JPH0363915A - Fine adjusting device for rotary magnetic head - Google Patents

Abstract

PURPOSE:To widely obtain an amplitude in a low frequency and to improve the followup ability in a high frequency by providing a coil for low frequency large amplitude and a coil for high frequency small amplitude, combining these two fine adjusting devices and executing control in two steps. CONSTITUTION:Two driving signals are provided. Then, the signal with the low area large amplitude is transmitted to a coil 49 and the signal with the high area small amplitude is transmitted to a coil 50 respectively. At first, a coil bobbin 51 generates large drive and yokes 36 and 38 in the lower adjusting device are moved. Further, a coil bobbin 52 generates slight drive and a leaf spring 48 is driven. Then, a head 1 is widely and precisely positioned vertically. For the adjusting devices of a rotary magnetic head, out of the two adjusting devices, the outside device is driven with the large amplitude and the inside device follows up the high frequency with the small amplitude. Thus, the magnetic head can be adjusted efficiently from the low frequency to the high frequency.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fine movement device for a rotating magnetic head of a VTR or the like that swings the rotating magnetic head in the direction of the rotation axis. [Prior Art] FIG. 3 is a cross-sectional view showing a fine movement device for a conventional rotating magnetic head disclosed in, for example, Japanese Patent Application Laid-Open No. 55-117745. In the figure, (1) is a magnetic head, (2), (3) is a leaf spring, (4) is a coil bobbin, (5) is a coil wound around the coil bobbin (4), and (6) is a permanent magnet (7).
), (8), center ball sandwiched between (9), (1
0). (11) is a yoke that forms the structure of the device by combining three parts. Next, the operation will be explained. Conventionally, helical scan V
In order to trace the records recorded in TR, etc.,
A micro-motion device using an electromagnetic coil has been devised. As shown in Figure 3, these yokes (9), (10), (11)
) to form an outer peripheral structure, and a center ball (6
) by joining them with permanent magnets (7) and (8), (6) - (7) - (10) - (11) and (11)
A magnetic circuit is formed between -(6) and similarly (6)-
A magnetic circuit is formed between (8)-(9)-(11) and (11)-(6). The coil bobbin (4) around which the coil (5) is wound is supported at its end face by two leaf springs (3), (2).
are fixed by yokes (10) and (11), respectively, and by (9) and (11), respectively. Coil bobbin (
4,) can be moved up and down in the gap between the yoke (11) and the center ball (6). The leaf spring (2) protrudes in one direction through the notch (12), and the magnetic head (1) is fixed on its upper surface. By applying return current to the coil (5), a Lorentz force is generated in the coil bobbin (4), causing the coil bobbin (4) to move, and the magnetic head (1) on the end surface of the leaf spring (2) to move slightly up and down. The amount of this fine movement is controlled by the direction and amount of current. [Problem to be solved by the invention 1 Since the conventional fine movement device of a rotating magnetic head is configured as described above, if the structure allows for a large fine vibration amplitude, the followability of high frequencies will deteriorate; There was a problem in that increasing the followability made it impossible to obtain a large amplitude. This invention was made to solve the above-mentioned problems, and the object is to obtain a fine movement device for a rotating magnetic head that has a large amplitude at low frequencies and has good followability at high frequencies. . [Means for Solving the Problems] A fine movement device for a rotating magnetic head according to the present invention is provided with a coil for low frequency, large amplitude and a coil for high frequency, small amplitude, instead of the conventional device driven by one coil. By combining these two fine movement devices and performing two-stage control, it is possible to achieve good followability from low frequencies to high frequencies. [Operation J] The fine movement device for a rotating magnetic head in this invention is efficient from low to high frequencies by driving the outer one with a large amplitude among the two fine movement devices, and the inner one tracking up to high frequencies with a small amplitude. Fine movement of the magnetic head is performed. [Embodiment] An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, (35) is a large-diameter yoke, and (40), which forms the external structure of the fine movement device of the present invention, is a permanent magnet, which is connected to (35)-(4) through a large-diameter center ball (43).
0)-(43) and (43)-(35), (51) is a large-diameter coil bobbin around which a large-diameter coil (49) is wound, and a large-diameter coil spring (4) at the end.
5) and (46) and is fixed to the large diameter yoke (35). Small diameter yokes (36), (37), and (38) are fixed to the lower end of the large diameter coil bobbin (51). Permanent magnets (41), (42) and a small-diameter center ball (44) are fixed inside the small-diameter yokes (36), (37), and (38).
) -(37)- and (37)-(44) magnetic circuit and (44) -(42) -(38) -(37) and (
37)-(44) constitute a magnetic circuit. (52
) is a light-weight small-diameter coil bobbin wound with a small-diameter coil (50), and the ends are attached with small-diameter coil springs (47) and (4).
8) supported by small diameter yokes (36), (37),
(38) is fixed. Coil spring at the bottom end (48)
The magnetic head (1
) In FIG. 2, the fine movement device (26) of the rotating magnetic head shown in FIG. 1 is fixed to the rotating drum (15) with screws (27). The head (1) on the drive unit (16) is fixed to protrude several tens of microns from the cutout window of the rotating drum (15), and the magnetic head (1) is attached to the magnetic tape (23) wound around the rotating drum assembly. In order to rotate while sliding, the rotating shaft (13) is supported by the fixed drum (28) via a bearing (14),
A pedestal (19) is fixed to the upper part of the rotating shaft (13), and a rotating drum (15) is further fixed. magnetic head (
1) The signal is transmitted through the rotatable upper transformer (17) and lower transformer (18) to the fixed drum (28) side via the connection part (20), and the coil of the fine movement device is transmitted through the connection part (22). A rotatable contactor (24) and an electrode (
25) Provide a circuit that leads to. Next, the operation will be explained. In Figure 2, tape (
23) is spirally wound around the rotating drum (15) and fixed drum (28), and when the magnetic head (1) slides around it, the reproduction signal is transferred from the tape (23) to the head (1). Recording signals are received and received from the helad (1) to the tape (23). The signal is an upper and lower transformer (17)
, (18) to the fixed drum (28) side. A drive signal for the head (1) is transmitted from the contactor (24) to the rotating electrode (25), and drives the fine movement device (26) via the connection part (22). In FIG. 1, the drive signal consists of two signals: a low-frequency, large-amplitude signal is transmitted to the coil (49), and a high-frequency, small-amplitude signal is transmitted to the coil (50). First, the coil bobbin (51) causes a large drive and the yokes (36), (37), (3) of the lower fine movement device
8), and then move the coil bobbin (52) for even finer driving.
) is raised and drives the leaf spring (48), thereby positioning the head (1) largely and precisely in the vertical direction. In the driving section, a coil bobbin is driven up and down in a magnetic field between a permanent magnet and a core by causing a current to flow through the coil. Generally speaking, increasing the playback speed of a VTR requires increasing the drive amplitude of the fine movement device, but in order to achieve this the coil bobbin becomes thicker and has a larger mass, but conversely, the followability at high frequencies becomes worse. Getting worse. However, if the coil bobbin is arranged in two stages as described above, a fine movement device for a rotating magnetic head that satisfies both specifications can be obtained. [Effects of the Invention] As described above, according to the present invention, since the drive section of the fine movement device is made into two stages, it is possible to obtain a fine movement device for a rotating magnetic head with large amplitude and good high frequency characteristics, which is suitable for high-speed searches in VTRs, etc. This has the effect that a good reproduction screen with good tracking can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a fine movement device for a rotating magnetic head according to an embodiment of the present invention, FIG. 2 is a configuration diagram when the device shown in FIG. 1 is incorporated into a rotating head assembly, and FIG. FIG. 3 is a cross-sectional view showing a fine movement device for the head. In the figure, (1) is a magnetic head, (35) is a large diameter yoke, (36) to (38) are small diameter yokes, (49) is a large diameter coil, (50) is a small diameter coil, and (51) is a large diameter Coil bobbin (52) indicates a small diameter coil bobbin.

Claims (1)

[Claims] (1) Equipped with a coil for low frequency, large amplitude and a coil for high frequency, small amplitude, and by combining these two fine movement devices and controlling in two stages, it is possible to achieve good followability from low frequency to high frequency. A fine movement device for a rotating magnetic head characterized by: