JPH03292609A - Drum unit - Google Patents

Abstract

PURPOSE:To assure a prescribed head step by providing a correcting means for matching the relative height (step) of two pieces of magnetic heads after the assembly of a device for dynamic tracking with a prescribed set value. CONSTITUTION:A shim 47 which is so selected that the head step between the two magnetic heads 1 attains the prescribed set value is interposed between a mounting surface 44 of the device 21 for dynamic tracking and a mounting surface 48 of a rotary drum 4 at the time of mounting the device 21 for dynamic tracking mounted with two pieces of the magnetic heads to the rotary drum 4. The device side mounting surface 44 or the rotary drum side mounting surface 48 is so corrected and worked that the step of the magnetic heads 12 attains the prescribed set value. The drum unit having the magnetic head mounting positions of a high yield and high accuracy is obtd. in this way by adding the simple process.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a drum unit equipped with a dynamic tracking device having, for example, two heads.
In particular, it relates to adjusting the mutual heights (steps) of heads.

[Conventional technology]

First, to explain the first conventional device, FIGS. 12 to 16 show a magnetic head device disclosed in, for example, Japanese Unexamined Patent Publication No. 60-209913. In figure 0, (1) is a magnetic head, (2) is a head mounting plate to which each magnetic head (1) is attached, and ( 2a) is the reference surface of the head mounting plate (2), (
2b) is a screw (19) for attaching to the rotating drum (4).
), and (3) is an adhesive for attaching each magnetic head (1) to the head mounting plate (2). Head mounting plate (
2) is attached to the rotating drum (4),
The outer periphery of the rotating drum (4) is exposed through a window (5) provided in the rotating drum (4), and each magnetic head (1) is inserted into the magnetic tape (6) wound around the outer periphery of the rotating drum (4). ) is supported so as to make sliding contact with it. Also, (7) is a tape guide, (9) is an air groove provided in the rotating drum (4), (10) is a lead surface that guides the lower end of the magnetic tape (6), and (11) is a lead surface (10). (12) is a fixed drum that has been machined, (12) is a screw (13) for adjusting the height of the magnetic head (1), is a flange to which a rotating drum (4) is attached, and (14) is attached integrally with the flange (13). The rotating shaft (15) is a bearing that rotatably supports the rotating shaft (14) with respect to the fixed drum (11).
6a) and (16b) are the stator and rotor of the motor that rotationally drives the rotating shaft (14), (17) is the chassis to which the fixed drum (11) is attached, (18) is the drum unit, and (19) is the head mounting plate (2). ) rotating drum (
The screws (20a) and (20b) attached to 4) indicate the upper and lower parts of the rotary transformer that transmits and receives signals.

In the conventional device configured as described above, the head mounting plate (2) is made of an alloy such as brass, has a highly accurate flat reference surface (2a) on the top surface, and has a mounting screw in the center. An insertion hole (2b) to be inserted is formed,
When this head mounting plate (2) is attached to the rotating drum (4), it is positioned with high precision with respect to the rotating drum (4) using the reference surface (2a) and screwed. Further, each magnetic head (1) is adhesively fixed to the tip of the reference surface (2a) of the head mounting plate (2) via an adhesive (3), and each magnetic head (1) is fixed to the tip of the reference surface (2a) of the head mounting plate (2). (
2), the adhesive (3) is in an uncured state immediately after being applied to the reference surface (2a);
Within the thickness range of 3), the mounting condition is finely adjusted, and the predetermined head step (Z,) and gap distance (L) are adjusted respectively.
.

), after being installed with appropriate protrusion amount, head height and inclination angle, the adhesive (3) hardens.
Fixed in proper mounting condition. As the adhesive (3), for example, an epoxy resin adhesive having a low rate of dimensional change over time and a low coefficient of thermal expansion is used.

The first perspective view is a perspective view of a normal single-head mounted head base.
Although shown in FIG. 5, FIG. 16 is a cross-sectional view of the state in which it is attached to the drum unit (18), including the case where multiple heads are mounted (FIG. 12). The head mounting plate (2) to which the magnetic head (1) is attached is attached to the rotating drum (4) with screws (19), and the head height can be adjusted by pushing and pulling the screw (12) provided on the rotating drum (4). It is configured to do so.

Next, to explain the second conventional device, FIGS. 17 to 19 show a dynamic tracking device and a drum unit shown in Japanese Patent Laid-Open Publication No. 173217/1983, etc. In the figure, (21) is a dynamic tracking device. (22) is a drive coil, and (23) is a cylindrical magnet that holds the pole piece (32).

(24) is made of soft magnetic material, including an upper part (24a), a body part (
It is a dish-shaped or cylindrical yoke divided into a lower part (24b) and a lower part (24C), and a cylindrical magnetic gap (25) is formed between it and the magnet (23). (246) and (24
e) are mounting parts for mounting gimbal springs (29) and (27), respectively. The gimbal springs (29) and (27) are made of metal, for example, a copper alloy such as titanium or phosphor bronze, and have their respective circular outer circumferential portions attached in parallel to each other at attachment portions (24d) and (24e), and further include: The yoke (24) is fixed perpendicularly to the center axis B of the yoke (24) by a bobbin (34) held coaxially with the magnetic gap (25) and an adhesive (33). In addition, the magnetic head (1) is attached to the tip of the gimbal spring (29) using an adhesive (
(not shown). (31) is the mounting screw hole for fixing to the rotating drum, (35) is the yoke (24)
The first is a magnetic shielding member that prevents leakage of magnetic flux from the
Figures 8 (a) and (b) show plan views of the gimbal springs (29) and (27) shown in Figure 17, respectively. (37) is a circular outer periphery, (38) is a hole provided in the center for attaching the bobbin (34), and (39) is an arcuate notch.

Figure 19 shows the state in which this dynamic tracking device (21) is attached to the rotating drum (4). There is. (
40) is a wiring board, (41) is a screw for attaching the rotating drum (4) to the flange (13), and (20c) is a signal line from the rotary transformer (20b).

[Problem to be Solved by the Invention J] Since the first conventional device is configured as described above, the distance between the gaps between two adjacent magnetic heads (1), the amount of protrusion of the heads, and the amount of step (between the heads) relative height of 2.),
Among the relative azimuth angles, it is relatively easy to obtain accuracy for the gap distance (L,) and the head protrusion amount, but the head step amount (2,) may depend on the thickness of the adhesive (3). There is a limit to the accuracy of the adhesive jig, and the adhesive (
3) There are limits to achieving accuracy by itself,
The problem was that it was difficult to achieve accuracy. Further, it is clear that even if the head positioning technique of the first conventional device is applied to the second conventional device, the above-mentioned accuracy cannot be improved.

This invention was made to solve the above-mentioned problems, and has two magnetic heads positioned at predetermined positions with high precision at the tip of a gimbal type spring.
The object of the present invention is to obtain a drum unit that can ensure a predetermined head level difference when a dynamic tracking device is attached to a rotating drum, especially when it is difficult to ensure accuracy of the head level difference.

[Means for Solving the Problems] The drum unit according to the present invention is provided by interposing a shim between the dynamic tracking device and the rotating drum so that a predetermined head level difference is achieved when the dynamic tracking device is attached to the rotating drum, or by interposing a shim between the dynamic tracking device and the rotating drum so that a predetermined head level difference is achieved. Either the mounting surface of the dynamic tracking device is finished so as to have a predetermined head height difference, or the mounting surface on the rotating drum side is finished so as to have a predetermined head height difference.

[Effect]

In this invention, the head level difference between two heads is measured, and a selection shim is interposed between the dynamic tracking device, the rotating drum side mounting surface, and the rotating drum mounting surface so that a predetermined head level difference is achieved. The correction results in a predetermined head level difference (head mutual height).

[Embodiment J] An embodiment of the present invention will be described below with reference to FIGS. 1 to 7. In each figure (42) is a rotating drum (42) for housing the dynamic tracking device (21).
(43) is the gap of the magnetic head (1), (44) is the mounting surface of the dynamic tracking device (21) on the rotating drum (4), ) is affixed to the gimbal spring (29) and the head mounting reference surface (28) with good parallelism. (45) is an opening provided in the yoke (24) for the tip of the gimbal spring (29) to which the magnetic head (1) is attached, and (46) is the opening for rotating the dynamic tracking device N (21). This is the direction in which it is attached to the drum (4). (47) has two magnetic heads (
1) The mutual head step between the drum unit (18) (
D is a shim according to the present invention that is interposed between the mounting surface (44) of the dynamic tracking device (21) and the rotating drum side mounting surface (48) so that the predetermined setting value is reached upon completion. (3) is an adhesive for fixing the magnetic head (1) to the head mounting reference surface (28). The drum unit (18) of the present invention constitutes a VTR for dynamic tracking using a segment recording method.

Next, to explain in detail based on each figure, FIG. 1 shows a state in which a dynamic tracking device (21) equipped with two magnetic heads is attached to a rotating drum (4),
A shim (47) selected so that the head height difference between the two magnetic heads (1) becomes a predetermined setting value is attached to the mounting surface (44) of the dynamic tracking device (21) and the rotating drum (
4) and the mounting surface (48). Figure 2 is a perspective view of two dynamic tracking devices (21) attached to the rotating drum (4), and Figure 3 is a drum unit (21) equipped with the dynamic tracking device (21).
18), Fig. 4 is a view from the mounting direction of the dynamic tracking device (21), and Fig. 5 shows the two magnetic heads (1) attached to the gimbal spring (29). 6 shows the view from the direction of arrow C shown in FIG. 5. In FIG. 6, H This indicates the height to which the adhesive ( 3), from above the head mounting reference surface (28), which is the magnetic head adhesion reference surface,
The height Hl from the predetermined position of the head gap (43) is the thickness Ham of the adhesive, the height Hal, and the gap reference height H from the lower end of the head gap (43) to the predetermined position of the head gap (43). , 4. The gap reference height Ha4 is normally set to half the track width recorded on the magnetic tape. Similarly, the right magnetic head (1) is bonded with an adhesive (3). However, it is bonded so that it is spaced apart from the left magnetic head (1) by a predetermined gap distance (L,) and has a predetermined head level difference (Z). Now, the predetermined head height difference (Z), which depends on the gap distance (Ll), tape speed, drum rotation speed, etc., is determined by the head mounting reference plane (2
8) can be shown as the following equation.

z = H-x-H-1 (a) Then, the thicknesses of the left adhesive (3) and the right adhesive (3) are H,,, Has, respectively, so Z '' (L
++Ls +Hb4) (H11++H,! +H1
14)” (L+)fa+) 10 (Hbs-
H, s) + (Hba-Haa) (b), and the gap reference height difference is Ha4 = Hha, so Z = (Hb+-H-+) + CHbs
H,s) (c), where the left and right adhesive (3
), each thickness H,.

and Hbs and helad gap lower end height Hat and H
By managing Thl, equation (c) can reduce the error (Δz
1) Keep it to yourself. By the way, referring to Figure 7,
Head level difference error amount (Δ
Z, ), and a head level difference error amount (ΔZ3) based on the rotation axis, which is caused by a deviation in perpendicularity to the rotation direction between the mounting surface (48) of the rotation drum (4) and the rotation shaft (not shown). Therefore, the total head height difference error is calculated using the following formula: % Formula % () Therefore, as shown in Fig. 1, the head height difference between the two magnetic heads with respect to the mounting surface (44) of the dynamic tracking device (21) is measured, and the head height difference is calculated using the following formula: (d) Total error (ΔZ
) is selected and interposed between the mounting surface (44) and the mounting surface (48) on the rotating drum (4) side.

In this embodiment, two magnetic heads (1) are used.
Since the mounting distance (Lm) of the dynamic tracking device (21) to the rotating drum (4) is set to be sufficiently large compared to the gap distance (L,) of the left and right magnetic heads (1) during assembly, The head height difference can be corrected by inserting a shim (47) to a predetermined setting value, and since Lx/L is sufficiently large, the magnetic head gap/
There is almost no effect on the azimuth angle and the mounting posture of the magnetic head.

Next, another embodiment of this invention will be shown.

FIG. 8 shows a magnetic head (
Another method of correcting the head level difference in 1) is shown, and FIG. 9 is an explanation thereof. In FIG. The head height difference δ was measured, and the mounting surface (44) of the device (21) was finished and made into a new mounting correction surface (49) at the inclination angle (α) so that it became a predetermined set value (L, ). The inclination angle (a) is approximately given by the following equation.

L　r　　　　　　　L　I α is determined by measuring δ.

In Figure 10, the head step difference δ of the magnetic head (1) is measured using the mounting surface (44) of the dynamic tracking device (21) as a reference, and the mounting surface (44b) on one side is approximately Processing was performed to generate a new attachment correction surface (49).

Δh=L, Xtan a By measuring δ, Δh can be found.

FIG. 11 shows an example in which the mounting correction amount (Δh) is obtained by a similar method and the mounting surface (48°) on the rotating drum (4) side is corrected (53).

Further, in the above embodiment, an electromagnetic drive type dynamic tracking device has been described, but a bimorph type device may also be used, and the same effects as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, when a dynamic tracking device is attached to a rotating drum, correction processing is performed on the device-side mounting surface or the rotating drum-side mounting surface so that the step of the magnetic head becomes a predetermined set value. Alternatively, by interposing a selected shim, it is possible to obtain a drum unit with a high yield and a highly accurate magnetic head mounting position by adding a simple process.

[Brief explanation of the drawing]

1 to 7 show a drum unit according to an embodiment of the present invention, FIG. 1 is an exploded view showing a state in which a dynamic tracking device is attached to a rotating drum, and FIG.
The figure is a perspective view of the dynamic tracking device attached to the rotating drum after assembly is completed, Figure 3 is a sectional view of the main parts of the drum unit, and Figure 4 is a part of the drum unit seen from the direction in which the dynamic tracking device is installed. 5 is a plan view showing a gimbaled spring for dynamic tracking on which two magnetic heads are mounted; FIG. 6 is a detailed view showing the gap portion of the magnetic head seen from direction C in FIG. FIG. 7 is a developed view illustrating the head level difference error with respect to the drum unit rotating shaft during assembly. FIG. 8 is a front view showing another embodiment, and FIG. 9 is a schematic diagram illustrating head level difference correction in FIG. 8. FIG. 10 is a front view showing another embodiment. FIG. 11 is a developed view showing another embodiment. 12 to 14 show a first conventional device;
Figure 13 is a perspective view of the magnetic head device, Figure 13 is a front view of Figure 12 seen from the head gap direction, and Figure 14 is a perspective view showing the operating state in which the rotating drum on which the magnetic head is mounted is in contact with the magnetic tape. It is a diagram. FIG. 15 is a perspective view of a magnetic head device equipped with a normal single head. FIG. 16 is a sectional view of a drum unit equipped with the magnetic head device of FIG. 15. 17 to 19 show a second conventional device;
The figure is a sectional view showing a magnetic head for dynamic tracking, FIGS. 18(a) and (b) are plan views showing details of the gimbal spring shown in FIG. 17, and FIG. 19 is a magnetic head device for dynamic tracking. FIG. 2 is a cross-sectional view of a drum unit equipped with a In the figure, (1) is a magnetic head, (4) is a rotating drum, (21) is a dynamic tracking device, and (28) is a rotating drum.
) is the mounting reference surface on which the magnetic head is mounted, (29)
is a gimbaled spring to which a magnetic head is attached (44
) shows the mounting surface of the dynamic tracking device on the rotating drum, and (48) shows the mounting surface on the rotating drum side. In addition, in the figures, the same reference numerals indicate the same or equivalent parts.

Claims (1)

[Claims] (1) In a drum unit equipped with a dynamic tracking device that allows two magnetic heads to swing together, after the assembly of the dynamic tracking device is completed, the mutual height (step) of the two magnetic heads is adjusted to a specified level. A drum unit equipped with a correction means to match the set value.