JP4964011B2 - Electromagnetic transducer - Google Patents

Description

  The present invention relates to an electromagnetic transducer that is provided with a coil pattern on the surface of a diaphragm and reproduces sound from an audio signal.

In a conventional electromagnetic transducer, a permanent magnet plate and a vibration film are disposed to face each other, and a buffer member is disposed between the permanent magnet plate and the vibration film. These permanent magnet plate, vibration film, and buffer member are covered with a frame or the like, and are attached to, for example, a speaker housing.
For example, an electromagnetic transducer described in Patent Document 1 includes a permanent magnet plate, a vibration film provided at a position facing the permanent magnet plate, a buffer member interposed between the permanent magnet plate and the vibration film, and a permanent vibration film. The permanent magnet plate has a parallel striped multipolar magnetized pattern, and has a single structure in which a number of sound emitting holes are arranged in the neutral zone. The sound emitting holes, which are sound emitting holes, are formed at a constant pitch along the neutral zone. A magnetic field line passes through a position corresponding to the neutral zone of the permanent magnet plate in a direction crossing the linear portion of the coil in the plane of the diaphragm. When a drive current is supplied to the coil, an electromagnetic force is generated in the thickness direction due to the interaction between the current and the magnetic field, and the vibrating membrane vibrates. Sound waves generated by this vibration are emitted to the outside through the sound emission holes, and audio reproduction is performed.

JP-A-9-331596

  Since conventional electromagnetic transducers are configured as described above, it is assumed that sound emission holes are formed at a constant pitch along the neutral zone, and a uniform sound pressure distribution can be obtained on the diaphragm surface. In this case, the sound pressure distribution of the sound radiated from the sound emission hole is also almost uniform on the surface of the electromagnetic transducer. Therefore, in the space, a substantially symmetric sound field is formed in the left-right or up-down direction from the center of the electromagnetic transducer. That is, the maximum sound pressure level can be obtained on the front axis of the electromagnetic transducer on the circumference with a constant radius centered on the center of the electromagnetic transducer in the far field to be formed. In other words, if the axis connecting the center of the electromagnetic transducer and the point where the sound pressure is maximum is the sound axis, and the sound pressure pattern centered on the sound axis is the main lobe, the sound axis and the main lobe are It exists in the front direction.

Here, the sound pressure distribution and directivity characteristics of the conventional electromagnetic transducer will be described in detail. First, FIG. 12 is a front view of an electromagnetic transducer showing an arrangement example of sound emitting holes of a conventional electromagnetic transducer.
The electromagnetic transducer 10 has a length in a longitudinal direction and a direction in which a current flows (hereinafter referred to as a current direction) is about 12 cm, and a length in a short direction and a direction perpendicular to the current direction (hereinafter referred to as an arrangement direction). A rectangle with a length of about 6 cm is formed (however, in FIG. 12, the lengths in the current direction and the arrangement direction are different for explanation). Sound emitting holes 20 are formed at equal intervals in the current direction and the arrangement direction, and 20 holes are provided per row in the current direction and 10 per row in the arrangement direction. In addition, it is assumed that all the sound emitting holes 20 have a diameter of about several millimeters and the sound having the same intensity is emitted.

Next, the sound field simulation result of the conventional electromagnetic transducer 10 is shown. This simulation result is simulated using a model in which the sound emitting holes 20 are arranged on a flat baffle surface in order to approximate a point sound source.
FIG. 13 is a diagram showing a sound pressure distribution of a conventional electromagnetic transducer. If the center in the current direction of the electromagnetic transducer 10 shown in FIG. 12 is a center line X, a sound pressure distribution in a range of 4 m × 4 m in a horizontal plane in contact with the center line X is shown. The electromagnetic transducer 10 exists at the center of the lower side of FIG. 13, and radiated sound is radiated toward the upper side of the drawing. The curve in the figure connects the same sound pressure values, and is a relative value at equal intervals. Also, a line connecting the center of the lower side and the center of the upper side is a front axis A. 13A shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 13B shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. FIG. 13A and FIG. 13B show a state in which the sound pressure immediately before the electromagnetic transducer 10 existing at the center of the lower side is the highest, and the sound spreads outside it to reduce the sound pressure. ing. In FIG. 13A, a sound pressure distribution close to a circle is formed around the electromagnetic transducer 10, but the sound pressure near the front axis A is high. In FIG. 13B, the sound pressure in the vicinity of the front axis A becomes higher, and the sound pressure value decreases faster as the distance from the front axis A increases. Further, sound pressure valleys are formed in directions of ± 45 ° from the front axis A, respectively.

  FIG. 14 is a directional polar pattern diagram showing the directivity of a conventional electromagnetic transducer. The directional polar pattern diagram is a semicircle circle graph with a radius of 2 m, in which the sound pressure on the circle inscribed in the diagram showing the sound pressure distribution in FIG. 13 is plotted. In FIG. 14, a concentric scale indicates a sound pressure value (dB), and a radial scale indicates an angle indicating directivity. 14A is a directional polar pattern diagram when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 14B is a directional polar pattern when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz.

  FIG. 14A shows ± 60 ° when the angle of −6 dB is seen with respect to the sound axis (direction of 0 °), and the half-full angle is 120 °. On the other hand, FIG. 14B shows an angle of −6 dB with respect to the sound axis (in the direction of 0 °), which is ± about 20 ° and a full half angle of 40 °. In addition, a sound pressure valley is formed in the direction of ± 45 ° from the sound axis (0 ° direction), and side lobes are formed on the outside thereof. The half-full angle used for evaluation of the listening range is an angle between directions in which the sound pressure value of the sound axis is reduced by 20 log 0.5 dB (about 6 dB).

  As can be seen from the sound field simulation results shown in FIGS. 13 and 14, the sound emitting holes 20 of the conventional electromagnetic transducer 10 are perforated at equal intervals in the current direction and the arrangement direction, and are emitted from the sound emitting holes. The sound pressure distribution of the radiated sound is almost uniform on the radiation surface of the electromagnetic transducer 10, and the maximum sound pressure level on the front axis of the electromagnetic transducer on the circumference with a constant radius centered on the center of the electromagnetic transducer. And the main lobe exists in the front direction of the electromagnetic transducer 10. When a substantially uniform sound pressure is formed on the radiation surface of the electromagnetic transducer 10, the directivity angle of the main lobe depends on the width dimension of the rectangular electromagnetic transducer 10 in which the radiation sound in the longitudinal direction or the short direction is radiated. To be determined.

  As described above, the conventional electromagnetic converter needs to change the outer dimension of the electromagnetic converter and the outer peripheral dimension of the member on which the sound emitting holes are arranged when the directivity angle needs to be changed or the directivity must be controlled. There was a problem. In addition, the directivity in the direction perpendicular to the current direction or the arrangement direction is symmetrical on both sides of the sound axis, so that there is a problem that the sound radiation direction is the front and the radiation direction or direction angle of the radiated sound cannot be arbitrarily set.

  The present invention has been made in order to solve the above-described problems, and does not change the outer dimension of the electromagnetic transducer or the outer peripheral dimension of the member on which the sound emission holes are arranged, or the radiated sound directivity angle or An object is to obtain an electromagnetic transducer capable of changing the directivity.

The electromagnetic transducer according to the present invention includes a vibration film provided with a permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed, and a coil pattern that is disposed opposite to the formation surface of the multipolar magnetization pattern on the permanent magnet plate. A buffer member disposed between the permanent magnet plate and the diaphragm, a frame that covers and supports the permanent magnet plate, the diaphragm and the buffer member, and the diaphragm on the permanent magnet plate and the frame. And a sound emitting hole for radiating the sound generated to the outside space, wherein a plurality of the sound emitting holes are arranged in a row direction and a column direction of the electromagnetic converter, and the row direction and the column direction Unlike at least every one direction of the sound pressure sequence of said sound release hole is different in the row direction of the pore size of at least one of the direction and the column direction are each sequence, the pore diameter electromagnetic transducer From one end to the other That, or is made smaller.

  According to this invention, since the sound pressure of the radiated sound radiated from the sound emitting holes of the electromagnetic transducer is changed for each arrangement of the sound emitting holes, the outer dimensions or the sound emitting holes of the electromagnetic transducer are arranged. Thus, it is possible to obtain an electromagnetic transducer capable of controlling directivity without changing the outer peripheral dimensions of the members that are used.

Embodiment 1 FIG.
1 is an exploded perspective view showing a configuration of an electromagnetic transducer according to Embodiment 1 of the present invention.
The permanent magnet plates 1 and 2 of the electromagnetic transducer 10 shown in the figure have a strip-shaped multipolar magnetization pattern (alternating N and S poles) made of sintered ferrite magnets on almost the front surface facing the vibrating membrane 3. Parallel striped multi-pole magnetized patterns) appearing on the surface of the permanent magnet plate 1 and a plurality of sound emission at a constant pitch along the neutral zone of magnetization, which is a gap between the multi-pole magnetized patterns. A hole 1a is provided. The vibration film 3 is disposed opposite to the surface of the permanent magnet plate 1 where the multipolar magnetization pattern is formed. When a current flows through the coil pattern 3a formed on the surface, the vibration film 3 is electromagnetically coupled to the permanent magnet plate 1 and has a thickness. Vibrate in the direction. The coil pattern 3a formed on the surface of the vibration film 3 is a coil formed of a meandering conductor pattern having a linear portion longer in the longitudinal direction of the electromagnetic transducer 10, and is printed on a thin and flexible resin film 3b. The straight line portion of the conductor pattern is provided at a position corresponding to the neutral zone of the permanent magnet plate 1.

  The buffer members 4a and 4b are disposed between the permanent magnet plates 1 and 2 and the diaphragm 3, and prevent the generation of noise due to the diaphragm 3 hitting the permanent magnet plates 1 and 2, and function as a suspension. Have The permanent magnet plates 1 and 2, the vibration film 3, and the buffer members 4 a and 4 b are laminated and covered with the upper frame 5 and the lower frame 6. A plurality of sound emitting holes 5 a are provided on the upper surface of the upper frame 5 so as to communicate with the sound emitting holes 1 a of the permanent magnet plate 1 described above.

  Next, the operation of the electromagnetic transducer 10 will be described. Since the vibration film 3 is disposed opposite to the formation surface of the multipolar magnetization pattern in the permanent magnet plate 1, when a current as an audio signal flows through the coil pattern 3a formed on the surface, the coil pattern 3a The multipolar magnetization pattern of the permanent magnet plate 1 is electromagnetically coupled, and audio vibrations are generated in the vibration film 3 in accordance with Fleming's law. Sound waves generated by the audio vibration are emitted to the outside through the sound emission holes 1a and 5a, and audio reproduction is performed.

Next, the arrangement of the sound emission holes provided in the permanent magnet plate 1 and the upper frame 5 of the electromagnetic transducer 10 will be described.
FIG. 2 is a front view of the electromagnetic transducer according to Embodiment 1 of the present invention. The electromagnetic transducer 10 has a longitudinal direction in which a current flows in a direction (hereinafter referred to as a current direction (column direction)) of about 12 cm, a short direction and a direction perpendicular to the current direction (hereinafter referred to as an array direction). (Referred to as row direction)) is formed as a rectangle having a length of about 6 cm (however, in FIG. 2, the lengths in the current direction and the arrangement direction are different for explanation). The center in the current direction is a center line X, and the center in the arrangement direction is a center line Y. Sound emitting holes 20 are formed at equal intervals in the current direction and the arrangement direction, and 20 holes are provided per row in the current direction and 10 per row in the arrangement direction. The sound emission holes 20 have an oblique eye arrangement pattern that is an arrangement pattern in which the rows are alternately shifted in both the current direction and the arrangement direction, and the sound emission holes 20 are arranged at the intersections of oblique oblique lines.

The hole diameter of the sound emitting holes 20 is changed for each row in the current direction, and is configured to be the smallest hole diameter at the left end portion of the electromagnetic transducer 10 and gradually increase toward the right end portion.
As the hole diameter of each row in the current direction, as shown in FIG. 3 (a), the hole diameter is expanded by an equal ratio of 1.1 times (or 1.2 times, 1.3 times ...) with respect to the minimum hole diameter M. As shown in FIG. 3 (b), it is conceivable that the minimum pore diameter M is gradually increased by 1.1 times, 1.2 times, 1.3 times, and so on. The hole diameter for each column in the arrangement direction is not changed.

The result of the sound field simulation in the electromagnetic transducer 10 having the configuration of FIG. 2 will be described. In the description, in order to approximate a point sound source, description will be made using a sound field simulation result of a model in which each sound emitting hole is arranged on a flat baffle surface.
FIG. 4 is a diagram showing the sound pressure distribution of the electromagnetic transducer according to the first embodiment of the present invention, and shows the sound pressure distribution in the range of 4 m × 4 m in the horizontal plane in contact with the center line X of the electromagnetic transducer 10. . The electromagnetic transducer 10 exists in the center of the lower side of FIG. 11, and radiated sound is radiated toward the upper side of the drawing. The curve in the figure connects the same sound pressure values, and is a relative value at equal intervals. Further, a line connecting the center of the lower side and the center of the upper side is defined as a front axis A (hereinafter, the same applies to the drawings showing the sound pressure distribution).

  4A shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 4B shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. FIG. 4A constitutes a concentric distribution close to a circle centering on the electromagnetic transducer 10 existing at the center of the lower side, but is closer to the circle than FIG. 13A shown in the conventional example. The sound pressure distribution is shown, and the change of the sound pressure distribution due to the change of the hole diameter of the sound emitting hole 20 can be seen. Compared with FIG. 13 (b) shown in the conventional example, FIG. 4 (b) does not show the valley of the sound pressure existing in the direction of about ± 45 ° from the front axis A, and there is a clear side lobe. do not do. The sound pressure distribution pattern is also asymmetric with respect to the front axis A, and it can be seen that the radiation direction of the radiated sound changes.

  FIG. 5 is a directional polar pattern diagram showing the directivity of the electromagnetic transducer according to Embodiment 1 of the present invention. The directional polar pattern diagram is a semicircle circle graph having a radius of 2 m, in which the sound pressure on the circle inscribed in the diagram showing the sound pressure distribution in FIG. 4 is plotted. In FIG. 5, concentric scales indicate sound pressure values (dB), and radial scales indicate angles indicating directivity (hereinafter, the same applies to the diagrams showing the directional polar pattern). 5A is a directional polar pattern diagram when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 5B is a directional polar pattern when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz.

  In FIG. 5A, when an angle of −6 dB with reference to the sound axis (direction of 0 °) is seen, it is ± about 90 °, and the half-full angle is about 180 °. Compared with FIG. 14 (a) shown in the conventional example, FIG. 5 (a) is slower in decreasing the sound pressure value when moving away from the sound axis (0 ° direction), and has wide directivity. I understand that. In FIG.5 (b), when the angle which becomes -6 dB on the basis of a sound axis (0 degree direction) is seen, it will be about +/- 25 degree, and a half angle is about 50 degrees. Also, the directivity pattern is asymmetric with respect to the sound axis (0 ° direction). Compared with FIG. 14B shown in the conventional example, it can be seen that the pattern has a wider directivity, a clear side lobe is not formed, and the directivity pattern changes. The sound axis is an axis connecting the center of the electromagnetic transducer 10 and the point where the sound pressure is maximized. Moreover, the half-full angle used for the evaluation of the listening range is an angle between directions in which the sound pressure value of the sound axis is reduced by 20 log 0.5 dB (about 6 dB) (hereinafter the same).

  As described above, according to the first embodiment, since the hole diameter of the sound emitting hole is changed and the hole diameter is changed for each column in the current direction of the electromagnetic converter, the outer dimension of the electromagnetic converter is changed. Therefore, it is possible to control the directivity angle and directivity without realizing desired acoustic characteristics.

  In the above-described first embodiment, the example in which the hole diameter is changed for each row in the current direction of the electromagnetic transducer has been shown for the hole diameter of the sound emitting hole, but the hole diameter is changed for each row in the arrangement direction. May be. Moreover, you may comprise so that a hole diameter may be changed simultaneously for every row | line | column of an electric current direction and an arrangement | sequence direction.

Embodiment 2. FIG.
FIG. 6A is a cross-sectional view of an electromagnetic transducer according to Embodiment 2 of the present invention, and FIG. 6B is a front view thereof. The difference from the electromagnetic transducer according to Embodiment 1 shown in FIG. 2 is that the diameter of the sound emitting holes 20 is uniform in both the current direction and the arrangement direction, as in FIG. The phase of the radiated sound radiated from is changed for each arrangement in the current direction. Hereinafter, the same or corresponding parts as those of the electromagnetic transducer according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified.

  The radiated sound generated by the electromagnetic transducer 10 is radiated from the sound emitting hole 20 through the sound path 30. It is assumed that the sound emitting holes 20 are arranged at a uniform pitch in both the current direction and the arrangement direction, and sound having the same intensity is emitted. The length of the sound path 30 is changed for each arrangement in the current direction, and the left end portion of the electromagnetic transducer 10 is the longest and is gradually shortened toward the right end portion. With this configuration, the phase of the radiated sound gradually proceeds in accordance with the length of the sound path 30, and in the second embodiment, + 5 ° for each column as it goes to the right end column with respect to the leftmost end column in the current direction. An advanced phase difference is applied. The phase difference can be arbitrarily set such as + 5 ° or + 10 ° with respect to the adjacent array.

Next, the result of the sound field simulation in the electromagnetic transducer 10 having the configuration of FIG. 6 will be described.
FIG. 7 is a diagram showing the sound pressure distribution of the electromagnetic transducer according to Embodiment 2 of the present invention. FIG. 7A shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 7B shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. In both FIG. 7A and FIG. 7B, the radiation direction of the radiated sound is inclined to the right side with respect to the front axis A, and the sound pressure distribution is also asymmetric with respect to the front axis A.

  FIG. 8 is a directional polar pattern diagram showing the directivity of the electromagnetic transducer according to Embodiment 2 of the present invention. 8A is a directional polar pattern diagram when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 8B is a directional polar pattern when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. In FIG. 8A, the sound axis of the radiated sound has moved in the direction of + about 20 °, and there is no half-width angle. Further, in FIG. 8B, the sound axis of the radiated sound has moved in the direction of about + 10 °, and when an angle of −6 dB is seen with respect to the sound axis (the direction of about 10 °), +40 ° and -about 15 °, with a half-full angle of about 55 °. From these facts, FIGS. 8A and 8B have a wider directivity than that of FIGS. 14A and 14B shown in the conventional example, and further, in the radiation direction of the radiated sound. Change is seen.

  As described above, according to the second embodiment, the length of the sound path connected to the sound emission holes is changed for each arrangement in the current direction so that the phase is advanced. The directivity angle and directivity can be controlled without changing the outer dimension, and desired acoustic characteristics can be realized.

  In the second embodiment, the example in which the length of the sound path is changed for each arrangement in the current direction of the electromagnetic transducer has been described. However, the sound path length may be changed for each arrangement in the arrangement direction. Furthermore, as an example of a method for advancing the phase, the example of changing the length of the sound path has been shown, but without changing the length of the sound path, a transfer circuit and a power amplifier are provided to drive a vibration film-like individual pattern, It is good also as a structure which changes a phase electrically.

Embodiment 3 FIG.
In Embodiments 1 and 2, the sound pressure of the radiated sound is changed by changing the hole diameter of the sound emission holes for each array, or the phase of the radiated sound is changed by changing the length of the sound path for each array. In this embodiment, the state of the radiated sound emitted from the sound emitting holes is changed, but in the third embodiment, the state of the radiated sound emitted from each sound emitting hole is the same, and the arrangement interval of the sound emitting holes is set. Change. Hereinafter, the same or corresponding parts as those of the electromagnetic transducer according to the first embodiment are denoted by the same reference numerals as those used in the first embodiment, and the description thereof is omitted or simplified.

  FIG. 9 is a front view of an electromagnetic transducer according to Embodiment 3 of the present invention. The arrangement interval of the sound emitting holes 20 in the current direction is configured to be the narrowest pitch at the left end of the electromagnetic transducer 10 and gradually increase toward the right end. As the arrangement interval in the current direction, 1.1 times the minimum interval L (or 1.2 times, 1.3 times...) For example, it can be increased by 1.2 times, 1.3 times, and so on. All arrangement intervals in the arrangement direction are configured to have a uniform pitch. In addition, it is assumed that a sound having the same intensity is emitted from the sound emission hole 20.

Next, the result of the sound field simulation in the electromagnetic transducer 10 having the configuration of FIG. 9 will be described.
FIG. 10 is a diagram showing the sound pressure distribution of the electromagnetic transducer according to Embodiment 2 of the present invention. 10A shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 10B shows the sound pressure distribution when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. 10 (a) and 10 (b), the sound pressure distribution is gathered near the front axis A, and has a narrower sound pressure distribution than the conventional example shown in FIGS. 13 (a) and 13 (b). I understand that Further, the radiation direction of the radiated sound is slightly inclined to the left side with respect to the front axis A.

  FIG. 11 is a directional polar pattern diagram showing directivity characteristics of the electromagnetic transducer according to Embodiment 4 of the present invention. FIG. 11A is a directional polar pattern diagram when the frequency (sound pressure) of the electromagnetic transducer is 4 kHz, and FIG. 11B is a directional polar pattern when the frequency (sound pressure) of the electromagnetic transducer is 8 kHz. In FIG. 11A, when an angle of −6 dB with respect to the sound axis (direction of about 0 °) is seen, it is ± about 20 °, and the half-full angle is about 40 °. FIG. It turns out that it has sharper directivity than (a). Further, in FIG. 11B, when an angle of −6 dB with reference to the sound axis (direction of about 0 °) is seen, it is ± about 7-8 °, and the half-full angle is about 15 °. It turns out that it has sharper directivity than shown FIG.14 (b) shown. 11A and 11B that the sound axis is inclined to the left by several degrees. In the calculation of the half-full angle, the sound axis is set to a direction of about 0 ° for convenience.

  As described above, according to the third embodiment, the arrangement of the sound emitting holes is changed, and the arrangement interval in the current direction of the electromagnetic transducer becomes the narrowest pitch at the left end portion of the electromagnetic transducer, and gradually increases toward the right end portion. Since the pitch is so wide that the directivity angle and directivity can be controlled without changing the outer dimensions of the electromagnetic transducer, desired acoustic characteristics can be realized.

  In the above-described third embodiment, an example in which the arrangement interval in the current direction of the electromagnetic transducer is changed with respect to the arrangement of the sound emitting holes has been described, but the arrangement interval in the arrangement direction may be changed. . Moreover, you may comprise so that the arrangement | sequence space | interval of an electric current direction and an arrangement | sequence direction may be changed simultaneously.

  Furthermore, in Embodiment 1-3 mentioned above, although the structure which arrange | positions a sound emission hole by the oblique eye arrangement pattern was shown, it is not limited to this. In the above-described first to third embodiments, an example in which the sound emitting holes are perforated according to the coil pattern on the vibration film or the magnetization pattern of the permanent magnet plate is shown. Even if it is done, the same effect can be obtained.

It is a disassembled perspective view which shows the structure of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is a front view of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is a figure which shows the example of an arrangement space | interval of the sound emission hole of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is a figure which shows the sound pressure distribution of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is a directivity polar pattern figure which shows the directivity characteristic of the electromagnetic transducer which concerns on Embodiment 1 of this invention. It is a front view of the electromagnetic transducer which concerns on Embodiment 2 of this invention. It is a figure which shows the sound pressure distribution of the electromagnetic transducer which concerns on Embodiment 2 of this invention. It is a directivity polar pattern figure which shows the directivity characteristic of the electromagnetic transducer which concerns on Embodiment 2 of this invention. It is a front view of the electromagnetic transducer which concerns on Embodiment 3 of this invention. It is a figure which shows the sound pressure distribution of the electromagnetic transducer which concerns on Embodiment 3 of this invention. It is a directivity polar pattern figure which shows the directivity characteristic of the electromagnetic transducer which concerns on Embodiment 3 of this invention. It is a front view of the conventional electromagnetic transducer. It is a figure which shows the sound pressure distribution of the conventional electromagnetic transducer. It is a directional polar pattern figure which shows the directional characteristic of the conventional electromagnetic transducer.

Explanation of symbols

  1, 2 Permanent magnet plate, 1a, 5a, 20 Sound emission hole, 3 Vibration film, 3a Coil pattern, 3b Resin film, 4a, 4b Buffer member, 5 Upper frame, 6 Lower frame, 10 Electromagnetic transducer, 30 sound Road, A Front axis, X, Y Center line.

Claims (3)

A permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed;
A vibrating membrane provided with a coil pattern disposed opposite to the formation surface of the multipolar magnetization pattern in the permanent magnet plate;
A buffer member disposed between the permanent magnet plate and the diaphragm;
A frame that covers and supports the permanent magnet plate, the diaphragm and the buffer member;
In the electromagnetic transducer comprising the permanent magnet plate and the frame, sound emitting holes for radiating the sound generated by the vibration film to the external space,
A plurality of the sound emission holes are arranged in the row direction and the column direction of the electromagnetic transducer, and the sound pressure in at least one of the row direction and the column direction is different for each arrangement ,
The sound emitting hole has a hole diameter in at least one of the row direction and the column direction that differs for each arrangement, and the hole diameter increases or decreases from one end to the other end of the electromagnetic transducer. An electromagnetic transducer. A permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed;
A vibrating membrane provided with a coil pattern disposed opposite to the formation surface of the multipolar magnetization pattern in the permanent magnet plate;
A buffer member disposed between the permanent magnet plate and the diaphragm;
A frame that covers and supports the permanent magnet plate, the diaphragm and the buffer member;
In the electromagnetic transducer comprising the permanent magnet plate and the frame, sound emitting holes for radiating the sound generated by the vibration film to the external space,
A plurality of the sound emission holes are arranged in the row direction and the column direction of the electromagnetic transducer, and the sound pressure in at least one of the row direction and the column direction is different for each arrangement,
The sound emission hole is different for each of the row direction and at least one direction of the sound圧位phase of the column is arranged, the sound圧位phase proceeds from one end to the other end of the electromagnetic transducer, or delayed conductive magnetic transducer you wherein a. A permanent magnet plate on which a strip-shaped multipolar magnetization pattern is formed;
A vibrating membrane provided with a coil pattern disposed opposite to the formation surface of the multipolar magnetization pattern in the permanent magnet plate;
A buffer member disposed between the permanent magnet plate and the diaphragm;
A frame that covers and supports the permanent magnet plate, the diaphragm and the buffer member;
In the electromagnetic transducer comprising the permanent magnet plate and the frame, sound emitting holes for radiating the sound generated by the vibration film to the external space,
A plurality of the sound emission holes are arranged in the row direction and the column direction of the electromagnetic transducer, and the sound pressure in at least one of the row direction and the column direction is different for each arrangement,
The sound output holes, the row direction and at least the arrangement interval of one direction of the column direction is different for each sequence, the arrangement interval increases from one end to the other end of the electromagnetic transducer, or smaller conductive magnetic transducer you wherein a.

Images