JPH039123Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field]

This invention relates to a rotating head type magnetic recording/reproducing device used in helical scan type VTRs, etc., and more specifically to a rotating drum device that has an erasing head built into the rotating drum and records and plays in both the forward and reverse directions of tape running. It's about configuration.

[Conventional technology]

Conventionally, the device shown in FIG. 6 has been known as this type of device. In FIG. 6, the reference numeral 4 designates a lower drum that obliquely winds and guides the magnetic tape, and the reference numeral 2 designates a rotary drum that is rotatable by a bearing provided on the lower drum. On the rotary drum 2, a fixed magnetic head 3 for recording and reproducing is provided facing approximately 180 degrees, and a rotary erasing head 1 (so-called flying erase head) is provided at a position perpendicular to these heads for erasing recorded tracks in advance.・Erase heads) are provided facing each other at approximately 180°. The rotating drum 2 is fixed to a rotating disk 9 that is press-fitted into a drum shaft 6. The rotating disk 9 is provided with a rotor 5 of a rotary transformer, and the lower drum 4 is provided with a stator 7 opposite thereto for transmitting recording and reproducing signals. , transmits the erase signal. Figures 7 and 8 schematically show the head locus when a magnetic tape is wound diagonally around a rotating drum device for recording, playback, and erasing, and show the drum rotation locus and tape travel. (Here, we show the edges that serve as the basis for forming the track.)
T ₁ and T ₂ are formed. The rotating erase head is placed 90 degrees ahead of this on the drum, so in the forward direction,
It is higher by a(≒TP/2), and in the opposite direction it is higher by b(≒TP/2).
2) The height must be set low.

[Problem that the invention attempts to solve]

Since the conventional rotating drum device is constructed as described above, two identical rotating erasing heads are required, one for the forward direction and one for the reverse direction, in order to erase the magnetic tape in both the forward and reverse running directions. Ta. Therefore, the number of parts and adjustment man-hours increase, resulting in higher costs.Also, the rotary transformer must also be provided with a dedicated channel, and the increased number of channels in a limited space impairs the transmission characteristics of the transformer. There were drawbacks such as a decrease in This idea was made to eliminate the above-mentioned drawbacks.The erasing head is attached to a movable element, and a rotary transformer transmits a signal to drive the movable element and an erasing signal, and a single circuit erases both forward and reverse directions. It is intended to be erasable with the head.

[Means to solve the problem]

In order to achieve the above object, this invention includes a movable element that is rotatable in the direction of the rotation axis by a piezoelectric element whose one end is fixed in a rotating drum, and a single rotating erasing head fixed on the movable element. Erasing is performed by applying a signal to control the movable element to the same channel of the rotary transformer provided opposite to the fixed drum that guides the magnetic tape and the rotating drum, and the rotary transformer used for the signal transmitted to the rotary erasing head. The rotary erasing head is configured to obtain a signal and a movable element control signal, and to erase at least one track in both forward and reverse diagonal track directions.

【Example】

An embodiment of this invention will be described below based on the drawings. 1 to 5 show an embodiment of this invention, and the same parts as the conventional structure shown in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted.
In FIGS. 1 to 5, reference numeral 11 denotes an erasing head chip, which is fixed to a movable element 24 such as a piezoceramic bimorph plate. The assembly constitutes a movable head 25, which is fixed to the rotating drum 2 at a rotation angle of approximately 90° relative to the fixed magnetic head 3. Between the movable head 25 and the rotor 5 provided with a rotary transformer, a movable element 24 is connected through a rectifier circuit 53 including a low-pass filter, as shown in FIG. 5 through a high pass filter. Reference numeral 51 denotes an erasure signal circuit connected to the stator 7 provided with a rotary transformer, which is mixed with a signal from the movable element driving circuit 52 and connected to the rotor side through the rotary transformer stator. The rotary erase head is formed, for example, with a track width approximately twice the track pitch and a 0° azimuth. The operation of the magnetic recording/reproducing apparatus configured as described above will be explained. First, the recording in the forward direction will be explained. When recording in the forward direction, an erase signal and a recording signal flow to the rotary transformer according to a preset recording/erasing head height difference (for example, approximately half the track pitch). Therefore, no signal flows through the movable element driving circuit 52, and therefore the movable element 24 will not be biased. and,
When re-recording on a used tape, the previously recorded track is erased by the rotary erasing head 11 while the locus of the same track is recorded by the rotary head 3. Next, recording in the reverse direction will be explained. At this time, the track to be recorded can be erased in advance by applying a displacement to the movable element corresponding to the difference in height of the erasing head in the forward direction and in the reverse direction (for example, approximately half the track pitch). That is, the low frequency exchange frequency f ₁ of the level corresponding to the drive voltage to the movable element for the above displacement is set to
It is generated by the movable element driving circuit 52. Then, the AC frequency f ₂ (f ₁ < f ₂ ) generated in the erasure signal circuit 51
and mixes it and supplies it to the rotary transformer.
As a result, a DC voltage for driving the movable element is generated through the rectifier circuit 53 including the above-mentioned low-pass filter, and the movable element 24 can obtain a predetermined displacement amount.
It is held at that height position. The erase signal passes through a high-pass filter in the rotary transrotor 5 and is applied to a rotating erase head 11 for erasing. In the above embodiment, the movable element is moved in the reverse direction, but it may be driven in the forward direction, or the movable element may be displaced in the forward and reverse directions. However, when displacing in both forward and reverse directions, it is necessary to use different frequencies of the erase current. Furthermore, although the rotary transformer has been described as a plate-shaped rotary transformer, it may be a coaxial rotary transformer.Furthermore, although the rotary transformer for the rotary erasing head is the same as the recording/reproducing transformer and has a channel, it may be a separate rotary transformer. Further, although the movable element is driven with a constant voltage, it may be driven with alternating current without providing a rectifier circuit as long as it does not interfere with erasing. Furthermore, although the above movable element has been described only for erasing, it can also be used for other purposes, such as during high-speed searching.

[Effect of the idea]

As explained above, according to this invention, in a magnetic recording and reproducing device that performs recording and reproducing in both forward and reverse directions, a rotating erasing head is provided in the rotating drum via a movable element, and erasing signals and erasing signals are transmitted through the same channel of the rotary transformer. Since the movable element is driven and erasing in both forward and reverse directions is performed by a single rotating erasing head, only one rotating erasing head is required.
Since it is inexpensive and can be used efficiently, and contact type power supply members such as slip rings are not used, it is possible to supply a device with a long life at low cost. It is particularly effective for forward and reverse recording and playback in multi-PCM recording and playback on 8mm VTRs.

[Brief explanation of drawings]

1a and 1b are cross-sectional views and schematic cross-sectional views in the b-b direction of a rotating drum device showing an embodiment of this invention, and FIGS. 2 and 3 are main parts of a rotating drum device according to this invention. 4 is a side view of the movable head, FIG. 5 is an electrical circuit diagram showing the connection between the rotary erasing head and the movable element in the rotary drum device according to this invention, and FIGS. 6a and 6b are views of the conventional drum. A cross-sectional view of the apparatus and a schematic cross-sectional view in the bb direction thereof, FIGS. 7 and 8 are diagrams showing the head displacement trajectories of the rotary erasing head and the rotary head when the tape running direction is in the forward direction and in the reverse direction, respectively. DESCRIPTION OF SYMBOLS 1... Rotating erase head, 2... Rotating drum, 3... Rotating head, 24... Movable element.

Claims (1)

[Scope of utility model registration request] In a rotating head type magnetic recording and reproducing device that winds a magnetic tape diagonally around a rotating drum and runs the magnetic tape in both forward and reverse directions for recording and reproducing, the rotating head is attached to the rotating drum and performs recording and reproducing, and one end is attached to the rotating head. A movable element made of a piezoelectric element fixed in the drum and movable in the direction of the rotation axis, a single rotating erasing head fixed on the movable element, a fixed drum that guides the magnetic tape, and a movable element that faces the rotating drum. A rotary transformer installed in
A signal for controlling the movable element is applied to the same channel of the rotary transformer used for the signal transmitted to the rotary erasure head to obtain an erasure signal and a movable element control signal. A rotary head type magnetic recording/reproducing apparatus characterized in that the erasing of one track or more is performed by the rotary erasing head.