JPS6235138Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to a rotating magnetic head device in a magnetic recording and reproducing device, and is a rotating magnetic head device that can correct so-called tracking error during special playback of a video tape recorder (hereinafter referred to as VTR), for example. It relates to a head device.

Generally, in a VTR, normal recording and playback is performed by running a magnetic tape wound at a predetermined slope on a rotating magnetic head device at a constant speed, so changing the tape running speed causes It becomes impossible to trace the regular recording track of the magnetic tape with the rotating head. In other words, in special playback such as so-called still (still screen) playback, slow motion playback, or quick motion playback of a VTR, the rotation of the rotating head is stopped in order to stop the tape running, reduce or increase the running speed. A deviation occurs in the positional relationship between the travel locus and the video track of the tape, resulting in so-called tracking error. In such a reproduction state, video signals of adjacent video tracks, guard band noise, etc. cause interference, and it is, of course, impossible to obtain a clear reproduced image. Conventionally, during special playback such as changing the tape speed during VTR playback, the relative positional relationship between the tape and the rotary head was adjusted mechanically, for example by shifting the position of the tape guide, or by adjusting the relative position of the tape and the rotating head mechanically, or using a device such as a bimorph. A method of adjusting the running trajectory of a rotating head using a so-called wobbling method using an electro-mechanical conversion element, and correcting the amount of displacement of the running trajectory of the rotating head with respect to a regular video track on which a video signal is recorded. was proposed.

However, the positional relationship between the traveling trajectory of the rotary head and the video track cannot be adjusted with high precision by simply performing mechanical adjustment as in this method, and the adjustment method using electromechanical transducers cannot achieve this. The disadvantages include that the control circuit and drive circuit become complicated, and that an extra sliding contact is required to detect the amount of displacement, which requires a larger structure.

The present invention was devised to solve the above-mentioned drawbacks, and the head drum equipped with the rotating head is mounted on a non-contact type bearing. An object of the present invention is to provide a rotating magnetic head device in which a current proportional to the difference from the tilt angle is passed through an electromagnetic coil, and the rotation axis of the head drum is tilted by the attraction or repulsion of the electromagnet, thereby obtaining as normal a reproduced image as possible. It is something to do.

Next, an embodiment of the present invention will be described based on the drawings. FIG. 1 shows a so-called two-head type rotating magnetic head device in which two rotating heads 3 are disposed on a head drum 2. axis 1
is supported by a magnetic bearing 5 which is a non-contact bearing.
The magnetic bearing 5 is housed in a housing 4 and is provided with an upper opening 7 and a lower opening 8 for tilting the rotating shaft 1.
A hole 9 is bored in the right side of the magnetic bearing 5 to attach an electromagnet 6 as a displacement mechanism for attracting or repelling the magnetic bearing 5. Note that a and b are input terminals for passing current through the coil of the electromagnet 6 in order to tilt the rotating shaft 1, and are connected to a power source (not shown).
Incidentally, the correlation between the video track and the traveling locus of the rotary head 3 is as follows.

That is, as shown in FIG. 2, if the running direction of the rotary head 3 is A and the running direction of the tape T is B, the video signal is recorded on an oblique track shown by a solid line, and the inclination angle is θ. During normal reproduction, the rotary head 3 travels along a track 11 indicated by a broken line at the same angle of inclination θ.

However, during special playback, such as still playback or slow motion playback, the tape stops running or slows down, so the rotating head moves over the track at an inclination angle greater than the angle θ, as shown by the broken line in Figure 3. 3 runs. On the other hand, in the case of quick motion playback such as double speed playback, the running speed of the tape is high, so the rotary head runs at an angle of inclination smaller than the angle θ, as shown by the broken line in FIG.

By the way, in this embodiment in which the rotating shaft 1 of the head drum 2 is supported by the magnetic bearing 5 as described above, the rotating shaft 1 is supported by the attractive force or repulsive force of the electromagnet 6 as shown in FIGS. 6A and 6B. The above magnetic bearing 5
This angle can be changed by adjusting the magnitude and direction of the current flowing through the electromagnet 5.
When the rotary shaft 1 is tilted, since the rotary head 3 is disposed on the head drum 2, its traveling trajectory becomes a gentle wavy trajectory as shown by the broken line in FIG. 5, and it should approximately match the regular video track. I can do it. In the embodiment described above, by keeping the amplitude of the wave within two video track widths, it is possible to prevent tracking errors from affecting the quality of the reproduced image.

Therefore, the magnitude of the inclination angle of the travel locus of the rotary head 3 during special playback is correlated in advance with the angle to be corrected of the rotary shaft 1, and the correspondence between the correction angle and the current to be passed through the electromagnet 6 is established. If this is done correctly, any type of reproduction can be handled.

As is clear from the description of the above embodiments, the rotating magnetic head device according to the present invention includes a head drum on which a rotating head is disposed, a magnetic bearing that supports the rotating shaft of the head drum, and It is characterized by comprising an electromagnet that attracts or repulses the rotating shaft magnetic bearing portion to tilt the rotating shaft at a predetermined angle and selectively displaces the traveling locus of the rotating head. The running trajectory of the rotary head can be easily corrected according to the tape running speed, any special playback can be handled appropriately, and high-quality VTR playback images can always be obtained.

[Brief explanation of drawings]

Fig. 1 is a longitudinal sectional view of an embodiment of the rotating magnetic head device according to the present invention, Fig. 2 is a diagram of the relationship between a normal video track and the traveling locus of the rotating head, and Fig. 3 is a diagram for still playback or slow motion playback. FIG. 4 is the relationship diagram for quick motion reproduction, FIG. 5 is the relationship diagram when the device of the present invention is installed, and FIG. 6 is when the displacement mechanism is applied to the rotating shaft. It is an enlarged view of the main part. 1... Rotating shaft, 2... Head drum, 3... Rotating head, 4... Housing, 5... Magnetic bearing,
6...Electromagnet.

Claims (1)

[Scope of utility model registration request] A head drum on which a rotating head is disposed, a magnetic bearing that supports the rotating shaft of the head drum, and the rotating shaft is tilted at a predetermined angle by attracting or repelling the rotating shaft magnetic bearing depending on the tape running speed. and an electromagnet for selectively displacing the travel locus of the rotary head.