CN1086330A - Dual motor speed controller - Google Patents
Dual motor speed controller Download PDFInfo
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- CN1086330A CN1086330A CN92112396A CN92112396A CN1086330A CN 1086330 A CN1086330 A CN 1086330A CN 92112396 A CN92112396 A CN 92112396A CN 92112396 A CN92112396 A CN 92112396A CN 1086330 A CN1086330 A CN 1086330A
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Abstract
A kind of scanister that scans a target repeatedly, have a laser generator, two scanning motors and be used for respectively the dual motor speed control circuit of gated sweep motor speed independently, this dual motor speed control circuit comprises: one is used to utilize the frequency information that obtains from the input signal of the described dual motor speed control circuit of an input to control first motor control circuit of the speed of first motor; An and control circuit that is used to utilize duty factor information Control second motor speed that obtains from described input signal.The objective of the invention is to reduce the cost of control motor speed, and can produce multiple scanning patter.
Description
The present invention is the relevant laser scanning system that reads bar code symbol, the particularly relevant dual motor speed controller of controlling two scanning motors in laser scanning device.
Past, utilize the popularizing of bar code symbol of recognition value with the retailer, developed various barcode reading systems and device.Present most barcode reader is removable handheld laser scanning system.The user of these machines payes attention to size, weight and the electric power consumption of machine.One of this type systematic is to be recorded in United States Patent (USP) 4,496, No. 831 laser scanning bar code reading system.
Be recorded in United States Patent (USP) the 4th, 496, No. 831 laser scanning bar code reading system has the removable handheld scanner head of different shape, and one of aforementioned shapes is the shell of rifle type.In order to collect the various parts of laser scanning head, this canning jug and tube portion.These parts have comprised miniature light sources as semiconductor laser diode, comprise photoconduction that light source is produced to the compact optical system of the focus lamp of bar code symbol, detect from the small-sized pick-up unit of the light that bar code symbol reflected that is scanned.
During running, the compact optical system focuses on the light beam that laser diode produced, and directive is installed in the scanister in the scanner head tube portion light path, and this scanister swept away bar code symbol with laser beam.Scanister has a scanning motor with the length direction of the inswept symbol of light beam at least, and can have second motor with the Width of the inswept symbol of light beam.The axle that is installed in motor such as the reflective optical system of mirror is gone up light is derived exit portion directive mark.Then, detecting device detects the light that symbol reflects and is handled, and detecting device generally is made up of the photo-sensitive cell as photodiode.
The similar of each scanning motor is in simple step motor, its dissimilarity is that scanning motor is controlled by control device, this control device is that axle with motor is in the circumferencial directions vibration less than 360 degree, then again to opposite circumferencial directions vibration, at full speed repeat aforesaid circulation then and turn round less than 360 degree.
During by two scanning motor scanned symbol of use, can produce multirow and omnibearing scanning patter.For example for the scanning bar code symbol, and do the bilateral scanning of directions X and Y direction, can produce the scanning patter of grating type,, then can obtain the scanning patter of search type if two scanning motors drive with sinusoidal wave formula rate of change.The size of figure and shape are to control by the angular velocity of the angle of inclination of adjusting catoptron and/or scanning motor.Various scanning patters are recorded in United States Patent (USP) the 4th, 251, and No. 798,4,387, No. 297 and 4,871, in No. 904.These scanning patters can be used to scan the more complicated symbols such as symbol with two-dimensional bar or random orientation.
For the speed of monitor scans motor, United States Patent (USP) the 4th, 709 discloses the bar code scanner that uses hall effect device for No. 195.More detailed is that the output signal of a hall-effect switch is used as the input of motor detecting device.The motor detector circuit receives and the proportional voltage of frequency (being motor speed), with the minimum reference voltage of allowing responsiveness of the voltage that obtains and expression relatively, and the hypervelocity of output expression motor and the speed voltage signal of crossing the state of hanging down.These voltage signals are by microprocessor monitors, so that can take adequate measures according to the motor state.
Now, a kind of system of the two scanning motor speed of controlling laser scanning device respectively that can provide needs.And stronger pursuit can give the system of dirigibility on the laser scanning figure that laser scanning device produced.So an object of the present invention is to provide the dual motor control circuit that possesses aforementioned functional.
Use the scanner of LS9000 scanner of the present invention for " pilot lamp type ".The LS9000 scanner is with continuous mode operation.Scanning patter is to be projeced into the last or ground of table from pilot lamp.Actual scanning patter is the figure that reads the search type of bar code with comprehensive.
In order to produce the scanning patter of search type, used two opposite directions of deflection LASER Light Source rotary motor (with reference to subsequent figures 4).Change by two motor speed ratios produces various search type scanning patters.
The objective of the invention is to reduce the cost of control motor speed, and the device that can produce most scanning patters is provided.
The present invention is the dual motor speed control circuit of the speed of relevant two scanning motors of controlling in the laser scanning system respectively to be possessed.Control circuit of the present invention can be applicable to control the speed of two scanning motors of the portable scanner of the LS9000 laser scanner of making as SYMBOL TECHNOLOGY company, certainly, principle of the present invention and instruct the laser scanning device that all can adapt to and be applied in arbitrary form.An input signal that provides the laser scanner plate to set the required full detail of suitable scanning patter and motor speed is provided dual motor speed controller, and makes the selection of figure more flexible.In order to reach the speed of controlling two motor respectively, representational is the input signal of being supplied with variable frequency and duty factor by microprocessor.The frequency of input is used to set the speed of a motor, and the information that is included in the duty factor of input signal is the velocity contrast that is used to set first motor and second motor.The primary circuit of controlling first motor speed comprises one and is used to produce the counting assembly that frequency is first motor frequency control signal that requires the frequency that turns round and the feedback assembly of control first motor speed.The primary circuit of controlling second motor speed comprise integrating gear and that a duty factor according to input signal produces the variable DC voltage signal so as to the speed dependent that makes second motor in second feedback circuit above-mentioned variable DC voltage signal, that be used to control second motor speed.
The present invention is because with one of the control line decreased number of input scanner seat, so the method that reduces the cost of controlling two motor speed is provided.All signals are to transmit with signal, send into then not to be microprocessor board but necessary element in the laser scanner plate.Its result has reduced the part of microprocessor printed circuit board (PCB) reality, has also reduced the quantity of web member pin number and lead simultaneously.
Below, one embodiment of the present of invention are elaborated in conjunction with the accompanying drawings.
Brief description of drawings:
Fig. 1 is the circuit structure diagram of dual motor speed controller of the present invention.
Fig. 2 is the curve map of the loop response characteristic of dual motor speed controller.
Fig. 3 is the synoptic diagram of laser scanner.
Fig. 4 is a synoptic diagram of using scanner of the present invention.
10 motor control circuits
12 inputs
14 first motor control circuits
15 frequency control signals
19 input signal integrating circuit
20 difference on the frequency testing circuits
30,31,32 digital univibrators
22,42 amplifiers
24,44 motor drive circuits
60,70 motors
Consult Fig. 1, symbol 10 is dual motor speed control circuits of the speed of first motor 60 of expression control laser scanner and second motor 70.Can group go into example such as Fig. 3 of the handheld laser scanner of control circuit 10, hold the back explanation.
As shown in Figure 1, in order to control the speed of first and second motor respectively, control circuit 10 is supplied to and contains the frequency that is used and the input signal of duty factor key element.Dual motor speed control circuit 10, consist essentially of control first motor 60 speed feedback system the second motor control loop 14 and control the second motor control loop 16 of the feedback system of second motor, 70 speed.The primary circuit that constitutes the first motor control loop 14 comprises electric voltage frequency difference detecting circuit 20, amplifier/wave filter 22, motor drive circuit 24.The primary circuit that constitutes the second motor control loop 16 comprises integrating circuit 19, electric voltage frequency difference detecting circuit 40, amplifier/wave filter 42 and motor drive circuit 44.It is shared at the motor control loop 14 and 16 of dual motor speed control circuit 10 that N is cut apart counter 18.They note that not shown supply voltage of Fig. 1 and component parameters, because can be selected according to the needs of special-purpose.
Employed first motor 60 of dual motor speed controller and second motor all are d.c. motors, and speed and input driving voltage are in direct ratio.Employed motor respectively has a pair of coil among the embodiment.To the measurement that these motors carried out, the velocity variations of 1333 to 1900 per minute/volts (rpm/v) and the approximately gain of 75Hz/v have been shown.Approximately the gain of 75Hz/v is the frequency change of the every volt of expression motor control signal, fm.The frequency f m of motor control signal is 3 times of motor frequency.In order roughly to differentiate the motor response characteristic, carried out interim response and measured.The result of these mensuration has shown that each motor does the response of index with 1.25 seconds time constant.First motor 60 and second motor 70 respectively have a speed pickup (not being shown among the figure) that connects thereon, and these sensors provide the motor speed sensor signal of frequency f m1 and fm2 respectively.Frequency f m1 and fm2 are about 3 times of pairing motor running speed.This be because each winding of motor in motor whenever rotates a circle, alternately be communicated with three times due to (that is, per 60 degree).Motor speed sensor is the traditional design of the voltage of well-known detection winding own.When for example motor speed was 9000rpm, the motor speed sensor signal was output as 450Hz.
In order more easily to understand control circuit of the present invention, will be described to be used for the LS9000 scanning system, and will use the control circuit of the 80c196 of Intel Company microcontroller.But guidance of the present invention all can be used in combination with any dual motor scanning system, so be not limited to illustrated embodiment.
Illustrate among the embodiment that signal 12 is from the width modulation of the 80c196 of Intel Company microcontroller (PWM) the digit pulse string that pin produced.The PWM pin can produce the digit pulse string of certain frequency of the 11.8KHz of the 23.6KHz of motor full-speed operation among the corresponding embodiment or corresponding motor half-speed operation.The PWM pin can be selected the different duty factors to 255 arbitrarily.The selection of duty factor is reached by the pulse width modulation controlled register that single byte value is write Intel Company's microcontroller.These registers can receive the instruction of change from the single byte of the frequency of the digit pulse string of microcontroller PWM pin output or pulsewidth.The advantage of this machine is to need only minimal software, correspondingly can reduce the processing time of CPU.In case single byte value is write register, processor can continue to export identical train of impulses before new value is written into.This can shorten the processing time of CPU.Owing to can obtain most duty factor structures, microcontroller can produce most motor speed control modes.
In the first motor control ring road 14, the input signal 12 with controlled frequency fc and period T in is input into N and cuts apart counter 18.Among the explanation embodiment of the present invention, N equals 52.Cut apart counter 18 resulting frequency control signals 15 from 52 and have frequency f in, so the signal frequency that is present between input signal 12 and the frequency control signal 18 concerns as shown below:
fc＝52fin（Hz） （1）
1/Tin＝52fin （2）
1＝52finTin （3）
Hence one can see that, and the N that the frequency of frequency control signal 15 is cut apart counter 18 with N is that coefficient and input control signal 12 are proportional.The frequency f in of frequency control signal 15 and 60 runnings of first motor are gone up desired frequency and are equated.
As shown in Figure 1, frequency control signal 15 is input into electric voltage frequency difference detecting circuit 20.The function of the electric voltage frequency difference detecting circuit 20 of first motor control circuit is to judge frequency control signal 15 with frequency f in and the difference on the frequency of the operating frequency that first motor 60 that obtains from the first motor speed sensor signal 65 with frequency f m1 is present.The output signal 37 of corresponding this difference on the frequency is consequent.
For the running for electric voltage frequency difference detecting circuit 20 is described, need to describe in detail first and second digital univibrator 30 and 31.Numeral univibrator 30 is driven by frequency control signal 15.When the monostable many harmonic oscillators 30 in detail of numeral are triggered, it can provide one to be low level (0 volt) during 33 count pulses of incoming frequency fc, is reset to the reversed-phase output signal 35 of high level (5 volts) then during 19 count pulses of frequency input signal fc.Numeral univibrator 31 is driven by motor speed sensor signal 65, when being triggered, its can provide one during 33 count pulses of incoming frequency fc for high level (5 volts), then one be decided by first motor, 60 speed during in be the output signal of low level (0 volt). Numeral univibrator 30 and 31 timing are supplied with by input signal 12, and also available external clock substitutes.The output 35 of numeral univibrator and 36 is by addition resistor R 1 and R2 combination.Preferred embodiment is that R1 and R2 equate, total effectively input voltage Veff of filter amplifier 22 as shown below:
Veff＝ (19·Tin·5)/(1/fin) + (33·Tin·5)/(1/fml) （v）（4）
When using unequal resistance value, input voltage 35 and 36 needs weightings, and this moment, motor frequency can be offset from input control signal.
The normal formula of the mean value periodic voltage signal f(t that equation (4) is to use judgement to have period T) is tried to achieve:
In order to try to achieve the effective voltage of signal 35, substitution numerical value can be tried to achieve following formula:
Veff1＝ 1/(1/fin) ·19·Tin·5＝ (19·Tin·5)/(1/fin) （7）
Similarly, the effective voltage of signal calculated 36, then as shown below:
Veff2＝ (33·Tin·5)/(1/fml) （9）
Veff2＝ (33·Tin·5)/(1/fml) （10）
Please note that the Tin that is determined by input signal 12 is same to two signals.
Equation (7) and (10) are added up, can try to achieve total effective voltage Veff of signal 37 represented in the equation (4).Veff and predefined d. c. voltage signal 39 relatively relatively utilize the amplifier 22 of tool two input terminals and a lead-out terminal to reach.Fig. 1 has shown that signal 37 inputs to negative (-) terminal of amplifier 22 and d. c. voltage signal 39 inputs to just (+) terminal of amplifier 22.D. c. voltage signal 39 can utilize by resistor R 3 and bleeder circuit that R4 constituted and try to achieve.Among the illustrated embodiment, the value of resistor R 3 and R4 is the value that produces 2.5 volts d. c. voltage signal.The function of d. c. voltage signal 39 is actually as amplifier offset voltage.This value is fixed in first motor control circuit 14.Effective input voltage vin of pair amplifier 22 can be as shown in the formula expression:
Vin＝ (19·Tin·5)/(1/fin) -2.5+ (33·Tin·5)/(1/fml) -2.5（V）（11）
Effective input voltage vin of pair amplifier 22 is difference on the frequencies of the real-world operation speed of the speed of requirement of expression first motor and first motor.
First motor control circuit, 14 intrinsic control loop characteristics are when the Vin=0 volt, when just the characteristic output Vin of the control loop in feedback signal and input signal when coupling and point was 0 volt, the frequency f ml of motor one was just corresponding to the frequency f in of frequency control signal 15.This is with as follows shown in the mathematical equation:
Vin＝ (19·Tin·5)/(1/fin) -2.5+ (33·Tin·5)/(1/fml) -2.5
Vin＝19·Tin·5·fin+33·Tin·5·fml-5
During no frequency errors, the Vin=0 volt, therefore
fml＝ (5-19·Tin·5·fin)/(33·Tin·5)
fml＝ (1-19·Tin·fin)/(33·Tin)
Value " 1 " with the above-listed formula of formula (3) replacement then becomes following formula:
fml＝ (52·Tin·fin-19·Tin·fin)/(33·Tin) ＝ (33·Tin·fin)/(33·Tin) ＝fin
So in the time of Vin=0(V), the frequency of the frequency of first motor 60 and frequency control signal 15 equates.So first motor 60 can be with the desirable speed running that is set by frequency control signal 15.
In the illustrated embodiment, the voltage gain of amplifier 22 is fixed as 470, and this is its open-loop response to direct current signal basically.As shown in Figure 1, because feedback condenser 51 and resistor 52 make amplifier 22 also constitute a wave filter.Among the illustrated embodiment, this wave filter is to have 2 * 10
-3The lowpass structures of the one pole that Hz sets.Owing to dash cause saturated, require to have lower bandwidth in order to prevent amplifier 22 from 5 deep-sited pulses of the output signal 37 of electric voltage frequency difference detector 20.The gain of amplifier 22 and the selection of filtering characteristic need meet specific system requirements.
For gain with volt/Hz calculating voltage difference on the frequency detecting device 20, used the relation of above-mentioned equation (11), if fml=fin+fdiff, the fdiff here are the frequency of the signal 37 exported by electric voltage frequency difference detecting circuit 20 and expression by the represented frequency control signal of the output (being signal 35) of digital univibrator 30 with as the difference on the frequency from the motor speed sensor signal of the output (being signal 36) of digital univibrator 32.After the processing, the expression Vin formula as shown below:
The aforesaid equation of Vin=52Tin5fin+33Tin5fdiff-5 substitution (3), then
Vin＝33·Tin·5·fdiff
So the gain of electric voltage frequency difference detecting circuit 20 is:
Gain=(Vin)/(fdiff)=33Tin5(V/Hz) (12)
To frequency f c=23.6KHz(full-speed state) input signal, gain is 6.99mV/Hz.
As shown in Figure 1, the closure of the control loop on the first motor control ring road 14 is that the unity gain motor driver is connected between the input of the output of amplifier 22 and first motor 60.First frequency error correction signal 41 is the output signals from amplifier 22, and this signal 41 is that effective voltage Vin(by the input end of amplifier 22 is with reference to formula 11) decision, revise the running speed of first motor 60.When the frequency of the speed of first motor 60 and frequency control signal 15 was correct consistent, just during Vin=0, then frequency errors corrected signal 41 was about 8.0 volts direct current signal.If between the signal 15 and 65 some difference on the frequencies are arranged, then can produce the deviation of nominal value from then on.For example, when the running speed of first motor during less than first motor speed of the requirement that is set by frequency control signal 15, the Vin of amplifier 22 will become more than 0 volt.Correspondingly the nominal value output that also becomes than 8.0 volts of first frequency error correction signal 41 is big, so the speed of first motor 60 can correspondingly increase.When the first motor running speed during greater than first motor speed of the requirement that sets by frequency control signal 15, the Vin of amplifier 22 then becomes less than 0 volt, correspondingly 41 of frequency errors corrected signals are less than nominal value, and the first motor running speed can correspondingly reduce.Signal 41 itself is not suitable for driving first motor 60, thus first frequency error correction signal in order to revise the running speed of first motor 60, motor drive circuit 24 provides necessary driving.
The primary element of second motor control circuit 16 as shown in Figure 1, the element with first motor is identical basically, its dissimilarity is that the offset voltage of positive input terminal of amplifier 42 is adjustable.After relevant details will be illustrated in.
The same with the first motor control ring road 14, the second motor control ring road 16 of dual motor speed controller 10 utilizes the single input signal 12 with controlled frequency fc and period T in.This signal is sent to have to export than 52 of the frequency control signal 15 of importing the little 52 times frequency f in of controlled frequency fc cuts apart counter 18.Previous equations (1) is promptly represented this relation.Frequency control signal 15 is sent to the second electric voltage frequency difference detector 40.Electric voltage frequency difference detector 40 effect on the second motor control ring road 16 is to judge frequency control signal 15 with frequency f in and from the difference on the frequency of the present operating frequency of the second motor speed sensor signal, 66 resulting second motors with frequency f m2.The output signal 47 of corresponding this difference on the frequency also produces from aforesaid detector.In the present embodiment, it must be understood that digital univibrator 30 and frequency control signal 35 are shared for electric voltage frequency difference detector circuit 20 and 40.
If be necessary that frequency control signal also can be removed from circuit.And digital univibrator 32 is if utilize the internal clocking timing, and then second control circuit will only respond the duty factor information of input signal 12.In this case, keep one regularly as the input duty factor, second motor can be with the frequency change of input signal 12 change speed.
The running details that comprises the second electric voltage frequency difference detector 40 of digital univibrator 30 and 32 is with the same to the description of the first electric voltage frequency difference detector 20.Numeral univibrator 30 is driven by frequency control signal 15.When digital univibrator 30 is triggered, it can provide one to be that low level (0 volt) is the reversed-phase output signal 35 of high level (5 volts) during 19 count pulses at incoming frequency fc then in 33 count pulse phases of incoming frequency fc.Numeral univibrator 32 is to be driven by motor speed sensor signal 66, if be triggered, its can provide one during 33 count pulses of incoming frequency fc for high level (5 volts), be low level (0 volt) one during according to second motor speed then.Numeral univibrator 30 and 32 timing are to be provided by input signal 12.The output 35 of numeral univibrator and 38 combinations by addition resistor R 8 and R9 provide the signal that has with the represented similar total effective input voltage Veff of formula (4).
Veff＝ (19·Tin·5)/(1/fin) + (33·Tin·5)/(1/fm2) （V）（13）
Except the frequency correspondence of the frequency f m2 and second motor 70, the derivation of formula (13) is identical with formula (4).Effective input voltage vin of representing the velocity contrast of desired second motor speed and actual motor speed is that Veff and variable offset voltage signal 49 are relatively tried to achieve.This variable offset voltage signal is the output of signal integration circuit 19.As shown in Figure 1, input signal 12 is sent to input signal integrating circuit 19.The function of input signal integrating circuit 19 is that the duty factor with input signal 12 is converted to direct current signal 49.Because the duty factor of input signal 12 is variable, so corresponding direct current signal 49 also can change thereupon.Integrating circuit 19 is made up of R/C network and the operational amplifier 21 of resistor R 5, R6, R7, capacitor C1.The value of these elements is chosen as the requirement of compliance with system, and in addition, it is represented that the structure of integrating circuit 19 is not defined as Fig. 1.The function of output signal 49 is the offset voltages as amplifier 42.The value of this voltage is to be subjected to about the duty factor institute of input signal 12.This value Vset can followingly represent:
Vset＝5（1/2-K）（V）（14）
The K here is included in the function of DC voltage of the duty factor of input signal 12.Among the embodiment, the K value generally is any value in 0 to 0.3 scope preferably.This is corresponding to any value of the voltage range of signal 49 between 1.0 to 2.5 volts.For example, during K=0, then the Vset(signal 49) become 2.5 volts and the speed of second motor 70 and the speed of first motor will equate.During K=0.3, then the Vset(signal 49) become 1.0 volts of direct currents.The slow running speed of this corresponding second motor 70.
As previously mentioned, Veff can compare by d. c. voltage signal 49, and it relatively utilizes the amplifier 42 with two input terminals and an output to carry out.Fig. 1 is that expression signal 47 utilizes R9 and R8 to be input into amplifier 42 negative (-) terminals and d. c. voltage signal is input into just (+) terminal of amplifier 42.Effective input voltage vin of amplifier 42 can be as follows:
Vin＝ (19·Tin·5)/(1/fin) -Vset+ (33·Tin·5)/(1/fm2) -Vset（15）
Intrinsic control loop characteristic is when no frequency errors in second motor control circuit 16, and the Vin of amplifier 42 equals 0 volt.Therefore in equation (15), set the value that Vin=0 separates fm2, then draw:
fm2＝ (2·Vset-19·Tin·5·fin)/(33·Tin·5)
(2·（1/2-K）·5-19·Tin·5·fin)/(33·Tin·5)
fm2＝ (33-104K)/(1716Tin) （16）
Can be clear that very that from equation (16) frequency of second motor 70 and speed are decided by the K value relevant with the duty factor of input signal 12.The speed of second motor also is decided by Tin.Therefore reduce the frequency of input signal 12, the speed of first motor 60 and second motor 70 all can change pro rata.But the acting on the running speed that determines second motor 70 time influence be bigger of COEFFICIENT K.
The gain of amplifier 42 is fixed as 470 in the illustrated embodiment.Amplifier 42 also as the wave filter that has with the same lowpass structures of amplifier 22.In order to calculate the gain of the second electric voltage frequency difference detector 40, use the relation of aforementioned formula (11).If set fm2=fin+foffset+fdiff(this foffset be corresponding for the duty factor that is transfused to signal 12 about COEFFICIENT K to the effect of the speed of second motor 70), following result is then arranged:
Vin＝19·Tin·5·fin-2·（1/2-K）·5+33·Tin·5·（fin-foffset+fdiff）＝52·Tin·5·fin-5+2·k·5-33·Tin·5·foffset+33·Tin·5·fdiff＝2·k·5-33·Tin·5·foffset+33·Tin·5·fdiff
If the loop on the second motor control ring road 16 is satisfied, then become 2K5=33Tin5foffset.Therefore, Vin=33Tin5fdiff.So the gain of the 2nd electric voltage frequency difference detector 40 is:
Gain=33Tin5(V/Hz) (17)
In order to finish the control loop on the second motor control ring road 16, from amplifier 42 output second frequency error correction signals 53.This signal 53 is revised the running speed of second motor 70 by the effective voltage Vin decision (referring to equation 15) of the input terminal of amplifier 42.Because signal 53 itself is not suitable for driving second motor 70, so it is sent to motor drive circuit 44.Motor drive circuit 44 is unity gains and is used as isolation level.Be the running speed of second frequency error correction signal 53 corrections second motor, motor drive circuit 44 provides necessary driving.
Fig. 2 is to be unit with decibel (dB), represents the chart of the gain of the various elements that comprised in the dual motor speed control circuit 10 of illustrated embodiment to frequency characteristic.Applicable to the complete open-loop response curve of first motor and both control loops of second motor, in Fig. 2, represent with curve 100.
The amplifier frequency response curve is represented with curve 80 in Fig. 2.Curve 80 is corresponding to the amplifier 22 of dual motor speed control circuit 10 and 42 both responses.First and second electric voltage frequency difference detector 20 and 40 response in Fig. 2 with curve 85 expressions. Motor drive circuit 24 and 44 response in Fig. 2 with curve 90 expressions.First motor 60 and both open-loop responses of second motor 70 in Fig. 2 with curve 95 expressions.
The calculating of first and second motor control ring road 14 and total loop gain of 16, as shown below:
Gain * the amplifier gain of loop gain=electric voltage frequency difference detector * motor drive circuit gain * motor gain=6.99 * 16
-3(V/Hz) * 470 * 1 * 75(Hz/V)=246=47.8dB(supposes that the gain of average motor is 75Hz/V)
The represented gain-frequency characterisitic curve of Fig. 2 is only corresponding to those circuit components that uses in the embodiment of aforementioned dual motor speed control circuit 10.Value that Fig. 2 is represented and curve are according to employed motor characteristics and desirable control forms and change.
The present invention can use and resemble handheld laser scan type barcode reader unit shown in Figure 3 or resembling the indicating lamp type scanner of SL9000.Handheld type devices as shown in Figure 3 is to be recorded in United States Patent (USP) the 4th, 760, No. 248 form substantially.United States Patent (USP) the 4th, 387, also can be used on the formation handheld laser scan type barcode reader unit or SL9000 indicating lamp type scanner shown in Figure 4 as shown in Figure 3 No. 297, or 4,409, No. 470 device.These United States Patent (USP)s are quoted in this article for the 4th, 760, No. 248, the 4th, 387, No. 297 or the 4th, 409, No. 470 as a reference.Outgoing beam 151 normally utilizes laser diode to produce in reader 200, and directive is apart from the bar code symbol of positive several inches of reader unit.Outgoing beam 151 is that the user locatees this handheld unit so that this scanning patter mould is crossed symbol to be read with fixing linear graph scanning.The photoresponse device 146 that is read in the device from the reflection ray 152 of symbol detects, and produces processed serial electric signal to discern bar code.Reader unit 200 is tool pistol-like devices, has pistol grip handle 153 and trigger 154.When symbol that aligning is desired to be read, the user can start light beam 151 and testing circuit by cocking, can extend the life of a cell when reader is the self-powered formula like this.Light plastic shell 155 built-in LASER Light Source, detecting device 146, optical module and signal processing circuit and CPU140 and battery 162, the light inlet window in the front of shell 155 can make outgoing beam 151 penetrate and the reflected light 152 of incident can be entered.The design of reader 200 is to allow the user retouch accurate symbol in the position of leaving bar code symbol one determining deviation, that is, do not contact also and need not cross symbol by traversing reader, and typically, such handheld reader is specific works in several inches scope.
As shown in Figure 3, use a suitable lens 157(or a poly-lens system) scanning light beam collimation is made its directive bar code symbol and focuses it on the suitable reference surface, for focus reflection light 152, also can utilize same lens 157.Light source 158 as laser diode is arranged at the position that the light of its generation can import the optical axis of lens 157 by the silver-plated mirror of a part and other lens or necessary light beam reshaping structure and a vibrating mirror 159, this vibrating mirror 159 is arranged on the scanning motor 160, and this scanning motor is activated when cocking.When light source 158 produce be invisible light the time, can in optical system, comprise retouch quasi-optical, utilize once more here a part of silvered mirror with this light beam import with the coaxial light path of lens 157 in.In case of necessity, retouch the visible light spot that quasi-optical generation one scans as laser beam.The user utilized this visible light that reading unit is retouched accurate symbol before cocking 154.
Though abovely the present invention has been described with regard to relevant linearity or single line bar code, but the present invention is not limited to this embodiment, also can be applied in more complicated scanning patter and multilayer or two dimension bar code is as code 49(Code49) or with its similar sign list notation.Method of the present invention also can be utilized on the purposes of various computer visions or optical identification.
In various embodiments, each element of scanner can be mounted in the very small-sized shell so that scanner can be used as single printed circuit board (PCB) or integration module and assembles out.Such module can be utilized as the laser scanning element that various multi-form data-acquisition systems are used, and has interchangeability.For example this module can interchangeablely be used for the following table top scanner of erecting frame or table top that a hand-held type scanner or is installed on a flexing arm or stretches out table surface, or is used as the subassembly or the accessory of a data-acquisition system.
This module preferably includes laser instrument/optical sub-assembly of being installed on the bearing, as the scanning element and the photodetector of revolution or the catoptron that moves back and forth.Control that is connected with these parts or data line can be connected on the electrical connector that is arranged at this module edge or outside surface so that this module can be electrically connected to one with connecting on the web member that other parts of data-acquisition system are connected.
A module can have specific scanning or decoding characteristic, but for example at the workability of certain operating distance, but or the specific symbol table notation or the workability of printing density.These characteristics can utilize the manual setting of the gauge tap that links to each other with module to decide.By using above-mentioned simple electrical connector, the user can utilize and change the above-mentioned module in the data-acquisition system and make data-acquisition system be applicable to the article of scan different types or make system be applicable to different purposes.
Aforesaid scan module also can use in the data-acquisition system of appearance certainly that comprises as one or more parts of keyboard, display, data storage, application software and database.Such data-acquisition system also can comprise a communication interface make this system can by a modulator-demodular unit or isdn interface or by one from movable termination to one fixedly receiver the low-power radio frequency radiowave and with other parts or the telephone-switching network communication of a Local Area Network.
Should be appreciated that aforesaid each feature or two or more combination of features, can be effectively applied to scanner and the barcode reader different with aforesaid scanner form.
As above illustrated, utilize the present invention can reduce the cost of motor speed control, the device that produces most figures is provided.
Claims (4)
1, a kind of scanister that scans a target repeatedly has a laser generator, two scanning motors and is used for the difference dual motor speed control circuit of gated sweep motor speed independently, and this dual motor speed control circuit comprises:
One is used to utilize the frequency information that obtains from the input signal of the described dual motor speed control circuit of an input to control first motor control circuit of the speed of first motor; And
One is used to utilize the control circuit of duty factor information Control second motor speed that obtains from described input signal.
2, a kind of scanister that scans a target repeatedly has a laser generator, two scanning motors and is used for controlling independently respectively the dual motor speed control circuit of described scanning motor speed, and this dual motor speed control circuit comprises:
One is used to produce first input circuit device that has with the frequency control signal of the proportional frequency of frequency of the input signal of the described control circuit of an input;
One is used to control the first control circuit of first motor speed, the speed of this first motor directly be subjected to described frequency control signal frequency about;
One is used to produce second input circuit device that is subjected to the variable DC voltage signal about described input signal duty factor; And
One is used to control the second control circuit of second motor speed, the speed of this second motor be subjected to described frequency control signal and described variable DC voltage signal about.
3, a kind of method with scanister multiple scanning one target of a laser-beam generating apparatus and two scanning motors of utilizing, this method may further comprise the steps:
A, provide an input signal with frequency and duty factor information;
The frequency information that b, utilization obtain from described input signal is controlled the speed of first motor;
C, utilize the speed of duty factor information Control second motor that obtains from described input signal.
4, a kind of method with laser scanning device multiple scanning one target of a laser-beam generating apparatus and two scanning motors of utilizing comprises:
The frequency control signal that a, generation obtain from an input signal;
The speed of b, control first motor directly is subjected to about the frequency of described frequency control signal the speed of this first motor;
C, produce a variable DC voltage signal that is subjected to about the duty factor of described input signal;
The speed of d, control second motor, make the speed of this second motor be subjected to the frequency of described frequency control signal and described variable DC voltage signal about.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN92112396A CN1045830C (en) | 1992-10-28 | 1992-10-28 | A dual motor speed controller |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN92112396A CN1045830C (en) | 1992-10-28 | 1992-10-28 | A dual motor speed controller |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1086330A true CN1086330A (en) | 1994-05-04 |
| CN1045830C CN1045830C (en) | 1999-10-20 |
Family
ID=4945927
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN92112396A Expired - Fee Related CN1045830C (en) | 1992-10-28 | 1992-10-28 | A dual motor speed controller |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1045830C (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109742981A (en) * | 2018-12-21 | 2019-05-10 | 西南交通大学 | Two-dimensional scanning electric system and the method for scanning |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5023818A (en) * | 1989-09-21 | 1991-06-11 | Ncr Corporation | Laser scanner safety apparatus and method |
| US5003164A (en) * | 1989-10-30 | 1991-03-26 | Symbol Technologies Inc. | Portable laser scanning system and scanning methods having a motor amplitude regulator circuit |
| US5115121A (en) * | 1990-01-05 | 1992-05-19 | Control Module Inc. | Variable-sweep bar code reader |
-
1992
- 1992-10-28 CN CN92112396A patent/CN1045830C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109742981A (en) * | 2018-12-21 | 2019-05-10 | 西南交通大学 | Two-dimensional scanning electric system and the method for scanning |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1045830C (en) | 1999-10-20 |
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