JPH0110059Y2 - - Google Patents

Description

[Detailed description of the invention] (Field of industrial application) This invention is a so-called ear microphone that extracts the vibrations of the skull caused by airway sounds when a human speaks using an element inserted into the ear canal and obtains an electrical signal. It is related to.

(Prior art) A microphone that receives sound and outputs it as an electrical signal vibrates a diaphragm with the sound and converts the vibration of the diaphragm into an electrical signal by using changes in the magnetic field. When a person inputting audio to a computer is in a noisy place, the surrounding noise will naturally be picked up, which may be extremely inconvenient depending on the application.

As a solution to this problem, a so-called ear microphone has been developed, which uses an element inserted into the ear canal to extract the vibrations of the skull caused by airway sounds when a person makes vocalizations, and obtain electrical signals from them. This ear microphone uses an acceleration type vibration detector that uses a bimorph ceramic element such as zirconate titanate (PZT) as a conversion element.

Since this vibration detector must be housed inside a case that is inserted into the external auditory canal as described above, it is necessary to make the conversion element itself as small as possible. However, ceramic elements are basically
Because it is brittle against mechanical stress, it is difficult to make it thin and thin, and there are certain limits to what can be manufactured. Furthermore, since the bimorph element has a directional vibration mode, there is also the problem that the sensitivity varies depending on the direction of insertion into the ear canal.

(Purpose of the invention) The object of the invention is to provide an ear microphone that solves the problems of the prior art.

(Structure of the invention) In order to achieve the above object, the present invention forms a microphone unit by pasting a polymer piezoelectric film on the inner wall of a cylindrical case of a size and shape that can be inserted into the external auditory canal. It is a film that converts the vibrations of the skull into electrical signals.

(Example) Next, an example of the present invention will be described with reference to FIG. Reference numeral 1 denotes a case, which has an opening 2 at its tip and a bottom 3 closed at its base. This case 1 is made of a flexible material such as resin, and the opening 2 is covered with a cap 4, and at least half of the overall size and shape are suitable for insertion into the external auditory canal. . And this case 1
1 forming a microphone unit on the inner wall of the
A sheet of polymeric piezoelectric film 5 is pasted against ribs 6 provided in the case 1 at opposite ends thereof (see FIG. 2).

This polymer piezoelectric film 5 is deformed when the vibration of the skull caused by the airway sound of the user is transmitted to the case 1 in its diameter direction (the direction is undefined depending on the state of insertion contact), and both ends are in contact with the ribs 6. Therefore,
It receives compressive force in the plane direction (circumferential direction) and generates a voltage between electrodes provided on both sides.
The electrodes are connected by lead wires 7 and 8 to a connecting cord 10 via an impedance converter 9. In the figure, reference numeral 11 denotes a cushion, which provides stability when inserted into the external auditory canal.

This ear microphone constructed in this manner is used by inserting the cap 4 side of the case 1 into the ear canal. This inserted portion is subjected to vibration or pressure in the diametrical direction due to the sound vibration of the skull, compressing the polymer piezoelectric film 5 in the planar direction and generating an electric current. This electromotive force is transferred to the impedance converter 9
Output via .

In the embodiment described above, the polymer piezoelectric film was used in such a way that both ends of the polymer piezoelectric film were in contact with the ribs 6 inside the case 1, but the polymer piezoelectric film 5 is limited to only one sheet in this way. Without a doubt,
Provide a plurality of sheets, for example, three sheets as shown in FIG.
The outputs of these polymer piezoelectric films 5, 5, 5 may be connected in series, and in this way, high sensitivity can be obtained. In addition, when using a material that is subjected to uniaxial stretching processing such as PVDF for the piezoelectric film, it goes without saying that the stretching axes should be made to coincide with each other in the circumferential direction.

(Effects of the Invention) Since the present invention is constructed as described above, it has the effect of providing better conversion efficiency and higher clarity than the conventional accelerometer type ear microphone using a ceramic bimorph. Furthermore, since a polymer piezoelectric film is used, there is no cause for failure such as damage to the element. Another advantage is that the structure is extremely simple. Since the power generation element is cylindrical, there is no change in sensitivity depending on the insertion direction.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of one embodiment of the present invention, Fig. 2 is a sectional view taken along the - line in Fig. 1, and Fig. 3 shows another embodiment of the present invention with the same parts as Fig. 2. FIG. 1...Case, 5...Polymer piezoelectric film.

Claims (1)

[Scope of utility model registration request] An ear microphone characterized in that a microphone unit is formed by pasting a polymeric piezoelectric film on the inner wall of a cylindrical case that is sized and shaped to be inserted into the ear canal.