CN104634986A - Infrared photoelectric revolving speed meter - Google Patents

Abstract

An infrared photoelectric revolving speed meter comprises a rotor, an infrared photoelectric sensor and a secondary meter. The infrared photoelectric sensor is of conventional photoelectric auto-collimation structure and comprises an optical imaging system and a front-loaded amplifying circuit, infrared light of 0.94 micrometer in wavelength which is transmitted by a high-power monochromatic light emitting diode in the optical imaging system is incident to a semi-transmittance and semi-reflecting mirror through an aperture diaphragm, light spots are collected to the surface of a rotary axis of the rotor by a collecting lens and are inputted to the secondary meter through the front-loaded amplifying circuit. The secondary meter comprises a pulse shaping processing and frequency doubling circuit and a single-chip microcomputer processing system, and a single-chip microcomputer is connected with a monitor or outputs through a serial port. The infrared photoelectric revolving speed meter is convenient to mount, has low requirements for the surroundings and can easily measure the revolving speed. The measuring range ranges from 10 r/min to 100,000 r/min, and the infrared photoelectric revolving speed meter has wider dynamic measuring range and higher measuring accuracy.

Description

Infrared electro tachometer of measuring

Technical field

The present invention relates to a kind of measuring instrument, especially infrared electro tachometer of measuring.

Background technology

In commercial production and scientific experiment, the measurement of rotating speed is a very important problem.About the method measuring spinner velocity is also many, can more complicated mostly.Current tachometer of measuring measurement range is not wide, and measuring accuracy also has much room for improvement.

Summary of the invention

The technical matters that the application will solve overcomes above-mentioned defect, provides a kind of infrared electro tachometer of measuring.

For solving the problems of the technologies described above, the technical scheme of employing is:

Infrared electro tachometer of measuring, by rotor, infrared photoelectric sensor and secondary instrument composition, infrared photoelectric sensor adopts the straight structure of traditional photoelectric auto, comprise optical imaging system and pre-amplification circuit two parts, the wavelength that high power single color LED in optical imaging system sends is that the infrared light of 0.94 μm incides semi-transparent semi-reflecting lens through aperture diaphragm, then by condenser, luminous point is gathered on the rotating shaft surface of rotor, focus on the photosurface of the photodetector in optical imaging system after turning axle reflection, secondary instrument is inputed to through pre-amplification circuit, rotor turning axle is pasted the rectangle aluminium foil of a high reflectance, semi-transparent semi-reflecting lens plating take centre wavelength as the film of 0.94 μm, secondary instrument comprises shaping pulse process and frequency multiplier circuit, single-chip microcomputer signal processing system, peak detection circuit is formed by diode, resistance Rl and electric capacity C2, resistance R2 and R3 forms the bleeder circuit of crest voltage, peak detection circuit and bleeder circuit are connected LM3ll comparer respectively and form shaping pulse treatment circuit, after the phase-locking frequency multiplication circuit that integrated circuit CD4046 forms is delivered in the pulse of being crossed by shaping pulse processing circuit processes, deliver to single-chip microcomputer, single-chip microcomputer is connected display or is exported by serial port.

High speed amplifier LF357 is as prime amplifier, and 89C51 selected by single-chip microcomputer, has two Timer/Counter T0 and T1 in it.

Pre-amplification circuit and photodiode are sticked together, and is encapsulated in photoelectric sensor probe inside.

The invention has the beneficial effects as follows: easy for installation, not high to the environmental requirement of surrounding yet, the measurement of rotating speed can be completed easily.Test specification, from 10r/min to 100000r/min, has wider range of dynamic measurement, and measuring accuracy is also higher.

Accompanying drawing explanation

Fig. 1 is the simple block diagram of this knotmeter;

Fig. 2 is optical system schematic diagram;

Fig. 3 is pre-amplification circuit figure;

Fig. 4 is shaping pulse treatment circuit circuit diagram;

Fig. 5 is phase-locking frequency multiplication circuit circuit diagram.

Wherein, l. turning axle; 2. lens; 3. Amici prism; 4. light emitting diode.

Embodiment

Fig. 1 is infrared electro knotmeter measuring principle block diagram, and knotmeter is made up of the secondary instrument in photoelectric sensor and block scheme.The light that infrared photoelectric sensor sends, focuses on tested turning axle, and after light is reflected by rotating shaft, refocusing is on the photosurface of sensor photodetectors.On the rotary shaft, paste the rectangle aluminium foil of a high reflectance, when rotating shaft rotates, often turn around, photodetector will export a pulse signal.This pulse signal carries out signal transacting sending into secondary instrument in photoelectric sensor after enlarge leadingly.In secondary instrument, pulse signal is after Shape correction, and the rect.p. of formation rule, this pulse signal, again after 60 frequencys multiplication, is sent into single-chip microcomputer and carried out process calculating.In single-chip microcomputer, the method pulse signals utilizing two Timer/Counter T0 and T1 to combine carries out timer counter, realizes the survey calculation of rotor speed, and the rotor speed signal calculated directly can carry out numerical monitor, also can be exported by serial port.

Photoelectric whirl measuring apparatus is made up of primary instrument and infrared photoelectric sensor and secondary instrument and signal transacting computing system.Infrared photoelectric sensor adopts the straight structure of traditional photoelectric auto, utilizes highly sensitive photodetector as detecting element, comprises optical imaging system and pre-amplification circuit two parts.Fig. 2 is the light channel structure figure that we adopt.The wavelength that high-power single color LED sends is that the infrared light of 0.94 μm incides semi-transparent semi-reflecting lens through aperture diaphragm, then by condenser, luminous point is gathered on the surface of rotor, according to light path principle of reversibility, the luminous point on rotor surface is imaged onto on photodetector photosurface again by condenser and semi-transparent semi-reflecting lens.This structure is the straight photosensor structure of autocollimatic, enter, reflection ray along optical axis, mounting and adjusting is more for convenience.Semi-transparent semi-reflecting lens plating take centre wavelength as the film of 0.94 μm, enters optical system with the spurious rays stoping some to affect Photoelectric Detection.The size focusing on hot spot on the rotary shaft directly has influence on the sensitivity of measurement, if smaller at rotational speed one timing hot spot, so hot spot gets over the time in rectangular reflection interval very soon, and be reacted in pulse waveform, rising edge will be steeper.If hot spot is larger, so hot spot gets over the time in rectangular reflection interval relatively slowly, and thus the rising edge of its pulse signal exported will have certain gradient.For frequency measurement, the rising edge steeper frequency measurement resolution of pulse signal is higher.Therefore to calculate the Analyzing on Size of focal beam spot.The calculating of condenser position, the calculating of focal beam spot size, the imaging formula of Main Basis geometrical optics: l/l '-l/l=l/f(l) and enlargement ratio formula β=y '/y(2).In formula: l ' is image distance; L is object distance; F is focal length; Y ' is image height; Y is object height.The sensitive detection parts selected are highly sensitive photodiode detectors, and its sensitive wave length is just near 0.94 μm.Enlarge leadingly as shown in Figure 3.When rotating shaft rotates, often forward the rectangle aluminium foil place of high reverse--bias to, photodetector just exports a pulse signal.Amplify by exchanging, this pulse signal is amplified to certain amplitude.Select low noise, high speed amplifier LF357 is as prime amplifier.Because knotmeter often works in Workshop Production scene, spatial electromagnetic interference is very large, in order to the impact effectively avoided interference, selects SMD amplifier device, together with being done by pre-amplification circuit, and is encapsulated in photoelectric sensor probe inside with photodiode.Signal processing system and secondary instrument are by shaping pulse process and frequency multiplier circuit, and a few part such as single-chip microcomputer signal processing system forms.Owing to being subject to surrounding environment, the impact of the factors such as the distance of photodetector distance rotating shaft, the amplitude of the electric signal that amplifier exports will present fluctuations.In signal shaping treatment circuit, if adopt the way pulse signals of fixed level to carry out Shape correction, the output of reshaping signal may be affected.The method of floating threshold level is adopted effectively to address this problem.In the diagram, constitute peak detection circuit by diode, resistance Rl and electric capacity C2, detect the peak value size of pulse signal.Resistance R2 and R3 forms the bleeder circuit of crest voltage, utilizes the size of partial pressure value to compare in LM3ll comparer as comparative level and pulse signal, exports rectangular pulse signal, this signal is used for frequency measurement.During selection and comparison level, can, according to the output waveform of pulse signal, the place of signal rising edge steepest be selected to carry out binary conversion treatment.The amplitude of the reflected signal that this comparative level can receive according to detector, regulates the size of level automatically.When distance between sensor and rotating shaft changes, the pulse height of output will change to some extent, and comparative level also can change accordingly, ensure that normally carrying out of signal shaping, can not have influence on the output of rect.p..Thus, adopt this signal processing method, effectively can suppress the impact of undesired signal, increase stability and the reliability of system.Above-mentioned rect.p., send into the phase-locking frequency multiplication circuit be made up of integrated circuit CD4046, as shown in Figure 5, the input end of signal is PHil, output signal is taken out from the second phase comparator output terminal PHO2 of CD4046, the input end VCOl that level and smooth d. c. voltage signal adds to voltage controlled oscillator is become through loop filter, go to change the frequency that VCO produces oscillator signal, the signal of this frequency change is after the frequency divider be made up of two counter chip MCl4522 carries out l/60 frequency division, deliver to the comparison signal input end PHi2 of phase comparator, after loop reaches locking, input signal is identical with the frequency of feedback signal, thus the frequency of VCO output signal is exactly 60 times of frequency input signal, then this signal is sent into single-chip microcomputer and carry out the calculation process counting and ask rotating speed.The frequency measurement of pulse signals generally adopts two kinds of methods, and one is ranging pulse number within the set time, and two is the methods in ranging pulse cycle.First method, also exists the contradiction between the real-time of measurement and accuracy of measurement for low frequency signals.Want to improve accuracy of measurement, ranging pulse number must be increased, cause Measuring Time long, actual measurement process can not be applied to.Second method is suitable for measuring low frequency signal, but relatively low for high-frequency pulse signal measuring accuracy.Utilize two Timer/Counter of single-chip microcomputer, adopt the method that ranging pulse number and ranging pulse cycle combine, the real-time of tachometric survey can be reached, and the value that tests the speed of pin-point accuracy can be obtained in wider frequency range.Single chip computer89C51 has two Timer/Counter T0 and T1, utilize the pulse number N1 that T0 counter records photoelectric sensor exports, namely synchronization T1 counter measures sampling time t1 as benchmark number oscillation period in timer recorder, N1 reacts the rotational frequency of rotor, t1 refers to the tachometric survey time, can be calculated tachometer value by single-chip microcomputer.From initial time, the step-by-step counting that counter T0 exports photoelectric sensor, counter T1 counts benchmark as timer oscillation period simultaneously, when arriving predetermined time of testing the speed t1, single-chip microcomputer should send and stop counting instruction, because the pulse that now photoelectric sensor exports is not necessarily locate in the whole cycle just, so counter T1 still continues counting a period of time t2 to the machine datum cycle, until stop the work of counter T1 during the rising edge of next pulse signal, the ratio of the gate time (t1+t2) of count value N1 and the T1 of this hour counter T0 is the rotating speed size that will measure.Rotating speed is: r=N1/ (t1+t2).Select the crystal oscillator frequency of single chip computer89C51 to be 12MHz, therefore each reference period is 1 μ s, selects the time t1 that tests the speed to be 1s, substantially can accomplish Rotating speed measring fast.Spinner velocity, both directly can be carried out numerical monitor, also can be exported by serial port.

Claims (3)

1. infrared electro tachometer of measuring, it is characterized in that: by rotor, infrared photoelectric sensor and secondary instrument composition, infrared photoelectric sensor adopts the straight structure of traditional photoelectric auto, comprise optical imaging system and pre-amplification circuit two parts, the wavelength that high power single color LED in optical imaging system sends is that the infrared light of 0.94 μm incides semi-transparent semi-reflecting lens through aperture diaphragm, then by condenser, luminous point is gathered on the rotating shaft surface of rotor, focus on the photosurface of the photodetector in optical imaging system after turning axle reflection, secondary instrument is inputed to through pre-amplification circuit, rotor turning axle is pasted the rectangle aluminium foil of a high reflectance, semi-transparent semi-reflecting lens plating take centre wavelength as the film of 0.94 μm, secondary instrument comprises shaping pulse process and frequency multiplier circuit, single-chip microcomputer signal processing system, peak detection circuit is formed by diode, resistance Rl and electric capacity C2, resistance R2 and R3 forms the bleeder circuit of crest voltage, peak detection circuit and bleeder circuit are connected LM3ll comparer respectively and form shaping pulse treatment circuit, after the phase-locking frequency multiplication circuit that integrated circuit CD4046 forms is delivered in the pulse of being crossed by shaping pulse processing circuit processes, deliver to single-chip microcomputer, single-chip microcomputer is connected display or is exported by serial port.

2. infrared electro tachometer of measuring according to claim 1, is characterized in that: high speed amplifier LF357 is as prime amplifier, and 89C51 selected by single-chip microcomputer, has two Timer/Counter T0 and T1 in it.

3. infrared electro tachometer of measuring according to claim 1 and 2, is characterized in that: pre-amplification circuit and photodiode are sticked together, and is encapsulated in photoelectric sensor probe inside.