JPH06105389A - Expired air flow sensor - Google Patents

Abstract

PURPOSE:To form the expired air flow sensor with stable detection sensitivity by providing plural sensor units whose sensor elements are provided in face with a gas chamber having sound reception holes to the sound reception face of a case, summing outputs of the sensor elements with an adder and outputting the sum. CONSTITUTION:A sensor element 1 is fixed to a gas chamber 4 formed with a unit case 3 whose one end is open and has sound reception holes 2 so that a detection face is exposed to an inner side face to form a sensor unit 5. Then the electric circuit consists of a mixer 7 summing outputs of the sensor elements 1a, 1b,...,1d, an amplifier 8, a rectifier circuit 9 and a peak hold circuit 10. An expired air flow produced from a mouth reaches the sound reception face 6a of the case 6 and flows into the gas chamber 4 through the hole 2 to increase the pressure of the gas chamber 4. Then the pressure rise is detected by the sensor elements 1a-1d, the outputs are added by the mixer 7, the amplifier 8, the rectifier circuit 9 and the peak hold circuit 10 to allow the unit 5 to detect stably a changing expired air flow.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expiratory flow sensor used in a speech utterance training device.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for a call flow sensor used in a speech utterance training apparatus that has a high detection efficiency and a stable detection sensitivity for the call flow generated from the mouth.

A conventional exhalation airflow sensor will be described below with reference to FIG. As shown in the figure, the sound receiving surface 31a
An air chamber 32 is formed in a case 31 having
A pressure sensor 33 is provided so that the pressure detection surface is exposed, and a sound receiving hole 34 for introducing the exhaled airflow generated from the mouth into the air chamber 32 is provided on the sound receiving surface 31a. The operation of the exhalation airflow sensor having the above configuration will be described. The exhalation airflow generated from the mouth is guided into the air chamber 32 through the sound receiving hole 34 provided in the sound receiving surface 31a, and the pressure in the air chamber 32 rises. To be done.

Then, the pressure sensor 33 having a pressure detection surface exposed in the air chamber 32 detects the rise in pressure to detect the exhalation airflow.

As this type of exhalation airflow sensor, the one disclosed in Japanese Patent Laid-Open No. 1-255898 is known. That is, a front air chamber is provided at the front of the microphone, a plurality of sound holes for ventilating the front air chamber are arranged on a curved front plate, and a plurality of microphones are provided by one detection microphone. It tries to get the work done.

[0006]

In such a structure of the conventional exhalation airflow sensor, since the exhalation airflow generated from the mouth changes vertically, the exhalation airflow sensor is changed by the generated sound. The relative positional relationship between the mouth and the mouth has to be adjusted, and the adjustment is very cumbersome, and in the former case, the sound receiving hole 34 provided in the sound receiving surface 31a.
It is difficult to optimize the shape of the air chamber 32, and there is a problem that the detection sensitivity of the exhalation airflow sensor varies.

Also in the latter, similarly to the former, it was difficult to optimize the sound holes and the front air chambers provided in the front plate.

Further, as a latter conventional example, it is shown that a plurality of electret condenser microphones are used, but each microphone is not formed as a unit having an air chamber, and the output of the microphone is Since they are not output by adding, the productivity is poor, and it is difficult to detect the exhalation airflow in a stable state.

An object of the present invention is to solve the above problems, and an object thereof is to provide an expiratory airflow sensor having improved productivity, good detection efficiency, low cost, and stable quality.

[0010]

In order to achieve the above object, the first basic means of the expiratory flow sensor of the present invention is to detect on the inner surface of the air chamber having one end opened to form a sound receiving hole. A sensor unit provided with a sensor element having an electret condenser microphone engaged so that its surface is exposed; and a case having a sound receiving surface on which a plurality of the sensor units are arranged. In this configuration, an addition unit that adds the outputs of the sensor elements of the sensor unit is provided.

The second means in addition to the first means is configured to add the outputs of the sensor elements and then output the sum through a low-pass filter whose cutoff frequency is equal to or lower than the vocal cord vibration frequency.

The third means in addition to the first means has a structure in which the opening area of the sound receiving hole of the sensor unit is smaller than the projected area of the exhaled air flow.

[0013]

According to the present invention, the basic structure of the above-mentioned first means causes the expiratory airflow emitted from the mouth to reach the sound receiving surface and flow into the air chamber through the respective sound receiving holes to increase the pressure in the air chamber. To do.

Since the pressure increase in the air chamber is detected by the sensor elements and the outputs of the respective sensor elements are added by the adding means and output, the pressure change due to the expiratory flow can be detected stably.

Further, when the structure of the second means is added to the first means, the cutoff frequency of the low-pass filter for removing the voice component generated at the same time as the expiratory flow is set to be equal to or lower than the vocal cord vibration frequency, so that the voice component is efficient It can be removed well, and only the pressure rise due to the expiratory flow can be detected.

When the structure of the third means is added to the first means, the opening area of the sound receiving hole is made smaller than the projected area of the expiratory flow, so that the pressure rise due to all the expiratory flow can be efficiently performed. It will be possible to detect.

[0017]

EXAMPLE 1 Example 1 of the present invention will be described below with reference to FIGS. 1 to 4.

As shown in the drawing, a sensor element 1 consisting of an electret condenser microphone (ECM) is opened at one end and a sound-receiving hole 2 is formed in a unit case 3. The sensor unit 5 is configured so as to be exposed so as to be fixed.

Further, the sound receiving hole 2 is the sound receiving surface 6 of the case 6.
a plurality of sensor units 5 are provided so as to face a,
A plurality of sensor elements 1a, 1b, 1c, 1d are arranged.
Then, as shown in FIG. 3, the electric circuit includes a mixer 7, an amplifier 8, a rectifier circuit 9, and a peak hold circuit 10 which are addition means for adding the outputs of the plurality of sensor elements 1a, 1b, 1c, 1d. It consists of and.

The operation of the exhalation airflow sensor having the above structure will be described. The exhalation airflow emitted from the mouth reaches the sound receiving surface 6a of the case 6, flows into the air chamber 4 through each sound receiving hole 2, and then the air chamber 4 Increase the pressure of.

The pressure increase in the air chamber 4 is detected by the sensor elements 1a, 1b, 1c, 1d, and the mixer 7, the amplifier 8, the rectifier circuit 9 and the peak hold circuit 1 are detected.
It is added by 0 and output.

The direction of the exhalation air flow emitted from the mouth changed as shown in FIG. 4, and according to the experiment, the direction change angle was about 60 degrees.

Therefore, in the first embodiment, the case 6 is used.
By providing a plurality of sensor units 5 on the sound receiving surface 6a, the exhalation airflow whose direction changes can be detected in a stable state.

(Second Embodiment) A second embodiment of the present invention will be described below with reference to FIGS. 5 and 6. The first
The same parts as those in the embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the figure, the sensor elements 1a, 1b,
After passing through the mixer 7 and the amplifier 8 for adding the outputs of 1c and 1d, a low-pass filter 11 for removing the voice component emitted from the mouth at the same time as the exhalation airflow is provided. The configuration is provided.

As shown in FIG. 6, the voice component is distributed above the vocal cord vibration frequency, and the vocal cord vibration frequency is lowest in the adult male and is said to be around 150 Hz. Therefore, the cutoff frequency of the low-pass filter 11 is 70 Hz to 120 H, which is lower than the vocal cord vibration frequency.
By setting z, the voice component can be efficiently removed, and only the pressure increase due to the expiratory flow can be detected.

(Third Embodiment) A third embodiment of the present invention will be described below with reference to FIG. The same parts as those in the first embodiment are designated by the same reference numerals and detailed description thereof will be omitted.

As shown in the figure, the opening area a × b of the sound receiving hole 2 provided in the sensor unit 5 is made smaller than the projected area of the expiratory flow.

That is, in order to efficiently increase the pressure in the air chamber 4, it is necessary that the pressure applied to the sound receiving hole 2 is uniform, as is well known. Further, since the exhalation airflow is the most beam-shaped and the divergence angle is 15 degrees, in order to detect the pressure increase due to all the exhalation airflow, the opening area a × b of the sound receiving hole 2 is detected.
Must be smaller than the projected area of the expiratory flow.

The opening area a × b is 5 square mm.
It has been found that the range of 30 to 30 mm 2 is the most efficient in terms of performance and manufacturing.

[0031]

As is apparent from the above embodiments, according to the present invention, a plurality of sensor units each having a sensor element facing the air chamber having the sound receiving hole are provided on the sound receiving surface of the case. Since the output of each sensor element is added by the addition means and output, an inexpensive air flow sensor with stable detection sensitivity can be provided.

[Brief description of drawings]

FIG. 1 is a sectional view of an exhalation airflow sensor according to a first embodiment of the present invention.

FIG. 2 is a perspective view of the exhalation airflow sensor according to the first embodiment.

FIG. 3 is a block diagram showing a configuration of an electric circuit of the exhalation airflow sensor of the first embodiment.

FIG. 4 is a schematic view showing an example of a change in the direction of the exhalation airflow emitted from the mouth of the first embodiment.

FIG. 5 is a block diagram showing the configuration of an electric circuit of the exhalation airflow sensor of the second embodiment.

FIG. 6 is a graph of a frequency spectrum detected on the sound receiving surface of the exhalation airflow sensor of the second embodiment.

FIG. 7A is a perspective view of a sensor unit of the exhalation airflow sensor of the third embodiment. FIG. 7B is a perspective view of the exhalation airflow sensor of the third embodiment.

FIG. 8 is a cross-sectional view showing the configuration of a conventional exhalation airflow sensor.

[Explanation of symbols]

 1a to 1d Sensor element 2 Sound receiving hole 4 Air chamber 5 Sensor unit 6 Case 6a Sound receiving surface 7 Adding means 11 Low-pass filter

Claims (5)

[Claims] 1. A sensor unit provided with a sensor element having an electret condenser microphone engaged with an inner surface of an air chamber having one end opened to form a sound receiving hole so that a detection surface is exposed, and the sensor unit. And a case having a sound receiving surface, and an adding means for adding the outputs of the sensor elements of the plurality of sensor units. 2. The expiratory flow sensor according to claim 1, wherein the output of the sensor element is added and then output through a low-pass filter whose cutoff frequency is equal to or lower than the vocal cord vibration frequency. 3. The expiratory airflow sensor according to claim 1, wherein the opening area of the sound receiving hole of the sensor unit is smaller than the projected area of the expiratory airflow. 4. The cutoff frequency of the low-pass filter is set to 7
The exhalation airflow sensor according to claim 2, which has a frequency of 0 Hz to 120 Hz. 5. The exhalation airflow sensor according to claim 3, wherein the sound receiving hole of the sensor unit has an opening area of 5 mm 2 to 30 mm 2.