JP3541660B2 - Magnetic tape controller - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a magnetic tape control device that is effective when used in a video tape recorder (hereinafter, referred to as a VTR).
[0002]
[Prior art]
In recent years, the size and weight of a VTR, particularly a camera-integrated VTR, have been remarkably reduced.
[0003]
Hereinafter, a conventional VTR magnetic tape control device will be described.
FIG. 4 is a schematic view of a magnetic tape traveling system of a conventional helical scan type VTR as viewed from above. In FIG. 4, reference numeral 20 denotes a tape, which is provided at a magnetic tape 20a on which video and audio signals are recorded, and at a beginning and an end of the magnetic tape 20a (portion connected to both reels) which cannot record a signal and which is substantially transparent. And a leader tape 20b provided. Reference numeral 13 denotes a head drum having a magnetic head that records a video signal and an audio signal on a magnetic tape 20a by rotating; 14, a capstan shaft rotated by a motor (not shown); A pinch roller for nipping and running the tape 20; 16 a tape supply reel (hereinafter referred to as S reel) around which the tape 20 is wound; 17 a tape take-up reel (hereinafter T reel) around which the tape 20 is wound Reference numeral 18 denotes a light emitting diode, 19a denotes a first light receiving element disposed near the S reel 16 for detecting an optical signal output from the light emitting diode 18 via the tape 20, and 19b is disposed near the T reel 17. This is a second light receiving element that detects an optical signal output from the light emitting diode 18 via the tape 20. In the light receiving elements 19a and 19b, when an optical signal from the light emitting diode 18 is detected, it is determined that the leader tape 20b is running, and when no optical signal is detected, it is determined that the magnetic tape 20a is running. . Point A is the point where the leader tape 20b is detected first, and point B is the point where the tape 20 starts to contact the head drum 13. Arrow a indicates the direction in which the tape 20 runs in the forward direction.
[0004]
The operation of the magnetic tape traveling system in the conventional VTR configured as described above will be described below.
[0005]
The tape 20 is sandwiched between a capstan shaft 14 directly connected to a rotating capstan motor and a pinch roller 15, and is transported in the direction of arrow a. The tape 20 is supplied from the S reel 16 and wound by the T reel 17. When the tape on the S reel side is near the end, the leader tape 20b provided at the end of the tape 20 passes through the point A. However, since the leader tape 20b is a light-transmitting material, The optical signal passes through the leader tape 20b and is detected by the first light receiving element 19a to detect the end of the tape.
[0006]
After the end of the tape is detected by the first light receiving element 19a, the capstan motor is stopped immediately, the rotation of the capstan shaft 14 is stopped, and the transfer of the tape 20 is stopped. Here, if the transfer of the tape 20 is not stopped immediately after the end of the tape is detected, and if the tape 20 is running at a high speed until the end of the tape of the S reel 16, abnormal tension is applied to the tape 20 and tape damage or the like may occur. . If the leader tape 20b is moved to the point B, the head drum 13 rotating at a high speed scans the leader tape 20b, so that the head provided on the head drum 13 may be clogged.
[0007]
[Problems to be solved by the invention]
However, in the above-described configuration, the tape speed at the time of high-speed reproduction or high-speed reverse reproduction (CUE / REV) or fast-forward or rewind (FF / REW) of the tape 20 depends on the tape speed during normal reproduction or recording. Since the speed is several times to several tens times the speed and the length of the leader tape 20b is relatively short, if the tape transfer is not stopped immediately after the first light receiving element 19a detects the leader tape 20b, the tape damage may occur. And clogging of the head occurs.
[0008]
In recent years, the distance between the point A and the point B has been shortened with the miniaturization of the camera-integrated VTR, and it has become quite difficult to control the tape from high-speed running to quick stop as described above. ing.
[0009]
An object of the present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to provide a magnetic tape control device that can stop a magnetic tape stably from high-speed running in a short time.
[0010]
[Means for Solving the Problems]
In order to achieve this object, a magnetic tape control device according to the present invention is a tape control device capable of nipping and transporting a tape by a capstan and a pinch roller, wherein a motor for rotating the capstan and the motor are provided. A drive circuit that controls the drive, a frequency generator that detects the rotational speed of the capstan rotated by the motor, a waveform shaping circuit that shapes the output signal of the frequency generator, and an output signal of the waveform shaping circuit. A variable frequency divider for dividing the frequency, a period measuring device for measuring the period of the output signal of the variable frequency divider, and when stopping the tape from running, the drive circuit issues a reverse rotation command to the motor, the cycle was measured based on the period measured by the measuring instrument by lowering the frequency division ratio of the variable frequency divider, and to the drive circuit on the basis of a period measured by the period measuring instrument In which a control means for controlling the torque of the motor.
[0011]
With the above configuration, the magnetic tape can be stably stopped in a short time from high-speed running.
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
An invention according to claim 1 of the present invention is a tape control device capable of nipping and transporting a tape by a capstan and a pinch roller, comprising: a motor for rotating the capstan; and a drive for driving and controlling the motor. A circuit, a frequency generator for detecting a rotation speed of a capstan rotated by the motor, a waveform shaping circuit for shaping a waveform of an output signal of the frequency generator, and a variable for dividing the output signal of the waveform shaping circuit. A frequency divider, a period measuring device for measuring the period of the output signal of the variable frequency divider, and when stopping the tape from running, the drive circuit issues a reverse rotation command to the motor and measures the period with the period measuring device. the torque of the motor by the driving circuit based on the period measured period by lowering the frequency division ratio of the variable frequency divider, and which has been measured by the period measuring instrument on the basis of the period It is those in which a Gosuru control means may stop short time and stabilizes the magnetic tape from the high-speed running.
[0013]
An invention according to claim 2 of the present invention is a tape control device capable of nipping and transferring a tape by a capstan and a pinch roller, comprising: a motor for rotating the capstan; and a drive circuit for driving and controlling the motor. A frequency generator that detects a rotation speed of a capstan rotated by a motor, a waveform shaping circuit that shapes a waveform of an output signal of the frequency generator, a variable frequency divider that divides an output signal of the waveform shaping circuit, A period measuring device for measuring the period of the output signal of the variable frequency divider; and control means for controlling the variable frequency divider and the drive circuit based on the period measured by the period measuring device. When the control is stopped, the control means gives a command to the drive circuit to reverse the motor and applies the maximum torque to the motor, and the cycle of the output signal of the variable frequency divider becomes the first cycle. In conjunction with lowering the frequency division ratio of the variable frequency divider to reduce the torque of the motor, the period of the output signal of the variable frequency divider is a variable frequency divider for frequency dividing ratio the first when it is a second cycle The motor is controlled to stop the motor when the cycle of the output signal of the variable frequency divider reaches the third cycle by further decreasing the torque applied to the motor and lowering the magnetic tape from the high-speed running. In order to stop the magnetic tape in a short time, a maximum reversal torque is applied to the capstan motor for transferring the magnetic tape when the tape stops, and at the same time, the FG cycle is measured to observe the rotation speed of the motor. If the reversing torque continues to be applied, the motor will eventually stop and eventually reverse, so it is important to stop the motor with good timing. In order to realize this, the FG cycle is measured. When the capstan motor is rotating at high speed, the FG cycle is also very short. Therefore, the FG is divided and measured. By lowering the frequency division ratio of the frequency divider, the measurement accuracy of the FG cycle is increased. The FG cycle is measured while decelerating the motor, the FG cycle is measured while repeating the reduction of the FG dividing ratio and the measurement accuracy of the FG cycle, and the predetermined FG cycle which is regarded as immediately before the rotation of the capstan motor stops. The motor is stopped at the point when reaches. In addition, in the process of deceleration, the reverse torque applied to the capstan motor is maximized so that the speed is reduced in a short time, and immediately before the stop, the torque is controlled so as to decrease the torque. This is because even if the motor is suddenly stopped due to the inertia moment of the motor, the motor attempts to maintain the rotation speed according to the law of inertia, so that the motor is not decelerated very quickly immediately before the stop.
[0014]
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
(Embodiment 1)
FIG. 1 is a schematic diagram of a magnetic tape traveling system in a helical scan type VTR of the present embodiment. In FIG. 1, reference numeral 20 denotes a tape, which is provided on a magnetic tape 20a on which video and audio signals are recorded, and on a start and end (portions connected to both reels) of the magnetic tape 20a which cannot record signals and are substantially transparent. And a leader tape 20b provided. Reference numeral 13 denotes a head drum having a magnetic head that records a video signal and an audio signal on a magnetic tape 20a by rotating; 14, a capstan shaft rotated by a motor (not shown); A pinch roller 21 for nipping and running the tape 20 is a capstan control circuit for controlling the rotation of the capstan shaft 14, and its detailed configuration will be described later with reference to FIG. 16 is a tape supply reel around which the tape 20 is wound (hereinafter referred to as S reel), 17 is a tape take-up reel around which the tape 20 is wound (hereinafter referred to as T reel), 18 is a light emitting diode, and 19a is A first light receiving element, which is arranged near the S reel 16 and detects an optical signal output from the light emitting diode 18 via the tape 20, 19 b is an optical signal arranged near the T reel 17 and outputs the optical signal output from the light emitting diode 18 to the tape. 20 is a second light receiving element that detects through the second light receiving element 20. In the light receiving elements 19a and 19b, when an optical signal from the light emitting diode 18 is detected, it is determined that the leader tape 20b is running, and when no optical signal is detected, it is determined that the magnetic tape 20a is running. . Point A is the point where the leader tape 20b is detected first, and point B is the point where the tape 20 starts to contact the head drum 13. Arrow a indicates the direction in which the tape 20 runs in the forward direction.
[0015]
FIG. 2 is a block diagram showing a configuration of the capstan control circuit 21 of FIG. 1 in the present embodiment. In FIG. 2, 1 is a tape, 2 is a capstan, 22 is a capstan motor for rotating and driving the capstan 2, 3 is a pinch roller for holding the capstan 2 and running the tape 1, and 4 is for rotating the capstan 2 The driving circuit 5 for driving is a frequency generator that detects the rotation frequency (rotation speed) of the capstan 2 and outputs an FG signal. The frequency generator 5 is composed of a magnet, and includes a plurality of magnets provided on the capstan 2. The rotational frequency is detected from the positional relationship of. 6, a waveform shaping circuit for amplifying and shaping (rectangular wave shaping) the FG signal detected by the frequency generator 5; 7, a variable frequency divider for dividing the FG signal output from the waveform shaping circuit 6; A period measuring device that measures the period of the FG signal divided by the variable frequency divider 7. Control device 9 controls the variable frequency divider 7 and the drive circuit 4 based on the period measured by the period measuring device 8. Certain microcomputers (hereinafter, referred to as microcomputers), 10 to 12, are command signals output from the microcomputer 9 to the variable frequency divider 7 and the drive circuit 4, and 10 is a change in the frequency division ratio with respect to the variable frequency divider 7. A command signal 11 is a rotation control signal for controlling the forward rotation, reverse rotation, and stop of the capstan motor 22 to the drive circuit 4, and a motor torque command signal 12 is for controlling the motor torque of the capstan motor 22.
[0016]
The operation of the magnetic tape traveling system of the VTR according to the present embodiment configured as described above will be described below.
[0017]
The tape 20 is transported in a direction indicated by an arrow a between the capstan shaft 14 and the pinch roller 15, which rotate under the control of the capstan control circuit 21. The tape 20 is supplied from the S reel 16 and wound by the T reel 17. When the tape on the S reel side is near the end, the leader tape 20b provided at the end of the tape 20 passes through the point A. However, since the leader tape 20b is a light-transmitting material, The optical signal passes through the leader tape 20b and is detected by the first light receiving element 19a to detect the end of the tape. After the end of the tape is detected by the first light receiving element 19a, the capstan motor is stopped immediately, the rotation of the capstan shaft 14 is stopped, and the transfer of the tape 20 is stopped.
[0018]
Hereinafter, the operation of the capstan control circuit 21 will be described.
The rotation frequency (rotation speed) of the capstan motor 22 is detected by the frequency generator 5 and an FG signal is output to the waveform shaping circuit 6. The FG signal from the frequency generator 5 is amplified and shaped into a rectangular wave by the waveform shaping circuit 6 and frequency-divided by the variable frequency divider 7. The frequency-divided FG signal is input to the period measuring device 8 to measure the period, and is input to the microcomputer 9. The microcomputer 9 includes a frequency division ratio change command signal 10 that is a command to the variable frequency divider 7 and a rotation control that is a command to the drive circuit 4 to rotate the capstan motor 22 forward, reverse, and stop. The timing at which the signal 11 and the motor torque command signal 12 are issued is created based on the cycle measurement result from the cycle measuring device 8.
[0019]
FIG. 3 is a timing chart of each part in the configuration of FIG. 2 of the present embodiment, and is a timing chart when the tape is stopped in a short time from a high-speed running of 30 times speed as an example. FIG. 3A shows forward rotation, reverse rotation, and stop commands to the capstan motor 22 (corresponding to the rotation control signal 11 in FIG. 1). 4B shows the output waveform of the waveform shaping circuit 6, FIG. 4C shows the FG waveform after frequency division by the variable frequency divider 7, and FIG. 4D shows the change in the frequency division ratio of the variable frequency divider 7. FIG. 7E shows a waveform of the motor torque command signal 11, and FIG. 7F shows a waveform showing a change in the rotation speed of the capstan motor 22 (from 30 × speed to stop). Point X0 is a timing at which the leader tape 20b is detected at the point A in FIG. 1 to start deceleration of the tape, points X1 and X2 are timings at which the frequency dividing ratio of the variable frequency divider 7 is changed, and at point X2, the motor torque is also reduced. Has been reduced. The point X3 is the stop timing of the capstan and the tape. The time from the point X0 to the point X3 is set shorter than the winding time of the leader tape. This is to prevent the tape from reaching the end while traveling at high speed.
[0020]
The rotation control of the capstan will be described in more detail with reference to FIG. First, when the capstan 2 is rotated at a high speed and the tape is running at 30 times the normal speed, the tape is stopped at the point X0 in FIG. By issuing a rotation command and applying the maximum torque to the capstan motor 22 as shown in (E), the rotation speed of the capstan 2 starts to decrease as shown in (F). At this time, the frequency division ratio (D) of the variable frequency divider 7 is reduced from 1/30 frequency division to 1/15 frequency division.
[0021]
Next, at a point X1 when it is detected that a predetermined time has elapsed and the pulse cycle of the frequency divider output (C) has reached a predetermined value T1 (first cycle), the frequency division ratio (D ) Is reduced from 1/15 frequency division to 1/8 frequency division. This is because when the capstan is rotating at high speed, the FG cycle is also very short, so that erroneous detection may occur in the cycle detector 8. Therefore, the frequency of the FG signal is divided by the variable frequency divider 7, the period is measured by the period detector 8, and when the FG signal is decelerated to a predetermined period or more, the frequency dividing ratio of the variable frequency divider 7 is reduced. Erroneous detection of the cycle in the detector 8 is eliminated, and the measurement accuracy of the FG cycle can be improved.
[0022]
At a point X2 where the pulse cycle of the output (C) of the variable frequency divider 7 has reached a predetermined value T2 (second cycle), a frequency division ratio is set in order to improve the detection accuracy of the FG signal in the variable frequency divider 7. (D) is controlled to be reduced from 1/8 frequency division to 1/4 frequency division. At this point X2, the capstan motor 22 lowers the reversal torque by the motor torque command signal (E) from the microcomputer 9 as compared to before the period T2.
[0023]
This is to ensure that the rotation of the motor is stopped when the capstan motor is stopped (point X3). That is, when the capstan motor 22 reaches the point X3 with the reversal torque up to the point X2 and brakes the capstan motor 22, the rotation temporarily stops but the reversal torque is large. And the tape 1 may start running backward. Therefore, by suppressing the reversing torque at the point X3 as much as possible, the reversing torque of the capstan motor 22 can be suppressed when the brake is applied, and the reverse rotation of the capstan motor 22 after the brake is released can be prevented. 1 can be prevented from running in reverse.
[0024]
If the capstan motor 22 that is rotating at high speed is braked and suddenly stopped, the capstan motor 22 tries to maintain the rotational speed before the sudden stop according to the law of inertia. If the capstan motor 22 keeps rotating as it is due to inertia even after a sudden stop, the tape 1 reaches the end of the tape while traveling at high speed, so that abnormal tension is applied to the tape 1 and tape damage occurs. In order to reduce the inertia of the capstan motor 22, it is necessary to stop the reversing torque as much as possible without reducing the reversing torque as much as possible immediately before stopping.
[0025]
It is detected that the pulse cycle of the output (C) of the variable frequency divider 7 has become a cycle T3 (third cycle) at a speed at which the capstan motor 22 can be stopped by applying a brake to the capstan motor 22. At point X3, the microcomputer 9 controls the drive circuit 4 to stop the capstan motor 22, and the drive circuit 4 applies a brake to the capstan motor 22. That is, the capstan motor direction command (A) from the microcomputer 9 to the drive circuit 4 is a stop signal, and the motor torque command (E) is a no-torque command. The drive circuit 4 stops the capstan motor 22 according to the capstan motor direction command and the motor torque command. The reason why the no-torque command is sent is to prevent the capstan motor 22 from rotating in the reverse direction. Therefore, the tape 1 stops at the timing of X3, that is, stops immediately before the end of the tape.
[0026]
As described above, according to the present embodiment, in order to stop the tape from running at high speed, the taper is suddenly decelerated by applying the reverse torque and the maximum torque to the capstan motor 22 and decelerating by using the variable frequency divider 7. At the same time, the motor can be stopped in the shortest time by decelerating while changing the frequency division ratio and the deceleration torque, and the motor stop control can be performed so as not to reach the end of the tape while traveling at high speed.
[0027]
【The invention's effect】
As described above, according to the present invention, the tape can be stopped in the shortest time from high-speed running, and since the tape does not reach the end of the tape while running at high speed, tape damage due to abnormal tape tension or a stopped tape An excellent effect is obtained in that tape stop control capable of preventing head clogging due to head scanning can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a magnetic tape traveling system of a helical scan type VTR according to an embodiment of the present invention. FIG. 2 is a block diagram of a capstan control circuit in a magnetic tape control device according to the embodiment. FIG. 4 is a timing chart of each part of a capstan control circuit in the embodiment. FIG. 4 is a schematic diagram of a magnetic tape traveling system of a conventional helical scan type VTR.
DESCRIPTION OF SYMBOLS 1 Tape 2 Capstan motor 3 Pinch roller 4 Drive circuit 5 Frequency generator 6 Waveform shaping circuit 7 Variable frequency divider 8 Period measuring instrument 9 Microcomputer

Claims (2)

A tape control device capable of nipping and transporting the tape by a capstan and a pinch roller,
A motor for rotating the capstan,
A drive circuit for driving and controlling the motor,
A frequency generator for detecting the rotation speed of the capstan rotated by the motor,
A waveform shaping circuit for shaping the output signal of the frequency generator,
A variable frequency divider for dividing the output signal of the waveform shaping circuit,
A period measuring device for measuring the period of the output signal of the variable frequency divider,
When stopping the tape from running, the drive circuit issues a reverse rotation command to the motor , measures the cycle by lowering the frequency dividing ratio of the variable frequency divider based on the cycle measured by the cycle measuring device , And a control means for controlling the torque of the motor by the drive circuit based on the cycle measured by the cycle measuring device. A tape control device capable of nipping and transporting the tape by a capstan and a pinch roller,
A motor for rotating the capstan,
A drive circuit for driving and controlling the motor,
A frequency generator that detects the rotation speed of the capstan rotated by the motor, and a waveform shaping circuit that shapes the output signal of the frequency generator,
A variable frequency divider for dividing the output signal of the waveform shaping circuit,
A period measuring device for measuring the period of the output signal of the variable frequency divider,
Control means for controlling the variable frequency divider and the drive circuit according to the cycle measured by the cycle measuring device,
The control means, when stopping the tape from high-speed running, the control means gives a command to the drive circuit to reverse the motor and apply the maximum torque to the motor,
When the cycle of the output signal of the variable frequency divider becomes the first cycle, the frequency of the variable frequency divider is reduced and the torque of the motor is reduced. When the second cycle is reached, the frequency division ratio of the variable frequency divider is further reduced from that in the first cycle, and the torque applied to the motor is sequentially decreased. A magnetic tape control device, wherein the motor is controlled to stop when the number of cycles becomes three.

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