RU2000023C1 - Optical contactless level gauge - Google Patents

Abstract

Usage: in the control technique, in particular in optical non-contact level gauges, Summary of the invention: -the device contains a power source 1, a light emitter 2, a light chopper 3, a photosensor 4, two DC amplifiers 5 and 10, a synchronous detector 6, telephoto lens 7, at least two receiving photodiodes 8, thermostat 9, indicator 11.8 10-6-11. 1-2. Receiving photodiodes are turned on in parallel and installed in a thermostat. The light emitter, the interruptor of the light flux, the photo-sensor, the sync signal and the telephoto lens are arranged in series. 4 ill.

Description

The invention relates to measuring technique, primarily for measuring the level of glass melt and glass melting units. In addition, the invention can be used to measure the levels of other liquids and melts having a mirror surface and reflectance in the visible range of optical radiation.

The claimed invention is directed to solving a technical problem, which consists in simplifying the design and circuitry of a prototype level gauge, eliminating background noise on the measurement results due to the temperature stabilization of the receiving photodiodes and changing the circuit of their inclusion, as well as by choosing a certain class emitters of a light stream. The use in the circuit of a level meter of a synchronous detector controlled by clock pulses coming from an additional photosensor with a frequency

a follow equal to the interruption frequency of the light flux provides a second level of filtering interference caused by the radiation of molten glass.

The invention is characterized by a combination of features, including a power source, a light emitter, a light output chopper, a telephoto lens, at least two receiving photodiodes, a DC amplifier and an indicator. Distinctive essential features are: the thermostat, in which the receiving photodiodes are placed, an additional sync signal photosensor installed between the light output chopper and the lens, a synchronous detector connected between the constant current amplifier and the indicator, while the receiving photodiodes are connected in parallel with each other, and a blue photosensor - the clock pulse is connected through an additional constant amplifier (L

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ke to the second input of the synchronous detector, and a halogen lamp, for example, type KGM-24-150, was used about the quality of the light emitter.

The technical result from the implementation of the invention consists in eliminating the influence of background noise on the accuracy of measuring the level of glass melt and increasing the reliability of the level gauge. In addition, simplification of the measuring circuit of the device and reduction of the effect of vibrations and prominences are achieved by using a convergent conical beam formed by a telephoto lens. An angled cone beam forms a spot of light in the form of an ellipse on the surface of the glass melt, the length of which along the major axis of the ellipse depends on the angle of incidence of the beam. Therefore, the surface waves of the glass melt practically do not affect the fluctuation of the light spot in the area of the working plane of the receiving photodiodes.

In FIG. 1 shows a general block diagram of a level gauge: FIG. 2 - equivalent circuit of a DC amplifier; in FIG. 3 is a functional diagram of a synchronous detector: in FIG. 4 - time diagrams of the operation of a synchronous detector.

The level gauge contains a power source 1, a light emitter 2, a light chopper 3, a sync signal photosensor 4 connected via an additional DC amplifier 5 to the second input of a synchronous detector 6, a telephoto lens 7, receiving photodiodes 8 located in the thermostat 9 and connected among themselves counter-parallel, a DC amplifier 10 and an indicator 11, which can be used as a pointer or digital device.

The level gauge works as follows.

From a stabilized power source 1, the supply voltage is supplied to the light emitter 2, which is a KGM-24-150 type halogen lamp, which creates a continuous diverging light flux. The luminous flux is interrupted by a mechanical chopper 3 with a frequency of 30 Hz.

The divergent pulsed luminous flux obtained in such a way is collected by a telephoto lens 7 (MTO-1000) and is directed to the surface of the glass melt at an angle equal to approximately 10 angles. An elliptical trace is formed on the mirror surface of the glass melt having an area sufficient to smooth out surface disturbances of the glass melt.

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glass fiber, the beam of light is focused by the lens 7 onto the surface of the receiving photodiodes 8, which are located close to each other and whose axes are in a vertical plane. The working surface of the photodiodes is oriented perpendicular to the incident beam. Any change in the level of the molten glass Ah causes a linearly related movement of the focused beam AI. Moreover, D 2 Ahcosa, where a. - the angle of the optical axis to the surface of the glass. At the nominal level (Дп 0), the light spot formed by the reflected beam creates the same illumination of both receiving photodiodes 0 and the output signal with a DC amplifier is equal to zero. When the light spot is shifted upward (the level of the glass melt rises), the useful pulse signal has a positive polarity, and its amplitude changes in proportion to Дп. When the beam is shifted down, the polarity of the pulses will be negative. The dependence of the amplitude of the pulse-SOW on Ah is thus retained.

The thermostat 9 stabilizes the temperature surrounding the photodiodes within the range of 37 ° C ± 2 ° C, thereby eliminating the influence of the temperature drift of the photocurrents on the measurement accuracy.

Counter-parallel connection of the receiving photodiodes 8 along with the use of the galvanometric mode, in which they operate as current generators (Fig. 2), allows for the first level of compensation of the background illumination. The uniform illumination of the receiving photodiodes creates equal and opposite currents 11 and 12. The combined effect of which does not cause a change in the output voltage from the amplifier 10. Such a switching circuit of the receiving photodiodes also increases the dynamic range of the DC amplifier.

The second level of backlight compensation, which is necessary for uneven illumination of the receiving photodiodes with backlight, is carried out in synchronous detector 6 (Fig. 3). Sync pulses with a duty cycle of 5-6, carrying information about the moments of occurrence (q, gz) and loss (t2, t) of the useful signal (Fig. 4), switch electronic key K. At time intervals (0-t, t2- t3. t4), when there are no clock pulses, the key K is closed and the isolation capacitor C glows the information about the level of background illumination 1) f. In the presence of clock pulses coming from the photo sensor 4 (mm)) premium

ti-tj. t3-ti), the key K is open and the signal passes to the output of the detector 6, while the component Of which is contained in it is compensated, and only a useful pulse signal is supplied to the indicator 11.

The implementation of the essential features of the invention ensures the achievement of a technical result consisting in measuring the level of molten glass in the melting units within ± 2.5 mm with a reduced error of not more than ± 2%, which is twice as much as the similar values of the prototype.

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The level gauge has increased reliability in operation, as well as simplicity of design and low cost due to the exclusion of expensive laser systems and the use of standard domestic units, especially halogen sources. In addition, due to the use of a protective circuit for receiving photodiodes from the influence of external temperature factors, the range of stable operation of the level gauge has been expanded, which is especially important when measuring the level of high-temperature melts.

Claims (1)

SUMMARY OF THE INVENTION Optical non-contact gauge for molten glass melt, -containing power source connected to a light emitter. sequentially installed with a light flux interrupter and a long-focus object, at least two receiving photodiodes, a direct current amplifier and an indicator, which are different. that, a synchro-photo sensor installed between the light chopper and the telephoto lens is introduced into it, synchronous a detector connected between the first DC amplifier and the indicator, a second DC amplifier connected to the second input of the synchronous detector, and a thermostat, while the anode and cathode of the clock sensor are connected respectively to the first and second inputs of the second DC amplifier, receiving photodiodes installed in a thermostat, turned on in parallel and connected to the inputs of the first constant current amplifier, and the light emitter is made in the form of a halogen lamp. Figure 1