JPS60176398A - Electromagnetic driver - Google Patents

Abstract

PURPOSE:To improve substantially a distortion component of sound pressure reproduced by a front panel by adapting a symmetric construction in which one magnetic gap is enlarged when the other one is narrowed with respect to a vertical movement of a diaphragm. CONSTITUTION:Two diaphragms 18a and 18b are arranged so that the equal magnetic gaps lg1 and lg2 will be formed between two opposite exciting parts, and two types of static electricity attraction force caused by permanent magnets 8a and 8b cancel out each other and turn out zero. As a result, stress to a suspension 20 totally disappears. When electrical signals are added to exciting coils 7a and 7b, magnetic force acting to the diaphragms 18a and 18b supported by the suspension 20 in the condition of zero stress through spacers 19a and 19b changes in accordance with a signal current passing in the coils, and one diaphragm acts upon static electricity attraction force to be strengthened and the other acts upon it to be weak. The difference between two types of magnetic force acts upon a front panel 3 as drive force and is reproduced as an acoustic output.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention provides a drive driver in a part of the housing of an audio equipment such as a television or a cassette recorder with a radio, and reproduces sound by vibration of the housing. This invention relates to a speaker driver of this type.

Conventional configurations and their problems In recent years, the shapes of audio equipment such as televisions and cassette recorders with radios have become significantly more compact.

Here, we will focus on the TV SENO and discuss its problems.One of the factors that hinders miniaturization is the shape of the speaker. For this reason, efforts have been made to use rectangular speakers with a good space factor, or to attach the speakers to the sides of the centrifuge.

However, even if the speaker shape is rectangular, there is a limit to how compact it can be made because space for the speaker chamber is required in the front of the set. In addition, when a speaker is mounted on the side of the center, the sound pressure characteristics of the speaker are directional, so the high-frequency sound pressure will drop significantly at locations outside the front axis of the speaker, at the knob, and in front of the center, resulting in poor sound quality. There was a problem with deterioration. Furthermore, the method of mounting the speaker on the side has the disadvantage that if there is an obstacle on the side, sound reproduction becomes difficult to reproduce, and the installation location of the set is limited.

In order to solve these problems, a playback method was devised in which a driver is attached to the front panel of the cathode ray tube that makes up the set, vibrates it, and the front panel is used as a diaphragm.

A conventional speaker of this type will be explained below.

Figure 1 is a perspective view of a television set that uses this type of speaker. 1 is a cabinet, 2 is a cathode ray tube,
3 is a front panel made of a material with high light transmittance, such as glass or transparent acrylic, which is attached to the front of the cathode ray tube 2; 4 is an electromagnetic driver attached to the back of the front panel 3;

FIG. 2 shows a structural diagram of the electromagnetic driver, FIG. 2(a) is a plan view thereof, and FIG. 2(Φ) is a sectional view of the same structure. In FIG. 2, 5 is an excitation coil that is integrally or mechanically connected to the plate 6. 7 is an excitation coil wound around the center pole 5, and 8 is a ring-shaped permanent magnet placed on the plate 6. , constitutes an excitation section. Reference numeral 9 indicates an outer peripheral cover made of a non-magnetic material that is fixed to the bottom surface of the plate 6 and wraps around the outer periphery of the permanent magnet 8. Reference numeral 10 indicates a diaphragm made of a ferromagnetic material such as soft iron. It is fixed to the component 13 with screws 14. Further, the outer peripheral portion of the suspension 12 is fixed to the upper surface of the outer peripheral cover 9 by screws 16 via a spacer 15, and the diaphragm 12 is arranged with a predetermined gap between it and the excitation section.

Vibration component 13 of the drive driver composed of the above components
The upper surface of is firmly fixed to the front panel 3 of the television set shown in FIG. 1 with adhesive or the like.

The operation of a television speaker configured using the conventional electromagnetic driver configured as described above will be described below.

In the above-mentioned type of speaker, an electromagnetic driver is attached to the front panel 3 of the television set, and the drive force of the electromagnetic driver causes the front panel 3 to vibrate to reproduce sound.

That is, the magnetic force acting on the diaphragm 10 held by the suspension 12 changes in response to the signal current flowing through the excitation coil 7, and this magnetic force generates a driving force on the diaphragm 10. The driving force generated in the diaphragm 10 is transmitted to the oscillating component 13 via the spacer 11 provided on the top of the diaphragm 10, causing the front panel 3 to vibrate. front panel 3
Since it covers the front surface of the cathode ray tube 2, it has a wide vibration area and can efficiently convert the driving force of the electromagnetic driver into acoustic output. Furthermore, compared to conventional electrodynamic speakers, the electromagnetic driver does not require a voice coil, which is a moving part, so it has a simpler structure and can be manufactured at a lower cost.

However, in the configuration of the electromagnetic driver described above, a magnetic force is generated in the diaphragm 10 by an electric signal, and the diaphragm 10 moves up and down to apply a driving force to the front panel 3. At the same time, the magnetic gap between the diaphragm 10 and the excitation section changes every moment. As is well known, in electromagnetic transducers, this occurs due to the size of the magnetic gap. @Power is greatly influenced. FIG. 3 shows the relationship between the magnetic gap and the driving force, and the smaller the magnetic gap, the larger the driving force generated in the diaphragm 10. Therefore, the operating characteristic of conventional electromagnetic drivers is that the driving force increases when the diaphragm 10 moves downward, and decreases when it moves upward. For this reason, the driving force applied to the front panel 3 is asymmetrical between the top and bottom, which is a major cause of sound pressure distortion. Further, since the diaphragm 10 is constantly subjected to static attraction by the permanent magnet 8, stress is constantly applied to the suspension 12 that supports the diaphragm 10, making it a material that can withstand long-term use.

It was necessary to pay great attention to the structure and fixing method, and there were also problems with reliability.

Purpose of the Invention The present invention solves the above-mentioned conventional problems by making the vertical driving force of the diaphragm symmetrical, thereby reducing distortion, and reducing the stress caused by the static attraction force acting on the suspension in a steady state. The object of the present invention is to provide an electromagnetic driver with excellent reliability that can withstand long-term use without problems.

Structure of the Invention The present invention comprises an excitation coil, a center pole having a hole in the center, and a ring-shaped permanent magnet arranged on a plate.
a suspension formed by fixing the plates to each other via a ring-shaped spacer having an opening in the center and provided on the bottom surface around each of the plates; and a recess having an opening in the center. Two diaphragms provided in the center; the diaphragm is disposed inside the hole of the center pole and abuts around 141 of the suspension, and the excitation section and the diaphragm are held at predetermined intervals, respectively. comprising a spacer, a connecting member connecting the two diaphragms, the two spacers, and the suspension;
By arranging two excitation parts and the diaphragm to face each other, the vertical driving force generated on the diaphragm is made symmetrical, reducing sound pressure distortion, and in steady state, stress on the suspension due to static attraction force is eliminated. It is possible.

DESCRIPTION OF EMBODIMENTS FIG. 4 shows a structural diagram of an electromagnetic driver according to an embodiment of the present invention, and FIG. 4(a) is a sectional view of the same structure.
FIG. 4(b) is a sectional view taken along line I-It in FIG. 4(a). In FIG. 4, the same parts as in the conventional example shown in FIG. 2 are given the same numbers. 17a in FIG.

17b is played with a center pole with a hole in the center)
6a, 6b integrally or mechanically connected. 7a,
7b is an excitation coil wound around the center poles 17a and 17b; 8a and 8b are play coils) 6a.

A ring-shaped permanent magnet arranged on the plate 6b constitutes two excitation parts facing each other on the surfaces of the plates 6a and 6b. 18a and 1sb are diaphragms with a recessed portion having an opening in the center;
P is fixed to the suspension 20 via screws 21 and nuts 22 via b. Suspension 2 for Sarah
The outer periphery of the plate 6a, 6b is fixed with an adhesive or the like via ring-shaped spacers 23a, 23b as fixing parts provided on the peripheral bottom surface of the plates 6a, 6b, and the diaphragms 18a, 18b are connected to the two excitation parts. A predetermined gap Xg1. X. 2 are arranged.

Further, the upper surface of the photographing plate 18a is firmly attached to the front panel 3 of the television set.

The operation of the electromagnetic driver of this embodiment configured as described above will be described below.

The two diaphragms 18a, 18b have an equal magnetic gap 2g1. A92 is provided and arranged. Therefore, the static attraction forces by the permanent magnets 8a and 8b cancel each other out and become ○, and in a steady state where there is no drowsiness signal, no stress is applied to the suspension 20 at all. FIG. 6 shows the state of this static suction force. In FIG. 5, A is the static attraction force acting on the diaphragm 18a, B is the static attraction force acting on the diaphragm 18b, and A, B is the static attraction force acting on the diaphragm 18b.
Attraction force C, which is a combination of B, will act. From this figure, it can be seen that in the steady state of Qgl-2g2, the static suction force is ○.

Excitation coils 7a and 7b are connected in series or in parallel and apply electrical signals. In response to the signal current flowing through the excitation coils 7a and 7b, the diaphragm 18 is supported by the suspension 20 in a state of stress O via spacers 19a and 191).
a, the magnetic force acting on 1sb changes. Excitation coil? The signal currents applied to a and 7b are connected so that the magnetic force acting on the diaphragm flows in a direction such that the static attraction force is strengthened on one diaphragm and weakened on the other. This balance difference in magnetic force becomes a driving force, which acts on the front panel 3 and is reproduced as an acoustic output.

As described above, according to this embodiment, the plate 6a.

In FIG. 6b, two opposing excitation sections are provided with diaphragms 18a and 18b, each maintaining the same magnetic gap, and a center pole 17a constituting the excitation section.

A hole is provided in the center of the diaphragm 17b, and both the diaphragms 18a are connected to each other.

The center of plate 18b is connected to the plate 18a by spacers 19a and 19b provided in the holes of plates 6a and 6b.
, υ'-shaped spacer 2 provided on the bottom surface of the periphery of 18b.
The diaphragm 18a is connected via the suspension 20 fixed by 3a and 23b.

When the magnetic gap on one side narrows in response to the vertical movement of 18b, the other widens, so the driving force is also symmetrical, and the distortion component of the sound pressure reproduced from the front panel 3 is greatly increased. It can be improved. In addition, in a steady state where no electric signal is applied, the excitation section and the diaphragm 18
Since the magnetic gaps between the diaphragms 18a and 18b are set to be equal, the static attraction force acting on the diaphragms 18a and 18b is canceled out, eliminating stress on the suspension, making it suitable for long-term use. This makes it possible to realize an electromagnetic driver with excellent durability and reliability.

In the embodiment shown in FIG. 4, the periphery of the suspension 20 was fixed via ring-shaped spacers 23a and 2sb, but as shown in FIG.
The contact surface with the outer periphery is flat, and the area between this outer periphery and the hole of the center pole is tapered (play) 24a, 24'.
It may be fixed directly with b.

Also, screws 2 are used to fix both the diaphragms 18a and Isb.
1 and nuts 22, but they may also be fixed using rivets.

Furthermore, although the magnetization directions of the two permanent magnets 8a and 8b have not been described, they may be magnetized in the same direction or in repelling directions.

Effects of the Invention As described above, the present invention has a symmetrical structure in which when one magnetic gap narrows with respect to the vertical movement of the diaphragm, the other widens, so the driving force becomes symmetrical, for example. By fixing one of the diaphragms to the front panel or the like, the 6-wave component of the sound pressure reproduced from the front panel can be greatly improved. In addition, if the magnetic gaps are made the same in a steady state where no electrical signals are applied, the static attraction force acting on the diaphragm is canceled out, eliminating stress on the suspension, resulting in reliability that can withstand long-term use. This makes it possible to realize an excellent electromagnetic driver, and its effects are impressive.

[Brief explanation of drawings]

Figure 1 is an external perspective view of a television set that uses an electromagnetic driver as a diaphragm on the front panel, Figure 2 (a),
(b) is a structural diagram of the conventional electromagnetic type driver attached to the front panel of Fig. 1, Fig. 3 is a magnetic gap-driving force characteristic diagram of the conventional electromagnetic type driver, and Fig. 4 (a), (
b) is a structural diagram of an electromagnetic driver according to an embodiment of the present invention, FIG. 5 is a magnetic gap-static attraction force characteristic diagram, and FIG.
The figure is a structural diagram of an electromagnetic driver in the embodiment on the same side. 6a, 6b...Plate, 7a, 7b...
・・Exciting coil, s a , s b ・・・・Permanent magnet, 17a, 17b ・・Center pole, 18
a, 18b... diaphragm, 19a, 19b...
... Spacer, 20 ... Suspension, 2
1... screw, 22... oak), 2
3 a +23b...Ring-shaped spacer.

Claims (1)

[Claims] (1) Two excitation parts each having an excitation coil on a plate, a center pole having a hole in the center, a ring-shaped permanent magnet, and an opening in the center; The plates are fixed to each other via a fixing part provided on the bottom surface around the plates, - a suspension, two diaphragms having a recessed part with an opening in the center, and a center pole. a spacer disposed inside the hole and in contact with the periphery of the opening of the suspension to hold the excitation section and the diaphragm at predetermined intervals, respectively; and the two diaphragms and the two spacers. An electromagnetic driver comprising: a connecting member connecting the suspension and the suspension. (2) The electromagnetic driver according to claim 1, characterized in that the gaps between the two excitation parts and the diaphragm are the same. (3) The electromagnetic driver according to claim 1 or 2, characterized in that a ring-shaped spacer is used as the fixing portion. (4) A plate having a flat contact surface with the outer periphery of the suspension and tapered between the outer periphery and the hole of the center pole is used as the fixing portion. The electromagnetic driver according to item 2. (6) A patent characterized in that a screw or nut is used as a connecting member, which has a size that can be stored in a recess provided in the center of the diaphragm, and which passes through an opening in the center of the spacer and suspension. An electromagnetic driver according to claim 1. (6) One of the two diaphragms can be used as a part of a housing of an audio device such as a television or a cassette recorder with a radio, a part of furniture such as a desk or a chest of drawers, or a door. The electromagnetic type driver according to claim 1, wherein the electromagnetic driver is fixed to a part of a building material such as a window or glass. C'7) The electromagnetic driver according to claim 3, characterized in that the ring-shaped spacer around the suspension and the grate are integrally molded. (8) The electromagnetic driver according to claim 5, characterized in that a rivet is used as the connecting member.