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How to Test Piezoelectric Buzzers for Lamps

The buzzer is a kind of integrated structure of electronic sounders, using DC voltage power supply, widely used in various electronic products as a sounding device, the piezoelectric buzzer is mainly composed of a multi-harmonic oscillator, piezoelectric buzzer, impedance matching device and resonance box, shell, etc. It is widely used in life, emitting high decibel sound to play a warning role, and is also widely used in lamps as police signals.

 

Piezoelectric buzzers are also used in the luminaire industry. The buzzer can be installed in the luminaire and used in combination with the LED light-emitting board. The luminaire is equipped with a 3.7V battery pack to supply power, and a 12V voltage is an output to the buzzer and light-emitting board through the driver control board to form an acoustic and optical alarm signal light. However, during the use of the lamps, they are often affected by vibration, drops, aging after a long period of time, resulting in abnormal phenomena such as the buzzer not ringing and the sound intensity becoming smaller, which eventually leads to the failure of the lamps, thus losing its role as a sound warning.

The existing test standards for piezoelectric buzzers only test the performance of the buzzer itself but do not test the suitability of the piezoelectric buzzer for use in lamps and lanterns, so there are cases where even though the piezoelectric buzzer passes the standard test, problems occur when it is used in lamps and lanterns.

Therefore, it is necessary to provide a testing method for piezoelectric buzzers for lamps and lanterns, which can quickly detect defects in the intrinsic and process of piezoelectric buzzers in a short period of time, provide good and qualified accessories for the lamps and lanterns used, and improve the overall reliability of the lamps and lanterns.

The correct test method for piezoelectric buzzer for lamps, comprising the steps of testing whether the appearance quality of the sample is normal if otherwise, the test is over. Testing whether the working performance of the sample under the preset lower test temperature condition meets the requirements if otherwise, the test is over.

Testing whether the working performance of the sample under the preset upper test temperature condition meets the requirements, if otherwise, the test is over. Testing if the durability of the sample meets the requirements, if not the test is over. Wherein said step of testing the durability of the sample specifically comprises the following steps.

Placing the sample under the preset temperature conditions, inputting a typical operating voltage to continuously work for a preset continuous operating time, cycling for a preset number of cycles with a preset continuous operating time and a preset stopping time after a pause.

At the end of the preset number of cycles, returning to room temperature, and measuring the operating steady current and acoustic stability of the sample when inputting a typical voltage, respectively. After the end of the preset number of cycles, the sample is returned to normal temperature, and the working steady current and the sound intensity of the sample are measured when the typical voltage is input; it is judged whether the working steady current and the sound intensity of the sample meet the requirements, otherwise, the test is finished.

In one embodiment, in said step of testing the durability of the sample, said preset high temperature is 55 °C, said preset continuous operating duration is 23 hours, said preset stopping duration is I hours, and said a preset number of cycles is 7 times.

In one of the embodiments, said testing method further comprises the step of testing whether the heat generation of the heat-generating device within the sample conforms to the corresponding rated temperature value, said step of testing the heat generation of the heat-generating device within the sample specifically comprising the steps of opening the upper and lower shells of the sample, laying a thermocouple on each of the surfaces of the internal heat-generating device, and then re-encapsulating the same; placing the sample in a windless environment, and respectively inputting The lower working voltage, typical working voltage, and upper working voltage are input respectively. Until the device reaches thermal equilibrium and then the surface temperature of each device is recorded; to judge whether the surface temperature of the heat-generating device meets the corresponding rated temperature value, if not, the next step is tested.

In one of the embodiments, said test method further includes the step of testing whether the drop resistance of the sample meets the requirements, said step of testing the drop resistance of the sample further includes the following steps: placing the sample at a predetermined height of not less than I meter at room temperature. And dropping it to the ground with multiple landing force directions for not less than 4 predetermined number of drops; after each drop, observing whether the upper and lower shells of the sample are combined After each drop, observe whether the combination of the upper and lower shells of the sample is tight, whether the sample’s internal noise is not loose, and check whether the function of the sample is normal by powering it on, otherwise the test is finished.

In one of the embodiments, the step of testing the working performance of the sample at the preset lower test temperature comprises the following steps: placing the sample at the preset lower test temperature of -25°C for 2 hours, then inputting the lower working voltage, typical working voltage, and upper working voltage respectively, observing whether the sound intensity is normal and recording the input current value at each of the three voltage points when the working is stable. Continue to work continuously under each voltage point for 2 hours, and observe whether the working process is normal. After restoring to normal temperature, measure the working stable current and the sound intensity value of the sample when inputting typical voltage respectively, if otherwise the test is finished.

In one of the embodiments, the step of testing the working performance of the sample at the preset upper test temperature comprises the following steps: after the sample is placed at the preset upper test temperature of 55°C for 2 hours, the lower working voltage, typical working voltage, and upper working voltage are input respectively. And observe whether the sound intensity is normal and record the input current value when the three voltage points are working stably. Continue to work continuously under each voltage point for 2 hours and observe whether the working process is normal. After restoring to normal temperature, measure the working stable current and the sound intensity value of the sample when inputting typical voltage respectively, if otherwise the test is finished.

In one of the embodiments, said test method further comprises the step of testing whether the performance of the sample under preset damp-heat conditions meets the requirements, said step of testing the performance of the sample under preset damp-heat conditions specifically includes the following steps: placing the sample in a temperature chamber, setting the preset temperature of the chamber 37°C, 43°C, preset humidity 90%, 96% RH and preset duration of 48 hours The preset duration is 48 hours. 2 hours before the end of the preset duration, the samples were checked for proper function. After restoration to room temperature, the operating steady current and sound intensity values of the sample at typical voltage input are measured separately to see if they meet the requirements. Otherwise, the test is finished.

In one of the embodiments, said test method further comprises the step of testing whether the electrical parameters of the sample meet the requirements of the luminaire design for use, said step of testing the electrical parameters of the sample further comprising the steps of using a DC voltage regulator to input a lower operating voltage, a typical operating voltage and an upper operating voltage to the sample respectively, and measuring the maximum input current when the sample is working stably. Determine whether the maximum input current when the sample is working steadily is in accordance with the design current range of the luminaire, if otherwise the test is finished.

The durability test simulates the continuous work of the sample for a relatively long time and accelerates the aging of the device in order to quickly verify the service life of the sample, thus enabling a good match between the service life of the luminaire and the piezoelectric buzzer, making the design service life of the luminaire itself match the simulated service life of the piezoelectric buzzer, and providing good and qualified buzzers for the luminaire used.