signal receiving device receives an optical signal output from the optical signal transmitting unit, it binarizes the PWM optical signal using a binarization circuit to remove amplitude components, and then uses a low-pass filter to remove high-frequency components above the carrier frequency to extract an audio signal.The audio signal then drives an audio output unit to output audio.If the intensity of the PWM optical signal received by the optical signal receiving unit is low, the PWM optical signal can be amplified as necessary before being binarized by the binarization circuit.

[0016] Because the PWM signal used in this invention is an analog signal, the original audio information can be obtained simply by removing the carrier using a low-pass filter. Therefore, unlike when using digital signals, there is no need to use a demodulation circuit, and there is no risk of audio being interrupted or noise, including abnormal sounds, due to failure to acquire a synchronization signal. Furthermore, there is no need for complex circuits; a simple circuit can be used, and it can operate with low power.

[0017] The limited area audio public relations system according to the present invention further comprises an inverse phase signal generating circuit for generating an inverse phase signal of the binarized signal, and the low-pass filter preferably further removes high frequency components contained in the inverse phase signal.

[0018] In the limited-area audio public relations system of the above embodiment equipped with a reverse-phase signal generation circuit, in addition to the signal (positive-phase signal) digitized by the binarization circuit, a reverse-phase signal is generated, and the high-frequency components are removed from these signals using a low-pass filter to drive the audio output unit. This forms a BTL (Balanced Transformer Less) circuit of a type known as a class D or switching power amplifier, which is considered to be the most efficient, and enables the audio output unit to be driven at a low voltage and output audio at a sufficient volume.

[0019] In the limited area audio public relations system according to the present invention, it is preferable that the audio output unit is an earphone or a headphone.

[0020] In the limited-area audio public relations system of the above aspect, by outputting audio from earphones or headphones, each listener can hear the audio of a specific speaker without being disturbed by audio output from the audio output units of signal receiving devices carried by other listeners. In addition, the limited-area audio public relations system of the above aspect can reduce noise within the venue.

[0021] The present invention provides a system suitable for allowing an audience to selectively listen to the voice of any speaker in a space where multiple speakers are giving presentations simultaneously.

[0022] The present invention relates to a limited area audio public relations system and a signal receiving device.

[0023] An embodiment of a limited-area audio public relations system according to the present invention will be described below with reference to the drawings. The limited-area audio public relations system of this embodiment is used in an exhibition hall where multiple corporate booths are set up in one venue. The limited-area audio public relations system of this embodiment includes multiple signal sending devices 10 and multiple signal receiving devices 20.

[0024] FIG. 1 is an overall view of an exhibition hall 1 in which the limited-area audio public relations system of this embodiment is used. In this example, booths A to K of 11 companies are set up in the single space of the exhibition hall 1. Each booth A to K exhibits the products of the respective company, and speakers A1 to K1 from each company give explanations about them. The audience listens to the explanations from speakers A1 to K1 of companies in which they are interested. In FIG. 1, speakers A1 to K1 (speakers) are indicated by circles, and the audience (listeners) are indicated by triangles.

[0025] Figure 2 shows the main components of a signal transmission device 10 used by speakers A1-K1 in their respective booths A-K. The signal transmission device 10 includes a microphone 11 that collects the sounds emitted by speakers A1-K1, an amplifier 12 that amplifies the analog signal of the weak sounds collected by the microphone 11 to a required voltage level, an A / D converter 13 that converts the amplified sound signal into a digital signal, a PWM modulator 14 that pulse-width modulates (PWM) the digital signal converted by the A / D converter 13, and an infrared transmitter 15 that emits a PWM optical signal. An infrared LED light source 16 is connected to the infrared transmitter 15. Each of these components can be implemented using conventionally known circuits. The A / D converter 13 and PWM modulator 14 can be configured as separate components, or they can be configured using a one-chip microcomputer such as a PIC (Peripheral Interface Controller) and software. With the above configuration, the signal transmission device 10 transmits a PWM optical signal.

[0026] As shown in Figure 3, in this embodiment, each unit of the signal transmission device 10 is built into the microphone used by the speakers A1 to K1. Multiple infrared LED light sources 16 are arranged at the bottom end of the microphone so that the emitted optical signal can reach a wide audience. Therefore, when the speakers A1 to K1 hold the microphone and speak to the audience, the bottom end of the microphone faces the audience, and as a result, the PWM optical signal is transmitted widely to the audience.

[0027] The infrared LED light source 16 is configured to emit infrared light of a predetermined intensity over a predetermined angular spread. This irradiation angle should be as wide as possible, preferably at least 90 degrees or more in the horizontal direction. This allows the PWM optical signal to be transmitted over a wide area around the speakers A1 to K1. In this embodiment, the PWM optical signals transmitted from the signal transmission devices 10 used by different speakers A1 to K1 are shown with an irradiation angle of 90 degrees, resulting in an overlapping area between the optical signals of adjacent signal transmission devices 10.

[0028] 3, the various components of the signal transmission device 10 are built into the microphone, but the optical signal transmission unit 15 may be housed in a single housing, and the housing may be attached to the upper wall of the booth so that a PWM optical signal is transmitted from the infrared LED light source 16 toward the audience, with the optical signal transmission unit 15 and the microphone connected by wire or wirelessly (Bluetooth (registered trademark) or the like). This allows the optical signal transmission unit 15 to be installed in a high position, making it easier to avoid light being blocked by the audience.

[0029] Figure 4 shows the main components of a signal receiving device 20 used by exhibition attendees. The signal receiving device 20 includes a photodetector 21 that receives the PWM optical signal transmitted from the infrared LED light source 16 of the signal transmitting device 10, an amplifier 22 that amplifies the received PWM optical signal to the required voltage, a binarization unit 23 that digitizes the amplified signal, a BTL switching amplifier 24 that generates a signal with the opposite phase to the binarized signal, a low-pass filter 25 that removes the carrier (and higher-frequency components) contained in the switching BTL signal to extract the audio signal, a volume control unit 26 that adjusts the volume, and earphones 27 that play audio driven by the audio signal adjusted by the volume control unit 26. The signal receiving device 20 also includes a power indicator LED light source 28 that lights up when the power is on, and a power switch 29 for turning the power on and off.

[0030] The reception range (light-receiving angle) of the optical signal by the light-receiving element 21 is preferably 90 degrees or less in the horizontal direction. The light-receiving angle is more preferably 60 degrees or less in the horizontal direction, and even more preferably 30 degrees or less. In cases where the transmission ranges of PWM optical signals from signal transmission devices 10 used by multiple speakers overlap, as in this embodiment, limiting the light-receiving angle can prevent simultaneous reception of PWM optical signals transmitted from multiple signal transmission devices 10. Alternatively, a movable light-shielding portion may be provided on the outside of the light-receiving element 21, and the light-receiving angle can be changed by the light-shielding portion. This allows the light-receiving angle to be adjusted to suit the location where the signal receiving device 20 is used.

[0031] 5 shows an example of the configuration of the signal receiving device 20. This signal receiving device 20 comprises an ear-hook type main body 31 and a rod-shaped extension part 32 extending forward from the top of the main body 31, with the light receiving element 21 located at the front end of the extension part 32. This prevents the PWM optical signal transmitted from the signal transmitting device 10 from being blocked by hair or the like. The main body 31 also has a curved part 311 (a part for attaching to the user), which can be hooked onto the ear to allow the listener to wear the device on their own ear.

[0032] The main body 31 houses the amplifier 22, binarization unit 23, BTL switching amplifier 24, and low-pass filter 25. In addition, the outer edge of the main body 31 is provided with a dial that serves as the volume adjustment unit 26, a power indicator LED light source 28, and a power switch 29. Furthermore, an electric wire 33 extends from the base end of the extension portion 32 to send the audio signal adjusted by the volume adjustment unit 26 to the earphone 27. With this configuration, the signal receiving device 20 can be fitted to either the left or right ear.

[0033] Of course, the configuration shown in FIG. 4 is just an example, and the device may be attached to the audience member's own clothing or accessories.

[0034] Next, the operation of the limited area voice public information system of this embodiment will be described.

[0035] At booths A to K of each company set up in the exhibition hall 1, speakers A1 to K1 of each company hold a microphone configured as a signal transmission device 10 with the side equipped with an infrared LED light source 16 facing the audience, and give explanations of their company's products.

[0036] The audience at the exhibition receives the signal receiving device 20 at the reception desk before entering the exhibition hall 1. The audience turns on the power by operating the power switch 29 of the received signal receiving device 20, hangs the main body 31 over their ears, and wears the earphones 27 on their ears. This causes the light receiving element 21 to face forward (to be positioned in front of the audience). As mentioned above, the audience is represented by the black ▼ in Figure 1, and the angle of this represents the light receiving range of the light receiving element 21.

[0037] At the exhibition hall 1, the infrared LED light source 16 of the signal transmission device 10 used by each speaker A1-K1 transmits the processed PWM optical signal over a predetermined angular spread (e.g., 90 degrees) and a predetermined range (e.g., a range of 5 m from the infrared LED light source 16; the hatched range A2-K2 in Figure 1). As an audience member approaches a booth A-K that interests them and faces the signal transmission device 10, they enter the PWM optical signal transmission range A2-K2 of the signal transmission device 10 used by one of the speakers A1-K1. The signal receiving device 20 receives the PWM optical signal, and the speaker's voice is output from the earphone 27. The audience member adjusts the volume of the voice output from the earphone 27 by appropriately adjusting the volume control unit 26 to listen to the explanations by the speakers A1-K1. When the audience walks toward the booth and turns their eyes to the speaker, they naturally face the infrared LED light source 16 of the signal transmission device 10 and the PMW optical signal is received by the light receiving element 21 .

[0038] In the situation shown in Figure 1, for example, audience member A3 is standing in front of booth B. By directing his gaze toward speaker A1, only speaker A1 is included in the light receiving range of the light receiving element 21, allowing him to hear speaker A1's explanation. Also, audience member B3 is standing in front of booth A. By facing speaker B1 directly, only speaker B1 is included in the light receiving range, allowing him to hear speaker B1's explanation. In this way, by emitting a PWM optical signal over a wide angle from the infrared LED light source 16 of the signal transmission device 10 and narrowing the light receiving angle of the audience-side light receiving element 21, audience members can hear the intended speaker's explanation even if a large number of audience members gather at one booth and the audience spreads out beyond the booth. Similarly, audience members C3, D3, F3, H3, I3, and J3 can hear speakers C1, D1, F1, H1, I1, and J1, respectively. The signal receiving device 20 of the audience X, which is located outside the range of the PWM optical signal transmission from the signal transmitting device 10, does not receive the PWM optical signal of any speaker.

[0039] When multiple speakers from different companies are simultaneously explaining their products at a single venue, such as at an exhibition, the audience typically moves to the booth or poster of the exhibit that they are interested in to listen to the speaker's explanation. However, when multiple speakers are simultaneously explaining their company's products at a single venue, even if the audience tries to listen to a specific speaker's explanation near the speaker's booth, there is a problem in that the voices of other speakers in nearby booths become noise and make it difficult to hear the speaker.

[0040] Furthermore, even if a system designed for a different purpose is repurposed, a system such as that described in Patent Document 1 transmits a digital signal, for example, a combination of a 2-bit start bit, an 8-bit audio signal, and a 1-bit stop bit. Therefore, if the infrared light is blocked by other listeners and the synchronization signal fails to be acquired, the audio may be interrupted or noise, including abnormal sounds, may be generated, making it difficult to hear. Furthermore, receiving a digital signal and converting it to audio requires not only a circuit for receiving and demodulating the digital signal, but also a circuit for converting it to an analog signal and a digital signal processing circuit such as a CPU for removing noise, which results in a complex circuit configuration for the terminal device and high power consumption. Furthermore, a system such as that described in Patent Document 2 requires a circuit combining a band-limiting filter, an amplitude limiter, a frequency-to-voltage conversion circuit, a power amplifier circuit, etc., which also results in a complex circuit configuration for the terminal device and high power consumption.

[0041] In contrast, the PWM signal used in the limited-area audio public information system of this embodiment is an analog signal, so the original audio information can be obtained simply by removing the carrier using a low-pass filter. Therefore, unlike when using digital signals, there is no need to use a demodulation circuit, and there is no risk of audio interruptions or abnormal noise due to failure to acquire a synchronization signal. Furthermore, there is no need to use complex circuits; the system can be configured with a simple circuit and can operate with low power consumption.

[0042] Furthermore, in the limited-area audio public relations system of this embodiment, when an audience member moves through the exhibition hall and enters the PWM optical signal transmission range of any of the signal transmission devices 10, the voice of the speaker A1 to K1 using that signal transmission device 10 is automatically output from the earphones 27. Therefore, an audience member can listen to the explanation of any speaker at any booth by simply going near the booth A to K that interests them (PWM optical signal transmission range) and facing the speaker A1 to K1 directly, without having to operate a signal receiving device.

[0043] Furthermore, in the limited area audio public relations system of this embodiment, the speakers A1 to K1 do not need to speak loudly, so the exhibition hall is quiet and the audience can clearly hear the explanations by the speakers A1 to K1.

[0044] The above embodiment is merely an example and can be modified as appropriate in accordance with the spirit of the present invention.

[0045] In the above embodiment, an example of using a limited area audio public relations system at an exhibition venue 1 was described, but the limited area audio public relations system of the present invention can be used in various situations where multiple speakers make presentations simultaneously at one venue, such as a poster session at an academic conference or a student research presentation at a super science high school.

[0046] In the above embodiment, the signal receiving device 20 is in the form of an earphone, but it may be carried by the audience around the neck or held in the hand. Also, various configurations are possible, such as making the main body 31 a clip type that can be put in a breast pocket or the like, and making the light receiving element 21 a clip type that can be attached to glasses or the like.

[0047] Aspects It will be apparent to those skilled in the art that the exemplary embodiments described above are examples of the following aspects.

[0048] (Item 1) One aspect of the present invention is a limited area audio public relations system including a plurality of signal transmitting devices and a signal receiving device that receives signals output from the plurality of signal transmitting devices, wherein each of the plurality of signal transmitting devices comprises: a) an A / D conversion unit that receives a speaker's voice and converts it into a digital signal; b) a modulation unit that generates a PWM optical signal based on the digital signal; and c) an optical signal transmitting unit that transmits the PWM optical signal in a predetermined direction; and the signal receiving device comprises: d) an optical signal receiving unit that receives the PWM optical signal transmitted from the optical signal transmitting unit; e) a binarization circuit that binarizes the PWM optical signal received by the optical signal receiving unit; f) a low pass filter that removes high frequency components above the carrier contained in the binarized signal; and g) an audio output unit that is driven by a signal that has passed through the low pass filter.

[0049] (Clause 2) The limited area audio public relations system according to clause 2 is the limited area audio public relations system according to clause 1, further comprising an inverse phase signal generating circuit that generates an inverse phase signal of the binarized signal, and the low-pass filter further removes high frequency components contained in the inverse phase signal.

[0050] (Clause 3) The limited area audio public relations system according to clause 3 is the limited area audio public relations system according to clause 1 or 2, wherein the audio output unit is an earphone or a headphone.

[0051] (4) The limited area audio public relations system according to 4 is the limited area audio public relations system according to any one of 1 to 3, wherein the signal transmission device is built into a microphone.

[0052] (Clause 5) The limited area audio public relations system according to clause 5 is the limited area audio public relations system according to any one of clauses 1 to 4, wherein the signal receiving device is provided with a wearing part for being worn by a user of the signal receiving device.

[0053] DESCRIPTION OF SYMBOLS 1...Exhibition hall 10...Signal transmission device 11...Microphone 12...Amplification section 13...A / D conversion section 14...PWM modulation section 15...Optical signal transmission section 16...Infrared LED light source 20...Signal reception device 21...Optical signal receiving element 22...Amplifier 23...Binarization section 24...BTL switching amplifier 25...Low-pass filter 26...Volume adjustment section 27...Earphone 28...Power indicator LED light source 29...Power switch 31...Main body 311...Bending section 32...Extension section 33...Electric wire

Claims

1. A limited-area voice public relations system including a plurality of signal transmitting devices and a signal receiving device that receives signals output from the plurality of signal transmitting devices, Each of the aforementioned plurality of signal transmission devices, a) An A / D conversion unit that receives the speaker's voice and converts it into a digital signal, b) A modulation unit that generates a PWM signal by pulse width modulation of the digital signal, c) An optical signal transmission unit that generates a PWM optical signal from the PWM signal and transmits it in a predetermined direction. Equipped with, The aforementioned signal receiving device d) An optical signal receiving unit that receives the PWM optical signal transmitted from the optical signal transmitting unit, e) A binarization circuit that binarizes the PWM optical signal received by the optical signal receiving unit, f) A low-pass filter that removes high-frequency components above the carrier contained in the binarized signal, g) Audio output section driven by the signal that has passed through the low-pass filter and A limited-area voice public relations system characterized by comprising the following features.

2. moreover, Inverse phase signal generation circuit that generates an inverse phase signal of the binarized signal. Equipped with, The low-pass filter further removes high-frequency components contained in the inverted-phase signal. A limited-area voice public relations system according to claim 1, characterized in that

3. The limited-area voice publicity system according to claim 1, characterized in that the voice output unit is an earphone or headphones.

4. The limited-area voice public relations system according to claim 1, characterized in that the signal transmission device is built into the microphone.

5. The signal receiving device has a mounting part for being attached to the user of the signal receiving device. A limited-area voice public relations system according to claim 1, characterized by comprising the above.