JPS6257151A - Reel turn table of magnetic recording and reproducing device - Google Patents

Abstract

PURPOSE:To obtain an optimum reel turn table rotational driving force by constituting the titled device so that a contact pressure against a clutch drum of a brake device becomes larger in an unloading mode than in a loading mode. CONSTITUTION:When a driving device is in a reverse reproducing mode, a capstan motor 9 is inverted, and a magnetic tape is run in the opposite direction. In such a case, an idler gear 11 is engaged to a clutch gear 24, a clutch force generated by a frictional felt 18 is transmitted to a supply reel turn table 15, and an optimum tape tension is supplied to a tape. Next, in case of an unloading operation for containing the tape into a cassette, from a state that the tape is drawn out of the cassette and is wound to the peripheral surface of a rotary drum, a clutch drum 26 is fixed, by which the clutch force works on the supply reel turn table 15 by a frictional felt 27 and the clutch drum 26. In such a case, the outside and the inside diameters of the felts 17, 27 are adjusted so that a contact pressure against the drum 26 of a brake device becomes larger in case of an unloading mode than in case of a loading mode.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a reel stand device used in a magnetic recording/reproducing device such as a video tape recorder, and particularly to a reel stand device configured to use the rotational force of a capstan motor to drive the reel stand. The present invention relates to a reel stand device for a magnetic recording/reproducing device.

2. Description of the Related Art A conventional magnetic recording and reproducing apparatus will be described with reference to FIGS. 7 to 9.

As is well known, in a magnetic recording and reproducing device such as a video tape recorder, a cassette 3 on which a magnetic tape 1 is wound or a tape 2 is built in is pulled out from inside the cassette 3 via each inner tape guide post 4, and a rotating head drum is used. It is configured to be wound helically around the circumferential surface of 5. 6 is an outer tape guide post erected on the substrate 19, and 7 is a tension regulator post.

When the device is switched to recording or playback mode.

A pinch roller 8 is pressed against a capstan shaft 10 of a capstan motor 9 that rotates counterclockwise at a predetermined speed, and is configured to run the magnetic tape 1 at a constant speed. Further, the clutch gear 14 of the take-up reel stand 13 is driven by the idler gear 11, so that the reel 2 on the take-up reel stand 13, which rotates with a light clutch friction force, is fed out by the capstan shaft 10 and the pinch roller 8. The magnetic tape 1 is wound up.

Next, the device switches to reverse playback mode.

The capstan motor 9 reverses and runs the magnetic tape 1 in the opposite direction. At this time, the idler gear 11 meshes with the clutch gear 16 of the supply reel stand 15 and transmits the clutch force generated by the friction felt 18 pressurized by the clutch spring 17 to the supply reel stand 15 to move the magnetic tape 1 onto the supply reel stand 15. 2.

Next, when the magnetic tape 1 wound around the rotary head drum 5 is stored in the cassette 3, the take-up reel stand 13 is fixed by a brake (not shown), and the capstan motor rotates clockwise. , as in the reverse playback mode, by winding the magnetic tape 1 onto the reel 2 on the supply reel stand 15 using the clutch force generated by the friction felt 18, each inner tape guide post 4 moves the cassette 3 along a predetermined path. This is to prevent the magnetic tenip 1 from sagging from the inner guide post 4 when moving into the opening.

In the FF/REV mode, the idler gear 11 is moved horizontally upward by an external drive (FIG. 8), and the gears formed on the take-up reel stand 13 and the supply reel stand 15 are engaged, and the capstan motor 9 is driven. It is configured to transmit force directly to the reel 2. In addition,
In FIG. 9, 20 is a reel shaft erected on the board 19;
2 is a reel hook that engages with the reel 2, and 22 is a reel cap against which the reel hook 21 is pressed by a reel hook spring 23.

Problems to be Solved by the Invention However, in the conventional configuration described above, in order to apply a desired tape tension to the magnetic tape 1 exiting the rotary head drum 5 during reverse playback, the clutch force of the supply reel stand 15 is
As in the tape running system shown in the figure, the head drum 5 rotates once.
In the case where there are many tape guide posts 4 and 6 before the magnetic tape 1 reaches the magnetic tape 1, it is necessary to set it above a certain value because of the tape running load caused by these tape guide posts. Furthermore, the clutch force for winding the magnetic tape 1 when storing it in the cassette 3 must be as light as possible, and the tape must be wound so as not to cause tape slack. If the magnetic tape was stored while being wound up with a clutch force suitable for reverse playback, there was a problem in that the tape would be damaged on the magnetic tape 1.Means for solving the problemTo solve the above problem. In order to achieve this, the present invention provides a reel stand that is rotatable around a reel shaft erected on a substrate and that can be engaged with one reel of a magnetic tape cassette;
It includes a first friction clutch means attached to the supply reel stand and a clutch drum to transmit the rotational driving force from the reel stand drive means to the reel stand, and is pressurized with the same urging force as the first friction clutch means. In the reverse playback mode, the second friction clutch means is separated from the clutch drum of the second friction clutch means, preferably attached to the reel stand, and in the loading mode, the magnetic tape is pulled out from the cassette, and the pulled out magnetic tape is moved into the cassette. a brake means that presses into contact with the second friction clutch drum in the unloading mode stored in the second friction clutch drum, and the brake means is configured such that the contact pressure of the brake means against the clutch drum is greater in the unloading mode than in the loading mode. A reel stand device for a magnetic recording and reproducing device is provided.

Operation According to the above configuration, in the reverse regeneration mode, the brake means is separated from the clutch drum of the second friction clutch means, so the rotational driving force from the reel stand drive means is applied to the brake via the first friction clutch. The winding force is transmitted to the supply reel stand without being subjected to any braking force by means, and a large winding force can be obtained. Also, in unloading mode,
Since the braking means is in contact with the clutch drum with the maximum pressing force, only the torque remaining after subtracting the large braking force transmitted via the second Hm clutch from the rotational driving force of the reel stand drive device is the first one. The winding force is transmitted to the reel stand via a friction clutch, and a relatively light winding force can be obtained. Furthermore, in the loading mode, the braking force by the brake means is reduced, so that a rotational driving force intermediate between the reverse playback mode and the unloading mode is transmitted to the reel stand. In other words, the optimum reel stand rotational driving force for each mode can be obtained purely mechanically.

EXAMPLE An example of the present invention will be described below with reference to FIGS. 1 to 6. Note that in this embodiment as well, the tape pass is the seventh one.
The same reference numerals are given to the same components as in FIGS. 7 to 9 among the structural members of this embodiment, and the explanation thereof will be omitted.

FIG. 1 shows a supply reel stand device, which is a main part of the present invention, in a vertical cross section.
The first friction felt 18 forms a first friction clutch means together with the first friction felt 18 . Furthermore, the clutch drum 26 is pressed against the second friction felt 27 by the clutch spring 17, forming a second friction clutch means. Note that 28 is a brake arm that applies braking force to the clutch drum 26 via a brake pad 31, and is pivotable about a brake rotation shaft 29 erected on the base plate 19, and 30 is a brake spring. (See also Figure 2).

FIG. 3 shows a reel stand driving device for driving the take-up reel stand 13 (FIGS. 7 and 8) or the supply reel stand 15. As shown in FIG.

In the figure, 32 is a transmission belt that transmits the rotational force of the capstan motor 9, and connects a capstan pulley 33 formed coaxially with the capstan shaft 11 and a relay pulley 34 formed coaxially with the relay gear 35. ing. The relay gear 35 meshes with another relay gear 36, and the center gear 12 coaxial with the relay gear 36 rotates the idler gear 11 supported on the idler arm 37. The idler arm 37 is configured so that the idler arm 37 selectively rotates depending on the rotational direction via a center clutch spring 39 and a center clutch 38 to drive the take-up reel stand 13 or the supply reel stand 15. There is. Further, during FF/REW, the idler arm 37 is moved upward by a drive device (not shown) as in the conventional example (FIG. 8).

Next, the operation of the device will be explained. When the device is switched to reverse playback mode, the capstan motor 9 reverses and runs the magnetic tape 1 (FIGS. 7 and 8) in the reverse direction. At this time, the idler gear 11 meshes with the clutch gear 24 shown in FIG. 1, and the clutch force T generated by the friction felt 18 constituting the first friction clutch means
1 is transmitted to the magnetic tape 15 to give the magnetic tape 1 optimum tape tension for reverse playback. At this time, the brake arm 28 is not acting on the clutch drum 26 by a release means (not shown).

As shown in FIG. 4, the outer diameter of the friction felt 18 is R1,
When the inner diameter is R2, the clutch force T1 is expressed as follows. Here, μ is the friction coefficient between the friction felt 18 and the clutch gear 24, and P is the load of the clutch spring 17.

Next, when performing an unloading operation in which the magnetic tape 1 is pulled out from the cassette 3 and wound around the circumferential surface of the rotary head drum 5 (FIG. 7), the magnetic tape 1 is stored in the cassette 3. The actuating release means (not shown) is released, and the brake pad 31 acts on the clutch drum 26.

This brake arm 28 is as shown in FIG.

When the magnetic tape 1 is rotated in the direction (counterclockwise) in which the magnetic tape 1 is wound onto the reel 2 on the supply reel stand 15, it is configured to bite. As shown in FIG. 6, the braking force T3 is determined by the drum diameter of the clutch drum 26 being R5, and the distance from the brake rotating shaft 29 of the brake arm 28 to the tangent and normal line at the brake contact point of the clutch drum 26, respectively. ,, When L, it is expressed as. Here, f is the pressure force with which the brake pad 31 is pressed against the clutch drum 26 by the brake spring 30, and μ' is the friction coefficient between the brake pad 31 and the clutch drum 266, so that T, = ω. The clutch drum 26 can be fixed.

By fixing the clutch drum 26 during unloading as described above, the clutch force T2 generated by the second friction felt 27 and the clutch drum 26, which constitute the second friction clutch means, acts on the supply reel stand 15. This clutch force T2 is expressed as T8. In addition, the fifth
As shown in the figure, R1 is the outer diameter of the second friction felt 27, and R4 is the inner diameter of the second friction felt 27.

Therefore, during the unloading operation, the supply reel stand 1
Reel 2 on top of 5 winds magnetic tape 1, and cassette 3
The torque when the clutches are stored inside is expressed by the equations ■ and ■.Since the respective clutch forces T1 and T2 are both generated by the same pressing force P (due to the clutch spring 17), the clutch forces of T□ and T2 are The difference is R,,R.

and R,,R,. Therefore, if T1<T, it is unlikely that this will happen in reality, and if the predetermined winding torque ('
rz 'rt) can be realized with high accuracy.

Next, when loading the magnetic tape 1 from inside the cassette 3, the brake arm 28 applies braking to the clutch drum 26 in the same way as when unloading.
Since the brake torque T4 at this time acts in the escape direction of the brake pad 31, no large torque is generated. T
4 is expressed as.

In the illustrated embodiment, the magnetic tape 1 is pulled out from the cassette on the supply reel stand 15 side with the take-up reel stand 13 locked (loading mode), and the magnetic tape 1 is stored in the cassette 3 (unloading mode). )
Therefore, double friction clutch means 18, 26, 27 and brake means 28 to 31 are provided on the supply reel stand 15 side, but the magnetic tape 1 is pulled out and stored on the take-up reel stand 13. When the winding is carried out on the side, such a mechanism is provided on the take-up reel stand 13 side. Also,
Reverse playback mode.

It is also possible to use other braking means in place of the illustrated braking means 28 to 31, as long as the braking force (including non-braking) can be changed according to mode changes such as loading mode and unloading mode. Needless to say, it is.

Effects of the Invention As described above, in the reel stand device of the magnetic recording and reproducing apparatus according to the present invention, by combining the double friction clutch means and the brake means, it is possible to obtain the optimum reel stand rotational driving force for each mode. This has an excellent effect.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a reel stand device according to an embodiment of the present invention, FIG. 2 is a plan view showing a brake means in the reel stand device, and FIG. 3 is a drive mechanism for the reel stand device. FIG. 4 is a plan view showing the friction felt in the first friction clutch of the reel stand device, FIG. 5 is a plan view showing the friction felt in the second friction clutch of the reel stand device, FIG. 6 is a plan view of the braking means showing the dimensional relationship for calculating the braking force in the reel stand device; FIG. 7 is a schematic plan view showing a conventional magnetic recording/reproducing device to which the present invention is applied; Figure 8 is a schematic front view showing the conventional reel stand device, and Figure 9 is the same reel stand device (
FIG. 1...magnetic tape, 2...reel, 3...cassette. 9... Capstan motor, 11... Idler gear, 12... Center gear, 13... Take-up reel stand, I5... Supply reel stand, 17... Clutch spring, 18.27...・Friction felt, 19... substrate,
20... Reel shaft, 24... Clutch gear, 26...
...Clutch drum, 28...Brake arm, 29
...Brake rotation axis, 30...Brake spring. 31...Brake pad, 32...Transmission belt, 3
3... Capstan pulley, 34... Relay pulley, 35.36... Relay gear, 37... Idler arm, 38... Center clutch agent Yoshihiro Morimoto Figure 1 Figure 2 7Figure 1Figure 1

Claims (1)

[Claims] 1. A reel stand that is rotatable around a reel shaft erected on a substrate and that can be engaged with one reel in a magnetic tape cassette, and a rotational driving force from a reel stand driving means is transmitted to this reel stand. The first one installed on the supply reel stand.
a friction clutch means and a clutch drum;
A second friction clutch means is attached to the reel stand to be pressurized with the same biasing force as the first friction clutch means, and in the reverse playback mode, the second friction clutch means is separated from the clutch drum of the second friction clutch means, and the magnetic tape is removed from the cassette. and a brake means that presses into contact with the second friction clutch drum in a loading mode for pulling out the magnetic tape and an unloading mode for storing the pulled-out magnetic tape in the cassette,
A reel stand device for a magnetic recording and reproducing apparatus, wherein the brake means is configured such that the contact pressure of the brake means against the clutch drum is greater in an unloading mode than in a loading mode.