JPS6048700A - Piezoelectric electroacoustic transducer - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electroacoustic transducer that converts encoded digital electrical signals directly into analog acoustic signals.

In recent telecommunications, 11! Even in the u-frequency region, P
The reason why CM signals are used is that they are less likely to be affected by noise compared to conventional amplitude modulation or analog signals, and therefore have a large noise level and can be transmitted with low distortion. J (In addition to the merits of fishing for fishing, it is immeasurable in terms of signal processing, such as recording in large-capacity memory, combining with video and other data, and combining the processor with 1 Σ for signal synthesis and analysis. This is because it has advantages.

Conventionally, in order to finally convert a coded digital electrical signal that has such characteristics into an acoustic signal, an electrical A converter is used to convert it into an analog electrical signal, which is then converted into an acoustic signal using a conventional electroacoustic converter 2. The most common method was to convert it into a signal. However, this method not only requires an expensive A converter, but also requires an output amplifier that can withstand the maximum value of the displaced analog electrical signal, making it uneconomical because the normal output is small compared to the capacity of the amplifier. However, there were drawbacks such as increased nonlinear distortion and limited precision, which diminished the essential benefits of digital signal processing. To eliminate these drawbacks, electroacoustic transducers exist that convert dental electrical signals directly into analog acoustic signals. For example, in Japanese Patent Publication No. 54-12049, one pressure 7I
The L element is provided with electrodes equal to the number of bits, and this piezoelectric element is
A transducer with an 11" diameter coupled to a diaphragm is disclosed. Although these work in principle, in practice it is difficult to reproduce accurate signals due to the split vibration of the piezoelectric element. It is.

Another example is the JJ6 speaker, which is an electrodynamic transducer and has a number of voice coils equal to the number of hits wound around a common winding frame, and this winding frame is connected to one diaphragm. In a speaker with this structure, the voice coil of the bit where there is no input signal pulse also moves, which reduces efficiency due to back electromotive force, and increases the number of corner stand coils and coil weight due to a large number of focus points, which causes the vibration system to deteriorate. This becomes too large and difficult to implement as a speaker.

The present invention relates to an electric sound converter that is capable of directly converting a dental electrical signal into an analog acoustic signal without sacrificing the advantages of digital signal processing (and eliminating all of the above-mentioned disadvantages). ), tb),
The operating principle and structure will be explained in detail with reference to (c), (d), and FIGS. 2, 3, and 4.

Figure 1 ta), tb), tc), Ice)
is an example showing the correspondence between signal encoding and waveform used in the electroacoustic transducer of the present application. Figure 1 (al indicates the correspondence between the analog number and the number of tesicles, N is the number of hints, and its most significant bit (MSf3) is the polarity determination "1" hit of the analog signal. The analog value is the remaining N-1 bits. Each hit, for example, N −1
The th bit is equal to 2N-2 in the original analog 1st shift.
'', but this corresponding analog value is called the weight of P1-. Also, (MSB) is l if the corresponding analog signal is positive.
If it is negative, it becomes O.

tb+ in FIG. 1 is a dental electrical signal that is the signal expressed in binary code in FIG. 1(a), where 1 in the code corresponds to one electrical pulse. In the figure, 1b, 11)'... are the electric pulses of the first bit 1.2b, 2b'...
・ is the second bit υB electric pulse, (N-1)b, (N
-1,) b'... is an N-1 bit electric pulse,
Mb, Ml)'... represent the (MSB) electrical pulses, respectively, and the dotted line A is an analog signal, ASb
, A, S l)' are the sampled analog signals. FIG. 1 (cl is the digital electric signal waveform applied to the electric sound H′B≦ converter using the drive method of the present invention. These signals are generated by constant amplitude pulses whose polarity is defined by the MSB signal. 1'r4 is the dental electrical signal generated. FIG. Since the applied signal pulse has a constant amplitude of 11'', the converter must have a structure such that the conversion g+MB connected to each bit is a displacement proportional to the weight of each bit. That is, ],
d, 1 d'· is the displacement of a part of the converter corresponding to the first focus, and if this displacement is taken as 1, then the displacement 2d, 2d' corresponding to the second bit has a magnitude of 2, and hereafter, the displacement corresponding to the N-1 bit is expressed as The displacements (N-1)d and (N-1)d'.- are required to be -2 magnitude 2.

The displacements from these transducers are summed up to become Ad and Ad', which correspond to the amplitude of the diaphragm.By averaging these, the diaphragm produces an acoustic signal ASd (dotted line) that is equivalent to the Mokichi analog waveform. radiate.

In Figures 2 and 3, 31 , 32 , , 3
(N-1) has (N-1) pressures m, each having the same width and a length proportional to the weight of the corresponding bit, each corresponding bit of the amplifier.

are electrically coupled to the output terminals of the output terminals such that the displacements are alternately of opposite polarity.

4.4' is a connecting rod that connects adjacent piezoelectric crystals at both ends in the longitudinal direction, and 5 is a connecting rod that connects the same <J: f-, type elements at one point in the center. . 2 is a diaphragm, 6
is the base of the piezoelectric type rhombus vessel.

(N-1) The piezoelectric element of the cylinder is the piezoelectric element of the 1st bit and the piezoelectric element of the 2nd bit.
The number one piezoelectric element is connected, and both ends are connected with rods 4 and 4'.
The piezoelectric element of the second bit and the piezoelectric element of the third bit are connected at the center by a coupling rod 5, and then sequentially by coupling rods 4 and 4'.
The piezoelectric element corresponding to the final bit is connected to the center part when (N-1) is an even number, and to both ends when (N-1) is an odd number. , are firmly supported by the base body 6.

A diaphragm 2 is connected to the center of the piezoelectric element corresponding to the first hit and the IS.

When a constant-voltage electric signal pulse shown in the first Z (C1) is applied to each element of the piezoelectric electroacoustic transducer having the configuration described in 1 above, so that the displacements of the valley elements alternately have opposite polarities, the fourth As shown in the figure, the amount of displacement of the piezoelectric element is proportional to its length, so
Each element produces a displacement corresponding to the weight of each person, and since each piezoelectric element is coupled mechanically and in a dependent manner, the diaphragm 2 is able to absorb the displacement of all piezoelectric elements. oscillates with the added inversion, reproducing the analog signal Ad shown by the dotted line in FIG. 1(d).

As mentioned above, the piezoelectric type '#d air tone barrel transducer of the present invention has the above-mentioned structure, and since each piezoelectric element is independent for each hit, there is no reaction to the bit to which the signal pulse is not applied. Since it has a small amount of noise and good linearity, it is possible to reproduce faithfully to the original signal, and as a piezoelectric electroacoustic transducer that converts an N-bit encoded tental electric signal into an analog acoustic signal, it is used as a piezoelectric electroacoustic converter. , speech synthesis equipment, or audio (3) devices in general.

[Brief explanation of drawings]

Figure 1 (Is al an analog value or N-bit binary?) Code system and
. The IJ tbl is a diagram showing the correspondence between the samplerized analog signal, the N-bit binary code value, and the decile.
' Correspondence diagram with electric signals, Figure (C) is a waveform diagram of the tental electric signal applied to the electric sound system 2 converter of the present invention, Figure +cl+ is the electric signal represented by tel in Figure 9. This is an explanatory diagram of the output sound pressure of the element corresponding to each bit of the electroacoustic transducer of the present invention when the electroacoustic transducer of the present invention is moved, and the spatially synthesized sound (No. 8). 2 is a diaphragm, 31, 32... 3(N-1) is a piezoelectric element, 4.4' is a bond between both ends of the piezoelectric element, 5 is a bond π at the center of the piezoelectric element, and 6 is a base.

Claims (1)

[Claims] ], polarity determination bin) A piezoelectric electroacoustic transducer oil for converting N-bit encoded digital electric signals including MSB into analog acoustic signals. (N-1) piezoelectric elements (3), (32) having a length corresponding to the weight of each bit of an electrical signal encoded by <(N-1) bits and having equal widths. ,
...(3(N-1)), and a coupling 1'T'(4) that couples the elements to each other at both ends in the longitudinal direction of the piezoelectric element,
(4'), a coupling rod (5) which connects the piezoelectric elements to each other at the center of the piezoelectric element, and a vibration plate (2').
) and the base body (6) of the converter 3, and the (N-1
) hydrogen atoms are connected sequentially in a ladder-like manner by connecting rods (
4) A vibration plate (2) is connected to the center of a piezoelectric element (31) corresponding to the first bit of the first class, which is connected using four or connecting rods (5) alternately. The piezoelectric element (3 (N-1)) in the lower stage (N-1) is a piezoelectric type ``cardiac acoustic transducer'' which is connected to the base (6) at both ends or at the center.