JPS6029278Y2 - flat speaker - Google Patents

Description

[Detailed Description of the Invention] This invention relates to an improvement of a flat plate speaker using a diaphragm on a flat plate.

A flat speaker with a flat diaphragm has a narrower piston vibration range than a cone type speaker, but because the diaphragm is a flat plate, the peaks and dips in the sound pressure-frequency characteristics, which are problems with cone type speakers, do not appear and the phase does not appear. -There is an advantage that a flat frequency characteristic can be obtained.

Furthermore, structural improvements such as using a honeycomb structure that is lightweight and can increase thickness as a diaphragm, and obtaining materials with a large Young's modulus make the piston vibration area comparable to that of a cone-type speaker. Recently, it has started to be reconsidered.

In addition, because the diaphragm is flat, the primary resonance frequency is lower than that of a cone-shaped speaker, and the primary divided vibration appears.
In order to reduce this, a method is used in which the nodes of the primary division vibration of the diaphragm are driven by the voice coil.

This creates a new problem: a cavity is created in the area surrounded by the diaphragm, voice coil, and upper plate, and cavity resonance occurs in this area, causing performance deterioration.

This invention was devised in view of the above-mentioned problems, and the details of this invention will be explained below with reference to the illustrated embodiments.

That is, in FIG. 1, 1 is a hollow disc-shaped lower plate 2 is also a hollow disc-shaped upper plate, 3 is a cylindrical magnet that is in contact with and fixed between the upper plate 2 and the lower plate 1, and 4 is a hollow disc-shaped lower plate. A cylindrical yoke whose upper inner peripheral side has an appropriate gap with the outer peripheral side of the plate 2 and whose lower part is fixed in contact with the lower plate constitutes a magnetic circuit.

As shown in detail in FIG. 2, reference numeral 5 denotes a hollow disc-shaped support part 6, a hollow disc-shaped support part 7, and a fixing part 7 whose inner circumferential side is fixed to the outer circumferential side of the yoke 4. An outer frame 9 consisting of a plurality of angle parts 8 each integrated with the support part 6 is a cylindrical inner frame with a flange, and 13 is a cylindrical frame provided in the gap between the plate 2 and the yoke 4. The voice coil 14 is a hollow disk-shaped spider with a corrugated cross section that fixes the voice coil 13, and the end thereof is attached to the support 1 provided on the fixing part 7 of the frame 5.
It is fixed at 5.

Reference numeral 16 denotes a flat diaphragm in the form of a hollow disc, and its outer peripheral end is fixed to the outer frame 5 by an outer edge 17, and its inner peripheral end is fixed to the inner frame 9 by an inner edge 18.

The voice coil 18 is fixed to this diaphragm at the node of its primary axis-symmetric divided vibration.

19 and 20 are gaskets for fixing the outer edge 17 and the inner edge 18 to the outer frame 5 and the inner frame 9, respectively; 21 is a frame of a treble speaker fixed to the inner frame; 22 is a sound output from an amplifier; This is a lead wire for inputting a signal to the voice coil 13.

FIG. 3 is a partial perspective view showing the details of the voice coil 13, which is the main point of this invention. A plurality of rows are provided at predetermined intervals on the peripheral wall thereof.

In the flat speaker configured in this way, an audio signal from the amplifier is inputted to the voice coil 13 from the lead wire 22, and the voice coil 13 performs a piston movement according to the audio signal. Vibration plate 1
6 is driven.

By the way, in this speaker, since the voice coil 13 drives the nodes of the primary axisymmetric divided vibration of the diaphragm 16, the primary divided vibration can be greatly reduced. If the bobbin 23 of the voice coil 13 were not provided with a plurality of small round holes 24, the space surrounded by the coil 13 and the upper plate 2 would be almost sealed, and cavity resonance would occur in this area, deteriorating the performance. Furthermore, since the stiffness of the air in this cavity is added to the stiffness of the diaphragm support system, the low resonance frequency increases and damping is applied, which is unfavorable in terms of sound quality.

For this reason, in this invention, a plurality of small round holes 24 for air venting are provided in the bobbin 23 of the voice coil 13, and the air in the hollow portion is released from the small round holes 24 to the outside via the outer frame 5.

By doing this, cavity resonance can be prevented, and
The influence of stiffness of the air in the cavity can be reduced, and performance deterioration due to the cavity can be prevented.

Furthermore, in this design, the air vent hole is located at the voice coil 13.
Since the hole is formed into a small round shape on a straight line in the same direction as the driving direction, it is possible to suppress a decrease in the strength of the voice coil 13 due to this hole as much as possible.

In the above embodiment, a hollow disc-shaped diaphragm is used, but the diaphragm is not limited to a hollow disc-shaped diaphragm, and can be surrounded by a flat diaphragm, a voice coil, and an upper plate of a magnetic circuit. The present invention can be applied to any flat plate speaker that creates a closed space.

As mentioned above, this invention uses a flat plate-like diaphragm, and in a flat-plate speaker in which the nodes of the primary division vibration of this diaphragm are driven by a voice coil, the voice coil bobbin is connected to a straight line in the same direction as the driving direction of the voice coil. Multiple small round holes are provided on the top, and multiple rows of these small holes are arranged, so
It suppresses the decrease in the strength of the voice coil as much as possible and removes the air from the surrounding space formed on the back side of the flat diaphragm, preventing cavity resonance and over-damping in that space, resulting in a high-performance speaker. It will be done.

[Brief explanation of drawings]

FIG. 1 is a vertical sectional view of the right half of a flat speaker showing an embodiment of this invention, FIG. 2 is a perspective view of a reduced portion of the outer frame, and FIG. 3 is a partial perspective view of the voice coil. In each figure, the same reference numerals indicate the same or equivalent parts. 1 is the lower plate 2 is the upper plate 3 is the magnet 4 is the yoke 5 is the outer frame 9 is the inner frame 13 is the voice coil 16 is the diaphragm 17 is the outer edge 18 is the inner edge 23, the bobbin 24 has a small round hole.

Claims (1)

[Scope of utility model registration request] By using a flat diaphragm and driving the axially symmetrical division vibration nodes of this diaphragm with a voice coil equipped with a cylindrical bobbin, the diaphragm is surrounded by the diaphragm, the bobbin, and the upper plate of the magnetic circuit, and is almost sealed. A plurality of small round holes are provided in the bobbin of the voice coil on a straight line in the same direction as the driving direction of the voice coil, and a plurality of rows of small round holes are arranged at predetermined intervals on the peripheral wall of the speaker. A flat plate speaker characterized by: