JPH026502Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a magnetic recording/reproducing device such as a VTR. In general, in a VTR, a tape end sensor is placed at a position facing the tape on the supply and take-up side to automatically stop the tape when the tape reaches the beginning and end while the tape is running. Edge detection is performed,
One method for this is to arrange metal foil such as aluminum foil at the beginning and end of the tape and detect changes in electrical conductivity with a sensor coil. In this method,
The sensor coil is constantly oscillating, and if the tape end sensor is placed close to the guide cylinder while the tape is loaded, there is a risk that it will have a magnetic effect on the built-in video head. The present invention was developed in view of the above points, and is designed so that a shield plate is arranged on the tape mounting means, and this shield plate is located between the tape end sensor and the guide cylinder when the tape is mounted. However, the present invention proposes a magnetic recording/reproducing device that can prevent magnetic influence on the video head due to oscillation of the sensor coil. An embodiment of the present invention will be described below with reference to the drawings. Figure 1 is an exploded perspective view of the main parts of the device of this embodiment;
The figure is a partial perspective view of the loading disk, and FIGS. 3 to 5 are plan views in the unloading state, fast forwarding, rewinding state, and loading state, respectively. In the figure, 1 is a guide cylinder fixed on the chassis 2 and has a built-in rotating video head, and 3 is a tape 4.
is a loading disk which is pulled out from inside the cassette 5 and wrapped around the guide cylinder at a predetermined angle, and is rotatable by having its thin inner circumferential portion 3a held by support rollers 6, 6, 6. Furthermore,
On this loading disk 3 , there is a pinch roller support lever 8 on which the pinch roller 7 is placed, tape guides 9, 9, 9, 9, 9, and magnetism applied to the rotating video head by the oscillation of a tape end sensor on the winding side, which will be described later. Metal shield plate 1 to prevent physical damage
0 is provided as shown in FIG. Reference numeral 11 denotes a clamping plate that is provided integrally with one of the support rollers 6 , and as shown in FIG. , 6 to prevent wobbling. 12 is a capstan; 13 is a pinch roller press lever for press-fitting the pinch roller 7 to the capstan 12; the roller 13b at the tip is always pressed against the cam surface 3b on the outer periphery of the loading disk 3 under the force of a torsion spring 13a; At the loading completion position, this roller enters the notch 3c, rotates counterclockwise, and presses the pinch roller 7. 14 and 15 are supply and take-up reel stands; 16 is a full-width erasing head; 17 and 17 are winding angle defining pins that define the winding angle of the tape 4 around the guide cylinder 1; 18 is an audio erasing head;
9 is an audio and control signal recording/reproducing head. Reference numeral 20 denotes a back tension lever having a back tension pin 21 disposed at its tip. This back tension lever is fixed to a first rotating lever 22 and can rotate together with it around a support shaft 23.
One end of a brake band 24 is attached to this first rotating lever, and this brake band is wound about half a circumference around the supply reel stand 14, and the other end is fixed to the chassis 2. Furthermore, 25 is a support shaft 26
The engaging pin 25a disposed at one end is engaged in the recess 22a of the first rotating lever 22. A coil spring 27 is stretched between the first and second rotating levers, and is biased to rotate in opposite directions. Further, a roller 25b is disposed on the second rotating lever 25 , and this roller is always engaged with the cam surface 3d on the inner circumference of the loading disc 3 .
The rotation of the loading disk 3 allows the back tension lever 20 to be rotated between a non-operating position and an operating position. 28 and 29 are tape end sensors on the supply side and take-up side, which detect aluminum foil at the beginning and end of the tape.
It is possible to put the VCR into an auto-stop state.
The supply side tape end sensor 28 is placed on the fixed plate 30 together with the full width erasing head 16, and its position can be fixed, while the take-up side tape end sensor 29 is placed on the third rotating lever 30 . It can be rotated to two positions facing the tape 4 in the loading complete state shown in FIG. 4 and in the fast forward and rewind states shown in FIG. 5, respectively. Said third
The rotating lever 30 is a support shaft 3 on the fourth rotating lever 31 .
1a, and is urged to rotate counterclockwise with respect to the fourth rotating lever 31 by a torsion spring 32, and the locking piece 30a engages with the boss 31b on the fourth rotating lever 31. Rotation is restricted in this state. Reference numeral 33 denotes a support plate that rotatably supports the fourth rotary lever 31 , and a boss 31b of the fourth rotary lever 31 is inserted into a support shaft 33a on this support plate. 31c and 31d are first and second engagement arms provided on the fourth rotating lever, respectively, and when the loading disk 3 rotates counterclockwise, the engagement arms on this loading disk When the piece 3e engages with the first engagement arm and the loading disc 3 rotates clockwise, the protrusion 3f on the outer periphery of the loading disc engages with the second engagement arm, causing the third rotation. Rotate the lever 30 clockwise and counterclockwise. Also, 34
is a torsion spring stretched between the support plate 33 and the fourth rotating lever ;
1 in opposite directions centering on the point of consideration, and the fourth rotating lever 31 is rotated moderately. In addition, 33
b and 33c are stoppers that respectively restrict rotation. 35 is a slide lever that slides downward in FIG. 1 to release the cassette holder locking mechanism (not shown) during eject operation, and has a locking piece 3 at the tip.
5a is provided. Reference numeral 36 designates an ejector lever that is rotatable around a support shaft 37 and is always biased clockwise by a coil spring 38, and the hook portion 36a at one end is normally attached to the locking piece 3.
5a to lock the slide lever 35 , and only during unloading, the protruding pin 3g on the lower surface of the loading disk 3 engages with the engagement piece 36b at the other end.
is engaged to release the lock. Next, the operation of the apparatus of this embodiment will be explained with reference to FIGS. 1 to 3. First, in the unloading state , that is, the stop mode, shown in FIG. Brake band 24
is spaced apart from the supply reel stand 14. Furthermore, the pinch roller 7 is also located within the notch of the cassette 5. On the other hand, the third and fourth rotating levers 30 and 31 are at positions rotated counterclockwise, and the tape end sensor 29 on the winding side faces the tape 4. Also,
In this state, the tape 4 is located a little apart from the supply tape end sensor 28. Further, the ejector lock lever 36 is in a counterclockwise rotated position because the protruding pin 3g of the loading disc 3 is engaged with the engagement piece 36b, and the slide lever 35 is in the unlocked state. , only in this case, eject operation is possible. Next, when fast forwarding or rewinding is performed from this state, the loading disk 3 rotates slightly counterclockwise and stops as shown in FIG. At this time, the second rotating lever 25 is rotated counterclockwise as the roller 25b slides on the cam surface 3d of the loading disc 3 , and in conjunction with this, the first rotating lever 22 and the back lever are rotated counterclockwise. Since the tension lever 20 rotates clockwise, the back tension pin 21 pulls out the tape 4 from the take-up reel in the cassette 5 and stops at the operating position. By rotating the back tension lever 20 to the operating position, the brake band 24 is engaged with the supply reel stand 14, and as the tension of the tape 4 increases, the brake band 24 is loosened. Further, in this state, the tape 4 faces the supply side and take-up side tape end sensors 28 and 29, respectively. Further, as the loading disk 3 rotates, the protruding pin 3g separates from the engagement piece 36b of the ejector lock lever 36, so the ejector lock lever rotates clockwise and locks the lock portion 36a.
engages with the locking piece 35a of the slide lever 35 , inhibiting the slide lever from sliding. When the loading disc 3 is started, a large load is applied to the loading disc in order to displace the roller 25b that engages with the cam portion 3d of the loading disc 3 . Since it is biased clockwise by , it assists the rotation of the loading disc 3 at the time of startup, and the substantial load applied to the loading disc 3 is reduced. Then, when the loading disk 3 rotates to a certain extent, that is, when the ejector lever 36 separates from the protruding pin 3g, the rollers etc. begin to slide in fixed positions and the load becomes lighter. Next, if you perform the play operation from the state shown in Figure 3,
As shown in FIG . 5, the loading disk 3 further rotates counterclockwise after passing through the state shown in FIG. The lever stops at the position where it enters the notch 3c of No. 3 , and this entry causes the lever to rotate counterclockwise, rotate the pinch roller support lever 8 clockwise, and move the pinch roller 7 to the capstan 12.
It is pressed into play mode. Due to this rotation of the loading disk, the first engagement arm 31c of the fourth rotation lever 31 is pressed by the engagement piece 3e on the loading disk 3 , and rotates clockwise against the bias of the torsion spring 34. When the torsion spring 34 moves past the consideration point, the biasing direction of the torsion spring 34 is reversed, and the biasing causes the torsion spring 34 to rotate clockwise and stop at the position where it engages with the stopper 33c. Therefore, the tape end sensor 29 on the winding side rotates approximately 90 degrees and comes to face the tape 4. Furthermore, in this state, since the shield plate 10 has rotated to a position opposite to the take-up tape end sensor 29, the sensor and the guide cylinder 1 face each other with the shield plate 10 in between, and the sensor oscillates. Magnetic influence on rotating video heads can be prevented. Then, when a stop operation is performed from the state shown in FIG. 5, the loading disk 3 rotates clockwise to perform an unloading operation. At this time, the protrusion 3f of the loading disc 3 engages with the second engagement arm 31d and is rotated counterclockwise, which is the opposite operation to that during loading, and the second engagement arm 31d is rotated to the stopper. 33b
It stops at the locked position and returns to the state shown in Fig. 3. Further, the protruding pin 3g on the lower surface of the loading disc 3 is connected to the engaging piece 3 of the ejector lever 36.
6b, the lock lever rotates counterclockwise to unlock the slide lever 35 . During the aforementioned loading and unloading, the tape 4 is fed out only from the take-up reel stand 15 side and wound up by the engagement of the brake band 24 on the supply reel stand 14 side. As described above, according to the present invention, since a shield plate is disposed between the tape end sensor and the guide cylinder when the tape is loaded, it is possible to prevent the magnetic influence on the video head due to the oscillation of the sensor coil. The effect is great.

[Brief explanation of the drawing]

The drawings all relate to one embodiment of the present invention.
2 is a partial perspective view of the loading disk, FIG. 3 is a plan view in the unloading state, FIG. 4 is a plan view in the fast forward and rewind states, and FIG. FIG. 5 is a plan view in a loading state. Explanation of main drawing numbers, 1...Guide cylinder, 3 ...
...Loading disk, 4...Tape, 10...
...Shield plate, 29...Take-up side tape end sensor.

Claims (1)

[Scope of utility model registration request] a tape end sensor that faces the tape in a tape mounted state and detects the beginning and end of the tape based on changes in electrical conductivity of the tape; and a tape mounting means for mounting the tape on the guide cylinder and unmounting the tape. , a shield plate disposed on the tape mounting means, and the shield plate is located between the tape end sensor and the guide cylinder in the tape mounting state. Device.