A speed measurement system for sub-millimeter particles

Abstract

The application discloses a velocity measurement system for submillimeter particles, and belongs to the technical field of velocity measurement systems. The submillimeter velocity measurement net target is designed by using a flexible printed circuit (FPC) film. The submillimeter velocity measurement net target device comprises at least two FPC film net targets which are respectively fixed at corresponding positions of a net target device at specific target distances. The microsecond time measuring instrument comprises at least one time measuring channel. Each time measuring channel is composed of a signal conditioning module and a timing display module. When submillimeter particles pass through the two FPC film net targets in sequence, corresponding signal conditioning modules output target passing signals to the timing display module, and the running time of the submillimeter particles passing through the two FPC film net targets is measured and displayed. The application provides a simple and effective testing method for solving the problem of measuring the velocity of submillimeter particles.

Description

Technical Field

[0001] This invention relates to a velocity measurement system, and more particularly to a velocity measurement system for submillimeter particles, belonging to the technical field of velocity measurement systems. Background Technology

[0002] Doppler velocity radar method: Doppler velocity radar utilizes the Doppler effect and consists of a high-frequency transmitting and receiving antenna, a fixed device, an amplification module, a filtering module, a signal processing module, a control module, and a display module. It has high measurement accuracy.

[0003] However, it requires the electromagnetic waves to be reflected by the object being measured, and is limited by the radar's resolution capability. It is mainly suitable for measuring the speed of large moving objects. Moreover, Doppler speed radar is expensive, difficult to debug, and requires professional personnel to operate.

[0004] High-speed photography: This method uses a high-speed camera to continuously capture and record the time and space information of a moving object within a specific time period. The time information is recorded using time stamps, shooting frequency, or shooting time, while the spatial information is represented by images. High-frequency shooting can be used to measure the attitude and speed of a moving object.

[0005] However, since high-speed cameras need to capture and calculate images frame by frame, their testing accuracy depends on the camera's performance. Speed ​​measurement is limited by the camera's frame rate. Furthermore, high-speed photography has high requirements for ambient light. When moving objects are in environments with strong firelight and a lot of smoke and dust, it has a significant impact on image capture. Similar to Doppler velocimetry radar, high-speed cameras are also expensive, and the equipment is complex to debug. It is necessary to set aperture and exposure time technical parameters, and it must be operated by professionals.

[0006] Interception device velocity measurement method: Utilizing the principle of intercept velocity measurement, this method records the time it takes for a moving object to pass through the two target surfaces of targets I and II placed one after the other within a certain interval. The time difference between the two targets is then calculated, and the average velocity of the projectile between the two targets is calculated based on the known target distance. According to whether the projectile contacts the velocity measuring target, it is divided into two main categories: contact targets and non-contact targets. Common contact targets include metal wire mesh targets, metal foil targets, and epoxy fiberglass cloth laminate (FR-4) printed circuit targets. Common non-contact targets include electromagnetic coil targets, canopy targets, and light curtain targets. The advantage of non-contact targets is that they do not affect the speed and attitude of the moving object, do not damage the target, and have high efficiency.

[0007] However, it is easily affected by the external environment. When the moving object is in a strong fire or a lot of smoke, the sky curtain target and light curtain target cannot be used. The electromagnetic coil target cannot be applied to the moving object of non-magnetic material. The target surface used by the contact measurement method is mainly the on / off target. The signal of the moving object passing through the target is obtained by the interruption or conduction of the circuit when the moving object passes through the target surface. The advantage of the contact measurement method is that it is not easily affected by the external environment of fire and a lot of smoke, and has strong anti-interference ability. However, the contact measurement requires contact with the moving object, which will affect the posture of the moving object and introduce errors into the test results. The test accuracy is lower than that of non-contact measurement.

[0008] To address this problem, a velocity measurement system for submillimeter particles is proposed. Summary of the Invention

[0009] The main objective of this invention is to provide a velocity measurement system for submillimeter particles.

[0010] The objective of this invention can be achieved by adopting the following technical solution:

[0011] A velocity measurement system for submillimeter particles comprises a submillimeter velocity measuring target device and a microsecond timing instrument. The submillimeter velocity measuring target device consists of at least two flexible printed circuit (FPC) thin-film target-type cutoff sensors fixed at corresponding positions on the target device at a specific target distance. Each pair of FPC thin-film targets forms a group, with the first FPC thin-film target serving as the start target (Target I) and the second FPC thin-film target serving as the stop target (Target II). The microsecond timing instrument includes at least one timing channel, each consisting of a signal conditioning module and a timing display module. The signal conditioning module converts the on-off state change of the FPC thin-film target into a voltage transition signal. The timing module employs a dual-pulse timing mode, using the Target I signal as the timing start signal and the Target II signal as the timing stop signal, recording the time interval between the falling edge of the Target I signal and the falling edge of the Target II signal.

[0012] The FPC thin film mesh target type intercept sensor is designed based on the principle of open-circuit intercept velocity measurement. The top layer of the FPC thin film has a “n” shaped back-and-forth routing of lines. The copper foil wire diameter and the line spacing are both d (d≤ one-third of the smallest size of the submillimeter particle being measured), which are densely woven into a mesh. The size of the mesh is designed according to the actual needs of the submillimeter particle being measured. The thickness of the effective target area is 0.07mm.

[0013] The FPC thin film target lead wire pads are designed with a double-sided wiring method, and their total thickness is 0.11mm.

[0014] The timing module adopts a single-trigger mode. After the reset button is pressed to reset and clear the time, the "ready" status indicator lights of target I and target II light up, indicating that the timing is ready and waiting for the first falling edge of the input signal of target I to start the timing and the first falling edge of the input signal of target II to stop the timing. The time interval value of the two falling edges is displayed on the 6-digit LED digital tube.

[0015] The timing module only responds to the first falling edge of the input signals from target I and target II. After the reset button is pressed again to reset and clear the data, the "ready" status indicator lights of target I and target II will light up, and a new round of timing measurement can begin.

[0016] The signal conditioning module consists of an on / off switching circuit, a reset circuit, a signal conversion circuit, and a state conversion circuit. The on / off switching circuit and the signal conversion circuit convert the over-target signal of the FPC thin film target into a voltage jump signal and shape it into the required timing signal. The reset circuit performs the reset and zeroing function of the timing instrument. The state conversion circuit implements the single trigger function.

[0017] The on / off switching circuit is used to convert the state change of the FPC thin film target from on to off into a voltage jump signal. When the FPC thin film target is on, the "path" status indicator light is on; when a submillimeter particle passes through the FPC thin film target, the "path" status indicator light is off, the on / off state circuit changes from a conducting state to an open state, and outputs a positive pulse signal to the signal conversion circuit.

[0018] The reset circuit provides a low-level signal with a pulse width greater than 20ms to reset the state transition circuit and the timing display module. When the reset button is pressed, the "ready" status indicator light of the state transition circuit illuminates; the digital tube of the timing display module displays 000000, indicating that the timing is ready.

[0019] The signal conversion circuit uses a monostable multivibrator to shape the positive pulse signal input to the on / off switching circuit and output a low-level signal with a pulse width greater than 20ms to the magnetic latching relay of the state switching circuit. The monostable multivibrator... The output pulse width Tw = 1 / 2RC, and the values ​​of the timing resistor R and timing capacitor C must ensure that the pulse width Tw is greater than 20ms.

[0020] The state transition circuit employs a dual-coil controlled double-pole double-throw magnetic latching relay design. The first coil is used for the state preparation circuit, and the second coil is used for the state triggering circuit. The state preparation circuit is controlled by a reset button. When the reset button is pressed for more than 20ms, the first coil controls the magnetic latching relay to close, achieving a reset and zeroing. The corresponding channel's "Ready" indicator light illuminates, and the timing channel is activated, indicating that timing is ready. The state triggering circuit is controlled by a monostable multivibrator. When the monostable multivibrator... The output pulse width Tw is a low-level signal greater than 20ms. The second coil controls the magnetic latching relay to open, the "ready" indicator light of the corresponding channel goes out, and the timing channel is disconnected.

[0021] The state transition circuit only responds to the first falling edge of the input signals of target I and target II. After the reset button is pressed again to reset and clear the data, the "ready" status indicator lights of target I and target II will light up, and a new round of timing measurement can begin.

[0022] The timing display module starts timing at the first falling edge of the input signal from target I and stops timing at the first falling edge of the input signal from target II, and displays the time interval between the two falling edges on a 6-digit LED display.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] ① It realizes the velocity measurement of sub-millimeter particles and provides a velocity measurement system suitable for complex and harsh environments and occasions with limited installation space;

[0025] ② It has a simple structure, is easy to operate, and is suitable for various test sites;

[0026] ③ Low cost, economical and practical, high cost performance. Attached Figure Description

[0027] Figure 1 This is a block diagram of the submillimeter particle velocity measurement system according to Embodiment 1 of the present invention.

[0028] Figure 2 This is the 3D model of the FPC thin film target according to Embodiment 1 of the present invention.

[0029] Figure 3 This is a partial enlarged view of the wiring on the top layer of the FPC thin film target according to Embodiment 1 of the present invention.

[0030] Figure 4 This is a circuit schematic diagram of the signal conditioning module according to Embodiment 1 of the present invention. Detailed Implementation

[0031] To enable those skilled in the art to understand the technical solution of the present invention more clearly, the present invention will be further described in detail below with reference to the embodiments and accompanying drawings, but the embodiments of the present invention are not limited thereto.

[0032] like Figures 1-4 As shown, this embodiment provides a velocity measurement system for submillimeter particles. Figure 1 The diagram shown is a block diagram of the submillimeter particle velocity measurement system according to Embodiment 1 of the present invention, which includes a submillimeter velocity measurement net target device and a microsecond timing instrument.

[0033] The submillimeter velocity measuring net target device consists of two flexible printed circuit (FPC) thin-film net target-type cutoff sensors (see...). Figure 2 The device consists of two FPC film net targets fixed at specific target distances at the front and rear ends, as shown in the figure. The front end of the FPC film net target serves as the starting target (Target I), and the rear end of the FPC film net target serves as the stopping target (Target II).

[0034] The aforementioned FPC thin film target-type cutoff sensor is designed based on the principle of open-circuit cutoff velocity measurement. The top layer of the FPC thin film has a zigzag pattern of reciprocating lines (e.g., ...). Figure 3 As shown), the copper foil wire diameter is 0.077mm (as shown). Figure 3 As shown), the line spacing is 0.077mm (as shown). Figure 3 As shown), it is densely woven into a mesh, with a mesh size of 100×100mm2. The thickness of the effective target area is 0.07mm, and its resistance is no greater than 500Ω.

[0035] The FPC thin film target lead wire pads are designed with a double-sided wiring method, and their total thickness is 0.11mm.

[0036] The timing module adopts a single-trigger mode. After the reset button is pressed to reset and clear the time, the "ready" status indicator lights of target I and target II will light up, indicating that the timing is ready and waiting for the first falling edge of the input signal from target I to start the timing and the first falling edge of the input signal from target II to stop the timing. The time interval between the two falling edges is displayed on a 6-digit LED digital tube with an accuracy level of 1μs and a minimum timing of ≥5μs.

[0037] The timing module only responds to the first falling edge of the input signals from target I and target II. After pressing the "RESET" button again to reset and clear the data, the "ready" status indicator lights of target I and target II will light up, and a new round of timing measurement can begin.

[0038] Figure 4The circuit diagram of the signal conditioning module according to Embodiment 1 of the present invention is shown below. The on / off state circuit consists of current-limiting resistors R1 and R2, "path" status indicator lights LED3 and LED4, and FPC1 (target I) and FPC2 (target II). The signal conversion circuit consists of a monostable multivibrator U1, timing resistors R3 and R4, timing capacitors C2 and C3, and a bypass capacitor C1. The reset circuit consists of a reset button SW1 and a current-limiting resistor R7. The state conversion circuit consists of "ready" status indicator lights LED1 and LED2, current-limiting resistors R5 and R6, protection diodes D1-D6, and dual-coil double-pole double-throw magnetic latching relays K1-K2.

[0039] exist Figure 4 In the on / off state circuit, pin 1 of FPC1 (Target I) is connected to the 0V terminal of the signal conditioning module, pin 2 is connected to pin 2 of the "path" status indicator LED3, pin 1 of the "path" status indicator LED3 is connected to pin 1 of the current-limiting resistor R1, and pin 2 of the current-limiting resistor R1 is connected to the VCC terminal of the signal conditioning module. Similarly, pin 1 of FPC2 (Target II) is connected to the 0V terminal of the signal conditioning module, pin 2 is connected to pin 2 of the "path" status indicator LED4, pin 1 of the "path" status indicator LED4 is connected to pin 1 of the current-limiting resistor R2, and pin 2 of the current-limiting resistor R2 is connected to the VCC terminal of the signal conditioning module. When FPC1 (Target I) and FPC2 (Target II) are connected and powered on, the "path" status indicators LED3 and LED4 light up, indicating that the timing path is ready.

[0040] exist Figure 4 In the signal conversion circuit, the monostable multivibrator U1 is a dual-channel monostable CMOS multivibrator. The positive trigger terminal (pin 4) of the first monostable multivibrator U1.1 is connected to the input signal of target I, and the positive trigger terminal (pin 12) of the second monostable multivibrator U1.2 is connected to the input signal of target II. The U1.1... The output pulse width Tw1 = 1 / 2R3C2, and the U1.2 of The output pulse width Tw2 = 1 / 2R4C3. The values ​​of timing resistors R3 and R4, and timing capacitors C2 and C3 must ensure that Tw1 and Tw2 are greater than 20ms. The monostable multivibrator U1.1... The terminal (pin 7) is connected to the first common terminal (pin 3) and the "-" terminal (pin 6) of the second coil of the magnetic latching relay K1, and the monostable trigger U1.2... The terminal (pin 9) is connected to the first common terminal (pin 3) and the "-" terminal (pin 6) of the second coil of the magnetic latching relay K2.

[0041] exist Figure 4 In the reset circuit, pin 2 of the reset button SW1 is connected to the 0V terminal of the signal conditioning module, and pin 1 is connected to pin 1 of the current-limiting resistor R7 and pins 2 of the protection diodes D2 and D3 in the state transition circuit. Pin 2 of the current-limiting resistor R7 is connected to the VCC terminal of the signal conditioning module. When the reset button SW1 > 20ms, the magnetic latching relays K1 and K2 close, the "ready" status indicator LEDs LED1 and LED2 light up, and the monostable trigger U1.1... The terminal (pin 7) is connected to terminal I of the timing display module, and the monostable trigger U1.2... The pin (pin 9) is connected to pin II of the timing display module.

[0042] exist Figure 4 In the state transition circuit, the second common terminal (pin 8) of the magnetic latching relay K1 is connected to the first normally open terminal (pin 4), the second normally open terminal (pin 7) is connected to pin 2 of the current limiting resistor R5, pin 1 of the current limiting resistor R5 is connected to pin 1 of the "ready" status indicator LED1, and pin 2 of the "ready" status indicator LED1 is connected to the 0V terminal of the signal conditioning module; the second common terminal (pin 8) of the magnetic latching relay K2 is connected to the first normally open terminal (pin 4), the second normally open terminal (pin 7) is connected to pin 2 of the current limiting resistor R6, pin 1 of the current limiting resistor R6 is connected to pin 1 of the "ready" status indicator LED2, and pin 2 of the "ready" status indicator LED2 is connected to the 0V terminal of the signal conditioning module.

[0043] Figure 4 The overall working process is as follows: ① After connecting FPC1 (Target I) and FPC2 (Target II), power is applied, and the "Circuit" status indicator LED3 and LED4 are lit, indicating that FPC1 and FPC2 have been successfully connected; ② Pressing the reset button SW1 causes the magnetic latching relays K1 and K2 to engage, illuminating the "Ready" status indicator LED1 and LED2, indicating that the timing circuit is ready; ③ When the test object passes through FPC1, FPC1 changes from conducting to disconnected, and the monostable multivibrator U1.1 outputs a start timing signal; ④ When the test object passes through FPC2, FPC2 changes from conducting to disconnected, and the monostable multivibrator U1.2 outputs a stop timing signal.

[0044] The above description is merely a further embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any substitutions or modifications made by those skilled in the art within the scope disclosed in the present invention, based on the technical solution and concept of the present invention, shall fall within the scope of protection of the present invention.

Claims

1. A velocity measurement system for submillimeter particles, comprising a submillimeter velocity measuring net target device and a microsecond timer coupled to the submillimeter velocity measuring net target device, characterized in that: The submillimeter velocity measuring net target device includes at least two flexible printed circuit thin film net target type cutoff sensors, which are respectively fixed at corresponding positions of the net target device at a specified target distance; The microsecond timer includes at least one timing channel, and each timing channel consists of a signal conditioning module and a timing display module; Each pair of flexible printed circuit thin film targets forms a group; Among them, the first flexible printed circuit thin film mesh target serves as the start target I, and the second flexible printed circuit thin film mesh target serves as the stop target II. The signal conditioning module converts the on-off state change of the flexible printed circuit thin-film mesh target into a voltage jump signal; The timing display module adopts a dual-pulse timing mode, using the start target I signal as the timing start signal and the stop target II signal as the timing stop signal, and records and displays the time interval from the falling edge of the start target I signal to the falling edge of the stop target II signal; The flexible printed circuit thin film mesh target type intercept sensor is designed based on the principle of open circuit intercept velocity measurement. The wiring distance of the mesh target circuit is at least 0.2mm from the four perimeter. The mesh target circuit adopts a single-sided wiring method, with the wiring running back and forth in an n-shape on the top or bottom layer of the flexible printed circuit film. The copper foil wire diameter and the line spacing are both d, densely woven into a mesh. The thickness of this mesh target surface is 0.07mm. The signal conditioning module includes an on / off switching circuit, a reset circuit, a signal conversion circuit, and a state conversion circuit; The on / off switching circuit and the signal conversion circuit convert the target-passing signal of the flexible printed circuit thin film target into a voltage jump signal and shape it into the required timing signal.

2. The velocity measurement system for submillimeter particles according to claim 1, characterized in that: The flexible printed circuit thin film target design has two terminals, and its pads adopt a double-sided wiring method with a total thickness of 0.11mm.

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