JP2007282039A - Electromagnetic transducer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve ideal sound pressure/sound quality without decreasing the area of a magnetized portion in a permanent magnet plate by preventing vibration from colliding with a portion other than air holes, and effectively utilizing the range of a non-magnetized zone nz. <P>SOLUTION: An electromagnetic transducer comprises permanent magnet plates 2, 5 each formed with a band-like multi-pole magnetization pattern and frames 1, 6 for covering and supporting the permanent magnet plates 2, 5 and air holes of the permanent magnet 2 and the frame 1 are slit-shaped. Thus, effects can be provided that vibration is prevented from colliding with a portion other than the air holes 8 and ideal sound pressure/sound quality can be improved without decreasing the area of a magnetized portion. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electromagnetic transducer for reproducing an audio signal, for example.

Various technologies have been proposed for electromagnetic transducers combining a permanent magnet and a vibrating membrane. FIG. 4 is a diagram showing a schematic diagram of the configuration of a conventional flat-plate electromagnetic transducer. This type of electromagnetic transducer is usually composed of permanent magnet plates 2, 5, a vibrating membrane 4 disposed so as to face the permanent magnet plates 2, 5, and the permanent magnet plates 2, 5 and the vibrating membrane 4. A shock-absorbing member 3 disposed between them and frames 1 and 6 covering them are provided. The vibrating membrane 4 has a coil 7 having a coil pattern 7 a formed on the entire surface, and the frame 1 and the permanent magnet plate 2 have circular air holes 10.
FIG. 2 is a cross-sectional view of a flat electromagnetic transducer, which includes permanent magnet plates 2 and 5 and a vibrating membrane 4 disposed so as to face the permanent magnet plates 2 and 5. The permanent magnet plates 2 and 5 have parallel striped multi-pole magnetized patterns in which strip-like N poles and S poles appear alternately. The permanent magnet plates 2 and 5 have a so-called non-magnetized portion (magnetized neutral zone) nz in a gap portion between different magnetic poles. The vibrating membrane 4 forms a coil 7 at a position facing the unmagnetized portion nz, and the frame 1 and the permanent magnet plate 2 have circular air holes 10 as shown in FIG.

  In this electromagnetic transducer, when a current (audio signal) flows through the coil 7 of the vibration film 4, the coil 7 and the strip-shaped multipolar magnetization pattern of the permanent magnet plates 2 and 5 are electromagnetically coupled. Audio vibration) is generated in the diaphragm 4 by Fleming's law. This vibration passes through the circular air holes 10 (openings) of the frame 1 and the permanent magnet plate 2, and sound is output to the outside in the direction in which the frame 1 and the permanent magnet plate 2 exist.

Japanese Patent Laid-Open No. 9-331596 (paragraph 0013)

  The conventional electromagnetic transducer is configured as described above, and the vibration generated from the vibrating membrane passes through the air hole and the sound is output to the outside, so the shape of the air hole matches the shape of the unmagnetized part nz. Need to be arranged. However, the shape of the circular air hole was often used as the air hole of the frame or the permanent magnet plate in the conventional cone-shaped speaker, but it can be arranged to match the shape of the unmagnetized part nz. However, the vibration collides with a portion other than the air hole. For this reason, the range (area) of the unmagnetized portion nz cannot be used effectively, and the sound is difficult to be transmitted to the outside. Further, in order to prevent vibrations from colliding with parts other than the air holes, when the shape of the circular air hole is made larger than the width of the unmagnetized part nz, the magnetized part of the permanent magnet plate is reduced, so that the permanent magnet There was a problem that the magnetic force of the plate was lowered, and as a result, the sound pressure was lowered.

  In order to solve the above problems, the present invention prevents vibrations from colliding with parts other than the air holes, effectively uses the range of the unmagnetized part nz, and the permanent magnet plate reduces the area of the magnetized part. It aims to improve ideal sound pressure / sound quality without reducing it.

  An electromagnetic transducer according to the present invention is an electromagnetic transducer comprising a permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed, and a frame that covers and supports the permanent magnet plate. The permanent magnet plate and the frame are slit-shaped. Air holes.

  An electromagnetic transducer according to the present invention is an electromagnetic transducer including a permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed, and a frame that covers and supports the permanent magnet plate. Since the shape is a slit shape, vibrations are prevented from colliding with parts other than the air holes, and the permanent magnet plate having the slit-like air holes can effectively utilize the range of the unmagnetized part nz. Ideal sound pressure / sound quality can be improved without reducing the area of the magnetized part.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram of a flat electromagnetic transducer configuration according to Embodiment 1 of the present invention. This electromagnetic transducer is disposed between the permanent magnet plates 2, 5, the diaphragm 4 disposed so as to face the permanent magnet plates 2, 5, and between the permanent magnet plates 2, 5 and the diaphragm 4. The shock absorbing member 3 and the frames 1 and 6 for covering and supporting them are provided, and the vibrating membrane 4 forms a coil 7 having a meandering coil pattern 7a on the entire surface. This is the same as the conventional electromagnetic transducer, but the air holes 8 of the frame 1 and the permanent magnet plate 2 have a slit shape, unlike the conventional circular shape.
The cross-sectional view of the electromagnetic transducer according to the first embodiment is shown in FIG. 2 in the same manner as the conventional electromagnetic transducer. The electromagnetic transducer is provided on the permanent magnet plates 2 and 5 and the permanent magnet plates 2 and 5. The diaphragms 4 are arranged so as to face each other, and the frames 1 and 6 cover them. The permanent magnet plates 2 and 5 each have a strip-like multipolar magnetization pattern in which different magnetic poles are alternately formed at a predetermined interval. The permanent magnet plates 2 and 5 have a so-called unmagnetized portion nz of a gap portion between different magnetic poles. The vibration film 4 forms a coil 7 at a position facing the unmagnetized portion nz, and the frame 1 and the permanent magnet plate 2 have slit-shaped air holes 8 as shown in FIG.

  First, as shown in FIG. 2, the permanent magnet plates 2 and 5 are formed on one side with strip-shaped multipolar magnetization patterns N and S made of sintered ferrite magnets on almost the entire surface facing the vibration film 4. As shown in FIG. 3 to be described later, the multipole magnetization patterns N and S are parallel striped multipole magnetization patterns in which strip-like N and S poles appear alternately, The permanent magnet plate 2 is provided with a plurality of slit-like air holes 8 having the same width as the unmagnetized portion nz at a constant pitch a along the unmagnetized portion nz.

  Next, as shown in FIG. 1, the vibrating membrane 4 has a coil 7 having a meandering coil pattern 7a formed on the surface thereof, and as shown in FIG. 2, the vibrating membrane 4 faces the permanent magnet plates 2 and 5. It is arranged. The linear portion of the coil 7 is arranged at the center of the strip-shaped N pole and S pole of the multipolar magnetization pattern, and the linear portion of the coil 7 is disposed in parallel at the same pitch as the strip-shaped magnetic poles N and S. ing. The vibration film 4 has a structure in which a coil 7 having a meandering coil pattern 7a is printed on a flexible thin film resin film.

  The buffer member 3 is formed of a non-woven fabric having air permeability and acoustic energy permeability. As shown in FIG. 1, the buffer member 3 is disposed between the permanent magnet plates 2 and 5 and the vibration film 4 and vibrations thereof. The membrane 4 prevents the permanent magnet plates 2 and 5 from colliding with each other during vibration and plays a role as a suspension.

  The frame 1 has slit-shaped air holes 8 that communicate with the slit-shaped air holes 8 of the permanent magnet plate 2. The frame 6 is disposed on the surface of the permanent magnet plate 5 opposite to the surface on which the multipolar magnetized pattern is formed to prevent leakage of magnetic flux. For the frames 1 and 6, for example, an iron plate, a nickel / iron alloy (permalloy) plate, or the like is applied.

  FIG. 3 is a schematic diagram for explaining the effect due to the difference in shape of the air holes 8 and 10 of the electromagnetic transducer. 3A is a diagram showing the arrangement of the slit-shaped air holes 8 in the frame 1 and the permanent magnet plate 2, and the slit-shaped air holes 8 are formed at intervals of a pitch a. FIG. 3 (a) is a diagram showing the magnetization pattern 9 of the permanent magnet plate 2, which is a parallel striped multipolar magnetization pattern in which N poles and S poles appear alternately at a pitch a. An unmagnetized portion nz is provided in a gap portion between different magnetic poles. FIG. 3A is a diagram in which the slit shape of the air hole 8 is arranged so as to match the shape of the non-magnetized portion nz of the permanent magnet plate 2. 3B is an illustration showing the arrangement of the circular air holes 10 in the frame 1 and the permanent magnet plate 2. The conventional circular air holes 10 are formed at intervals of a pitch a. . The lower diagram of FIG. 3B is the same as the lower diagram of FIG.

  In FIG. 3B, the frame 1 and the permanent magnet plate 2 have circular air holes 10 with respect to the straight unmagnetized portion nz, so the shape of the unmagnetized portion nz and the shape of the air holes 10 are illustrated. As shown in the upper and lower views of FIG. 3B, the vibrations collide with parts other than the air holes 10, the range of the unmagnetized part nz cannot be used effectively, and the vibrations are not sufficiently transmitted to the outside. . Further, in order to effectively utilize the range of the unmagnetized portion nz, when the diameter of the circular shape of the air hole 10 is made larger than the width of the unmagnetized portion nz, the opening portions of the frame 1 and the permanent magnet plate 2 are shown in FIG. As a result, the permanent magnet plate 2 has a smaller magnetized area and a lower magnetic force. As a result, the output sound pressure level is lowered.

  On the other hand, in FIG. 3A, the frame 1 and the permanent magnet plate 2 have a plurality of slit-like air holes 8 having the same width as the unmagnetized portion nz at a constant pitch a along the unmagnetized portion nz. Therefore, the shape of the unmagnetized portion nz matches the shape of the air hole 8, and the range of the unmagnetized portion nz can be used effectively. For this reason, vibrations are prevented from colliding with portions other than the air holes 8, and the permanent magnet plate 2 has an effect that ideal sound pressure / sound quality can be improved without reducing the area of the magnetized portion.

  Further, since the frame 1 can widen the slit-like air hole 8 to within the allowable strength range, the frame 1 can effectively utilize the unmagnetized portion nz within the openable range. This means that the permanent magnet plate 2 has a plurality of slit-like air holes 8 having the same width as the non-magnetized portion nz at a constant pitch a along the non-magnetized portion nz, and the frame 1 is not magnetized. It is also possible to have a plurality of slit-like air holes 8 having a width wider than that of the unmagnetized portion nz at a constant pitch a along the portion nz.

Next, the operation will be described.
When an electric current flows through the coil 7 of the meandering coil pattern 7a formed on the surface of the vibration film 4, the coil 7 and the strip-shaped multipolar magnetization pattern of the permanent magnet plates 2 and 5 are electromagnetically coupled, Is generated in the vibration film 4 by Fleming's law. This vibration passes through the slit air hole 8 of the frame 1 and the permanent magnet plate 2, and sound is output to the outside from the direction of the slit-shaped air hole 8. The slit-shaped air holes 8 are arranged at a constant pitch a along the unmagnetized portion nz of the permanent magnet plate 2 with the same width as the unmagnetized portion nz, so that the shape of the air holes 8 is not magnetized. Since it matches the shape of the portion nz, the range of the unmagnetized portion nz can be used effectively, and the permanent magnet plate 2 can improve the ideal sound pressure / sound quality without reducing the area of the magnetized portion. The permanent magnet plates 2, 5, the vibrating membrane 4, and the buffer member 3 are covered with the frames 1, 6 and attached to the speaker housing.

  According to the first embodiment described above, the electromagnetic transducer includes the permanent magnet plates 2 and 5 on which the strip-shaped multipolar magnetization pattern is formed, and the frames 1 and 6 that cover and support the permanent magnet plates 2 and 5. And the shape of the slit-shaped air hole 8 of the permanent magnet plate 2 and the frame 1 matches the shape of the non-magnetized part nz of the permanent magnet plate 2, so that vibrations collide with parts other than the air hole 8. The permanent magnet plate 2 has the effect that the ideal sound pressure / sound quality can be improved without reducing the area of the magnetized portion, and has the effect that the range of the unmagnetized portion nz can be effectively used. Has the effect of being easily transmitted to the outside.

1 is a schematic diagram of a configuration of a flat-plate electromagnetic transducer according to Embodiment 1. FIG. It is a figure showing the cross section of a flat type electromagnetic transducer. It is a figure which shows the effect by the difference in the shape of an air hole. It is the schematic of the conventional flat type electromagnetic transducer structure.

Explanation of symbols

  1 frame (upper part), 2 permanent magnet plate (upper part), 3 buffer member, 4 diaphragm, 5 permanent magnet plate (lower part), 6 frame (lower part), 7 coil, 7a meander coil pattern, 8 slit-shaped air hole , 9 Magnetized pattern, 10 circular air holes, nz unmagnetized portion (neutral neutral zone), a pitch.

Claims (2)

In an electromagnetic transducer comprising a permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed, and a frame that covers and supports the permanent magnet plate,
The electromagnetic converter, wherein the permanent magnet plate and the frame have slit-shaped air holes.   2. The electromagnetic transducer according to claim 1, wherein in the permanent magnet plate and the frame, a shape of the air hole matches a shape of an unmagnetized portion of the permanent magnet plate.

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