JPH0731380Y2 - Magnetic recording / reproducing device - Google Patents

Description

TECHNICAL FIELD The present invention relates to a magnetic recording / reproducing apparatus such as a video tape recorder (hereinafter referred to as VTR).

2. Description of the Related Art As a conventional tape cassette mounting portion of this type of magnetic recording / reproducing apparatus, there is known one having a structure as shown in FIGS. 3 and 4, for example.

Hereinafter, referring to the drawings, 1 is a supply-side reel stand,
Reference numeral 2 is a take-up reel stand on which a pair of reels of a tape cassette (not shown) are fitted and mounted on the small-diameter portions 1a, 2a of the reel stands 1, 2. The reel bases 1 and 2 are supported and rotated by drive shafts 3 and 4 of a drive motor (not shown). In the figure, an arrow A indicates a rotating direction in the case of playing and fast-forwarding, and an arrow B indicates a rotating direction in the case of rewinding the tape. The tape of the tape cassette is as thin as about 20 μm, but one roll is about 250 m, and the weight is about 250 g, and even if a stop signal is issued to stop during play and fast forward, the tape, It takes time to stop due to the inertia of the motor. In general, as a countermeasure, many are equipped with a mechanical braking function as well as an electromagnetic brake to improve stopping accuracy. The amount of tape on both reel stands 1 and 2 changes with the passage of time for recording and playback. That is, the amount of tape on the left side (supply side) in the drawing is large around the beginning of recording and reproduction, and the amount of tape on the right side (winding side) in the drawing around the end is large. Therefore, depending on the timing of stop, the inertia on the supply side and the take-up side differs, and it takes extra time to stop the tape with a large amount of tape remaining. I may go out to. Therefore, in order not to damage the tape, it is necessary to stop the tapes on the supply side and the winding side almost at the same time.

Therefore, a mechanical braking function as shown in the drawing is provided. In the figure, 5 is a brake arm that abuts on the outer circumference of the large-diameter portion 1b of the supply-side reel stand 1 for braking, and 6 is a brake that abuts on the outer circumference of the large-diameter portion 2b of the take-up reel stand 2 for braking. On the arms, both brake arms 5 and 6 are pivoted on central pivots 7 and 8, respectively. Further, brake shoes 9 and 10 are provided at one ends of both brake arms 5 and 6 so as to be in pressure contact with the outer peripheral surfaces of the large diameter portions 1b and 2b. A fibrous felt is generally used for the brake shoes 9 and 10. Reference numeral 11 denotes a spring interposed between the other ends of both brake arms 5 and 6, in a direction in which the other ends of the brake arms 5 and 6 approach each other, that is, the brake shoes 9 and 10 on the one end side have the large diameter portions 1b and 2b. Is urged in the direction approaching the outer peripheral surface (direction of arrows C and D in FIG. 3).
Reference numeral 12 denotes an electromagnetic solenoid provided so as to face the vicinity of the other end of the brake arm 6, and an operating piece 12a of the electromagnetic solenoid 12 pushes the vicinity of the other end of the brake arm 6 against the force of the spring 11. As a result, the brake arm 6 rotates in the direction of arrow F in FIG. 4, and the brake shoe 10 on one end side moves away from the outer circumference of the large diameter portion 2b of the take-up reel stand 2, and at the same time, the brake arm 6 causes the brake arm 5 to move. When pressed, the brake shoe 9 rotates in the direction of arrow E in FIG. 4, and the brake shoe 9 on the one end side is separated from the outer periphery of the large diameter portion 1b of the supply reel stand 1. FIG. 3 shows a state where the brake shoes 9 and 10 are pressed against the outer peripheral surfaces of the large-diameter portions 1b and 2b to apply a brake, and FIG. 4 shows that the electromagnetic solenoid 12 works to cause the brake shoes 9 and 10 to operate. It shows a state in which the brake is released by separating from the outer peripheral surfaces of the large diameter portions 1b and 2b.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention In the above-mentioned configuration, the brake is applied by the force of the spring 11, but since the fibrous felt is used for the brake shoes 9 and 10, the braking force is reduced to the temperature. There was the problem of ever changing things. Also, brake shoe 9,
No. 10 is a chemical fiber felt having a large coefficient of friction, which is generally used as described above, but the chemical fiber becomes softer as the temperature rises, resulting in an increase in brake friction. FIG. 5 shows an enlarged view of the relationship between the reel base large diameter portion 13 and the brake shoe 15 at one end of the brake arm 14 when the temperature is about 40 ° C., and the reel base large diameter portion 13 rotates in the direction of arrow G in the figure. In this case, since the brake shoe 15 becomes softer, the brake shoe 15 is embedded in the outer periphery of the large-diameter portion 13 and the braking force increases. As shown in FIG. 6, the brake torque is optimally designed in the shaded area. There was a problem that it was out of the range of values. If the braking force becomes larger than the designed value and suddenly stopped while the tape is running, the tape will be overstretched and stretched, or it will be loosened and the tape will be wound into the mechanism and the tape will be damaged. I got it.

The present invention solves such a problem, and an object thereof is to set the brake torque within a predetermined design value range at a high temperature.

Means for Solving the Problems In order to solve this problem, the present invention is designed so that a brake shoe provided at one end of a brake arm is brought into contact with the outer peripheral surface of a reel stand to brake the rotation of the reel stand. In the recording / reproducing apparatus, a protrusion is provided at one end of the brake arm with a protrusion amount slightly smaller than the thickness of the brake shoe.

Effect With this configuration, even if the brake shoe is soft at high temperature and tries to bite into the large diameter portion of the reel stand, a protrusion is provided at one end of the brake arm. It is possible to prevent contact with the outer peripheral surface and prevent further deformation of the brake shoe. As a result, the braking force can be kept within the optimum design value range from low temperature to high temperature, and as a result, the tape will stretch even if it is suddenly stopped while the tape is running, or it will be loosened too much and the tape will be caught in the mechanism. It is possible to prevent the tape from being damaged.

Embodiment An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, reference numeral 16 is a protrusion provided on one end of the brake arm 17 so as to protrude toward the reel base large diameter portion 18 side, and 19 is a brake made of a felt made of chemical fiber attached to one end of the brake arm 17. It's a chew. The brake shoe 19 is provided with a thickness slightly larger than the amount of protrusion of the protrusion 16 in advance. With such a simple structure, the braking force at high temperature is set within the range of the optimum design value, and its operation will be described below.

In FIG. 1, when the reel base large-diameter portion 18 is rotating in the direction of arrow H, the brake arm 17 can rotate around the support shaft as described in the above-mentioned conventional example.
Even if 19 is soft at high temperature, a predetermined braking force can be obtained without biting into the large diameter portion 18 of the reel stand. Also, when the reel base large diameter portion 18 is rotating in the direction of arrow I, the brake shoe 19 tries to bite into the reel base large diameter portion 18 by being soft at high temperature. Since the projecting portion 16 is provided at the end, the tip of the projecting portion 16 abuts on the outer peripheral surface of the reel base large-diameter portion 18, and further biting deformation of the brake shoe 19 can be prevented. Therefore, as shown in FIG. 2, from the time when the temperature rises around 40 ° C., the braking force can maintain a constant state within the optimum design value range.

The reason why the brake arm 17 is slightly inclined with respect to the tangential direction of the large diameter portion 18 of the reel stand is to slightly shift the stop time of both reel stands when the tape is stopped so that the tape in the stopped state can be stretched appropriately. is there.

As described above, according to the present invention, at temperatures other than high temperature, the braking force within the range of the optimum design value is obtained by the brake shoe, and at high temperature, the protrusion contacts the outer peripheral surface of the large diameter portion of the reel stand. Since the brake shoes can be in contact with each other and deformation of the brake shoes can be limited, the braking force can be maintained within the range of the optimum design value. As a result, the tape stretches even when it is suddenly stopped while the tape is running,
Further, the tape is prevented from being loosened too much and is not caught in the mechanism, so that the tape can be prevented from being damaged.

[Brief description of drawings]

1 and 2 show an embodiment of the present invention.
FIG. 1 is an enlarged view of the main part, FIG. 2 is a graph showing the relationship between the braking force and changes in temperature, and FIGS. 3 and 4 show the state of the conventional VCR tape cassette mounting portion during braking. FIG. 5 is a plan view and a plan view showing a state at the time of releasing the braking, FIG. 5 is an enlarged view of a main part of FIG. 3, and FIG. 6 is a graph showing a relationship between a conventional braking force and a change in temperature. 16 …… Projection, 17 …… Brake arm, 18 …… Large diameter part of reel stand, 19 …… Brake shoe.

Claims (1)

[Scope of utility model registration request] 1. A magnetic recording / reproducing apparatus in which a brake shoe provided at one end of a brake arm is brought into contact with an outer peripheral surface of a reel stand to brake the rotation of the reel stand.
A magnetic recording / reproducing apparatus in which at least one end of the brake arm is provided with a protrusion having a protrusion amount slightly smaller than the thickness of the brake shoe.