JP2001084668A - Magnetic recording/reproducing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably stop a tape without causing a tape damage even when power supply is interrupted while FFing/REWing in a magnetic recording/ reproducing device. SOLUTION: The interruption of an AC power source is detected by an AC power source interruption detective circuit 21, and a micro-computer 19 receives the detection signal, and reduces a running speed of a magnetic tape 3 while controlling a reel motor 10 until a DC power source from a DC power source circuit 10 is fallen, and sufficiently reduces the running speed of the magnetic tape 3 until the DC power source is fallen, and brake pads 24, 25 are brought into contact with reel bases 22, 23 to start the braking, and the tape damage due to the braking is reduced, and the tape is stopped stably.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder.

[0002]

2. Description of the Related Art FIG. 3 is a schematic diagram showing a conventional video tape recorder. In FIG.
It is wound around the drum 6 via the guide posts 4 and 5 and is supplied or wound by the supply-side reel 1 and the take-up reel 2.

A supply reel 1 and a take-up reel 2
Are fitted on upper portions of a supply-side reel base 22 and a take-up reel base 23, which are driven to rotate by the supply-side reel motor 9 and the take-up reel motor 10, respectively. The frequency signal generators (FG) 11 and 12
A sine wave signal having a frequency corresponding to the rotation speed of each of the reel motors 9 and 10 is generated, and the waveform is shaped into a pulse signal (FG signal) by the waveform shaping circuits 17 and 18 and then supplied to the microcomputer 190.

[0004] Brake pads 24, 25 for applying a braking force by contacting the reel bases 22, 23 are driven by solenoids 7, 8.
Are driven through the drive circuits 13 and 14 by a drive command signal from the microcomputer 190. DC power supply circuit 20
Generates each DC power supply from the AC power supply and supplies it to each circuit block.

When an FF (fast-forward) or REW (rewind) command is received according to a mode command signal, the microcomputer 190 generates a FF signal based on the FG signal from the waveform shaping circuits 17 and 18.
The rotation speed of the take-up reel motor 10 is controlled via the drive circuit 16 so that the running speed of the magnetic tape 3 becomes constant. Further, the displacement of the magnet 28 attached to the lever on which the movable post 26 is erected is measured by the magnetic sensor 2.
The torque of the supply-side reel motor 9 is controlled via the drive circuit 15 so that the tension of the magnetic tape 3 becomes constant. At the time of FF, the magnetic tape 3 is wound around the take-up reel 2, and at the time of REW, the magnetic tape 3 is wound around the supply reel 1.

While the magnetic tape 3 is running, the solenoids 7, 8
Are operating on the suction side, and the brake pad 2
4 and 25 are controlled so as not to contact the respective reel bases 22 and 23.

When a power failure occurs in the AC power supply during the FF / REW mode, the DC power supply circuit 2 based on the AC power supply
0, the supply of the DC power supplied to each circuit block is also cut off.
The drive of the brake pad 10 is also stopped, but is rotating at a high speed due to inertia. On the other hand, when the solenoids 7 and 8 operate to the return side due to the cutoff of the DC power, the brake pad 2 is driven.
4 and 25 come into contact with the reel bases 22 and 23, and the frictional force exerts a braking force on the reel motors 9 and 10, so that the running speed of the magnetic tape 3 is suddenly reduced and stopped.

[0008]

In such a conventional magnetic recording / reproducing apparatus, when the amount of magnetic tape wound on the reel is largely different between the supply side and the take-up side, or the supply side and the take-up side have irregularities. If there is a difference in the friction force of the brake pad on the winding side, or if the friction force of the brake pad changes significantly due to the operating environment such as ambient temperature, When the braking force is not balanced and the magnetic tape is stopped due to a power failure in the FF / REW mode, the magnetic tape may be greatly slackened or may be strongly stretched to cause tape damage.

Such tape damage is remarkable in the case of a power failure in the FF / REW mode in which the running speed of the magnetic tape is fast, but also occurs in the case of a power failure in a normal recording / reproducing mode.

[0010] The present invention has been made in view of the above points, and has as its object to reduce tape damage caused by a power failure occurring while a magnetic tape is running.

[0011]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention provides a DC power supply circuit for generating a DC power supply to each section from an AC power supply, and a first and a second, which wind or supply a magnetic tape. A reel, a braking means for braking the first and second reels when DC power from the DC power supply circuit is stopped, a power cutoff detecting circuit for detecting cutoff of AC power, and a magnetic tape Speed control means for controlling the running speed of the magnetic tape in response to a detection output of the power cut-off detection circuit in the running mode of the magnetic tape.

Thus, if a power failure occurs and the AC power is cut off while the magnetic tape such as FF / REW is running, the running speed of the magnetic tape is reduced. The running speed of the magnetic tape can be reduced before the DC power supply is stopped and the braking of the first and second reels is started, the tape damage due to the braking is reduced, and the magnetic tape becomes loose or strong. The magnetic tape can be stopped stably without stretching.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is a digital signal generator for generating DC power to be supplied to each section from AC power.
C power supply circuit, first and second reels for winding or supplying a magnetic tape, and braking for braking the first and second reels when the DC power supply from the DC power supply circuit is stopped. Means, a power cutoff detecting circuit for detecting a cutoff of AC power, and a speed control means for controlling a running speed of the magnetic tape, wherein the speed control means detects the power cutoff circuit in a running mode of the magnetic tape. The running speed of the magnetic tape is reduced in response to the output. If the AC power is cut off due to a power failure, the running speed of the magnetic tape is reduced. The running speed of the magnetic tape can be reduced before the braking of the first and second reels is started after the braking is stopped, so that tape damage due to the braking can be reduced. That.

Here, the running mode refers to a mode in which the magnetic tape runs, and includes a recording mode, a reproducing mode, a fast-forward mode, a rewind mode, and the like.

According to a second aspect of the present invention, the running mode is a fast-forward / rewind mode, and the speed control means controls a reel drive motor for driving the first and second reels, thereby controlling a magnetic field. In addition to controlling the running speed of the tape, the running speed of the magnetic tape is reduced in response to the detection output of the power cutoff detection circuit in the fast forward / rewind mode. In the fast-forward / rewind mode in which the tape damage at the time of the stop due to the interruption of the power supply is large, the effect of reducing the tape damage becomes remarkable.

According to a third aspect of the present invention, the speed control means makes the deceleration in response to the detection output faster than a normal deceleration for shifting from the traveling mode to the stop mode. From when the DC power is no longer supplied to the braking means until braking of the first and second reels is started, the running speed of the magnetic tape can be sufficiently reduced, and tape damage due to braking can be further reduced. You can do it.

According to a fourth aspect of the present invention, the power supply cutoff detection circuit provides a detection output corresponding to the presence or absence of AC power supply cutoff, and the speed control means includes a first power supply corresponding to AC power supply cutoff. When the second detection output corresponding to the return of the AC power from the power cut-off detection circuit is given during the deceleration in which the traveling speed of the magnetic tape is decelerated in response to the detection output of In this case, the running speed of the magnetic tape is maintained, and in the case of an instantaneous interruption of the AC power supply for a short time such that the supply of DC power to the braking means is not interrupted, the running speed is maintained at a reduced speed. Therefore, it becomes easier to respond to the next mode command as compared with the case where the vehicle is accelerated to the original traveling speed.

According to a fifth aspect of the present invention, the power supply cutoff detection circuit provides a detection output corresponding to the presence or absence of AC power supply cutoff, and the speed control means includes a first power supply cutoff corresponding to AC power supply cutoff. When the second detection output corresponding to the return of the AC power from the power cut-off detection circuit is given during the deceleration in which the traveling speed of the magnetic tape is reduced in response to the detection output of Is accelerated to return to the original set speed, and in the case of momentary interruption of AC power supply for a short time such that the supply of DC power to the braking means is not interrupted, the state immediately returns to exactly the same state as before the momentary interruption. Can be done.

Hereinafter, an embodiment of the present invention will be described with reference to FIG.
This will be described with reference to FIG.

FIG. 1 is a block diagram showing a schematic configuration of a video tape recorder as a magnetic recording / reproducing apparatus according to one embodiment of the present invention. In FIG. Assign a sign.

In FIG. 1, a magnetic tape 3 is wound around a drum 6 via guide posts 4 and 5, and is first and second
The reel is supplied or wound by the supply-side reel 1 and the take-up reel 2 as reels.

Supply side reel 1 and take-up side reel 2
Are fitted on upper portions of a supply-side reel base 22 and a take-up reel base 23, which are driven to rotate by the supply-side reel motor 9 and the take-up reel motor 10, respectively. The frequency signal generators (FG) 11 and 12
A sine wave signal having a frequency corresponding to the rotation speed of each of the reel motors 9 and 10 is generated, and the waveform is shaped into a pulse signal (FG signal) by the waveform shaping circuits 17 and 18, and then applied to a microcomputer 19 that controls each section. Can be

Brake pads 24 and 25 for applying a braking force by contacting the respective reel bases 22 and 23 are driven by solenoids 7 and 8, and these solenoids 7, 8
Are driven through drive circuits 13 and 14 by a drive command signal from a microcomputer 19. DC power supply circuit 20
Generates each DC power supply from the AC power supply and supplies it to each circuit block.

When the FF or REW command is received by the mode command signal, the microcomputer 19 causes the waveform shaping circuits 17 and 18 to operate.
The speed of the take-up reel motor 10 is controlled via the drive circuit 16 so that the running speed of the magnetic tape 3 becomes constant, based on the FG signal from the CPU. Also, the displacement of a magnet 28 attached to a lever on which the movable post 26 is erected is detected by a magnetic sensor 29 and taken in from an A / D input of the microcomputer 19 so that the tension of the magnetic tape 3 is kept constant. The torque of the supply-side reel motor 9 is controlled via a drive circuit 15. At the time of FF,
The magnetic tape 3 is taken up on the take-up reel 2 and
At the time of EW, the magnetic tape 3 is wound around the supply reel 1.

While the magnetic tape 3 is running, the solenoids 7, 8
Are excited to operate on the suction side, and are controlled so that the brake pads 24 and 25 do not contact the reel bases 22 and 23. The driving circuits 13 and 14, the solenoids 7 and 8, and the brake pads 24 and 25 constitute braking means for braking the supply-side reel 1 and the take-up reel 2 via the respective reel bases 22 and 23. When the supply of DC power from the DC power supply circuit 20 is cut off after about 100 ms, for example, after the AC power supply is cut off due to a power failure, the solenoids 7, 8 operate to the return side, and the brake pads 24, 25 are moved to the reel base. The reel motors 9 and 10 are brought into contact with the reel motors 22 and 23 to exert braking force on the reel motors 9 and 10 by the frictional force. The time delay of about 100 ms is determined by the capacity of a capacitor used in the DC power supply circuit 20 and the like.

The above configuration is the same as that of the conventional example shown in FIG.

In this embodiment, in the FF / REW mode, the AC power supply is cut off due to a power failure, and
When the power is cut off, the supply of DC power from the DC power supply circuit 20 to each circuit block is cut off, and the solenoids 7, 8
By operating on the return side, the brake pads 24, 2
5 is a reel base 22, 2 which rotates at a high speed due to inertia.
In order to reduce tape damage of the magnetic tape 3 when the brake is brought into contact with the magnetic tape 3 and braked, the magnetic tape 3 is configured as follows.

That is, in this embodiment, there is provided an AC power cutoff detecting circuit 21 which detects the presence or absence of AC power cutoff and provides a corresponding output, and the detected output of the AC power cutoff detecting circuit 21 is magnetic. It is provided to a microcomputer 19 having a function as speed control means for controlling the running speed of the tape 3.

The AC power supply cutoff detection circuit 21 compares the level of the DC voltage obtained by rectifying the AC input with the reference level and, when the level is equal to or higher than the reference level, determines that the AC power supply has not been cut off and gives a high level detection output. , When it is less than the reference level, it is determined that the AC power supply has been cut off and a low-level detection output is given.

In the FF / REW mode, when the microcomputer 19 having a function as a speed control means receives a low-level detection output corresponding to AC power cutoff from the AC power cutoff detection circuit 21, the microcomputer 19 responds thereto. 3
To reduce the traveling speed of the
The DC power is turned off after the C power is cut off and the brake pad 2
The running speed of the magnetic tape 3 is reduced until the braking of the reel bases 22 and 23 is started by the steps 4 and 25 to reduce tape damage due to the braking.

The deceleration process by the microcomputer 19 can be realized, for example, by decreasing the speed target value of the take-up reel motor 10 by a fixed amount every 5 ms.
The deceleration slope (rate of deceleration) at this time may be set to a normal deceleration slope when stopping from FF / REW,
Although a steep deceleration slope may be set, the steep deceleration slope is preferable in order to reduce tape damage.

FIG. 2 is a timing chart showing the operation of the present embodiment when the AC power supply is cut off due to a power failure during FF / REW.
DC voltage obtained by rectifying AC power in the C power cutoff detection circuit 21, (b) detection output of the AC power cutoff detection circuit 21, (c) DC power supply from the DC power supply circuit, and (d) running of the magnetic tape 3. (E) shows the drive voltage applied to the solenoid 7, and (f) shows the drive voltage applied to the solenoid 8.

[0033] As shown in FIG.
The level of the rectified output of the power supply is about 70%, which is the reference level.
Then, the AC power cutoff detection circuit 21 provides a low-level detection output as a first detection output corresponding to the cutoff of the AC power, as shown in FIG.
Upon receiving this detection output, the microcomputer 19 sets the magnetic tape 3
Is reduced as shown in FIG.
About 100 ms later, the voltage level of the DC power supplied to each circuit block decreases as shown in FIG. As a result, the drive voltage supplied to the solenoids 7 and 8 also decreases as shown in FIGS. 7E and 7F, and the solenoids 7 and 8 perform a return operation, and the brake pads 24 and 2
5 comes into contact with each of the reel bases 22 and 23, and a braking force acts on each of the reel motors 9 and 10 by the frictional force.
The traveling speed of the vehicle rapidly decreases from the middle.

As described above, when the AC power is cut off due to the power failure, the running speed of the magnetic tape 3 is reduced. Therefore, the DC power is cut off after the AC power is cut off, and the solenoids 7, 8 return. Brake pads 24, 2
5, the running speed of the magnetic tape 3 can be reduced until the running speed of the magnetic tape 3 is reduced.
Can be reduced, and the magnetic tape 3 can be stably stopped without the magnetic tape 3 being loosened or strongly stretched.

It is to be noted that the AC power supply may be restored while the running speed of the magnetic tape 3 is being reduced in response to the low-level detection output as the first detection output corresponding to the interruption of the AC power supply. In the case of a momentary power failure, when a high-level detection output as a second detection output corresponding to the return of the AC power is supplied from the AC power cutoff detection circuit 21, the microcomputer 19 stops deceleration and reduces the traveling speed at that time. It may be maintained so that the mode can be promptly shifted to the next mode command, or the vehicle is driven to stop deceleration and return to the original FF / REW set speed, that is, the FF / REW state before the momentary stop. The speed may be increased.

In the above-described embodiment, the description has been given of an example in which the control means is constituted by a microcomputer. However, the control means can be similarly implemented by a hardware circuit such as a gate array or a PLD.

In the above-described embodiment, the running speed of the magnetic tape is reduced in response to the interruption of the AC power in any of the FF mode and the REW mode.
Only in one of the FF and REW modes, the running speed of the magnetic tape may be reduced in response to the interruption of the AC power.

In a running mode other than FF / REW, that is, in the recording mode and the reproducing mode, when the interruption of the AC power is detected, the running speed of the magnetic tape may be reduced. In this case, the running speed of the magnetic tape may be reduced by controlling the capstan motor to control the rotation of the capstan.

The braking means is not limited to the one in which the brake pad is pressed against the reel base and the braking is performed by the frictional force as described above, and the braking means may be decelerated by using a gear or the like to perform the braking. .

Although the above embodiment has been described with reference to a video tape recorder, the present invention is not limited to a video tape recorder, but may be applied to other magnetic recording and reproducing devices such as an audio tape recorder.

[0041]

As described above, according to the present invention, in the magnetic tape running mode such as fast-forward or rewind, if the AC power is cut off due to a power failure, the running speed of the magnetic tape is reduced. From the interruption of the first to the start of braking of the first and second reels by the braking means.
The running speed of the magnetic tape can be reduced, so that tape damage due to braking can be reduced as compared with the conventional example in which braking is performed without deceleration when the AC power is cut off.

[Brief description of the drawings]

FIG. 1 is a block diagram of a magnetic recording and reproducing apparatus according to an embodiment of the present invention.

FIG. 2 is a timing chart of the embodiment of FIG.

FIG. 3 is a block diagram of a conventional example.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 supply reel 2 take-up reel 3 magnetic tape 11, 12 frequency signal generator 19 microcomputer 21 AC power cutoff detection circuit 22 supply-side reel stand 23 take-up reel stand

Claims (5)

[Claims] 1. A DC power supply circuit for generating a DC power supply to each section from an AC power supply, first and second reels for winding or supplying a magnetic tape, and a DC power supply from the DC power supply circuit. When it is gone, the first,
A braking means for braking the second reel, a power cutoff detecting circuit for detecting interruption of AC power, and a speed control means for controlling a running speed of the magnetic tape; Wherein the traveling speed of the magnetic tape is reduced in response to the detection output of the power cutoff detection circuit. 2. The running mode is a fast-forward / rewind mode, and the speed control means controls a running speed of a magnetic tape by controlling a reel drive motor that drives the first and second reels. 2. The magnetic recording / reproducing apparatus according to claim 1, further comprising reducing a traveling speed of the magnetic tape in response to a detection output of the power cutoff detection circuit in a fast-forward / rewind mode. 3. The magnetic recording / reproducing apparatus according to claim 1, wherein the speed control means performs a deceleration in response to the detection output faster than a normal deceleration for shifting from a running mode to a stop mode. 4. The power supply cutoff detection circuit provides a detection output corresponding to the presence or absence of AC power supply cutoff, and the speed control means responds to a first detection output corresponding to the AC power supply cutoff. If the second detection output corresponding to the return of the AC power from the power cut-off detection circuit is given during the deceleration of the running speed of the magnetic tape, the deceleration is stopped and the running speed of the magnetic tape at that time is stopped. Claim 1 that maintains
4. The magnetic recording / reproducing apparatus according to any one of items 3 to 3. 5. The power cutoff detection circuit provides a detection output corresponding to the presence or absence of AC power cutoff, and the speed control means responds to a first detection output corresponding to AC power cutoff. During the deceleration of the running speed of the magnetic tape, when a second detection output corresponding to the return of the AC power from the power cut-off detection circuit is given, the running speed of the magnetic tape is accelerated to the original setting. 4. The magnetic recording / reproducing device according to claim 1, wherein the speed is returned to the speed.