A near-field alarm sound level measuring instrument

Abstract

This utility model discloses a near-field alarm sound level measuring instrument, including a housing. The front of the housing has control buttons and a display screen. A high-sound-pressure microphone is fixedly connected to the upper end of the housing. The high-sound-pressure microphone is a pre-polarized condenser microphone core with a built-in stainless steel explosion-proof mesh. A circuit board is located inside the housing. The installation position of the control buttons corresponds to the contacts on the circuit board. The display screen and the high-sound-pressure microphone are electrically connected to the circuit board via wires. A laser positioner is installed at the upper end of the housing. This utility model has the advantages of accurate measurement, high efficiency and convenience, high reliability, and strong purposefulness, thus meeting the actual needs of accurate near-field sound level measurement for alarm devices such as fire alarms and industrial buzzers. Furthermore, the protective cover protects the high-sound-pressure microphone when not in use.

Description

Technical Field

[0001] This utility model relates to the field of sound level meter technology, and in particular to a near-field alarm sound level measuring instrument. Background Technology

[0002] In fields such as fire safety and industrial production, alarm devices such as fire alarms and industrial buzzers are key equipment for ensuring personnel safety and providing timely warnings of risks. Whether the sound pressure level of their alarm sounds meets the standards directly affects the warning effect. To ensure the normal operation of these alarm devices, it is necessary to accurately measure their sound pressure level at close range. However, currently widely used sound level meters have many shortcomings in this specific measurement scenario and cannot meet actual needs.

[0003] Existing sound level meters are primarily designed for environmental or industrial noise, which are mostly steady-state or slowly changing sound sources, with a typical upper limit of 94-114 dB. However, alarm devices such as fire alarms and industrial buzzers often have sound pressure levels exceeding 120 dB, and some even reaching over 130 dB, when operating at close range, far exceeding the measurement range of ordinary sound level meters. In such cases, the microphone diaphragm of ordinary sound level meters is easily damaged due to its inability to withstand high sound pressure levels, and the data acquisition circuitry may also experience saturation distortion, resulting in the inability to accurately read the true sound pressure level data of the alarm sound, making it difficult to determine whether the alarm device meets the prescribed sound pressure level standard.

[0004] From a signal response perspective, the frequency weighting (such as A-weighting) and time weighting (fast / slow) networks of traditional sound level meters are designed based on conventional steady-state sound sources, and their ability to capture pulse-type alarm sounds is significantly flawed. Alarm sounds are typical pulse signals, characterized by strong transients and prominent peaks. However, traditional sound level meters have slow response speeds and insufficient peak holding capabilities, making it impossible to record the instantaneous peak sound pressure level (PeakSPL) of the alarm sound in a timely and accurate manner. They can only obtain average sound pressure level data over a period of time, which is seriously inconsistent with the core requirement of instantaneous peak data in alarm device sound level measurement, resulting in measurement results lacking practical reference value.

[0005] In real-world applications, industrial environments are often noisy, with background noise from various operating equipment, and some locations may have multiple alarm devices installed simultaneously. Ordinary sound level meters lack effective positioning assistance, making it difficult for operators to quickly and accurately align the measuring device with the sound output port of a specific alarm. This not only fails to guarantee consistency in measurement distance and angle but also makes them susceptible to interference from other surrounding sound sources, leading to misjudgments or missed detections. Consequently, efficient batch testing of multiple alarm devices becomes impossible, impacting equipment maintenance efficiency and the timeliness of safety assurance.

[0006] Therefore, it is necessary to design a near-field alarm sound level measuring instrument to solve the above problems. Utility Model Content

[0007] The purpose of this invention is to address the shortcomings of existing technologies by proposing a near-field alarm sound level measuring instrument. This invention has the advantages of accurate measurement, high efficiency and convenience, high reliability and strong purposefulness, thereby meeting the actual needs of accurate near-field sound level measurement for alarm devices such as fire alarms and industrial buzzers. Furthermore, the protective cover can protect the high sound pressure microphone when not in use.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A near-field alarm sound level measuring instrument includes a housing. The front of the housing has control buttons and a display screen. A high sound pressure level (HSL) microphone is fixedly connected to the upper end of the housing. The HPL microphone is a pre-polarized condenser microphone core with a built-in stainless steel explosion-proof mesh. A circuit board is provided inside the housing. The installation position of the control buttons corresponds to the contacts on the circuit board. The display screen and the HPL microphone are electrically connected to the circuit board via wires. A laser locator is installed at the upper end of the housing.

[0010] Preferably, the circuit board is provided with a high dynamic range acquisition circuit and a signal processing unit, wherein the high dynamic range acquisition circuit includes a preamplifier and an analog-to-digital converter.

[0011] Preferably, the left and right sides of the housing are provided with multiple anti-slip grooves, and the multiple anti-slip grooves are all inclined.

[0012] Preferably, a tripod interface is provided on the rear side of the housing.

[0013] Preferably, a connecting ring is fixedly connected to the upper end of the housing, a protective cover is provided at the upper end of the connecting ring, an annular block is fixedly connected to the inner wall of the protective cover, and slots are provided on both the left and right sides of the annular block. Rectangular cavities are symmetrically provided inside the connecting ring, and a rotating shaft is rotatably connected to the front and rear inner walls of the rectangular cavities. A vertical rod is fixedly connected to the rotating shaft, and a protrusion is fixedly connected to the upper end of the vertical rod. Openings are provided on adjacent sides of the two rectangular cavities, and the two protrusions penetrate the openings. The vertical rod is elastically connected to the inner wall of the corresponding rectangular cavity by a spring.

[0014] Preferably, each of the two rectangular cavities has a strip channel on its opposite side, and each of the two vertical rods has a pressure rod rotatably connected to its opposite side, with each pressure rod extending through the corresponding strip channel to the outside.

[0015] Compared with existing technologies, the advantages of this device are:

[0016] 1. Compared with existing technologies, this device adopts a high sound pressure level resistant microphone with a pre-polarized condenser microphone core and a built-in stainless steel explosion-proof mesh, and is equipped with a high dynamic range acquisition circuit that includes a switchable gain preamplifier and a high-precision analog-to-digital converter. This increases the upper limit of measurement to cover a high sound pressure level of more than 130dB in the near field of the alarm, effectively avoiding the microphone damage and data saturation distortion problems caused by the insufficient measurement range of ordinary sound level meters, and realizing accurate acquisition of the true peak sound pressure level of the alarm sound.

[0017] 2. Compared with existing technologies, this device integrates a laser positioner at the top of the housing, along with a tripod interface on the rear of the housing and anti-slip grooves on the left and right sides. This solves the problems of traditional sound level meters being difficult to position and susceptible to interference in noisy environments or environments with multiple alarms. It can quickly and accurately align with the sound hole of the alarm under test, ensuring the consistency of measurement distance and angle. Furthermore, the anti-slip grip and stable support structure improve the ease of operation and the stability of long-term measurement, significantly reducing the false negative rate and operator fatigue.

[0018] 3. Compared with existing technologies, the device provides easily detachable protection for the high sound pressure level microphone through a connecting ring, protective cover, ring block with slot, and locking structure containing protrusions, springs, and pressure rods at the upper end of the housing. When idle or in harsh environments, the protective cover can be quickly installed to prevent the microphone from being damaged by dust or airflow impact; during measurement, it can be disassembled by pressing the pressure rod. This not only makes up for the lack of dedicated microphone protection in ordinary sound level meters, but also ensures convenience during measurement and extends the service life of core components. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the structure of a near-field alarm sound level measuring instrument proposed in this utility model;

[0020] Figure 2 for Figure 1 A schematic diagram of the rear structure;

[0021] Figure 3 This is a schematic diagram of the structure of a protective cover for a near-field alarm sound level measuring instrument proposed in this utility model;

[0022] Figure 4 for Figure 1 A magnified structural diagram of point A in the middle.

[0023] In the diagram: 1. Housing, 2. Control buttons, 3. Anti-slip grooves, 4. Display screen, 5. Laser positioner, 6. High sound pressure level microphone, 7. Tripod interface, 8. Protective cover, 9. Connecting ring, 10. Ring block, 11. Slot, 12. Protrusion, 13. Vertical rod, 14. Rotating shaft, 15. Spring, 16. Pressure rod, 17. Rectangular cavity. Detailed Implementation

[0024] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0025] Reference Figures 1-4 A near-field alarm sound level measuring instrument includes a housing 1. Multiple anti-slip grooves 3 are provided on both the left and right sides of the housing 1, and these grooves 3 are inclined to ensure stability when held by the hand. A tripod interface 7 is provided on the rear side of the housing 1, allowing the measuring instrument to be connected to the tripod interface 7 for stable measurement over a long period. Control buttons 2 and a display screen 4 are provided on the front side of the housing 1. A high sound pressure level (SPL) resistant microphone 6 is fixedly connected to the upper end of the housing 1. The SPL resistant microphone 6 is a pre-polarized condenser microphone core with a built-in stainless steel explosion-proof mesh to prevent airflow from damaging the diaphragm. A circuit board is provided inside the housing 1, and the installation position of the control buttons 2 corresponds to the contacts on the circuit board. The display screen 4 and the SPL resistant microphone 6 are electrically connected to the circuit board via wires. A laser locator 5 is installed on the upper end of the housing 1.

[0026] The circuit board includes a high dynamic range acquisition circuit and a signal processing unit. The high dynamic range acquisition circuit includes a preamplifier and an analog-to-digital converter. The preamplifier features low noise and low distortion operation amplifier characteristics and provides switchable gain (high / low gain range). The low gain range is dedicated to high sound pressure level measurements above 100dB. The analog-to-digital converter is a 24-bit high-precision ADC with a maximum sampling rate of 96kHz, ensuring distortion-free acquisition of high-frequency pulse signals. The signal processing unit includes a processor, a pulse peak detection algorithm, and automatic range switching. An indicator light is located on the front of the housing 1. The display screen 4, indicator lights, and control buttons 2 constitute the human-machine interface. The control buttons 2 include a "peak hold" button and a "range" button. The indicator light is a dual-color LED, with green indicating measurement in progress and red indicating peak hold has been triggered. The laser positioner 5 emits a red laser dot to accurately align with the sound hole of the alarm under test, ensuring the repeatability of the measurement distance and angle.

[0027] The upper end of the housing 1 is fixedly connected to a connecting ring 9, and the upper end of the connecting ring 9 is provided with a protective cover 8. The inner wall of the protective cover 8 is fixedly connected to an annular block 10, and the left and right sides of the annular block 10 are provided with slots 11. The connecting ring 9 is symmetrically provided with rectangular cavities 17, and the front and rear inner walls of the rectangular cavity 17 are rotatably connected to a rotating shaft 14. A vertical rod 13 is fixedly connected to the rotating shaft 14, and the connection position between the rotating shaft 14 and the vertical rod 13 is at the center of the vertical rod 13. The upper end of the vertical rod 13 is fixedly connected to a protrusion 12, and the two protrusions 12 are adjacent to each other. The sides are inclined, and during the insertion of the protective cover 8, the two protrusions 12 rotate in opposite directions. When the protrusions 12 are aligned with the slots 11, the protrusions 12 will be inserted into the slots 11. The adjacent sides of the two rectangular cavities 17 are provided with openings, and the two protrusions 12 pass through the openings. The vertical rod 13 is elastically connected to the inner wall of the corresponding rectangular cavity 17 by the spring 15. The opposite sides of the two rectangular cavities 17 are provided with strip channels. The opposite sides of the two vertical rods 13 are rotatably connected with pressure rods 16. The two pressure rods 16 extend to the outside through the corresponding strip channels.

[0028] It is worth mentioning that the laser locator 5 in this utility model can be replaced by a physical aiming scope. In addition to the digital display on the screen, an analog bar graph display can be added to more intuitively observe the changing trend of the sound pressure level. A Bluetooth or Wi-Fi module can be added to wirelessly transmit the peak data to a mobile phone or a background management system to achieve digital recording and traceability.

[0029] The functional principle of this utility model can be explained through the following operation: Before use, press the power switch to start the device. After the circuit board is powered on and initialized, the display screen 4 lights up and enters the default "high sound pressure measurement mode". The laser positioner 5 is simultaneously in a standby state. The measuring personnel can use the anti-slip grooves 3 on the left and right sides of the housing 1 to hold the device stably. If long-term or high-precision measurement is required, the tripod can be connected and fixed to the tripod interface 7 on the rear side of the housing 1 to ensure the stability of the device posture. If the equipment is idle, or if there is a lot of dust or airflow interference on site, the protective cover 8 can be connected to the connecting ring 9 at the upper end of the housing 1 via the annular block 10. At this time, the vertical rod 13 in the rectangular cavity 17 of the connecting ring 9 will be driven by the spring force of the spring 15 to drive the protrusion 12 into the slot 11 of the annular block 10, so that the protective cover 8 can seal and protect the high sound pressure microphone 6 at the upper end. Before the measurement begins, simply press the pressure rods 16 on both sides of the housing 1 that extend to the outside. The pressure rods 16 will drive the vertical rod 13 to rotate around the pivot 14 and compress the spring 15, so that the protrusion 12 will disengage from the slot 11. Then the protective cover 8 can be removed to expose the high sound pressure microphone 6 for measurement.

[0030] During measurement, first activate the laser locator 5, precisely aligning the laser point with the sound hole of the alarm under test. Adjust the distance between the device and the alarm to the standard measurement range of 10-50cm, ensuring that the high sound pressure level microphone 6 is directly facing the sound hole to avoid angular deviation affecting measurement accuracy. After confirming correct positioning, wait for the alarm to trigger or start real-time measurement via control button 2. If the device has an integrated status indicator light, it will be green, indicating normal acquisition status. When the alarm emits a high sound pressure pulse signal, the high sound pressure level microphone 6 first captures the sound wave signal. Its built-in stainless steel explosion-proof mesh effectively blocks airflow impact, protecting the microphone diaphragm from damage. Subsequently, the sound wave signal is converted into an electrical signal and transmitted to the high dynamic range acquisition circuit on the circuit board. The electrical signal is first amplified by a preamplifier with switchable gain. If the input signal strength exceeds a preset threshold, the circuit will automatically switch to a low gain level to prevent overload. The amplified analog signal is then converted into a digital signal by a high-precision analog-to-digital converter, fully preserving the high-frequency characteristics and peak information of the pulse signal.

[0031] The digital signal is then transmitted to the signal processing unit on the circuit board. The processor in the unit runs a pulse peak detection algorithm to calculate the instantaneous sound pressure level in real time and locks the detected peak data (manually triggered by control button 2). Finally, the measurement results are presented visually on the display screen 4, prioritizing the peak sound pressure level and the maximum sound pressure level. If the peak data reaches the valid measurement standard, the status indicator light will turn red to remind the measurement personnel to record the data. During the measurement process, the personnel can also manually switch the range, lock the current peak value, or reset the measurement using control button 2 to meet the operational needs of different scenarios. After a single measurement is completed, the measurement can be stopped by control button 2. The device will automatically save the measurement data. If it is necessary to continue measuring other alarms, the above positioning, acquisition, and processing steps can be repeated. If the measurement is completely finished, turn off the power switch, reinstall the protective cover 8 to protect the high sound pressure microphone 6, remove the tripod (if used), and complete the equipment storage.

[0032] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A near-field alarm sound level measuring instrument, comprising a housing (1), characterized in that: The front side of the housing (1) is provided with control buttons (2) and display screen (4). The upper end of the housing (1) is fixedly connected to a high sound pressure level microphone (6). The high sound pressure level microphone (6) is a pre-polarized condenser microphone core with a built-in stainless steel explosion-proof mesh. The housing (1) is provided with a circuit board. The installation position of the control buttons (2) corresponds to the contact points on the circuit board. The display screen (4) and the high sound pressure level microphone (6) are electrically connected to the circuit board through wires. The upper end of the housing (1) is equipped with a laser locator (5).

2. The near-field alarm sound level measuring instrument according to claim 1, characterized in that: The circuit board is equipped with a high dynamic range acquisition circuit and a signal processing unit. The high dynamic range acquisition circuit includes a preamplifier and an analog-to-digital converter.

3. A near-field alarm sound level measuring instrument according to claim 1, characterized in that: The shell (1) is provided with multiple anti-slip grooves (3) on both the left and right sides, and the multiple anti-slip grooves (3) are all inclined.

4. A near-field alarm sound level measuring instrument according to claim 1, characterized in that: The rear side of the housing (1) is provided with a tripod interface (7).

5. A near-field alarm sound level measuring instrument according to claim 1, characterized in that: A connecting ring (9) is fixedly connected to the upper end of the housing (1). A protective cover (8) is provided at the upper end of the connecting ring (9). An annular block (10) is fixedly connected to the inner wall of the protective cover (8). A slot (11) is provided on both the left and right sides of the annular block (10). A rectangular cavity (17) is symmetrically provided inside the connecting ring (9). A rotating shaft (14) is rotatably connected to the inner walls of the front and rear sides of the rectangular cavity (17). A vertical rod (13) is fixedly connected to the rotating shaft (14). A protrusion (12) is fixedly connected to the upper end of the vertical rod (13). An opening is provided on the adjacent sides of the two rectangular cavities (17). The two protrusions (12) penetrate the opening. The vertical rod (13) is elastically connected to the inner wall of the corresponding rectangular cavity (17) by a spring (15).

6. A near-field alarm sound level measuring instrument according to claim 5, characterized in that: Both rectangular cavities (17) have strip channels on opposite sides, and both vertical rods (13) are rotatably connected to pressure rods (16) on opposite sides. Both pressure rods (16) extend to the outside through the corresponding strip channels.

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