DD228058A1 - PHASE SYNCHRONIZATION DEVICE FOR STEPPER MOTORIZED MODULATION DEVICES - Google Patents

Abstract

The invention relates to a phase synchronization device for step-driven modulation devices, in particular for multi-channel Spektralanalysengeraete. The aim of the invention is to reduce the technical-oeconomic effort and the adjustment effort and the increase in reliability. The object is to provide a phase synchronization device for stepper-controlled modulation devices without any mechanical adjustment elements. According to the invention, a synchronization signal is generated via a sensor fixedly arranged on the modulation device, which synchronizes the pulse shortening a counting process of an adjustable time-delayed pulse train directly from the cycle of the control frequency of the step drive for the modulation device. Evaluation signals for the evaluation stages of the electrical signal corresponding to the optical signal are obtained from the counting process in a logical connection stage. Fig. 1

Description

Title of the invention;

Phase synchronization device for stepper-controlled modulation devices

Field of application of the invention:

The invention relates to a phase synchronization device for stepper-controlled modulation devices, in particular for multi-beam spectral analysis devices. The invention can be used anywhere where optical beam paths are mechanically / optically modulated and synchronous and in-phase electrical evaluation signals must be obtained in order to process the electrical measurement signals generated by the Other special applications include photometers, calorimeters and others Physic-optical analyzers ·

Characteristic of the known technical solutions: The drive of optical modulation devices for analysis measuring devices is generally carried out with a synchronous motor (eg DD-PS 65468).

The modulation devices, which consist of rotating mirrors and / or diaphragms, generate eg with a two-beam photometer at least two signals to be evaluated ( ⁿ measuring ^M and "reference").

For devices with microcomputer for evaluation and control, it is expedient to increase the measurement accuracy to measure within a modulation period, the zero signal with.

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After amplification in an AC amplifier, the lost mean value of the time-nested measuring, reference and zero signals is restored by the so-called clamping. Further evaluation signals for the electrical evaluation of the optical signal are required for the integrator enable, integrator cancellation, AD converter start and identification of the Measuring, reference and zero signals · These evaluation signals are known to be removed by several sensors (eg · optocouplers) from the modulation device extended with control discs or tracks · The sensors must be very precisely adjusted mechanically and have corresponding position-variable attachment and adjustment, the a relatively high technical and economic effort conditional · Since the adjustment is done while the device is running, may not be interrupted during the adjustment neither the optical beam path, nor Bremdlicht get into the beam path · Under this Vorauss An exact adjustment is associated with a high expenditure of time and with a grain-oriented handling technology. Moreover, the many mechanical adjustment elements limit the reliability of the phase synchronization. It is also known (for example, DE-OS 3 202 807) to use a stepper motor in a spectral analysis device for interrupting light.

The stepping motor driven light beam interrupter generates a pulsating light beam · It applies a device responsive to this light beam for generating a phase synchronous demodulation signal · A high frequency clock signal is lowered by a fire device before it reaches the stepping motor · To generate the demodulation signal, the frequency divider of FIG same high-frequency clock signal, which is divided by a divider to the extent that the same Irequenz as that of the light beam is achieved ·

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Starting from the optical signal of the analyzer, the demodulation signal with the scanning signal (S optical measuring signal) is phase-synchronized via the detector and a connected thereto Uulliniendetektor. The detector is therefore simultaneously used to generate the scanning signal, i. Signal after passing through the optically active sample, and used to generate the demodulation signal.

At higher absorbances of the optical sample, this demodulation is degraded by the noise or fails completely. The disclosed solution is also applicable only to a single-jet device.

Object of the invention:

The aim of the invention is to reduce the technical and economic effort and the adjustment effort and increase the reliability ·

Explanation of the essence of the invention:

The invention has for its object to provide a simple and quickly adjustable phase synchronization device for stepper-controlled modulation devices, in particular for multi-beam spectral analysis, without any mechanical adjustment elements.

According to the invention, this object is achieved in a phase synchronization device for stepper-controlled modulation devices, in particular for multi-beam spectral analysis with a controlled by a stepper drive and mirror and / or aperture modulation means for optical timing and preferably switching the intended measurement evaluation light beam in measuring and reference channels, with a from Clock for the stepper-controlled counter and with an arrangement for generating evaluation signals for "clamp / erase", for "analog-to-digital conversion" and for

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"Identification of the optical signals" applied to evaluation stages for the analog and digital processing ung the electrical signals generated from the optical signals, achieved in that the input for the control frequency of the stepper drive via a preferably designed as a monostable multivibrator adjustable in the delay time Zeitverz 'dgerungsstufe and via a subsequent pulse shortening stage with the count input of the counter is connected to that at the modulation means a preferably designed as an optoelectronic reflex coupler stationary sensor with subsequent threshold level for generating a phase-independent with the optical signal and its signal information independent synchronization signal for Bücksetzung of the counter is arranged via a pulse shortening stage and that connected to the counting and carry outputs of the counter, a logic operation stage for generating the evaluation signals i It is advantageous if the logic operation stage is composed of reset and triggered flip-flops set by the count and carry outputs of the counter for generating the "clamp / erase" and "analog-to-digital conversion" evaluation signals and from a counter for generating the evaluation signals for "identification of the optical signal" is present at the counting input of one of the evaluation signals formed by the bistable multivibrators and at the resetting reset the pulse-shortened synchronization signal. According to the invention, a synchronization signal is generated independently of the signal information of the optical analysis signal via a sensor arranged at the modulation device. With the aid of this synchronization signal, which is unimpaired even at higher absorptions of the optical analysis sample, all evaluation signals for controlling evaluation stages are generated in a purely electrical manner as well as for signal identification (in particular for multi-beam analysis devices),

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which previously had to be adjusted by complex mechanical adjustment, generated by logical link with an adjustable delay and pulse shortened pulse train derived directly from the control frequency for the stepper drive of the modulation device · Hur via a sensor arranged on the modulation device, not for phase synchronization as adjustment is used, all evaluation signals to control the evaluation stages for the evaluation of the optical analysis signal equivalent electrical measurement signal obtained via logic operations «The adjustment of the entire synchronization process in the generation of said Auswatesignale is by electrical adjustment of only one Justierelementes (controller designed as a monostable multivibrator Time delay stage) very aufwandgering and with high reliability possible · The logical link to form the individual evaluation signals is te very diverse reali- It is very expedient, in particular for reasons of complexity, to set, reset and trigger bistable flip-flops with the counter and carry outputs of the counter synchronized by the pulse-shortened synchronization signal, at the outputs of which first the evaluation signals for "clamping / clearing" One of these evaluation signals then clocks another counter, which is reset in each case by the pulse-shortened synchronization signal. At the output of this counter, the evaluation signals for the "identification of the optical signal" are produced.

The device according to the invention is not bound to specific constructional embodiments of the modulation device, since it does not have to have any special constructive elements, such as additional control disks or tracks, for the phase synchronization. The sensor to be stationarily arranged at the modulation device is opto-couplers on the anyway

for the modulation existing mirror or the aperture aligned ·

Embodiment;

The invention will be explained in more detail below with reference to an exemplary embodiment illustrated in the drawing, in which: FIG. 1 shows a device according to the invention for generating and adjusting the evaluation signals

Pig · 2: evaluation stages for processing the electrical measurement signals equivalent to the optical analysis signals Pig. 3ϊ Pulse Diagrams for Phase Synchronization Embodiment relates to a dual-beam spectrometer for the UV-VIS region with a modulation frequency of, say, 40 Hz.

The modulation device consists of a two-part rotating modulation mirror with an aperture located on the same shaft.

The optical beam path is switched over and interrupted with this mirror shutter system. The optical analog signal thus generated contains the analog signals reference R, measuring M and envelope separated by time in each modulation period. H.

A mechanical device specifies the position of the modulation mirror and diaphragm for the defined excited but stationary stepping motor and, on the other hand, the position of the reflector coupler (sensor) to the optical beam path during group assembly. The stepping motor has a step angle of 6 ° to a modulation period of 180 ° become

s 30 steps needed.

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By the computer-controlled Eochlauf of the stepper motor after switching on the device eliminates the previously necessary start-up clutch drive with synchronous motor · With the clock frequency of 1.2 kHz, the modulation frequency 40 Ez is generated ·

FIG. 1 shows the device according to the invention for generating and adjusting the evaluation signals for the phase synchronization. The above-mentioned modulation device is indicated by the principle · For reasons of clarity, however, only one modulation mirror 3 is shown (the representation of a diaphragm arranged on the same drive shaft has been omitted for the sake of simplicity)

A clock frequency T ₃ with the frequency of 1.2 kHz controls a stepper drive, consisting of a drive unit 1 and a stepper motor 2. This drives the modulation mirror 3 (and an aperture, not shown). The modulation device is used for optical timing and switching of a light beam, not shown in MeB and reference channel and to form the null signal · At the modulation mirror 3 is fixedly arranged an optoelectronic Heflexkoppler 4, the optical beam path is switched by the movement of the modulation mirror 3. The voltage supply of the reflex coupler 4 is indicated by two unspecified resistors. Via a threshold stage 5 and an inverter 6, the eflex coupler 4 generates a synchronization signal S whose time profile is shown relative to the optical signal of the analyzer (FIG. 3s) i & FIG. 3b.

The analog signal (optical signal), the synchronization signal S and the clock frequency T_ (FIG. 3c) have a

fixed phase assignment. With a pulse shortening stage 7, a signal 8 for clearing (resetting) of a counter 13 is generated from the LH edge of the synchronization signal S, which counts decadically in the example.

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From the clock frequency T _g , a monoflop 11 is also triggered, which generates the pulses as a result of its holding time t _fl according to FIG. 3 d, wherein the hold time t _{H is} determined by a resistor 9 and a capacitor 10. so that the holding time t is electrically adjustable. The monoflop 11 controls via a pulse shortening stage 12, the count input of the counter 13 with counts 0? _z (Pig · 3e). To the count and carry outputs Q.sub.1,..., v.sub.n of ^the counter 13, there is connected a logical connection stage consisting of two D-type flip-flops 14, 15 and one of two bit counters 16.

The D-flip-flop 14 provides the evaluation signal "clamp / clear" (Pig * 3i). It arises because the carry signal Ü _v (FIG. 3h) of the counter 13 sets the D flip-flop 14 and the following one IH-plank of the output signal Q ^ of the counter 13 (Pig · 3f) the D-Elip-Plop 14 triggers · The evaluation signal "terminals / clear" (Pig · 3i) goes to L-potential, because at the D-input of the D -Plip-Plops 14 L potential is applied.

The D-Plip-Plop 15 supplies the evaluation signal for "analog-to-digital conversion"("AD.Start"). It arises from the LH plank of the output signal Q ^ of the counter 13 at D = H, ie from the transition from count state "8" to count state "9" of the counter 13 · The carry signal Ü _v "(Pig.3h) of the counter 13 sets via the E input of the D-Plip-Plops 15 whose output signal again L-Poten tial · This output signal (evaluation signal "analog-digital conversion") simultaneously controls the count input of the 2-bit counter 16, each by the The first subsequent output signal of the D-Plip-Plop 15 switches the 2-bit counter 16 to count state "1." This count state indicates the reference signal (Pig · 3a) of the analog signal D-Plip-Plops 15 switch the 2-bit counter to count states "2" and "3 ⁿ -

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Counting state "2" indicates the measured value and counting state "3" indicates the zero value of the analogue signal (FIG. 3a). _

In this way, by logically combining the evaluation signal "analog-to-digital conversion" ("AD start") and the pulse-shortened synchronization signal S, the evaluation signals for "identification of the optical signal", fig. 2 shows in a greatly simplified manner (schematic illustration) the analogue amplifier for the electrical measurement processing of the analytical measuring device.

A photomultiplier 17 supplies the analog signal to an amplifier 18. A capacitor 19 separates the DC component of the analog signal. A switch 20 clamps, when the photomultiplier 17 is darkened by the optical shutter, not shown, the potential at the input of an amplifier 21 to zero YoIt. The switch 20 is controlled, as indicated, by the evaluation signal for "clamping / clearing". An integrator consisting of resistor 22, amplifier 23 and capacitor 24 successively integrates the signals H, M, N of the analog signal (FIG. 3k). Between the signals E, M, N, said integrator is cleared by means of a switch 25. For this purpose, in turn, as indicated, the evaluation signal for "terminals / delete" used.

An AD converter 26 is started by the evaluation signal for "analog-to-digital conversion" ("AD start") (FIG. 3d) and successively digitizes the analog-integrated signals R, M, N. The AD start at Η- For example, the potential of the synchronization signal S uniquely identifies the digitized value of the signal H. In the next evaluation signals for the "AD start", the digitized values of the signals M and N of the analog signal ensue.

Instead of the AD converter, a voltage-to-frequency converter can be used by a slight circuit change.

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Ir is released during the duration of the signals E, M and N. · A subsequent microcomputer detects the respective Eapulszahlen.

1 and 3 show that with a corresponding selection of the signal length of R, M and N in angular degrees and the step angle of the stepping motor of the effort for the generation of the control signals (Fig. 1) is extremely low ·

In FIG. 3, in order to better illustrate the functional sequence, the signal waveforms already mentioned are shown diagrammatically in their temporal dependence.

Fig. 3J Time course of the signals, based on the rotation angle of the mirror aperture group. 180 ° correspond to the period of

^{T s} Ί = ΤΟΠΕ ^{a 25 ms} *

Fig. 3a: Course of the analog signal, as it is generated in the photometer with the mirror aperture group. It contains the signals reference R, measurement M, zero N in a time-shared manner. For ease of explanation, the phase shift of the electronic amplifier is set equal to zero. Thus, Fig. 3a represents both the optical and the electrical analog signal.

Fig. 3b: Synchronization signal S, generated by the reflection coupler 4 by means of modulation mirror 3 »which switches the optical beam path · Are used, the LH edge for deleting the counter 13 and the Η signal to identify the reference signal R.

Fig. 3c: clock frequency T _s from the microcomputer for stepper drive.

Fig. 3d: output signal Q of the monostable multivibrator 11. LH edge is derived from T _s ; Holding time t _H by resistor 9 3 · can be set · Fig. 3e: clock signal T _z for counter 13, derived from HL edge of Q of the monostable multivibrator 11th

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Fig. 3f g: Aasgangssignale Q ^ and Q ^ of the counter thirteenth

Fig. 3h: carry forward Ü _{y of} the counter 13 · Fig · 3i: clamping, clear signal K / L for the analog amplifier to Pig · 2, generated from Ü _y and LH edge of Q _{A of} the counter 13 ·

FIG. 3d: AD start AD-St for the AD converter in FIG. 2, FIG.

generated by LH edge of Q ^ at Q _D = H and Ü _v

of the counter 13.

3k: signal at the integrator output or at the input of the AD converter. At the time of the LH

Flanks of AD-St are the integrated values

of E, M and N to be digitized.

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Claims (2)

claims 1 · Phase synchronization device for stepper-controlled modulation devices, in particular for multi-beam Spektralanalysengerate with a controlled by a stepper drive and mirror and / or aperture containing modulation means for optical timing and preferably switching the intended measurement evaluation light beam in measuring and Eeferenzkanäle, with a clock for the stepper drive Controlled counter and with an arrangement for generating evaluation signals for "clamp / erase", for "analog-to-digital conversion" and "identification of the optical signals", the evaluation stages for the analog and digital processing of the electrical signals generated from the optical signals Abut measuring signals, characterized in that the input for the control frequency of the stepper drive via a preferably designed as a monostable multivibrator in the delay time adjustable time delay stage and a subsequent Impulsverkür tion stage with the counting input of the counter is connected to .. on the modulation device preferably designed as an optoelectronic reflex coupler stationary sensor with subsequent threshold level for generating a phase-independent with the optical signal and its signal information independent synchronization signal for resetting the counter via a pulse shortening stage and that a logical combination stage for generating the evaluation signals is connected to the counting and carry outputs of the counter. 2. phase synchronization device according to claim 1, characterized in that the logic operation stage set by the count and carry outputs of the counter, reset and triggered bistable flip-flops for generating the evaluation signals 4714 for the "clamping / erasing" and for the "analog-digital conversion" and from a counter for generating the evaluation signals for "identification of the optical signal", at the counting input of one of the evaluation signals formed by the bistable multivibrators and at its Bücksetzeingang the pulse-shortened synchronization signal applied · HereZLt Ξ SeNe ^ 4714