Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS498889 ■ Electrostatic Speaker Referral No. 45-5424 @ 峙 [39-4357 [Phase] Application No. 39 (1964) January 29 @ Inventor Tokohira Tai yokohama, Kohoku Ward Kono Ward, Yokohama Prefecture 880 Matsushita Telecommunications Industry Co., Ltd. Domi Do Yoshida same place 0 applicant Matsushita Electric Industrial Co., Ltd. Kadoma city Oji Kamon 1006 [phase] agent patent attorney Toshio Nakao 1 person outside BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1 to 6 show specific examples of the electrostatic speaker used in the present invention, and FIG. 1 shows a variation of the effective area of the electrode facing the diaphragm, FIG. 2 shows different electrode spacings, FIG. 3 shows distribution of voltage to a large number of divided fixed electrodes, FIG. 4 shows changed effective dielectric constant between electrodes, FIG. 5 shows FIG. Instead of what is shown in FIG. 1, a number of holes are made in the fixed electrode and the effective area is changed by changing the density of the holes, and in FIG. 6, the size of the holes is also changed. FIG. 7 is a characteristic diagram of the conventional electrostatic speaker, FIG. 8 is a diagram showing an embodiment of the electrostatic speaker according to the present invention, and FIG. 9 is a characteristic diagram of FIG. FIGS. 13 and 14 show an embodiment for detecting the amplitude of the vibrator in FIG. Detailed Description of the Invention The present invention detects the displacement, velocity or acceleration of a vibrating body in an electrostatic speaker and dynamically feeds it back to the input end of a drive amplifier to control the vibration and obtain stable vibration over a wide frequency range. The conventional electrostatic speaker which is intended to have the characteristics shown in FIG. 7 is put to practical use mainly for high-pitched sound reproduction [111111]. That is, since the characteristic becomes almost flat as shown in the figure at the frequency of KA = 1 or more, only the frequency range of KA = 1 or more has been practically 04-05-2019 1 used. (However, S in FIG. 1 is the effective stiffness of the vibrator, m is the substantial amount, s / m is its natural frequency, ffK is 2πfc, f is the frequency, C is the speed of sound, and A is the equivalent radius. The present invention is an improvement of such an electrostatic speaker, and as is well known, the electrostatic driving force applied to each portion of the movable electrode or vibrating film in the electrostatic speaker is mainly on each portion on the film surface. The vibrating membrane itself has a distribution of the driving force applied to each portion on the vibrating membrane surface using the relative positional relationship with the corresponding fixed electrode, that is, the driving electrode and the fact that it is determined by the potential difference between both electrodes By making the vibration mode of free vibration displacement correspond to or approximate to the form of the function to be changed, that is, the standard function, it is made to vibrate in the same vibration mode over a wide frequency band, and its vibration amplitude is detected To provide an electrostatic speaker characterized in that its radiation characteristics are controlled by dynamic feedback to the electrostatic speaker. A description will be given below by way of an example shown in the drawings. FIG. 1 is a crosssectional view of a circular electrostatic speaker, in which 1 is a vibrating electrode composed of a homogeneous vibrating film, 2 is an insulator (for example, resin such as epoxy resin or phenol resin), 3 is provided on insulator 2 And a plurality of fixed electrodes, each of which is electrically connected and has the same potential. The fixed electrode 3 is a concentric ring, and the width (radial direction) of the pressure electrode, which has a fixed gap each, becomes narrower toward the periphery. Since all of these electrodes are at the same potential, when focusing on an arbitrary point of the film, the effective area of the opposite fixed electrode is small at the periphery and large at the center. As is well known, the reference function of the circular vibrating membrane is proportional to the Bessel function of the first kind and is Jo (ctl-) in a simple form. However, α1 = 2.405, r: distance from center, [111111] EndPage: 1a: radius of film. Now, since it is proportional to the effective area of the electrode facing the electrostatic drive force, the diaphragm is driven using this electrode by approximating the effective area to Jo (.alpha.1L). Only vibration modes which are of the function Jo (α1-) are allowed. Therefore, within the approximate range, the distribution of vibration displacement at all frequencies is the same, and only one proportional to the Bessel function Jo (.alpha.1-) can be used as the vibration mode. Also, instead of distributing the conductor on the insulator, even if the effective area is changed by distributing many dL to the conductor plate, or even if the fixed electrode is provided with irregularities to distribute the rate of change of the capacitance, The vibration form can be obtained, and the vibration form can be easily obtained by the trigonometric function as described above for the rectangular as well. Furthermore, in this vibration mode, the phase relationship on the surface of the vibrating film vibrates independently of the frequency. Therefore, the vibration film reference frequency is completely equal to that of a single-resonance system having a resonance frequency, and an extremely wide-band piston-like diaphragm, which has been considered to be extremely difficult in the past, can be realized with equal constraints. There is also an embodiment as shown in FIGS. 2 to 4 as a method of 04-05-2019 2 distributing the driving force. That is, FIG. 2 shows a conductor in which the electrode gap is formed so that the fixed electrode 3 has a force coefficient distributed in the form of JO (ctIL), and FIG. 3 shows one in which a DC voltage E is distributed to the divided electrodes 3. In addition, holes 5L 52, 53 having different densities or diameters of the holes 4 provided in the fixed electrode 3 as shown in FIGS. It is possible to give the same effect as that described above by distributing. In FIG. 3, R is a resistive divider. As described above, according to the present invention, the driving force distribution neglecting the vibration characteristic of the vibrator as in the prior art, for example, the drawbacks such as uniform driving all over the surface or driving of concentrated points A so-called divided vibration or high-order vibration does not occur to cause unevenness on the frequency characteristics, so that an extremely monotonous electroacoustic transducer having characteristics as shown in FIG. 7 can be realized. The above description relates to the structure of the speaker itself that is a part of the present invention, and may be completed by configuring the system described below as one component of the present invention or more. The present invention will now be described by way of an embodiment shown in the drawings. FIG. 8 is a principle view thereof, and 1 is a circular vibrating body consisting of a vibrating electrode or a vibrating film and the periphery of the vibrating film 10 is fixed by a fixing frame 3 There is. Reference numeral 2 denotes a vibrating electrode, which collectively describes those having the characteristics described above, and drives the vibrating body 1 by the output of the drive amplifier 7 obtained by amplifying the DC power supply 9 and the AC signal 8. A detection electrode 4 is provided in the vicinity of the vibrating membrane 1 so that the vibration amplitude of the vibrating membrane 1 can be detected. Reference numeral 6 denotes a feedback amount setting circuit, which amplifies the output from the detection electrode 4 by the amplifier 6 and then adds it to the drive amplifier 7. Further, since the drive amplifier 7 is also driven by the AC input signal 8, a dynamic feedback is constituted as a whole, and this feedback amount is appropriately set according to the characteristics of the vibrating body 1. As shown in FIG. 9, an electrostatic speaker which can be used over a very flat wide band can be obtained. This is in the same form as dynamic feedback that is generally performed in the past, but as a drawback of the conventional case, the dynamic feedback is limited to only a very limited bass range, for example, 300 Hz or less, because the vibration mode of the diaphragm differs depending on the drive frequency. In the present invention, as described above, the range of dynamic feedback is extended to, for example, about 3000 Hz because the vibration mode is the same at all frequencies as described above, and the characteristic of the feedback system is high. A speaker with excellent stability, low distortion, etc. is realized. The detection can be easily obtained by applying the method shown in FIGS. 10 to 13 to the detection of the amplitude of the vibrator 1 in FIG. That is, in FIG. 10, the detection electrode 4 is provided around the drive electrode 20, and as one of the features of the present invention, this portion is detected by utilizing the fact that the peripheral portion of the diaphragm does not give a driving force. 11 uses the detection electrode 4 inserted in the hole of 04-05-2019 3 the drive electrode 2 provided with a plurality of holes 13, and FIG. 12 shows the piezoelectric material or the piezoelectric material in the periphery of the vibrator 1 12 detects a change in film tension corresponding to the vibration amplitude, and FIG. 13 shows an amplitude modulation using the high frequency power supply 15 using the change in electrostatic capacitance between the vibrator 1 and the drive electrode 2 Alternatively, the high frequency power supply 15 is frequency modulated by the change of the electrostatic capacity between the vibrating body 1 and the drive electrode 2 by phase modulation. EndPage: 2 The amplitude detected by each of these methods is amplified by the amplifier 5 and applied to the drive pulse width I through the feedback amount setting circuit 6. (However, in FIG. 8 and FIG. 10, 10 is a DC blocking capacitor, 11 is a protection resistor, 14 is a resonant coil, 16 is a high frequency cold ring, 17 is a rectifier, and 18 is a low frequency blocking capacitor. As described above, according to the present invention, unlike the general electrostatic speaker having the characteristics as shown in FIG. 7, since the vibration mode of the vibrating body is constant regardless of the frequency, high-order divided vibration There is no instability, etc., and by applying appropriate dynamic feedback, as shown in FIG. 9, it is possible to reproduce the characteristics extremely flat and always stable over a wide band. 04-05-2019 4
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