JPH01208100A - System for driving electrodynamic plane driving speaker - Google Patents

Abstract

PURPOSE:To directly convert a PCM signal to an acoustic signal by burdening the weight even at an electric power supplying side in accordance with a bit signal supplied to a linear conductor when plural magnetic poles are provided through a little clearance at a diaphragm composed of an insulation material having a linear conductor and a speaker is obtained. CONSTITUTION:A linear conductor 2, which becomes a signal line, is provided on a flexible film and made into a diaphragm 1, a yoke 5 having plural permanent magnets 3 is provided on the lower surface at a little clearance on the front and rear, and a yoke 6 having plural permanent magnets 4 is provided on the upper surface, an acoustic hole 7 is made between respective magnetic poles and an electrodynamic type plane driving speaker is obtained. By such a constitution, a pulse code modulating signal is given to a linear conductor, a speaker is operated, at this time, the length and width of the linear conductor are changed in accordance with the bit signal equivalent to the number of the beats of the modulating signal, the weight is given and a part of the weight is burdened even to the electric power supplying side. Thus, the number of the linear conductors can be decreased and it is not necessary to D/A-convert a PCM signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a drive method for an electrodynamic planar drive speaker,
More specifically, the present invention relates to a drive method for an electrodynamic planar drive speaker that directly reproduces a pulse code modulated signal as an acoustic signal.

(Prior Art and Problems to be Solved by the Invention) Conventionally, in this type of electrodynamic planar drive speaker, the so-called pulse code modulation (hereinafter referred to as PCM) method, in which an acoustic signal is pulse encoded and transmitted or recorded and reproduced, has been used. It has the advantages of being resistant to distortion and recording, having a large dynamic ledge, and being able to be transmitted or multiplexed. This PC
To reproduce the M signal as an acoustic signal, after performing digital/analog conversion, the analog signal is supplied to the speaker and the acoustic signal is reproduced. Therefore, the signal generated by the digital/analog converter at the end of the system It has the disadvantage that it is greatly affected by noise.

In addition, with this PCM method, it is necessary to prepare the area ratio of the diaphragm corresponding to the bit signal, or to prepare the driving force corresponding to the bit signal, so increasing the number of bits causes practical problems. may occur. For example, as shown in Figure 4, for 8 bits, the 256.9th bit is 512, the 10th bit is 1024, and the 15th bit is 2'' = 32768. The driving force is proportional to Bffii (B: magnetic flux density, l effective length of the two-wire ring, j: current flowing through the wire ring). In electrodynamic digital speakers, this Bffii is adjusted to correspond to the focus of the signal. It is clear from the example of a CD player that a signal of at least 12 bits or more is required in order to obtain high-quality playback sound.Assuming a 16-bit signal is used, the positive and negative signs are If we take 1 focus to give , the remaining 15 bits become the element that gives the size, but the first
The focus is O or l, that is, 2 degrees, and the second bit is used at a magnitude of 2', so the maximum value of the driving force is 2'5-
You will have to prepare up to 1.

Conventional thinking suggests that the driving force be weighted using either the same winding on the speaker side and weighted only by the supply voltage, or the same method where the supply voltage is kept constant and weighted only by the winding on the speaker side. It is used. For this reason, in order to correspond to a high-level focus signal, an extremely high voltage is required, and even if one turn of winding is to correspond to one bit signal, a winding of over 30,000 turns is required. 8-bit is said to be the manufacturing limit for speakers driven by digital signals.

(Means for Solving the Problems) The present invention has been proposed in view of the above points, and its purpose is to directly convert a PCM signal into an acoustic signal without digital/analog conversion; Another object of the present invention is to provide a drive method for an electrodynamic planar drive speaker that can reduce the number of signal lines by placing weight on the power supply side as well as the speaker side.

That is, the driving method of the electrodynamic planar drive speaker according to the present invention includes a diaphragm made of an insulating material having a linear conductor, and a plurality of magnetic poles arranged at a slight interval from the diaphragm, In the driving method of the electrodynamic planar drive speaker, the strip conductor is configured to give weight by changing the length and width of each strip conductor in accordance with a focus signal corresponding to the number of bits of a supplied pulse code modulation signal. The above object is achieved by arranging the weight to be applied to the power supply side in accordance with the bit signal.

(Function) Since the power supply side also bears the weight according to the bit signal, the number of wire conductors on the diaphragm (number of signal lines)
In addition, it becomes possible to directly convert the PCM signal into an acoustic signal without digital/analog conversion.

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

Before describing embodiments of the present invention, an electrodynamic planar drive speaker will first be described.

Figure 1 shows a general electrodynamic planar drive speaker, in which 1 is a diaphragm with a linear conductor 2 provided on a flexible resin film, and 3 and 4 are arranged with a slight spacing from the diaphragm. The permanent magnet is arranged such that adjacent magnetic pole faces with respect to the diaphragm have alternately different polarities. Print molding is carried out on the resin film by photo-etching or by a printing process using conductive printing ink in the same manner as the number of printed wirings.

As shown in FIG. 2, the linear conductor 2 is formed in a zigzag shape with parallel conductor portions.

5.6 is a yoke, and an acoustic hole 7 is provided between the magnetic poles of the yoke 5.6. The broken line indicates the distribution state of magnetic flux.

In such an electrodynamic planar drive speaker, as mentioned above,
Compared to an electrodynamic type having a wire-wound coil, the linear conductor can be formed by print molding, so the length, length, or pattern of the conductor can be arbitrarily determined.

The present invention utilizes the characteristics of the electrodynamic planar drive speaker described above to provide an electrodynamic type that can directly convert a PCM signal into an acoustic signal without digital/analog conversion, and can reduce the number of signal lines. This provides a driving method for a planar drive speaker.

Examples according to the present invention will be described below.

That is, FIG. 3 is an explanatory diagram showing the number of signal lines corresponding to an 8-bit signal in the present invention. ×2 in the figure means that the power supply side provides twice as much current.

The present invention is to reduce the weight of the diaphragm and driving force portion by making the power supply side of a speaker system driven by a digital signal bear a portion corresponding to the number of bits.

The weight distribution ratio is an element that should be considered in the design, and is not specified in this consideration.
Distribute as shown in the table.

As shown in Table 1 and Figure 3, when comparing the area ratio of speakers corresponding to 8 bits with the same ratio, it was found that the area ratio was 511:199, which is about 39% of the size.

On the other hand, in a speaker compatible with 16 bits, this ratio is 131071'l:12871, which is about 9.8%.

In the case of this electrodynamic planar drive speaker drive method, the number of windings, etc. can be reduced by the same ratio, but these effects not only simplify the configuration of the speaker unit, but also
Since the back electromotive force generated in the parts of the wire that are not driven by the signal is reduced, it is becoming safer in terms of counter pressure on the power supply side.

Driving force Bj! To weight i, B, 1. ,
There are three variable elements of i. B and e are determined by the structure of the speaker body, and ■ is determined by the supply voltage and the input impedance of the wire.

The present invention distributes the weight corresponding to the bit signal to the speaker body and the power supply side by setting such variable elements to arbitrary values. It should be noted that there is a degree of freedom in the combination of how to set the three elements.

According to the present invention, the 4-bit SP with weights as shown in FIG. By increasing the signal input by 2, the number of lines can be reduced from 15 to 10.

In the driving method of the electrodynamic planar drive speaker of the present invention, as shown in Table 2, the weight on the power supply side is set to 1 for only 1-bit signals, and 2 for all 2-bit or more signals. , 128 lines for 8-bit SP, and 32,768 lines for 16-bit SP.

Table 2 Also, as shown in Table 3, the 1-bit signal is 1.2 to 8
If we input the number x2 and the number above it x4, there will be 64 trees for an 8-pin signal and 16,338 trees for a 16-bit signal.

Table 3 Furthermore, as shown in Table 4, 1 to 4 bit signals are 1.
5-8 bit signal x2.9-12 bit signal x4.
13-16 bit signal x 8.17 bit signal x 16
If you input it, 71 lines for 8 bits and 463 lines for 16 bits
There will be 9 pieces. In both directions, one bit was used for the code.

Table 4 (Effects of the Invention) As described above, the electrodynamic planar drive speaker according to the present invention has a diaphragm made of an insulating material having a linear conductor, and a plurality of diaphragms arranged at slight intervals from the diaphragm. In an electrodynamic planar drive speaker having a magnetic pole of As a result, the PCM signal can be directly converted into an acoustic signal without digital/analog conversion, and the number of signal lines can be reduced by placing the weight not only on the speaker itself but also on the power supply side. can be reduced.

[Brief explanation of the drawing]

FIGS. 1 and 2 are a cross-sectional view and a plan view illustrating a general electrodynamic planar drive speaker, FIG. 3 is an explanatory diagram showing the driving method of the electrodynamic planar drive speaker of the present invention, and FIG. FIG. 7 is an explanatory diagram showing the area ratio of a diaphragm corresponding to a focus signal in a conventional electrodynamic planar drive speaker drive method. 1... Vibration plate 2... Linear conductor 3.4...
Permanent magnet 5.6... Yoke 7... Acoustic hole Figure 1 Figure 2 Figure 3 X2 X2 Figure 4

Claims (1)

[Claims] comprising a diaphragm made of an insulating material having a linear conductor, and a plurality of magnetic poles arranged at slight intervals from the diaphragm,
In the driving method of the electrodynamic planar drive speaker, the linear conductor is configured to change the width of each of the linear conductors and give weight according to a bit signal corresponding to the number of bits of a supplied pulse code modulation signal. A drive method for an electrodynamic planar drive speaker characterized in that weight is distributed and borne by both the speaker body and a power supply unit according to a bit signal.