JP5012959B2 - Vehicle presence notification device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To generate a false engine sound close to a real engine sound without need of mounting a large dynamic speaker such as a woofer in a vehicle and by suppressing the shortage of a low-pitched sound in a short range as a problem of a parametric speaker. <P>SOLUTION: A vehicular horn 4 of an existing electromagnetic type is used as a dynamic speaker so as to generate a false engine sound from the vehicular horn 4. The shortage of a low-pitched sound in a parametric speaker 1 is complemented with a false engine sound which the vehicular horn 4 generates. Thereby, without need of mounting a large dynamic speaker such as a woofer in a vehicle, a false engine sound can be generated which is close to a real engine sound. In addition, as the vehicle approaches a pedestrian, a sound tone of the false engine sound which the pedestrian hears changes, enabling the pedestrian to easily notice the approach of the vehicle. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

The present invention relates to a vehicle presence notification device that notifies the presence of a vehicle to the surroundings by a pseudo engine sound resembling an actual engine sound (hereinafter referred to as an actual engine sound), and in particular, an electric vehicle, a fuel cell vehicle, a hybrid vehicle, and the like. The present invention relates to a technique suitable for use in a vehicle capable of traveling by an electric motor that generates rotational power when energized.
The “vehicle horn” in the present invention is a “general term for an alarm device (horn) that is mounted on a vehicle and generates an alarm sound”, and does not have a “horn member (a trumpet member whose origin is a square flute)”. It includes a vehicle alarm.

Vehicles with low vehicle running noise, such as vehicles that run on electric motors, have the problem that pedestrians are less likely to notice the vehicle.
Therefore, a proposal has been made to generate a “pseudo engine sound” from a dynamic speaker (speaker that directly emits audible sound) attached to the vehicle to the outside of the vehicle to notify the existence of the vehicle around the vehicle (for example, Patent Document 1).

The frequency range peculiar to the actual engine sound is a range of about 250 Hz to 4 kHz.
For this reason, when attempting to resemble the simulated engine sound to the actual engine sound (actual engine sound), the range of about 250 Hz to 4 kHz of the simulated engine sound should be matched to a frequency level substantially equivalent to the actual engine sound. Is required.

Therefore, it is conceivable to generate a pseudo engine sound having a frequency level substantially equal to that of the actual engine sound using a dynamic speaker. In that case, in order to reproduce a low-frequency range of 800 Hz or less of the pseudo engine sound, it is conceivable to mount a “dynamic speaker using a large cone type diaphragm such as a woofer” on the vehicle.
However, when (A1) “dynamic speaker using a large cone-shaped diaphragm” is mounted on a vehicle, it becomes difficult to mount the vehicle on the vehicle, and problems such as an increase in vehicle weight and cost increase occur. End up.

On the other hand, instead of a technique using a dynamic speaker, a technique has been proposed (not a well-known technique) in which a pseudo engine sound is generated outside a vehicle using a parametric speaker to notify the presence of the vehicle.
The technology for generating the pseudo engine sound by the parametric speaker is to “modulate the pseudo engine sound waveform signal” and emit it from the ultrasonic speaker. The ultrasonic wave emitted from the ultrasonic speaker (the sound wave that cannot be heard by the ear). ) Is self-demodulated in the air in the middle of propagation to generate a pseudo engine sound at a location away from the vehicle.

As described above, in the case of a parametric speaker, it is possible to radiate an ultrasonic wave and generate a low tone by using an amplitude component included in the ultrasonic wave.
For this reason, the problem (A1) can be avoided by using a parametric speaker.

However, the low-frequency sound reproduced by the parametric speaker has a delay in self-demodulation in the air due to its long wavelength, and unlike the low-frequency sound reproduced by the dynamic speaker, directivity (sound straightness) ) Is strong.
For this reason, in the range close to the ultrasonic speaker (A2), the sound pressure of the frequency sensed by the person decreases as shown by the solid line A in FIG. 12 due to the influence of the direction of the person's outer ear (ear hole). It will fall according to.

Note that a solid line A in FIG. 12 shows a state in which the sound detection unit of the microphone is set at the back of the dummy outer ear in the dummy head (similar to a human head) and the reproduced sound from the parametric speaker is detected. It is a frequency characteristic.
A broken line B in FIG. 12 is a frequency characteristic for comparison, and is a frequency characteristic when a reproduction sound from a parametric speaker is directly detected by a microphone without using a dummy head.
As is clear from comparison between the solid line A and the broken line B, the low-frequency sound pressure perceived by a person decreases as the frequency decreases in the low sound range due to the influence of the outer ear.

  As described above, in the case of using a parametric speaker, due to the above (A2), in the range close to the vehicle, the low level of the pseudo engine sound reproduced by the parametric speaker occurs, and as a result, the pseudo engine sound by the parametric speaker is This is a hindrance to matching the frequency level with the engine sound.

JP 2005-289175 A

  The present invention has been made in view of the above problems, and the purpose thereof is to mount a `` dynamic speaker using a large corn-type diaphragm similar to a woofer '' on a vehicle, which excels at low-frequency reproduction. In addition, it is an object of the present invention to provide a vehicle presence notification device capable of generating a pseudo engine sound close to a real engine sound while suppressing the “insufficiency of the pseudo engine sound in a range close to the vehicle” which is a problem of the parametric speaker.

[Means of Claim 1]
The vehicle presence notification device adopting the means of claim 1 uses an electromagnetic vehicle horn having an existing structure that generates a warning sound by applying a self-excited voltage, by using a separate excitation voltage (a voltage lower than the self-excited voltage). It is driven by an electric signal (an electric signal that makes a pseudo engine sound).
An electromagnetic vehicle horn has a movable contact that turns on and off the magnetic force generating coil below the separately-excited voltage and is in contact with the fixed contact. Therefore, an “electric signal that makes a pseudo engine sound” is given to the magnetic force generating coil. In response to the magnetic force change, the diaphragm and the movable iron core vibrate in response to “an electric signal that makes a pseudo engine sound” to generate a “pseudo engine sound”.
In other words, by providing an electromagnetic vehicle horn with an “electric signal that produces a pseudo engine sound” having a separate excitation voltage, the “electromagnetic vehicle horn can be used as a dynamic speaker”.

(First effect)
In this way, by combining the “parametric speaker” and the “vehicle horn used as a dynamic speaker”, the “insufficient bass in the range close to the vehicle” possessed by the parametric speaker can be used as a “dynamic speaker”. Can be supplemented with a "horn".
For this reason, without mounting a “dynamic speaker using a large cone-shaped diaphragm”, which excels in bass reproduction, in the vehicle, it is possible to suppress the lack of bass in the pseudo engine sound even in a range close to the vehicle. A pseudo engine sound close to the sound can be generated.

Further, since the “existing vehicle horn” is used as a means for compensating for “insufficient bass” of the parametric speaker, the cost can be reduced and the vehicle mounting property can be secured.
In particular, as shown in claim 5 to be described later, by sharing a vehicle horn that generates an alarm sound by a horn switch, it is not necessary to separately install equipment for compensating for “insufficient bass”, thereby reducing costs and mounting. Space can be secured easily.

(Second effect)
As the distance between the pedestrian and the vehicle (ultrasonic speaker) decreases, the “pseudo engine sound by the vehicle horn” increases.
Thereby, when the vehicle approaches the pedestrian, “low sound reproduced by the vehicle horn” increases, and the tone of the pseudo engine sound that can be heard by the pedestrian changes.
In this way, the low frequency range of the pseudo engine sound increases as the vehicle approaches the pedestrian, and the “timbre” of the pseudo engine sound changes, so that the pedestrian can easily recognize the pseudo engine sound, and high probability. Can inform the pedestrian of the presence of the vehicle.

[Means of claim 2]
The pseudo engine sound produced by the parametric speaker is highly straight.
For this reason, when the pseudo engine sound from the parametric speaker is reflected by a reflecting object (for example, a signboard) present on the sidewalk or the like, the pseudo engine sound heard by the pedestrian is heard from a direction different from that of the vehicle. That is, erroneous recognition due to reflection of ultrasonic waves occurs.

In order to solve this problem, the vehicle presence notification apparatus according to the means of claim 2 is configured to arrange a vehicle horn and an ultrasonic speaker in a parametric speaker adjacent to each other (approaching).
In this way, by arranging the vehicle horn and the ultrasonic speaker close to each other, the range where the “region where erroneous recognition is caused by the reflection of ultrasonic waves” and the “pseudo engine sound by the vehicle horn” overlap is enlarged. Can do.
In a range where the “region where misrecognition occurs due to the reflection of ultrasonic waves” and the “pseudo engine sound by the vehicle horn” overlap, the “pseudo engine sound by the vehicle horn” is also heard by the pedestrian, so the reflection of the ultrasonic wave Can prevent false recognition.

[Means of claim 3]
The vehicle presence notification apparatus according to claim 3 includes ultrasonic directivity expanding means for expanding the directivity of the ultrasonic wave generated by the ultrasonic speaker when the vehicle traveling speed is equal to or lower than a predetermined speed (during low-speed traveling). Is.
Thereby, a pseudo engine sound can be generated for a wide range of pedestrians, and the vehicle notification range during low-speed traveling can be expanded.

[Means of claim 4]
The vehicle presence notification device according to claim 4 is a vehicle horn for the purpose of widening the reach of the “pseudo engine sound by the vehicle horn” when the ultrasonic directivity extending means widens the directivity of the ultrasonic speaker. This increases the sound pressure of the pseudo engine sound that occurs.
Accordingly, it is possible to increase a range where the “region where erroneous recognition is caused by reflection of ultrasonic waves” expanded by the means of claim 3 and the “pseudo engine sound by the vehicle horn” overlap, and the expanded ultrasonic waves It is possible to suppress misrecognition due to reflection.

[Means of claim 5]
The vehicle horn in the vehicle presence notification device according to the means of claim 5 is such that a self-excited voltage is applied and an alarm sound is generated when a horn switch operated by a vehicle occupant is turned on.
Thus, by sharing the “vehicle horn that generates alarm sound” and the “vehicle horn that generates pseudo engine sound”, the cost of the vehicle presence notification device can be reduced, and the pseudo engine sound can be reduced. It is possible to easily secure a mounting space for the generated vehicle horn.

It is a schematic block diagram of a vehicle presence alerting | reporting apparatus. It is sectional drawing which shows a specific example of the horn for vehicles. It is a graph which shows the frequency characteristic at the time of operating the horn for vehicles by self-excitation, and when operating by separate excitation. It is the front view and top view of an ultrasonic speaker. It is explanatory drawing which shows the arrival distribution of a pseudo | simulation engine sound. It is explanatory drawing of a pseudo | simulation engine sound. It is a principle explanatory view of a parametric speaker. It is a graph which shows the frequency characteristic of the real engine sound, the pseudo engine sound by a cone type dynamic speaker, the pseudo engine sound by a parametric speaker, and the pseudo engine sound by the vehicle horn by a parametric speaker and other excitation. It is a graph which shows the frequency characteristic of the pseudo engine sound by the difference in the distance of a pedestrian and a vehicle. Explanatory diagram showing "reaching area of pseudo engine sound by parametric speaker" and "area where erroneous recognition occurs due to reflection of ultrasonic waves", and "area where erroneous recognition occurs due to reflection of ultrasonic waves" and "pseudo engine due to vehicle horn" It is explanatory drawing which shows a "sound reaching area." Explanatory drawing showing "reaching area of pseudo engine sound by parametric speaker at low speed", "reaching area of pseudo engine sound by vehicle horn at low speed" and "area where erroneous recognition occurs due to reflection of ultrasonic wave at low speed" It is. It is a graph which shows the frequency characteristic explaining that the low frequency range of a parametric speaker falls by the influence of an outer ear.

An embodiment for implementing a vehicle presence notification device will be described with reference to the drawings.
The vehicle presence notification device generates a pseudo engine sound toward the outside of the vehicle to notify the surroundings of the vehicle S of the presence of the vehicle S, and directs an ultrasonic wave obtained by ultrasonically modulating the pseudo engine sound to the outside of the vehicle. A parametric speaker 1 is provided.
Further, the vehicle presence notification device is provided with a self-excited voltage (for example, 8 V or more) that is greater than or equal to a threshold value with direct current, and thus the magnetic core 2 vibrates and the movable iron core 2 vibrates, and the vibration coupled to the movable iron core 2 occurs. The vehicle horn 4 that generates an alarm sound when the plate 3 vibrates together with the movable iron core 2 is used. A pseudo engine sound is also generated from the vehicle horn 4 by giving an electric signal that makes a sound.

Next, a specific example of the vehicle presence notification device will be described with reference to FIGS. In the first embodiment, the same reference numerals as those in the “Mode for Carrying Out the Invention” denote the same functional objects.
[Configuration of Example 1]
As shown in FIG. 1, the vehicle presence notification device of the first embodiment includes an electromagnetic vehicle horn 4 having an existing structure, an ultrasonic speaker 5 capable of emitting ultrasonic waves, a vehicle horn 4 and ultrasonic waves. And a main body device 6 for controlling the operation of the speaker 5.

(Description of vehicle horn 4)
The vehicle horn 4 is an electromagnetic alarm sound generator having a known structure that generates an alarm sound toward the outside of the vehicle, and is mounted on, for example, the front portion of the vehicle S so as to emit the alarm sound toward the outside of the vehicle. Is.
A specific example of the vehicle horn 4 will be described with reference to FIG.

The vehicle horn 4 is attached to the vehicle S via the stay 11,
A coil 12 that generates a magnetic force when energized;
A fixed iron core (magnetic attraction core) 13 that generates a magnetic attraction force by the magnetic force generated by the coil 12, and
A movable iron core (movable core) 2 supported at the center of the diaphragm (diaphragm) 3 and supported so as to be movable toward the fixed iron core 13;
In conjunction with the movement of the movable iron core 2, the movable iron core 2 moves toward the fixed iron core 13, thereby moving away from the fixed contact 14 and interrupting the energization of the coil 12,
Is provided.

And, by applying a self-excited voltage (voltage of 8 V or more) equal to or higher than a threshold value to the energization terminal of the vehicle horn 4,
(I) A suction operation in which the movable iron core 2 is magnetically attracted to the fixed iron core 13 by energization of the coil 12;
(Ii) a restoring operation in which the movable contact 15 is separated from the fixed contact 14 by this suction operation, the energization of the coil 12 is stopped, and the movable iron core 2 and the movable contact 15 are restored;
Repeat continuously.

As described above, when the energization of the coil 12 is interrupted (interruption of generation of the magnetic attractive force of the fixed iron core 13), the diaphragm 3 and the diaphragm 3 vibrate, so that the vehicle horn 4 generates an alarm sound. .
The vehicle horn 4 is often set so that the fundamental frequency of the alarm sound is a low frequency around 400 Hz, and can generate a low frequency even if it is small.
A solid line A in FIG. 3 shows a frequency characteristic of an alarm sound generated by the vehicle horn 4 (an operating sound when a self-excited voltage is applied). As is clear from the solid line A in FIG. 3, the alarm sound generated by the vehicle horn 4 (the operation sound when a self-excited voltage is applied) is set at the fundamental frequency (the ON-OFF interval of the movable contact 15). Frequency) and its harmonic frequency.

2A is reinforced by a horn member 16 (in the drawing, a spiral trumpet member) 16 due to vibration of the diaphragm 3, and is released to the outside of the vehicle. Further, the vehicle horn 4 of FIG. 2B resonates the resonance plate 17 with an alarm sound due to the vibration of the diaphragm 3, and emits an alarm sound enhanced by the resonance sound to the outside of the vehicle.
Hereinafter, as a specific example, the embodiment will be described using the vehicle horn 4 including the horn member 16 (trumpet member), but the embodiment is not limited thereto.

(Description of ultrasonic speaker 5)
Similar to the vehicle horn 4 described above, the ultrasonic speaker 5 is attached to, for example, the front portion of the vehicle S so as to emit generated ultrasonic waves toward the front of the vehicle S. 4 is attached at a position adjacent to (approaching) 4.

A specific structural example of the ultrasonic speaker 5 is shown in FIG. In addition, the structure of the ultrasonic speaker 5 shown in FIG. 4 is an example, Comprising: It is not limited.
The ultrasonic speaker 5 is an ultrasonic generator that generates air vibration having a frequency (20 kHz or higher) higher than the human audible band.
The ultrasonic speaker 5 of this embodiment is a speaker array in which a plurality of piezoelectric speakers (ceramic speakers, piezo speakers, etc.) 21 suitable for ultrasonic reproduction are arranged. In addition, the piezoelectric speaker 21 used in this embodiment includes a piezo element that expands and contracts according to an applied voltage (charge / discharge) and a diaphragm 3 that vibrates air by the expansion and contraction of the piezo element. Of structure.

The ultrasonic speaker 5 can control the amount of ultrasonic energy generated and the directivity range of the ultrasonic wave emitted from the piezoelectric speaker 21 depending on the number and arrangement of the piezoelectric speakers 21 to be used. Moreover, the directivity range of an ultrasonic wave can be controlled also by using the directivity control member (horn member) 22 shown in FIG.
In this embodiment, an example in which the piezoelectric speaker 21 is used as an example of a speaker that generates ultrasonic waves is shown. However, this is only an example and is not limited. The ultrasonic wave generation means may be used.

Here, in FIG. 5A, the reach range α of the pseudo engine sound by the parametric speaker 1 is shown, and in FIG. 5B, the reach range β of the pseudo engine sound by the vehicle horn 4 is shown. FIG. 5 shows a range where the sound pressure of the pseudo engine sound is 50 dB.
As described above, the ultrasonic speaker 5 of the first embodiment is provided so as to radiate ultrasonic waves toward the front of the vehicle S.
Further, the vehicle horn 4 is provided so that the pseudo engine sound reaches the periphery of the vehicle horn 4 evenly when the vehicle S is viewed from above. As a specific example, the opening of the horn member 16 in the vehicle horn 4 is attached so as to be directed downward (in the direction toward the road surface) of the vehicle S. The direction of the opening of the horn member 16 is not limited.

(Description of the main unit 6)
Next, the main body device 6 that generates a pseudo engine sound from the vehicle horn 4 and the ultrasonic speaker 5 will be described. In addition, the structure of the main body apparatus 6 demonstrated below is an example, and is not limited.
The main unit 6 is
(A) a pseudo engine sound creating unit 23 that creates a frequency signal that forms a pseudo engine sound;
(B) an ultrasonic amplitude modulation unit 24 that modulates the frequency signal of the pseudo engine sound into an ultrasonic frequency;
(C) an ultrasonic speaker amplifier 25 for driving the ultrasonic speaker 5 with a modulated ultrasonic frequency;
(D) A horn drive amplifier 26 (power amplifier) that drives the vehicle horn 4 with a frequency signal of the pseudo engine sound (an electrical signal that forms the pseudo engine sound) is provided.
The main unit 6 operates by receiving an operation signal (pseudo engine sound generation instruction signal) from, for example, an ECU (abbreviation of engine control unit).

The main unit 6 is also equipped with a power supply unit (not shown) that is connected to an in-vehicle power source such as an in-vehicle battery and supplies power necessary for the operation of each circuit (electrical functional component) mounted on the main unit 6. To do.
The main unit 6 is equipped with other functions such as means (not shown) for automatically adjusting the output level (volume) of the vehicle horn 4 and the ultrasonic speaker 5 based on the environmental noise of the vehicle S or the vehicle speed. It may be a thing.

Hereinafter, the means (a) to (d) mounted on the main unit 6 will be described.
(Description of the pseudo engine sound creation unit 23)
The pseudo engine sound creating unit 23 is configured by a computer having a well-known structure including a CPU that performs arithmetic processing, storage means (memory) that stores a program, an input circuit, an output circuit, and the like. The storage means stores an engine sound generation program (acoustic software) for creating “an electric signal that makes a pseudo engine sound” by digital technology.

An example of the engine sound generation program will be described. The engine sound generation program described below is a specific example and is not limited.
The engine sound generation program of this embodiment creates a frequency signal (waveform signal) that forms a pseudo engine sound based on a clock signal generated by a reference clock (crystal oscillator) mounted on a computer,
(I) A predetermined frequency (for example, a selected frequency selected from 1 Hz to 10 Hz) is “AHz”,
(Ii) A pseudo engine sound is generated by simultaneously generating a number of continuous frequency signals at intervals of “AHz”.

As a specific example, this embodiment shows an example in which a fixed frequency of “4 Hz” is used as “AHz”. Note that “4 Hz” is a specific example, and for example, “8 Hz” that is twice as much may be used. Alternatively, a fixed frequency including a decimal point (for example, a frequency selected from “3.5 Hz to 4.5 Hz” or “7.5 Hz to 8.5 Hz”) may be used.
Further, in this embodiment, the frequency signal forming the pseudo engine sound is composed of a large number of frequency signals continuous at intervals of “AHz (4 Hz)” as described above. A part of the frequency signal may be partially thinned out. That is, the frequency signal at intervals of 4 Hz may be partially absent.

On the other hand, in the engine sound generation program, “frequency range specifying means (program) for generating“ a large number of continuous frequency signals (frequency signals forming a pseudo engine sound) ”at intervals of 4 Hz“ only within a predetermined frequency range ”. Is provided.
Here, an example of selecting the “predetermined frequency range” will be described.
When the frequency characteristic of the actual engine sound shows the characteristic of the solid line E in FIG. 6A, the frequency range of the engine sound that can be heard by the human ear is from “maximum sound pressure to −10 dB lower than the sound pressure”. A sound that is “main frequency L (frequency range within Δ10 dB)” and deviates from “main frequency L” (sound with low sound pressure) is masked by sound of “main frequency L” and is hardly recognized.

  Therefore, the engine sound generation program utilizes the fact that only the “major frequency L” of the engine sound can be heard by the human ear, and as shown in FIG. The “frequency signal (frequency signal forming the pseudo engine sound)” is generated with “only the main frequency L”.

This will be specifically described.
When the simulated engine sound is made to resemble the “real engine sound of a specific vehicle type”, the “real engine sound of a specific vehicle type” is measured.
The “frequency range from the maximum sound pressure to the sound pressure reduced by −10 dB” in the engine sound is measured. This measurement range is the “main frequency L” described above. The main frequency L substantially matches the frequency range (about 250 Hz to 4 kHz) with high human sound sensitivity. For this reason, as shown in FIG. 6B, the engine sound generation program is provided so as to generate the “frequency signal forming the pseudo engine sound” only at “250 Hz to 4 kHz (main frequency L)”. .

  Further, the engine sound generation program is provided with a frequency characteristic processing means (program) for processing (characterizing) the frequency characteristics of “a large number of frequency signals continuous at intervals of 4 Hz (frequency signals forming a pseudo engine sound)”. It has been.

When the simulated engine sound is made to resemble the “actual engine sound of a specific vehicle type”, it is assumed that the frequency characteristic of the engine sound of the specific vehicle type shows the characteristic indicated by the solid line E in FIG.
In that case, the frequency characteristics of the “frequency signal forming the pseudo engine sound” (the sound pressure levels of a number of frequency signals are set so as to match the frequency characteristics of the specific vehicle type {characteristic of the solid line E in FIG. 6A)}. (Characteristic to be drawn) is processed into a frequency characteristic indicated by a broken line E in FIG.

(Description of Ultrasonic Amplitude Modulator 24)
The ultrasonic amplitude modulation unit 24 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 (pseudo) output from the pseudo engine sound creation unit 23. The “voltage increase / decrease change” of the electrical signal (engine signal) is modulated to the “frequency change of the oscillation voltage” of the ultrasonic frequency.
In this embodiment, an example in which the ultrasonic amplitude modulation unit 24 is provided independently is provided to assist understanding. However, the function of the ultrasonic amplitude modulation unit 24 may be included in the above-described computer program.

Ultrasonic modulation by the ultrasonic amplitude modulation unit 24 (modulation of “frequency signal forming pseudo engine sound” to “amplitude change of oscillation voltage”) will be described with reference to FIG.
For example, it is assumed that the “frequency signal forming the pseudo engine sound” input to the ultrasonic amplitude modulation unit 24 is a voltage change shown in FIG. 7A (in the figure, a single frequency is used for assisting understanding). This is actually a signal waveform with a synthetic frequency of 4 Hz intervals).
On the other hand, the ultrasonic oscillator mounted on the ultrasonic amplitude modulator 24 is assumed to oscillate at the ultrasonic frequency shown in FIG.

Then, as shown in FIG. 7C, the ultrasonic amplitude modulation unit 24
(I) Increasing the amplitude of the voltage due to ultrasonic vibration as the signal voltage of the frequency forming the pseudo engine sound increases,
(Ii) The amplitude of the voltage due to ultrasonic vibration is reduced as the signal voltage of the frequency forming the pseudo engine sound is reduced.
In this way, the ultrasonic amplitude modulation unit 24 modulates the “frequency signal forming the pseudo engine sound” input from the pseudo engine sound creation unit 23 to “amplitude change in oscillation voltage” of the ultrasonic frequency. is there.

  In this embodiment, as an example of the ultrasonic amplitude modulation unit 24, the change in the signal voltage of the frequency forming the pseudo engine sound is changed to “the width of the voltage magnitude” as shown in FIG. 7C. An example is shown. In contrast to this, unlike FIG. 7 (c), the change in the signal voltage of the frequency forming the pseudo engine sound may be changed to the “voltage generation time width” using the PWM modulation technique. good.

(Description of the ultrasonic speaker amplifier 25)
The ultrasonic speaker amplifier 25 drives each piezoelectric speaker 21 based on “an ultrasonic signal obtained by amplitude-modulating a frequency signal forming a pseudo engine sound (an output signal from the ultrasonic amplitude modulation unit 24)”. By controlling the applied voltage (charging / discharging state) of the speaker 21, “an ultrasonic wave obtained by amplitude-modulating a frequency signal that forms a pseudo engine sound” is generated from each piezoelectric speaker 21.
As a specific example, the ultrasonic speaker amplifier 25 is a charge switching circuit (or a charge / discharge circuit of a piezo element) that can be applied to each piezoelectric speaker 21 by switching a positive voltage or a negative voltage. When the waveform signal shown in FIG. 7C is given from the amplitude modulation unit 24 to the ultrasonic speaker amplifier 25, the ultrasonic speaker amplifier 25 gives the waveform voltage shown in FIG. An ultrasonic wave having an output waveform shown in FIG. 7C is generated from the piezoelectric speaker 21.

(Description of Horn Drive Amplifier 26)
The horn drive amplifier 26 is a power amplifier (power amplification circuit) for operating the vehicle horn 4 as a dynamic speaker, and the waveform signal (electric signal forming the pseudo engine sound) output from the pseudo engine sound creating unit 23 is “ The voltage increase / decrease change is amplified and applied to the energization terminals of the vehicle horn 4 (terminals connected to both ends of the coil 12).
The maximum output of the horn drive amplifier 26 (maximum output for generating a pseudo engine sound) is limited to less than 8V (another excitation voltage), and the vehicle horn is generated by the voltage output for generating the pseudo engine sound. 4 is provided so as not to generate an alarm sound.

[Operation of Example 1]
The operation of the vehicle presence notification device of the first embodiment will be described.
As described above, this vehicle presence notification device operates by being given an operation signal from, for example, an ECU.
(I) one that operates constantly during traveling of the vehicle S (for example, during forward traveling);
(Ii) one that operates only when the traveling speed of the vehicle S 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 S is confirmed by a “person recognition system (not shown)”.

When the vehicle presence notification device operates, the ultrasonic speaker 5 emits ultrasonic waves (inaudible sound waves) obtained by amplitude-modulating the signal waveform of the pseudo engine sound, as shown in FIG.
Then, as shown in FIG. 7D, as the ultrasonic wave propagates in 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. 7E, the amplitude component contained in the ultrasonic wave is self-demodulated in the air being propagated, and as a result, the ultrasonic wave generation source (the vehicle on which the ultrasonic speaker 5 is mounted). A pseudo engine sound is generated at a location away from S).

In addition, when the vehicle presence notification device is activated, an electric signal based on a separately excited voltage is generated to cause the vehicle horn 4 to generate a pseudo engine sound.
In the electromagnetic vehicle horn 4, the movable contact 15 is in contact with the fixed contact 14 and the coil 12 is energized at a voltage lower than the separate excitation voltage. For this reason, when an “electric signal that makes a pseudo engine sound” is applied to the coil 12 of the vehicle horn 4, a magnetic force change occurs according to the “electric signal that makes a pseudo engine sound”, and the movable iron core 2 and the diaphragm 3 Vibrates in response to “an electrical signal that makes a simulated engine sound”.
In this manner, the electromagnetic vehicle horn 4 can be used as a dynamic speaker, and a pseudo engine sound can be generated from the vehicle horn 4.

A frequency characteristic of the vehicle horn 4 when the vehicle horn 4 is used as a dynamic speaker is shown by a broken line B in FIG. This broken line B is a frequency characteristic when a 1 V sine wave sweep signal (a variable signal from a low frequency to a high frequency) is applied to the vehicle horn 4.
As is apparent from the broken line B in FIG. 3, the vehicle horn 4 can be used as a dynamic speaker and a low frequency range of 800 Hz or less can be reproduced. In particular, it can be seen that the reproduction capability of low frequencies around 300 Hz and 500 Hz is large.

[Effect 1 of Example 1]
As described above, the vehicle presence notification device according to the first embodiment combines the “parametric speaker 1” and the “vehicle horn 4 used as a dynamic speaker”, so that the “range close to the vehicle S” held by the parametric speaker 1 is achieved. Can be compensated by the “vehicle horn 4 used as a dynamic speaker”.

This will be specifically described with reference to FIG.
Each characteristic in FIG. 8 is a frequency characteristic measured using a dummy head at a distance of 1 m from the sound source.
The solid line A in FIG. 8 shows the frequency characteristics of the real engine sound,
The dashed-dotted line B in FIG. 8 indicates the frequency of the “cone-type dynamic speaker (a small speaker having a cone diameter of 10 cm in consideration of the mountability in a vehicle)” that reproduces the simulated engine sound created by the simulated engine sound creation unit 23. Show the characteristics,
A broken line C in FIG. 8 indicates the frequency characteristic of the “parametric speaker 1” that reproduces the simulated engine sound created by the simulated engine sound creation unit 23.
A two-dot chain line D in FIG. 8 shows frequency characteristics of the “parametric speaker 1 and the vehicle horn 4 by separate excitation” that reproduces the pseudo engine sound created by the pseudo engine sound creation unit 23.

As is clear by comparing the solid line A and the one-dot chain line B in FIG. 8, the “cone-type dynamic speaker (small speaker with a cone diameter of 10 cm)” is not good at reproduction of 2 kHz or less, and the pseudo engine sound is in the middle range. And it becomes insufficient in the low frequency range.
Here, in the case of using a “dynamic speaker using a large cone-shaped diaphragm 3 such as a woofer” in order to increase the reproduction capability in the middle sound range and the low sound range, it is difficult to increase the cost, increase the weight, and secure the mounting space. Become.

Further, as is clear from comparison between the solid line A and the broken line C in FIG. 8, the pseudo engine sound generated by the “parametric speaker 1” has a low sound range in a state where the distance to the vehicle S (ultrasonic speaker 5) is short. I feel deficient.
As is apparent from the two-dot chain line D, “pseudo engine sound by the parametric speaker 1 whose bass range is insufficient at a short distance to the sound source” is reproduced in the “pseudo engine sound by the parametric speaker 1 at a short distance to the sound source. By adding the “pseudo engine sound by the vehicle horn 4”, a pseudo engine close to the real engine sound can be generated in a wide range of 250 Hz to 4 kHz.

  That is, by combining the “parametric speaker 1” and the “vehicle horn 4 used as a dynamic speaker”, the “insufficient bass in the range close to the vehicle S” possessed by the parametric speaker 1 is used as a “dynamic speaker”. The vehicle horn 4 "can be supplemented, and even if the distance between the vehicle S and the pedestrian is short, a pseudo engine that approximates the actual engine sound can be generated in a wide range of 250 Hz to 4 kHz.

[Effect 2 of Example 1]
In the vehicle presence notification apparatus according to the first embodiment, the “low frequency of the pseudo engine sound by the vehicle horn 4” increases as the distance between the pedestrian and the vehicle S (ultrasonic speaker 5) approaches.
Thus, when the vehicle S approaches the pedestrian, the “low sound reproduced by the vehicle horn 4” increases, and the tone of the pseudo engine sound heard by the pedestrian changes.

This will be specifically described with reference to FIG.
Each characteristic in FIG. 9 is a frequency characteristic obtained by reproducing the simulated engine sound created by the simulated engine sound creating unit 23 using both the “parametric speaker 1 and the vehicle horn 4” using a dummy head. Yes,
A solid line A in FIG. 9 shows a pseudo engine sound frequency characteristic when the distance from the sound source to the measurement unit is 2 m,
The one-dot chain line B in FIG. 9 shows the pseudo engine sound frequency characteristic when the distance from the sound source to the measurement unit is 5 m,
A two-dot chain line C in FIG. 9 indicates the pseudo engine sound frequency characteristic when the distance from the sound source to the measurement unit is 10 m.

As apparent from the comparison of the solid line A (2 m), the alternate long and short dash line B (5 m), and the alternate long and two short dashes line C (10 m), as the vehicle S (ultrasonic speaker 5) approaches the pedestrian, the “vehicle horn” The influence of “pseudo engine sound due to 4” increases, and the sound pressure in the low frequency range (especially the sound pressure near 500 Hz) increases.
As the vehicle S approaches the pedestrian in this manner, the “low sound reproduced by the vehicle horn 4” increases and the tone of the pseudo engine sound that can be heard by the pedestrian changes. Can be easily noticed, and a pedestrian can be informed of the presence of the vehicle with high probability.

[Effect 3 of Example 1]
The pseudo engine sound produced by the parametric speaker 1 is highly straight.
For this reason, as shown in FIG. 10A, in the “reaching range α of the pseudo engine sound by the parametric speaker 1”, when the ultrasonic wave is reflected by a reflector (eg, a signboard) X present on the sidewalk or the like, The pseudo engine sound that can be heard by the pedestrian H is heard from a direction different from the vehicle S (direction of the reflector X).
That is, in the range in FIG. 10A (region γ where erroneous recognition occurs due to reflection of ultrasonic waves), erroneous recognition due to reflection of ultrasonic waves occurs.

In order to solve this problem, in the first embodiment, the vehicle horn 4 and the ultrasonic speaker 5 in the parametric speaker 1 are disposed adjacent to (approaching).
In this manner, by arranging the vehicle horn 4 and the ultrasonic speaker 5 close to each other, the “region γ in which erroneous recognition is caused by reflection of ultrasonic waves” and the “region of arrival of the pseudo engine sound β by the vehicle horn 4”. The range in which and overlap can be increased.

In a range where the “region γ in which erroneous recognition is caused by the reflection of ultrasonic waves” and the “reaching region β of the pseudo engine sound by the vehicle horn 4” overlap, the “pseudo engine sound by the vehicle horn 4” is also transmitted to the pedestrian. Since it can be heard, erroneous recognition due to reflection of ultrasonic waves can be suppressed.
That is, the “region γ ′ {the portion indicated by hatching in FIG. 10B) in which erroneous recognition is substantially caused by reflection of ultrasonic waves” can be reduced, and erroneous recognition due to reflection of ultrasonic waves can be suppressed. .

[Effect 4 of Example 1]
In the vehicle presence notification device of the first embodiment, the vehicle horn 4 is used as a dynamic speaker to generate a pseudo engine sound. For this reason, the “pseudo engine sound by the vehicle horn 4” can be delivered to the “rear side of the vehicle S” where the pseudo engine sound from the parametric speaker 1 is difficult to reach. For this reason, when the vehicle S is traveling backward, a pseudo engine sound can be generated behind the vehicle S to notify the pedestrian behind the vehicle S of the presence of the vehicle S.

[Effect 5 of Example 1]
The vehicle horn 4 according to the first embodiment is provided so that a self-excited voltage is applied to generate an alarm sound when the horn switch is turned on by an occupant. That is, the vehicle horn 4 of the first embodiment shares the “vehicle horn 4 that generates an alarm sound” and the “vehicle horn 4 that generates a pseudo engine sound”.
Thus, by making the “vehicle horn 4 that generates an alarm sound” and the “vehicle horn 4 that generates a pseudo engine sound” into one, the cost of the vehicle presence notification device can be reduced, It is easy to secure a mounting space for the vehicle horn 4 that generates the pseudo engine sound.

A second embodiment 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 second embodiment, when the traveling speed of the vehicle S is equal to or lower than a predetermined speed (during low-speed traveling), the directivity of the ultrasonic wave generated by the ultrasonic speaker 5 (the directivity in the left-right direction with respect to the traveling direction of the vehicle) is widened. Ultrasonic directivity expanding means (expander) is provided.

As shown in FIG. 11, the ultrasonic directivity extending means extends the “reaching range α of the pseudo engine sound by the parametric speaker 1” compared to the first embodiment during low-speed traveling,
(I) The range of ultrasonic waves may be expanded by using a plurality of auxiliary piezoelectric speakers 21 arranged in an oblique direction on the left and right with respect to the traveling direction of the vehicle S,
(Ii) The ultrasonic radiation of the ultrasonic speaker 5 may be inclined toward the road surface by using an actuator (solenoid or the like) to spread the ultrasonic wave on the road surface,
(Iii) The acoustic lens provided in the ultrasonic radiation direction of the ultrasonic speaker 5 may be displaced by an actuator (solenoid or the like) to diffuse ultrasonic waves.
That is, the ultrasonic directivity extending means is not limited and can be changed as appropriate.

  The vehicle presence notification device according to the second embodiment can generate a pseudo engine sound for a wide range of pedestrians H by widening the “reaching range α of the pseudo engine sound by the parametric speaker 1” at a low speed. It is possible to widen the notification range of the vehicle S when traveling at low speed.

Further, in the second embodiment, when the ultrasonic directivity extending means expands the “pseudo engine sound reach range α by the parametric speaker 1”, the “pseudo engine sound reach region β by the vehicle horn 4” is expanded. Thus, the sound pressure of the pseudo engine sound generated by the vehicle horn 4 is increased.
As a result, the range in which “the region γ in which erroneous recognition occurs due to reflection of ultrasonic waves” expanded by the extension of the ultrasonic directivity at low speed and the “region of arrival β of the pseudo engine sound by the vehicle horn 4” overlap is increased. And the occurrence of erroneous recognition due to the reflection of the extended ultrasonic waves can be suppressed.

  In the above-described embodiment, an example is shown in which the pseudo engine sound is generated in front of the vehicle S when the vehicle S is traveling forward. However, the pseudo engine sound is generated behind and behind the vehicle S when the vehicle S is traveling backward. May be provided.

  The mounting position of the ultrasonic speaker 5 and the vehicular horn 4 that generates the pseudo engine sound is not limited to the front portion of the vehicle S. It may be provided so as to radiate a pseudo engine sound toward the rear periphery of the vehicle S when the vehicle is traveling backward (during back travel).

  The term “pedestrian” used in the above specification is a general term for a “person” to be protected when the vehicle is traveling, and is not necessarily limited to a “walking person” in a narrow sense. That is, it naturally includes a person who is running, a person who is stationary, a person who is sitting, a person who is in a wheelchair, etc. in the vicinity of the vehicle S or in the traveling direction of the vehicle S.

DESCRIPTION OF SYMBOLS 1 Parametric speaker 2 Movable iron core 3 Diaphragm 4 Vehicle horn 5 Ultrasonic speaker 6 Main body apparatus 14 Fixed contact 15 Movable contact 23 Pseudo engine sound preparation part 24 Ultrasonic amplitude modulation part 25 Ultrasonic speaker amplifier 26 Horn drive amplifier alpha Parametric speaker Range of simulated engine sound due to vehicle β Range of simulated engine sound due to vehicle horn γ Area where false recognition occurs due to reflection of ultrasonic waves S Vehicle

Claims (5)

In the vehicle presence notification device that notifies the presence of the vehicle (S) by generating a pseudo engine sound toward the outside of the vehicle,
This vehicle presence notification device
A parametric speaker (1) for emitting ultrasonic waves obtained by ultrasonically modulating the pseudo engine sound toward the outside of the vehicle;
When a self-excited voltage equal to or greater than a threshold value is applied with direct current, the magnetic force is interrupted to vibrate the movable iron core (2), and the diaphragm (3) coupled to the movable iron core (2) is moved to the movable iron core (2 ) And a vehicle horn (4) that generates an alarm sound by vibrating together,
A vehicle existence characterized in that an electric signal forming a pseudo engine sound by a separately excited voltage lower than the self-excited voltage is applied to the vehicle horn (4) to generate a pseudo engine sound from the vehicle horn (4). Notification device. The vehicle presence notification device according to claim 1,
The vehicle presence notification device, wherein the ultrasonic speaker (5) in the parametric speaker (1) and the vehicle horn (4) are disposed adjacent to each other. The vehicle presence notification device according to claim 2,
The vehicle presence notification device includes ultrasonic directivity expanding means for expanding the directivity of ultrasonic waves generated by the ultrasonic speaker (5) when the traveling speed of the vehicle (S) is equal to or lower than a predetermined speed. A vehicle presence notification device. In the vehicle presence notification device according to claim 3,
This vehicle presence notification device increases the sound pressure of the pseudo engine sound generated by the vehicle horn (4) when the ultrasonic directivity extending means widens the directivity of the ultrasonic speaker (5). A vehicle presence notification device. In the vehicle presence notification device according to any one of claims 1 to 4,
The vehicle horn (4) is a vehicle presence notification device that generates a warning sound by being supplied with the self-excited voltage when a horn switch operated by a vehicle occupant is turned on.

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