JP2719399B2 - Magnetic recording / reproducing device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus in which a running direction of a magnetic tape can be freely switched between forward and reverse in a state where a magnetic tape is wound around a head cylinder to output an image. is there.

(Prior art) In a magnetic recording / reproducing apparatus (hereinafter referred to as VTR), when a video signal recorded on a tape is read by a rotating video head, the tape is sent at a constant speed and an appropriate tape tension is applied. Need to keep.

In the following description, forward travel of the tape means that the tape travels from the supply reel table side to the take-up reel table side via the head cylinder. In other words, the vehicle runs from the take-up reel table side to the supply reel table via the head cylinder.

In addition, the brake on the supply reel base does not act on the supply reel base in a fixed state, but applies soft braking.

To feed the tape at a constant speed, the tape is run by rotating the pinch roller while holding the tape between the capstan and the pinch roll, and when running the tape in the forward direction, a soft brake is applied to the supply reel base. In this case, a tape tension is applied to make the vehicle run.

To make the tape run in the reverse direction, the supply reel base is driven to rotate.At this time, if a brake is applied to the supply reel base, a large rotation torque is required. Means for releasing the brake on the platform has also been proposed (Japanese Utility Model Publication No. 61-25080).

Also, in the conventional VTR, when switching the running direction of the tape,
In general, in order to stabilize the running of the tape and to set the timing for switching the reel drive, the narrow pressure of the tape by the pinch roller and the capstan is released.

However, VTRs that have an editing function that quickly and accurately searches for playback images in frame units and that accurately sets the start and end points of recording on a tape require a capstan and pinch when switching the tape running direction. The tape must be held in a state where the tape is pressed between the roller and the roller.

These special VTRs require a dedicated motor for reel drive because it is necessary to adjust the timing between the tape feed of the capstan and the winding of the reel base when switching the tape running direction, and to prevent video signal loss due to tape slack. You are using

(Problem to be Solved by the Present Invention) As described above, a VTR having an editing function requires a dedicated motor for driving the reel base, which leads to an increase in cost.

In addition, when the running direction of the tape is switched, a deviation in the operation timing of the dedicated motor for driving the reel and the capstan motor, and a deviation in the timing of the braking operation to the supply reel base cause a great change in the tape tension, and the magnetic force applied to the tape is changed. There was a problem that the screen was disturbed due to poor contact of the head.

The present invention uses a method in which the capstan motor also functions as a motor for driving the reel base, and can switch the tape running direction while maintaining an appropriate tape tension while keeping the tape pressed between the capstan and the pinch roller. Another object of the present invention is to clarify a magnetic recording / reproducing apparatus which can make the tape tension during traveling in the forward direction and the traveling direction in the reverse direction of the tape as equal as possible.

(Means for Solving the Problems) A magnetic recording / reproducing apparatus according to the present invention comprises a chassis (1).
When the tape is rotatably mounted on the upper side and the tape held between the pinch roller (16) and the capstan (14) runs in the forward direction,
A supply reel base (12) that feeds the tape from the cassette and winds the tape in the reverse direction, and a capstan (1
4) The swing idler device (5) for transmitting the rotation power to the supply reel base (12), the brake band (41) wrapped around the supply reel base (12), and the base end pivotally connected to the chassis (1). The back tension lever has a back tension post (32) in contact with the tape at its free end, and urges the spring (34) in the tension direction of the brake band (41) to apply a rotational load to the supply reel base (12). (31), a brake release lever (42) pulling the other end of the brake band (41), and a brake tension lever (42) provided on the chassis (1) near the back tension lever (31). And a control plate (2) that slides on the chassis (1) and presses the brake release lever (42) to loosen the brake band (41) when the tape runs in the reverse direction.

The magnetic recording / reproducing apparatus is pivotally supported on the chassis (1) between the control plate (2) and the back tension lever (31), and the back tension lever (31) is positioned between the control plate (2) and the back tension lever (31). A spring (73) for urging the back tension lever (31) through the spring (73) is rotated by the control plate (2) when the tape runs in the reverse direction. Tensioning lever in the loosening direction of the tape (71), between the supply reel base (12) and the swing idler device (5), pivotally supported on the chassis (1), A relay gear (57) for transmitting the rotational power of the idler device (5) to the supply reel base (12); and a lock gear (47) overlapping the relay gear (57) and constituting a one-way clutch between the relay gear (57). 61) and provided on the control board (2) And a lock lever (63) that engages with the lock gear (61) during reverse rotation. When the tape reversely rotates, the rotation moment applied to the back tension lever (31) by the rotation of the back tension reduction lever (71) is , Smaller than the moment applied by the spring (34), the brake release lever (42)
By rotating the brake band (41) in the loosening direction, the back tension lever (31) rotates in the direction in which the back tension post (32) pulls the tape, and the lock lever (63) engages with the lock gear (61). The rotation of the relay gear (57) in the tape feeding direction is restricted, and only the rotation in the tape winding direction is allowed.

(Operation) When the tape T is traveling in the forward direction, the control plate (2) is separated from the brake band release lever (42) and the spring (43) for urging the lever in the direction of pulling the brake hand (No. FIG. 1, FIG. 5A).

The tension spring (34) for the back tension presses the tension lever (31) against the back tension post (32) on the tension lever (31) with a force to maintain an appropriate tape tension when the tape T runs in the forward direction. When the tape T is loosened, the tape T is drawn between the fixed guides (17) and (18) on the chassis to prevent the tape from loosening.

When the running direction of the tape T is switched from the forward direction to the reverse direction, the operation order of the brake device (4) is such that the control plate (2) projects on the control plate (2) while sliding toward the release lever (42). The provided first contact piece (25) acts on the brake release lever biasing spring (43) to put the release lever (42) in a free state (FIG. 5B). The back tension reducing lever (71) lowers the rotational moment of the back tension lever (31) in the tension applying direction via the spring (73).

Further, when the control plate (2) slides, the control plate (2)
The upper second contact piece (26) rotates the brake release lever (42) in a direction to loosen the brake band (41) (second
FIG. 5C).

 In this state, the switching of the tape running direction is completed.

The tape is sandwiched between the capstan (14) and the pinch roller (16), the tape is fed by the rotation of the capstan, and the supply reel table (12) and the take-up reel table (13) are moved by the capstan motor (15). VTR that also drives
In the mechanism, when the running direction of the tape T is switched, the timing of transmitting the rotational force is delayed by the time required for switching the drive system of the reel base.

Therefore, when the tape running direction is switched from the forward direction to the reverse direction, the tape T is loosened between the capstan (14) and the cylinder (11). At this time, as described above, the back tension post (32) acts on the tape T to eliminate the tape slack (FIG. 2).

When the tape is wound on the supply reel table side, the brake release lever (42) is pressed by the control plate (2) and rotates in the loosening direction of the brake band (41) as described above. And does not load the winding operation by the supply reel base (12).

When the running direction of the tape is switched from the reverse direction to the forward direction, the operation described above is reversed, and the control plate (2) moves away from the brake release lever (42) and the control plate (2).
Spring for brake release lever (43)
Is gradually applied to the release lever (42), and the release lever (42) gradually brakes the supply reel base (12).
It returns to the tape running state in the forward direction shown in the figure.

In the adjustment of the tape tension by the tension holding device, the tape tension when the tape runs in the reverse direction is:
It becomes stronger than the tape tension when the tape runs in the forward direction.

In the present invention, the back tension reducing lever (71) is rotated by the movement of the control plate (2) and the relay lever (74) when the running direction of the tape is switched from the forward direction to the reverse direction. Rotate the tension lever (31) in the direction to loosen the tension via (73). Thereby, the tension of the tape is weakened, and the strength of the tape tension due to the difference in the running direction of the tape can be reduced as much as possible.

(Embodiment) As an example of the present invention, a home magnetic recording / reproducing apparatus (hereinafter, referred to as VTR) generally known as a video will be described.

1 and 2 show the VTR mechanism from the top with the case removed. FIG. 1 shows the tape running in the forward direction, and FIG. 2 shows the tape running in the reverse direction. ing.

Head cylinder (11), supply reel stand (12), take-up reel stand (13), capstan (1)
4) Capstan motor (15) and pinch roller (1
6) is provided in a known manner, and a pair of tape leading guides (19) and (19a) are slidably provided between both sides of the head cylinder (11) and the supply reel table (12).

A swing idler device (5) and a supply reel table reverse rotation preventing device (6) are provided between the supply reel table (12) and the take-up reel table (13).

A control plate (2) is slidably mounted on the chassis (1) in parallel with an imaginary line L connecting the supply reel table (12) and the take-up reel table (13), and the control plate (2) is provided with an intermediate lever ( Two
1), first auxiliary control board (22) and second auxiliary control board (23)
The positive cam (24) is connected via the.

The supply reel table (12) has a band brake device (4)
The tape tension holding device (3) is connected to the band brake device (4).

Tape tension holding device (3) and control plate (2)
And a tape tension reducing device (7) is provided between them.

A tape cassette (not shown) is loaded across the supply reel table (12) and the take-up reel table (13).

The tape is pulled out of the tape cassette by the tape leading guide (19) (19a) and the head cylinder (11)
In each of the recording mode, normal playback mode, fast-forward playback mode, slow playback mode, and frame-by-frame playback mode, the tape runs in the forward direction.

In each of the reverse playback mode, the reverse fast forward playback mode, the reverse slow playback mode, and the reverse frame forward playback mode, the tape runs in the reverse direction.

When the running direction of the tape T is switched, the positive cam (24) rotates and the auxiliary control plates (22) and (23) and the intermediate lever (21)
Is operated, and the control plate (2) slides left and right in FIG.

By the sliding operation of the control plate (2), the swing idler device (5), the supply reel base reverse rotation preventing device (6),
The band brake device (4) to the supply reel table (12), the tape tension holding device (3), and the tape tension reducing device (7) operate.

In the VTR mechanism, the capstan motor (15) doubles as a drive motor for the supply reel table (12) and the take-up reel table (13).

Also, when the running direction of the tape T is switched in the recording and the various reproduction modes, the tape T runs while being pressed by the capstan (14) and the pinch roller (16).

 The configuration of each device will be described below together with the operation.

In the following description, each lever is provided rotatably on a plane parallel to the chassis (1).

Band brake device and tape tension holding device In FIG. 1, a back tension lever (31) and a brake release lever (42) between the lever and the control plate (2) are provided on the left side of the supply reel table (12). Brake band (41) deployed and spanned about half way around the supply reel base (12)
Is attached to the proximal end of the back tension lever (31), and the other end is attached to the free end of the brake release lever (42).

The back tension lever (31) rotates around the fulcrum (33), and is urged counterclockwise by a tension spring for back tension (34) to pull the brake band (41).

Brake release lever (42) is torsion spring (43)
, And is in contact with the stopper (45) on the chassis (1).

As shown in FIG. 5A, one end of the torsion spring (43) is inserted into the hole (10) of the chassis (1) and locked, and is wound around the fulcrum shaft (44) of the brake release lever (42). Penetrates the outside through a long hole (47) formed on the base end side of the lever.

When the tape T runs in the forward direction, the control plate (2) is separated from the brake release lever (42) and the torsion spring (43) (FIGS. 1 and 5A).

When the running direction of the tape T is switched from the forward direction to the reverse direction, the operation sequence of the brake device (4) is as follows: the control plate (2) slides to the left while the control device (2) protrudes from the left end of the control plate (2). One piece (25) pushes one end of the torsion spring (43) to release the brake release lever (42) (FIG. 5B).

Further, when the control plate (2) slides to the left, the second contact piece (26) on the control plate (2) directly presses the brake release lever (42) and pushes the lever (42) clockwise. Rotate to loosen the brake band (41) (FIG. 2, FIG.
Figure C). In this state, the switching of the tape running direction is completed.

The tension spring for back tension (34) is applied to the back tension post on the tension lever (31).
The tension lever (31) is urged in the counterclockwise direction by a force to maintain an appropriate tape tension when the tape T runs in the forward direction.
7) The tape T is pulled in between (18) and tension is applied to the tape.

With a VTR mechanism that also drives the supply reel table (12) and the take-up reel table (13) via the capstan motor (15) via the conventional swing idler device, the swing idler is used when the running direction of the tape T is switched. The timing of transmitting the rotational force is delayed by the swing operation of the device.

Therefore, when the tape running direction is switched from the forward direction to the reverse direction, the tape T is loosened between the capstan (14) and the cylinder (11). At this time, the back tension post (32) acts on the tape T to eliminate slack in the tape T (FIG. 2).

FIG. 6 shows the relationship of the force acting on the back tension lever (31) when the tape is in the forward direction. The tape running state in the forward direction includes a counterclockwise moment Msp due to the load Fsp of the tension spring (34) for back tension,
The clockwise moment Mt due to the tape tension Ft, and the force applied by the back tension brake bant (41)
A clockwise moment Mb by Fb acts on the back tension lever (31).

At this time, the back tension lever (31) is in a fishing state, and the following equation is established.

Mt + Mb = Msp The brake release lever (42) to which one end of the back tension brake band (41) is attached
The conditional expression when it is pressed to 5) and becomes fixed is as follows.

Fto> Fb / e ^μθ Fto is generated by the torsion spring (43), μ is the coefficient of friction between the back tension brake band (41) and the supply reel base (12), and θ is the wrap angle with respect to the supply reel base Is represented.

By appropriately setting the load of the torsion spring (43), when the tape tension Ft becomes extremely small, the condition for fixing the brake release lever (42) is broken, and Fto <Fb / e ^μθ , Brake release lever (4
2) operates, and the back tension lever (31) also rotates in the tape direction, so that an appropriate tension can be applied to the tape.

When the tape T is wound on the supply reel table side, as described above, the brake release lever (42) is pressed by the control plate (2) and rotates in the loosening direction of the brake band (41). The brake is hardly used, and does not load the winding operation by the supply reel base (12).

When the running direction of the tape is switched from the reverse direction to the forward direction, the operation described above is reversed, and the control plate (2) moves away from the brake release lever (42) and the control plate (2).
In response to the return operation, the urging force of the torsion spring acts on the release lever (42), which gradually rotates counterclockwise to gradually brake the supply reel base (12),
It returns to the tape running state in the forward direction shown in FIG.

As described above, the spring release lever (42)
Momentary counterclockwise rotation of the back tension lever (3) via the brake band (41).
1) does not suddenly rotate clockwise, so that extreme slack in the tape can be prevented, and screen disturbance due to poor contact of the magnetic head with the tape can be prevented.

Back tension reducing device It is desirable that the tension of the tape is the same in the forward running direction and in the reverse running direction.However, in the adjustment of the tape tension by the tension holding device, when the tape runs in the reverse direction, The tape tension when traveling in the reverse direction is stronger than the tape tension when traveling in the opposite direction.

The back tension reducing device works in cooperation with the tape tension driving device to make the tension in the forward traveling direction and the reverse traveling direction of the tape as equal as possible.

Below the chassis (1), a back tension reducing lever (71) and a relay lever (74), each formed in a substantially V shape, are provided between the tension lever (31) and the control plate (2). The two levers (71) and (74) operate in conjunction with the slide of the control plate (2).

As shown in FIG. 9, the tension reducing lever (71) rotates about a fulcrum (72), and the first free end (77a) and the tension lever (31) are connected by a tension spring (73). ing.

The spring connecting piece (31a) of the tension lever (31) is bent downward and penetrates a long hole (1a) opened in the chassis (1) as shown in FIG. The spring (73) is hooked on the connecting piece (31a).

On the transition path in the counterclockwise direction of the second free end (77b) of the tension reducing lever (71), the tension lever (31)
Spring connection piece (31a) is located.

The first free end (79a) of the relay lever (74) has a pin (7
6) is protruded, and the pin is slidably fitted in a through-hole (70) opened near the rotation fulcrum (72) of the tension reducing lever (71).

The second free end (79b) of the relay lever (74) has a protruding shaft (7
8) protrudes, and the protruding shaft (78) extends through the through-hole (1b) of the chassis (1) shown in FIG.

On the control plate (2), a first shaft (78) of the relay lever (74) is pushed to rotate the lever clockwise in the first direction.
A cam surface (27a) and a second cam surface (27b) protruding higher than the first cam surface are formed on the left side of the first cam surface.

When the tape T travels in the forward direction, as shown in FIG. 1, the protruding shaft (78) of the relay lever (74) moves between the first cam surface (27a) and the second cam surface (27b) of the control plate (2). It fits in the recess between them.

In the above state, the back tension reducing spring (73) has a free length, and the back tension reducing device (7).
Does not affect tape tension.

When the running direction of the tape is switched from the forward direction to the reverse direction, by sliding the control plate (2) to the left, the protruding shaft (78) of the relay lever (74) of the tension reducing device (7) is moved to the control plate ( 2) Ride on the first cam surface (27a) and fulcrum (7
Rotating clockwise around 5), the back tension reducing lever (71) rotates counterclockwise around the fulcrum (72), as shown by the chain line in FIG.

At this time, the back tension reducing spring (73) is stretched, and the stretching force of the spring acts against the tension spring (34) of the back tension lever (31), and the back tension post (32) is attached to the tape T. Weakens the force acting on

The force of the back tension reducing spring (73) is, as shown by the dashed line in FIG. 9, when the reducing lever (71) is rotated counterclockwise to extend the spring, as shown in FIG. Corresponds to the clockwise moment Mb due to the force Fb pulled by the brake band (41).

As described for the tape tension holding device,
When the tape is traveling in the forward direction, Msp = Mt + Mb is always satisfied, and the tape is given a substantially constant tension. However, when the traveling direction of the tape is switched from the forward direction to the reverse direction, the left and right sides of the control plate (2) are changed. Direction, the brake release lever (42) rotates clockwise, and the brake band (4
1) loosen.

Since the brake band (41) is loosened, Fb = 0∴Mb = 0, and Msp> Mt. However, as described above, the tension lever (31) responds to the slack of the brake band and the back tension reducing spring (73). The clockwise force (Mb) due to) is working. Therefore, the back tension lever (31) has approximately Msp'-Mb (where Msp 'is the fulcrum (33) of the back tension lever (31) due to the spring force when Msp is weakened by the back tension reducing spring (73). The moment of (circumferential moment) is always working, the tape slack can be absorbed at any time, and the brake hand (41) releases the supply reel base (12), so that the tape can be wound with a small torque.

In the unloading operation of the tape for storing the tape wound around the cylinder (11) in a cassette (not shown) on the reel base, the control plate (2) slides to the right as shown in FIG. The projecting shaft (78) of (74) rides on the second cam surface (27b), and the lever (74) is largely rotated clockwise. As a result, the back tension reducing lever (71) pivots largely counterclockwise,
1) The second free end (77b) is the back tension lever (3
1), the back tension lever (31) is rotated clockwise about the fulcrum (33), and the free end of the lever (31) is moved to the tape leading guide ( Located on the transition road of 19a).

While the tape leading guide (19a) is moving toward the reel base, the back tension lever (31) is pressed, and the back tension lever (31) is clocked to a position where it does not hinder the tape T from being stored in the tape cassette. (Fig. 4).

Swing Idler Apparatus As shown in FIG. 7, the swing idler apparatus (5) is provided with a swing lever (51) between a supply reel table (12) and a take-up reel table (13). Reel stand and lever (51)
The relay gals (57) and (58) are deployed between them.

An idler gear (53) is provided on the swing lever (51), and the idler gear (53) is provided with gear rotation transmitting means (5).
9) and the capstan motor (1
It is linked to 5).

By switching between forward and reverse rotation of the capstan motor (15), a rotational friction force acts between the swing lever (51) and the idler gear (53), and the lever swings around the fulcrum (52). In operation, the idler gear (53) selectively meshes with the two relay gears (57) and (58), and the supply reel base (1
2) Or take-up reel (13) is driven to rotate in the take-up direction.

As shown in FIGS. 7 and 8, a leaf spring (55) is attached to the swing lever (51), and the leaf spring (55) has a base end fixed to the swing lever (51) and a free end idler. It faces the gear mounting side.

A protruding piece (56) is formed to be bent upward at the end of the idler gear of the swing lever (51).

The distance between the projecting piece (56) of the oscillating lever (51) and the rotation fulcrum (52) of the lever is equal to the free end of the leaf spring (55) and the lever (5).
It is longer than the distance between the fulcrum (52) of 1).

The control plate (2) has a first projection (28a) and a second projection (28) which can be engaged with the leaf spring (55) and the projection (56).
b) is bent upward.

FIG. 1 shows the state of the swing idler device (5) when the tape T is running in the forward direction. The swing lever (5) is tilted toward the take-up reel table (13), and the idler gear (53) is wound. It engages with the relay gear (58) on the reel base.

The first projection (28a) of the control plate (2) is connected to the swing lever (5
The projection (56) of 1) and the second projection (28b) of the control plate (2) are immediately before contact with the leaf spring (55).

When the running direction of the tape T switches from the forward direction to the reverse direction, the capstan motor (15) temporarily stops, and during this time, the control plate (2) slides to the left. At this time, the first projection (28a) of the control plate (2) is connected to the projection (5) of the swing lever (51).
Press 6) to forcibly rotate the swing lever (51) clockwise.

Thus, the idler gear (53) is separated from the relay gear (58) on the take-up reel base (13). At this time, the second protrusion (28b) of the control plate (2) also presses the leaf spring (55).

The distance between the projecting piece (56) of the oscillating lever (51) and the pivot (52) of the lever is determined by the distance between the free end of the leaf spring (55) and the lever (5).
Since the swing lever (51) is rotated clockwise since the distance from the pivot point (52) of (1) is longer, the protruding piece (56) is immediately moved to the first projection (1) of the control plate (2). 28a), the second protrusion (28b) of the control plate (2) keeps pushing the leaf spring (55) alone, and the oscillating lever (51) rotates clockwise (seventh).
Figure).

Further, the control plate (2) slides to the left, the swing lever (51) continues to rotate clockwise, and the idler gear (5)
3) meshes with the relay gear (57) on the supply reel base side (FIG. 2).

The oscillating lever (51) receives a clockwise rotational force via the leaf spring (55). If the idler gear (53) and the relay gear (57) are engaged with each other, the leaf spring (55) is Since it flexes and absorbs shock, it does not damage the teeth.

By a series of operations of the swing idler device (5),
Upon completion of the switching of the tape T to the reverse running mode,
The idler gear (53) and the relay gear (57) are securely engaged, and the capstan motor (1) is connected to the supply reel base (12).
The rotation of 5) can be transmitted, and the tape T can be run in the reverse direction and wound on the supply reel table (12).

As described above, when the running direction of the tape is switched from the forward direction to the reverse direction, the swinging lever (51) is controlled by the control plate (2).
Forcibly rotates clockwise, even if the idler gear (53) and the relay gear (58) on the take-up reel base side are strongly engaged, the meshing can be quickly released, and the idler gear ( The meshing between the 53) and the relay gear (57) on the supply reel table side can be performed without forcing through the leaf spring (55).

When the running direction of the tape T is switched from the reverse direction to the forward direction, the control plate (2) slides rightward before the rotation direction of the capstan motor (15) is switched.

Therefore, the projection (56) of the leaf spring (55) and the swing lever (51) does not collide with the first projection (28a) and the second projection (28b) of the control plate (2).

Also, when switching from the reverse running to the forward running, the swing lever (51) rotates counterclockwise from the state shown in FIG. 2 and the idler gear (53) is moved to the take-up reel base (13) side. The take-up timing is delayed during this time, and the tape T is loosened between the capstan (14) and the take-up reel base (13). )
And the pinch roller (16), the tape is not loosened on the cylinder (11) side, so that the video signal is not lost.

In switching between modes not related to recording and reproduction, such as the fast forward / rewind mode, the stop mode, and the eject mode, the control plate (2) operates on the right side when traveling in the forward direction in FIG. 2) The first projection (28a) and the second projection (28b) do not affect the swing lever (51), and the swing lever (51) transmits the rotational torque of the capstan motor (15) as before. Perform a normal swing motion.

In addition, a rubber idler may be used instead of the idler gear, and a relay roller may be used instead of the relay gear, and the rotational force can be transmitted by friction between the rubber idler and the relay roller.

Supply reel base reverse rotation prevention device On the relay gear (57) on the side of the supply reel base (12), a lock gear (61) is provided coaxially with the gear. A one-way clutch (not shown) is interposed between the lock gear (61) and the relay gear (57).
In the state where 1) is locked, the relay gear (57) is allowed to rotate clockwise, but is prevented from rotating counterclockwise.

The control plate (2) is provided with a lock lever (63) as a means for locking the lock gear (61).

The lock lever (63) has a base end pivotally supported by the control plate (2), and has a lock claw (65) protruding from a free end facing the lock gear (61) at a free end thereof. A spring plate (67) protrudes from the base end, and a contact portion (66) protrudes from the distal end of the spring plate.

On the chassis (1), a pin (64) is protrudingly provided on the left side of the contact portion (66).

When the running of the tape T is switched from the forward direction to the reverse direction, the contact portion (66) of the lock lever (65) is moved to the pin (64) by the operation of sliding the control plate (2) to the left as shown in FIG.
As a result, the lock lever (63) rotates clockwise, and the lock claw (65) engages with the lock gear (61) to lock the lock gear.

Since the lock claw (65) is biased toward the lock gear (61) via the spring plate (67), no excessive force is applied when the lock lever (63) and the lock gear (61) are engaged.

As described above, when the running direction of the tape T shifts from the forward direction to the reverse direction and after the shift, the lock gear (61)
In this state, as described above, the relay gear (57) on the supply reel base (12) is allowed to rotate only in the clockwise direction, and is prevented from rotating in the counterclockwise direction. Accordingly, the supply reel table (12) engaged with the relay gear (57) rotates counterclockwise, that is, in the tape T winding direction, but rotates clockwise, that is, the tape T is rotated from the supply reel table side. Rotation in the pulling-out direction is prevented.

Thereby, as described above, the slack of the tape that occurs when the running direction of the tape is switched from the forward direction to the reverse direction,
When the tape is pulled between the guides (17) and (18) and absorbed by the rotation of the tension lever (31), the tape is not pulled out from the tape supply reel table side.

(Effect) When the running direction of the tape shifts from the normal direction to the reverse direction,
Loosen the back tension brake band (41) with respect to the supply reel base (12), and use the back tension lever (31).
Can temporarily pull the tape,
The tape slack caused by the switching of the tape running direction can be eliminated. Accordingly, the tape running direction is switched while the pinch roller (16) is pressed against the capstan (14) by an inexpensive method in which the reel stand is also driven by the capstan motor (15), and an appropriate method is adopted. The mode can be shifted while maintaining the tape tension.

Further, when the running direction of the tape is switched from the forward direction to the reverse direction, the movement of the control plate (2) and the relay lever (74) rotates the back tension reducing lever (71). ) Via the tension lever (3
1) Rotate in the direction to loosen the tension. Thereby, the tension of the tape is weakened, and the strength of the tape tension due to the difference in the running direction of the tape can be reduced as much as possible.

Also, when the running direction of the tape shifts from the reverse direction to the forward direction, the tape does not separate from the back tension lever (31), and problems such as screen disturbance due to a large change in the tape tension can be solved.

The present invention is not limited to the configuration of the above embodiment,
Various modifications are possible within the scope described in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of the VTR mechanism in the forward running state of the tape, FIG. 2 is a plan view of the same tape in the reverse running state, and FIG. FIG. 4 is a plan view of FIG. 4 when tape unloading is completed, FIG. 5A, FIG. 5B, and FIG. FIG. 7 is a plan view of the tape tension holding device, FIG. 7 is a plan view of the idler device, FIG. 8 is a perspective view of a main part of the oscillating lever and the control plate, and FIG. 9 and FIG. FIG. (12) ... take-up reel stand (13) ... supply reel stand (2) ... control plate (4) ... brake device (5) ... swing idler device (6) ... supply reel stand Reverse rotation prevention device (7) Back tension reduction device

 ──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-56848 (JP, A) JP-A-62-117738 (JP, U) JP-A-62-133238 (JP, U) JP-A-59 74548 (JP, U)

Claims (2)

(57) [Claims] A rotatably mounted chassis (1),
A supply reel table (12) for feeding the tape out of the cassette when the tape held between the pinch roller (16) and the capstan (14) travels in the forward direction and winding the tape during the reverse travel, and a capstan (14). ), A swing idler device (5) for transmitting the rotating power to the supply reel table (12), a brake band (41) wound around the supply reel table (12), and a base end pivotally supported by the chassis (1). The back tension lever (32) having a back tension post (32) in contact with the tape at its free end, biasing the brake band (41) in the tension direction with a spring (34), and applying a rotational load to the supply reel base (12). 31), a brake release lever (42) pulling the other end of the brake band (41), and a brake tension lever (31) provided on the chassis (1) near the back tension lever (31).
Each time the tape running direction is changed, the tape slides on the chassis (1), and when the tape runs in the reverse direction, the brake release lever (42)
Control plate (2) to release the brake band (41) by pressing
In the magnetic recording / reproducing apparatus comprising: a control plate (2) and a back tension lever (31) pivotally supported on the chassis (1); A spring (73) for urging the back tension lever (31) in the tension releasing direction is stretched,
When the tape runs in the reverse direction, the tape is rotated by being driven by the control plate (2), and the back tension lever (3) is driven through the spring (73).
1) a back tension reducing lever (71) for urging the tape in the tape loosening direction, and a pivot support on the chassis (1) between the supply reel base (12) and the oscillating idler device (5); A relay gear (57) for transmitting the rotational power of the swing idler device (5) to the supply reel table (12), and a lock that overlaps the relay gear (57) and forms a one-way clutch between the relay gear (57). A gear (61), and a lock lever (63) provided on the control plate (2) and engaged with the lock gear (61) during reverse rotation of the tape.
Back tension lever (3
The rotation moment of 1) is smaller than the moment given by the spring (34), and the rotation of the brake release lever (42) in the loosening direction of the brake band (41) causes the back tension lever (31) to rotate the back tension post ( Three
2) rotates in the direction of pulling the tape, and by the engagement of the lock lever (63) and the lock gear (61),
A magnetic recording / reproducing apparatus characterized in that rotation of the relay gear (57) in the tape feeding direction is restricted, and only rotation in the tape winding direction is permitted. 2. When the tape is unloaded, the back tension reducing lever (71) directly pushes the back tension lever (31), and the free end of the lever moves to the tape leading guide (19).
2. The magnetic recording / reproducing apparatus according to claim 1, wherein the magnetic recording / reproducing apparatus is rotated until it is positioned on the transition path of a).