P15E-5 P15E5 YYYYYYYYYYYYYYYYYYYYYYYY02 YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY03

No.P15E5.pdf 2001.6.4 PIEZOELECTRIC SOUND COMPONENTS APPLICATION MANUAL Murata Manufacturing Co., Ltd. This is the PDF file of

This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 PIEZOELECTRIC SOUND COMPONENTS APPLICATION MANUAL Murata Manufacturing Co., Ltd. This is the PDF file of catalog No.P15E-5 P15E-5. Introduction Murata is active in R&D of new electronic components, seeking infinite possibility of ceramic materials. Particularly, as a pioneer in the development of piezoelectric ceramics, Murata has met the needs of technical revolution in electronics with original products. Our ceramic resonators (CERALOCK®), ceramic filters (CERAFIL®), piezo buzzers and various ultrasonic transducers have been contributed to the development of electronics. The"Piezoelectric sound components"introduced herein operates on an innovative principle utilizing natural oscillation of piezoelectric ceramics. Today, piezoelectric sound components are used in many ways such as home appliances, OA equipments, audio equipments and telephones etc. And they are applicated widely, for examples, alarms, speakers, telephone ringers, receivers, transmitters and beep sounds etc. This manual is made for customers to use piezoelectric sound components efficiently and with no trouble. It is recommended that the manual be read while referring to the catalog. No.P15E5 P15E5.pdf 2001.6.4 This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 CONTENTS 1 Type of piezoelectric sound components and Oscillating system YYYYYYYYYYYYYYYYYYYYYYYY02 YYYYYYYYYYYYYYYYYYYYYYYY02 1.Type of piezoelectric sound components .02 2.Oscillating system .02 2 Procedures YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY03 YYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYYY03 1.Soldering procedures .03 2.Design procedure .03 3.Drive procedure .04 External drive method .04 Self drive method .05 YYYYY07 YYYYY07 1.Characteristics .07 3 Characteristics and measuring method 2.Measuring Procedure .07 Measurement of resonant frequency and resonant impedance.07 Measurement of sound pressure level (S. P. L.).08 YYYYYYYYYYYYYY09 YYYYYYYYYYYYYY09 1.Voltage and temperature characteristics .09 4 Environmental Characteristics 2.Environmental test .09 1 Type of piezoelectric sound components and Oscillating system 2 Procedures 3 Characteristics and measuring method 4 Environmental Characteristics This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 1 Type of piezoelectric sound components and Oscillating system 1. Type of piezoelectric sound components DRIVING PROCEDURES TYPE STANDARD PARTS SELF DRIVE PIEZOELECTRIC DIAPHRAGM 7BB-27-3R5 7BB-27-3R5 PIEZOELECTRIC SOUNDER 1 EXTERNAL DRIVE PKM22EPT-2001-B0 PKM22EPT-2001-B0 PIEZOELECTRIC BUZZER PIEZOELECTRIC SPEAKER BUILT IN CIRCUIT PKB24SPC-3601-B0 PKB24SPC-3601-B0 VSB35EW-0701B VSB35EW-0701B 2. Oscillating system Basically, sound source of a piezoelectric sound component is a piezoelectric diaphragm. A piezoelectric diaphragm consists of a piezoelectric ceramic plate which have electrodes on both sides and a metal plate (brass or stainless steel etc). A piezoelectric ceramic plate is attached to a metal plate with adhesives. Fig. 2 shows the oscillating system of a piezoelectric diaphragms. Applying D. C. voltage between electrodes of a piezoelectric diaphragm causes mechanical distortion due to the piezoelectric effect. For a disshaped piezoelectric element, the distortion of the piezoelectric element expands in radial direction. And the piezoelectric diaphragm bends toward the direction shown in Fig.2 (a). The metal plate bonded to the piezoelectric element does not expand. Conversely, when the piezoelectric element shrinks, the piezoelectric diaphragm bends in the direction shown in Fig.2 (b). Thus, when AC voltage is applied across electrodes, the bending shown in Fig.2 (a) and Fig.2 (b) is repeated as shown in Fig.2 (c), producing sound waves in the air. ELECTRODE PIEZOELECTRIC CERAMICS PIEZOELECTRIC ELEMENT ELECTRODE PIEZOELECTRIC CERAMICS METAL PLATE Fig. 1 Structure of piezoelectric diaphragm (a) EXTENDED STATE (c) A. C. VOLTAGE APPLIED (b) SHRINKED STATE Fig. 2 Oscillation system 2 PIEZOELECTRIC DIAPHRAGM This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 2 Procedures 1. Soldering procedures A lead wire is needed to apply voltage to the piezoelectric diaphragm. When using a soldering iron, the optimum temperature for soldering a lead wire to a metal plate is 300 for a few seconds and the same temperature for the ceramic silver electrode for 0.5 second or less. The lead wire should be as fine as possible, as it works as a load restricting oscillation of the piezoelectric diaphragm. (Example: AWG32 AWG32) 2 2. Design procedure In general, man's audible frequency range is about 20 Hz to 20kHz. Frequency range of 2kHz to 4kHz are most easily heard. For this reason, most piezoelectric sound components are used in this frequency range, and the resonant frequency (f0) is generally selected in the same range too. As shown in Fig. 3, the resonant frequency depends on methods used to support the piezoelectric diaphragm. If piezoelectric diaphragms are of the same, shape, their values will become smaller in the order of (a), (b) and (c). In general, the piezoelectric diaphragm is installed in a cavity to produce high sound pressure (Fig. 4). The resonant frequency (fcav) of the cavity in Fig. 4 is obtained from Formula (1) (Helmholtz's Formula). Since the piezoelectric diaphragm and cavity have proper resonant frequencies, (f0) and (fcav) respectively, sound pressure in specific frequencies can be increased and a specific band width can be provided by controlling the both positions. (a) Node support f0 = 0.412t r2 E (1 2) (b) Edge support f0 = 0.233t r2 E (1 2) (c) Central support f0 = f0 : Resonant frequency t : Thickness r : a radius of a metal plate 0.172t r2 E (1 2) E : Young's modulus : Density : Poisson's ratio Fig. 3 Supporting method 2a fcav = C 2 a 2 C = V (R+1.3a) 2 fcav : Resonant freq. of a cavity (Hz) c : the speed of sound (cm/sec) a : radius of sound emitting hole (cm) h V R d 4a 2 . 1 d 2h (R+1.3a) d : diameter of a supporting rim (cm) h : depth of a cavity (cm) R: wall thickness of a cavity (cm) Fig. 4 Sectional view of a cavity 3 This is the PDF file of catalog No.P15E-5 P15E-5. 2 No.P15E5 P15E5.pdf 2001.6.4 Procedures 3. Drive procedure Drive procedures for piezoelectric sound components include (a) external drive method and (b) self drive method as shown in Fig. 5. 2 (a) EXTERNAL DRIVE METHOD EXTERNAL DRIVE CIRCUIT External drive method This method produces sound by driving the piezoelectric diaphragm with electric signals supplied from an external oscillating circuit such as a multivibrator. Using this method, the piezoelectric buzzer can work as a speaker. In this method, a mechanical oscillation Qm of the piezoelectric diaphragm is damped properly to provide a wider frequency band of the sound pressure. This is applied to a switching sounds of home electric appliances, key-in sounds of OA equipments, alarm sounds of digital watches and the multiple sounds like those used in electronic games. This method is also applied to the ringers, transmitters, receivers of telephone sets, tweeters, card radios and speakers of crystal TV's. Fig. 6 shows the examples of the circuit to which the external drive method is applied. (i) represents a circuit in which output signals of the unstable multivibrator are boosted through the coil and transistors. (ii) represents a circuit using 2 NAND gates, which is oscillated or stopped by ON / OFF operations of the input signal. (iii) and (iv) represent example of the piezoelectric diaphragm connected to telephone tone ringer IC. EDGE SUPPORT (b) SELF DRIVE METHOD SELF DRIVE CIRCUIT NODE SUPPORT Fig. 5 Drive procedure 0.47µF 2.2k +V 510 20k 20k 510 55mH 8 1 2 OUT 7 1-2k 0.01µF 0.01µF 1k PIEZO RINGER 6 10µF 4 ROSC TCM1506A TCM1506A (T.I) iii i TA31002PTOSHIBA TA31002PTOSHIBA 1µF 1M 0.001µF +V 1-2k 2k 1 2 1k 120k 16.5k 8 7 15µF INPUT SIGNAL 3 6 4 1k 5 3300pF 27V 0.47µF ii iv Fig. 6 Example's of the external drive circuit 4 PIEZO RINGER 180k This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 2 Procedures Notice (handling) in using external drive circuit 1) Electric charges accumulated in the piezoelectric diaphragm due to thermal and mechanical shock may cause high voltage which may destroy LSI. Use the method using a Zener diode as shown in Fig. 7 to prevent this. 2) Applying D. C. voltage to the piezoelectric diaphragm in the environment of high humidity causes Ag migration. Therefore, design a circuit which does not require D. C. voltage be applied for a long time. 3) Consider the following points in connecting a piezo ringer and tone ringer IC. i) For external capacitors and resisters; especially, when the ringing frequency is changed by adjusting variable resister, tone may be distorted. ii) Ringer ICs; ringer ICs are produced by many manufactures have different characteristics. When using a ringer IC, consult us or its manufacturer for operating procedures. iii) If tone is distorted as discribed in Fig. 8 (a), place a resister in series to vary resistance as described in (b) and select a resistance with which the distortion can be eliminated. The recommended resistance is in a range between lkohms to 2kohms. Alternatively, it is recommended to place a diode in parallel with the piezo ringer. BUZZER LSI Fig. 7 Protect circuit 2 a b R IC IC C c R IC Fig. 8 Circuits for piezo ringer Self drive method Fig. 9 shows a typical application of the self drive method. The piezoelectric diaphragm provided with feedback electrode shown in Fig.9 (i) is involved in the closed loop of a hartley types oscillation circuit. When the frequency is closed to the resonant frequency, the circuit satisfies oscillating conditions, and the piezoelectric diaphragm is driven with the oscillating frequency. Fig. 9 (ii) shows a simple oscillating circuit consisting of one transistor and three resistors. In general, the node support shown in Fig. 3 (a) is popular in the self drive method. Proper resonance of the piezoelectric diaphragm by the node support provides stable oscillation with high mechanical Qm of vibration but also a single high pressure tone. Basic oscillating conditions of this circuit are shown below. a. Phase difference between o and f shown in Fig. 9 must be 180 degrees. b. The following conditions must be satisfied: R2+hie f / o U hfeR3 where; hie: Input impedance of transistor hfe: Current amplification c. Set R1 so that the D. C. bias point of transistor, VCE is half of supply voltage. d. Adjust R2 so that spurious oscillation is not applied to oscillating waves. ( i ) PIEZOELECTRlC DIAPHRAGM FOR SELF DRIVE ( ii ) SELF DRIVE CIRCUIT +V INPUT ELECTRODE R1 R3 M F o R2 G METAL PLATE (GROUND) i f FEEDBACK ELECTRODE Fin. 9 Self drive circuit 5 This is the PDF file of catalog No.P15E-5 P15E-5. 2 2 Procedures Notice (handling) in using self drive method 1) When the piezoelectric buzzer is set to produce intermittent sounds, sound may be heard continuously even when the self drive circuit is turned ON / OFF at the"X"point shown in Fig. 9. It is because of the failure of turning off the feedback voltage. 2) Builed up a circuit of the piezoelectric sounder exactly as per the recommended circuit shown in the catalog. hfe of the transistor and circuit constants are designed to ensure stable oscillation of the piezoelectric sounder. 3) Design switching which ensures direct power switching. 4) The self drive circuit is already contained in the piezoelectric buzzer. So there is no need to prepare an another circuit to drive the piezoelectric buzzer. 5) Rated voltage (3.0 to 20Vdc) must be kept. Products which can operate with voltage higher than 20Vdc are also available. 6) Do not place resistors in series with the power source, as this may cause abnormal oscillation. If a resistor is essential to adjust sound pressure, place a capacitor (about 1µF) in parallel with the piezo buzzer. +VDD PIEZO BUZZER 7) Do not close the sound emmitting hole on the front side of casing. 8) Carefully install the piezo buzzer so that no obstacle is placed within 15mm from the sound release hole on the front side of the casing. 6 No.P15E5 P15E5.pdf 2001.6.4 This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 3 Characteristics and measuring method 1. Characteristics TYPE PIEZOELECTRIC DIAPHRAGM RESONANT FREQUENCY RESONANT IMPEDANCE CAPACITANCE SOUND PRESSURE LEVEL PIEZOELECTRIC SOUNDER (EXTERNAL DRIVE) OSCILLATING CURRENT FREQUENCY CONSUMPTION INPUT VOLTAGE OPERATING VOLTAGE PIEZOELECTRIC SOUNDER (SELF DRIVE) PIEZOELECTRIC BUZZER PIEZOELECTRIC SPEAKER REMARKS 3 COMMON CONDITIONS: OPERATING TEMP. RANGE / STORAGE TEMP. RANGE MEASUREMENT INSTRUMENTS: LCR METER (CAPACITANCE) / FREQ. COUNTER (OSCILLATING FREQ.) MULTI METER (CURRENT CONSUMPTION) 2. Measuring Procedure Measurement of resonant frequency and resonant impedance MEASURING TERMINAL When the piezoelectric diaphragm oscillates freely in air, the node does not move as shown in Fig. 10. With this point held with a measuring terminal, the resonant frequency (f0) and resonant impedance (R0) are measured in the constant-current circuit. Measuring procedure 1) Connect the switch to side"a", and adjust frequency of the oscillator to read the frequency and the voltage when the voltmeter indicates a minimum value. 2) Then connect the switch to side"b", and vary the variable resistor to have the same voltage as in 1). Then, read the value of the resistor. 3) The resonant frequency (f0) can be obtained from 1) and the resonant impedance (R0) from 2). : Actual measurement are performed using a measuring unit in accordance with the above principle. NODE SUPPORTING METHOD Fig. 10 Measurement of piezoelectric diaphragm OSCILLATOR (1Vrms max.) VOLTMETER R1 (10k AROUND) FREQUENCY COUNTER a b SWICTH VARIABLE RESISTER PIEZOELECTRIC DIAPHRAGM Fig. 11 Measurement set up of resonant freq. and resonant impedance 7 This is the PDF file of catalog No.P15E-5 P15E-5. 3 No.P15E5 P15E5.pdf 2001.6.4 Characteristics and measuring method Measurement of sound pressure level (S. P. L.) The sound pressure level is measured with a sound pressure level meter as shown in Fig. 12 (Fig. 12 shows an example of the self drive piezoelectric sounder). : The relation between sound pressure level and distance, between sound pressure level and voltage can be expressed with Formula (2). The value of the sound pressure level under different operating conditions can be easily calculated using values specified in the catalog. S. P. L.(dB) [under actual operating conditions] = S. P. L.(dB) [value specified in catalog] -20 log A/B(dB) .(2) 3 In case of relation with distance: A; Actual distance B; Distance specified in catalog In case of relation with voltage: A; Voltage specified in catalog B; Actual operating voltage 8 FREQUENCY COUNTER PIEZOELECTRIC SOUNDER (SELF DRIVE) A OSCILLATION CIRCUIT MEASURING DISTANCE SOUND LEVEL Fig. 12 Measurement set up of S. P. L. PRESSURE METER This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 4 Environmental Characteristics Various environmental changes such as change in room temperature and atmosphere and vibration should be considered at storage instllation and actual operation of the piezoelectric buzzer. Typical voltage and temperature characteristics and environmental tests are shown using the piezoelectric sounder PKM24SP3805 PKM24SP3805 as an example. 1. Voltage and temperature characteristics DISTANCE: 10cm VOLTAGE: 12Vdc DISTANCE: 10cm 100 SOUND PRESSURE (dB) 100 SOUND PRESSURE (dB) 90 5 4 90 5 OSCILLATING FREQUENCY 4 (kHz) OSCILLATING FREQUENCY 4 (kHz) 3 3 CONSUMPTION CURRENT 15 (mA) CONSUMPTION CURRENT 15 (mA) 10 10 5 5 3 5 9 12 15 20 -20 VOLTAGE (Vdc) 0 20 40 70 TEMPERATURE () Fig. 13 Voltage characteristics Fig. 14 Temperature characteristics 2. Environmental test No ITEM CONDITION 1 High temperature +85±2, 240Hrs 2 Low temperature -40±2, 240Hrs 3 Humidity +60±2, R.H. 90-95, 240Hrs 4 Temperature cycle Following cycle 5times; -40±2(30min.) +20(15min.) +85±2(30min.) +20(15min.) DEVIATIONS 5 Vibration Shock Oscillating freq. : Initial value ±10 Consumption current : Initial value ±10 10 to 55Hz (1 cycle, 1 min. ) Amplitude 1.5 mm 2 Hrs for each three mutually perpendicular directions 6 S. P. L. : Initial value ±10dB +100G sine wave 3 times for each three mutually perpendicular direction After following test, samples should be left at natural condition (Temp.; 25°C) for more than 4 hours. 9 This is the PDF file of catalog No.P15E-5 P15E-5. No.P15E5 P15E5.pdf 2001.6.4 Note: 1. Export Control For customers outside Japan Murata products should not be used or sold for use in the development, production, stockpiling or utilization of any conventional weapons or mass-destructive weapons (nuclear weapons, chemical or biological weapons, or missiles), or any other weapons. For customers in Japan For products which are controlled items subject to the "Foreign Exchange and Foreign Trade Law" of Japan, the export license specified by the law is required for export. < < > > 2. Please contact our sales representatives or product engineers before using our products listed in this catalog for the applications listed below which require especially high reliability for the prevention of defects which might directly cause damage to the third party's life, body or property, or when intending to use one of our products for other applications than specified in this catalog. q Aircraft equipment w Aerospace equipment e Undersea equipment r Power plant equipment t Medical equipment y Transportation equipment (vehicles, trains, ships, etc.) u Traffic signal equipment i Disaster prevention / crime prevention equipment o Data-processing equipment !0 Application of similar complexity and/or reliability requirements to the applications listed in the above 3. Product specifications in this catalog are as of May 2001. They are subject to change or our products in it may be discontinued without advance notice. Please check with our sales representatives or product engineers before your ordering. If there are any questions, please contact our sales representatives or product engineers. 4. The parts numbers and specifications listed in this catalog are for information only. You are requested to approve our product specification or to transact the approval sheet for product specification, before your ordering. 5. Please note that unless otherwise specified, we shall assume no responsibility whatsoever for any conflict or dispute that may occur in connection with the effect of our and/or third party's intellectual property rights and other related rights in consideration of your using our products and/or information described or contained in our catalogs. In this connection, no representation shall be made to the effect that any third parties are authorized to use the rights mentioned above under licenses without our consent. 6. None of ozone depleting substances (ODS) under the Montreal Protocol is used in manufacturing process of us. http://www.murata.co.jp/products/ Head Office 2-26-10, Tenjin Nagaokakyo-shi, Kyoto 617-8555, Japan Phone:81-75-951-9111 Cat. No. P15E-5 P15E-5 International Division 3-29-12, Shibuya, Shibuya-ku, Tokyo 150-0002, Japan Phone:81-3-5469-6123 Fax:81-3-5469-6155 E-mail:intl@murata.co.jp