JPS633373B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION An object of the present invention is to provide a head drum device in which the magnetic head does not wear out during fast forwarding and rewinding of a magnetic tape.

In a head drum device that fast-forwards and rewinds the magnetic tape with the magnetic tape wound around the drum, the rotating head also comes into contact with the magnetic tape during fast-forwarding and rewinding of the magnetic tape, causing wear on the leading end of the head. In particular, when the magnetic tape is in fast-forwarding or rewinding mode, the running becomes unstable and abnormal tension is more likely to be applied than in the recording or reproducing mode, and head wear is more likely to occur.

Conventionally, as a measure against head wear during fast forwarding and rewinding of a magnetic tape, a method has been used to forcibly blow air from inside the rotating drum to create a sufficiently large air layer between the drum and the magnetic tape to prevent contact between the head and the magnetic tape. Alternatively, there is a method using a piezoelectric element to retract the head into the drum during fast forwarding and rewinding of the magnetic tape. However, the former method requires an air compressor to produce compressed air, making the equipment complicated and large, resulting in increased costs. In the latter case, there is a problem of wear or sliding noise of the high voltage generator or shield against the high voltage applied to the piezoelectric element that moves the head, and the slip ring and brush for sending the high voltage to the rotating drum. One solution to this problem of head wear is to stop the rotation of the head, but the top drum rotating type has the disadvantage that an air layer cannot be formed between the magnetic tape and the top drum surface, which increases the running load.

The present invention provides a head drum device in which there is no change in running load and in which the head is not worn out. Hereinafter, an embodiment of the present invention will be described with reference to the drawings, and an example in which the head drum device is used in a 1-head Ω-wound drum device will be described. Explain. A lower drum 2 having a lead surface 3 is fixed to the housing 1 . On the other hand, two bearings 4a and 4b provided in the center hole of the housing 1
is held on the hollow shaft 5 by. Lower drum 2 of shaft 5
A middle drum 8 with a rotary transformer 7 attached to the head 6 and the housing 1 is fixed to one side, and a stator 9 attached to the housing 1 and a magnet 1 forming a direct motor are attached to the other end.
0 and a reinforcing plate 11 are incorporated. The stator 9 and magnet 10 drive the middle drum 8. Axis 5
Two bearings 12a and 12b are attached to the hollow part of the shaft 13 to hold the shaft 13, and the shaft 13 is rotatable relative to the shaft 5. The shaft 13 is rotatable relative to the shaft 5. An upper drum 14 is attached to the lower drum 2 side of the shaft 13, and a pulley 15 is provided at the other end to transmit rotation of a motor 18 via a belt 16 and a pulley 17.

In order to match the phase of the video head 6 and the recording video signal, the middle drum 8 is equipped with a magnet 19 and the housing 1 is equipped with a Hall IC 20 to generate a PG signal.The PG signal is compared with a reference, and the middle drum 8 is moved at a constant speed. It's rotating.

On the other hand, the upper drum 14 is driven by a motor 18 and is independent of the rotation of the middle drum 8.

The housing 1 also includes a frame 24, a solenoid 26 mounted on the frame 24,
Lever 2 slidably mounted on frame 24
The roller 21 and the shaft 2 rotatably attached to the shaft 2
3 and a lever restoring spring 25, the middle drum stop positioning device is fixed. The reinforcing plate 11 has grooves 2
There are 7. The positional relationship between the groove 27 and the roller 21 is as follows:
The head 6 is set to be located on the unwound portion of the magnetic tape.

During recording or playback, the middle drum 8 rotates at a constant rotational speed, but when fast forwarding or rewinding the magnetic tape, an electromagnetic brake is first applied by the direct motors 9 and 10. At this time, the PG signal interval gradually becomes longer. When the PG signal interval exceeds a certain value, the solenoid 26 is turned on, the lever 22 is pulled up, the roller 21 comes into contact with the reinforcing plate 11, and the drum 8 stops rotating while the roller 21 enters the groove 27. At this time, the upper drum 14
continues to rotate, forming a sufficient air layer, and the running load remains unchanged. At this time, magnet 19, Hall IC 2
FIG. 2 shows a schematic diagram of the positional relationship among the head 6, the roller 21, and the groove 27. At this position, the output of the Hall IC 20 is detected and the head 6 is correctly connected.
Confirm that has escaped from the magnetic tape 30,
Fast forward and rewind the magnetic tape. In this head drum device, the entry side and exit side posts 2
8 and 29 form an Ω winding, there is a region where the head 6 does not contact the magnetic tape 30. The present invention takes advantage of this area.

According to the present invention, head wear during fast forwarding and rewinding of a magnetic tape can be prevented. At this time, since the upper drum continues to rotate, the running load on the magnetic tape does not change.

[Brief explanation of the drawing]

FIG. 1 is a sectional front view of a head drum device according to an embodiment of the present invention, and FIG. 2 is a principle diagram of a portion of the same device. DESCRIPTION OF SYMBOLS 1... Housing, 3... Lead surface, 2... Lower drum, 6... Head, 5... Shaft, 8... Middle drum, 9... Stator, 10... Magnet, 11... Reinforcement plate, 27 ... Groove, 21 ... Roller, 22 ... Lever, 26 ... Solenoid, 25 ... Spring.

Claims (1)

[Claims] 1. A lower drum fixed to the housing and having a lead surface, an intermediate drum attached to the housing by means rotatable coaxially with the lower drum and having a head attachment means, and an intermediate drum having a lead surface coaxially with the lower drum. an upper drum rotatably attached to the housing or the middle drum with respect to the housing and the middle drum; driving means for the middle drum and the top drum; and position detection of the middle drum. and a stop position holding means for the middle drum, which rotates the upper drum and holds the middle drum at a stop position when the magnetic tape is wound. A head drum device characterized in that the head drum is stopped so that the head drum is in a position where the head drum is stopped.