JP5716651B2 - Vehicle approach notification device - Google Patents

Description

  The present invention relates to a vehicle approach notification device that notifies the surroundings that a vehicle is approaching by generating sound from the vehicle.

  In recent years, electric vehicles (EV cars), hybrid cars (HV cars), etc. have structurally low noise, and it is difficult for pedestrians to notice the approach of these vehicles. A vehicle approach notification device that generates an approach notification sound is being mounted to increase the degree of recognition of being near (see, for example, Patent Document 1). In this vehicle approach notification device, as a sound generation method, sound generation data such as PCM (pulse code modulation) stored in a memory of a microcomputer, that is, a sound code converted into a data code and encoded is recorded at each sampling period. A method of generating sound by setting in a D / A converter or PWM output device is used. The output of the oscillating running sound by such a vehicle approach notification device is performed during low speed running with low road noise.

  The phonetic data mainly represents simulated running sounds such as simulated engine sounds and simulated motor sounds, and is stored in the memory as a certain amount of data. In the vehicle approach notification device, the approach notification sound is generated by repeatedly outputting the data for a certain amount of time. This phonetic data is a chord that combines multiple frequency components, and is expressed as a curve that draws the peak of a voice or electrical waveform, that is, `` coordinate and inflection of the head '' that raises or lowers the volume over time. "Sound fluctuation (envelope)" is added to make it easier for pedestrians to notice the approach of the vehicle.

JP 2009-35195 A

  However, since the sounding data is expressed in a form with “fluctuation” added, the amount of time of sounding data that must be memorized, that is, the length of time of sounding data increases, and the memory capacity increases. End up. In addition, there is a problem that due to time restrictions due to the memory capacity of the microcomputer, it is not possible to add sufficient “fluctuation” of sound such as “emphasis emphasis and inflection” to be pronounced.

  Moreover, even if “fluctuation” is added to the pronunciation data, there is a problem that the way the pedestrian hears the approach notification sound changes depending on the mounting location of the vehicle approach notification device in the vehicle and the sound insulation characteristics.

  In view of the above, the present invention provides a vehicle approach notification sound device capable of controlling the “fluctuation” of the approach notification sound to be optimal for the vehicle according to various situations, based on a small volume of pronunciation data. For the purpose.

  In order to achieve the above object, according to the first aspect of the present invention, the sounding data is read at a pitch corresponding to the carrier frequency from the memory means storing the sounding data of the vehicle approaching sound, and the approaching notification corresponding to the sounding data is obtained. The volume is adjusted by controlling the voltage level of the first sound output generator (27a) that generates the sound voltage waveform signal and the approach notification sound voltage waveform signal generated from the first sound output generator (27a). A first sounding voltage waveform signal generation unit having a first sound volume variable unit (26a), and reading sounding data from the memory means at a pitch corresponding to the carrier frequency, and an approach notification sound voltage waveform signal corresponding to the sounding data The second sound output output generator (27b) to be generated and the voltage level of the approach notification sound voltage waveform signal generated from the second sound output generator (27b) A second sound volume voltage generator (26b) having a second sound volume variable unit (26b) for adjusting the sound volume by controlling the voltage level by the first and second sound volume variable devices (26a, 26b). A mixer circuit (24) for mixing approach notification sound voltage waveform signals output from the first sounding voltage waveform signal generation unit and the second sounding voltage waveform signal generation unit, and an approach notification sound voltage after mixing by the mixer circuit (24) An amplifier (25) that causes the sounding body (3) to generate a sound of the vehicle approach notification sound by causing a current corresponding to the voltage of the waveform signal to flow through the sounding body (3) mounted on the vehicle. It is characterized by.

  As described above, the first and second sound output voltage generators (27a and 27b) and the first and second sound output voltage waveform signal generators including the first and second sound volume changers (26a and 26b) are simply configured. Accordingly, various “fluctuations” can be added to the approach notification sound by controlling the near notification sound voltage waveform signal. For this reason, it is possible to sufficiently add “fluctuation” only by storing in the memory means a small amount of sounding data that does not add “fluctuation (= envelope)” to the sounding data itself. Therefore, it is possible to provide a vehicle approach notification sound device that can control the “fluctuation” of the approach notification sound to be optimal for the vehicle in accordance with various situations based on the small volume of pronunciation data.

The invention as claimed in claim 1, from the sensor (1) for generating a sensor signal corresponding to the running state of the vehicle, having a sensor signal input circuit for inputting sensor signals (20), first sound voltage waveform The signal generator calculates the envelope frequency of the approach notification sound based on the sensor signal input to the sensor signal input circuit (20), and sets the volume setting value by the first volume variable device (26a) based on the envelope frequency. By setting and controlling the voltage level of the approach report sound voltage waveform signal, the volume of the approach report sound is raised and lowered along the envelope frequency, and the fluctuation due to the volume change is added to the approach report sound.

In this way, “fluctuation due to volume change (tremolo effect)” is added by raising and lowering the voltage level of the approach notification sound voltage waveform signal output from the first sound signal generator (27a) along the envelope frequency. It can be in the state. In this way, it is possible to realize a “fluctuation” effect by varying the volume.
According to the first aspect of the present invention, in the second sounding voltage waveform signal generation unit, the sounding data read start data by the first sounding output generation unit (27a) in the first sounding voltage waveform signal generation unit is predetermined. This is characterized in that the sounding data is read out from the memory means by providing the delay time.
As described above, by providing a predetermined delay time for reading the sounding data in the second sounding voltage waveform signal generation unit, it is possible to add “fluctuation” to the approach notification sound.
Further, in the first aspect of the present invention, the second sounding voltage waveform signal generation unit calculates an envelope frequency of the approach notification sound based on the sensor signal input to the sensor signal input circuit (20), and the envelope frequency The delay time is set based on the above.
As a result, “fluctuation (jet effect)” by setting the delay time according to the carrier frequency is added. In this way, it is possible to obtain a “fluctuation” effect by setting a delay time according to the carrier frequency.

The invention according to claim 2 has a sensor signal input circuit (20) for inputting a sensor signal from a sensor (1) for generating a sensor signal corresponding to the running state of the vehicle, and generates a first sounding voltage waveform signal. The unit calculates the envelope frequency of the approach notification sound based on the sensor signal input to the sensor signal input circuit (20), sets the carrier frequency based on the envelope frequency, and corresponds to the set carrier frequency The sound generation data is read by the first sound output generation unit (27a) at a pitch, thereby adding a fluctuation due to a variable carrier frequency to the approach notification sound.

  In this way, by controlling the frequency of the approach notification sound voltage waveform signal output from the first sound signal generator (27a), a state in which “fluctuation due to frequency change” is added can be achieved. In this way, it is possible to realize a “fluctuation” effect by changing the frequency.

For example, as described in claim 3 , the approach notification sound voltage output from the first sounding voltage waveform signal generation unit and the second sounding voltage waveform signal generation unit by the mixer circuit (24) with a delay time of 20 ms to 300 ms. By mixing the waveform signal, fluctuation due to long delay can be added to the approach notification sound. In this way, the “fluctuation” effect due to the long delay, for example, an echo corresponding to the long delay is applied, and the time for which the echo is applied varies depending on the delay time. It is possible to achieve the “fluctuation” effect that has been applied.

Further, as described in claim 4 , the delay time is set to 0.5 ms to 20 ms, and the approach notification output from the first sounding voltage waveform signal generation unit and the second sounding voltage waveform signal generation unit by the mixer circuit (24). By mixing the sound voltage waveform signal, fluctuation due to a short delay can be added to the approach notification sound. In this way, it is possible to realize a “fluctuation” effect due to a short delay, for example, a “fluctuation” effect to the extent that a human ear is identified as a synthesized sound or an echo.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows an example of a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is a circuit block diagram of a vehicle approach notification system including a vehicle approach notification device according to a first embodiment of the present invention. It is the functional block diagram which showed the vehicle approach notification system shown in FIG. 1 functionally.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
FIG. 1 is a circuit block diagram of a vehicle approach notification system including a vehicle approach notification device according to the present embodiment. FIG. 2 is a functional block diagram functionally showing the vehicle approach notification system shown in FIG. With reference to these drawings, a vehicle approach notification system including the vehicle approach notification device according to the present embodiment will be described.

  As shown in FIG. 1, the vehicle approach notification system includes a vehicle speed sensor 1, a vehicle approach notification device 2, and a speaker 3. In the vehicle approach notification system, based on the vehicle speed sensor signal transmitted from the vehicle speed sensor 1 by the vehicle approach notification device 2, the pseudo engine sound is output from the speaker 3 that is a sounding body during low speed traveling with a low road noise (for example, 20 km / h or less). Alternatively, an approach notification sound such as a pseudo motor sound is generated to notify a nearby pedestrian or the like of the approach of the vehicle. Here, the vehicle approach notification device 2 is separated from the speaker 3, but the speaker 3 may be integrated with the vehicle approach notification device 2.

  The vehicle speed sensor 1 outputs a vehicle speed sensor signal as a vehicle running state detection signal. For this reason, the vehicle approach notification device 2 inputs a vehicle speed sensor signal from the vehicle speed sensor 1 to acquire the vehicle speed and controls sound generation according to the vehicle speed while the vehicle is traveling at a low speed. Here, the sound is generated according to the vehicle speed, but the sensor that generates a sensor signal according to the traveling state of another vehicle, for example, the accelerator opening indicated by the sensor signal of the accelerator opening sensor that indicates the accelerator opening is indicated. The sound generation can be controlled according to the degree. Furthermore, it is possible to detect the ambient noise level indicating the ambient noise level using a microphone or the like and perform sound generation control according to the noise level.

  The vehicle approach notification device 2 includes a vehicle speed sensor signal input circuit 20, a microcomputer 21, a voltage control unit 22, a low-pass filter (hereinafter referred to as LPF) 23, a mixer circuit 24, and a power amplifier (hereinafter referred to as AMP) 25. .

  The vehicle speed sensor signal input circuit 20 is a part for inputting the vehicle speed sensor signal output from the vehicle speed sensor 1 described above, and transmits it to the microcomputer 21.

  The microcomputer 21 has a memory and an arithmetic unit corresponding to memory means (not shown), and has two DACs 21a and two PWM output devices 21b. The microcomputer 21 outputs two approach notification sound voltage waveform signals as sound output by the outputs from the two sets of DAC 21a and the PWM output device 21b and the voltage control unit 22 provided in each of the two sets as will be described later. Is generated. Among these, the DAC 21a and the voltage control unit 22 correspond to the volume variable device 26 (26a, 26b), and the PWM output device 21b corresponds to the sound generation signal generator 27 (27a, 27b). The two sets of DAC 21a, PWM output unit 21b, and voltage control unit 22 respectively generate first and second sounding voltage waveform signal generation units that generate approach notification sound voltage waveform signals that are sounding outputs of the respective groups. It is composed.

  The memory of the microcomputer 21 stores sound generation data such as PCM data representing a sound control program, simulated engine sound, simulated motor sound, and the like, as well as envelope frequency, carrier frequency, and volume (sound pressure). Data for setting level) are stored. For example, the microcomputer 21 stores an envelope frequency table associated with the vehicle running state such as the vehicle speed and the accelerator opening degree, a carrier frequency and delay time table associated with the envelope frequency, and the like in the memory. Using the tables stored in these memories, the microcomputer 21 uses an arithmetic device to calculate an envelope frequency corresponding to a traveling state such as a vehicle speed or an accelerator opening degree while driving at a low speed, or to respond to the envelope frequency. Calculate the volume, carrier frequency or delay time.

  Then, the microcomputer 21 reads out sound generation data for each sampling period corresponding to a predetermined carrier frequency, taking the delay time into consideration, for each of the first and second sound generation voltage waveform signal generation units, and outputs it to each PWM output device 21b. By setting, an approach notification sound voltage waveform signal corresponding to sounding data to be sounded is output from the PWM output device 21b. The approach notification sound voltage waveform signal at this time is still a signal before the volume is varied. Independent of the approach notification sound voltage waveform signal from the PWM output device 21b, the DAC 21a generates a control signal for varying the sound volume to be generated according to the envelope frequency.

  The voltage control unit 22 is provided corresponding to each set of the DAC 21a and the PWM output unit 21b, and changes the voltage level of the approach notification sound voltage waveform signal of the PWM output unit 21b based on a control signal transmitted from the DAC 21a. The voltage level of the approach notification sound voltage waveform signal of the PWM output device 21b is changed to the voltage level indicated by the control signal. Therefore, for example, the voltage level of the approach notification sound voltage waveform signal is decreased as the sound pressure level to be generated is decreased, and is output from the voltage control unit 22.

  The DAC 21a, the PWM output device 21b, and the voltage control unit 22 are shown as functional blocks, for example, as shown in FIG. That is, the PWM output device 21b serves as sound signal generators 27a and 27b that read sound data at a predetermined pitch using an oscillation signal generated by the low frequency oscillator 21c provided in the microcomputer 21 as a clock. One first sound signal generator 27a reads sound data at a predetermined pitch without a delay time, and the other second sound signal generator 27b starts reading sound data by the first sound signal generator 27a. The sound generation data is read out at a predetermined pitch by providing a delay time for the data. Further, the DAC 21a and the voltage control unit 22 adjust the sound output volume (VOL) by changing the voltage level of the approach notification sound voltage waveform signal generated from each of the first and second sound output generators 27a and 27b. It functions as the first and second volume variable devices 26a and 26b.

  The LPF 23 corresponds to a filter means, and is provided corresponding to each voltage control unit 22, and outputs corresponding to the output of the PWM output device 21 b transmitted through the voltage control unit 22 by removing high-frequency noise components. Is generated. For example, the LPF 23 stores a voltage corresponding to the output of the voltage control unit 22 in a built-in capacitor, and outputs it to the AMP 25 via the mixer circuit 24.

  The mixer circuit 24 mixes the output of each LPF 23. That is, the mixer circuit 24 generates an output of a voltage waveform obtained by synthesizing two approach notification sound voltage waveform signals from which noise components have been removed, and applies the voltage waveform output to the AMP 25.

  The AMP 25 causes a current corresponding to the output of the LPF 23 to flow through the speaker 3 based on voltage application from a constant voltage source (not shown). The sound pressure generated by the speaker 3 is determined according to the magnitude (amplitude) of the current supplied from the AMP 25, and the magnitude of the current supplied from the AMP 25 is determined by the output waveform of the LPF 23 corresponding to the PWM output. For this reason, the electric current which AMP25 flows based on adjustment of the voltage level in the voltage control part 22 can be changed.

  With the configuration as described above, a vehicle approach notification system including the vehicle approach notification device according to the present embodiment is configured.

  Next, a method of realizing “fluctuation” in pronunciation by the vehicle approach notification system configured as described above will be described. Here, an example of a technique for realizing “fluctuation” in sound generation by the vehicle approach notification system will be described. However, only one example is described here, and the first and second sound generation voltage waveform signal generation units generate By using the generated sound voltage waveform signal alone or mixing each signal, “fluctuation” can be realized by various methods other than the example shown here. Here, a method of realizing “fluctuation” in pronunciation will be described using the functional blocks shown in FIG.

  According to the vehicle approach notification system of the present embodiment, the voltage level of the approach notification sound voltage waveform signal output from the first and second sound signal generators 27a and 27b, that is, the volume setting value can be varied. By setting with the devices 26a and 26b, the volume of the pronunciation can be adjusted. Further, in the second sound generation signal generator 27b, by adjusting the delay time of the approach notification sound voltage waveform signal generated by the second sound generation voltage waveform signal generation unit, each of the first and second sound generation voltage waveform signal generation units. The phase of the approach notification sound voltage waveform signal that is output can be changed. Furthermore, the first and second sound signal generators 27a and 27b are adjusted by adjusting the pitch at which sound data is read by the first and second sound signal generators 27a and 27b so that the first and second sound signal generators 27a and 27b have the same pitch or different pitches. The frequency of each approach notification sound voltage waveform signal to be output can also be changed. Based on these operations, “fluctuation” in pronunciation can be realized by each of the following realizing methods, for example.

(1) Fluctuation realization method by changing the volume By changing the volume, "fluctuation" can be added to the approaching notification sound that is pronounced. For example, for the approach notification sound voltage waveform signal output from the first sound signal generator 27a, the volume setting value (voltage level) is adjusted by the first volume variable device 26a according to the envelope frequency calculated from the vehicle speed sensor signal. To do. That is, as the vehicle speed increases, the envelope frequency is increased, and the volume is increased or decreased in accordance with the envelope frequency, thereby adding “fluctuation (envelope)” by varying the volume to the approaching notification sound to be pronounced. In this case, the approach sound voltage waveform signal is not output from the second sound signal generator 27b.

  As a result, a voltage based only on the approach notification sound voltage waveform signal output from the first sound signal generator 27 a via the mixer circuit 24 is applied to the AMP 25. Since the voltage level of the approach notification sound voltage waveform signal output from the first sound signal generator 27a is raised and lowered along the envelope frequency, “fluctuation due to volume change (tremolo effect)” Can be added. In this way, it is possible to realize a “fluctuation” effect by varying the volume.

  Here, the envelope frequency is calculated in accordance with the vehicle speed, and the volume setting value is adjusted in accordance with the envelope frequency, but based on the driving state other than the vehicle speed, for example, the accelerator opening, the larger the accelerator opening, The envelope frequency may be calculated as a value that increases the envelope frequency. In addition to the driving condition, the envelope frequency can be calculated based on the ambient noise level indicating the ambient noise level, so that the envelope frequency increases as the ambient noise level increases. The envelope frequency may be calculated based on any one or more of the opening degree and the ambient noise level.

(2) Fluctuation realization method by changing carrier frequency (pitch) By changing the carrier frequency, that is, the frequency (pitch) of reading sound data, it is possible to add "fluctuation" to the sounding approach notification sound. For example, for the approach notification sound voltage waveform signal output from the first sound signal generator 27a, the carrier frequency (pitch) for reading the sound data in the first sound signal generator 27a is set to the envelope frequency calculated from the vehicle speed sensor signal. Adjust accordingly. In other words, the envelope frequency increases as the vehicle speed increases, the carrier frequency corresponding to it increases, and the pitch (that is, the sampling period) is shortened. "Fluctuation" due to variable frequency is added to the approach notification sound. In this case, the approach sound voltage waveform signal is not output from the second sound signal generator 27b.

  As a result, a voltage based only on the approach notification sound voltage waveform signal output from the first sound signal generator 27 a via the mixer circuit 24 is applied to the AMP 25. Then, since the frequency of the approach notification sound voltage waveform signal output from the first sound signal generator 27a is controlled, a state in which “fluctuation due to frequency change” is added can be achieved. In this way, it is possible to realize a “fluctuation” effect by changing the frequency.

  Here, the envelope frequency is calculated in accordance with the vehicle speed, and the carrier frequency (pitch) for reading the sounding data is adjusted in accordance with the envelope frequency. However, based on the driving state other than the vehicle speed, for example, the accelerator opening degree, etc. The envelope frequency may be calculated as a value such that the envelope frequency increases as the accelerator opening increases, and the corresponding carrier frequency (pitch) may be calculated. In addition to driving conditions, the envelope frequency can be calculated based on the ambient noise level indicating the ambient noise level so that the envelope frequency increases as the ambient noise level increases. The envelope frequency may be calculated based on any one or more of the opening degree and the ambient noise level.

(3) Fluctuation realization method by long delay The first sound signal generator 27a generates an approach notification sound voltage waveform signal by sequentially reading and outputting sound data at a pitch corresponding to the carrier frequency. On the other hand, the second sound generation signal generator 27b generates the approach notification sound voltage waveform signal by reading out and outputting sound generation data with a pitch corresponding to the carrier frequency and delayed by a predetermined delay time to be set. For example, an approach notification sound voltage waveform signal is generated by reading out and outputting sound generation data at an address to which an address counter value corresponding to a delay time is added. The delay time can be set according to the “fluctuation” to be generated, but can be set to about 20 ms (50 Hz) to 300 ms (3.3 Hz), for example.

  Each of the approach notification sound voltage waveform signals output from the first and second sound signal generators 27a and 27b is mixed by the mixer circuit 24 and then output. As a result, “fluctuation due to long delay” is added. In this way, the “fluctuation” effect due to the long delay, for example, an echo corresponding to the long delay is applied, and the time for which the echo is applied varies depending on the delay time. It is possible to achieve the “fluctuation” effect that has been applied.

  Note that the volume and frequency variable are not described here, but these have been described by the method shown in (1) the fluctuation realizing method by changing the volume and the method shown in (2) the fluctuation realizing method by changing the frequency. It can be made variable by such usage.

(4) Fluctuation realization method by short delay As in the case of the long delay, the first sound generation signal generator 27a reads out sound output data in order at a pitch corresponding to the carrier frequency and outputs it, thereby generating an approach notification sound voltage waveform. Generate a signal. The second sound generation signal generator 27b also generates an approach notification sound voltage waveform signal by reading out and outputting sound generation data with a pitch corresponding to the carrier frequency and delayed by a predetermined delay time to be set. For example, an approach notification sound voltage waveform signal is generated by reading out and outputting sound generation data at an address to which an address counter value corresponding to a delay time is added. The delay time can be set according to the “fluctuation” to be generated, but can be set to about 0.5 ms (2 kHz) to 20 ms (50 Hz), for example.

  Each of the approach notification sound voltage waveform signals output from the first and second sound signal generators 27a and 27b is mixed by the mixer circuit 24 and then output. As a result, “fluctuation due to a short delay (flanger effect)” is added. In this way, it is possible to realize a “fluctuation” effect due to a short delay, for example, a “fluctuation” effect to the extent that a human ear is identified as a synthesized sound or an echo.

  Here, the volume and frequency variable are not described here, but these are explained by the method shown in (1) the fluctuation realizing method by changing the volume and (2) the fluctuation realizing method by changing the frequency. It can be made variable by such usage.

(5) Fluctuation realization method by combination of delay and frequency (pitch) variable Fluctuation realization method by long delay or short delay in the above (3) and (4), and fluctuation realization method by frequency variable shown in (2) Depending on the combination, a “fluctuation” effect can be obtained. For example, the delay time is changed according to the envelope frequency calculated from the vehicle speed sensor signal and the corresponding carrier frequency. It is also possible to adjust the variable width of the delay time and the variable speed according to the carrier frequency.

  Thus, the delay time may be changed according to the carrier frequency. Also in this case, each approach notification sound voltage waveform signal output from the first and second sound signal generators 27a and 27b is mixed by the mixer circuit 24 and then output. As a result, “fluctuation (jet effect)” by setting the delay time according to the carrier frequency is added. In this way, it is possible to obtain a “fluctuation” effect by setting a delay time according to the carrier frequency.

  As described above, the first and second sound output voltage waveform signal generators including the first and second sound output generators 27a and 27b and the first and second sound volume changers 26a and 26b, that is, a simple configuration, With a simple circuit configuration using the microcomputer 21, the approach notification sound voltage waveform signal output from the microcomputer 21 is controlled to vary the volume, carrier frequency (pitch) variable, long delay, short delay or delay and carrier frequency (pitch). Various “fluctuations” in combination with variable can be added to the approach notification sound. For this reason, only by storing a small amount of sound generation data that does not add “fluctuation (= envelope)” to the sound generation data itself, it is possible to sufficiently add “head emphasis and inflection”, that is, “fluctuation”. It becomes possible.

  Therefore, it is possible to make a sound that allows a pedestrian to easily notice the approach of the vehicle. In addition, even when the pedestrian hears the approach notification sound depending on the mounting location of the vehicle approach notification device and the sound insulation characteristics, the program of the microcomputer 21 can control the “fluctuation” of the approach notification sound. It can be adjusted to the optimum “fluctuation”. Therefore, it is possible to provide a vehicle approach notification sound device that can control the “fluctuation” of the approach notification sound to be optimal for the vehicle in accordance with various situations based on the small volume of pronunciation data.

(Other embodiments)
In the above embodiment, the microcomputer 21 uses the DAC 21a to output a control signal, and generates a control signal for changing the sound pressure from the DAC 21a, thereby performing voltage control of the voltage control unit 22. However, the voltage control of the voltage control unit 22 may be performed using a PWM controller. When using the PWM controller, when changing the voltage level of the output waveform of the sound output in accordance with the temporal change amount of the value representing the running state such as the vehicle speed or the accelerator opening, for example, the vehicle speed or the accelerator opening Accordingly, the duty ratio for turning on / off the PWM output may be changed and the sampling period of the PWM output may be changed.

DESCRIPTION OF SYMBOLS 1 Vehicle speed sensor 2 Vehicle approach notification apparatus 3 Speaker 20 Vehicle speed sensor signal input circuit 21 Microcomputer 21a DAC
21b PWM output device 22 Voltage control unit 23 LPF
24 Mixer circuit 25 AMP
26 Volume controller 27 Sound signal generator

Claims (4)

A first sounding output generator for reading out the sounding data at a pitch corresponding to a carrier frequency from a memory means storing sounding data of a vehicle approaching sound and generating an approaching sound voltage waveform signal corresponding to the sounding data ( 27a) and a first volume variable unit (26a) that adjusts the volume by controlling the voltage level of the approach notification sound voltage waveform signal generated from the first sound output generator (27a). A first sounding voltage waveform signal generation unit;
A second sound output generator (27b) that reads out the sound generation data from the memory means at a pitch corresponding to a carrier frequency and generates an approach notification sound voltage waveform signal corresponding to the sound generation data, and the second sound output generation A second sounding voltage waveform signal generation unit having a second volume variable unit (26b) that adjusts the volume by controlling the voltage level of the approach notification sound voltage waveform signal generated from the unit (27b);
The approach notification sound voltage waveform output from the first sound voltage waveform signal generator and the second sound voltage waveform signal generator after the voltage level is controlled by the first and second sound volume adjusters (26a, 26b). A mixer circuit (24) for mixing the signals;
By passing a current corresponding to the voltage of the approach notification sound voltage waveform signal after mixing by the mixer circuit (24) to the sounding body (3) mounted on the vehicle, the sounding body (3) approaches the vehicle. An amplifier (25) for generating a notification sound ;
A sensor signal input circuit (20) for inputting the sensor signal from a sensor (1) that generates a sensor signal according to a running state of the vehicle;
The first sounding voltage waveform signal generation unit calculates an envelope frequency of the approach notification sound based on the sensor signal input to the sensor signal input circuit (20), and the first sound volume based on the envelope frequency. By setting the volume setting value by the variable device (26a) and controlling the voltage level of the approach notification sound voltage waveform signal, the volume of the approach notification sound is increased or decreased along the envelope frequency, and the approach notification sound is increased. Adds fluctuation due to variable volume to
In the second sounding voltage waveform signal generation unit, a predetermined delay time is provided for the reading start data of the sounding data by the first sounding output generation unit (27a) in the first sounding voltage waveform signal generation unit, The sound generation data is read from the memory means, and the envelope frequency of the approach notification sound is calculated based on the sensor signal input to the sensor signal input circuit (20), and based on the envelope frequency The delay time is set . A sensor signal input circuit (20) for inputting the sensor signal from a sensor (1) that generates a sensor signal according to a running state of the vehicle;
The first sounding voltage waveform signal generation unit calculates an envelope frequency of the approach notification sound based on the sensor signal input to the sensor signal input circuit (20), and calculates the carrier frequency based on the envelope frequency. Setting, and reading out the sounding data by the first sounding output generation unit (27a) at a pitch corresponding to the set carrier frequency, thereby adding fluctuation due to variable carrier frequency to the approach notification sound. The vehicle approach notification device according to claim 1, wherein The delay time is set to 20 ms to 300 ms, and mixing of the approach notification sound voltage waveform signal output from the first sounding voltage waveform signal generation unit and the second sounding voltage waveform signal generation unit by the mixer circuit (24) is performed. vehicle approach warning apparatus according to claim 1 or 2, characterized in that the addition of fluctuation due to the long delay in the approach warning sound. The delay time is set to 0.5 ms to 20 ms, and the approach notification sound voltage waveform signal output from the first sounding voltage waveform signal generation unit and the second sounding voltage waveform signal generation unit by the mixer circuit (24) is mixed. Accordingly, the vehicle approach warning system according to claim 1 or 2, characterized in that the addition of fluctuation due to a short delay in the approach warning sound.

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