JPS5995796A - Digital speaker - Google Patents

Abstract

PURPOSE:To attain accurate D/A converting performance by grouping an electroacoustic transducer one electrode of which is made of plural unit electrodes so as to obtain an area proportional to each digit weight of a parallel PCM signal and driving the transducer. CONSTITUTION:One electrode 21 of a couple of flat electrodes made by inserting a piezoelectric element 23 is taken as a common electrode (diaphragm) and the other electrode 22 is divided into plural unit electrodes 22a having the same area. Each electrode 22a is grouped so as to obtain an area proportional to the weight of each bit digit of the parallel PCM signal and coupled in parallel and they are scattered radially almost uniformly. Since the grouped electrodes 22a in this way are driven independently in response to the state of each bit of the parallel PCM signal, the accurate D/A converting output.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to PCM (Pulse Code Mod
The present invention relates to a digital speaker that is applied to a reproduction device for audio signals converted into .

BACKGROUND TECHNOLOGY AND PROBLEMS In recent years, even in the field of audio equipment, by handling audio signals as PCM, it is possible to improve the S/N ratio, expand the dynamic range, and PCM conversion of audio signals is being actively adopted due to various advantages such as reduction in non-linear distortion.

By the way, in order to digitize an audio signal waveform, which is an analog signal, sampling is performed at a repetition frequency twice the highest frequency included in the audio signal according to the sampling theorem, and the sampled value is converted into a binary code. However, in order to recover the original audio signal from this binary code, it is necessary to provide a D/A conversion function in one of the paths of the reproduction system. Therefore, various digital speakers have been proposed that perform direct D/A conversion during the electro-acoustic conversion process.

In a conventional digital speaker, a parallel PCM digital signal as an audio signal is directly supplied to a drive unit, and a driving force corresponding to the weight of each bit digit of the parallel PCM digital signal is generated as shown in FIGS. 1 and 2, for example. As shown, the signals are generated in each driving section and combined on a common diaphragm (membrane) to perform D/A conversion and reproduce an acoustic signal (analog sound).

In the piezoelectric shop's digital conference speaker shown in Figure 1,
Of a pair of flat plate electrodes with a piezoelectric element interposed between them, one flat plate electrode (1) is used as a common electrode (diaphragm), and the other flat plate electrode (2) is used as a common electrode (diaphragm). Divide the electrodes into the electrodes to which the driving force is to be applied, and make each electrode into a < M S B bit (maximum M) electrode (2
a), (MSB-1) Hift 0)'FIL pole (2b)
, (MSB-2) bit electrode (2s, (NiSB-3
,) Hypantono electrode (2d), (λ+5B-4) bit electrical contact (26 inputs (MSB-5) bit (LSB bit)
electrode (2f).

A chair parallel P CM signal is supplied to each electrode, and when the bit digit coefficient is "1", a voltage is applied to the corresponding electrode,
A driving force corresponding to the weight of the bit digit is generated and synthesized on the diaphragm (flat plate electrode (1)).

In addition, in the electrodynamic digital speaker shown in Fig. 2, the voice coil (lυ is a coil (12a) with a different number of turns).
, (12b), (12C)...
..., and these coils (12a included (12b)
, (12G)・・・・・・・・・・・・ is parallel P
The number of turns is determined to provide a driving force proportional to (corresponds to) the weight of each bit digit of the CM signal. To provide this driving force, the current flowing through the coil may be made to correspond to the weight of each bit digit instead of the number of turns of the coil. The diaphragm θ3) is vibrated with a driving force proportional to the weight of each bit digit, and the vibrations are synthesized on the diaphragm (membrane).

However, in the conventional digital spill force shown in Figs. 1 and 2, the drive units in charge of each bit digit in order to generate the drive force representing the weight of each bit digit of the parallel PCM signal are generally identical. As a result, errors occur in the sound pressure frequency characteristics, phase characteristics, and propagation times between the respective driving forces, making it difficult to perform correct D/A conversion and, therefore, correct playback. For example, in the case of Fig. 2, since the number of turns is different, the inductance is different from the perspective of the drive system, and the distance from the drive part to the diaphragm is also different, so the difference in the propagation time of the drive energy to the diaphragm (13) is caused. Distortion occurred and therefore correct D/A conversion was not possible.

Furthermore, once the weights of the eaves moving parts were determined, it was impossible to reproduce PCM signals with different M depths using the cohed method.

In addition, since the driving force responsible for each bit of the PCM signal is concentrated in a part of the diaphragm (membrane), correct D/
A conversion was difficult. For example, in the case of Figure 1 above,
From the perspective of the drive system, the capacitance is different for each drive part, and the long drive part is unevenly distributed in a part of the diaphragm all year round.
Correct D/A conversion was difficult.

OBJECTS OF THE INVENTION The present invention solves these conventional problems and provides parallel PCM.
To prevent errors in characteristics (sound pressure frequency characteristics and phase characteristics) between the driving forces corresponding to the weights of each bit of the signal,
This allows correct D/A conversion by adding and combining forces on the same diaphragm, and any PCM signal with a different length code system (weight) can be converted into D/A by easily changing the weight according to the code system. It is an object of the present invention to provide a digital speaker which can be converted, thereby improving audio reproduction quality, and which has a simple structure and is easy to manufacture.

Summary of the Invention The present invention includes an electro-acoustic transducer that applies a voltage between a pair of flat electrodes to extract sound pressure, one of which is divided into a plurality of unit electrodes each having a uniform area. The unit electrodes are connected in parallel in parallel 1) in a group so that the area is proportional to the weight of each bit digit of the CM signal, and each bit digit can be driven, and the unit electrodes forming each group are approximately This invention relates to digital speakers characterized by being evenly distributed.

Example Embodiments of the present invention will be described below with reference to the drawings.

FIG. 3 is a plan view of a piezoelectric transducer showing an embodiment of the digital speaker according to the present invention. In the same figure, one of the piezoelectric elements (a pair of flat plate electrodes with fangs inserted therein (21) is used as a common electrode (diaphragm), and the other flat plate electrode (22) is used as a pair of flat plate electrodes (21) as shown in the figure. It is divided into unit electrodes (22a) with the same area.These unit electric charges (22a) are grouped and connected in parallel so that the area is proportional to the weight of each bit digit of the parallel PCM. A unit electrode (22a
, ) are approximately evenly distributed radially. For example, unit electrode <';'2a) MSB every 61st
Return to the client and then return the telephone number (22a) -
'k Every third unit electrode (22a) is set as a bit (84813-1), and every seven unit electrodes (22a) are set as a set of (848B-2) bits. Thereafter, unit electrodes (22a) are similarly selected so as not to overlap each other to form each hit digit.

Each unit electrode (22a) is independently driven and reset. However, for each bit digit, each electro-mechanical converter (24) having an area proportional to the weight of the bit digit can be driven by the same driving source as shown in FIG. That is, when a pulse input is applied to the input terminal (11), the electro-mechanical converters (2a) of that bit digit provided on the output side are driven in parallel. In FIG. 4, T1 and T2 are transistors, R11
is resistance, 10v. 0 is the power supply.

As described above, in response to a parallel PCM signal, the number of electromechanical converters proportional to the weight of each bit digit is equal to the sound pressure frequency characteristic, the phase characteristic, and the same driving force is generated. Since they are driven in parallel, there is no difference in characteristics between the respective driving forces. Therefore, by adding and synthesizing the forces on the same displacement plate (2t), correct D/A conversion can be performed, and it is possible to improve the audio reproduction quality. Furthermore, since each unit electrode is evenly distributed, the driving force is not unevenly distributed, and distortion is less likely to occur during addition and synthesis. Note that even if the PCM signal code system (weight) changes, the number of electro-mechanical converters to be driven, that is, the number of unit triggers, can be freely changed. can also be dealt with.

As described above, in this embodiment, pressure [
Although the case of Ru has been mentioned, the present invention is not limited thereto and can be similarly applied to the case of a reservoir type.

Effects of the Invention If the present invention is used, parallel PCM (parallel PCM), the number of which is proportional to the weight of each bit digit of the Since the components are driven simultaneously and independently, there is no difference in characteristics between the respective driving forces (the forces can be added and combined for PCM signals of any code type on the same diaphragm (membrane)). By doing so, it is possible to perform D/A conversion correctly and improve the audio playback quality.In addition, the driving force for each bit digit is generated with equal distribution to the common diaphragm, so it is possible to perform D/A conversion correctly and improve the audio playback quality. As such, the driving force is not unevenly distributed, and when it is added and combined on the diaphragm, there is less distortion, and therefore more accurate /A conversion is possible.Roughly speaking, according to the present invention, one of the pair of flat electrodes One of the electrodes is subdivided into a large number of units), a unit sounding body is constructed for each unit, and these units are also distributed approximately evenly in numbers corresponding to the weights of each bit digit. So,
By changing the grouping of units, it is possible to easily apply the PCM signal to a PCM signal of another code system in which each digit has a different weight. Furthermore, the present invention is easy to manufacture due to its simple packaging.

[Brief explanation of drawings]

FIG. 1 is a simplified plan view of a piezoelectric transducer portion of a conventional digital speaker, FIG. 2 is a simplified side view of an electrodynamic transducer portion of a conventional digital speaker, and FIG. 6 is a simplified side view of a piezoelectric transducer portion of a conventional digital speaker. FIG. 4 is a plan view of essential parts showing one embodiment, and is a circuit diagram showing an example of the drive circuit of the digital speaker shown in FIG. 6. In addition, in the symbols used in the drawings, (2J)...
・・・・・・・・・・・・・Common electrode (diaphragm) (2 electrodes (22a)...
・・・・・・Unit electrode (2 total・・・・・・・・・・
...It is a piezoelectric element. Agent Masaru Ueya, Yoshio Tsunekami, Toshiki Sugiura (voluntary) procedural amendment dated 1/8/1980, Commissioner of the Japan Patent Office1, Indication of the case, UJR Application No. 206498, filed 1980, 2, Title of the invention. Digital Speaker (,218) Sony Corporation 6. Number of Inventions Increased by Amendment (1), Insert the following sentence between the 5th and 6th lines of the specification letter, page 8. "The unit electrode (22a) of each electro-mechanical converter (24)
) Various methods can be considered for drawing out the lead wires from the terminal. For example, each lead wire (32) in a ring shape having each end (32a) of a conductor pattern formed on a flexible board (insulating board) GU shown in the lead terminal device of FIGS. 5 and 6. The portion (33a) and the disk-shaped portion (33b) are as shown in FIG. 7 (FIG. 7 shows the case where it is applied to FIG. 6, but the same applies to the case where it is applied to FIG. 5, so the explanation will be omitted. ) Flat electrode t2 in Fig. 3
21 on each end of each drawer lead wire country (32
A) may be connected to the corresponding unit electrode (22a) using solder or conductive paint (adhesive), and a lead wire may be drawn out from each unit electrode (22a). Also, as shown in Fig. 8, one flat plate electrode (diaphragm) C2
J
Connect the end of the electrode 2a) with conductive paint (glue) or the like, and attach the flexible substrate (31
1f Lead 1G33 consisting of a conductor pattern formed by K
Alternatively, lead wires may be drawn out from each unit electrode when connecting the flat cable. ”(
2), Opening: Page 10, line 15, “It is a circuit diagram.”
The circuit diagrams, FIGS. 5 and 6 are simplified perspective views showing each side of the lead wire draw-out terminal device applied to the digital speaker of FIG. 3, and FIG. 7 is the lead wire draw-out terminal device 7 of FIG. 6. An explanatory diagram showing an example of a lead wire drawing method when connecting the terminal device to the flat plate electrode I2 in FIG. 3 and drawing out the lead wire, FIGS. 8(a) and (b) are respectively FIG. 7 is a perspective view and a side view showing another example of a lead wire drawing method applied to a speaker. ” he corrected. (3), Figures 5, 6, 7, 8 (a), and 3) have been added as separate sheets.

Claims (1)

[Claims] Electricity that extracts sound pressure by applying voltage between a pair of flat electrodes
It is equipped with an acoustic transducer, one electrode of which is divided into a plurality of unit electrodes with approximately uniform area, and these unit electrodes are grouped so that they form a surface aG proportional to the weight of each bit digit of the parallel pcM code. What is claimed is: 1. A digital speaker characterized in that the unit electrodes forming each group are connected in parallel and driven for each bit digit, and the unit electrodes constituting each group are substantially evenly distributed.