JPH0127175Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a moving mechanism for a magnetic head in a magnetic drum device that records and reproduces analog/digital signals using a multi-track method. This invention relates to a magnetic head moving mechanism that allows the magnetic head to accurately select a track even if there is a run-out of the lead screw.

BACKGROUND ART Announcement systems using magnetic drum devices are known for automobile OK monitors, vending machines, various terminal devices, elevators, various public notice devices, and the like. In these applications, there are requirements such as being able to directly record and play back audio information, and being able to randomly access a large amount of audio information. This is because the above requirements can be met by recording and reproducing information on each track via the track.

Access of the magnetic head to the track of the magnetic drum is achieved by a magnetic head moving mechanism provided in the vicinity of the magnetic drum. Conventional magnetic head moving mechanisms have a structure in which rotational motion of the lead screw is converted into reciprocating motion of the nut by a combination of a lead screw and a nut that is threaded onto the lead screw. That is, a guide rod is provided near the magnetic drum and parallel to its rotation axis, a carriage member is mounted with a magnetic head and into which the guide rod is slidably inserted, and a carriage member is provided that rotates parallel to the guide rod. The structure includes a lead screw that is freely disposed and engages with a nut portion formed on the carriage member, and the carriage member is moved by rotation of the lead screw by a track selection motor.

However, in such a magnetic head movement mechanism using a threaded connection between the lead screw and the nut, a certain amount of clearance is essential between the lead screw and the nut, and as a result, backlash naturally occurs. This is the positional deviation of the magnetic head (track deviation during track selection).
It was the cause of Furthermore, if the lead screw has a center runout that exceeds the clearance, the carriage members may become difficult to move, or even stop moving.Therefore, it is unavoidable that a considerably large clearance must be provided, and the position of the magnetic head The discrepancy was quite large.

As an improved version of this, as seen in Japanese Utility Model Application Publication No. 57-8687, a carriage member having a structure in which the clearance is increased and a part of the nut portion is notched is used, and the lead screw is thereby rotated. Some proposals have been made to reduce the frictional resistance during movement and at the same time absorb differences in thermal expansion due to temperature changes, thereby expanding the operating temperature range and allowing smooth movement of the carriage member. However, even with these improvements, since the movement is basically transmitted through the threading of the lead screw and the nut, the problem of the magnetic head positioning shifting due to backlashing cannot be solved, and a large clearance is required. There still remained the drawback that if the lead screw center runout exceeded the clearance that could be removed, the carriage member would become difficult to move. Furthermore, if the carriage is extended to both ends due to an abnormality in track selection, it will tighten, making automatic return difficult.

The purpose of the present invention is to eliminate such drawbacks of the conventional technology, and to enable smooth movement of the carriage member even if a considerable amount of core runout occurs in the lead screw, without buckling or backlash, and therefore always Accurate track selection operation can be performed, and even if the needle reaches both ends due to abnormal track selection, the needle will escape when a certain amount of force is applied, preventing the needle and lead screw from tightening and allowing automatic return. The object of the present invention is to provide a mechanism for moving a magnetic head.

The present invention, which can achieve the above objects, replaces the nut part in the prior art with:
It uses a needle that is pressed by a spring, and includes a needle arm that is rotatably mounted on the carriage member in a plane perpendicular to the lead screw axis, and a lead that is attached to the needle arm. a needle that can come into contact with the screw; a needle holding spring that is connected between the needle arm and the carriage member and applies rotational force to the needle arm; and a needle guide that restricts movement of the needle in the axial direction of the lead screw. a magnetic head moving mechanism configured to press the needle against the lead screw by the elastic force of the needle holding spring and convert rotational movement of the lead screw into movement of a carriage member via the needle; It is.

Hereinafter, the present invention will be explained in more detail based on the drawings. An embodiment of the present invention is shown in FIGS. 1 and 2. The magnetic head moving mechanism includes two guide rods 1a and 1b arranged near the magnetic drum so as to extend in a direction parallel to the rotation axis thereof, and guide cylinders 2a and 2b attached to the guide rods 1a and 1b. The carriage member 4, which is loosely fitted so that it can slide only in the longitudinal direction of the guide rods 1a, 1b without rotation, and on which the magnetic head 3 is mounted, and the guide rods 1a, 1b. The lead screw 5 is disposed in parallel with the carriage member 4 and engages with the carriage member 4 to move the carriage member 4. The lead screw 5 is positioned so as to fit into a large through hole 6 formed in the center of the carriage member 4, and is rotatably supported.
Alternatively, it is coupled to the stepper motor 7 via a transmission mechanism such as a gear. A needle arm 8 is mounted on the carriage member 4 so as to be rotatable in a plane perpendicular to the lead screw axis.
a needle 9 attached to the needle arm 8 and capable of contacting the lead screw 5; and a needle holding spring 10 connected between the needle arm 8 and the carriage member 4 to apply rotational force to the needle arm 8. and a needle guide 11 that restricts movement of the needle 9 in the lead screw axial direction. Needle arm 8
has a roughly L-shaped structure, and at its bending point,
As can be seen from FIG. 3, the carriage member 4 is mounted so as to be easily rotated by the pin 13 while being slightly raised above the upper surface of the carriage member 4 by the washer 12 or the like.
The needle 9 fixed to the tip of the short rod side of the needle arm 8 in the same direction as the long rod is a hard pin that is extremely difficult to deform.For example, a hardened stainless steel pin is suitable. The diameter is preferably such that it has sufficient mechanical strength and just fits into the trough of the lead screw 5. Such a needle 9 fits into a guide groove 14 provided in the needle guide 11, thereby being able to contact the lead screw 5 while restricting displacement of the lead screw 5 in the axial direction. ing. A tensile force is constantly applied to the coil spring 10 for holding the needle,
The tensile force presses the needle 9 against the lead screw 5. Therefore, when the lead screw 5 rotates, the rotation is converted into a movement of the needle 9 in the axial direction of the lead screw. 11, the force applied to the needle 9 causes the carriage member 4 to
The whole thing will move.

The support structure for the magnetic head 3 in the carriage member 4 is not particularly limited, and may be of any structure, but the most preferred structure is as shown in the drawings. That is, a head arm 20 is rotatably attached to the carriage member 4 at its base end, a leaf spring 21 has one end fixed to the distal end of the head arm 20, and a head holder 22 is attached to the other end of the leaf spring 21. The magnetic head 3 fixed via the magnetic head 3 and the head arm 20
The magnetic head 3 supported by the leaf spring 21 slides against the outer peripheral surface of the opposing magnetic drum 30 by the elastic force of the coil spring 23. This is the configuration.

The operation of the magnetic head moving mechanism constructed in this manner will be summarized as follows.
Needle 9 attached to needle arm 8
is pressed against the lead screw 5 by the tensile force of the needle presser spring 10. Since the needle 9 is fitted into the guide groove 14 of the needle guide 11, the needle 9 and the carriage member 4
The distance from the upper surface is always kept constant, and play between the needle arm 8 and the carriage member 4 can be absorbed.
When the lead screw 5 is rotationally driven by the stepper motor 7, a force is applied in the axial direction of the lead screw to the needle 9 which is pressed against the trough, and the carriage member 4 moves accordingly. Track selection operation of the magnetic head 3 becomes possible.

With this configuration, the lead screw 5
Even if the needle 9 runs out, it can move because it escapes along the lead screw 5 because it is pressed by the needle holding spring 10, so there is no risk of it becoming inoperable. . Furthermore, as mentioned above, since the needle 9 is pressed against the lead screw 5 by the spring 10,
There is no clearance, so the track deviation of the magnetic head does not occur, and the use of the needle guide 11 absorbs looseness in the needle arm rotation shaft, and even if the carriage is placed at both ends, the needle escapes, so the carriage and needle are tightened together. It will never become inoperable.

Furthermore, if the above-mentioned magnetic head support mechanism is adopted, even if the magnetic drum is eccentric, the resiliency of the coil spring for holding the head will
The magnetic head is always pressed against the magnetic drum surface with a substantially constant force, and the action of the leaf spring allows it to accurately contact the magnetic drum surface at the head gap position even during the head track selection operation, which is preferable. However, a configuration may also be adopted in which the magnetic head is pressed against the magnetic drum simply by a leaf spring.

Since the present invention is a magnetic head moving mechanism configured as described above, there is no possibility that the lead screw will become inoperable even if the lead screw runs out, or even if the lead screw is stuck at both ends due to abnormal track selection. It has practical effects in that it allows for smooth movement of the carriage member without bumping or rattling, and therefore allows accurate track selection at all times, resulting in a significant improvement in reliability. is extremely large.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the present invention;
The figure is a plan view thereof, and FIG. 3 is a view taken along the - arrow. 1a, 1b...Guide rod, 3...Magnetic head,
4... Carriage member, 5... Lead screw, 8... Needle arm, 9... Needle, 1
0...Coil spring for needle holder, 11...
...Needle guide.

Claims (1)

[Scope of utility model registration request] A guide rod provided near the magnetic drum and parallel to its rotation axis; a carriage member carrying a magnetic head and into which the guide rod is slidably fitted; and a carriage member that is rotatable parallel to the guide rod. A magnetic head moving mechanism comprising a lead screw disposed and engaged with the carriage member, in which the carriage member is moved by rotation of the lead screw by a track selection motor; a needle arm mounted rotatably in a plane perpendicular to the lead screw axis; a needle mounted on the needle arm and capable of contacting the lead screw; and a needle between the needle arm and the carriage member. It is equipped with a needle holding spring that is connected to apply rotational force to the needle arm, and a needle guide that restricts the movement of the needle in the lead screw axial direction, and the needle is moved to the lead screw by the elastic force of the needle holding spring. A moving mechanism for a magnetic head, characterized in that it is in pressure contact with a lead screw and converts rotational movement of a lead screw into movement of a carriage member via a needle.