CN1946248A - Electrostatic ultrasonic energy exchanger and ultrasonic loudhailer - Google Patents

Abstract

An electrostatic ultrasonic energy exchanger and an ultrasonic loudhailer are provided. The electrostatic ultrasonic energy exchanger fixes the region except from the vibration region of the vibration diaphragm, therefore decreasing the vibrating distortion. In the push-pull type electrostatic ultrasonic energy exchanger (1), a pair of fixed electrodes (10,11) with a plurality of through holes (14) are provided with electrode for vibration (101,111) which vibrating the region facing the through holes (14) as a vibration region and electrodes for fixing (102,112) which fixing the un-vibration region of the vibration diaphragm (12). Applying AC signal between the electrode layer (121) and electrode for vibration (101,111) of the vibration diaphragm (12) makes the vibration region vibrate. Applying DC voltage between the electrode layer (121) and electrode for vibration (102,112) of the vibration diaphragm (12) fixes the un-vibration region by electrostatic force.

Description

Electrostatic ultrasonic transducer and ultrasonic speaker

Technical field

The present invention relates to a kind of electrostatic ultrasonic transducer, particularly can reduce distortion influence etc. and can by the zone to vibrating membrane carry out vibration control electrostatic ultrasonic transducer, use this electrostatic ultrasonic transducer ultrasonic speaker, use voice signal reproducting method, super directive property sound system and the display unit of electrostatic ultrasonic transducer.

Background technology

In the past, as the ultrasonic transducer of electrostatic means, known had a broadband oscillation mode ultrasonic transducer that can produce high sound pressure at whole high-frequency domain.Fig. 7 represents the structure example of the electrostatic ultrasonic transducer of broadband oscillation mode.This electrostatic ultrasonic transducer 3 is owing to only playing a role on the direction that vibrating membrane is pulled to the fixed electrode side, so be called as the type of drawing (Pull type).

Electrostatic ultrasonic transducer 3 shown in Figure 7 adopts the PET dielectrics 131 (insulator) such as (pet resins) of the thickness about 3～10 μ m as vibrating body (vibrating membrane).On the upper surface part of dielectric 131, be formed with top electrode 132 by processing such as evaporations, this top electrode 132 is that the metal forming by aluminium etc. forms, and is provided with the bottom electrode 133 that is formed by brass contiguously at the lower surface portion and the dielectric 131 of dielectric 131.This bottom electrode 133 is connected with lead 152, and is fixed on the substrate 135 that is made of Berlet phenolic resins (Bakelite) etc.

And top electrode 132 is connected with lead 153, and this lead 153 is connected with dc bias power 150.All the time apply the Dc bias of the top electrode absorption usefulness about 50～150V by this dc bias power 150 to top electrode 132, top electrode 132 is attracted to bottom electrode 133 sides.The 151st, signal source.

Dielectric 131 and top electrode 132 and substrate 135 are riveted by housing 130 with quoit 136,137 and 138 and net 139.

In the minute grooves that is formed with on the face of dielectric 131 sides of bottom electrode 133 about a plurality of tens of～hundreds of μ m with heterogeneity shape.Because this minute grooves becomes the space between bottom electrode 133 and the dielectric 131, so the electrostatic capacitance between top electrode 132 and the bottom electrode 133 distributes minor variations takes place.

This minute grooves is at random carried out roughing with file to the surface of bottom electrode 133 with handwork and is formed.In the ultrasonic transducer of electrostatic means, owing to so form the pore size numerous capacitor different with the degree of depth, thus frequency characteristic becomes wide frequency domain (for example, with reference to patent documentation 1,2).

As mentioned above, as the ultrasonic transducer 3 of electrostatic means shown in Figure 7 all the time as producing than the wide frequency domain ultrasonic transducer (drawing type) of high sound pressure and by known in whole broadband.

But the maximum of acoustic pressure is low slightly, for example be that acoustic pressure is low to moderate below the 120dB, and when utilizing as ultrasonic speaker, there is a little deficiency in acoustic pressure.For the parametric effect in the ultrasonic speaker is fully showed, then need the above ultrasonic wave acoustic pressure of 120dB, yet in electrostatic ultrasonic transducer (drawing type), be difficult to reach this numerical value, adopt the macromolecule piezoelectric element of the ceraminator of special PZT (lead zirconate titanate) etc. or PVDF (polyvinylidene fluoride) etc. to produce body as ultrasonic wave.But, because how its material of piezoelectric element all has sharp resonance point, under this resonance frequency, drive, obtain practicality as ultrasonic speaker, so can guarantee that the frequency range of high sound pressure is extremely narrow.The narrow-band of promptly can saying so.

In order to address this is that, electrostatic ultrasonic transducer shown in Figure 84 (special Willing 2004-173946 number) has been proposed at present.This structure is commonly referred to as (Push-Pull) type of recommending, and compares with drawing (Pull) type electrostatic ultrasonic transducer, has the ability that satisfies broadband and high sound pressure simultaneously.

In Fig. 8, the electrostatic ultrasonic transducer 4 of push-pull type has: the pair of stationary electrodes 10,11 that comprises the conductive component that utilizes conductive material formation of performance electrode effect; By the vibrating membrane 12 with electrode layer (conductive layer) 121 of pair of stationary electrodes clamping; The parts (not shown) that keep pair of stationary electrodes 10,11 and vibrating membrane.

Vibrating membrane 12 is made of insulator 120, has the electrode layer 121 that is formed by conductive material, applies the Dc bias of single polarity (positive polarity or negative polarity all can) by 16 pairs of these electrode layers 121 of dc bias power.

And pair of stationary electrodes 10,11 is utilized between signal source 18A, the 18B conductive component to pair of stationary electrodes 10,11 and is applied AC signal at a plurality of through holes that have equal number on vibrating membrane 12 opposed positions (through hole of band ladder) 14.Fixed electrode 10 and electrode layer 121, fixed electrode 11 and electrode layer 121 form capacitor respectively.

In said structure, ultrasonic transducer 4 utilizes the electrode layer 121 of 16 pairs of vibrating membranes 12 of dc bias power to apply the Dc bias of single polarity (being positive polarity in this example).On the other hand, apply AC signal by signal source 18A, 18B to pair of stationary electrodes 10,11.Its result is, the positive half period of the AC signal of exporting from signal source 18A, 18B, fixed electrode 10 is applied positive voltage, and to the surface portion 12A effect electrostatic repulsion of the electrode clamping that is not fixed of vibrating membrane 12, surface portion 12A is drawn downwards in Fig. 8.And at this moment, opposed fixed electrode 11 is applied in negative voltage, is back portion 12B so electrostatic attraction acts on the rear side of the described surface portion 12A of vibrating membrane 12, and back portion 12B is drawn below more in Fig. 8.

Therefore, vibrating membrane 12 is not subjected to electrostatic repulsion and electrostatic repulsion in the same direction by the membrane portions of pair of stationary electrodes 10,11 clampings.This negative half period for the AC signal of exporting from signal source 18A, 18B is also identical, the surface portion 12A of vibrating membrane 12 is acted among Fig. 8 electrostatic attraction towards the top, back portion 12B is acted among Fig. 8 upward electrostatic repulsion, vibrating membrane 12 be not subjected to electrostatic repulsion and electrostatic repulsion in the same direction by the membrane portions of pair of stationary electrodes 10,11 clampings.Like this, change in polarity according to AC signal, vibrating membrane 12 is subjected to electrostatic repulsion and electrostatic repulsion in the same direction, the direction that while electrostatic force works alternately changes, and is the acoustic signal of the sound pressure level of the needed abundance of parametric array effect so can produce the bigger film vibration of acquisition.

This ultrasonic transducer 4 is to vibrate owing to vibrating membrane 12 is subjected to power from pair of stationary electrodes 10,11, so be called as (Push-Pull) type of recommending.The electrostatic ultrasonic transducer 4 of push-pull type is compared with the electrostatic ultrasonic transducer of having only electrostatic attraction to act on the type of drawing (Pull) of vibrating membrane, has the ability that satisfies broadband and high sound pressure simultaneously.

In electrostatic ultrasonic transducer shown in Figure 84, the material of fixed electrode 10,11 is so long as getting final product of conductivity for example can be the monomer structure of SUS or brass, iron, nickel.And, owing to need to realize lightweight, thus to the general expoxy glass resin substrate that uses in the circuit substrate etc. or the paper phenolic group is firm and hard executed desired hole processing after, can utilize nickel or gold, silver, copper etc. to carry out electroplating processes etc.And, during this situation,, processing is implemented to electroplate in the two sides of substrate waits more effective in order to prevent the warpage after the moulding.But, consider insulating properties, the vibrating membrane side that is desirably in each fixed electrode is implemented certain insulation processing.For example, utilize aqueous scolder resist, photosensitive film, photonasty coating material, non-conductive coating, electro-deposition material etc. to form the protuberance of insulation.

; as mentioned above, in the electrostatic ultrasonic transducer of push-pull type, vibrating membrane is applied high-tension Dc bias; fixed electrode is applied alternating voltage, and membrane portions is vibrated by the electrostatic force that acts on fixed electrode-vibrating membrane (gravitation and repulsion) thus.During this situation, in order to realize the vibration of ultrasonic wave frequency band, the aperture that need make oscillating component needs to constitute the transducer that tracing property is higher and output is bigger by a plurality of vibrations of design hole below number mm.

But, in the driving method of said structure, vibrating membrane (zone of electrode from pushing up and down is fixed) vibration force between each vibration hole also works, and vibrating membrane is not the state that is fixed in this zone, distance between each vibration hole produces vibrating membrane the laterally problem of slip takes place more in short-term.Like this, vibrating membrane produces when laterally sliding, and the acoustic signal that is produced by vibrating membrane produces vibration distortion, sound quality deterioration.

Patent documentation 1 TOHKEMY 2000-50387 communique

Patent documentation 2 TOHKEMY 2000-50392 communiques

As mentioned above, in the electrostatic ultrasonic transducer of push-pull type shown in Figure 8, vibrating membrane (zone of electrode from pushing up and down is fixed) vibration force between each vibration hole also works, and vibrating membrane is not the state that is fixed in this zone, distance between each vibration hole produces film the laterally problem of slip takes place more in short-term.Because the horizontal slip of this film produces the problem that vibrating membrane produces the vibration distortion.

Summary of the invention

The present invention proposes in order to address the above problem, its purpose is, electrostatic ultrasonic transducer is provided, use the ultrasonic speaker of this electrostatic ultrasonic transducer, use the voice signal reproducting method of electrostatic ultrasonic transducer, super directive property sound system and display unit, this electrostatic ultrasonic transducer fixes the oscillating component zone (non-vibration zone) in addition of vibrating membrane by only utilizing electrostatic force, improve the mutual independence in the vibration hole of array configurations, can reduce the influence etc. of the vibration distortion of film vibration, and can carry out vibration control by the zone to vibrating membrane, carry out phase control by driving partly in addition, can realize directive property control the vibration hole of array configurations.

The present invention proposes in order to address the above problem, and ultrasonic transducer of the present invention is characterised in that this electrostatic ultrasonic transducer has: the 1st electrode, and it has through hole and a plurality of electrode pattern; The 2nd electrode, it has and paired through hole of the described through hole of described the 1st electrode and a plurality of electrode patterns paired with described electrode pattern; Vibrating membrane, it has electrode layer, and this vibrating membrane is by the pair of electrodes clamping of being made up of described the 1st electrode and the 2nd electrode; And control unit, apply voltage between its electrode layer to the described electrode pattern of described pair of electrodes and described vibrating membrane, under a plurality of drive conditions, drive described vibrating membrane.

According to this structure, in the electrostatic ultrasonic transducer of push-pull type (for example, the electrostatic ultrasonic transducer of push-pull type shown in Figure 1) in, in pair of electrodes (for example with a plurality of through holes, fixed electrode 10,11 shown in Figure 1) goes up the electrode pattern of the corresponding multiple driving function of stacked formation respectively (for example, stacked formation vibration shown in Figure 1 with electrode 101,111 and fixing electrode pattern) with electrode 102,112 etc.And, between the electrode layer of each electrode pattern and vibrating membrane (for example, shown in Figure 1 electrode layer 121), apply the voltage corresponding with driving function.

Thus, in the electrostatic ultrasonic transducer of push-pull type, can make the structure of the electrode pattern of described pair of electrodes form multilayer, can carry out vibration control by the zone vibrating membrane.For example, fix zone (non-vibration zone) beyond the oscillating component of vibrating membrane, can reduce the influence etc. of the distortion of film vibration by only utilizing electrostatic force.

And electrostatic ultrasonic transducer of the present invention is characterised in that described electrode has: the vibration electrode pattern that makes described vibrating membrane vibration; And make described vibrating membrane fixing the use electrode pattern fixing with respect to described pair of electrodes, described control unit is when vibrating described vibrating membrane, to the electrode layer of described vibrating membrane and fixingly apply voltage between with electrode pattern, so that the part of described vibrating membrane is fixed with respect to described pair of electrodes.

According to this structure, in the electrostatic ultrasonic transducer of push-pull type (for example, the electrostatic ultrasonic transducer of push-pull type shown in Figure 1) in, form respectively having on the pair of electrodes of a plurality of through holes (for example, shown in Figure 1 fixed electrode 10,11): the vibration electrode pattern that is used for making oscillating component (vibration area that vibrating membrane and the through hole of the fixed electrode are faced) vibration of vibrating membrane; With the non-vibration part (non-vibration zone) that is used to make vibrating membrane with respect to fixing fixing of described pair of electrodes with electrode pattern (for example, form vibration shown in Figure 1 with electrode 101,111 and the fixing electrode pattern of using electrode 102,112 etc.).And, between the electrode layer of vibrating membrane and vibration are with electrode pattern, apply AC signal, make vibrating membrane vibration, and to the electrode layer of vibrating membrane with fix with electrode pattern between apply direct voltage, the non-vibration zone of vibrating membrane is fixed with respect to described pair of electrodes.

Thus, can only utilize electrostatic force to fix zone (non-vibration zone) beyond the oscillating component of vibrating membrane, can reduce the influence etc. of the distortion of film vibration.

And, electrostatic ultrasonic transducer of the present invention is characterised in that, described vibration is cut apart so that described vibrating membrane is divided into a plurality of with electrode pattern to be driven, described control unit is when driving described vibrating membrane, the phase place of the AC signal that control applies between the electrode layer of described vibrating membrane and described vibration each piece with electrode pattern is so that the phase difference that has regulation respectively between adjacent described.

According to this structure, in the electrostatic ultrasonic transducer of push-pull type, the film oscillating component of vibrating membrane (vibration area of facing with the through hole of fixed electrode in the vibrating membrane) is divided into a plurality of, corresponding each piece is cut apart the vibration electrode pattern.And, carry out the phase control of AC signal according to block unit, with the different acoustic signal of output phase, this AC signal of having carried out phase control is imposed on divided each electrode pattern, carry out from the directive property control of the sound of electrostatic ultrasonic transducer radiation.

Thus, in electrostatic ultrasonic transducer, can realize directive property control.

And electrostatic ultrasonic transducer of the present invention is characterised in that this electrostatic ultrasonic transducer has: electrode, and it has a plurality of electrode patterns, and the surface has jog; Vibrating membrane, it has electrode layer, and this vibrating membrane is maintained at the surface of described electrode; And control unit, apply voltage between its electrode layer to the described electrode pattern of described electrode and described vibrating membrane, under a plurality of drive conditions, drive described vibrating membrane.

According to this structure, in the electrostatic ultrasonic transducer of drawing type (for example, electrostatic ultrasonic transducer of drawing type shown in Figure 4) in, at electrode (for example with a plurality of recesses (or through hole), fixed electrode 11 shown in Figure 4) goes up according to driving the stacked formation electrode pattern of functional type (for example, vibration shown in Figure 4 being formed multilayer with electrode 111 and fixing electrode pattern with electrode 112 grades).And, between the electrode layer of each electrode pattern and vibrating membrane (for example, shown in Figure 4 electrode layer 121), apply the voltage corresponding with driving function.

Thus, in drawing the electrostatic ultrasonic transducer of type, can make the structure of the electrode pattern of pair of electrodes form multilayer, can carry out vibration control by the zone vibrating membrane.For example, fix zone (non-vibration zone) beyond the oscillating component of vibrating membrane, can reduce the influence etc. of the distortion of film vibration by only utilizing electrostatic force.

And electrostatic ultrasonic transducer of the present invention is characterised in that described electrode has: the vibration electrode pattern that makes described vibrating membrane vibration; And make described vibrating membrane fixing the use electrode pattern fixing with respect to described electrode, described control unit is when driving described vibrating membrane, between the electrode layer of described vibrating membrane and fixed electrode are with pattern, apply voltage, so that the part of described vibrating membrane is fixed with respect to described electrode.

According to this structure, in the electrostatic ultrasonic transducer of drawing type (for example, electrostatic ultrasonic transducer of drawing type shown in Figure 4) in, go up and form having the electrode of a plurality of through holes (for example, shown in Figure 4 fixed electrode 11): the vibration electrode pattern that is used for making oscillating component (vibration area that vibrating membrane and the recess of the electrode are faced) vibration of vibrating membrane; With the fixing fixing electrode pattern (for example, forming vibration shown in Figure 4 electrode 111 and the fixing electrode pattern of using electrode 112) of using in non-vibration zone that is used to make vibrating membrane.And, between the electrode layer of vibrating membrane and vibration are with electrode pattern, apply AC signal, make the vibrating membrane vibration, and apply direct voltage, fixedly the non-vibration zone of vibrating membrane to the electrode layer of vibrating membrane and between fixing with electrode pattern.

Thus, can only utilize electrostatic force to fix zone (non-vibration zone) beyond the oscillating component of vibrating membrane, can reduce the influence etc. of the distortion of film vibration.

And, electrostatic ultrasonic transducer of the present invention is characterised in that, described vibration is cut apart so that described vibrating membrane is divided into a plurality of with electrode pattern to be driven, described control unit is when driving described vibrating membrane, the phase place of the AC signal that control applies between the electrode layer of described vibrating membrane and described vibration each piece with electrode pattern is so that the phase difference that has regulation respectively between adjacent described.

According to this structure, in drawing the electrostatic ultrasonic transducer of type, the film oscillating component of vibrating membrane (vibration area of facing with the recess of electrode in the vibrating membrane) is divided into a plurality of, corresponding each piece is cut apart the vibration electrode pattern.And, carry out the phase control of AC signal according to block unit, with the different acoustic signal of output phase, this AC signal of having carried out phase control is imposed on divided each electrode pattern, carry out from the directive property control of the sound of electrostatic ultrasonic transducer radiation.

Thus, in electrostatic ultrasonic transducer, can realize directive property control.

And ultrasonic speaker of the present invention is characterised in that this ultrasonic speaker has aforementioned each described electrostatic ultrasonic transducer.

The ultrasonic speaker of influence of having reduced distortion etc. can be provided thus.And, the ultrasonic speaker that can carry out directive property control can be provided.

And, voice signal reproducting method based on electrostatic ultrasonic transducer of the present invention, it is characterized in that this voice signal reproducting method uses each described electrostatic ultrasonic transducer of front, and comprise the steps: to generate the step of the signal wave of audio-band by signal source; Generate the step of the carrier wave of ultrasonic wave frequency band by the carrier wave supply source; Generation utilizes the signal wave of described audio-band described carrier wave to be carried out the step of the modulation signal of modulation; And, drive the step of described electrostatic ultrasonic transducer by between the electrode layer of described electrode and described vibrating membrane, applying described modulation signal.

In the voice signal reproducting method of the electrostatic ultrasonic transducer that comprises these steps, generate the signal wave of audio-band by signal source, and generate the carrier wave and the output of ultrasonic wave frequency band by the carrier wave supply source.In addition, utilize the signal wave of described audio-band to come modulated carrier, this modulation signal is applied between the electrode layer of electrode and vibrating membrane, thereby drives electrostatic ultrasonic transducer.

Thus, utilize the electrostatic ultrasonic transducer of said structure, can reduce the influence of the distortion of film vibration, and increase the film vibration, can export the acoustic signal that has reduced distortion under broadband, to obtain the needed sufficiently high sound pressure level of parametric array effect, and reproduced sound signal.

And, super directive property sound system of the present invention, the ultrasonic speaker of this system by using above-mentioned each described electrostatic ultrasonic transducer to constitute, the voice signal that reproduction provides from the sound equipment source, near acoustic reflection faces such as screen, form virtual sound source, it is characterized in that this super directive property sound system has: ultrasonic speaker, it reproduces the signal in the alt territory from the voice signal that described sound equipment source provides; And the low-frequency sound reproducing loud speaker, it reproduces the sound of the low range from the voice signal that described sound equipment source provides.

In the super directive property sound system of said structure, use the ultrasonic speaker that utilizes aforementioned each described electrostatic ultrasonic transducer to constitute.And, utilize this ultrasonic speaker to reproduce the voice signal in the alt territory from the voice signal that the sound equipment source provides.Utilize the voice signal of low-frequency sound reproducing with the low range of loudspeaker reproduction from the voice signal that the sound equipment source provides.

Therefore, under the state that can be lowered, have sufficient acoustic pressure and broadband character in the influence of the film of electrostatic ultrasonic transducer vibration, to reproduce the sound equipment in alt territory from being formed at the mode that near the acoustic reflection face such as screen virtual sound source sends the sound equipment in alt territory.And the sound equipment of low range is directly exported with loud speaker from the low-frequency sound reproducing that sound system possesses, so can strengthen low range, builds presence good sound field environment more.

And, display unit of the present invention is characterised in that, this display unit constitutes and comprises each described electrostatic ultrasonic transducer of front, and this display unit has: ultrasonic speaker, and signal sound of audio-band is provided from the voice signal that is provided by the sound equipment source for it; And projection optical system, its with video-projection in the perspective plane.

In the display unit of said structure, use the ultrasonic speaker that constitutes by aforementioned each described electrostatic ultrasonic transducer.And utilize the voice signal that this ultrasonic speaker reproduces to be provided from the sound equipment source.

Thus, can have enough acoustic pressures and broadband character, to reproduce acoustic signal from being formed at the mode that near the acoustic reflection faces such as screen virtual sound source sends acoustic signal.Therefore, can easily carry out the reproduction range control of acoustic signal.And, can carry out from the directive property control of the sound of ultrasonic speaker radiation.

Description of drawings

Fig. 1 is the figure of the 1st execution mode of expression ultrasonic transducer of the present invention.

Fig. 2 is the figure that the signal of expression electrostatic ultrasonic transducer shown in Figure 1 connects example.

Fig. 3 is the figure of the 2nd execution mode of expression ultrasonic transducer of the present invention.

Fig. 4 is the figure of the 3rd execution mode of expression electrostatic ultrasonic transducer of the present invention.

Fig. 5 is the figure of topology example of the directive property of expression control electrostatic ultrasonic transducer.

Fig. 6 is the topology example figure of expression ultrasonic speaker.

Fig. 7 is the figure that the topology example of type electrostatic ultrasonic transducer is drawn in expression.

Fig. 8 is the figure of the topology example of expression push-pull type electrostatic ultrasonic transducer.

Fig. 9 is the figure of the user mode of the projecting apparatus that relates to of expression embodiments of the present invention.

Figure 10 is the figure of the surface structure of expression projecting apparatus shown in Figure 12.

Figure 11 is the block diagram of the electric structure of expression projecting apparatus shown in Figure 12.

Figure 12 is based on the key diagram of playback mode of the reproducing signal of ultrasonic transducer.

Label declaration

1,2,3,4 electrostatic ultrasonic transducer; 10,11 fixed electrodes; 12 vibrating membranes; The 12A surface portion; The 12B back portion; 13A, 13B electrode matrix parts; 14 through holes (through hole of band ladder); 16 dc bias powers; 18A, 18B signal source; 19,20 DC power supply; 21A, 21B, 21C, 21D are cut apart electrode pattern; 22 sound wave emitting surfaces; 30 ultrasonic speakers; 31 audible frequency ripple signal oscillating sources; 32 carrier signal sources; 33 modulators; 34 power amplifiers; 35 electrostatic ultrasonic transducer; 101,111 vibration electrodes; 102, the 112 fixing electrodes of using; 120 insulators; 121 electrode layers; 301 projecting apparatus; 302 screens (perspective plane); 303 look the hearer; 310 operation inputting part; 312 reproduction range configuration parts; 313 reproduction range control and treatment portions; 314 sound/vision signal recapiulation; 316 carrier oscillation sources; 317A, 317B high pass filter; 318A, 318B modulator; 319 low pass filters; 320 projecting apparatus bodies; 321 adders; 322A, 322B, 322C power amplifier; 323 low-frequency sound reproducing loud speakers; 324A, 324B electrostatic ultrasonic transducer; 331 projector lens; 332 video generating units; 333 projection optical systems.

Embodiment

(the 1st execution mode)

Fig. 1 is the figure of the 1st execution mode of expression ultrasonic transducer of the present invention.Example shown among Fig. 1 is applied to the present invention the example of the electrostatic ultrasonic transducer of push-pull type.Fig. 1 (A) is the integrally-built figure of the electrostatic ultrasonic transducer of expression push-pull type.The structure of the electrostatic ultrasonic transducer 1 shown in Fig. 1 (A) is identical with the electrostatic ultrasonic transducer shown in Figure 8 that illustrates previously basically.But, in ultrasonic transducer shown in Figure 1, on fixed electrode 10,11, be formed with a plurality of electrode patterns, and, fix with electrode 10,11 and utilize insulating material to constitute in order to form a plurality of electrode patterns.

Fig. 1 (B) is the partial enlarged drawing of Fig. 1 (A), and a plurality of electrode patterns are shown configuration vibration electrode and fixing example with electrode.And Fig. 1 (C) is expression vibration with the figure of electrode and fixing configuration relation with electrode, is top from Fig. 1 figure when watching electrostatic ultrasonic transducer 1.

Shown in Fig. 1 (B), in the electrostatic ultrasonic transducer 1 of push-pull type, on the fixed electrode 10 of upside, vibration is configured to respectively vibrate hole shape (through hole is arranged) with electrode 101, as an electrode pattern preparing to connect them.That is, the inside of the through hole of fixed electrode 10 (through hole of band ladder) 14, be formed on the banded circumferentia 14A through hole 14 in configuration vibration usefulness electrode 101 because of the ladder difference of small-bore and wide-aperture through hole.This vibration forms the electrode pattern of ring-type shown in Fig. 1 (C) with electrode 101.In addition, the band-like portions 101A that extends with electrode 101 from vibration becomes the part that the wiring pattern of electrode 101 is used in the vibration that connects adjacent through hole 14.

And the part outside the through hole 14 of the fixed electrode 10 of upside is not disposing fixing usefulness electrode 102 with vibration with electrode 101 position contacting.Vibration is with electrode 101 and fixingly do not dispose at grade with electrode 102, but with the form separate configuration that clips insulating material on last lower plane.Equally, on the fixed electrode 11 of downside, dispose vibration with electrode 111 in the part of through hole 14, the part outside through hole 14 disposes fixing with electrode 112.Vibration is with electrode 111 and fixingly do not dispose at grade with electrode 112, but with the form separate configuration that clips insulating material on last lower plane.By forming this structure, vibration is with electrode 101,111 and fixing independent respectively with electrode 102,112, can partly separate to constitute vibration and use and the fixedly driving of usefulness.

In addition, electrode matrix parts 13A that is provided with at the upper surface of electrostatic ultrasonic transducer 1 and the electrode matrix parts 13B that is provided with at lower surface are to cover and the matrix part of protection fixed electrode 10,11, do not have direct relation with action of the present invention.

Fig. 2 is the figure that the signal of expression electrostatic ultrasonic transducer shown in Figure 1 connects example.Connect shown in the example as the signal among Fig. 2, the fixing fixing electrode of using in the electrode 10 102 of using at upside, utilize the electrode layer 121 of 19 pairs of vibrating membranes 12 of DC power supply to apply the direct voltage of single polarity (being positive polarity in this example), fixing with electrode 112 in the fixed electrode 11 of downside utilizes the electrode layer 121 of 20 pairs of vibrating membranes 12 of DC power supply to apply the direct voltage of single polarity (being positive polarity in this example).Thus, the electrode layer 121 of vibrating membrane 12 and fixing with electrode 102 between electrostatic attraction work, at the electrode layer 121 of vibrating membrane 12 and also be that electrostatic attraction works between fixing with electrode 112.Therefore, can utilize electrostatic force that the non-vibration zone of vibrating membrane 12 is fixed on the fixed electrode 10,11.

And, use between the electrode 101,102 in the electrode layer 121 and the vibration of vibrating membrane 12, utilize dc bias power 16 to apply the Dc bias of single polarity (being positive polarity in this example).And, imposing on vibration with electrode 101 with the state of the Dc bias that superposeed from the AC signal of signal source 18A output.Equally, imposing on vibration with electrode 111 with the state of the Dc bias that superposeed from the AC signal of signal source 18B output.

The result, during positive half period of the AC signal of exporting from signal source 18A, 18B, vibration is applied in positive voltage with electrode 101, so electrostatic repulsion acts on the surface portion 12A of the electrode clamping that is not fixed of vibrating membrane 12, below surface portion 12A is pulled in Fig. 2.

And opposed vibration this moment is applied in negative voltage with electrode 111, is back portion 12B so electrostatic attraction acts on the rear side of the described surface portion 12A of vibrating membrane 12, below back portion 12B is pulled to more in Fig. 2.Therefore, vibrating membrane 12 is not subjected to electrostatic repulsion and electrostatic repulsion in the same direction by the membrane portions of pair of stationary electrodes 10,11 clampings.

This negative half period for the AC signal of exporting from signal source 18A, 18B is also identical, electrostatic attraction acts on the surface portion 12A of vibrating membrane 12 towards the top among Fig. 2, electrostatic repulsion acts on back portion 12B towards the top among Fig. 2, vibrating membrane 12 be not subjected to electrostatic repulsion and electrostatic repulsion in the same direction by the membrane portions of pair of stationary electrodes 10,11 clampings.

Like this, change in polarity according to AC signal, vibrating membrane 12 is subjected to electrostatic repulsion and electrostatic repulsion at equidirectional, the direction that while electrostatic force works alternately changes, so can produce the vibration of bigger film, promptly produce the acoustic signal that obtains the needed enough sound pressure level of parametric array effect.

As described above, in the 1st execution mode shown in Figure 1, utilize the fixedly zone outside the vibration section of vibrating membrane 12 of electrostatic force, the mutual independence in the vibration hole (vibration area of facing with the through hole 14 of fixed electrode in the vibrating membrane) of array configurations can be improved, the influence of distortion etc. can be reduced.

In addition, be applied to vibrating membrane 12 and fixing value by increase and decrease with the direct voltage between the electrode 102,112, can increase and decrease the electrode layer 121 and the fixing electrostatic force of using between the electrode 102,112 that are applied to vibrating membrane 12, can make the periphery of the film oscillating component of vibrating membrane 12 become free end, can increase the film vibration thus from stiff end.

(the 2nd execution mode)

In addition, Fig. 3 is the figure of the 2nd execution mode of expression electrostatic ultrasonic transducer of the present invention.Example among Fig. 3 is compared with the 1st execution mode shown in Figure 1, is to make the fixing example that more disposes near vibrating membrane 12 with the position of electrode 102,112.Like this, it is fixing with electrode 102,112 and vibrating membrane 12 needed direct voltages to reduce to utilize electrostatic force to fix.

(the 3rd execution mode)

In electrostatic ultrasonic transducer of the present invention, can not rely on the electrostatic ultrasonic transducer of push-pull type, also can utilize the electrostatic ultrasonic transducer of the type of drawing to realize.

Fig. 4 is the figure of the 3rd execution mode of expression electrostatic ultrasonic transducer of the present invention, is the example that constitutes the electrostatic ultrasonic transducer of the type of drawing.

Fig. 4 (A) is the integrally-built figure of expression electrostatic ultrasonic transducer 2.Fig. 4 (B) is the partial enlarged drawing of Fig. 4 (A), expression vibration electrode and fixing ios dhcp sample configuration IOS DHCP with electrode.And Fig. 4 (C) is the figure that the expression signal connects example, and Fig. 4 (D) is the figure of the variation of expression fixed electrode 11.

Being exemplified as among Fig. 4 removed the fixing topology example with electrode 10 parts of the upside of electrostatic ultrasonic transducer 1 shown in Figure 1.And, compare with ultrasonic transducer 3 shown in Figure 7, form the structure that the recess with fixed electrode 133 of jog shown in Figure 7 is replaced into through hole 14 shown in Figure 4.By forming this structure, improved air circulation based on through hole 14, can improve emission efficiency from the acoustic signal of vibrating membrane 12.In addition, fixed electrode 11 shown in Figure 4 is formed carry out structure shown in Fig. 4 (D) that the displacement identical with the fixed electrode with jog shown in Figure 7 133 obtain.

In addition, the fixing electrode 10 of using of the upside that being exemplified as among Fig. 4 removed electrostatic ultrasonic transducer 1 shown in Figure 1, form the electrostatic ultrasonic transducer of the type of drawing, vibration with electrode 111, fix with the function of electrode 112 and move same as shown in Figure 1, so omit its explanation.

(the 4th execution mode)

In electrostatic ultrasonic transducer of the present invention, on fixed electrode,, can apply the voltage corresponding to each electrode pattern, so can carry out vibration control according to the zone to vibrating membrane with driving function according to driving function setting multi-layered electrode pattern.

Therefore, the oscillating component (vibration area of facing with the through hole of fixed electrode in the vibrating membrane) of the vibrating membrane of being arranged to array-like of fixed electrode is divided into a plurality of, carry out the phase control of AC signal according to block unit, with the different acoustic signal of output phase, the control of the directive property of the sound that can radiate.

Fig. 5 is the figure of topology example of the directive property of expression control electrostatic ultrasonic transducer.In the example of Fig. 5, the vibration corresponding with the oscillating component 15 of vibrating membrane is divided into four electrode pattern 21A, 21B, 21C, 21D with electrode, the phase place of the AC signal of each electrode pattern is lagged behind in the direction of arrow A.Thus, can make from the wave surface of the acoustic signal of sound wave emitting surface 22 radiation to tilt, have directive property towards arrow B (direction the accompanying drawing).

(the 5th execution mode)

Below, the topology example of the ultrasonic speaker that has used Fig. 1, Fig. 3, Fig. 4 and ultrasonic transducer shown in Figure 5 is described.

Fig. 6 is the general topology example figure that the ultrasonic speaker of electrostatic ultrasonic transducer of the present invention has been used in expression.Ultrasonic speaker utilizes audio signal (zone of audibility signal) that the ultrasonic wave that is called as carrier wave is applied AM modulation, when it being emitted to when aerial, utilizes the non-linear of air that original audio signal is reproduced voluntarily aloft.Promptly, sound wave is the dilatational wave that air is propagated as medium, so in the process that modulated ultrasonic wave is propagated, dividing than the compact part branch with than part of rarefaction of air obviously shows, and be fast than the velocity of sound that compact part divides, slack-off than the velocity of sound that part of rarefaction divides, so modulating wave self produces distortion, the result, waveform is separated into carrier wave (ultrasonic wave) and can listens ripple (former audio signal), people can only hear the sub-audible sound (former audio signal) that 20kHz is following, and this principle is commonly referred to as the parametric array effect.

Ultrasonic speaker 30 shown in Figure 6 has: the audible frequency ripple signal oscillating source (audio signal source) 31 that generates the signal wave of audio-band; Generate the carrier wave of ultrasonic wave frequency band and the carrier signal source 32 of output; Modulator 33; Power amplifier 34; With ultrasonic transducer 35.

Modulator 33 utilizes the signal wave of listened to the ripple frequency band of 31 outputs from audible frequency ripple signal oscillating source to modulate the carrier wave of 32 outputs from the carrier signal source, offers ultrasonic transducer 35 by power amplifier 34.

In said structure, modulator 33 utilizes the audio signal ripple of 31 outputs from audible frequency ripple signal oscillating source to modulate the carrier wave of the ultrasonic wave frequency band of 32 outputs from the carrier signal source, utilizes the modulation signal that amplifies via power amplifier 34 to drive ultrasonic transducer 35.As a result, above-mentioned modulation signal is converted into the sound wave of finite amplitude level by ultrasonic transducer 35, and this sound wave emits to (in the air) in the medium, by means of the non-linear effect of medium (air), reproduces the signal sound of original audio-band voluntarily.Promptly, sound wave is the dilatational wave that air is propagated as medium, so in the process that modulated ultrasonic wave is propagated, dividing than the compact part branch with than part of rarefaction of air obviously shows, and be fast than the velocity of sound that compact part divides, slack-off than the velocity of sound that part of rarefaction divides, so modulating wave self produces distortion, as a result, separate, can listen the signal wave (signal sound) of ripple frequency band reproduced with carrier wave (ultrasonic wave frequency band) waveform.

In addition, use shown in Figure 5, when the ultrasonic transducer of local phase control is carried out in the driving of the oscillating component (vibration area of facing with the through hole of fixed electrode in the vibrating membrane) of array configurations, in power amplifier 34, comprise following circuit, this circuit makes the phase place phase shift according to divided each electrode pattern, and amplifies.

As described above, in electrostatic ultrasonic transducer of the present invention, the structure of the electrode pattern by making fixed electrode is a multilayer, can carry out vibration control according to the zone to vibrating membrane.For example, fix zone outside the oscillating component of vibrating membrane, can improve the mutual independence of the oscillating component of array configurations, can reduce the influence of distortion etc. by only utilizing electrostatic force.And,, can realize directive property control by the driving of the oscillating component of array configurations being carried out local phase control.

(explanation of the topology example of super directive property sound system of the present invention)

Below, the super directive property sound system that has used the ultrasonic speaker that utilizes electrostatic ultrasonic transducer formation of the present invention is described, wherein, this electrostatic ultrasonic transducer is the electrostatic ultrasonic transducer of push-pull type, has: the 1st electrode that is formed with through hole; Be formed with the 2nd electrode with the paired through hole of the through hole of described the 1st electrode; Vibrating membrane, it by described pair of electrodes clamping and has an electrode layer, by this electrode layer being applied Dc bias and to applying AC signal between the described pair of electrodes and between described pair of electrodes and the described electrode layer, this vibrating membrane is driven; With the holding member that keeps described pair of electrodes and described vibrating membrane, in the stacked formation and the corresponding electrode pattern of multiple driving function respectively of described the 1st, the 2nd electrode, the electrostatic ultrasonic transducer of described push-pull type has control unit, this control unit is controlled, between the electrode layer of the electrode pattern of described stacked formation and described vibrating membrane, to apply the voltage corresponding with the drive condition of stipulating described driving function, perhaps described electrostatic ultrasonic transducer is the electrostatic ultrasonic transducer of drawing type, has: the surface has the electrode of jog; Vibrating membrane, it is located at the surface of described electrode and has an electrode layer, is driven by this electrode layer being applied Dc bias and apply AC signal between the electrode layer of described vibrating membrane and described electrode; With the parts that keep described electrode and vibrating membrane, on described electrode according to driving the stacked formation electrode pattern of function, described electrostatic ultrasonic transducer of drawing type has control unit, this control unit is controlled, to apply the voltage corresponding with the drive condition of stipulating described driving function between the electrode layer of the electrode pattern of described stacked formation and described vibrating membrane.

Below, as an example of the super directive property sound system that the present invention relates to, be that example describes with the projecting apparatus.In addition, the super directive property sound system that the present invention relates to is not limited to projecting apparatus, also can be widely used in carrying out the display unit of the reproduction of sound and video.

Fig. 9 represents the user mode of the projecting apparatus that the present invention relates to.As shown in the drawing, projecting apparatus 301 is arranged on the rear of looking hearer 303, is being arranged at projection video on the screen 302 of looking hearer 303 the place aheads, and utilizes the ultrasonic speaker that is installed on the projecting apparatus 301, on the perspective plane of screen 302, form virtual sound source, and reproduce sound.

Figure 10 A and Figure 10 B represent the surface structure of projecting apparatus 301.Projecting apparatus 301 constitutes and comprises: comprise the projector main body 320 with the projection optical system of video-projection on perspective planes such as screen; With ultrasonic transducer 324A, the 324B of the sonication that can make the ultrasonic wave frequency band, and constitute one with the ultrasonic speaker that the signal sound of audio-band is provided from the voice signal that provides by the sound equipment source.In the present embodiment, for the reproduction of stereo sound signal, about on the projector main body, ultrasonic transducer 324A, the 324B that constitutes ultrasonic speaker has been installed across the projector lens 331 that constitutes projection optical system.

In addition, be provided with low-frequency sound reproducing loud speaker 323 in the bottom surface of projector main body 320.And the height set screw of the Height Adjustment of projector main body 320 is carried out in 325 expressions, the exhaust outlet that 326 expression air cooling fans are used.

In projecting apparatus 301, the electrostatic ultrasonic transducer of using push-pull type of the present invention is as the ultrasonic transducer that constitutes ultrasonic speaker, and can vibrate under high sound pressure produces the acoustic signal (sound wave of ultrasonic wave frequency band) of wide frequency domain.Therefore, control the reproducing signal reproduction range spatially of audio-band by the frequency that changes carrier wave, thereby do not need the necessary large-scale sound system of prior art just can realize the acoustics that can obtain by stereo surround system or 5.1ch surrounding system etc., and can be easy to carrying.

Next, Figure 11 represents the electric structure of projecting apparatus 301.Projecting apparatus 301 has: operation inputting part 310; Ultrasonic speaker, it comprises reproduction range configuration part 312, reproduction range control and treatment portion 313, sound/vision signal recapiulation 314, carrier oscillation source 316, modulator 318A, 318B, power amplifier 322A, 322B, electrostatic ultrasonic transducer 324A, 324B; High pass filter 317A, 317B; Low pass filter 319; Adder 321; Power amplifier 322C; Low-frequency sound reproducing loud speaker 323; And projector main body 320.And electrostatic ultrasonic transducer 324A, 324B are the electrostatic ultrasonic transducer of push-pull type of the present invention.

Projector main body 320 has: generate the video generating unit 332 of video, with the video-projection that the generates projection optical system 333 to the perspective plane.Projecting apparatus 301 is integrated and constitute with loud speaker 323 and projector main body 320 with ultrasonic speaker, low-frequency sound reproducing.

Operation inputting part 310 has various function keys, comprising ten key, numerical key, be used to carry out the power key of mains switch.The data that button operation input is used to specify the reproduction range of reproducing signal (signal tone) can be carried out to operation inputting part 310 by the user in reproduction range configuration part 312, after importing these data, just set and preserved the frequency of carrier wave of the reproduction range of regulation reproducing signal.The setting of the reproduction range of reproducing signal is by specifying reproducing signal to carry out along radiation direction of principal axis institute reach from the sound wave emitting surface of ultrasonic transducer 324A, 324B.

Reproduction range configuration part 312 can be according to setting the frequency of carrier wave by sound/control signal that vision signal recapiulation 314 is exported corresponding to video content.

Reproduction range control and treatment portion 313 has following function: with reference to the setting content of reproduction range configuration part 312, and control carrier oscillation source 316, thus become the reproduction range that sets so that change the frequency of the carrier wave that generates by carrier oscillation source 316.

For example, when having set the above-mentioned distance corresponding with carrier frequency 50kHz as the internal information of reproduction range configuration part 312, control carrier oscillation source 316 makes it vibrate with 50kHz.

Reproduction range control and treatment portion 313 has storage part, its stored in advance carrier frequency with stipulated reproduction range, the form of reproducing signal from the sound wave emitting surface of ultrasonic transducer 324A, 324B along the relation of radiation direction of principal axis institute reach.The data of this form are that the relation by the arrival distance of the frequency of actual measurement carrier wave and above-mentioned reproducing signal obtains.

Reproduction range control and treatment portion 313 setting contents according to reproduction range configuration part 312, the frequency of the corresponding carrier wave of range information of trying to achieve and setting with reference to above table, control carrier oscillation source 316 is to become this frequency.

Sound/vision signal recapiulation 314 is for example to adopt the DVD player of DVD as video media, the voice signal of the R channel in the voice signal that reproduces outputs to modulator 318A by high pass filter 317A, the voice signal of L channel outputs to modulator 318B by high pass filter 317B, and vision signal outputs to the video generating unit 332 of projector main body 320.

Synthetic from the sound/voice signal of the R channel that vision signal recapiulation 314 is exported and the voice signal of L channel by adder 321, be input to power amplifier 322C by low pass filter 319.Sound/vision signal recapiulation 314 is equivalent to the sound equipment source.

High pass filter 317A, 317B have the characteristic that the frequency component in the alt territory in the voice signal that only makes R channel, L channel is respectively passed through, and low pass filter has the characteristic that the frequency component of the low range in the voice signal that only makes R channel, L channel is respectively passed through.

Therefore, the voice signal in the alt territory in the voice signal of above-mentioned R channel, L channel reproduces by ultrasonic transducer 324A, 324B respectively, and the voice signal of the low range in the voice signal of above-mentioned R channel, L channel reproduces with loud speaker 323 by low-frequency sound reproducing.

Sound/vision signal recapiulation 314 is not limited to DVD player, so long as will get final product from the transcriber that the vision signal of outside input is reproduced.And, sound/vision signal recapiulation 314 has following function: to the control signal of reproduction range configuration part 312 output indication reproduction ranges, so that dynamically change the reproduction range of reproduction sound for the corresponding acoustics of scene of the video exporting and will reproduce.

Carrier oscillation source 316 has the carrier wave of generation by the frequency of the ultrasonic wave frequency band of reproduction range configuration part 312 indications, and this carrier wave is exported to the function of modulator 318A, 318B.

Modulator 318A, 318B have following function: with from the voice signal of the audio-band of sound/vision signal recapiulation 314 outputs to 316 carrier waves of supplying with carry out the AM modulation from the carrier oscillation source, and export this modulation signal to power amplifier 322A, 322B respectively.

Ultrasonic transducer 324A, 324B are driven by the modulation signal of power amplifier 322A, 322B output from modulator 318A, 318B respectively, has following function: this modulation signal is transformed into the sound wave of finite amplitude level and is transmitted in the medium signal sound (reproducing signal) of reproduction audio-band.

Video generating unit 332 has: LCD, plasma display displays such as (PDP); With the drive circuit that drives this display according to the vision signal from 314 outputs of sound/vision signal recapiulation etc., this video generating unit 332 generates the video that obtains by from the vision signal of sound/vision signal recapiulation 314 outputs.

Projection optical system 333 has the function of video-projection to the perspective planes such as screen that are arranged at projector main body 320 the place aheads that will be presented on the display.

Next, the action to the projecting apparatus 301 that is made of said structure describes.At first, the button operation by the user is set the data (range information) of the reproduction range of indication reproducing signal from operation inputting part 310 reproduction range configuration part 312, sound/vision signal recapiulation 314 is reproduced indication.

Its result is, in reproduction range configuration part 312, set the range information of regulation reproduction range, reproduction range control and treatment portion 313 is taken into the range information that is set in the reproduction range configuration part 312, with reference to the form that is stored in the built-in storage part, try to achieve the frequency with the corresponding carrier wave of range information of above-mentioned setting, control carrier oscillation source 316 generates the carrier wave of these frequencies.

Its result is that carrier oscillation source 316 generates the carrier wave of the corresponding frequency of range information that sets with reproduction range configuration part 312, and exports modulator 318A, 318B to.

On the one hand, sound/vision signal recapiulation 314 outputs to modulator 318A with the voice signal of the R channel in the voice signal that reproduces by high pass filter 317A, the voice signal of L channel is outputed to modulator 318B by high pass filter 317B, export the voice signal of R channel and the voice signal of L channel to adder 321, vision signal is exported to the video generating unit 332 of projector main body 320.

Therefore, by high pass filter 317A the voice signal in the alt territory in the voice signal of above-mentioned R channel is input to modulator 318A, the voice signal in the alt territory in the voice signal of above-mentioned L channel is input to modulator 318B by high pass filter 317B.

The voice signal of the voice signal of above-mentioned R channel and L channel is synthetic by adder 321, by the voice signal input power amplifier 322C of low pass filter 319 with the low range in the voice signal of the voice signal of above-mentioned R channel and L channel.

In video generating unit 332,, generate and display video according to the vision signal driving display of input.Be presented on this display video by projection optical system 333 be projected in the perspective plane, for example on the screen 302 shown in Figure 11.

On the other hand, modulator 318A carries out the AM modulation with the voice signal in the alt territory from the voice signal of the above-mentioned R channel of high pass filter 317A output to the carrier waves of 316 outputs from the carrier oscillation source, and exports power amplifier 322A to.

And modulator 318B carries out the AM modulation with the voice signal in the alt territory from the voice signal of the above-mentioned L channel of high pass filter 317B output to the carrier waves of 316 outputs from the carrier oscillation source, and exports power amplifier 322B to.

The modulation signal that is amplified by power amplifier 322A, 322B is applied to respectively between the top electrode 10A and bottom electrode 10B (with reference to Fig. 1) of ultrasonic transducer 324A, 324B, this modulation signal is transformed into the sound wave (acoustic signal) of finite amplitude level, emit to medium (in the air), reproduce the voice signal in the alt territory the voice signal of above-mentioned R channel from ultrasonic transducer 324A, reproduce the voice signal in the alt territory the voice signal of above-mentioned L channel from ultrasonic transducer 324B.

Reproduce with loud speaker 323 by low-frequency sound reproducing by the above-mentioned R channel of power amplifier 322C amplification and the voice signal of the low range in the L channel.

As mentioned above, in the hyperacoustic propagation that emits to (in the air) in the medium by ultrasonic transducer, follow this propagation, the part velocity of sound high in acoustic pressure accelerates, and be slack-off in the part velocity of sound that acoustic pressure is low.Its result produces the distortion of waveform.

When the signal that utilizes audio-band is modulated (AM modulation) to the signal (carrier wave) of the ultrasonic wave frequency band of radiation, the result of above-mentioned wave distortion is, the carrier separation of the signal wave of used audio-band and ultrasonic wave frequency band during modulation is with the form formation of self-demodulation.At this moment, the diffusion of reproducing signal is owing to Ultrasonic characteristics is the wave beam shape, only with the diverse specific direction of common loud speaker on reproduce sound.

From the reproducing signal of the wave beam shape of ultrasonic transducer 324 outputs that constitute ultrasonic speaker,, be projected the face reflection and spread towards perspective plane (screen) emission by projection optical system 333 projection videos.In this case, frequency according to the carrier wave of setting in the reproduction range configuration part 312, different from the sound wave surface of emission of ultrasonic transducer 324 to go up the distance and the beamwidth (angle of flare of wave beam) of carrier wave of reproducing signal till the carrier separation in its emission shaft direction (normal direction), so reproduction range changes.

Figure 12 represents to comprise ultrasonic transducer 324A, 324B in the projecting apparatus 301 and the ultrasonic speaker that the constitutes state when reproducing reproducing signal.In projecting apparatus 301, utilizing when driving ultrasonic transducer with the modulation signal of voice signal after with carrier modulation, when the carrier frequency of being set by reproduction range configuration part 312 is low, from the sound wave surface of emission of ultrasonic transducer 324 to going up reproducing signal in its emission shaft direction (normal direction of the sound wave surface of emission) from the distance till the carrier separation, promptly elongated to the distance of reproducing the place.

Therefore, the wave beam diffusion of the reproducing signal of the audio-band of reproducing does not arrive perspective plane (screen) 302 not bigly, under this state, 302 reflections on the perspective plane, so reproduction range is the range of audibility A shown in the dotted arrow among Figure 12, only in the far away and narrower scope in perspective plane 302, can hear reproducing signal (reproduction sound).

To this, when the carrier frequency of being set by reproduction range configuration part 312 is higher than said circumstances, compare when the sound wave of launching from the sound wave surface of emission of ultrasonic transducer 324 is low with carrier frequency more concentrated, but from the sound wave surface of emission of ultrasonic transducer 324 to going up reproducing signal in its emission shaft direction (normal direction of the sound wave surface of emission) from the distance till the carrier separation, promptly shorten to the distance of reproducing the place.

Therefore, the wave beam of the reproducing signal of the audio-band of reproducing is diffusion before arriving perspective plane 302, arrive perspective plane 302,302 reflections under this state on the perspective plane, so reproduction range is the range of audibility B shown in Figure 14 solid arrow, only in the scope of and broad nearer, can hear reproducing signal (reproduction sound) from perspective plane 302.

As described above, in projecting apparatus of the present invention, utilization has been used push-pull type of the present invention or has been drawn the ultrasonic speaker of the electrostatic ultrasonic transducer of type, can have enough acoustic pressures and broadband character, to reproduce acoustic signal from being formed at the mode that near the acoustic reflection faces such as screen virtual source of sound sends acoustic signal.Therefore, can easily carry out the control of its reproduction range.And, with electrostatic ultrasonic transducer according to noted earlier, the vibration area of vibrating membrane is divided into a plurality of, the electrode layer and the vibration that are applied to above-mentioned vibrating membrane are carried out drive controlling with the phase place of the AC signal between each piece of electrode pattern, so that have the phase difference of regulation between the adjacent piece respectively, can carry out thus from the directive property control of the sound of ultrasonic speaker radiation.

Embodiments of the present invention more than have been described, but electrostatic ultrasonic transducer of the present invention and ultrasonic speaker are not limited to above-mentioned illustrative example, certainly carry out various changes without departing from the spirit and scope of the present invention.

The ultrasonic transducer that embodiments of the present invention relate to can be used for various transducers, and distance measuring sensor etc. for example, and as previously described can be used for sound source that directional loudspeaker uses and desirable pulse signal generation source etc.And, also very useful to display unit such as super directive property sound system and projecting apparatus.

Claims (10)

1. an electrostatic ultrasonic transducer is characterized in that, this electrostatic ultrasonic transducer has:

The 1st electrode, it has through hole and a plurality of electrode pattern;

The 2nd electrode, it has and paired through hole of the described through hole of described the 1st electrode and a plurality of electrode patterns paired with described electrode pattern;

Vibrating membrane, it has electrode layer, and this vibrating membrane is by the pair of electrodes clamping of being made up of described the 1st electrode and the 2nd electrode; And

Control unit applies voltage between its electrode layer to the described electrode pattern of described pair of electrodes and described vibrating membrane, drives described vibrating membrane under a plurality of drive conditions.

2. electrostatic ultrasonic transducer according to claim 1 is characterized in that,

Described electrode has: the vibration electrode pattern that makes described vibrating membrane vibration; And make described vibrating membrane fixing the use electrode pattern fixing with respect to described pair of electrodes,

Described control unit when making the vibration of described vibrating membrane, to the electrode layer of described vibrating membrane with fix with electrode pattern between apply voltage so that the part of described vibrating membrane is fixed with respect to described pair of electrodes.

3. electrostatic ultrasonic transducer according to claim 2 is characterized in that, described vibration is cut apart with electrode pattern so that described vibrating membrane is divided into a plurality of to be driven,

Described control unit is when driving described vibrating membrane, and the phase place of the AC signal that control applies between the electrode layer of described vibrating membrane and described vibration each piece with electrode pattern is so that the phase difference that has regulation respectively between adjacent described.

4. an electrostatic ultrasonic transducer is characterized in that, this electrostatic ultrasonic transducer has:

Electrode, it has a plurality of electrode patterns, and the surface has jog;

Vibrating membrane, it has electrode layer, and this vibrating membrane is maintained at the surface of described electrode; And

Control unit applies voltage between its electrode layer to the described electrode pattern of described electrode and described vibrating membrane, drives described vibrating membrane under a plurality of drive conditions.

5. electrostatic ultrasonic transducer according to claim 4 is characterized in that,

Described electrode has: the vibration electrode pattern that makes described vibrating membrane vibration; And make described vibrating membrane fixing the use electrode pattern fixing with respect to described electrode,

Described control unit when driving described vibrating membrane, to the electrode layer of described vibrating membrane with fix with electrode pattern between apply voltage so that the part of described vibrating membrane is fixed with respect to described electrode.

6. electrostatic ultrasonic transducer according to claim 5 is characterized in that, described vibration is cut apart with electrode pattern so that the vibration area of described vibrating membrane is divided into a plurality of to be driven,

Described control unit is when driving described vibrating membrane, and the phase place of the AC signal that control applies between the electrode layer of described vibrating membrane and described vibration each piece with electrode pattern is so that the phase difference that has regulation respectively between adjacent described.

7. a ultrasonic speaker is characterized in that, this ultrasonic speaker has each described electrostatic ultrasonic transducer in the claim 1～6.

8. the voice signal reproducting method based on electrostatic ultrasonic transducer is characterized in that, this voice signal reproducting method uses each described electrostatic ultrasonic transducer in the claim 1～6, and comprises the steps:

Generate the step of the signal wave of audio-band by signal source;

Generate the step of the carrier wave of ultrasonic wave frequency band by the carrier wave supply source;

Generation utilizes the signal wave of described audio-band described carrier wave to be carried out the step of the modulation signal of modulation; And

By between the electrode layer of described electrode and described vibrating membrane, applying described modulation signal, drive the step of described electrostatic ultrasonic transducer.

9. super directive property sound system, this system is by using the ultrasonic speaker that each described electrostatic ultrasonic transducer constitutes in the claim 1～6, the voice signal that reproduction provides from the sound equipment source, near acoustic reflection faces such as screen, form virtual sound source, it is characterized in that this super directive property sound system has:

Ultrasonic speaker, it reproduces the signal in the alt territory from the voice signal that described sound equipment source provides; And

The low-frequency sound reproducing loud speaker, it reproduces the sound of the low range from the voice signal that described sound equipment source provides.

10. a display unit is characterized in that, this display unit constitutes and comprises each described electrostatic ultrasonic transducer in the claim 1～6, and this display unit has:

Ultrasonic speaker, signal sound of audio-band is provided from the voice signal that is provided by the sound equipment source for it; And

Projection optical system, its with video-projection in the perspective plane.

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