JPH05109154A - Tape tension device - Google Patents

Abstract

PURPOSE:To surely control tension and relaxation of a band brake without changing a tape running position at the time of tape winding and quick feeding. CONSTITUTION:At the time of switching mode from a recording.reproducing state to a winding and quick feeding state, without moving a back tension arm 5 in order to release the back tension, a cam part 14b for controlling the band brake 4 is separately provided on an outer peripheral part of a back tension arm drive cam gear 14. A rotational plate 16 fixing an end part of the hitherto fixed side which is at the opposite side against a side being restrained to the back tension arm with the cam 14b, is rotated via a drive plate 17. Thus the tension relaxation of the band brake can be surely controlled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for optimally controlling the tape tension of a recording / reproducing apparatus using a magnetic tape such as a video tape recorder, a digital audio tape recorder, etc., and having a simple structure and stable performance. A tape tension control device is provided.

[0002]

2. Description of the Related Art Conventionally, as a tape tension device of this type, a band brake is interlocked with a back tension arm so that a band brake is wound around the cylindrical side surface of a magnetic tape running drive shaft to apply tension. Is common.

Details of this type of conventional tape tension device will be described with reference to FIGS. 4 and 5. FIG.

4 and 5 are plan views of a conventional tape tension device, FIG. 4 shows a state in which a braking force is applied to the drive shaft, and FIG. 5 shows a state in which the braking force is released. Shows. Referring to these drawings, in order to run a magnetic tape 8 wound on a reel (not shown) on the chassis 1, a part is formed in a cylindrical shape on a reel shaft 3 planted on the chassis 1. A drive shaft 2 having a side surface 2a is rotatably supported so that the reel can be fitted to the drive portion 2b. A band brake 4 having one end fixed to the chassis 1 by a mounting screw 12 or the like is in contact with the cylindrical side surface 2a of the drive shaft 2 so as to wind along the cylindrical side surface 2a.

The other end of the band brake 4 is a back tension arm 5 whose one end is rotatably supported by a tension arm shaft 13 planted in the chassis 1 and a guide provided on the back tension arm 5. It is attached to the pin 5a via a connecting arm 10 pivotally supported. Further, one end of a back tension spring 11 is attached to the back tension arm 5 for adjusting the tension of the band brake 4 contacting the drive shaft 2 by rotating the back tension arm 5.

Further, the connecting pin 6 planted in the back tension arm 5 is integrally formed with a cam gear 14 rotatably supported by a cam shaft 9 planted on the chassis 1 and a cam groove 14a. And is rotated by a predetermined angle in accordance with the rotation of the cam gear 14. The cam gear 14 is usually connected to a motor (not shown) for tape loading and mode switching via a gear train and rotated. Further, the back tension arm 5 is provided with a tension pole 7 which is in sliding contact with the magnetic tape 8 and detects the tension thereof.

In the back tension device thus constructed, the band brake 4 whose one end is fixed on the chassis 1 receives the force of the back tension spring 11 and the other end thereof rotates in the direction of arrow B to drive the drive shaft. The band brake 4 that is in contact with the cylindrical side surface 2a of 2 strongly slides to apply a constant force to the rotation of the drive portion 2b of the drive shaft 2.

Further, when the magnetic tape 8 wound on a reel (not shown) fitted with the drive unit 2b is delivered by the rotation of the drive unit 2b, the magnetic tape 8 comes into sliding contact with the tension pole 7 provided on the back tension arm 5. , Always run at a constant speed. When the amount of the magnetic tape 8 wound on the reel changes, the load changes, or the running state of the magnetic tape 8 changes, the balance between the rotation of the drive unit 2b and the running speed of the magnetic tape 8 is lost. The back tension, which is the tension in the direction opposite to the running direction of the magnetic tape 8, changes.

At this time, if the tension in the running direction of the magnetic tape 8 becomes strong, the tension pole 7 is rotated in the direction of arrow A by the tension of the magnetic tape 8 and is wound around the cylindrical side surface 2a of the drive shaft 2. The brake 4 is loosened, the rotational speed of the drive shaft 2 is increased, and the magnetic tape 8 is delivered faster than before. If the tension in the running direction of the magnetic tape 8 becomes weaker, the tension pole 7 is rotated in the direction of arrow B by the force of the back tension spring 11 stretched on the back tension arm 5, and the cylindrical side surface of the drive shaft 2 is rotated. Since the band brake 4 wound around 2a is tightened, the rotation speed of the drive shaft 2 is reduced, the delivery speed of the magnetic tape 8 is reduced, and a constant back tension is always applied to the magnetic tape 8. A stable tape running is always available.

In order to run the magnetic tape 8 at high speed during fast-forwarding and rewinding, for example, it is necessary to release the back tension device in order to reduce the running resistance of the tape. That is, the cam gear 14 is always rotated during the rewinding, fast-forwarding, stop and eject modes, and the cam groove 14a formed in the cam gear 14 is rotated, so that the back tension arm 5 engaged therewith is mechanically moved in the direction of arrow A. It has been necessary to loosen the band brake 4 by rotating the back tension arm 5 at a fixed position with the cam groove 14a.

However, when the back tension arm 5 is rotated in the direction of arrow A at this time, the tension pole 7 provided on the back tension arm 5 also moves largely, and the tension pole 7 separates from the magnetic tape 8. Become. Therefore, the running path of the magnetic tape is greatly different between when the magnetic tape 8 is run in this relaxed state and when the back tension device is not released.

Further, the movement of the back tension post 7 at the time of mode switching becomes large, so that the magnetic tape 8 is greatly loosened, or on the contrary, it is tensioned with excessive tension. Since the band brake 4 tends to extend straight, the band brake 4 is not completely separated from the drive shaft 2 and a variable load is applied to cause uneven rotation.

[0013]

As described above, in the conventional tape tension device, it is necessary to move the back tension arm in order to release the back tension device at the time of fast-forwarding and rewinding. Therefore, at the time of mode switching. The back tension post moves so much that the tape slackens, and conversely the tension becomes too tight, and due to the rigidity of the band brake, the band brake tries to extend straight, so There is a problem that the band brake is not completely released and a variable load is applied to the drive shaft to cause uneven rotation.

Therefore, the present invention is intended to solve the above problems, and provides a tape tension device capable of reliably controlling tension and relaxation of the hand brake without changing the tape traveling path. The purpose is to provide.

[0015]

A tape tension device of the present invention is provided with a back tension arm rotatably provided on a base member and a direction in which the back tension arm is pressed against a tape running by rotation of a drive shaft. A first urging means for urging, and a band brake having one end attached to the back tension arm so as to be pressed against the drive shaft when the back tension arm rotates in the tape pressing direction,
A cam gear having a first cam portion that is rotated according to operations such as recording / reproducing, rewinding, fast-forwarding, stopping, and ejecting the tape, and that is engaged with the back tension arm, and is rotatably provided on the base member. A first rotating member to which the other end of the band brake is attached, a second urging means for urging the first rotating member in the direction in which the band brake is in pressure contact with the drive shaft, and a rotatably rotatable base member. Is provided,
The cam member includes a second cam portion formed on the cam member and a second rotating member engaged with the first rotating member, and the first cam portion rewinds the cam member from a recording / reproducing position. Alternatively, the back tension arm is maintained at the tape pressing position when rotated to the fast-forward position, and the back tension arm is separated from the tape when the cam member is rotated to the eject position. Department is
When the cam member is rotated from the recording / reproducing position to the rewinding or fast-forwarding position, the first rotating member is rotated in the band brake relaxing direction via the second rotating member. Is characterized by.

[0016]

In the tape tension device having the above structure,
The first cam portion holds the back tension arm in the tape pressing position when the cam member is rotated from the recording / reproducing position to the rewind, fast forward, or stop position, and the cam member is rotated to the eject position. The back tension arm is formed so as to be separated from the tape when the cam member is rotated, and the second cam portion functions as the second rotation member when the cam member is rotated from the recording / reproducing position to the rewinding or fast-forwarding position. Since the first rotating member is formed so as to rotate in the band brake loosening direction, the back tension arm is kept at the tape pressing position during recording and reproduction,
Moreover, the tension of the band brake is controlled by rotationally displacing according to the tension of the magnetic tape. As a result, the braking force applied from the band brake to the drive shaft is controlled, and the back tension applied to the magnetic tape is kept constant. On the other hand, when the recording / playback state is switched to the tape rewinding or fast-forwarding state, the back tension arm is held at the tape pressing position, but the band brake is loosened by the rotation of the first rotating member, so that the drive shaft The braking force applied to was released. Therefore, the tape can be rewound or fast-forwarded at high speed. Also, record
The switching path between the playback state and the tape rewinding or fast-forwarding state does not significantly change the running path of the magnetic tape.Therefore, a large slack is generated in the magnetic tape, or conversely, it is stretched with excessive tension. Also, because of the rigidity of the band brake, the band brake tries to extend straight, so that the band brake does not completely separate from the drive shaft, and there is no problem such as uneven rotation due to variable load. . Further, since the back tension arm is separated from the magnetic tape at the time of ejection, the back tension arm does not get in the way when the cassette containing the magnetic tape is taken out.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIGS. 1, 2 and 3 are plan views showing an embodiment of a tape tensioning device of the present invention. FIG. 1 shows a state when a tension is applied to a drive shaft, and FIG. In the released state, FIG. 3 is a state explanatory view showing an intermediate process leading to the eject.

The same components as those in the conventional configuration shown in FIGS. 4 and 5 are designated by the same reference numerals.

Referring to these figures, in order to run a magnetic tape 8 wound on a reel (not shown) on the chassis 1, a reel shaft 3 planted on the chassis 1 is partially formed in a cylindrical shape. A drive shaft 2 having a side surface 2a formed therein is rotatably supported, and is configured so that it can be fitted to the reel by a drive portion 2b.

A tension pole 7 is erected on one end side of the surface of a back tension arm 5 rotatably supported by a tension arm shaft 13 planted in the chassis 1, and the tension pole 7 and the fulcrum are fulcrum. One end of a band brake 4 which is abutted so as to wind around the cylindrical side surface 2a of the drive shaft 2 is fixed to a connecting arm 10 rotatably attached to a guide pin 5a provided between the two. There is. Further, one end of a back tension spring 11 for adjusting the tension applied to the band brake 4 by rotating the back tension arm 5 in the direction of arrow B is attached to the other end side. Further, the connecting pin 6 planted in the back tension arm 5 is engaged with a cam groove 14a formed in a cam gear 14 rotatably supported by a cam shaft 9 planted on the chassis 1,
The back tension arm 5 is configured to rotate by a predetermined angle according to the rotation of the cam gear 14.

Next, the other end of the band brake 4 is fixed to a rotary plate 16 which is rotatably supported by a rotary plate shaft 15 which is erected on the chassis 1. Is arranged so as to be in sliding contact with the substantially semicircle of the cylindrical side surface portion 2a of the drive shaft 2. Further, one end of a rotating plate spring 19 for applying a biasing force in a direction of pressing the band brake 4 to the cylindrical side surface portion 2a of the drive shaft 2 is attached to the other end of the rotating plate 16. The drive plate 17 is rotatably supported by a drive plate shaft 18 provided upright on the chassis 1, and a connecting portion 17a provided on the drive plate shaft 18 is provided on a bending portion 16a provided on the rotating plate 16. It is configured to abut and to transmit rotation only in one direction. That is, the drive plate 17 is the drive plate shaft 18
The rotary plate 16 is rotated about the rotary plate shaft 15 in the direction of arrow D only when the rotary plate 16 is rotated about the rotary shaft in the direction of arrow C. In this way, the rotary plate 16 and the drive plate 17 can be interlocked.

In this embodiment, the mounting position of the other end of the band brake 4 with respect to the rotating plate 16 is the axis of the drive shaft 2 and the axis of the rotating shaft 15, which is the center of rotation of the rotating plate 16. Since it is set in the vicinity of the connecting straight line, when the rotating plate 16 rotates in the direction of arrow D, the other end (fixed end) of the band brake 4 is the cylindrical side surface portion 2 of the drive shaft 2.
It moves almost tangential to a. Therefore, the band brake 4 can be substantially evenly separated from the drive shaft 2 by a small movement of the rotating plate 16, and the rigidity of the band brake 4 causes the band brake 4 to extend straight so that the band brake 4 is completely removed. It is possible to compactly arrange these devices around the drive shaft 2 without causing the problem of not being separated.

The driving plate 17 has an engaging portion 17b provided on the driving plate 17, which is in contact with an outer peripheral cam portion 14b provided on the outer peripheral portion of the cam gear 14, so that the drive plate 17 is rotated by a predetermined angle by the rotation of the cam gear 14. Has been done.

The cam gear 14 is for tape loading,
Also, since it is configured to be connected to a motor (not shown) for switching each mode via a gear train so as to be rotated, rotation transmission is also reliable, and the rotation angle of the member engaged and rotated with this is also accurate. It can be controlled. Then, when the cam gear 14 rotates to a position where the tension pole 7 comes into contact with the magnetic tape 8 at a predetermined angle, the drive plate 17 and the rotating plate 16 interlocked with the drive plate 17 also rotate at a predetermined angle and the cylindrical side surface portion of the drive shaft 2 is rotated. 2a and band brake 4
It is configured so that and come into contact with each other to exert a predetermined tension, and
When the cam gear 14 is rotated a predetermined amount in the opposite direction from this position, the position of the tension pole 7 does not move substantially from this position, and only the drive plate 17 and the rotating plate 16 interlocking with this drive the tension of the band brake 4. The cam groove 14a provided on the cam gear 14 and the cam 14b provided on the outer peripheral portion of the cam gear are formed so as to rotate in the relaxing direction.

That is, the cam groove 14a of the prior art has the back tension arm 5 at the time of tape loading.
Is provided to separate the back tension arm 5 from the magnetic tape 8 when the tape is brought into contact with the magnetic tape 8 and at the time of rewinding, fast-forwarding, stopping, and ejecting. It is used only for contact and separation for ejecting.

With the above-mentioned structure, the tension pole 7 is rotated to a position where the back tension is detected, a predetermined amount of tension is applied to the drive shaft 2, and then fast-forwarding is performed.
When the tension needs to be released by rewinding or the like, it can be easily achieved by rotating the cam gear 14 by a predetermined amount in the direction opposite to the direction in which the tension is applied. Since it does not change, the tape running position does not change and stable running is obtained.

In this embodiment, the first cam portion is the cam groove formed in the cam gear, and the second cam portion is the outer shape cam formed in the outer peripheral portion of the cam gear.
The present invention is not limited to this, but the first cam portion may be the outer shape cam formed on the outer peripheral portion of the cam gear, and the second cam portion may be the cam groove formed on the cam gear. There is no problem if it is a structure that is performed.

[0028]

According to the present invention, when the mode is changed, the back tension arm is not moved to release the back tension, but another cam portion is formed on the outer peripheral portion of the cam gear for driving the back tension arm. On the side opposite to the side that is locked to the back tension arm by the cam,
Conventionally, by moving the side that was fixed, the running position of the magnetic tape etc. was not changed at all, and because the movement of the tension pole at the time of mode switching became large, the tape slackened, and conversely tensioned with excessive tension. There is no problem that the band brake will stay straight from the drive shaft due to the rigidity of the band brake and the band brake will not be completely separated from the drive shaft, giving a variable load to the drive shaft. This has the advantage that the tension and relaxation of the band brake can be reliably controlled.

Further, by providing a rotating plate for fixing one end of the band brake and a drive plate for driving the same, the operation direction of this fixed end can be made substantially tangential to the drive shaft, so that the band brake Because of the rigidity, the band brake tries to extend straight, and there is no problem that the band brake is not completely separated from the drive shaft and a variable load is applied to cause uneven rotation. Since it can be compactly arranged in the periphery, it also effectively works to reduce the size and weight of the entire recording / reproducing apparatus.

Further, since the back tension arm and the cam member for rotating the drive plate are driven by the gears, the rotation transmission is reliable without slip, and the control of the rotation angle is highly accurate and highly reliable. There is.

[Brief description of drawings]

FIG. 1 is a plan view showing an embodiment of a tape tension device of the present invention.

FIG. 2 is an operation explanatory view of the tape tension device shown in FIG.

FIG. 3 is an operation explanatory view of the tape tension device shown in FIG.

FIG. 4 is a plan view of a conventional tape tension device.

5 is an operation explanatory view of the tape tension device shown in FIG.

[Explanation of sign]

 1 chassis 2 drive shaft 2a cylindrical side face 2b drive unit 3 reel shaft 4 band brake 5 back tension arm 5a guide pin 6 connecting pin 7 tension pole 8 magnetic tape 9 camshaft 10 connecting arm 11 back tension spring 12 mounting screw 13 tension arm Shaft 14 Cam Gear 14a Cam Groove 14b Cam 15 Rotating Plate Shaft 16 Rotating Plate 16a Bending Part 17 Drive Plate 17a Connecting Portion 17b Engaging Part 18 Drive Plate Shaft 19 Rotating Plate Spring

Claims (1)

[Claims] 1. A back tension arm rotatably provided on a base member, a first urging means for urging the back tension arm in a direction in which the back tension arm is pressed against a tape running by rotation of a drive shaft, and a back tension. A band brake with one end attached to the back tension arm so that it is pressed against the drive shaft when the arm rotates in the tape pressing direction, and recording / reproducing, rewinding, fast-forwarding, stopping of tape,
A cam gear that has a first cam portion that is rotated in response to an operation such as ejecting and that engages with the back tension arm,
A first rotating member rotatably provided on the base member and having the other end of the band brake attached thereto, and a second attaching member for urging the first rotating member in a direction in which the band brake is pressed against the drive shaft. A first rotating member that is rotatably provided on the base member and is engaged with the second cam portion formed on the cam member and the first rotating member; The section keeps the back tension arm in the tape pressing position when the cam member is rewound from the recording / reproducing position, fast-forwarded, or rotated to the stop position, and
The back tension arm is formed so as to separate from the tape when the cam member is rotated to the eject position, and the second cam portion is such that the cam member rotates from the recording / reproducing position to the rewind, fast forward, or stop position. A tape tension device characterized in that it is formed so as to rotate the first rotating member in the band brake relaxing direction via the second rotating member when moved.