CN86100557B - Speed-adjustable light chopper - Google Patents
Speed-adjustable light chopper Download PDFInfo
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- CN86100557B CN86100557B CN86100557A CN86100557A CN86100557B CN 86100557 B CN86100557 B CN 86100557B CN 86100557 A CN86100557 A CN 86100557A CN 86100557 A CN86100557 A CN 86100557A CN 86100557 B CN86100557 B CN 86100557B
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- speed
- chopper
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Abstract
The present invention relates to a light chopper with variable speed, which belongs to the technical fields of optics and photoacoustics. The light chopper is mainly used for the mechanical modulation of a light beam and uses two non-linear frequency voltage converters with simple structure, and the two non-linear frequency voltage converters are combined by a subtracter. When the element parameters of the two non-linear frequency voltage converters are consistent, linear relation between the input and the output of the light chopper with variable speed can be realized. The present invention has the advantages of simple structure, stable performance, high precision, low cost and easy fabrication.
Description
The invention belongs to the mechanical type beam modulator that uses in optics and the acoustooptics.
Both at home and abroad, speed-adjustable light chopper has various ways.For example, the method that has is to adopt a chopper disk, by light activated element with the make-and-break signal of light path as feedback speed signal, the square-wave signal given this signal and frequency carries out bit comparison mutually, it is phase demodulation, carry out phase locking by circuit again, the shortcoming of this method is a complex circuit, costs an arm and a leg; The method that has adopts stepper motor as the speed governing element, and with a standard oscillator that frequency is very stable, behind pulsqe distributor and power amplifier, drive stepping motor is rotated.The characteristics of this method are that frequency stability is good, temperature drift is little, but the principle of work that is limited to stepper motor, the rotating manner of its rotating shaft between each step angle jumps, thereby make chopper disk in the process of modulated beam of light, produce additional phase noise, thereby the sensitivity of whole measuring system is reduced, and this method is still not ideal enough.
On basis with reference to previous work, the present invention proposes a kind of simply, reliable, stable method makes the chopper frequency of speed-adjustable light chopper and the frequency of control signal, or voltage, or electric current is big or small linear.
The main points of this speed-adjustable light chopper of the present invention are to have used two non-linear frequency voltage changers (3) simple in structure on design philosophy, (4), utilize a subtracter (5) with these two non-linear frequency voltage changers (3), (4) combine.When two transducers (3), when the component parameters of (4) is consistent, two transducers (3), the incoming frequency of (4) is just corresponding one by one, thus the linearity between input of realization chopper and the output is got in touch.
The present invention compared with prior art has the following advantages:
(1) the present invention utilizes two simple nonlinear F/V converters (3), (4), with the combination of a subtracter (5), can realize speed-adjustable light chopper input and output between linearity get in touch.
(2) two non-linear frequency voltage changers of the present invention (3), the incoming frequency of (4) and the nonlinear relationship between the output voltage are the transition means of setting up above-mentioned this linear contact.
(3) control mode of the present invention can adopt frequency signal, d. c. voltage signal or dc current signal.
Detailed content below in conjunction with accompanying drawing narration invention:
Fig. 1 is the structure principle chart of speed-adjustable light chopper elementary cell (G).
Fig. 2 is non-linear frequency voltage changer (3), the input-output characteristic curve of (4).
Fig. 3 is non-linear frequency voltage changer (3), the circuit theory diagrams of (4).
Fig. 4 is two non-linear frequency voltage changers (3), the combinational circuit schematic diagram of (4) and subtracter (5).
Fig. 5 is proportional integral derivative regulator (6), the circuit theory diagrams of analog line driver (7) and varying-speed motor (8).
Fig. 6 is speed-frequency converter (9), the circuit structure schematic diagram of chopper disk (10) and chopper frequency converter (11).
Fig. 7 is for adopting the embodiment of frequency signal as the input control signal of speed-adjustable light chopper.
Fig. 8 is for adopting the embodiment of d. c. voltage signal as the input signal of speed-adjustable light chopper.
Fig. 9 is for adopting the embodiment of dc current signal as the input signal of speed-adjustable light chopper.
The present invention as shown in Figure 1, by control signal (1), input socket (2), non-linear frequency voltage changer (3), (4), subtracter (5), proportional integral derivative regulator (6), analog line driver (7), varying-speed motor (8), speed-frequency converter (9), chopper disk (10), chopper frequency converter (11), accessory power outlet (12) is formed.Part (G) in the frame of broken lines is the elementary cell of speed-adjustable light chopper.
Principle of work is as follows: control signal (1) is that a frequency is f
1Continuous square-wave signal, by socket (2), be sent to non-linear frequency voltage changer (3), (Fig. 2 a) converts respective output voltages U to according to the input-output characteristic curve of non-linear frequency voltage changer (3)
1, be sent to the in-phase end of subtracter (5).Speed-frequency converter (9) is connected with the rotating shaft of varying-speed motor (8), and it becomes frequency signal f linearly with the tach signal (n) of varying-speed motor (8)
2(f
2=K
2And then be sent to non-linear frequency voltage changer (4) n).Equally, the input-output characteristic curve (Fig. 2 b) according to non-linear frequency voltage changer (4) converts corresponding output voltage U to
2, be sent to the end of oppisite phase of subtracter (5).In just moment of start, the rotating speed of varying-speed motor (8) is zero (n=0), f=0 then, u=0.So, a big positive voltage appears in the output terminal of subtracter (5), be sent to the input end of proportional integral derivative regulator (6) again, through its inner RC network, the output voltage of regulator (6) is increased sharply, through analog line driver (7) varying-speed motor (8) is started rapidly, rotating speed increases gradually, the output frequency f of speed-frequency converter (9)
2Also increase gradually.Because f
2Increase, f
1With f
2Difference diminish u
1With u
2Difference also diminish thereupon, the output voltage of subtracter (5) also diminishes thereupon, the output voltage of regulator (6) increases lentamente, the rotating speed of varying-speed motor (8) also increases lentamente.In case work as f
2＞f
1The time, u is just arranged
2＞u
1So subtracter (5) is output as negative voltage, through RC proportional integral derivative link, regulator (6) output voltage just reduces lentamente, and the rotating speed of varying-speed motor (8) is just done slight change, until f
2=f
1, subtracter (5) is output as zero, and regulator (6) just near this critical point, is constantly kept varying-speed motor (8) and is done the constant speed rotation.At this moment, the chopper disk (10) that is contained in varying-speed motor (8) rotating shaft is also done the constant speed rotation, and the light beam of incident is by mechanically break-make modulation of chopper disk (10).Because the number of various chopper disks (10) light hole is different, therefore the break-make number of times of light is changed into electric frequency signal with chopper frequency converter (11), export by socket (12).
Non-linear frequency voltage changer (3), the implementation detail of (4) is referring to Fig. 3.Be input as a continuous square-wave signal, through being sent to d type flip flop (14) after phase inverter (13) shaping, the S termination of d type flip flop (14) has electric capacity (15), cross-over connection resistance (16) and diode (17) between S end and Q end, after the CP of d type flip flop (14) end was subjected to trigger action, the state of Q end promptly became 1 by 0, charge to electric capacity (15) through resistance (16), after postponing after a while, the voltage of S end is raised to puts 1 unblocked level, and the state of Q end promptly is returned to 0 by 1.Meanwhile, diode (17) discharges the electric charge on the electric capacity (15).In this course, the Q end is just exported the fixing negative pulse square-wave signal of a width, becomes positive pulse through phase inverter (18).This pulse signal after the two-stage low-pass filter filtering that resistance (21) and electric capacity (22) are formed, is sent to the emitter follower that is made of operational amplifier (23) by by resistance (19) and electric capacity (20), exports through after the impedance conversion.The family curve of this circuit (Fig. 2) is non-linear.
Two non-linear frequency voltage changers (3), the implementation detail of (4) and subtracter (5) combination is referring to Fig. 4.Control signal (1) is that frequency is f
1The square wave continuous signal, be sent to non-linear frequency voltage changer (3), it exports U
1Be sent to the in-phase end of operational amplifier (28) through resistance (24).Frequency from speed-frequency converter (9) is f
2The square wave continuous signal be admitted to non-linear frequency voltage changer (4), it exports U
2Be sent to the end of oppisite phase of operational amplifier (28) through resistance (26).Resistance (25), (27) are used for determining the scale-up factor of subtracter (5).When two transducers (3), when the component parameters of (4) was consistent, these two transducers (3), the output voltage of (4) were also equal, i.e. U
1=U
2=U.As shown in Figure 2, both incoming frequencies are also equal, i.e. f
1=f
2=f.Just set up the frequency f of control signal thus
1Frequency f with tach signal
2Between relation one to one.Here, two transducers (3), (4) institute unintentional nonlinearity characteristic own has only played a transitional function, and is irrelevant with net result.
Proportional integral derivative regulator (6), the implementation detail of analog line driver (7) and varying-speed motor (8) is referring to Fig. 5.The output signal of subtracter (5) is sent into the proportional integral derivative regulator of being made up of operational amplifier (30) (6) through resistance (29).The scale-up factor K of its RC network is by resistance (29), and (31) are determined, K=-R31/R29.Derivative time constant τ
DDetermine τ by potentiometer (32) and electric capacity (33)
D=R32.C33.Integration time constant τ
1By resistance (31), (32) and electric capacity (33) are determined, τ
1=(R31+R32) C33.The output of regulator (6) is sent into analog line driver (7) through resistance (34).Resistance (39) is feedback resistance.The output of operational amplifier (36) is sent to middle pliotron (40) through over-compensation diode (38) and resistance (39), remove to promote large power triode (41) again, resistance (42) is the base resistance of large power triode, resistance (43) is connected in parallel on the two ends of varying-speed motor (8), when varying-speed motor (8) was opened a way, resistance (43) will be as the pull-up resistor of analog line driver (7).
Speed-frequency converter (9), the implementation detail of chopper disk (10) and chopper frequency converter (11) is referring to Fig. 6.Chopper disk (10) and tachometer disc (44) are fixed in the rotating shaft (45) of varying-speed motor (8) at a distance of certain spacing distance, do rotation synchronously with varying-speed motor (80).As light source, resistance (47) is current-limiting resistance to speed-frequency converter (9) with light emitting diode (46).In tachometer disc (44) rotating process, light beam is by the light hole (48) on the dish, with light directive phototriode (49).Resistance (50), diode (51) and potentiometer (52) they are the critical biasing circuit that ends of triode (53), and resistance (54) is its collector resistance, according to the number of times of light break-make, and the corresponding square wave continuous signal of output frequency (55).In like manner, as light source, resistance (57) plays metering function to chopper frequency converter (11) with light emitting diode (56).When chopper disk (10) rotated, light beam was by the light hole (58) on the dish, with light directive phototriode (59).Resistance (60), diode (61) and potentiometer (62) are the critical by biasing circuit of triode (63), and resistance (64) is its collector resistance.Triode (65) and resistance (66) constitute a phase inverter, and chopper frequency signal shaping is become square wave continuous signal (67), are sent to accessory power outlet (12) again.
The brief description invention is respectively frequency signal in control signal, three practical applications when d. c. voltage signal and dc current signal.
(1) with the implementation detail of frequency signal, referring to Fig. 7 as the input control signal of speed-adjustable light chopper.Phase inverter (68), (69), (70), (71), potentiometer (72), resistance (73) and electric capacity (74) constitute a ring oscillator, and oscillation frequency is f
c, be sent to elementary cell (G) through input socket (2).The chopper frequency f of chopper can pass through accessory power outlet (12), and an external digital frequency meter (75) monitors.The frequency f of actual measurement control signal
cAnd be fabulous linear relationship between the chopper frequency f.Frequency stability is ± 0.2%/hour.Used oscillator in this example can adopt the oscillator of any level match.
(2) with the implementation detail of d. c. voltage signal, referring to Fig. 8 as the input control signal of speed-adjustable light chopper.Voltage source (76) produces an adjustable direct-current control voltage U
c, through voltage controlled oscillator (77), with d. c. voltage signal U
cChange frequency signal f into
c, be sent to elementary cell (G) through input socket (2).Similar with the example of Fig. 7, if the voltage-frequency characteristic of voltage controlled oscillator (7) is linear, the voltage magnitude U of control signal then
cAnd it is linear between the chopper frequency.
(3) with the implementation detail of dc current signal, referring to Fig. 9 as the input control signal of speed-adjustable light chopper.Current source (78) produces an adjustable DC control electric current I
c, this current signal is delivered to the in-phase input end and the resistance (80) of the emitter follower that is made of high input impedance operational amplifier (79) simultaneously.Because so the not power taking of input end of high input impedance operational amplifier stream is the DC control electric current I
cAll flow through resistance (80), going up the voltage drop that forms at resistance (80) is exactly direct-current control voltage U
cEqually, through voltage controlled oscillator (77), with d. c. voltage signal U
cChange frequency signal f into
c, pass through input socket (2) again and be sent to elementary cell (G).Similar with the example of Fig. 8, the DC control electric current I
cAnd it is linear between the chopper frequency.
Claims (3)
1, a kind of speed-adjustable light chopper that belongs to optics and photoacoustics field, by control signal (1), subtracter (5), proportional integral derivative regulator (6), analog line driver (7), varying-speed motor (8), speed-frequency converter (9), chopper disk (10), chopper frequency converter (11) is formed, it is characterized in that having adopted two non-linear frequency voltage changers (3), (4) output is access in the in-phase input end and the inverting input of subtracter (5) respectively, and the adjusting through proportional integral derivative regulator (6) makes two non-linear frequency voltage changers (3), (4) incoming frequency is corresponding one by one, thereby the linearity between realization speed-adjustable light chopper input control signal and the output chopper frequency is got in touch.
2, non-linear frequency voltage changer according to claim 1 (3), (4) is characterized in that by d type flip flop (14), Sheffer stroke gate (13), (18), resistance (16), (19), (21), diode (17), electric capacity (15), (20), (22), operational amplifier (23) is formed, and is nonlinear relationship between its incoming frequency and the output voltage.
3, speed-adjustable light chopper according to claim 1 is characterized in that two non-linear frequency voltage changers (3), and the component parameters of (4) must be consistent.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN86100557A CN86100557B (en) | 1986-04-12 | 1986-04-12 | Speed-adjustable light chopper |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN86100557A CN86100557B (en) | 1986-04-12 | 1986-04-12 | Speed-adjustable light chopper |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN86100557B true CN86100557B (en) | 1987-02-25 |
| CN86100557A CN86100557A (en) | 1987-02-25 |
Family
ID=4801088
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN86100557A Expired CN86100557B (en) | 1986-04-12 | 1986-04-12 | Speed-adjustable light chopper |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN86100557B (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1295542C (en) * | 2004-12-15 | 2007-01-17 | 中国科学院上海光学精密机械研究所 | Transparent and reflective light chopper |
| CN101086475B (en) * | 2006-06-09 | 2011-11-30 | 深圳迈瑞生物医疗电子股份有限公司 | Air measuring device with rotation speed automatic control function and air measuring method |
| CN101958712B (en) * | 2010-11-10 | 2012-06-06 | 南京大学 | Analog phase-locked loop circuit without phase difference |
| CN111965809A (en) * | 2020-07-31 | 2020-11-20 | 电子科技大学 | Adjustable attenuator for ultraviolet/infrared/visible light full wave band |
-
1986
- 1986-04-12 CN CN86100557A patent/CN86100557B/en not_active Expired
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| Publication number | Publication date |
|---|---|
| CN86100557A (en) | 1987-02-25 |
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