SU656104A1 - Method of measuring transverse oscillation of electrostatic information-recording tape carrier - Google Patents

Description

signal, and the magnitude of the transverse oscillations of the carrier is determined by the difference between the received and filled codes.

The drawing shows a block diagram of an apparatus for carrying out the method.

The electrostatic head 1, which is a system of isolated open discrete elements, and a CRT 2 with a metal fiber screen are installed perpendicular to the counter electrodes 3 and 4 and the moving electrostatic tape carrier 5, on which the head 1 records the control signal 6 in the form of straight lines.

The generator 7 short pulses connected to the input of the switch 8, to another input of which is connected to the output of the generator 9 pulses. Each output of the switch 8 is connected to a specific group of discrete electrodes of the electrostatic head 1. A sawtooth voltage generator 10 is connected to the input of a deflecting system of a CRT 2, the cathode of which is connected to the output of a constant voltage source 11. Another output of the generator 10 is connected to the inputs of the generators 9 and 7.

A counter electrode 3 grounded through a resistor 12 through an amplifier 13 and a converter 14 is connected to the input of memory 15. One of the outputs of generator 10 is connected to the input of a 16 clock pulse generator, the output of which is connected to the input of counter 17 pulses in a frame connected to the counter of 18 frames. A frame is defined as the number of pulses recorded along a line perpendicular to the direction of movement of the carrier. The output of the pulse counter 17 in the frame is connected to the input of the storage device 15, to the input of the counter 18 and the clock pulse generator 16. The output of the frame counter 18 is connected to the time 19, the storage device 15 and to one of its inputs. The outputs of the setting device 19 are connected to the inputs of the device 15. The counter electrode 4 is grounded through a resistor 20 through an amplifier 21, a converter 22 and a multiplication device 23 connected to an input of a subtracting device 24, the output of which is connected to the input of the recorder 25, and the other inputs of which are connected to a storage device 15 , a generator of 16 clock pulses and a time setting device 19.

A method for measuring transverse vibrations of a tape information carrier during playback is carried out as follows.

The electrostatic carrier tape 5 is pulled at a constant speed by a tape mechanism in the gap between the recording head 1 and the counter electrode 3, as well as the reading CRT 2 with the counter electrode 4. The electrodes of the head 1 are divided into groups. Each group of electrodes is connected to a specific output of the switch 8, which is switched by recalculating the pulses fed to the switch 8 from the output of the generator 9.

Each group of electrodes receives a signal from the output of a generator of short pulses. As a result of the occurrence of a large potential difference between the ends of the electrode group and the carrier 5, the gap is broken and the charge is transferred to the carrier. The magnitude of this charge is directly proportional to the capacitance between the ends of the electrodes of the head 1 and the carrier. 5. When moving, the carrier 5 is subjected to perpendicular and transverse

oscillations m. The capacity of this gap is directly proportional to the perpendicular vibrations of the carrier when it moves. Portable charge in the form of a current flows through the carrier 5, counter electrode 3, resistor 12. Therefore, the current flowing through resistor 12, grounding counter electrode 3, depends on the laws of perpendicular oscillations, i.e., an amplitude-modulated signal is removed from the resistor. Before recording in a static state, 5 research institutes fix a certain gap between the ends of the electrode and the carrier. In the dynamic mode, the gap changes due to perpendicular vibrations. Consequently, the radius of the spot formed on the carrier also changes. Radius

the recorded spot is proportional to the perpendicular oscillations, the recorded pulse signal is also modulated by the perpendicular oscillations. Thus, the law of change of current taken from

5 of resistor 12, and the law for changing the width of the spot has the same character and is different in proportionality coefficient. Therefore, the signal taken from the resistor 12 is amplified in the amplifier 13 and the amplitude-pulse-modulated signal (AIM) is converted into a code-pulse-modulated signal (CMM) using converter 14, from the output of which the code goes to the input of the device 15. When forming The generator 7 short pulses from the output of the latter to the input of the generator 16 receives a trigger pulse. Clock pulses arrive at the input of the counter 17 pulses in the frame. This counter counts the number of discrete spots that are written across the width of the carrier. The pulse counter in the frame forms the younger bits of the address of the memory cell in which this code will be written. In addition, the clock pulses arrive at the time setting device 19, which, when the permissive signal from the output of the frame counter 18 synchronously with the clock pulses, generates a signal pulse “recording which is fed to the input of the device 15. From another output

the frame counter to the input of the storage device 15 receives the high-order bits of the cell address into which this code should be written. At the end of the first frame, i.e. after recording the last pulse in the frame, the counter 17 records the number corresponding to the number of transmitted pulses. According to this feature, a signal is generated at the output of the counter 17, which is fed to the generator 16 and prohibits the generation of clock pulses and simultaneously writes 18 units into the frame counter, and the counter 17 is zeroed. The sawtooth generator 10 and the short pulse generator are synchronized. During the return stroke of the beam, the voltage of the generator 10 starts the generator 16.

The recording continues until, in the frame counter, the number corresponding to the number of frames from the recording frame to the reading frame is written.

As soon as a given number appears in the counter 18, a signal is generated at its output, which is fed to the setpoint generator 19, which, synchronously with the clock pulses, begins to generate a signal pulse reading. At the same time, frame counter 18 is zeroed.

When the beam hits the ends of the electrodes of a metal-fiber screen of a CRT 2, the absolute value of their potential increases sharply. There is a breakdown of the air gap screen carrier. The gap in the static mode is the same between the carrier 5 and the head 1, and between the carrier 5 and CRT 2. When a beam of CRT 2 hits the screen electrodes opposite the uncharged portions of the carrier, the resistor 20 and the current flow through the last counter electrode 4 which creates on the resistor 20 a voltage drop of zero level. When a CRT beam 2 hits the screen electrodes located opposite the charged sections 6 of the carrier 5, the charge is also transferred to the carrier 5, the magnitude of which depends, firstly, on the potential difference of the CRT screen and the control signal section 6, secondly, on the size of the air gap screen carrier.

A pulse is formed on the resistor 20, the duration of which is equal to the scanning time of the CRT beam 2 across the carrier. The duration of this pulse depends on the width of the recorded spot and on the transverse oscillations of the carrier during playback, since if the velocity vectors of the beam and the oscillations coincide, the duration formed on the resistor 20 nM pulses is longer than the duration of the pulse generated in the absence of transverse oscillations. Pulses removed from resistor 20 are modulated both in duration and

in amplitude. These pulses are amplified using amplifier 21. A pulse width modulated (PWM) signal (the amplitude of these pulses is not taken into account) is converted into a pulse code modulated signal (CMM) using a converter 22. This code at the output of multiplier 23 carries information about the width of the spot when recording, taking into account the transverse vibrations during reproduction, since it is multiplied by the scanning speed of the beam. This code is fed to the input of the subtractor 24.

During the reverse of the voltage from the generator 7, a signal is sent to the clock pulse generator 16 that triggers the latter. The clock pulses trigger the counter 17, which begins to form the lower bits of the cell address, from which it is necessary to read the corresponding code. These bits go to the input of the storage device 15. The leading bits of the address to the input of the memory come from the output of the frame counter 18. Synchronously with the clock pulses, the time setting knob 19 generates pulses of the “read” signal, which also arrive at the input of the device 15. Thus, after the carrier travels the distance between the head 1 and the CRT 2, the code corresponding to the width of a certain charging spot is written out from the corresponding memory cell.

The difference of these two codes corresponds to the transverse oscillations of the section of the carrier on which the signals are recorded.

The resulting difference for each pulse is recorded by the recorder 25, and the subtractive device is zeroed at the trailing edge of the clock pulse.

When writing to the counter 18 frames of the number corresponding to the number of recorded frames, a signal is generated. It tilts the counter 18 and goes to the setpoint controller 19, through which the latter starts synchronously with the clock pulses to generate a pulse of the recording signal. Thus, the operation of the device continues and the lateral oscillations of the carrier are determined during reproduction.

The proposed method improves the accuracy of measuring transverse vibrations of the carrier during playback.

Claims (2)

1. For the number 2342048 / 18-10, cl. G 11 B 27/10, 1976, according to which the decision to issue an author's certificate was made. 2. Forward number 2354295/10, cl. G 11 B 27/10, 1976, according to which the decision to issue an author's certificate was made.