JPS5917001Y2 - cassette tape recorder - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a cassette tape recorder having an auto-shutoff mechanism, and is particularly aimed at preventing malfunctions of the shutoff.

In this type of cassette cheap recorder, a tape tension detection arm is pivotally mounted on the head board surface.
It is already well known that a change in tape tension (tension) occurring at the end of a running tape is detected and the operating system of a tape recorder is automatically restored based on the detection operation.

In other words, auto-shutoff is a relatively simple mechanical means and has been widely adopted, but its operation is not always reliable.For example, it may shut off due to a change in tension at the beginning of tape running, There are various factors in total, such as the same behavior due to instantaneous tension changes associated with fast-forwarding and rewinding operations including review, or failure to shut off when the tape ends in a normal state. This tends to cause functional variations.

Note that this tendency is also reflected in the auto music sensor (
This is even more noticeable on models equipped with the following).

An object of the present invention is to improve the above-mentioned problems of the auto-shutoff mechanism in a cassette tape recorder.

First, with reference to FIGS. 1 and 2, a specific example of a cassette tape recorder having an auto-shutoff mechanism and a means considered to be effective as a preventive measure against malfunction of the shut-off will be briefly described.

However, both figures are route plan views of the main parts for convenience of explanation.

In Fig. 1, 1 is a chassis that constitutes a tape recorder, 2 is the whole tape cassette mounted at a predetermined position, 3a and 3b are hubs on the feeding side and the winding side, and both hubs are connected to the respective reels. As is well known, the tape T from the hub 3a is stretched between the guide rollers 3C and 3d on both sides of the cassette, and is connected to the tape bus at the front of the cassette. run along.

Reference numeral 4 indicates a group of operation button levers arranged on the front side of the aircraft, and reference numeral 5 indicates a head board. This head board moves forward by pressing the play (forward) button lever 4a in the direction of the solid line arrow, and moves in the restoration direction of the dashed line arrow. It follows and retreats, but
The play button lever 4a, together with the other push button levers except the stop button lever, is locked in the pressed position by a lock plate 6A as shown in the figure (such a mechanism is a conventional means, and the pause button lever etc. are directly related to the lock plate). ).

Further, 7 and 8 are recording/reproducing heads and pinch rollers provided on the surface of the head substrate 5, 9 is a capstan that protrudes from the chassis 1 and rotates at a constant speed in a counterclockwise direction, and 10 is a shut integrated with this capstan. Showing off-cam.

The outline of the above auto-shutoff mechanism in this example is as follows:
A tape tension detection arm 11 is mounted on the surface of the head substrate 5.
A release lever 12 is provided at a predetermined position on the chassis 1 to be rotated in conjunction with the detection arm 11, and the release lever 12 and the lock plate 6 are linked together. However, as shown in the figure, the detection arm 11 in the example has an abbreviated shape and is attached to the vicinity of the edge of the head board 5 by a pivot pin 13, and one end thereof is inserted through a small window on the left side of the front surface of the cassette 2. It is a swinging arm that is provided with a sliding contact piece 14 that comes into contact with the surface of the tape T, and has a pressing pin 15 planted at the other end.

On the other hand, the release lever 12 is a lever that extends diagonally from the lower side of the pinch roller 8 to a position where it contacts the right end of the lock plate 6A, and its approximately central portion is fitted into a pivot 16 planted on the surface of the chassis 1. It is rotatable, and on the side of the head substrate 5 that is one end thereof, there is a protrusion 17 in contact with the pressing pin 15 of the detection arm 11 and the above-mentioned shut-off cam 10.
The other end has a retaining pin 19 for a dashpot rod, which will be described later, and one side thereof is in contact with the right end of the lock plate 6A.

Note that 20 represents a spring that applies biasing force to the release lever 12 in a counterclockwise direction.

Incidentally, the illustrated state shows the state immediately before reaching the end of the tape during play (including during recording), and is intended to explain the so-called normal shut-off operation mentioned above. As is already clear in the play state, the head board 5
As the recording/reproducing head 7 moves forward, it enters the tape path from the front central opening of the cassette 1 and comes into sliding contact with the surface of the tape T. At the same time, the pinch roller 8 also enters the opening on the right side of the cassette and passes through the tape T to the capstan 9. This makes the tape T run at a constant speed in the forward direction.

In addition, the right end pin 15 of the tension detection arm 11 on the head board is biased clockwise around the pivot pin 13 under the pressure of the protrusion 17 of the release lever 12, and as described above, the sliding piece 14 of the tension detection arm 11 is biased toward the cassette. The tape T is in sliding contact while being bent inside the small window.

Then, soon the tape layer of the feeding-side hub 3a is fed out to the end, and the sliding contact piece 14 for increasing the tension of the tape T is naturally pushed outward, which causes the detection arm 11 to move counterclockwise (broken line Since the rotation to the direction shown in the figure is transmitted to the release lever 12 via the press pin 15, the release lever 12 also rotates clockwise, and the retaining piece 1 at the tip end of the release lever 12 also rotates clockwise.
8 and the shut-off cam 10 of the capstan 9 appear.

Therefore, the release lever 12 is further rotated by the shutoff cam 10, and the other end presses the lock plate 6A in the release direction, eventually completing the shutoff operation.

Note that the rotation process of the release lever 12 is shown by broken lines.

The above operation is an automatic shutoff at the end of the tape, and since the tape tension changes steadily and gradually increases, there is generally no risk of malfunction.

However, as mentioned earlier, the tape tension that occurs at the beginning of tape running during play operations, fast forwarding or rewinding operations changes rapidly, and it is almost impossible to avoid malfunctions at such times. Close to.

Therefore, in this example, a dashpot 21 for controlling the rotational movement of the release lever 12 is provided as a means for preventing the shutoff from malfunctioning when the tape tension changes instantaneously.

That is, this dashpot 21 is a buffer device against instantaneous loads as is generally known, and in the case shown in the figure, its simplest structure is that of a fluid (air or oil).
Slide the rod 23 into the cylinder 22 filled with
The protruding end of this rod 23 is provided with a through hole into which the engaging pin 19 of the release lever 12 described above is inserted, and the release lever 12 and the dashpot 21 are connected to each other, so that the release lever 12 can be rotated when the tape tension changes instantaneously. This was done in order to suppress the occurrence of four shutoffs, and theoretically it can be considered that if such a dashpot 21 is provided, malfunctions of the shutoff can be prevented to some extent.

However, as a practical matter, when this type of dashpot is mass-produced and the setting criteria consisting of individual shock absorbing force and changes over time are considered, the first thing to consider is the degree of sliding (clearance) between the cylinder 22 and the rod 23. As a result, there are considerable variations in the buffering force of each product, and there are also changes in the operating force due to repeated use, and changes in viscosity due to the influence of outside temperature in the case of oil-filled products. In conclusion, we have come to the conclusion that there is still room for research in order to attach such dashpots to mass-produced tape recorders and to obtain a uniform buffering force for all of them.

Next, with the intention of further confirming the above points, we will briefly describe the main parts of a cassette tape recorder that is similar to the previous example and incorporates one type of auto music sensor, with reference to Figure 2. Corresponding parts are given the same reference numerals and redundant explanation will be omitted.

In the one-type auto music sensor of this example, while the recorded tape is being played back [the play button lever 4a is locked to the first lock plate 6A], the fast forward button lever or the rewind button lever 4b is locked to the second lock plate 6B. The figure shows only the locked state of the rewind button lever), a cueing system that detects the no-signal part between songs on the tape by the recording/playback head 7 and automatically starts the playback state from that part. As shown in the figure, a second lock plate 6B that locks the rewind button lever 4b is connected to a plunger 24, and this plunger 2
4 is the second
The lock plate 6B is moved in the release direction.

In the process of cueing, the head substrate 5 is naturally moved back a little, and the pinch roller 8 is also separated from the capstan 9, but at the initial point of cueing, the head substrate 5 moves forward instantly, and therefore, especially In the case of rewinding, the pinch roller 8 comes into contact with the capstan 9 before the rotational inertia of the hub 3a rotating at high speed in that direction disappears, and the tape T
Momentary tension is generated, causing the shutoff mechanism to malfunction.

In other words, this is the cause of the remarkable malfunction as mentioned earlier, and in this example, the dashpot 21 is similar to the example in FIG.
However, the reliability of this dashpot has already been revealed.

In short, the problem is that we must provide a reasonable damping means to replace the dashpot, that is, a damper that operates effectively.
The result is that malfunctions of the shutoff cannot be prevented in this type of cassette tape recorder.

The inventors of the present invention conducted many experiments in view of the above-mentioned problem, and as a result, they developed a magnetic damper as described below.

FIG. 3A is a partially cross-sectional perspective view showing an example, and the reference numeral 25 is
26 is a cylinder made of a non-magnetic material such as brass, and 27 is a slide rod made of a magnetic material that is fitted into the inner hole of the magnetic damper and has a protruding front end. )・Part 27
A through hole 28 is provided in this flat portion, and the engaging pin 19 of the above-mentioned release lever 12 (FIGS. 1 and 2) is inserted and connected thereto.

In this example, a magnet 29 made of ferrite, for example, is attached to the rear end of the cylinder 26 to attract the slide rod 27, but the shape of the magnet 29 is at the center of one side of a solid body having the same diameter as the cylinder 26. The diameter of the protrusion 29' is larger than the inner diameter of the cylinder, and the rear end of the cylinder 26 has a countersunk recess into which the protrusion 29' is fitted. It has a structure in which magnets 1 to 29 are installed after processing.

Therefore, considering the function when such a magnetic damper 25 is installed in place of the dashpot 21, the force (attractive force) of the magnet 29 against the slide rod 27 is inversely proportional to the square of the distance, and therefore, the instantaneous In the event of a significant change in tape tension (in this case the tension is relatively small), the release lever 12, which is intended to be pivoted, is completely damped.

In addition, in a normal shutoff operation at the end of the tape, if the slide rod 27 moves a little away from the magnet 29, the force of the magnet will rapidly attenuate, and it will hardly work at the position where the slide rod 27 has moved a certain distance, so the subsequent shutoff The operation is smooth, and what is particularly noteworthy is that there is no functional variation or change over time like with a dashpot.In addition, the manufacturing advantages cannot be overlooked as a major advantage.

3B, C, D, E, F, and G show other modifications of the magnetic damper 25, and in all of them, the same reference numerals are given to corresponding parts to those in FIG.

First, in the example shown in Fig. B, the outer diameter of the rear end of the cylinder 26 is a stepped small diameter part, and a ring-shaped magnet 1 is attached to this part.
At the same time, a stopper 27b is formed on the front part of the slide rod 27, and this stopper is connected to the cylinder 2.
This is a magnetic damper having a structure located within a counterbore recess on the front end surface of No. 6.

Furthermore, Fig. C is an example in which a conical recess 30 is formed in the protrusion 29' of the magnet 29B, which is substantially the same as the example shown in Fig. A, and the inner end of the slide rod 27 is fitted into this conical recess.

In the example in figure D, the front end of the cylinder 26 is made a small diameter part, and a ring-shaped magnet 29C, which is narrower than in the example in figure B, is fitted into this part.
This is a magnetic damper in which a flange 31 is formed in contact with and spaced apart from 9C, and FIG.

The magnetic damper shown in Fig. F is an example in which a small-diameter ring-shaped magnet 29E is inserted into the cylinder 26 so that the end of the slide rod 27 enters, and a lid 32 is attached to hold it.

Furthermore, in Figure G, the inner hole of the cylinder 26 with the rear end closed is expanded, and magnetic powder is mixed into the expanded hole, molded, and magnetized to form a resin magnet (29F). Although an example of fitted magnetic dampers is shown, it can be understood that the function performed by each magnetic damper 25 is substantially the same as that in the example shown in Figure A.

Thus, the effects of the present invention are already clear.
The fact that the automatic shutoff operation of the cassette tape recorder can be ensured by providing a magnetic damper in place of the dashpot is highly praised.

[Brief explanation of the drawing]

Figures 1 and 2 are plan views of the main parts of a specific example of a cassette tape recorder having an auto-shut mechanism and an example of a shut-off malfunction prevention means, and Figure 3 is a perspective view showing an example of a magnetic damper. FIG. In the figure, 2 is a tape cassette, 4a is a play button lever, 4
b is a rewind button lever, 5 is a head board, 6A and 6B are lock plates, 7 is a recording/reproducing head, 8 is a pinch roller, 9 is a capstan, 10 is a shut-off cam, 11 is a detection arm, 12 is a release lever , 21 is a dashbot, 24 is a plunger, 25 is a magnetic damper, 26 is a cylinder, 27 is a slide rod, 29, 29 A, 29 B
, 29 C, 29 D, 29 E and 29 F represent magnets, and T represents tape.

Claims (1)

[Scope of utility model registration request] A tape tension detection piece arm is disposed on a part of the head board to detect the change in tension at the end of the running tape, and one end of the release lever that is displaced in conjunction with the detection operation of the detection arm and the cuff stand are arranged. Or, in a tape recorder equipped with a shut-off mechanism in which the interlocking member and an integral cam are inserted and the other end of the release lever automatically restores the operation system, etc., the shut-off mechanism is A cassette tape recorder having a structure in which a magnetic damper is installed in the member, and malfunction of the shut-off is prevented by the action of the magnetic damper.