JPH0413920Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] This invention relates to a piezoelectric speaker device.

[Prior Art] A piezoelectric speaker will be explained with reference to FIG.
Reference numeral 1 denotes a piezoelectric element, which is composed of a piezoelectric element plate 1a and a metal plate 1b made of brass or the like that is connected to the voltage element plate 1a while maintaining electrical connection, each forming a pair of electrodes. There is also a bimorph type piezoelectric element in which a similar connection is made between the voltage element plates via a metal plate, but from the purpose of this invention, the same effect can be obtained, so the illustrated unimorph type piezoelectric element will be explained.)

A cone-shaped diaphragm 2 is provided at the center of the piezoelectric element 1.
The top of the diaphragm 2 is fixed, and the outer peripheral edge of the diaphragm 2 is fixed to the opening edge of the frame 3.

Thus, the piezoelectric element 1 is suspended and held by the diaphragm 2.

Further, 4 is an input terminal, and 5 is a lead wire that electrically connects the input terminal 4 and the electrode of the piezoelectric element 1.

[Problems to be solved by the invention] In such a piezoelectric speaker, in order to avoid disturbances in frequency characteristics due to increase in sound pressure due to the primary resonance of the piezoelectric element 1, the basic resonance frequency of the diaphragm 2 is lower than the primary resonance frequency. Designed to raise resonance frequency ₀ .

Therefore, the diaphragm 2 should not vibrate during the primary resonance of the piezoelectric element 1, but the diaphragm 2 vibrates due to harmonic components of ₀ or more included in the primary resonance, and this is heard as distorted sound. There was a problem that deteriorated the sound quality.

Therefore, conventionally, as shown in FIG. 1, a damping agent 6 such as chloroprene rubber was bonded to one surface of the piezoelectric element 1 to suppress the primary resonance, but this was not effective enough. was not yet reached.

[Means for solving the problem] This invention consists of at least a frame, a diaphragm whose outer periphery is coupled to the opening edge of the frame, and a piezoelectric device coupled to the diaphragm and composed of a piezoelectric element plate and a metal plate. This is a piezoelectric speaker device in which a piezoelectric speaker equipped with an element is attached to a baffle plate to which an electrodynamic speaker is attached, and the metal plate is placed in a leakage magnetic field of the electrodynamic speaker.

[Operation] A braking force is generated by the eddy current generated by vibrating a metal plate, which is a conductor, in a magnetic field, and the braking force suppresses primary resonance.

[Embodiment] Fig. 2 shows an embodiment of this invention, in which an electrodynamic speaker 32 for bass reproduction is attached to a bump-full plate 31 of a speaker box, and a frame 3 and a , a diaphragm 2 whose outer periphery is coupled to the opening edge of the frame 3; a piezoelectric element plate 1a and a metal plate 1b which are coupled to the diaphragm 2;
A piezoelectric type speaker 22 consisting of a piezoelectric element is attached to the buff-full plate 31.

That is, the piezoelectric speaker 22 is placed in a leakage magnetic field 33 extending from the magnetic circuit of the electrodynamic speaker 32 to the end surface of the frame.

According to this configuration, the metal plate 1 of the piezoelectric speaker
b is placed in a magnetic field, an eddy current is generated in the metal plate 1b due to the bending movement of the metal plate 1b when the piezoelectric speaker is driven, and this causes the metal plate 1b to
The bending movement of is damped.

This damping action is noticeable during the primary resonance, where the amplitude is the largest, and at higher-order resonances, the eddy current is divided into small loops, resulting in a small damping force, so it has little effect on the acoustic radiation efficiency.

[Effects of the invention] According to this invention, it is possible to effectively suppress the generation of distorted sound due to primary resonance, and it is possible to obtain good reproduced sound.

Furthermore, by using it in combination with a braking material, the braking action can be further improved.

[Brief explanation of drawings]

Figure 1 is a sectional view of a conventional piezoelectric speaker, Figure 2 is a cross-sectional view of a conventional piezoelectric speaker.
The figure is a sectional view of an embodiment of this invention. 3... Frame, 2... Vibration plate, 1a... Piezoelectric element plate, 1b... Metal plate, 1... Piezoelectric element, 22
...piezoelectric speaker, 32...electrodynamic speaker, 31...battery plate, 33...leakage magnetic field.

Claims (1)

[Scope of utility model registration request] A piezoelectric type comprising at least a frame 3, a diaphragm 2 whose outer periphery is coupled to the opening edge of the frame 3, and a piezoelectric element 1 coupled to the diaphragm 2 and composed of a piezoelectric element plate 1a and a metal plate 1b. speaker 2
A piezoelectric speaker device characterized in that 2 is attached to a baffle plate 31 to which an electrodynamic speaker 32 is attached, and the metal plate 1b is placed in a leakage magnetic field 33 of the electrodynamic speaker.