JPH081714B2 - Magnetic tape unit - Google Patents

Description

The present invention relates to an audio device or a magnetic tape device for driving a magnetic tape such as a VTR.

(Prior Art) In recent years, there has been an increasing demand for a magnetic tape device for driving a magnetic tape such as a VTR, which is required to be lower in price and higher in quality. It is expected to appear.

FIG. 4 is a plan view showing a VTR as an example of a conventional magnetic tape device.

In the figure, 1 is a capstan motor that is a drive source for feeding a magnetic tape (hereinafter, simply referred to as a tape), 2 is a capstan shaft, 3 is a pinch roller, and is constantly crimped to the capstan shaft 2 after completion of loading of the magnetic tape. ing. Four
Is a tape, 5 is a magnetic head cylinder, and 6 to 10 are so-called S-side tape guide members, which are an inclined post, a P2 post, a full erase head, a P1 post, and a tension post, respectively. The post 10 contacts the tape 4 at an intermediate position between the S reel base 18 and the cylinder 5 and controls the tape tension when the tape 4 is transported in the forward direction.

Further, 11 is a cassette tape, 12 is an S reel motor,
It is composed of a direct drive motor that also serves as the S reel base, and 13 is a T reel motor, which is smaller than the S reel motor 12 but has the same function.

With such a device configuration, the tape 4 is sent out in the forward or reverse direction by the capstan motor 1 and is wound by the T reel motor 13 or the S reel motor 12.

Now, when the driving mode in the reverse direction is changed, for example, from slow reproduction to static reproduction (hereinafter referred to as still), the capstan motor 1 is stopped first, and then the S reel motor 12 is stopped. In order to prevent the slack, the S reel motor 12 is always kept in a state where an appropriate tape winding torque is generated.

However, it is not possible to completely absorb the difference between the winding diameters of the two take-up reels in the cassette tape 11, and especially when the winding is performed on the S reel motor side with a small winding diameter.
The tape tension between the P2 post 7 and the full erase head 8 (hereinafter simply called tension) is 50 to 60.
There is gr, and this tension is a value at which the tape 4 is scratched at the magnetic head cylinder 5 or the video head is clogged or the like by still reproduction for several minutes.

Therefore, conventionally, after a certain time t, for example, t = 10 seconds has elapsed after the still reproduction, the tape 4 is once forwarded by one frame (one frame), and then the still mode is continued again.

Each of FIGS. 5 and 6 (A) shows the relationship of the frame advance by the feed position on the screen and the tension by the relationship with the feed position. Circled numbers indicate the still screen, the value when the first screen is intended as the still screen and is played back still, and the tape is fed forward one frame, and the tension is changed from slow backward play to still mode. It can be seen that it is reduced to about one-third at the maximum.

 FIG. 7 is a plan view showing another structure of the conventional example.

14 is a reel motor only for winding, 15 is a rolling contact idler, 16,1
Reference numeral 7 denotes an S-reel sensor and a T-reel sensor for detecting the rotation state of the reel stand 18 or 24, respectively. In this example, as in the conventional example shown in FIG. 4, when the reverse reproduction is started and the still reproduction is started, the capstan motor 1 and the reel motor 14 are first stopped in this order. At that time, the winding torque in the reverse slow reproduction until then is still applied to the S reel stand 18. If the winding torque generated by the reel motor 14 is constant, the tension changes depending on the tape winding diameter of the winding reel, and the difference between the maximum and minimum becomes three times or more,
For example, when the winding diameter on the S reel stand 18 side is small, the tension between the P2 post 7 and the full erase head 8 is generally 90.
Reach more than gr.

If such a sill state is continued for a long time, for example, for a few minutes, the magnetic head is clogged and its life is adversely affected. In order to prevent this, the above-described configuration is provided with reel sensors 16 and 17 on the reel stands 18 and 24 on both sides, detects the rotation state to determine the tape winding diameter in advance, and corresponds to the determined winding diameter. The winding torque of the reel motor 14 is controlled to adjust the tension condition and change range. In addition,
This adjustment is generally performed by changing the motor voltage stepwise.

Each of FIG. 5 and FIG. 6B shows the relationship between the feed position and the tension of the playback screen of the second conventional example described above, and the screen at the time of still is the intended screen. Is maintained, but the tension value has not decreased.

(Problems to be Solved by the Invention) In the first conventional example described above, the problem of tension when the backward reproduction mode such as the reverse slow or reverse search is changed to the still reproduction is almost solved, but t seconds Even after the lapse of time, the screen becomes a still image as shown in FIG. 5 (A), which is different from the screen that was originally intended to be still, and a problem may occur, for example, when performing high-precision video editing. There is also a structure for driving the reel base.
Since a single motor is required, including the control circuit results in a large cost, and it cannot be installed in a machine other than a high-class machine.

In addition, although there is no problem with the still screen obtained in the second conventional example, even if tension control is performed by determining the winding diameter,
In comparison with the first conventional example, the maximum variation is about twice as much, and the tension is still maintained in a high tension state. Further, in order to achieve low cost, generally, the winding diameter is discriminated and the reel motor winding is performed. Since the take-up torque is normally designed to be changed only once, the tension at the time of stillness in the winding diameter near the change point may have a higher value.

Although there is only one reel motor, it requires a reel sensor and control circuit to judge the tape winding diameter and change the winding torque, and also stabilizes the rotation in a wide range from slow to search. As a result, the cost is so high that it cannot be built into popular VTRs.

In view of the above-mentioned conventional problems, the present invention provides a still screen at the intended screen position when a still reproduction operation is performed from the reverse reproduction mode, and at a low cost that can be stably obtained without any tension problem. An object of the present invention is to provide a magnetic tape device configured.

(Means for Solving the Problems) The present invention is directed to the above-mentioned object in a magnetic tape recording / reproducing apparatus in which a cassette tape mounting means, a tape loading means, and a pinch roller are magnetically contacted to a capstan shaft at all times. Running means for transferring the tape in the forward direction and its reverse direction, and when the magnetic tape is transferred in the forward direction,
A still that has a tension control means for controlling the tape tension of at least a contact portion with the magnetic head cylinder in the magnetic tape, and that reproduces a still screen from the middle of reproduction in a reverse running mode for transferring the magnetic tape in the reverse direction. When the mode is set, after reproducing in the still mode for a certain period of time, the film is transferred in the reverse direction for a predetermined length, and again immediately in the forward direction for the same length as the reverse transfer, and again in the still reproduction mode. And achieve it as a configuration.

(Operation) According to the present invention having the above configuration, the still screen from the reverse slow or search playback mode can be stabilized at any intended position for a long time without affecting the tape or the magnetic head. It becomes possible to obtain it.

(Examples) Hereinafter, the present invention will be described in detail by examples with reference to the drawings.

FIG. 1 is a plan view showing an embodiment of the present invention together with a tape drive state. An outline arrow indicates reverse running of the tape, and an arrow different from that indicates a rotation direction of a drive member, and 19 is a capstan belt. The driving force of the capstan motor 1 is transmitted to the large limiter pulley 20, and at that time, the main rolling gear 21 is rotated in the same direction. 22 is an S idler gear that is always engaged with the S reel base 18, and 23
Is a T idler gear that is constantly engaged with the T reel base 24.

In this configuration, the main rolling gear 21 operates only during reproduction in the forward direction, for example, during PLAY or CUE, and in the reverse direction, the S idler gear cannot be rolled and cannot rotate due to the locking member. 25 is a reverse winding special motor that operates in reverse playback, reverse slow or reverse search, 26
Is a motor belt that drives a worm gear provided in close proximity. 27 is a relay pulley, 28 is a drive pulley with a small driving force
A drive belt transmitted to 29, 30 is a sub rolling gear, which is transferred to the S idler gear 22 at the time of reverse reproduction and transmits the drive torque from the reverse winding dedicated motor 25 to the S reel stand 18.
The winding torque at that time is constantly limited by the small limiter pulley 29, and the turning on / off of the driving force via the sub rolling gear 30 is performed by changing the rotation direction of the reverse winding dedicated motor 25. . For the explanation of other symbols, refer to No. 4.
The description of FIG. 5 and FIG. 5 is incorporated.

Generally, in the reverse tape reproduction, the tape tension value between the tape guide members on the head entry side of the magnetic head cylinder 5 has an important meaning for guaranteeing the function of this kind of tape device.

The tape device of the present invention configured as described above operates as follows.

First, regarding the device state when the tape is reproduced in the reverse direction from still reproduction, the sub rolling gear 30 is engaged with the S idler gear 22 to transmit the driving force from the reverse winding dedicated motor 25 to the S reel base 18. Then, the tape 4 transferred by the capstan motor 1 is wound with a constant winding torque.

The tension at that time naturally changes depending on the winding state of the tape 4 on the S reel table 18, and normally, a winding diameter difference of three times or more is generated from the winding start to the winding end. For example, the tension during reverse slow playback when the winding diameter of the S reel stand 18 is the minimum is 90 to 100 gr between the P2 post 7 and the full erase head 8.

When the still reproduction is performed from such a state, the sub rolling gear 30 stops while remaining in the S idler gear 22, so the tension of the tape is hardly lowered, and if the still state is continued, the tape may be damaged or the video head may be damaged. There is an adverse effect of causing clogging. Therefore, immediately after the still reproduction, the sub rolling contact gear 30 is set to S for the minimum required time.
After continuing the still while biting into the idler gear 22,
The tape 4 is once transferred in the reverse direction for one frame or one frame in the field, immediately returned to the normal direction, and then set to the still mode again. The operation in the still mode can be easily performed by controlling the reverse winding dedicated motor 25 and the capstan motor 1 using a microcomputer. The minimum time required from the still mode is 0.5 seconds in the case of the still slow reverse search or the reverse search in the case of this embodiment, and the still frame performed from an arbitrary intermittent frame feed using the job dial or the like. Then it was set to 3 seconds.

FIG. 2 shows the relationship between the screen feed positions of the above-described embodiment, and the still screen is represented by. As can be seen from this figure, if the still mode is set at the position of the screen during the reverse frame advance playback in the order of screen →→, the screen is temporarily displayed after t seconds, and the still reproduction of the screen again is continued. The above t seconds is the minimum necessary time immediately after the still mode described above is set.

FIG. 3 shows changes in the tension of the tape 4 corresponding to FIG. 2, and the tension remains high from immediately after the mode is switched to the completion of reverse frame feeding, but after one frame has been fed in the forward direction. In still mode, the maximum is about one fifth
It has been reduced to a stable tension.

It should be noted that the screen becomes "awkward" at the time of still, but it is only a moment in the normal still direction, and it is not a problem at all. Further, when the still mode is performed from the job mode, the screen certainly returns to the original state, but this is only for the first moment, and this is not a problem for the purpose of still reproduction for viewing a still image.

As described in detail above, the present invention is a magnetic tape device that allows a still screen from the reverse playback mode to be obtained accurately at the intended position and with stable tape tension.

(Effects of the Invention) As is apparent from the above description, according to the present invention, the still screen from the reverse playback mode can be reasonably obtained by the stable tape tension at the intended position, and the tension at that time can be restored. Since there is almost no difference in the winding diameter of the tape cassette at the time of stillness, there is an advantage that it is not necessary to perform troublesome tension control such as judgment of the winding diameter. Therefore, protection of the tape and clogging of the magnetic head are avoided. It is very useful for solving problems, and it is possible to use a winding-only motor that is cheap in structure and has a simple circuit. For example, the jog or shuttle function, which was traditionally provided only for high-end machines in terms of price, is generally used. It has many excellent effects, including being able to add it to popular machines.

[Brief description of drawings]

FIG. 1 is a plan view showing one embodiment of the present invention, FIG. 2 and FIG.
FIG. 4 is an operation characteristic diagram of the present invention, FIG. 4 is a plan view showing an example of a conventional magnetic tape device, FIGS. 5 and 6 are operation characteristic diagrams thereof, and FIG. 7 is another embodiment of the magnetic tape device. FIG. 1 ... Capstan motor, 2 ... Capstan shaft, 3
...... Pinch roller, 4 ... Magnetic tape, 5 ... Magnetic head cylinder, 6 ... Inclined post, 7 ... P2 post, 8 ...
… Full erase head, 9 …… P1 post, 10 …… Tension post, 11 …… Cassette tape, 12 …… S reel motor, 13 …… T reel motor, 14 …… Reel motor, 15
…… Rolling contact idler, 16 …… S reel sensor, 17 …… T reel sensor, 18 …… S reel stand, 19 …… Capstan belt, 20 …… Large limiter pulley, 21 …… Main rolling gear, 22 …… S idler gear, 23 …… T idler gear, 24
...... T reel stand, 25 …… Motor for reverse winding, 26 ……
Motor belt, 27 …… Relay pulley, 28 …… Drive belt,
29 …… Small limiter pulley, 30 …… Sub rolling gear.

Claims (1)

[Claims] 1. In a magnetic tape recording / reproducing apparatus, a cassette tape mounting means, a tape loading means, and a traveling means for transferring a magnetic tape in a forward direction and a reverse direction thereof while a pinch roller is constantly in pressure contact with a capstan shaft. And a tension control means for controlling the tape tension of at least the contact portion of the magnetic tape with the magnetic head cylinder when the magnetic tape is transferred in the forward direction, and the reverse running for transferring the magnetic tape in the reverse direction. In the mode, when the still mode is reproduced from the middle of the reproduction, after the reproduction in the still mode for a certain period of time, it has a transfer of a predetermined length in the reverse direction and immediately returns to the reverse direction in the forward direction. The magnetic tape device is characterized in that the same length as that of the above is transferred and the still reproduction mode is set again.