RU2297605C1 - Mechanical motion transducer - Google Patents

Abstract

FIELD: measuring technique.

SUBSTANCE: mechanical motion transducer can be used for measurement of linear and angular motions of object to be observed. Mechanical motion transducer has two rectilinear or angular scales in form of first and second rows of straps divided by common conducting bus. Rows of straps are shifted one relatively another for one strap. Any strap has signal output. Straps are made of material, which demonstrates hysteretic dependence of resistance on dependence, for example, of vanadium dioxide. Film heater and thermocouple are disposed on other side of substrate. Width of radiation light band equals to vertical size of double scale made of thermo-sensitive straps.

EFFECT: double improvement in resolution angular or linear motion transducer; termination of ambiguity of indications of readings.

2 cl, 6 dwg

Description

The invention relates to methods for measuring non-electric quantities and can be used to measure linear and angular displacements of the object of observation.

Known sensors of linear and angular displacements [1]. Depending on the range of measured values and design requirements, they can be built on the basis of rheostatic, capacitive, inductive, tensoresistive, piezoelectric transducers.

These sensors are used to measure linear displacements in the range of 0.1-5 mm with an accuracy of 0.1 mm and angular displacements in the range of 1-45 ° with an accuracy of 10-0.5 ang. min

When solving the problem of measuring significant linear (5-50 mm) and angular (1-360 °) movements with an accuracy corresponding to 0.05 mm and 30-1 angles. c linear and angular displacement sensors are used, which include a substrate made of a transparent or opaque material coated with a large number of opaque or absorbing strips that are scanned by a moving beam of a source fixed to the object of observation and the light detector, from the output of which the pulses are fed to the reverse counter [2].

The disadvantage of the sensors is the need to return the substrate to its initial position in order to be able to measure the movement of another object of observation. The elimination of the ambiguity in the indication of the readings of these sensors is achieved by including two converting elements on each strip, while the leading element is located somewhat ahead of the slave. These elements, together with an external control circuit, determine the actual output of the sensor, while complicating the design, in addition, the resolution of the sensor decreases.

The objective of the invention is to double the resolution of the sensor of angular or linear displacements, eliminating the ambiguity of displaying readings of these sensors.

The problem is achieved in that the displacement sensor containing a light source mounted on the object of observation, a substrate with a rectilinear or angular scale formed by absorbing strips located on the substrate at a distance from each other equal to the size of the strip, the strips on the substrate are arranged to form the first and the second row of strips separated by a common conductive bus, and the strips of the first row are offset from the strips of the second row by one strip, the strips are made of material with a hysteresis temperature is dependent on resistance and each strip is equipped with a signal output, film heater and thermocouple are placed on the other side of the substrate, heat-sensitive strips are connected to an analog switch included in the interface of the measuring system.

The proposed sensor is illustrated by the drawings shown in figures 1 to 6.

Figure 1 shows the temperature dependence of the specific surface resistance of the VO ₂ film with a thickness of 100 nm. As you can see the width of the loop of the temperature hysteresis film VO ₂ is equal to 18 ° C, while the jump in conductivity is 20: 1.

By thermostating the VO ₂ film at a level of 70 ° C, the internal memory mode is implemented. The power density of the radiation source, which provides heating of the VO ₂ film by 2-3 ° C relative to the temperature of thermostating, is (2-3) 10 ^-2 W / cm. The semiconductor-metal phase transition (FPPM) in the VO ₂ film has a hysteretic character and occurs in the range 44–85 ° С. The width of the hysteresis loop is 15-18 ° C with a VO ₂ film thickness in the range of 115-80 nm. Film heater heats VO ₂ film to a temperature equal to the middle of the hysteresis loop. The presence of the internal memory of the heat-sensitive layer of the thermal sensor based on the VO ₂ film provides absolute fixation of the object under observation and greatly simplifies the control circuit.

Figure 2 shows the design of the linear displacement sensor. A radiation source 2 is installed at the object of observation 1, which is coupled to the light guide 3. When moving the object 1, the light spot irradiates the heat-sensitive strips 4 connected to the contact pads 5. The heat-sensitive strips 4 are located on the surface of the substrate 6 in the form of the first and second rows relative to the common bus 7 The strips of the first row are offset relative to the second row by one heat-sensitive strip. The distance between the strips is equal to the size of the strip.

Figure 3 shows a view from the back of the substrate of the linear displacement sensor. On the reverse side of the cradle 6 is a film heater 8 in the form of a zigzag tape made of NiCr and a film thermocouple 9 made of Cu-Ni.

When moving the object of observation 1, a light source 2 mounted on it scans the heat-sensitive strips 4 of the sensor. When scanning the corresponding heat-sensitive strip of the first or second rows with a light source, it heats up and changes its resistance, and this change in resistance is stored in memory, since the heat-sensitive layer based on the VO ₂ film is thermostated in the middle of the hysteresis loop. The presence of the internal memory of the thermosensitive layer of the sensor provides unambiguous measurement of the magnitude of the movement of the object of observation.

Figure 4 shows the design of the sensor of angular displacements. A radiation source 2 is installed at the observation object 1, which is coupled to the light guide 3. When moving the object 1, the light spot irradiates the heat-sensitive strips 4 connected to the contact pads 5. The heat-sensitive strips 4 are located on the surface of the substrate 6 in the form of the first and second rows relative to the common bus, made in the form of a ring 7. The strips of the first row are offset relative to the strips of the second row by one heat-sensitive strip. The common bus 7 has a metallized terminal on the opposite side of the substrate 6, made in the form of a disk.

Figure 5 shows a view from the back of the substrate of the sensor of angular displacements. On the reverse side of the substrate 6 is placed a NiCr film heater 8 in the form of a zigzag ribbon forming a ring and a Cu-Ni film thermocouple 9.

Figure 6 presents the control circuit of the displacement sensor, equipped with an LED indicator.

The control circuit records the change in the resistance of the strip 4 of the thermally sensitive layer of the sensor irradiated at a given time. The number of strips of the heat-sensitive layer of the sensor, which have changed their resistance during the movement of the object of observation, is indicated on the LED display.

The generator 10 sets the polling frequency of the thermosensitive strips of the sensor. The pulses from the generator 10 are supplied to the corresponding binary dividers for the decoding selectors of the switch 11 and decimal dividers for the display circuit 14. The outputs of the analog switch 11 are connected to the comparator 12. From the output of the comparator 12, the signal is supplied to a set of hexadecimal counters 13. From the output of the counters 13, the signal is fed to two-digit decimal LED indicator 14. The control circuit fixes the number of strips that have changed the resistance value during the movement of the object, which is indicated on the LED tab lo.

An implementation of a control circuit is given, which is an analog switch in the form of a combination of m / s K651KP2, the outputs of which are connected to a comparator based on K554CA3. From the output of the comparator, the signal is supplied to a set of hexadecimal counters based on K561IE10. The inputs of the meters are connected to a master oscillator based on K561LA7. The generator 10 sets the polling frequency of the strips of the heat-sensitive layer of the sensor. Pulses from the generator are supplied to the corresponding binary dividers for decoding selectors m / s switch 11 and decimal dividers for the display circuit 14. The indication is carried out on a two-digit decimal LED indicator ALS314B 14.

The accuracy of monitoring the sensor of linear or angular displacements of the object of observation is determined by the size of the heat-sensitive strip 4 of the sensor.

Thermal linear and angular displacement sensors are made of VK-100 ceramics with a thickness of 0.5 mm. The shape of the substrate in the form of a rectangle or disk is determined by the type of sensor, and their size by the range of linear and angular movements of the radiation object.

The implementation of the measuring scale in the form of the first and second rows of heat-sensitive strips with an offset of one row relative to another by one strip ensures the accuracy of control of linear or angular movements equal to the size of the heat-sensitive strip.

The sizes of the heat-sensitive strips are 30 × 30 μm ² , the gap between the strips is 30 μm. The second row of heat-sensitive strips is offset from the first row by 30 μm. These are the usual features of photolithography.

If we use the method of dimensional laser processing of VO ₂ thin films, then the sizes of the heat-sensitive strips can be brought to 1 × 1 μm ² , thus, the maximum resolution of the linear displacement sensor can be 1 μm over a length of 50 mm.

As for the angular displacement sensor, its resolution when moving the object of observation in the range of 360 ° is 8 angles. with a substrate size of 90 × 90 mm ² .

Thus, in comparison with existing linear and angular displacement sensors, the proposed sensors have twice as much resolution and are absolute sensors of linear and angular displacements (their output signal unambiguously indicates the position of the observed object).

Information sources

1. Aliev T.M., Ter-Khachaturov A.A. Measuring equipment: Textbook for technical universities. - M.: Higher School, 1991, 384 p.

2. Brindley K. Measuring Transducers: Reference Guide: Translation from English. - Energoatomizdat, 1991, 144p. - prototype.

Claims (2)

1. The displacement sensor containing a light source mounted on the object of observation, a substrate with a rectilinear or angular scale formed by absorbing strips located on the substrate at a distance from each other equal to the size of the strip, and the interface of the measuring system, characterized in that the strip on the substrate located with the formation of the first and second rows of strips separated by a common conductive bus, and the strips of the first row are shifted relative to the strips of the second row by one strip, the strips are made of material hysteresis dependence of resistance on temperature, and each strip is provided with a signal terminal on the other side of the substrate film has a heater and a thermocouple temperature sensing strips are connected to the analog switch, a part of the measuring system interface. 2. The displacement sensor according to claim 1, characterized in that the heat-sensitive strips are made on the basis of a VO ₂ film.

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