JPH03264883A - Information apparatus - Google Patents

Abstract

PURPOSE:To prevent an information sound from being heard by persons other than a specified user, by using a so-called parametric speaker as an electroacoustic transducer delivering the information sound. CONSTITUTION:An ultrasonic wave transmitter-receiver 1 constructed of a vibrator array prepared by arranging a large number of ultrasonic vibrators 2 is connected selectively to a sensor processing element and an aural signal outputting element through a mode change-over switch SW1. A detection output is inputted to a control circuit 6, while the aural signal outputting element is connected to the transmitter- receiver 1. A primary sound wave containing the opposite side-band components above and below a fundamental frequency F0 is outputted from the transmitter-receiver 1, and a secondary sound wave of an audio frequency is generated as a beat component corresponding to a frequency difference between the opposite side-band components by the interference of the primary sound wave. Since the directivity of the secondary sound generated by a nonlinear parametric operation is somewhat weaker than that of the primary sound wave, a detection area of an object does not accord with an area of propagation of the secondary sound wave in a state of an information sound being outputted. As the result, the information sound can be prevented from being heard by persons other than a specified user.

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a notification device equipped with an electroacoustic transducer that generates an audible secondary sound wave by a nonlinear parametric action of a primary sound wave including a plurality of frequency components. BACKGROUND OF THE INVENTION Conventionally, notification devices have been provided in exhibition halls, storefronts, etc., which send out messages explaining exhibits and products when a person comes to a specific location. For example, as shown in Fig. 8, a notification device C that detects a visitor using an object detection sensor A and notifies a greeting message using a voice output device B, or as shown in Fig. 9, at a painting exhibition, There is a notification bag ffc that detects when a person stands in front of each painting and outputs a message explaining the painting. For audio output in such notification devices, electrodynamic speakers are often used as electroacoustic transducers that output audible sounds based on input signals. Here, A shown in FIGS. 8 and 9 indicates the detection area by the object detection sensor A, and the mouth indicates the notification area by the audio output device.

[Problem to be solved by the invention]

By the way, the above-mentioned electrodynamic speaker has relatively weak directivity, so if the notification device WC is placed close to each other, messages from other notification devices C may be confused and difficult to hear. The problem arises that it becomes difficult. To solve this problem, it is necessary to improve the directivity of the speaker so that only the user can hear the notification sound. In order to strengthen the directivity of an electrodynamic speaker, it is possible to increase the diameter or attach a larger horn, but in any case, the effect of improving directivity is small despite the increase in size, and the problem is insufficient. This is something that cannot be resolved. The present invention aims to solve the above problems, and although it is relatively small, it increases the directivity so that the output sound can be heard only in a specific place, even when different sounds are output in nearby places. The present invention aims to provide a notification device that prevents audio confusion from occurring.

[Means to solve the problem]

In the configuration of claim 1, in order to achieve the above object, a sound source that generates a primary sound wave including a plurality of frequency components is provided.
It has an electroacoustic transducer that outputs a high-frequency sound through the nonlinear parametric action of the next sound wave, and an object detection sensor that produces a detection output when an object is detected. It sends out an audible notification sound. In the configuration of claim 2, the object detection sensor is configured to transmit and receive ultrasonic waves using an ultrasonic transducer to detect the presence or absence of an object, and when a detection output is obtained, the ultrasonic transducer is identified as a sound source. It will become. In the structure of claim 3, the ultrasonic transducer is a transducer array in which a plurality of ultrasonic transducers are arranged, and when used as an object detection sensor and when used as a sound source, each ultrasonic transducer is It changes the terms of use.

[Effect]

According to the configuration of claim 1, since a so-called parametric speaker is used as the electroacoustic transducer for transmitting the notification sound, high directivity can be obtained despite being relatively small. As a result, the notification sound can be prevented from being heard by anyone other than a specific user. A parametric speaker generates a notification sound that is more audible than a primary sound wave based on the following principle. In other words, as shown in Fig. 6, a sound source 1 such as a speaker or an ultrasonic transducer outputs two types of sound waves with different frequencies (F 1 , F 2 >2) as primary sound waves (solid line). Then, due to the interference between both first-order sound waves, a difference component (F1-F2>) and a sum component (F1+F2) of the frequencies of both first-order sound waves appear (see Figure 7), and the frequency difference between the first-order sound waves is the audible frequency. If so, an audible secondary sound wave (dashed line) will be generated as a difference component.This phenomenon is called a nonlinear parametric effect, and the directionality of the generated secondary sound wave is the same as the first-order sound wave. Although the directionality is weaker than that of sound waves, it shows a pattern that is relatively close to secondary sound waves (in the elliptical pattern in Figure 6, the solid line corresponds to the primary sound wave and the broken line corresponds to the secondary sound wave).
. Therefore, if ultrasonic waves with strong directivity are used as the primary sound waves, the directivity can be increased even at audible frequencies. According to the structure of claim 2, since the ultrasonic transducer used when detecting an object is also used as a sound source for generating the notification sound, it is not necessary to separately arrange the ultrasonic transducer and the sound source. This saves space and makes construction easier. According to the structure of claim 3, in addition to the structure of claim 2, since the ultrasonic transducer is composed of a transducer array in which a plurality of ultrasonic transducers are arranged, the primary sound wave transmitted from the sound source is The ultrasonic output level of 1 can be increased, and 1
It is possible to output audible sound obtained by interference of secondary sound waves at a practical level. :i. Since the usage conditions of each ultrasonic transducer are changed depending on whether it is used as an object detection sensor or as a sound source, it is difficult to determine which ultrasonic transducer to use. The strength of directivity and the direction of the maximum level can be adjusted by changing the conditions of use, such as what phase of the input signal is applied. Furthermore, as mentioned above, secondary sound waves have weaker directivity than primary sound waves, so if an ultrasonic transducer is used under the same conditions both when detecting an object using ultrasonic waves and when notifying an audible sound, This will change the directivity, but it is possible to match the directivity by changing the conditions of use.

【Example】

As shown in FIG. 1, the ultrasonic transducer 1 is constituted by a transducer array in which a large number of ultrasonic transducers 2 are arranged. The ultrasonic transducer 1 is selectively connected to a sensor processing section and an audio signal output section via a mode changeover switch SW1. The sensor processing unit includes a wave transmitting circuit 3 that transmits ultrasonic waves, a wave receiving circuit 4 that receives ultrasonic waves, and a signal processing circuit 5 that determines the presence or absence of an object based on the received ultrasonic waves. . The transmission circuit 3 and the delivery date n4 are the transmission/reception changeover switch SW.
2, etc., to the ultrasonic transducer 1. Separate ultrasonic transducers for transmission and delivery,
By devising the circuit configuration, the transmission/reception changeover switch SW2 can be omitted. For example, as shown in FIG. 4, if the ultrasonic transducer 2a for transmitting waves and the ultrasonic transducer 2b for receiving waves are used separately, the transmission/reception changeover switch SW2 can be omitted, and the entire ultrasonic vibration Power consumption is also reduced compared to the case where the child 2 is driven for wave transmission. Furthermore, some of the ultrasonic transducers 2 may not be used for transmitting and receiving waves.The sensor processing unit intermittently sends out pulsed ultrasonic waves until reflected waves are obtained from the transmitted ultrasonic waves. The present invention is configured to detect the presence or absence of an object within a predetermined distance range based on the time of , or to detect the presence or absence of an object based on the frequency shift of the reflected wave due to the Doppler effect. Conventionally known configurations can be used for these configurations. In this way, when the presence of an object is detected, a detection output is obtained. The obtained detection output is input to the control circuit 6, a mode changeover switch SW is switched, and an audio signal output section is connected to the ultrasonic transducer 1. The audio signal output section includes an audio signal generation circuit 7 and an output circuit 8. As shown in FIG. 2, the audio signal generation circuit 7 includes an audible signal generation circuit 11 that outputs an audible signal of an audible frequency upon receiving a detection output inputted from the sensor processing section via the control circuit 6; It is equipped with a carrier wave oscillation circuit 12 that outputs a carrier wave signal of the fundamental frequency F0 of a sound wave, and a modulation circuit 13 that modulates the carrier wave signal with an audible signal. The signal is amplified and input to the ultrasonic transducer 1. The audible signal generation circuit 11 generates an audible signal such as a single tone or a synthesized voice. However, as shown in Fig. 3, the ultrasonic transducer l outputs a primary sound wave containing both side wave components centered around the fundamental frequency F0 of the carrier signal, and due to the interference of the primary sound wave, the both side wave components are A secondary sound wave with an audible frequency is generated as a beet acid component corresponding to the frequency difference between the two. By the way, secondary sound waves generated by nonlinear parametric effects have slightly weaker directivity than primary sound waves (see Figure 6), so it is important to use head-mounted detection while detecting an object and to output notification sounds. This does not match the propagation area of the secondary sound wave when it is being output.Also, when detecting an object, it is necessary to limit the detection area to prevent reflected waves from objects that are not the detection target. In general, the greater the number of ultrasonic transducers 2 to drive, the stronger the directivity, so directivity can be adjusted by adjusting the number of ultrasonic transducers 2 to drive. By adjusting the position of the ultrasonic transducer 2, it is also possible to control the shape of the object detection area and the notification sound propagation area.Furthermore,
As shown in FIG. 5, if each ultrasonic transducer 2 is driven via an individual phase shifter 9 and the phase of the signal input to each ultrasonic transducer 2 is controlled, the fifth In the figure (a
) (b) It becomes possible to make the directivity pattern ff1Nll like each pattern shown as (c). In this way, it is possible to change the directivity pattern to i%I7m by adjusting the conditions of use, and by changing the conditions of use when detecting an object and when sending out the notification sound, it is possible to achieve the desired result. A directional pattern can be obtained.

【Effect of the invention】

As described above, in the configuration of M'SP and term 1, a so-called parametric speaker is used as an electroacoustic transducer for transmitting the notification sound, so high directivity can be obtained despite the relatively small size. As a result, there is an effect that the notification sound can be prevented from being heard by anyone other than a specific user. In the configuration of claim 2, although the ultrasonic transducer used when detecting an object is also used as a sound source for generating the notification sound, there is no need to separately arrange the ultrasonic transducer and the sound source, This has the advantage of saving space and making construction easier. In the structure of claim 3, in addition to the structure of claim 2, since the ultrasonic transducer is composed of a transducer array in which a plurality of ultrasonic transducers are arranged, the ultrasonic wave as a primary sound wave transmitted from the sound source is The output level of the sound waves can be increased, and the audible sound obtained by the interference of the primary sound waves can be outputted at a practical level. In addition, since the usage conditions of each ultrasonic transducer are changed depending on whether it is used as an object detection sensor or as a sound source, it is important to know which ultrasonic transducer to use and what type of ultrasonic transducer to use. By changing usage conditions such as whether to apply an input signal with a certain phase, the directivity strength and the direction of the maximum level can be adjusted.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a block diagram showing an audio signal output section in the same as above, FIG. FIG. 5 is a main part block diagram showing another embodiment of the present invention,
FIG. 6 is an explanatory diagram of the principle of the parametric speaker used in the above, FIG. 7 is an explanatory diagram of the operation of the parametric speaker used in the same, and FIGS. 8 and 9 are explanatory diagrams showing how the notification device according to the present invention is used. be. 1... Ultrasonic transducer, 2... Ultrasonic vibrator, 3...
... Wave transmitting circuit, 4... Delivery circuit, 5... Signal processing circuit, 6... Control circuit, 7... Audio signal generation circuit, 8
... Output circuit, 9... Phase shifter. Figure 5

Claims (3)

[Claims] (1) An electroacoustic transducer that includes a sound source that generates a primary sound wave containing multiple frequency components and outputs an audible sound through a nonlinear parametric action of the primary sound wave, and an object detection sensor that provides a detection output when an object is detected. What is claimed is: 1. An annunciation device comprising: an audible annunciation sound that is transmitted from an electroacoustic transducer when a detection output is obtained. (2) The object detection sensor is configured to detect the presence or absence of an object by transmitting and receiving ultrasonic waves using an ultrasonic transducer,
The notification device according to claim 1, wherein the ultrasonic transducer becomes the sound source when a detection output is obtained. (3) The ultrasonic transducer is a transducer array in which a plurality of ultrasonic transducers are arranged, and the usage conditions of each ultrasonic transducer are different when used as an object detection sensor and when used as a sound source. 3. The notification device according to claim 2, wherein the notification device changes.