Ceramic plate vibration speaker

Abstract

By using a ceramic plate as a diaphragm, this invention provides a ceramic plate vibration speaker that can reproduce sounds in a frequency range close to acoustically ideal, particularly a wide frequency range from the audible frequency range to the high frequency range, through plane wave vibration. [Solution] This vibration speaker uses a ceramic plate as its diaphragm, and a new metal ring is inserted between it and the actuator that drives it to fix it in place. This is the first ceramic plate vibration speaker that can reproduce plane waves up to ultra-high frequencies, including the Hi-Res range.

Description

Technical Field

[0001] The present invention relates to a ceramic plate vibration speaker using a ceramic plate as a diaphragm, and particularly to a ceramic plate vibration speaker for planar wave high-frequency range vibration that can reproduce sounds in a wide frequency range from an audible frequency band to a high-frequency band by planar wave vibration.

Background Art

[0002] Conventionally, a speaker has been disclosed in which a piezoelectric body and a magnet are opposed and arranged on a diaphragm, and a coil is arranged opposite to this magnet (see Patent Document 1: JP-A-2011-166565). It is said that the shape can be made thin and the sound pressure characteristics in the low frequency range can be improved to obtain high-quality sound.

[0003] Conventionally, in addition, a piezoelectric speaker having a bimorph type or unimorph type piezoelectric vibrator supported to be vibratable inside a frame has been disclosed (see Patent Document 2: Japanese Utility Model Laid-Open No. 01-143599). The metal electrode plate of this piezoelectric vibrator is made of a magnetic metal, and a magnet that applies an attractive force to a position offset from the center of the piezoelectric vibrator is arranged in the vicinity of the piezoelectric vibrator. In this piezoelectric speaker, regular higher-order divided vibrations are suppressed by the attractive force of the magnet acting on the offset position of the metal electrode plate of the piezoelectric vibrator, and the frequency characteristics are improved.

[0004] On the other hand, a general-purpose speaker has been disclosed in which a porous sintered body is used for a baffle plate or a porous sintered body is applied to a mount member (see Patent Document 3: JP-A-2003-023685). The porous sintered body is generally formed into a flat plate shape by electric heating and pressing using metal chips with a particle size of 6 to 50 mesh. During this forming process, the surfaces of the metal chips melt and fuse with each other, and heat escapes from the inside of the sintered body and cools, so that the pores on the outer surface are sparse and the pores inside are dense.

Prior Art Documents

Patent Documents

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-166565 [Patent Document 2] Japanese Utility Model Publication No. 01-143599 [Patent Document 3] Japanese Patent Publication No. 2003-023685 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, conventional speakers and moving-coil speakers can only reproduce so-called spherical waves, and if the position and angle from the sound source are different, the sound pressure and sound characteristics will sound different to the listener.

[0007] In contrast to such spherical wave speakers, there are also so-called planar vibration speakers, which use a flat diaphragm to vibrate the actuator to reproduce sound. In planar vibration speakers, since vibration waves can be transmitted as planar waves from the entire surface of the diaphragm, the influence of the actuator's position and angle on how the sound is perceived by the listener is reduced.

[0008] Unlike conventional moving coil speakers, planar vibration speakers do not produce sound by directly vibrating the air with the actuator's own diaphragm. In other words, the actuator of a vibration speaker does not have the function of vibrating the air significantly on its own, and it is necessary to transmit the sound vibrations from the actuator to some kind of plate (diaphragm). Therefore, if there is a loss in the transmission of sound vibrations from the actuator to the diaphragm, problems with the acoustic reproduction range will occur, such as the absence of certain frequency bands. In particular, sound components in the high frequency band are easily dispersed when the sound signal from the actuator's voice coil is transmitted, and depending on the transmission structure and diaphragm, it has been difficult to reproduce a wide frequency range of sound or reproduce sound with a good sense of presence.

[0009] Therefore, the object of the present invention is to provide a ceramic plate vibration speaker that uses a ceramic plate as a diaphragm to reproduce sound in a frequency range close to acoustically ideal, particularly a wide frequency range from the audible frequency range to the high frequency range, by plane wave vibration. [Means for solving the problem]

[0010] To address the above issues, the following measures have been taken. Note that the numbers, letters, or combinations thereof following each term are symbols added for convenience to facilitate understanding by referring to the examples, and do not inherently limit the composition or concept.

[0011] (1) The ceramic plate vibrating speaker of the present invention is An actuator (1) comprising a facing part having a central hole and facing the vibration transmission direction, a voice coil positioned near the central hole of the facing part, an annular magnet hollow-supported near the periphery of the voice coil, and a frame that frames these, A ceramic diaphragm (2) made by sintering natural ceramic raw materials and forming it into a plate shape to a predetermined thickness, A ceramic plate vibration speaker is formed by joining components via a transmission ring (106) made of a metal ring, The diaphragm is characterized in that the annular end face of the transmission ring is bonded to the plate-shaped back surface of the diaphragm, and vibrations in the frequency range including the audible frequency range and the ultra-high frequency range from 20 kHz to 60 kHz (so-called Hi-Res: the ultra-high frequency band that affects high resolution) reproduced by the actuator are transmitted only through this transmission ring as a vibration transmitting material, causing the diaphragm to vibrate as a plane wave from the audible range to the high frequency range.

[0012] (2) <Transmission ring> In the ceramic plate vibrating speaker, The transmission ring (106) consists of a metal cylinder having only a uniform annular cross-section. The annular end face of the base end of the cylindrical body of the transmission ring (106) makes surface contact with the coil end of the voice coil, The transmission ring (106) is characterized in that the annular end face at the tip of the cylindrical body is fixed to the diaphragm with an annular end face shape having a substantially uniform annular width in the circumferential direction, without having any outward protrusions.

[0013] (3) <Made of brass> In any of the above ceramic plate vibrating speakers, The transmission ring (106) is made of a single piece of brass metal, and its annular end face is fixed to the diaphragm by zinc welding in an annular shape.

[0014] (4)<Plate thickness 2D> In any of the above ceramic plate vibrating speakers, The plate thickness (2D) of the diaphragm (2) is set to a standard thickness within the range of 2.5 to 22.0 mm, and the thickness variation range is set to ±1.0 mm or less relative to the standard thickness. This plate is characterized by having a surface layer on the outermost surface within its thickness 2D, on which a design or embossed pattern is displayed.

[0015] Within the above range, it is possible to ensure sufficient strength to prevent easy damage and sound transmission capabilities to adequately transmit plane wave vibrations from the audible frequency range to the ultra-high frequency range.

[0016] (5) <Porosity 2P> In any of the above ceramic plate vibrating speakers, The diaphragm (2) is made of a ceramic plate made of naturally fired wood. The diaphragm (2) is characterized in that its plate thickness (2D) is set to a standard thickness within the range of more than 4.0 mm and less than 20.1 mm, and its porosity (2P) is set to a range of 5.0 percent or more (preferably more than 12.0%) and less than 55.0%.

[0017] In the diaphragm with a reference thickness within the range where the plate thickness (2D) is more than 4.0 mm and less than 20.1 mm, if the porosity is within the above range, sufficient sound pressure can be maintained from the audible frequency band to the ultra-high frequency band, and the strength of the diaphragm can be ensured. According to the experiments of the inventor, at least in the diaphragm with the reference thickness within the above range, when the porosity is in the range exceeding 0.09% and less than 5.0%, which is below the above range, the sound pressure in the ultra-high frequency band will be insufficient, and it has been confirmed that when the porosity exceeds 55.0%, the strength will be insufficient. For example, some of the test bodies described later correspond to this.

[0018] Particularly, when the diaphragm is composed of an art display with an artistic pattern or painting on its surface, the set range of the porosity also affects the texture of the surface, and when a glaze layer is provided, it also affects the fixing degree of the glaze. Note that the adjustment of the porosity can be controlled, for example, by reducing the firing temperature and the densification (controlling the maximum temperature of the stepwise temperature increase).

[0019] (6) Glaze layer In any of the above ceramic plate vibration speakers, the diaphragm (2) has a glaze layer with a predetermined thickness within the range of more than 0.1 mm and less than 2.0 mm on its surface within the range of the plate thickness (2D).

Effect of the invention

[0020] By taking the above various measures, the present invention can provide a ceramic plate vibration speaker that can reproduce sounds in a wide frequency range, particularly from the audible band to the high-resolution band, as plane waves, through uniform and efficient sound transmission to a flat ceramic plate via a metal transmission ring, resulting in an acoustically ideal frequency band.

Brief description of the drawings

[0021] [Figure 1] Rear perspective view of the ceramic plate vibration speaker of Embodiment 1 and enlarged view of its α-α part. [Figure 2] Rear view of the ceramic plate vibration speaker of Embodiment 1. [Figure 3]A centrally enlarged cross-sectional view showing the internal configuration of the ceramic plate vibration speaker of Embodiment 1. [Figure 4] Enlarged view of the β-β region in Figure 3. [Figure 5] A rear view of a ceramic plate vibrating speaker according to Embodiment 2 of the present invention. [Figure 6] Side view of the main part of the ceramic plate vibration speaker of Embodiment 2. [Figure 7] A centrally enlarged cross-sectional view showing the internal structure of the γγ region in Figure 6. [Figure 8] A centrally enlarged cross-sectional view showing the internal configuration of the ceramic plate vibration speaker of Embodiment 3. [Figure 9] A schematic diagram of the sound pressure test conditions in the comparative test. [Figure 10a] Frequency measurement graph of the ceramic plate vibration speaker of test specimen 10a [Figure 10b] Frequency measurement graph of the ceramic plate vibration speaker (without metal ring) of comparison unit 10b. [Figure 11a] Frequency measurement graph of diaphragm comparison unit 11a (made of aluminum) [Figure 11b] Frequency measurement graph of diaphragm test specimen 11b (ceramic plate with picture) [Figure 11c] Frequency measurement graph of diaphragm test specimen 11c (ceramic plate without picture, with peel-off section) [Figure 11d] Frequency measurement graph of diaphragm test specimen 11d (ceramic plate without design) [Figure 12] Sound pressure comparison graph of plane wave speaker and spherical wave speaker [Figure 13] Sound pressure measurement graphs for each test specimen A-F [Figure 14] Table showing the properties of the diaphragm of each test specimen. [Best Mode for Carrying Out the Invention]

[0022] Hereinafter, examples of embodiments for carrying out the present invention will be described with reference to the figures shown as examples. However, this is not intended to limit the present invention to these embodiments. Figures 1 to 4 show the ceramic plate vibration speaker of Embodiment 1 and its internal configuration, Figures 5 to 7 show the ceramic plate vibration speaker of Embodiment 2 and its internal configuration, and Figure 8 shows the internal configuration of the ceramic plate vibration speaker of Embodiment 3.

[0023] Embodiment 1 involves joining a circular, thin actuator 1 to the back surface of a rectangular diaphragm 2 via a transmission ring 106. Figures 1 and 2 show the joining state of the actuator 1 on the back surface 2B of the diaphragm 2. The actuator 1 is joined with a joining center that is offset by a displacement dimension 21GL in the height direction and a displacement dimension 22GL in the width direction from the centroid 2GX, which is the intersection of the diagonals of the diaphragm 2. Preferably, these displacement dimensions 21GL and 22GL are set within a range of approximately 5-20% or less of the total height 21SL and total width 22SL of the corresponding diaphragm 2.

[0024] Figure 3 is a cross-sectional view of the central α-α section of Figure 1, and Figure 4 is a further enlarged view of the ββ section of Figure 3. As shown in Figures 3 and 4, the actuator 1 of Embodiment 1 is joined to the diaphragm 2B only via the transmission ring 106.

[0025] Actuator 1 has a movable magnet type magnetic circuit formed on the upper part of a circular fixed plate 104 that is positioned parallel to the diaphragm, and sound vibrations are transmitted from the central hole of the fixed plate 104 toward the diaphragm, with the central hole of the fixed plate 104 serving as the vibration space.

[0026] Then, the coil end of the voice coil 103, which is exposed along the edge of the central hole of the fixing plate 104 of the actuator 1, is surface-bonded to the base end surface 106A1 of the annular transmission ring 106, which is made of a short cylinder with a thickness of 106W, and the front end surface 106A2 of the transmission ring 106 is surface-bonded to the diaphragm 2 (Figures 3 and 4).

[0027] More specifically, as shown in Figures 3 and 4, the actuator 1 has a circular fixing plate 104 with a central hole, which is positioned parallel to the back surface 2B of the diaphragm in close proximity. A cylindrical frame 105 is fixed to the upper surface around the fixing plate 104, and a cylindrical top plate 110, which holds a ring-shaped (donut-shaped) magnet 109 on its upper surface, is bonded to a perforated circular plate at the top of the frame 105. The top plate 110 is made of a circular plate with a central hole, and the magnet 109 is fixed to its upper surface. Furthermore, a bottom plate 108B with a cylindrical inner yoke protruding from the center is fixed to the upper part of the top plate 110. As a result, a magnetic circuit is formed inside the ring-shaped magnet 109, and vibrations are transmitted to the voice coil (bobbin) 103 arranged around the inner yoke 101BT protruding from the center of the magnetic circuit 102.

[0028] The voice coil 103 consists of a circular wire coil, and the coil end closest to the diaphragm is fitted into and fixed in an annular slit in the tapered portion of the edge of the central hole of the fixing plate 104. The cylindrical top plate 110 and the ring-shaped magnet constitute a cylindrical outer yoke. The space in the center of the outer yoke and the columnar inner yoke 108T connected to it via a bottom plate form a magnetic circuit 102 within the donut-shaped hole of the magnet 109, and a vibration space 101 enclosed in a cylindrical shape by the voice coil 103 and the transmission ring 106 is formed in the space in the direction of the diaphragm connected to the magnetic circuit 102. As shown in Figure 3, the vibration space 101 within the voice coil and the drive space 102 above the base of the voice coil are secured.

[0029] Furthermore, as shown in Figure 4, the wire diameter 103W of the voice coil's coil wire is approximately one-eighth of the ring width 106W of the transmission ring 106, and the circular wire 103S of the voice coil's coil end is fixed to the center of the ring width 106W (Figure 4). In addition, the central hole 104 has a tapered portion 104T at the upper part of its edge.

[0030] The diaphragm thickness 2D is the sum of the thickness 2FD of the glaze layer 2F and the thickness 20D of the remaining basic components 20.

[0031] Embodiment 2, shown in Figures 5-7, has a ring width 106W of the annular contact surface that is approximately six times the coil width of the voice coil. However, the radial displacement of the ring width is set symmetrically inward and outward from the center of the coil width. Furthermore, the extended end of the actuator's fixing plate 111 is fixed with a remote holding pin 112 around a remote holding distance 113R. However, since it makes indirect contact via a cushioning material 113, it does not function as a transmission body. Reference numeral 112 denotes a remote holding pin, reference numeral 113 denotes a cushioning material, and reference numeral 113R denotes the remote holding distance to the cushioning material.

[0032] Embodiment 3, shown in Figure 8, consists of an art object with an uneven surface 2F having a recessed shape. The diaphragm's average thickness 2AH is directionally variable, and it has a maximum height of approximately 150% of that, 246H, near the annular contact surface of the transmission ring 106.

[0033] In any embodiment, the vibration speaker of the present invention has a structure in which a metal ring 106 of the present invention acts as the sole vibration transmitter between a conventional actuator comprising a magnetic circuit 102, a voice coil 103, a fixing plate 104, and a frame 105, and a ceramic diaphragm 107.

[0034] (Actuator) The actuator of this embodiment comprises a magnetic circuit 102, a voice coil 103, a fixing plate 104, and a frame 105. Although this configuration is an external magnet type using a ferrite magnet, an internal magnet type or a hybrid type with a piezoelectric element may also be used, and the type is not limited. It is preferable that the actuator 1 is mounted at a position offset in the vertical and horizontal directions from the centroid (intersection of the diagonals) 2GX, as shown in Figures 1 and 2, or at a position offset by 21PL and 22PL from the corners, as shown in Figure 5.

[0035] (diaphragm 2) As the diaphragm 2, a rectangular ceramic plate of any size, made from a ceramic body of naturally fired material, is used.

[0036] It is preferable to control the raw material distribution of the ceramic plate and firing conditions (temperature changes and time in the multi-stage firing process) or to control and adjust the cooling conditions after firing so that the structural part of the diaphragm 2 contains an appropriate amount of air bubbles and achieves a predetermined porosity 2P (apparent porosity).

[0037] By hardening the surface of the diaphragm with a thin layer of glaze, a honeycomb-type diaphragm with ideal internal strength can be created. The plate thickness can be used from 1 to 20 mm, depending on the overall size. Within the aforementioned plate thickness range, one or more layers of glaze may be applied to the surface, or both sides may be glazed. However, the actuator mounting area must be flat enough to allow for adhesion.

[0038] (Thickness of the diaphragm (2) (2D) The plate thickness (2D) of the diaphragm (2) is set to a standard thickness within the range of more than 2.5 mm and less than 22.0 mm, and with a thickness variation range of ±1.0 mm or less relative to the standard thickness. It is preferable that the outermost surface within the plate thickness 2D has a surface layer on which a design or embossed pattern is displayed. Furthermore, it is preferable to set the standard thickness to a range of more than 2.5 mm and less than 4.0 mm.

[0039] (Relationship between plate thickness and porosity) According to comparative tests by the inventors, it is preferable that the plate thickness (2D) of the diaphragm (2) be set to a standard thickness within the range of more than 4.0 mm and less than 20.1 mm, and that the porosity (2P) of the entire diaphragm (2) be set to a range of 5.0% or more and less than 55.0%.

[0040] (Thickness of the glaze layer) Preferably, the diaphragm (2) has a glaze layer on its surface with a predetermined thickness in the range of more than 1.0 mm to less than 2.0 mm, within the range of the plate thickness (2D).

[0041] (Comparison of the diaphragm of the present invention with a conventional resin plate) When using a flat diaphragm, a honeycomb-structured resin plate is used for strength reasons. However, in the target ultra-high frequency range (10kHz to 40kHz), the vibration signal from the actuator is attenuated within the plate, causing the reproduced sound to be attenuated at ultra-high frequencies. In contrast, the present invention uses a ceramic plate for the diaphragm, thereby maintaining sufficient sound pressure from the audible frequency range to the ultra-high frequency range. Furthermore, by setting the plate thickness (2D) of the diaphragm (2) to a standard thickness within a predetermined range, and with a thickness variation of ±1.0 mm or less relative to the standard thickness, internal strength can be maintained.

[0042] Furthermore, because the ceramic diaphragm of the present invention has relatively high hardness, the vibrations of the actuary are transmitted across the entire surface, which is effective for plane wave reproduction.

[0043] Next, regarding the method for driving the ceramic diaphragm of the present invention, since ceramic plates have strength, striking one spot strongly is more efficient in producing ultra-high frequencies than striking a wider area, so the actuator and the ceramic plate are coupled in the structure shown in Figure 1.

[0044] (Metal transmission ring) In order to efficiently transmit the high-frequency vibrations contained in the longitudinal vibration of the voice coil to the diaphragm, it is necessary to fix the tip of the bobbin on which the voice coil 103 is wound to the back surface of the diaphragm. However, the bobbin is weak, with a thickness of only about 0.1 to 0.2 mm, and it is difficult to directly fix it to the back surface of the diaphragm, which is large and not necessarily a smooth mounting surface.

[0045] Therefore, a cylindrical metal transmission ring of the appropriate size is pre-attached to the tip of the voice coil. The annular end of the base of the transmission ring is bonded perpendicularly to the tip surface of the voice coil, and the annular end of the tip is bonded perpendicularly to the back surface of the diaphragm, so that all vibrations from the tip of the voice coil bobbin can be transmitted to this metal ring.

[0046] Sound resonates within the vibrating space inside the metal ring, allowing for the transmission of sound vibrations with uniform spread in the circumferential direction of the annular end face, as well as efficient transmission of hammer-shaped sound vibrations along the height direction of the cylinder. As shown in Figure 10, this effect significantly improves the characteristics of the bandwidth (10kHz to 40kHz) necessary for high-resolution audio playback.

[0047] The metal ring should preferably be made of brass, but other metals are also acceptable. The width of the metal ring (106W) should ideally be within the range of 1.0 mm to 5.0 mm, and the thickness should ideally be within the range of 1.0 mm to 10.0 mm. However, the end face must be annular, i.e., ring-shaped.

[0048] Furthermore, to prevent dust from entering the voice coil 103 during assembly, a thin aluminum disc about 0.5 mm thick may be placed on the side of the metal ring 106 that contacts the diaphragm 107.

[0049] (Effects of the embodiment) According to the present invention, the front surface of the ceramic plate becomes a planar wave speaker capable of reproducing up to the high-resolution frequency range, unlike conventional vibration speakers for art. Therefore, in addition to the characteristic sound of planar waves, high-resolution playback is possible, allowing for the creation of a more sophisticated playback space, including relaxation sound reproduction.

[0050] Furthermore, this invention uses a ceramic plate with compatible physical properties as its diaphragm, thereby bringing out the characteristics of the ceramic plate in terms of sound quality. By driving it with the actuator of this invention, a vibration speaker capable of reproducing high-resolution audio frequencies is constructed. Moreover, while ordinary speakers reproduce spherical waves, the vibration speaker enables planar wave reproduction that is close to acoustically ideal.

[0051] (Comparison with conventional actuators) In conventional actuators, the fixed plate and the voice coil are fixed together with adhesive, and the entire surface of the fixed plate is surface-bonded to the diaphragm. In this configuration, the vibration of the voice coil driven by the input electrical signal drives the fixed plate, and the diaphragm, which is surface-bonded to the fixed plate, drives itself together with the bonded fixed plate, thereby emitting sound from the diaphragm.

[0052] However, in this configuration, sound is transmitted by surface contact using a plate-shaped fixed plate as a vibration transmitter. As a result, the ultra-high frequency vibration components (10kHz to 40kHz) included in the voice coil vibration are dispersed, and the diaphragm cannot be sufficiently driven by the ultra-high frequency vibration.

[0053] In contrast, the present invention uses only a transmission ring 106 made of a metal annular body as the effective transmission element, making annular contact with the diaphragm and securing a cylindrical vibration space inside the actuator. As a result, even a vibration speaker can reproduce sound with a wider bandwidth than a conventional speaker.

[0054] Figures 10 and onward show the frequency characteristics of test specimen X of an embodiment of the present invention and a voice coil type vibration speaker, which is a comparative test specimen of a conventional example, as measured by the experimental configuration shown in Figure 9.

[0055] The experimental setup shown in Figure 9 involves measuring the frequency characteristics of a microphone MC while a diaphragm 2, driven by an actuator 1 via an amplifier AP, is supported vertically by a processing terminal equipped with a signal generation application AP1 and a waveform analysis application AP2. The diaphragm 2 is clamped on a table using a vertical vice holder HP via a rubber cushion GC (Figure 9). The measured values, set to an input power of 1W, a measurement distance of 30cm, a frequency range of 124Hz to 80kHz, and a sweep time of 60 seconds, are shown in the graphs in Figures 10a to 10d and Figures 11, 12, and 13.

[0056] As shown in Figures 10a to 10d, while conventional voice coil type vibration speakers show a drop in frequency response from around 10 kHz, the ceramic plate vibration speaker of the present invention extends its frequency response up to around 40 kHz.

[0057] (Regarding plane wave vibrations) Figure 12 shows a comparative graph of auditory distance and sound pressure changes. Figure 12 is a comparison of plane wave effect measurements for ceramic plate-mounted products at 7 kHz, which is necessary for clarity. As shown in Figure 12, with conventional spherical wave speakers, the sound decreases inversely proportional to the square of the distance as the distance from the speaker increases, and at the same time, if the distance is slightly shifted laterally from the front axis, high-frequency sounds are attenuated.

[0058] In contrast, ceramic plate vibration speakers, which use a ceramic plate made of natural fired ceramic consisting of a flat plate-like body as a diaphragm, exhibit plane wave vibration as shown in the upper part of Figure 12. Therefore, the sound attenuates inversely proportional to the first power of the distance, resulting in less attenuation and less angle dependence. Consequently, they have a higher accuracy in reproducing sounds at low sound pressure levels, and in some cases, the speaker volume can be lowered.

[0059] Furthermore, a plane wave speaker with appropriate porosity transmits all sound waves emitted from the diaphragm's surface only forward, resulting in no loss of sound information and creating a sense of realism as if listening in a concert hall. In addition, sufficient energy in the high-frequency range is maintained, making it possible to reproduce ultra-high frequencies up to 60 kHz.

[0060] The ceramic plate speaker using a flat diaphragm of the present invention comprises an actuator (1) having a central hole and facing the direction of vibration transmission, a voice coil positioned near the central hole of the facing portion, an annular magnet hollowly supported near the periphery of the voice coil, and a frame that frames these components. A ceramic diaphragm (2) made by sintering natural ceramic raw materials and forming it into a plate shape to a predetermined thickness, This is a ceramic plate vibration speaker formed by joining components via a transmission ring (106) made of a metal ring.

[0061] The sound vibrations emitted from actuator 1 are transmitted via transmission ring 106 to a diaphragm 2 made of ceramic plate from natural firing material, and sound waves are emitted from the entire flat surface of the diaphragm 2, making it a so-called plane wave speaker. It has the following features in particular.

[0062] 1. The diaphragm, made from naturally fired ceramic tiles, possesses all the necessary elements for a planar wave speaker diaphragm: appropriate strength and internal damping, and a surface treatment material hardened with glaze. This allows for immersive sound reproduction beyond the audible range. Furthermore, it is suitable for display as a work of art.

[0063] 2. The actuator of the present invention transmits sound through this specific ceramic diaphragm only via a metal transmission ring, enabling the reproduction of frequencies from below 50 kHz in the audible frequency range to the ultra-high frequency range of 60 kHz. This is a frequency response equivalent to that of high-end hypersonic speakers, enabling dynamic and delicate sound reproduction with a sense of presence and fidelity.

[0064] Furthermore, the sound vibrations from the flat diaphragm, generated by plane wave vibration, are less susceptible to sound attenuation depending on the auditory position, making it suitable for reproducing the sound when viewing diaphragms decorated with paintings or other artwork.

[0065] The embodiments described above are not limited to the configurations and aspects of each embodiment described above, and various modifications, shapes, and dimensions can be made without impairing the spirit of the invention. For example, the components of the actuator can be integrated, some components can be omitted, the shape and structure of the diaphragm can be modified, the firing layers can be polymerized, an additional layer can be added to the top, or the thickness and porosity of each layer can be adjusted. [Explanation of Symbols]

[0066] 1 Actuator 101 Vibration Space 102 Magnetic Circuit 103 Voice coil (bobbin) 103S Coil width center 104 Fixed plate 105 frame 106 Transmission Ring 106w ring width 107 Vibration plate 108 Bottom Plate 109 Magnets 110 Top Plate 2 diaphragm 2F board surface 2FD glaze layer 20D basic components 2D thickness 21SL, 22SL Plate edge length 21GL, 22GL Mounting dimensions from centroid 2GX centroid position 113R Remote holding distance 112 Remote holding pins 113 Cushioning material

Claims

1. An actuator comprising: an opposing part having a central hole and facing the vibration transmission direction; a voice coil positioned near the central hole of the opposing part; an annular magnet hollow-supported near the periphery of the voice coil; and a frame that frames these components. A diaphragm made of ceramic plate, which is formed into a plate shape to a predetermined thickness by sintering natural ceramic raw materials, A ceramic plate vibration speaker, which is joined via a transmission ring made of a metal ring, The diaphragm has an annular end face of the transmission ring bonded to its plate-shaped back surface, and the vibrations reproduced by the actuator in the audible frequency range and the ultra-high frequency range from 20 kHz to 60 kHz are transmitted solely through this transmission ring as the vibration transmitting material, causing the diaphragm to vibrate in a plane wave from the audible range to the high frequency range, thus forming a ceramic plate vibrating speaker for plane wave high frequency range vibration.

2. The transmission ring consists of a metal cylinder having a uniform annular cross-section. The annular end face at the base end of the cylindrical body makes surface contact with the coil end of the voice coil, The ceramic plate vibrating speaker for plane wave high-frequency vibration according to claim 1, characterized in that the annular end face at the tip of the cylindrical body is fixed to the diaphragm with an annular end face shape having a substantially uniform annular width in the circumferential direction, without having an outward protrusion.

3. A ceramic plate vibrating speaker for plane wave high-frequency vibration according to claim 1, characterized in that the transmission ring is made of a single piece of brass metal and the annular end surface of the tip is fixed to the diaphragm.

4. A ceramic plate vibrating speaker for plane wave high-frequency vibration according to claim 1, characterized in that the thickness of the diaphragm is set to a standard thickness within the range of 2.5 to 22.0 mm, and the thickness variation range is set to ±1.0 mm or less relative to the standard thickness, and the outermost surface within this thickness has a surface layer on which a pattern or relief pattern is displayed.

5. A ceramic plate vibrating speaker for plane wave high-frequency vibration according to claim 1, wherein the thickness of the diaphragm is set to a standard thickness in the range of more than 4.0 mm and less than 20.1 mm, and the porosity of the entire diaphragm is set to the range of 5.0% or more and less than 55.0%.

6. The ceramic plate vibrating speaker for plane wave high frequency vibration according to claim 4, characterized in that the diaphragm has a glaze layer on its surface having a predetermined thickness in the range of more than 1.0 mm to less than 2.0 mm within the range of the plate thickness.

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