552164 玖、發明說明 【發明所屬之技術領域】 本發明係關於將空氣等介質加熱而產生壓力波之熱誘 導壓力波產生裝置、喇叭及超音波產生裝置。其技術領域 屬於：距離量測及液面量測等之量測領域、在監視系統上 對人及物體的檢測、汽車及機械人等之檢測障礙物及周遭 物體用的感測器、汽車上乘坐人員的位置及姿勢的感測器 、音響器材（喇叭）、非線性音響元件、參數陣列裝置、微細 裝配及微小物體操縱（利用放射壓以非接觸方式來操縱物體) 、以觸覺顯示器爲代表之虛擬實境等。 【先前技術】 以此種領域之技術而言，已有使壓電材料及固體膜振 動，在空氣中產生超音波之技術。 另一方面，與上述技術不同之先前技術，在日本專利 特開平11-300274號公報上已提出一種熱誘導超音波產生裝 置。藉此，可產生以前所沒有之寬頻超音波，而容易實現 集積化超音波陣列。 【發明內容】 可是，上述之習知熱誘導超音波產生裝置，超音波的 產生效率差，可產生之音波的功率也小，以致於未能合乎 實用。 本發明，有鑒於上述情形，其目的在於提供一種可大 幅提高熱誘導超音波產生效率及產生功率之熱誘導壓力波 產生裝置。 6 552164 本發明，爲了達成上述目的， [1] 熱誘導壓力波產生裝置，係具備：基板、設於該 基板上之絕熱層、及設於該絕熱層上由電氣驅動之發熱體 電極；其特徵在於：使前述發熱體電極的面積變小，並且 使施加於前述發熱體電極之電流形成功率在短時間內集中 之週期性或非週期性的脈衝狀或突波狀，藉此相對單位時 間之平均送入電力，提高發音之單位時間平均功率。 [2] 熱誘導壓力波產生裝置，係具備：基板、設於該 基板上之絕熱層、及設於該絕熱層上由電氣驅動之發熱體 電極；其特徵在於：使前述發熱體電極的面積變小，並且 在前述發熱體電極上連接音響放大器，使所送出之音功率 增加。 [3] 在上述[2]記載之熱誘導壓力波產生裝置中，前述 音響放大器，係與熱誘導超音波的有效放射阻抗匹配之音 響放大器。 [4] 在上述[1]或[2]記載之熱誘導壓力波產生裝置中， 使前述發熱體電極呈摺狀，使前述發熱體電極接觸空氣之 面積變大，而產生強壓力波。 [5] 在上述[1]或[2]記載之熱誘導壓力波產生裝置中， 前述發熱體電極形成於前述基板上之溝槽或孔的內壁上， 使前述發熱體電極接觸空氣之面積變大，而產生強壓力波 [6] 在上述[5]記載之熱誘導壓力波產生裝置中，分割 前述發熱體電極，以與往既定方向前進之進行波同步之方 552164 式驅動分開之電極，藉此產生強壓力波。 [7] 在上述[5]記載之熱誘導壓力波產生裝置中，前述 溝槽或孔，係圓柱形或角柱形溝槽或孔，在該溝槽或孔的 內壁配設複數個發熱體電極，以與往前述圓柱形或角柱形 溝槽或孔的長邊方向前進之波動同步之方式驅動前述複數 個發熱體電極，藉此產生往前述圓柱形或角柱形溝槽或孔 的長邊方向前進之強壓力波。 [8] 在上述[1]或[2]記載之熱誘導壓力波產生裝置中， 將前述發熱體電極以多個微小突起物支撐，藉此使前述基 板與發熱體電極間絕熱。 【實施方式】 以下，詳細說明本發明之實施形態。 第1圖，顯示本發明實施例之熱誘導壓力波產生裝置之 構成圖，第1圖⑷爲其剖面圖，第1圖（b)爲其俯視圖。 在這些圖中，1爲基板，2爲絕熱層，3爲發熱體電極， 4爲發熱體電極3之配線，5爲音響放大器，6爲施加電流於 發熱體電極3之訊號產生器。 以後之說明是以已知如下在熱誘導壓力波產生中成立 的性質爲前提，亦即，所產生之音波的音壓Ρ(ω)與送入之 電力(1(ω)成正比，若在放射面之音響阻抗相等，則單位面 積之送入電力與所產生之音波的音壓Ρ(ω)的比會不拘頻率 大小均相等。 此時，設發熱體電極3的直徑爲d，將q[W/m2]的電力送 入該發熱體電極3時，若在音響放大器5的底部產生之音壓 552164 爲Ρ=α Q[Pa]時，將其縮小爲l/n，並使頻率變爲n倍時，產 生之音壓Ρ’則爲 Ρ, =a qf 因此，若送入之電力保持一定，q’ =n2q，則放射出之 音響功率的總量爲 7Γ d2P’ 2/n2 p c=n2 ( π ά2?2/ ρ c) 變成縮小前的η2倍。 因此，藉由將發熱體電極3的面積微小化，在相同的送 入電力下音響功率會增大。接著，若不是如第2圖（a)所示送 入固定振幅A的電力，而是如第2圖（b)所示將送入電力的時 間變爲全部之Ι/k：倍，並將振幅變爲k倍時，則平均送入電力 沒有改變。可是，因爲在送入電力的瞬間，發音功率會變 爲k2倍，所以，發音之單位時間平均功率爲（l/k)k2=k，變成 k倍。 因此，若對第2圖⑷進行如第2圖（b)之驅動方法，則在 相同之平均送入電力下，發音之單位時間平均功率會變成k 倍。 又，對熱誘導超音波之送入電力q會引起發熱體電極3 表面之溫度變化量TQ，從該溫度變化量％計算發音之音壓 的等價電路如第3圖所示。 將發熱體電極前面之音響阻抗代入阻抗Z，則此時，流 過電路之電流會相當於在發熱體電極表面附近之空氣的粒 子速度，Z的兩端電壓會相當於發音之音壓。 將等價輸出阻抗寫成pC(pc爲空氣之特性阻抗) 552164 則 1/3 blc/^C/wKr )丨与 85 (在 100kHz時）。在此，c爲空 氣中之音速，C爲空氣之單位體積的定容熱容量，K爲空氣 之熱傳導率，r爲比熱比（空氣時，約L4)。例如，若頻率 爲100kHz，丨/3丨与85。 因此，使音響放大器輸入端的直徑爲發熱體電極直徑 的l/m(m=，/5=/"85)(面積比變成/3，相對於發熱體電極之 阻抗Z變爲/3倍。但是，是在該等直徑小於音波之波長的情 況下），則送出之音波的能量變最大。 又，在上述實施例中，在空間、時間上使能量集中時 ，遲早會超出發熱體電極所能容許之電流値及溫度。在此 限制下，若要使發音之音壓再增大，使用如下之發熱體電 極結構即可。 第4圖係顯示本發明實施例之發熱體電極的變形例示意 圖，其中（a)爲鋸齒狀發熱體電極的例子；（b)爲附溝槽狀之 發熱體電極的例子；（c)爲配置在溝槽內之分開之發熱體電 極的例子。 第1發熱體電極，如第4圖（a)所示，在鋸齒狀基板7上形 成絕熱層8，在該絕熱層8上形成鋸齒狀發熱體電極9。在該 鋸齒狀之發熱體電極9上連接有訊號源10。11表示放射出之 音波。 如此，形成鋸齒狀發熱體電極9，在相同之放射面積下 將空氣與鋸齒狀發熱體電極9接觸之面積變爲X倍，藉此發 音之音壓會變爲X倍。但是，此時的條件爲當鋸齒的高度遠 552164 小於發音之音波波長時。 又，在這例子雖以鋸齒狀發熱體電極9來作說明’但若 能形成褶狀，則可以是各種不同之形狀。 第2發熱體電極，如第4圖（b)所示，在附溝槽狀之基板 12的溝槽內壁形成絕熱層13，在該絕熱層13上形成溝槽狀 之發熱體電極14。在該溝槽狀之發熱體電極14上連接有訊 號源15。16表示放射出之音波。 如此之構成與平面之發熱體電極比較起來，也可提高 發音之音壓。 第3發熱體電極，如第4圖（c)及第5圖所示，在附孔狀之 基板17的溝槽內壁形成絕熱層18，在該絕熱層18上形成分 開之溝槽狀發熱體電極19a、19b、19c。在該等分開之溝槽 狀發熱體電極19a、19b、19c上分別連接有訊號源20a、20b 、20c。21表示放射出之音波。 如此之構成與平面之發熱體電極比較起來，也可提高 發音之音壓。 又，該等鋸齒狀發熱體電極之鋸齒高度及溝槽狀發熱 體電極之溝槽高度，若超出發音之音波波長的一半，就算 形成更高之鋸齒及溝槽，效果也會降低，可是，藉由如下 之構成可獲得改善。 在這個實施例中，可用電極圍起一個空間。 如此，如分開之孔狀發熱體電極19a、19b、19c，將發 熱體電極以比波長小之大小來分割，並分別以訊號源20a、 20b、20c獨立驅動，若使其相位與進行波的相位一致，則 11 552164 藉由延長該構造，也可得到與發熱體電極的面積成正比之 強音壓。 第6圖係顯示另一例子之分開的平板狀發熱體電極之構 成圖。 在此例中，在附橫向方孔之基板31的方孔上形成絕熱 層（未圖示），並只在該方孔下面形成分開之平板狀發熱體電 極32a、32b、32c。該等分開之平板狀發熱體電極32a、32b 、32c上連接有訊號源（未圖示）。33表示放射出之音波。 在這個實施例中，如第6圖所示，只有單面有發熱體電 極32a、32b、32c，製作變得更爲簡單。又，基板之間隔與 波長相同時，可給予各個發熱體電極相同的訊號來產生音 波。 第7圖係顯示本發明另一實施例之熱絕緣構成之剖面圖 〇 在這個實施例中，不使用固體膜狀之絕熱層，而是如 第7圖所示在基板41上形成間隔W爲10// m左右之突起物42， 並以該突起物42支撐發熱體電極43。使該發熱體電極43的 厚度在lOnrn以下，並且使發熱體電極43與基板41間絕緣非 常良好，藉此可增加單位消耗電力之發音音壓功率。 又，本發明並不限定於上述實施例，依據本發明之內 容可作各種變形，這些並未排除於本發明的範圍之外。 依據本發明，可大幅提高熱誘導超音波產生裝置之熱 誘導超音波產生效率與最大之發音音壓，不僅能超越習知 音響器材、超音波產生器的性能，強超音波上之新應用也 12 552164 變爲可能。例如，不僅可應用於量測的領域，也可實現可 利用音響器材與強超音波之非線性效果的裝置。 藉此，不僅將習知超音波裝置替換爲更高性能之裝置 ，也可實現應用於參數陣列等非線性聲學元件、放射壓致 動器、觸覺顯示器等新應用之超音波產生裝置。 【圖式簡單說明】 (一）圖式部分 第1圖，係顯示本發明實施例之熱誘導壓力波產生裝置 構成圖。 第2圖，係顯示本發明實施例之發熱體電極的與時間有 關之驅動方法說明圖。 第3圖，係計算本發明熱誘導超音波產生之音壓的等價 電路圖。 第4圖，係顯示本發明實施例之發熱體電極的變形例示 意圖。 第5圖，係顯示於第4圖（c)之第3發熱體電極的立體圖。 第6圖，係顯示本發明實施例之橫向方孔上之分開的平 板狀發熱體電極的構成圖。 第7B，係顯示本發明另一實施例之絕熱構造之剖面圖 〇 (-0¾丨牛代表符號 1 ' 41 基板 2 ' 8、13、18 絕熱層 3 ' 43 發熱體電極 552164 4 發熱體電極之配線 5 音響放大器 6 施加電流於發熱體電極之訊號產生器 7 鋸齒狀基板 9 鋸齒狀發熱體電極 10、 15、20a、20b、20c 訊號源 11、 16、21、33 放射出之音波 12 附溝槽之基板552164. Description of the invention [Technical field to which the invention belongs] The present invention relates to a thermally induced pressure wave generating device, a horn, and an ultrasonic wave generating device that generate pressure waves by heating a medium such as air. Its technical fields belong to the measurement fields such as distance measurement and liquid level measurement, the detection of people and objects on monitoring systems, the detection of obstacles and surrounding objects by automobiles and robots, and sensors for automobiles. Sensors for the position and posture of passengers, audio equipment (horns), non-linear acoustic components, parameter array devices, micro-assembly and manipulation of small objects (manipulating objects in a non-contact manner using radiation pressure), represented by tactile displays Virtual reality, etc. [Previous technology] In the field of this technology, there is a technology that vibrates a piezoelectric material and a solid film to generate an ultrasonic wave in the air. On the other hand, a prior art different from the above-mentioned technology has been proposed in Japanese Patent Laid-Open No. 11-300274 as a heat-induced ultrasonic generation device. As a result, it is possible to generate a wideband ultrasonic wave which is not available before, and it is easy to realize an integrated ultrasonic array. [Summary of the Invention] However, the above-mentioned conventional heat-induced ultrasonic wave generating device has a poor ultrasonic wave generating efficiency, and the power of the ultrasonic wave that can be generated is also too small to be practical. The present invention has been made in view of the above circumstances, and an object thereof is to provide a heat-induced pressure wave generating device that can greatly improve the heat-induced ultrasonic wave generation efficiency and power generation. 6 552164 According to the present invention, in order to achieve the above object, [1] a heat-induced pressure wave generating device includes a substrate, a heat-insulating layer provided on the substrate, and a heat-generating electrode that is electrically driven on the heat-insulating layer; It is characterized in that the area of the heating element electrode is reduced, and the current applied to the heating element electrode is formed into a periodic or non-periodic pulse shape or a surge shape in which the power is concentrated in a short time, so that the unit time is relatively The average power is fed to increase the average power per unit time of pronunciation. [2] A heat-induced pressure wave generating device includes a substrate, a heat-insulating layer provided on the substrate, and a heat-generating electrode that is electrically driven and is provided on the heat-insulating layer; It becomes smaller, and an acoustic amplifier is connected to the heating element electrode, so that the power of the sent sound is increased. [3] In the heat-induced pressure wave generating device described in [2] above, the acoustic amplifier is an acoustic amplifier that matches the effective radiation impedance of a heat-induced ultrasonic wave. [4] In the heat-induced pressure wave generating device described in the above [1] or [2], the heating element electrode is folded, and the area of the heating element electrode in contact with air is increased to generate a strong pressure wave. [5] In the heat-induced pressure wave generating device described in the above [1] or [2], the heating element electrode is formed on an inner wall of a groove or a hole on the substrate, and the area where the heating element electrode is exposed to air It becomes larger and generates a strong pressure wave. [6] In the heat-induced pressure wave generating device described in [5] above, the aforementioned heating element electrode is divided, and the separated electrode is driven by a square-type 552164-type driven synchronous wave that advances in a predetermined direction. This generates strong pressure waves. [7] In the heat-induced pressure wave generating device described in the above [5], the groove or hole is a cylindrical or angular cylindrical groove or hole, and a plurality of heating elements are arranged on an inner wall of the groove or hole. The electrode drives the plurality of heating element electrodes in a synchronous manner with the fluctuations in the direction of the long side of the cylindrical or angular cylindrical groove or hole, thereby generating the long side of the cylindrical or angular cylindrical groove or hole. Strong pressure wave moving forward. [8] In the heat-induced pressure wave generating device according to the above [1] or [2], the heating body electrode is supported by a plurality of minute protrusions, thereby insulating the substrate and the heating body electrode from each other. [Embodiment] Hereinafter, an embodiment of the present invention will be described in detail. Fig. 1 is a structural diagram showing a heat-induced pressure wave generating device according to an embodiment of the present invention. Fig. 1 is a sectional view thereof, and Fig. 1 (b) is a plan view thereof. In these figures, 1 is a substrate, 2 is a thermal insulation layer, 3 is a heating body electrode, 4 is a wiring of the heating body electrode 3, 5 is an acoustic amplifier, and 6 is a signal generator that applies a current to the heating body electrode 3. The following description is based on the premise that it is known to be true in the generation of heat-induced pressure waves, that is, the sound pressure P (ω) of the generated sound wave is proportional to the incoming power (1 (ω). The acoustic impedance of the radiation surface is equal, and the ratio of the input power per unit area to the sound pressure P (ω) of the generated sound wave will be equal regardless of the frequency. At this time, let the diameter of the heating electrode 3 be d, and q When the [W / m2] power is fed into the heating element electrode 3, if the sound pressure 552164 generated at the bottom of the audio amplifier 5 is P = α Q [Pa], it is reduced to 1 / n and the frequency is changed. At n times, the generated sound pressure P ′ is P, = a qf. Therefore, if the input power is kept constant and q ′ = n2q, the total sound power emitted is 7Γ d2P '2 / n2 pc = n2 (πά2? 2 / ρ c) becomes η2 times before reduction. Therefore, by minimizing the area of the heating element electrode 3, the acoustic power will increase under the same input power. Then, if not As shown in FIG. 2 (a), the electric power of a fixed amplitude A is fed, but as shown in FIG. 2 (b), the time of the electric power is changed to 1 / k: times of all, and When the amplitude becomes k times, the average input power does not change. However, since the instantaneous power is input, the sound power becomes k2 times. Therefore, the average power per sound unit is (l / k) k2 = k , It becomes k times. Therefore, if the driving method of Fig. 2 (b) is performed as shown in Fig. 2 (b), the average power per unit time of sound will become k times under the same average power input. The electric power q induced by ultrasonic waves will cause the temperature change amount TQ on the surface of the heating electrode 3, and the equivalent circuit for calculating the sound pressure of the sound from the temperature change% is shown in Figure 3. The sound in front of the heating electrode Impedance is substituted into impedance Z. At this time, the current flowing through the circuit will be equivalent to the particle velocity of air near the surface of the heating element electrode, and the voltage across Z will be equivalent to the sound pressure. Write the equivalent output impedance as pC ( pc is the characteristic impedance of air) 552164 then 1/3 blc / ^ C / wKr) and 85 (at 100kHz). Here, c is the speed of sound in air, C is the constant volume heat capacity per unit volume of air, K is the thermal conductivity of air, and r is the specific heat ratio (in air, about L4). For example, if the frequency is 100kHz, 丨 / 3 丨 and 85. Therefore, the diameter of the input end of the acoustic amplifier is made to be 1 / m (m =, / 5 = / " 85) (the area ratio becomes / 3, and the impedance Z relative to the heating element electrode becomes / 3 times the diameter of the heating element electrode). However, in the case where the diameter is smaller than the wavelength of the sound wave), the energy of the transmitted sound wave becomes the largest. Moreover, in the above-mentioned embodiment, when the energy is concentrated in space and time, sooner or later, the current and temperature allowable by the heating electrode can be exceeded. Under this limitation, to increase the sound pressure of the pronunciation, the following heating electrode structure can be used. FIG. 4 is a schematic diagram showing a modified example of the heating element electrode according to the embodiment of the present invention, in which (a) is an example of a serrated heating element electrode; (b) is an example of a grooved heating element electrode; (c) is An example of a separate heating element electrode arranged in a trench. As shown in FIG. 4 (a), the first heat generating electrode is formed with a heat insulating layer 8 on the zigzag substrate 7, and a zigzag heating electrode 9 is formed on the heat insulating layer 8. A signal source 10 is connected to the zigzag-shaped heating element electrode 9. 11 indicates the emitted sound wave. In this way, the zigzag heating element electrode 9 is formed, and the area where the air contacts the zigzag heating element electrode 9 becomes X times under the same radiation area, so that the sound pressure will be X times. However, the condition at this time is when the height of the sawtooth is 552164 smaller than the wavelength of the sound of the sound. In this example, although the zigzag-shaped heating element electrode 9 is used for description ', various shapes can be used as long as it can be formed into a pleated shape. As shown in FIG. 4 (b), the second heating electrode is formed with a heat insulating layer 13 on the inner wall of the groove of the substrate 12 with a groove, and a grooved heating electrode 14 is formed on the heat insulating layer 13. A signal source 15 is connected to the groove-shaped heating element electrode 14. 16 indicates an emitted sound wave. Such a structure can also increase the sound pressure of the sound when compared with a flat heating electrode. As shown in FIGS. 4 (c) and 5, the third heating electrode is formed with a heat insulating layer 18 on the inner wall of the groove of the substrate 17 with holes, and separate grooves are formed on the heat insulating layer 18 to generate heat. The body electrodes 19a, 19b, and 19c. Signal sources 20a, 20b, and 20c are connected to the separated groove-shaped heating body electrodes 19a, 19b, and 19c, respectively. 21 indicates the emitted sound wave. Such a structure can also increase the sound pressure of the sound when compared with a flat heating electrode. In addition, if the height of the sawtooth heating electrode and the height of the groove of the grooved heating electrode exceed half of the sound wave wavelength of the sound, even if higher sawtooth and groove are formed, the effect will be reduced, but, Improvement can be obtained by the following constitution. In this embodiment, a space can be surrounded by electrodes. In this way, if the hole-shaped heating body electrodes 19a, 19b, 19c are separated, the heating body electrodes are divided by a size smaller than the wavelength, and are separately driven by the signal sources 20a, 20b, 20c. When the phases are consistent, 11 552164 can also obtain a strong sound pressure proportional to the area of the heating element electrode by extending the structure. Fig. 6 is a diagram showing the structure of a separate flat plate-shaped heating element electrode in another example. In this example, a heat insulating layer (not shown) is formed on a square hole of the substrate 31 with a horizontal square hole, and separate flat plate-shaped heating element electrodes 32a, 32b, 32c are formed only under the square hole. A signal source (not shown) is connected to the separated flat plate-shaped heating body electrodes 32a, 32b, and 32c. 33 represents a radiated sound wave. In this embodiment, as shown in Fig. 6, only the heating body electrodes 32a, 32b, and 32c are provided on one side, and the production becomes simpler. When the interval between the substrates and the wavelength are the same, the same signal can be given to each heating element electrode to generate sound waves. Fig. 7 is a cross-sectional view showing the thermal insulation structure of another embodiment of the present invention. In this embodiment, instead of using a solid film-like heat insulation layer, as shown in Fig. 7, a space W is formed on the substrate 41 as The protrusion 42 is about 10 // m, and the heating element electrode 43 is supported by the protrusion 42. The thickness of the heating element electrode 43 is less than 10 nm, and the insulation between the heating element electrode 43 and the substrate 41 is very good, thereby increasing the sound pressure power per unit power consumption. In addition, the present invention is not limited to the above embodiments, and various modifications can be made according to the contents of the present invention, which are not excluded from the scope of the present invention. According to the present invention, the thermally-induced ultrasonic generation efficiency and the maximum sound pressure of the thermally-induced ultrasonic generation device can be greatly improved, which not only surpasses the performance of conventional audio equipment and ultrasonic generators, but also enables new applications on strong ultrasonics. 12 552164 becomes possible. For example, it can be used not only in the field of measurement, but also in devices that make use of the nonlinear effects of audio equipment and strong ultrasound. In this way, not only the conventional ultrasonic device is replaced with a higher-performance device, but also an ultrasonic generation device applied to new applications such as a non-linear acoustic element such as a parameter array, a radiation pressure actuator, and a haptic display. [Brief description of the drawings] (I) Schematic part The first figure is a structural diagram showing a heat-induced pressure wave generating device according to an embodiment of the present invention. Fig. 2 is an explanatory diagram showing a time-dependent driving method of a heating body electrode according to an embodiment of the present invention. Fig. 3 is an equivalent circuit diagram for calculating a sound pressure generated by a heat-induced ultrasonic wave of the present invention. Fig. 4 is a schematic diagram showing a modification example of the heating body electrode according to the embodiment of the present invention. Fig. 5 is a perspective view of a third heating element electrode shown in Fig. 4 (c). Fig. 6 is a structural view showing a flat plate-shaped heating element electrode separated in a horizontal square hole according to an embodiment of the present invention. Section 7B is a cross-sectional view showing a heat-insulating structure of another embodiment of the present invention. (-0¾ 丨 Null symbol 1 '41 Substrate 2' 8, 13, 18 Heat-insulating layer 3 '43 Heat-generating electrode 552164 4 Wiring 5 Acoustic amplifier 6 Signal generator that applies current to the heater electrode 7 Zigzag substrate 9 Zigzag heater electrode 10, 15, 20a, 20b, 20c Signal source 11, 16, 21, 33 Sound wave emitted 12 With groove Slot substrate
14 溝槽狀發熱體電極 17 附孔狀之基板 19a 、 19b 、 19c 31 32a 、 32b 、 32c 42 分開之孔狀發熱體電極 附橫向方孔之基板 分開之平板狀發熱體電極 突起物14 Grooved heating electrode 17 Substrate with holes 19a, 19b, 19c 31 32a, 32b, 32c 42 Separate hole-shaped heating element electrode Substrate with lateral square hole Separate flat-shaped heating element electrode Protrusion
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