JPS59104742A - Tape driving controller - Google Patents

Abstract

PURPOSE:To reduce both capacity and breakdown strength of an electrolytic capacitor of a power supply circuit for power failure and to reduce the cost and the space for a tape driving controller, by detecting the generation of a power failure during the tape travelling and switching the generated torque to make it smaller in the power failure mode than in the normal mode for both supply and take-up side reel motors. CONSTITUTION:A power failure is detected by a power failure detecting circuit 25, and the power supply of a control circuit is switched to the output of a power supply circuit 24 for power failure from that of a power supply circuit 23 for normal use by the 2nd switch circuit 26 and with the output of the circuit 25. At the same time, the detection values of supply and take-up side winding diameter detecting circuits 33 and 36 are held by the output of the circuit 25, and also the torque setting is switched to the power failure mode form the normal mode for supply and take-up side torque setting circuits 34 and 37. Thus the power supplies of supply and take-up side reel motors 7 and 8 are backed up for a magnetic tape 2 which is driven out with the rotational energy of a capstan 10 in case a power failure is produced during the tape traveling mode while the capstan 10 is in a press contact with a pinch roller 11. This eliminate the tape sag which is produced in a power failure mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tape drive control device for a video tape recorder or the like.

Conventional Structure and Its Problems FIG. 1 shows a schematic block diagram of a tape drive control device for a conventional cassette video tape recorder (hereinafter referred to as VTR).

In FIG. 1, 1 indicates a tape cassette, and 2 indicates a magnetic tape. Reference numerals 3 and 4 denote supply and take-up reel shafts of the VTR, which are adapted to engage with the supply and take-up reels 6.6 of the tape cassette 1. Reference numerals 7 and 8 are the supply side and take-up side reel motors. A rotary head cylinder 9 is provided with a pair of rotary magnetic heads. The magnetic tape 2 is wound around the rotating head cylinder 9 at an angle of about 180° and the video signal is recorded by the rotating magnetic head so as to form recording tracks oblique to the longitudinal direction of the magnetic tape. That's how it is played. 10
is a capstan, 11 is a pinch roller, and magnetic tape 2
is transferred at a predetermined speed by the pressure bond between the capstan 10 and the pinch roller 11. 12 is a full width erase head;
13 is an audio erase head, and 14 is an audio control head. Reference numeral 15 denotes a tape tension detector on the supply side, which is comprised of means for converting tape tension into an electrical signal. The output signal of the tape tension detector 15 is sent to the compensation circuit 16.
The output is passed through a filter at the first switch circuit 17.
is input. on the other hand.

The output from the supply side fixed torque generation circuit 18 is also input to the first switch circuit 17, and when the magnetic tape 2 runs from the supply side reel 5 to the take-up side reel 6 (hereinafter referred to as forward direction travel), the compensation circuit is inputted to the first switch circuit 17. 16 is selected, and when the magnetic tape 2 runs from the take-up reel 6 to the supply reel 5 (hereinafter referred to as reverse direction travel), the output of the supply side fixed torque generation circuit 18 is selected, and the output of the supply side reel 5 is selected. Motor drive circuit 2
0, and the output drives the supply reel motor 7, and is controlled so that the tape tension is constant when traveling in the forward direction, and a predetermined torque is generated in the supply reel motor 7 when traveling in the reverse direction. ing. On the other hand, on the first take-up side, the output of the take-up side fixed torque generation circuit 21 is input to the take-up side reel motor drive circuit 22, and the output drives the take-up side reel motor 8 during forward and reverse travel. At times, the take-up reel motor 8 is controlled to generate a predetermined torque. 23 is a power supply circuit for normal use, 24 is a power supply circuit for power outage, 25 is a power outage detection circuit, and 26 is a second switch circuit, and when a power outage occurs while the magnetic tape is running, the power outage detection circuit 25 is activated. detects a power outage, and based on the output thereof, the second switch circuit 26 switches the power supply of the control circuit from the output of the normal power supply circuit 23 to the output of the power supply circuit 24 for use during power outage. If a power outage occurs while the tape is running in the crimped state, the magnetic tape 2 is sent out by the rotational energy of the capstan 1o. We are trying to prevent the occurrence of chibutalumi.

According to the conventional example described above, if a power outage occurs while the magnetic tape is running (especially in the case of high-speed tape playback), the capstan 1
In order to wind the magnetic tape 2 sent out by pressure bonding between the magnetic tape 2 and the pinch roller 11 so as not to cause cracks, the withstand voltage and capacity of the electrolytic capacitor of the power supply circuit 24 for power outage must be extremely large, and the cost is high. Well, the problem is that it takes up a lot of space.

OBJECTS OF THE INVENTION The present invention is intended to solve these conventional problems, and aims to simplify a power supply circuit for power outage used when a power outage occurs during tape running.

Structure of the Invention The present invention detects a power outage when a power outage occurs during tape running, and switches the torque generated by the feed-side and take-up side rolling motors to be smaller at the time of a power outage than in normal times.
The present invention provides a tape drive control device that significantly reduces cost and space by reducing the capacity and withstand voltage of an electrolytic capacitor in a power supply circuit for power outages.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Second
The figure is a schematic configuration diagram of a tape drive control device for a cassette type VTR which is an embodiment of the present invention.

In FIG. 2, the same components as in FIG. 1 are designated by the same reference numerals.

The output signal of the tape tension detector 15 passes through a filter in a compensation circuit 16, and its output is input to a first switch circuit 17. On the other hand, the output of a supply-side reel frequency generator 31 (hereinafter referred to as supply-side reel FG) that detects rotation information of the supply-side reel motor 7 and the capstan frequency generator 32 (hereinafter referred to as a capstan) that detects rotation information of the capstan 10 FCi) is input into the supply side winding diameter detection circuit 33, and the diameter of the magnetic tape wound on the supply side reel is determined by the capstan PG signal present during one cycle of the output of the supply side reel FG31. It is determined by digitally counting the number of pulses. The output of the supply side winding diameter detection circuit 33 is input to the supply side torque setting circuit 34, which generates a signal that causes the supply side reel morph 7 to generate a torque proportional to the tape winding diameter of the supply side reel. It is input to the switch circuit 17, and when traveling in the forward direction, the output of the compensation circuit 16 is selected, and when traveling in the reverse direction, the output of the supply side torque setting circuit 34 is selected, and the output of the supply side reel motor 7 is driven. The tape tension is controlled to be constant when traveling in the forward direction and to a predetermined value also when traveling in the reverse direction.

On the other hand, on the second winding side, the output of the winding side reel frequency generator 35 (hereinafter referred to as winding side reel F'G) which detects the information on the 80 rotations of the winding side reel motor and the output of the capstan FG32 are connected to the winding side. The diameter of the magnetic tape wound on the take-up reel is input to the diameter detection circuit 36, and the number of pulses of the capstan FG signal present in one cycle of the take-up reel FG output is digitally counted. Seek by. The output of the winding diameter detection circuit 36 on the winding side is output from the winding side torque setting circuit 37.
A signal is input to the take-up reel motor 8 to generate a torque proportional to the tape winding diameter of the take-up reel, and its output is input to the take-up reel motor drive circuit 22, The side reel morph 8 is driven and the tape tension is controlled to a predetermined value even when traveling in the forward direction and in the reverse direction.

23 is a normal power supply circuit, 24 is a power supply circuit for power outage,
25 is a power outage detection circuit, and 26 is a second switch circuit. When a power outage occurs while the magnetic tape is running, the power outage detection circuit 25 detects the power outage, and the second switch circuit 26 uses the output from the power outage detection circuit 25 to detect the power outage. The power supply of the control circuit is switched from the output of the normal power supply circuit 23 to the output of the power supply circuit 24 for power outage.

At the same time, the output of the power failure detection circuit 25 holds the detection values of the supply side and take-up side winding diameter detection circuits 33 and 36, and changes the torque settings of the supply side and take-up side torque setting circuits 34. If a power outage occurs while the tape is running with the capstan 10 and pinch roller 11 pressed together, the magnetic tape 2 fed out by the rotational energy of the capstan 10 can be transferred to the reel motor 7 on the supply side and take-up side. By bank-up the power supply of 8, tape cracking will not occur during power outage.

In other words, even if the tape tension required for the magnetic tape during a power outage is reduced to a fraction of the normal tension, tape waling will not occur, so the winding diameter detection circuits 33 and 36 on the supply side and winding side hold the detected winding diameter value. , the supply side and the winding G (by setting the torque at the time of a power outage to a fraction of the normal time in the fill torque setting circuit 34.37, the supply side and winding side reel motor currents IM are T2KA, ILE □ (1) T:
Motor generated torque KA: According to the torque generation constant of the motor, during a power outage it is a fraction of the normal amount, and the motor voltage required for the supply side and take-up side reel motors 7.8 ■M is V, = RM, I , + KA″NK. (2
) Ra: Motor coil resistance KA: Mork power generation constant N6: Motor rotation speed can be lower during power outage compared to normal times.

Therefore, the electrolytic capacitor of the power supply circuit 24 for use during a power outage can have a small capacity and a low withstand voltage because the motor current and the motor voltage are reduced.

Effects of the Invention According to the present invention as described above, the electrolytic capacitor of the power supply circuit for power outage when a power outage occurs while the tape is running can be made to have a small capacity and a low withstand voltage, making it possible to reduce cost and space. It is.

[Brief explanation of drawings]

FIG. 1 is a block diagram of a conventional tape drive control device for a cassette-type VTR, and FIG. 2 is a block diagram of a tape drive control device for a cassette-type VTR according to an embodiment of the present invention. 1... Tape cassette, 2... Magnetic tape, 3... Supply side reel shaft, 4...
Take-up side reel shaft, 5... Supply side reel, 6...
...Take-up side reel, 7... Supply side reel motor, 8... Take-up side reel motor, 9...
...Rotating head cylinder, 10... Capstan, 11... Pinch roller, 12...
Full width erase head, 13...Audio erase head, 14...Audio control head,
15... Supply side tape tension detector, 16...
... Compensation circuit, 17 ... First switch circuit, 18 ... Supply side fixed torque generation circuit, 20.
...Supply side reel motor drive circuit, 21...
・Wind-up side fixed torque generation circuit, 22°. ...-Take-up side reel motor drive circuit, 23...
Normal power supply circuit, 24...Power supply circuit for power outage,
25... Power outage detection circuit, 26... Second
Switch circuit, 31... Supply side reel FG, 3
2... Capstan FG, 33... Supply side winding diameter detection circuit, 34... Supply side torque setting circuit, 36... Take-up side reel FC136 ...
...Rewinding side winding diameter detection circuit, 37...Rewinding side torque setting circuit. Name of agent: Patent attorney Toshio Nakao and 1 other person
1 Figure ■ m-” “- Word Figure 2

Claims (4)

[Claims] (1) A magnetic tape drive means for transporting the magnetic tape by pressure bonding between a capstan shaft and a pinch roller, a supply reel stand for mounting a supply reel for supplying the magnetic tape, and a take-up reel for winding the magnetic tape. A take-up reel stand to be attached, a supply reel motor that drives the supply reel stand, a take-up reel motor that drives the take-up reel stand, and a tape reel for winding on the tape reel of the supply reel stand. supply-side tape diameter detection means for detecting a signal corresponding to the diameter of the magnetic tape being wound; and a winding means for detecting a signal corresponding to the diameter of the magnetic tape wound on the tape reel of the winding-side reel stand. supply side and take-up side reel motor drive means having a side tape diameter detection means, a means for switching between normal torque and power failure torque according to outputs of the supply side and take-up side tape diameter detection means; The motor control circuit is equipped with a normal power supply and a power supply for use during a power outage, and in the event of a power outage, the output of the tape diameter detection means on the supply side and take-up side is held by the output of the power failure detection means, and the output of the tape diameter detection means on the supply side and take-up side is maintained. A tape drive control device characterized by switching a drive means to a power supply for power outages and switching a reel motor control circuit to a power supply for power outages. (2) The tape drive control device according to claim 1, wherein the reel motor generated torque according to the output of the tape diameter detection means is made smaller during a power outage than during normal times. (3) The tape drive control device according to claim 1, wherein the power supply voltage for driving the reel motor is lower during a power outage than during normal times. (4) The tape diameter detection means on the supply side receives the rotation information detection means of the capstan shaft and the output of the rotation information detection means of the supply reel stand, and the tape diameter detection means on the winding side receives the rotation information detection means of the capstan shaft. 2. The tape drive control device according to claim 1, wherein the output and the rotation information detection means output of the take-up reel stand are input, and each of them is constructed of a digital circuit.