JP5370206B2 - Vehicle presence notification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicle presence notification device capable of lowering generated sound pressure of "high frequency notification sound" in a maintained effect of making the presence of a vehicle easy to be noticed. <P>SOLUTION: The vehicle presence notification device "intermittently generates" the "high frequency notification sound (4 kHz)" as notification sound. As a result, the "high frequency notification sound" becomes easy to be noticed, and the "high frequency notification sound" is capable of exerting the same effect as "continuous generation of loud sound", even if generated sound pressure of the "high frequency notification sound" is lowered. By lowering the generated sound pressure of the "high frequency notification sound", a failure that the "high frequency notification sound" reaches persons having no needs to be notified of the presence of the vehicle can be suppressed. Even if notification sound is masked by environmental sound, the "intermittent high frequency notification sound" can be recognized, and the presence of the vehicle can be noticed. Further, the generated sound pressure of the notification sound is lowered to suppress battery consumption. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a vehicle presence notification device that notifies the presence of a vehicle to the outside of a vehicle by a notification sound, and in particular, traveling by an electric motor that generates rotational power by energization, such as an electric vehicle, a fuel cell vehicle, and a hybrid vehicle. The present invention relates to a technique for informing the outside of a vehicle of the existence of a possible vehicle.

Vehicles with low running noise, such as vehicles that run on electric motors, have the disadvantage that pedestrians are less likely to notice the vehicle.
Therefore, a “notification sound (such as an acoustic signal for notifying the vehicle approach)” is generated from a dynamic speaker (speaker that directly radiates audible sound) attached to the vehicle to the outside of the vehicle, so that pedestrians around the vehicle can Proposals have been made to inform the existence (see, for example, Patent Document 1).

The notification sound is a sound that is generated to notify the “pedestrian who wants to notify the presence of the vehicle” of the presence of the vehicle, and is therefore required to be easily noticed by a person.
Therefore, it is conceivable to generate a “high-frequency notification sound” having a high frequency (for example, 4 kHz) that is easily attached to a person's ear as a notification sound so that the person can easily notice it.
In addition, it is conceivable that a notification sound of “loud sound” is generated to make it easy for people to notice.

In this way, by generating a “high-frequency notification sound” having a high frequency as a “loud sound”, it can be easily noticed by a person.
However, the “high-frequency notification sound” is easily noticed, but is a “touching sound”.
For this reason, if the “high-frequency notification sound” accompanied by an unpleasant feeling is generated as a “loud sound”, the “high-frequency notification sound” reaches a person far away from the vehicle (a person who does not need to notify the presence of the vehicle).

JP 2007-203924 A

  The present invention has been made in view of the above-described problems, and its object is to reduce the sound pressure generated by a “high-frequency notification sound” having a high frequency while maintaining the effect of making the presence of the vehicle easy to notice. An object of the present invention is to provide a vehicle presence notification device.

[Means of Claim 1]
The vehicle presence notification apparatus adopting the means of claim 1 is a low-frequency-related low-frequency notification sound having a high frequency that is easily attached to a human ear and a high-frequency notification sound at a lower frequency than the high-frequency notification sound. The frequency notification sound is generated, and the high frequency notification sound in the frequency range of 3 kHz to 7 kHz among the overtones is generated intermittently .
In this way, by “intermittently generating” “high frequency notification sound” of 3 kHz to 7 kHz of overtones , the “high frequency notification sound” can be easily noticed. As a result, even if the sound pressure of the “high frequency notification sound” is lowered, it is possible to maintain the effect that the presence of the vehicle is easily noticed. In other words, it is not necessary to generate a “high-frequency notification sound” with a “loud sound”, and it is possible to suppress a problem that the “high-frequency notification sound” reaches a person far away from the vehicle (a person who does not need to notify the existence of the vehicle). Can do.

Also, even if the notification sound is masked by the environmental noise, “intermittent high frequency notification sound” can be recognized from the environmental noise by “intermittently generating” the “high frequency notification sound”. Can do.
For this reason, even in a situation where the notification sound is masked by the environmental noise, the possibility of notifying the notification sound and notifying the presence of the vehicle increases.

Furthermore, the generated sound pressure of the notification sound (the sound pressure of the entire notification sound) can be decreased with the decrease in the generated sound pressure of the “high frequency notification sound”.
Thereby, it is possible to suppress the power consumption necessary for generating the notification sound, and consequently it is possible to suppress the power consumption of the battery.

By including “low frequency notification sound (low frequency sound with high frequency notification sound as harmonic overtone)” in “high frequency notification sound”, the notification sound including “high frequency notification sound” can be softened. The discomfort given can be kept small.
In addition, since the “high frequency notification sound” and the “low frequency notification sound” have a harmonic relationship, if there is a missing fundamental (lost base tone: harmonic relationship), a low tone that is not actually included can be heard. The illusion phenomenon) can be expected to soften the notification sound by supplementing even low sounds that do not actually exist with the illusion, and the discomfort given to the person can be further reduced.
Thus, by including the “low frequency notification sound” in the “high frequency notification sound”, it is possible to suppress the discomfort that the notification sound including the “high frequency notification sound” gives to the person.

[Means of claim 2 ]
The “low frequency notification sound” in the vehicle presence notification device of the means of claim 2 is “generated continuously”.

[Means of claim 3 ]
The “low frequency notification sound” in the vehicle presence notification device of the means of claim 3 is “intermittently generated”.
In addition, the intermittent "low frequency alarm sound"
(I) It may be intermittent at the same time as the “high-frequency notification sound”,
(Ii) The “high frequency notification sound” may be interrupted at a timing opposite to that of the “high frequency notification sound”, or (iii) the “high frequency notification sound” may be interrupted at a timing unrelated to the “high frequency notification sound”. .

[Means of claim 4 ]
The “low frequency notification sound” in the vehicle presence notification device of the means of claim 4 includes half the frequency of the “high frequency notification sound”.
As a result, even if the elderly person cannot hear the “high-frequency notification sound”, the “low-frequency notification sound that is half the high-frequency notification sound (for example, 2 kHz if the high-frequency notification sound is 4 kHz)” is easily noticed by the elderly person. As a result, even if it is an elderly person, the possibility of knowing the existence of the vehicle with a high probability by the notification sound increases.

[Means of claim 5 ]
The “low frequency notification sound” in the vehicle presence notification device according to the means of claim 5 is composed of a plurality of frequencies having a harmonic relationship.
As a specific example,
When the frequency of the “high frequency notification sound” is A,
The frequency of the “low frequency notification sound” is A × (1/2) ⁿ ,
And it is comprised by the continuous integer of n = 1-3, or the continuous integer of n = 1-4.
Thus, the discomfort of the notification sound can be suppressed by using a plurality of “low frequency notification sounds” having a harmonic relationship and increasing the frequency components that do not feel unpleasant.
In addition, by using a plurality of “low frequency notification sounds” that are related to overtones, the above-mentioned missing fundamental effect (effect of adding a pseudo low tone) can be enhanced. The effect of softening can be enhanced.

[Means of claim 6 ]
The “low frequency notification sound” in the vehicle presence notification device of the means of claim 6 includes a frequency lower than at least 1 kHz.
Thus, by including a frequency lower than 1 kHz as the “low frequency notification sound”, the effect of softening the notification sound is increased, and the discomfort given to the person can be reduced.

[Means of Claim 7 ]
According to a seventh aspect of the present invention, there is provided a vehicle presence notification device that emits a notification sound toward the outside of a vehicle by a parametric speaker.
By using a parametric speaker that has strong directivity and can generate a notification sound at a position away from the vehicle, the notification sound can be generated only in a “predetermined range where the presence of the vehicle is to be notified”.
For this reason, generation | occurrence | production of the notification sound to the range which does not need to alert | report the presence of a vehicle can be suppressed, and the vehicle noise to the vehicle periphery can be suppressed as a result.

[Means of Claim 8 ]
The parametric speaker of the means of claim 8 is:
An ultrasonic speaker,
A notification sound signal generator for generating a “frequency signal that forms a notification sound”;
An ultrasonic amplitude modulator that modulates the “frequency signal that generates the notification sound” to “amplitude change of voltage (or current) oscillated at the ultrasonic frequency”;
It is configured using a speaker driving unit that drives an ultrasonic speaker by an “amplitude signal of an ultrasonic frequency” amplitude-modulated by the ultrasonic amplitude modulation unit.

[Means of Claim 9 ]
The vehicle presence notification apparatus according to the means of claim 9 reads “high-frequency notification sound in environmental noise”. Then, the sound pressure level of the “high-frequency notification sound in the notification sound” is increased by a predetermined sound pressure from the sound pressure level of the read “high-frequency notification sound in the environmental noise”.
As a result, the sound pressure level of the “high-frequency notification sound” in the notification sound is automatically adjusted according to the environmental noise, and the sound pressure level of the “high-frequency notification sound” in the notification sound does not lose to the environmental noise. The problem that the sound pressure level of the “high-frequency notification sound” becomes unnecessarily large can be suppressed.
As a result, the presence of the vehicle can be notified with high probability by the “high-frequency notification sound” in the notification sound, and the generation of noise can be suppressed.

It is a time chart for operation | movement description (Example 1). 1 is a schematic configuration diagram of a vehicle presence notification device (Example 1). It is the front view and top view of an ultrasonic speaker (Example 1). (Example 1) which is a principle explanatory drawing of a parametric speaker. (Example 1) which is a graph which shows the relationship between the frequency characteristic of environmental noise, and the sound pressure level of the "high frequency notification sound" in notification sound. (Example 2) which is a time chart for operation | movement description.

As a notification sound, the vehicle presence notification device
“High-frequency notification sound” consisting of a high frequency (for example, a frequency selected from a frequency range of 3 kHz to 7 kHz) that is easily attached to the human ear is “intermittently generated” at regular intervals.

The “ high frequency notification sound” includes a “low frequency notification sound” having a harmonic relationship with the “high frequency notification sound” .
Notification sound generated by the car both presence notification apparatus is,
(I) It may be composed of only the “high frequency notification sound” and the “low frequency notification sound”,
(Ii) The “high frequency notification sound” and the “low frequency notification sound” may be configured by adding a frequency component that forms another sound.

Also ,
(I) The “low frequency notification sound” may be “continuously generated” (see Example 1 described later),
(Ii) The “low frequency notification sound” may be “intermittently generated” (see Example 2 described later).

Furthermore, the notification sound generated by the vehicle presence notification device is
(I) A parametric speaker may be used to generate a notification sound consisting of an audible sound at a location away from the vehicle.
(Ii) A notification sound composed of an audible sound may be generated from a vehicle using a dynamic speaker or the like that directly generates an audible sound.

Next, a specific example of the vehicle presence notification device will be described with reference to FIGS.
Example 1 shows an example in which a notification sound including an audible sound is generated at a place away from a vehicle using a parametric speaker as a specific example of the vehicle presence notification device.

[Configuration of Example 1]
As shown in FIG. 2, the vehicle presence notification device according to the first embodiment includes an ultrasonic speaker 1 that can irradiate ultrasonic waves, and a main body device 2 that controls the operation of the ultrasonic speaker 1.
(Description of ultrasonic speaker 1)
The ultrasonic speaker 1 is attached to, for example, a front portion of a vehicle so as to emit generated ultrasonic waves toward the outside of the vehicle.

A specific example of wearing the ultrasonic speaker 1 is shown.
In the case of a vehicle equipped with an engine (an internal combustion engine that generates rotational output by combustion of fuel) such as a hybrid vehicle, the ultrasonic speaker 1 is provided with an outside air intake opening (provided at the front of the vehicle) provided with a radiator grille. The vehicle traveling wind intake that cools the radiator is mounted inside the intake of the cooling traveling wind in the case of an electric vehicle or the like that does not have a radiator. It is provided so as to discharge toward the front outside the vehicle (for example, obliquely forward toward the sidewalk).

The mounting position of the ultrasonic speaker 1 is not limited to the front part of the vehicle. For example, when the ultrasonic speaker 1 is mounted on the rear part of the vehicle or the lower surface of the vehicle and the vehicle is traveling backward (backward traveling). The notification sound may be radiated toward the rear periphery of the vehicle.
Moreover, the irradiation direction of the ultrasonic wave in the ultrasonic speaker 1 may be fixed in a fixed direction, or may be a switchable radiation direction according to the vehicle driving situation or the like. Here, as the means for switching the ultrasonic irradiation direction, a plurality of ultrasonic speakers 1 having different radiation directions may be mounted and switched, or the support portion of the ultrasonic speaker 1 may be an electric actuator (solenoid or the like). It is also possible to drive by switching.

A specific structural example of the ultrasonic speaker 1 will be described with reference to FIG.
The ultrasonic speaker 1 is equipped with a plurality of piezoelectric speakers 3 (ceramic speakers, piezo speakers, etc.) that generate air vibrations having a frequency (20 kHz or higher) higher than the human audible band. As shown in FIG. 3A, the speaker array is configured by being appropriately arranged.
Here, the ultrasonic wave has strong directivity. That is, ultrasonic waves have a strong straightness of propagation in the air. For this reason, the ultrasonic speaker 1 can irradiate ultrasonic waves only in a specific direction (the direction in which the presence of the vehicle is desired to be transmitted: for example, diagonally forward toward the sidewalk) with respect to the vehicle.

  The piezoelectric speaker 3 is suitable for ultrasonic reproduction, and includes a piezoelectric element (an example of a driver) that expands and contracts according to an applied voltage (charge / discharge), a diaphragm that vibrates air by the expansion and contraction of the piezoelectric element, and a piezoelectric element. It has a well-known structure composed of an element and a support frame that supports the diaphragm.

The ultrasonic speaker 1 can control the amount of energy of the generated ultrasonic waves and the directivity range of the ultrasonic waves radiated from the piezoelectric speakers 3 depending on the number and arrangement of the piezoelectric speakers 3 to be used. Further, the directivity range of ultrasonic waves can also be controlled by using a horn part 4 (which may be a duct part forming an acoustic path) provided around the front surface (in the direction of ultrasonic irradiation) of the speaker array. it can.
In this embodiment, an example in which the piezoelectric speaker 3 is used as a specific example of the ultrasonic wave generation means is shown. However, the present invention is not limited to the piezoelectric speaker 3, and other types of ultrasonic waves can be used as long as the ultrasonic waves can be reproduced. Generation means may be used.

(Description of main device 2)
Next, the main body device 2 that drives the ultrasonic speaker 1 will be described.
The main unit 2 includes a notification sound signal generation unit 5 that creates a frequency signal that forms a notification sound, an ultrasonic amplitude modulation unit 6 that modulates the frequency signal of the notification sound to an ultrasonic frequency, and an ultrasonic speaker with a modulated ultrasonic frequency. 1 is provided, and is operated by receiving an operation signal (notification sound generation signal) from an ECU (abbreviation of engine control unit) or the like.
The main unit 2 is mounted on the main unit 2 by being connected to means for automatically adjusting the output level (volume) of the ultrasonic speaker 1 based on the environmental noise of the vehicle (described later) and an in-vehicle power source such as an in-vehicle battery. And a power supply unit (not shown) for supplying electric power necessary for the operation of each circuit (electrical functional component).

Below, each said means mounted in the main body apparatus 2 is demonstrated.
The notification sound signal generation unit 5 is a means for generating a plurality of frequency signals (synthetic waveform signals) that form a notification sound.
(I) a plurality of oscillators;
(Ii) a digital sound wave generation technique (computer) for creating an arbitrary waveform signal (a plurality of frequency signals forming a notification sound) based on a clock signal generated by a reference clock (crystal oscillator);
(Iii) A synthesizer technique (analog circuit or analog circuit combined with a computer) that extracts an arbitrary frequency signal (frequency signal forming a notification sound) from a pink noise (or white noise) generated by a noise source by a comb filter. Also good)
Either of these is used.

The notification sound of this Example 1 is
(I) “High-frequency notification sound” composed of a high frequency (a high frequency that a person generally feels uncomfortable) that is easily attached to a human ear;
(Ii) a “low frequency notification sound” having a lower frequency than the “high frequency notification sound” and having the “high frequency notification sound” as harmonic overtone;
Consists of.

The “high-frequency notification sound” in this embodiment will be specifically described.
The “high-frequency notification sound” is selected from frequencies of 3 kHz or more and 7 kHz or less that are easily attached to the human ear, and 4 kHz is adopted in this embodiment.

The “low frequency notification sound” in this embodiment will be specifically described.
The “low frequency notification sound” includes at least half the frequency of the “high frequency notification sound”.
Specifically, in this embodiment in which the “high frequency notification sound” is 4 kHz, the “low frequency notification sound” includes at least 2 kHz, which is half of 4 kHz (“high frequency notification sound”).

  Further, the “low frequency notification sound” includes a frequency lower than at least 1 kHz. Specifically, in this embodiment in which the “high frequency notification sound” is 4 kHz, the “low frequency notification sound” includes at least 500 Hz.

Furthermore, the “low frequency notification sound” is composed of three or more frequencies that are “continuous as a harmonic relationship”.
As a specific example,
When the frequency of the “high frequency notification sound” is A,
The frequency of the “low frequency notification sound” is A × (1/2) ⁿ ,
And it is comprised by the continuous integer of n = 1-3.
That is, in the case of this embodiment where the “high frequency notification sound” is 4 kHz,
"Low frequency notification sound"
4 kHz × (1/2) ¹ = 2 kHz
4 kHz × (1/2) ² = 1 kHz,
4 kHz × (1/2) ³ = 500 Hz
It is comprised by these three.

Thus, the notification sound signal generator 5 of this embodiment is
As a frequency signal that makes a notification sound,
4 kHz (an example of “high-frequency notification sound”: a frequency that is very disturbing but easy to notice),
2 kHz (an example of “low frequency notification sound”: the maximum frequency at which an elderly person can easily hear),
1 kHz (an example of “low frequency notification sound”: frequency that is most easily heard by humans),
500 Hz (an example of “low frequency notification sound”: difficult to hear but soft frequency)
Is output as a waveform signal.

Furthermore, the notification sound signal generator 5
(I) As indicated by a solid line H in FIG. 1, “high frequency notification sound (4 kHz sound)” is “intermittently generated” at regular intervals;
(Ii) As shown by solid lines L1, L2, and L3 in FIG. 1, “low frequency notification sound (2 kHz, 1 kHz, 500 Hz sound)” is provided to “generate continuously”.

Here, “intermittent intervals of high frequency notification sound (4 kHz sound) will be described.
Of the intermittent intervals of “high-frequency notification sound”,
The generation interval of “high-frequency notification sound” is A,
When B is the interval between occurrences of “high-frequency notification sound”,
“Generation interval A” and “Generation stop interval B” are set to intervals at which “high-frequency notification sound” can be heard as “intermittent sound” (interval recognized as intermittent sound).

Specific examples will be described with reference to Table 1 below.
When “Generation interval A” and “Generation stop interval B” of “High-frequency notification sound” are changed,
A test was conducted to determine whether or not a “continuous sound” could be heard.
The test results are shown in “Table 1” below.

なお、表中における数字は、１０人中において「継続音」に聞こえた人数を示すものである。
また、上記テストにおける被験者の年齢割合は、１０代が１名、２０代が４名、３０代が３名、４０代が１名、５０代が１名である。

The numbers in the table indicate the number of people who heard “continuous sound” among 10 people.
Moreover, the age ratio of the test subject in the above test is one in the teenager, four in the twenties, three in the thirties, one in the forties, and one in the fifties.

From this test result,
(I) By setting the “occurrence stop interval B” to be shorter than 100 ms, a person recognizes the “high frequency notification sound” as “continuous sound”,
(Ii) Conversely, it has been found that by setting the “occurrence stop interval B” to be longer than 100 ms, the person recognizes the “high-frequency notification sound” as the “intermittent sound”.
Therefore, in this embodiment, the “occurrence stop interval B” is set longer than 100 ms from the test result, and the “high frequency notification sound” is changed to “intermittent sound”. The “occurrence interval A” may be a length (for example, 30 ms or more) that allows the “high-frequency notification sound” to be confirmed.

  The ultrasonic amplitude modulation unit 6 includes an ultrasonic oscillator that can oscillate at an ultrasonic frequency (that is, a frequency exceeding 20 kHz: 25 kHz as an example), and a waveform signal (synthesized) output from the notification sound signal generation unit 5. Waveform signal) “voltage increase / decrease change” is modulated to “oscillation voltage amplitude change” of the ultrasonic frequency.

This (modulation of the combined waveform signal to “amplitude change of oscillation voltage”) will be described with reference to FIG.
For example, it is assumed that the combined waveform signal input to the ultrasonic amplitude modulation unit 6 is a voltage change shown in FIG. 4A (in the figure, a single frequency waveform is shown for assisting understanding, Actually, it is a composite frequency signal waveform composed of a plurality of frequencies).
On the other hand, the ultrasonic oscillator mounted on the ultrasonic amplitude modulation unit 6 is assumed to oscillate at the ultrasonic frequency shown in FIG.

Then, as shown in FIG. 4C, the ultrasonic amplitude modulation unit 6
(I) Increasing the amplitude of the voltage due to the ultrasonic vibration as the signal voltage of the synthetic frequency forming the notification sound increases,
(Ii) The amplitude of the voltage due to the ultrasonic vibration is reduced as the signal voltage of the synthetic frequency forming the notification sound is reduced.
In this way, the ultrasonic amplitude modulation unit 6 modulates the combined waveform signal input from the notification sound signal generation unit 5 to “amplitude change in oscillation voltage” of the ultrasonic frequency.

  In this embodiment, as an example of the ultrasonic amplitude modulation section 6, the change in the signal voltage of the synthesized frequency forming the notification sound is changed to “the width of the voltage magnitude” as shown in FIG. An example is shown. On the other hand, unlike FIG. 4C, the change in the signal voltage of the composite frequency forming the notification sound may be changed to “the width of the voltage generation time” using the PWM modulation technique. good.

The speaker driving unit 7 drives each piezoelectric speaker 3 based on “an ultrasonic signal (a signal output from the ultrasonic amplitude modulation unit 6) obtained by amplitude-modulating a signal having a composite frequency that forms a notification sound”. By controlling the applied voltage (charging / discharging state) of the speaker 3, “an ultrasonic wave obtained by amplitude-modulating a composite frequency signal forming a notification sound” is generated from each piezoelectric speaker 3.
As a specific example, the speaker driving unit 7 is a power amplifier (or a piezo element charging / discharging device), and the waveform signal shown in FIG. 4C is transmitted from the ultrasonic amplitude modulation unit 6 to the speaker driving unit 7. 4 gives the waveform voltage shown in FIG. 4 (c) to the ultrasonic speaker 1 and generates ultrasonic waves of the output waveform shown in FIG. 4 (c) from each piezoelectric speaker 3. .

Next, means for automatically adjusting the output level (volume) of the ultrasonic speaker 1 based on environmental noise outside the vehicle will be described.
The main unit 2 includes means for automatically adjusting the amplification degree (amplification gain) of the speaker driving unit 7 based on environmental noise. This automatic adjustment means reads environmental noise detection means 8 for detecting environmental noise outside the vehicle, and reads the sound pressure level of “high-frequency notification sound” (4 kHz) that becomes “basic sound of notification sound” from the detected environmental noise. Means 9 comprises sound pressure level varying means 10 for varying the degree of amplification of the speaker drive unit 7 based on the sound pressure level of the read “high-frequency notification sound in environmental noise (4 kHz)”.

The environmental noise detection means 8 is a means for detecting environmental noise outside the vehicle (that is, environmental noise in a target range that gives a notification sound), and is equipped with a microphone having a known structure separately from the ultrasonic speaker 1. Alternatively, one of the plurality of piezoelectric speakers 3 constituting the ultrasonic speaker 1 may be used as a substitute for the microphone.
Here, a specific example of the frequency characteristic of the environmental noise outside the vehicle detected by the environmental noise detecting means 8 is shown by a solid line A in FIG.

The reading means 9 reads the sound pressure level of “high-frequency notification sound (4 kHz) in environmental noise” from “environmental noise detected by the environmental noise detection means 8”, and amplifies the detection signal of the environmental noise detection means 8. It includes a microphone amplifier.
Specifically, when the frequency characteristic of the environmental noise detected by the environmental noise detecting means 8 is a solid line A in FIG. 5, the reading means 9 reads the sound pressure level (about 40 dB) of the environmental noise at 4 kHz.
The means for reading the sound pressure level of the “high-frequency notification sound (4 kHz) in environmental noise” may be provided so as to perform a volume analysis of “4 kHz” using a computer, or the sound pressure level of a specific frequency is detected. Alternatively, the sound pressure level of “4 kHz” may be estimated from the detected sound pressure level of the specific frequency.

  The sound pressure level varying means 10 varies the amplification degree (amplification gain) of the speaker drive unit 7 in accordance with the sound pressure level of the “high frequency notification sound in environmental noise” read by the reading means 9. Sound pressure level of “high-frequency notification sound in sound” (specifically, sound pressure level of notification sound in the target range to which the notification sound is given: in a specific example, diagonally forward of the vehicle on the sidewalk side and predetermined from the vehicle) As shown by the solid line B in FIG. 5, the sound pressure level of the notification sound at a location separated by a distance is 10 dB (predetermined sound pressure) from the sound pressure level of the “high-frequency notification sound in environmental noise” read by the reading means 9. Only one example).

In addition, in this Example, although the example which raises the amplification degree (amplification gain) of the speaker drive part 7 as the environmental noise which a noise detection sensor (microphone etc.) detects becomes large was shown,
(I) The one that increases the amplification degree of the speaker drive unit 7 as the vehicle speed detected by the vehicle speed sensor increases.
(Ii) increase the degree of amplification of the speaker drive unit 7 in accordance with the increase in the engine speed detected by the engine speed sensor;
(Iii) Alternatively, a combination of the above may be used.

[Operation of Example 1]
The operation of the vehicle presence notification device of the first embodiment will be described.
This vehicle presence notification device is operated by an operation signal given from an ECU or the like, for example.
(I) one that operates constantly during traveling of the vehicle (for example, during forward traveling);
(Ii) one that operates only when the traveling speed of the vehicle is within a predetermined speed range;
(Iii) It operates only when the vehicle is traveling and the presence of a person in the traveling direction of the vehicle is confirmed by a “person recognition system (not shown)”.

When the vehicle presence notification device operates, the ultrasonic speaker 1 emits ultrasonic waves (inaudible sound waves) obtained by amplitude-modulating the signal waveform of the notification sound, as shown in FIG.
Then, as shown in FIG. 4D, as the ultrasonic wave propagates through the air, the ultrasonic wave having a short wavelength is distorted and blunted by the viscosity of the air.
As a result, as shown in FIG. 4E, the amplitude component contained in the ultrasonic wave is self-demodulated in the air being propagated, and as a result, the ultrasonic wave is separated from the ultrasonic wave generation source (ultrasonic speaker 1). Notification sound (intermittent 4 kHz sound, continuous 2 kHz, 1 kHz, 500 Hz synthesized sound) is generated at the place.

[Effect 1 of Example 1]
As described above, the vehicle presence notification device of the first embodiment “intermittently generates” “high frequency notification sound (4 kHz)” as the notification sound.
Thus, by “intermittently generating” the “high-frequency notification sound”, the “high-frequency notification sound” can be easily noticed, and even if the generated sound pressure of the “high-frequency notification sound” is lowered, the “high-frequency notification sound” It is possible to obtain the same effect (the effect of notifying the existence of a vehicle) as “sequentially generating with loud sound”.
In this way, the vehicle presence notification device can make the notification sound noticeable with high probability without generating a “high-frequency notification sound” as a “loud sound”, and can detect a person who is far away from the vehicle (the presence of the vehicle). It is possible to avoid a problem that the “high-frequency notification sound” reaches a person who does not need to be notified.

Further, even in a situation where the notification sound is masked by the environmental noise, the “high frequency notification sound (4 kHz)” is “intermittently generated” in the notification sound, so that “intermittent high frequency notification is generated from the environmental noise”. Sound (4 kHz) "can be recognized.
For this reason, even in a situation where the notification sound is masked by the environmental noise, the notification sound can be noticed with high probability.

Furthermore, it is possible to reduce the generated sound pressure of the notification sound as the generated sound pressure of the “high frequency notification sound (4 kHz)” is decreased.
As a result, in the vehicle presence notification device, the power consumption of the “speaker driving unit 7 with the largest power consumption” can be suppressed, and as a result, the battery consumption can be suppressed, for example, to extend the travel distance of the vehicle by the electric motor. Can contribute.

[Effect 2 of Example 1]
The vehicle presence notification device of the first embodiment is used as a notification sound.
(I) Along with a 4 kHz “high frequency notification sound (intermittent sound)” that is a high frequency that is likely to be attached to a human ear (a high frequency that a person generally feels uncomfortable)
(Ii) Three “low frequency notification sounds (continuous sounds)” of 2 kHz, 1 kHz, and 500 Hz having a lower frequency than the “high frequency notification sound” and having the “high frequency notification sound” as harmonic overtones are generated.

  As described above, the “4 kHz high frequency notification sound (intermittent sound)” includes three “low frequency notification sounds (continuous sound)” of 2 kHz, 1 kHz, and 500 Hz. Notification sound including “sounds”) can be softened, and discomfort given to people can be reduced.

In addition, the frequency component forming the notification sound has a harmonic overtone relationship between “a high frequency notification sound of 4 kHz” and “three low frequency notification sounds of 2 kHz, 1 kHz, and 500 Hz”. For this reason, missing fundamentals compensate for up to 250 Hz, which does not actually exist, with the illusion, and by hearing 250 Hz through the illusion, the effect of softening the notification sound can be expected and the discomfort given to the person can be further reduced. it can.
As described above, the vehicle presence notification device according to the first embodiment can suppress discomfort given to a person and can notify the surroundings of the presence of the vehicle with high probability.

[Effect 3 of Example 1]
The vehicle presence notification apparatus according to the first embodiment includes at least half the frequency of the “high frequency notification sound” as the “low frequency notification sound”.
Specifically, the notification sound includes “2 kHz low frequency notification sound” which is half of “4 kHz high frequency notification sound”.
For this reason, even if it is an elderly person who cannot hear the "4 kHz high-frequency notification sound", the "2 kHz low-frequency notification sound" that is easily noticed by the elderly person is included in the notification sound. Can know the existence of

[Effect 4 of Example 1]
The “low frequency notification sound” included in the notification sound is composed of three or more frequencies that are continuous in a harmonic relationship.
Specifically, in the case of this embodiment in which the “high frequency notification sound” is 4 kHz, the “low frequency notification sound” is composed of three consecutive frequencies of 2 kHz, 1 kHz, and 500 Hz.
In this way, by using three or more “low frequency notification sounds” that are continuous in harmonic relation to the “high frequency notification sound”, the frequency components that do not feel unpleasant increase and the effect of missing fundamentals is enhanced. It is also possible to soften the notification sound by adding a low tone by the missing fundamental effect, and to suppress the discomfort of the notification sound.

[Effect 5 of Example 1]
Since the notification sound includes a “low frequency notification sound” of 500 Hz lower than 1 kHz, the notification sound can be more reliably softened, and the discomfort caused by the notification sound can be suppressed to a low level.

[Effect 6 of Example 1]
The vehicle presence notification device of the first embodiment emits a notification sound toward the outside of the vehicle by a parametric speaker.
By using a parametric speaker, a notification sound can be generated at a position away from the vehicle. Moreover, the parametric speaker has high directivity and can generate a notification sound only in a specific direction.
As a result, the notification sound can be generated only in a “predetermined range in which the presence of the vehicle is to be notified (specifically, a location diagonally forward of the vehicle on the sidewalk side and a predetermined distance away from the vehicle)”. . In other words, it is possible to prevent the generation of a notification sound in a range where it is not necessary to notify the presence of the vehicle, and to suppress the generation of noise.

[Effect 7 of Example 1]
The vehicle presence notification device of the first embodiment automatically adjusts the output level (volume) of the ultrasonic speaker 1 based on environmental noise outside the vehicle, and the sound pressure level of “high frequency notification sound (4 kHz) in notification sound”. Is generated 10 dB higher than the sound pressure level of the “high-frequency notification sound (4 kHz) in environmental noise” read by the reading means 9.
As a result, the sound pressure level of the “high frequency notification sound (4 kHz) included in the notification sound” does not lose to the environmental noise, and the sound pressure level of the “high frequency notification sound (4 kHz) included in the notification sound” is unnecessary. There is no problem of growing. As a result, the presence of the vehicle can be notified with a high probability by the notification sound, and the generation of noise can be suppressed.

[Effect 8 of Example 1]
The notification sound of the first embodiment is composed by synthesizing a plurality of frequencies, and each frequency is composed of overtone relations (in this embodiment, 4 kHz, 2 kHz, 1 kHz, 500 Hz). Therefore, it can be heard as a single sound (in this embodiment, a “de” sound of the average temperament scale) in the human ear.

Example 2 will be described with reference to FIG. In the following embodiments, the same reference numerals as those in the first embodiment denote the same functional objects.
In the first embodiment, an example in which “low frequency notification sound (2 kHz, 1 kHz, 500 Hz)” that softens “high frequency notification sound (4 kHz)” is “continuously generated” is shown.
In contrast, the second embodiment “intermittently generates” “low frequency notification sound (2 kHz, 1 kHz, 500 Hz)”.

Specifically, the “low frequency notification sound (2 kHz, 1 kHz, 500 Hz)” of this embodiment is intermittent at the same time as the “high frequency notification sound (4 kHz)” as shown in FIG.
Thus, by intermittently generating the notification sound consisting of “high frequency notification sound (4 kHz)” and “low frequency notification sound (2 kHz, 1 kHz, 500 Hz)”, “the loudspeaker drive unit with the largest power consumption” in the vehicle presence notification device 7 ”can be halved, and as a result, the power consumption of the vehicle presence notification device can be greatly reduced.
As a result, battery consumption is suppressed, and it is possible to contribute to extending the travel distance of the vehicle by the electric motor.

In the second embodiment, an example in which “low frequency notification sound (2 kHz, 1 kHz, 500 Hz)” is interrupted simultaneously with (i) “high frequency notification sound (4 kHz)” is shown (see FIG. 6).
(Ii) The “high frequency notification sound (4 kHz)” may be intermittent at the timing opposite to the intermittent operation,
(Iii) The “high frequency notification sound (4 kHz)” may be intermittent at a timing unrelated to the intermittent operation.

A third embodiment will be described.
In the first embodiment, only one “high-frequency notification sound (4 kHz)” and a plurality of “low-frequency notification sounds (2 kHz, 1 kHz, 500 Hz)” having the “high-frequency notification sound (4 kHz)” as overtone relations are used. An example is shown in which a notification sound that forms a single tone of the average temperament scale is shown.
On the other hand, the third embodiment uses a plurality of “high frequency notification sounds” having different frequencies and a plurality of “low frequency notification sounds” each having a harmonic relationship with the plurality of “high frequency notification sounds”. It constitutes.

Specifically, in the third embodiment, a plurality of “high-frequency notification sounds” constitute a chord relationship (average temperament dominos, referers, misosi, radomis, silefas, etc .: may be long or short harmonics). Is to be selected.
A specific example is shown. When a plurality of “high-frequency notification sounds” constitute a chord relationship of “Domiso”, the “high-frequency notification sounds” are played as “high-frequency notification sounds” so that the “high-frequency notification sounds” play “Domiso”. , 6 kHz (So) is selected.

And in this Example 3,
(I) When 4 kHz (do) is set as “high frequency notification sound”, 2 kHz, 1 kHz, and 500 Hz are selected as a plurality of “low frequency notification sounds”.
(Ii) When 5 kHz (mi) is set as a “high frequency notification sound”, 2.5 kHz, 1.25 kHz, and 625 Hz are selected as a plurality of “low frequency notification sounds”.
(Iii) When 6 kHz (So) is set as a “high frequency notification sound”, 3 kHz, 1.5 kHz, and 750 Hz are selected as a plurality of “low frequency notification sounds”.

That is, in this Example 3, the notification sound is
(I) “4 kHz, 2 kHz, 1 kHz, 500 Hz” that makes a sound of
(Ii) “5 kHz, 2.5 kHz, 1.25 kHz, 625 Hz” which forms a sound of Mi,
(Iii) “6 kHz, 3 kHz, 1.5 kHz, 750 Hz” which forms the sound of Seo,
Are composed of frequencies synthesized.

  In the third embodiment, a notification generated by the vehicle is generated by generating a “chord (a tone that a person feels preferable)” as “a notification sound that suppresses discomfort and informs the existence of the vehicle with high probability”. Sound discomfort can be reduced.

In the above embodiment, the notification sound is generated forward of the vehicle when the vehicle is traveling forward. However, the notification sound may be generated behind and around the vehicle when the vehicle is traveling backward.
In the above embodiment, the parametric speaker technology is used to generate the notification sound at a place away from the vehicle. However, the notification sound is directly generated from an audible sound generator (for example, a dynamic speaker) mounted on the vehicle. It may be generated. Alternatively, a parametric speaker technique and a technique for directly emitting a notification sound (audible sound) from an audible sound generator (such as a dynamic speaker) may be combined and switched depending on the situation.

  In the above embodiment, the “high frequency notification sound” and the “low frequency notification sound” are continuous in a harmonic relationship (specifically, “4 kHz, 2 kHz, 1 kHz, 500 Hz” are continuous in a harmonic relationship). ”So that the“ high frequency notification sound ”and the“ low frequency notification sound ”maintain the overtone relationship and lack continuity (specifically,“ 4 kHz, 1 kHz, 500 Hz ”, or“ 4 kHz, 2 kHz , 500 Hz "so that overtone-related frequencies in the middle can be eliminated).

In the above-described embodiment, an example in which the notification sound is configured by “only the high-frequency notification sound and the low-frequency notification sound” is shown. However, other sounds (for example, pseudo engine sound, simulation sound, etc.) running sound, etc.) but it may also be caused by mixing.

DESCRIPTION OF SYMBOLS 1 Ultrasonic speaker 5 Notification sound signal generation part 6 Ultrasonic amplitude modulation part 7 Speaker drive part 8 Environmental noise detection means 9 Reading means 10 Sound pressure level variable means

Claims (9)

In the vehicle presence notification device that generates a notification sound outside the vehicle to notify the presence of the vehicle,
This vehicle presence notification device includes a high-frequency notification sound having a high frequency that is easily attached to a human ear as a notification sound, and a low-frequency notification sound having a lower frequency than the high-frequency notification sound and having the high-frequency notification sound as a harmonic overtone. The vehicle presence notification device is characterized by intermittently generating the high frequency notification sound in a frequency range of 3 kHz or more and 7 kHz or less of overtones . The vehicle presence notification device according to claim 1 ,
The vehicle presence notification device, wherein the low frequency notification sound is continuously generated. The vehicle presence notification device according to claim 1 ,
The vehicle presence notification device, wherein the low frequency notification sound is generated intermittently. In the vehicle presence notification device according to any one of claims 1 to 3 ,
The vehicle presence notification device, wherein the low frequency notification sound includes a half frequency of the high frequency notification sound. In the vehicle presence notification device according to any one of claims 1 to 4 ,
The low frequency notification sound is composed of a plurality of frequencies having a harmonic relationship, and the vehicle presence notification device is characterized. In the vehicle presence notification device according to any one of claims 1 to 5 ,
The vehicle presence notification device, wherein the low frequency notification sound includes a frequency lower than 1 kHz. In the vehicle presence notification device according to any one of claims 1 to 6 ,
This vehicle presence notification device releases a notification sound toward the outside of a vehicle by a parametric speaker. The vehicle presence notification device according to claim 7 ,
The parametric speaker is
An ultrasonic speaker (1) capable of generating ultrasonic waves;
A notification sound signal generator (5) for generating a frequency signal for generating a notification sound;
An ultrasonic amplitude modulation section (6) for modulating the frequency signal generated by the notification sound signal generation section (5) into an amplitude change of a voltage or current oscillated at an ultrasonic frequency;
A speaker driving unit (7) for driving the ultrasonic speaker (1) with an amplitude signal of an ultrasonic frequency amplitude-modulated by the ultrasonic amplitude modulating unit (6);
A vehicle presence notification device comprising: In the vehicle presence notification device according to any one of claims 1 to 8 ,
This vehicle presence notification device
Environmental noise detection means (8) for detecting environmental noise outside the vehicle;
Reading means (9) for reading the sound pressure level of the high-frequency notification sound in the environmental noise detected by the environmental noise detection means (8);
A sound pressure level variable means (10) for generating a sound pressure level of the high-frequency notification sound in the notification sound by a predetermined sound pressure higher than a sound pressure level of the high-frequency notification sound in the environmental noise read by the reading means (9). When,
A vehicle presence notification device comprising:

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