A well-known weight sensor (see Weight Sensor BP34 by Sartorious) has been used as a base model and comprises a string shaped sensitive element made of tungsten and rhenium glass rod that is clamped in clamps and placed into the field of permanent magnet.

The disadvantage of this device (see Weight Sensor BP34 by Sartorious) is the fact that it is used solely for the purpose of weighing of the crucible that serves for single crystals growth, as opposed to weighing of the single crystal itself. This reduces the device's measuring precision due to conducting indirect measuring of the single crystal as well as the fact that the aforementioned device has not been designed for rotation.

At the base of the invention there was a task of achieving better measuring precision of the variable at the time of weighing of the single crystal in growth, by using a string transformer that has a digital outlet attached on the boards that provide power supply for the string sensor and transmit a signal to the computer.

The task in question has been solved by the design of the string sensor that comprises a string shaped sensitive element made of tungsten and rhenium glass rod that is placed into the frame as well as into the field of permanent magnet, in accordance with the invention, where the boards are placed under a hermetic casing that provides power supply for the sensor and transmission of the signal to the computer. The effect of the invention is based upon a structure where one of the boards rotates along with the weight sensor while the other remains static. Power is transmitted via a transformer that rotates, by one part of, it is fixed to the dynamic board, and by the other to the static one. Signal to the computer will be transformed via an optoelectronic couple : light- emitting diode (LED) and phototransistor that are placed coaxially. The LED is fixed to the board that rotates while the phototransistor is fixed to the static board. All parts of the structure have been assembled in an axially symmetric manner to minimize imbalance when the weight sensor rotates.

This solves the task of measuring of the variable at the moment of weighing of a growing single crystal, i. e. measuring of the single crystal that rotates, moves and grows in the vacuum or in a specially made gas environment is conducted.

Signal that is received from the weight sensor in a digital format meets the requirements of the computerized system of control more efficiently. The data received indicate resolution of the sensor at 0.1-0. 2 grams for 10 kg.

The essence of the invention can be seen in the drawings in greater detail, as Figure 1 shows a full size image of the weight sensor and Figure 2 shows a section image of the device.

String weight sensor contains a string-shaped sensitive element (1) made of tungsten and rhenium glass rod clamped in clamps (2 and 3). Diameter of the rod depends on the boundary weight required that can be measured.

The string of the sensitive element (1) is placed in the field of permanent magnet, in the gap between the polar rod ends (4 and 5), in particular. The shape formed creates the necessary tension for the magnetic field.

The top clamp (1) of the sensitive element (1) is attached to the electrolyzed bearing by hinges.

To the bottom clamp (3), there is a safety clutch also attached by hinges (6) that protects the string (1) from breaks, in case the weigh exceeds the border limit allowed. The safety clutch (6) attached by centering rims (7) that possess great radial stiffness for transmitting the rotating mode as well as minimal axial mode so that not to create a prop during transmission effort (weight of the growing single crystal) to the string of the sensitive element (1).

The entire above-mentioned structure is fitted into a hermetic casing (8) that enables work of the string-shaped sensitive element (1) in the vacuum or in the gas environment.

There are two boards (9 and 10) above the hermetic casing that provide power supply for the sensor and transmission of the signal to the computer. The first board (9) rotates along with the weight sensor the other remains static. Power supply is transmitted by a transformer (11) that rotates: one part of the transformer is fixed to the static board, as the other is fixed to the dynamic board (10).

Signal is transmitted through an electronic optical couple that includes a light emitting diode (LED) (12) and a phototransistor (13), where the LED (12) is part the board that rotates while the phototransistor (13) is part of the static board. The LED and the phototransistor are placed coaxially.

The principle of operation of the string weight sensor is based on the dependence of oscillation frequency fluctuations of the string upon the change of tightening force, as well as on the change of the weight of the crystal in growth.

The weight of the growing crystal is attached to the axle of a rod end (6) that is attached to the bottom clamp (3) of the string of the sensitive element (1). A self-excited oscillator (the string (1) is a part of it) creates string oscillations in the permanent magnetic field. Frequency of these oscillations corresponds to the level of tightening of the string (weight of the single crystal). If the level of tightening were to change (oscillation frequency of fluctuations of the string (1) changes along with the weight of the single crystal. Electrical impulses of the frequency dependent on the self-excited oscillator will transmit via the optoelectronic couple that contains an LED (12) and a phototransistor powered to reach the TTL level (5B), and then are transmitted to the computer for processing.

By utilizing the string sensor in question, higher precision of measuring and higher sensibility can be achieved. These will allow to conduct automated growing of single crystals from a seed crystal with preset geometric specifications. This also allows to increase the output.

Industrial Applicability This string weight sensor can be utilized in the semiconductor industry for the purposes of single crystal growth, e. g. in the units/workstations for oxide single crystals growth.

This string weight sensor can be used on units/workstations where the Czokhralski or Kyropoulus method is applicable.

This device has been designed to serve the purpose of control of the diameter by measuring/weighing of a single crystal in growth.

By utilizing this string sensor of weight on workstations, the precision of shape control that can be achieved is not available by utilizing any of the existing weight sensors. String weight sensor specifications list Figs. 1, 2 1. String of the Sensitive Element 2. Upper Clam of the Sensitive Element 3. Lower clam of the Sensitive Element 4. Permanent magnet with the N Pole 5. Permanent magnet with the S Pole 6. Safety Clutch 7. Centering Rim 8. Hermetic Casing 9. Driver Board (dynamic) 10. Transformer Board (static) 11. Transformer 12. Light Emitting Diode 13. Phototransistor Single Crystal Growth Device for High Temperature Materials Specifications List 1-String weight sensor 2-Electronic section of weight sensor 3-Power cabinet 4-Control rack 5-Industrial workstation 6-Control unit 7-Vacuum set 8-Chamber 9-Manual control unit