JPS6222223A - Rotary head device - Google Patents

Abstract

PURPOSE:To improve the turning accuracy of a rotary drum by inserting a pre-load spring giving a pre-load to the bearing in the thrust direction between the bearing fitted to a shaft fitting the rotary drum and other bearing. CONSTITUTION:The shaft 21 is fitted to a sleeve 31 fitted to the rotary drum 32. A rotor magnet 45 is fitted to a lower part of the shaft 21 via a support member 43 and a yoke 44 and the shaft 21 and the rotary drum 32 are driven by flowing a current to a stator coil 47 fitted to a base 46. The bearings 22, 24 incorporated to the shaft 21 are fitted to the upper and lower ends of the inner diameter of the stator drum 33. The bearings 22, 34 are subject to preload in the load in the thrust direction to the inner race of the bearings 22, 34 by the elastic pressure of a pre-load spring 36. Since the pre-load is almost unchanged due to temperature change, generation of radial clearance of the bearings 22, 34 is prevented.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a rotary head device installed in a magnetic recording/reproducing device such as a VTR or PCM tape recorder, and in particular improves a bearing mechanism that rotatably supports a rotating drum. The present invention relates to a rotary head device.

[Prior art]

FIG. 6 shows a conventional rotary head device in a half sectional view.

In this rotating head device, a pair of radial bearings 2 and 3 are fixed to the inner diameter portion of a fixed drum l by means such as press fitting or shrink fitting.
The shaft 4 is rotatably supported by. A sleeve 5 is fixed to the upper end of the shaft 4, and a rotating drum 6 is fixed to the sleeve 5. A magnetic head 8 is supported on the inner lower surface of the zero-rotation drum 6 via a member 7 for mounting the head. has been done. A magnet support member 9 is fixed to the lower part of the shaft 4, and a rotor magnet 11 is fixed to the magnet support member 9 via a yoke 10. Further, a stator coil 12 is fixedly installed on the lower surface of the fixed drum l. When a current is passed through the stator coil 12, the rotor magnet 11 is driven to rotate.
At the same time, the shaft 4 and the rotating drum 6 rotate. The magnetic tape is hung on the outer peripheral surfaces of the fixed drum 1 and the rotating drum 6, and the recording surface of the magnetic tape is scanned by a magnetic disk 8 provided on the rotating drum 6. Further, the read signal by the magnetic helad 8 is transmitted from the rotor transformer 13 to the stator transformer 14 and taken out to the outside.

To assemble this rotary head device, after fixing the bearings 2 and 3 to the fixed drum 1, the shaft 4 is inserted, and the preload collar 1 is attached to the shaft 4 from the bottom of the fixed drum 1.
5 and a preload ring 16 are attached, and the preload bush 17 is fixed with a set screw 18. When fixing this set screw 18, apply a preload force.

The inner ring of the radial bearing 3 is pressed upward with appropriate pressure through the roller 15 and the preload ring 16, and a preload in the thrust direction is applied to the radial bearings 2 and 3.

[Problems with conventional technology]

However, the conventional rotary head device shown in FIG. 6 has the following problems.

(1) Preload collar 15 as a means of applying preload to each bearing 2 and 3. Since the preload ring 16 and the preload bush 17 are installed, there is a disadvantage that there are more components in the lower part than the bearing 3, and the size is larger by one dimension. The span between each of the bearings 2 and 3 has an effect on the outer circumferential runout of the rotating drum 6, so it must be made long to some extent.

Therefore, when this span and the length of the mechanism below the lower bearing 3 are added, the axial length of the rotary head device naturally increases. However, recent VTRs
There is a demand for smaller and thinner products such as PCM tape recorders and PCM tape recorders. Particularly when used as a car-mounted tape player, thinning is a very important factor. Therefore, if the rotating head device, which is the thickest unit in the device, increases in size, it becomes an obstacle to making the device thinner and smaller as described above. If the thickness of the rotating head device is to be reduced, the span between the bearings 2 and 3 must be reduced, which may cause problems such as the outer circumference of the rotating drum 6 as described above. This makes it difficult to achieve high precision.

(2) In the assembly work, an appropriate preload is applied to the inner rings of the bearings 2 and 3 using members such as the preload bushing 17 at room temperature. However, the fixed drum 1, shaft 4, and bearing 2゜3 are made of different materials.
For example, since the fixed drum 1 is made of aluminum alloy, the shaft 4 is made of stainless steel, and the bearings 2 and 3 are made of Fe alloy, the coefficients of thermal expansion of the respective members are different. Therefore, a change in elongation in the axial direction occurs between the fixed drum 1 and the shaft 4 due to temperature changes,
Furthermore, a difference in elongation in the axial direction also occurs between the bearings 2, 3 and the shaft 4. Particularly when a car-mounted tape recorder is equipped with a rotating head device, the temperature inside the car may drop below the freezing point in the winter and rise to around 80°C to 80°C in the summer. , the width of the temperature difference becomes very large. Under such an environment, the difference in the elongation of each member in the axial direction becomes considerably large, and as a result, the preload on the inner rings of the bearings 2 and 3 also changes. In other words, when the axial dimension of the fixed drum 1 becomes smaller relative to the shaft 4, the preload between the bearings 2 and 3 becomes smaller, and conversely, the 7 axial dimension of the fixed drum 1 becomes smaller than the shaft 4. 4, the preload of bearings 2 and 3 becomes excessive. An example of the relationship between the preload of the bearings 2 and 3 and changes in environmental temperature will be explained with reference to the diagram shown in FIG.

As shown in this ti diagram, in an environment where large temperature changes occur, in the bearing mechanism of the conventional rotary head device, the preload on the inner races of the bearings 2 and 3 changes greatly as shown by the broken line. As the internal temperature increases, the bearing preload increases, and the rise in preload slows down at 70°C to 80°C. In such a high temperature state, impressions are formed on the balls of the bearings 2 and 3, causing vibration noise during rotation. On the other hand, if the environmental temperature becomes too low, a radial clearance will occur in the bearing 2.3 due to a decrease in preload, resulting in rolling of the shaft 4, resulting in a disadvantage that highly accurate rotational movement will not be possible.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned conventional problems, and is capable of applying an appropriate preload to the inner ring of a pair of bearings that support a shaft fixed to a rotating drum.
It is possible to increase the rotation accuracy of the rotating drum by preventing this preload from fluctuating due to large changes in environmental temperature, preventing impressions from forming on the balls of the bearing, or greatly changing the radial clearance of the bearing. The purpose of the present invention is to provide a rotary head device that enables the rotation of the head.

[Structure of the invention]

In the present invention, a shaft to which a rotating drum is fixed is rotatably supported by a pair of bearings held by the fixed drum, and a magnet is attached to the rotating drum.

In a rotary head device equipped with a head, one of the bearings is fixed to the shaft, and between this bearing fixed to the shaft and the other bearing, there is a groove for applying preload to the inner ring of the bearing. It is characterized by the inclusion of a preload spring. Further, the bearing fixed to the shaft is, for example, a bearing integrated with the shaft, which is composed of a ball that contacts the outer circumferential surface of the shaft and an outer ring located outside of the ball, and the above-mentioned one of the preload spring. The end on the body bearing side is in contact with a ring fitted to the shaft.

[Operation of the present invention]

In the present invention, one of the pair of bearings is fixed to the fixed drum by press fitting, etc., this bearing is fixed to the shaft, and a preload spring is interposed between this bearing and the other bearing. This preload spring applies an appropriate thrust load to the inner ring of each bearing. The shaft and rotating drum are made of materials with different coefficients of thermal expansion, and even if there is a difference in the axial elongation of each member due to changes in environmental temperature, this difference in elongation will affect the length of the preload spring. The preload on the inner ring of the bearing is always maintained at a constant value by absorbing the change.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to FIGS. 1 to 4.

FIG. 1 is a half-sectional view showing a rotary head device according to the present invention;
Fig. 2 is a half-sectional view showing the shaft and the bearing integrated with it, Fig. 3 is a plan view schematically showing an in-vehicle magnetic regenerator equipped with a rotating helad device, and Fig. 4 is a side view thereof. It is a diagram.

As shown in FIG.
2 is fixed. This bearing 22 includes a ball 22a that contacts a recess 21a formed in the upper part of the shaft 21,
The outer ring 22b is located on the outer periphery of the outer ring 22b.

In addition, a spring retaining ring 2 is located slightly below the bearing 22.
3 is fixed.

As shown in FIG. 1, a sleeve 31 is fixed to the upper part of the shaft 21, and a rotating drum 32 is further fixed to this sleeve 31. Further, on the inner diameter portion of the fixed drum 33 located on the lower side, a step 33a is formed at the upper end and a step 33b is formed at the lower end. The bearing 22, which is integral with the shaft 21, is fixed to the step 33a at the upper end by means such as press fitting or shrink fitting. A preload spring 36 is mounted on the center of the shaft 21, and its -
The E end abuts a spring stop ring 23 fixed to the shaft 21. A preload collar 35 is mounted on the lower part of the shaft 21, and the lower end of the preload spring 36 is received by the preload collar 35. Further, another radial bearing 34 is inserted into the lower part of the shaft 21, and this bearing 34 is fixed to the step 33b at the lower end of the fixed drum 33 by means such as press fitting or shrink fitting. Since the preload spring 36 is interposed between the spring retaining ring 23 and the preload collar 35 with a predetermined elastic force, a predetermined inner ring preload is applied to the upper bearing 22 and the lower bearing 34 by this elastic force. It is being

Further, a head support member 37 is fixed to the lower surface of the rotating drum 32, and a magnetic head 38 is fixed to this head support member 37. Further, while the zero-rotation drum 32 is rotating, a rotor transformer 41 is fixed to the rotating drum 32, a stator transformer 42 is fixed to the fixed drum 33, and the one-car transformers 41 and 42 face each other at a minute interval.
A signal read by the magnetic head 38 is led out through both transformers 41 and 42.

A magnet support member 43 is fixed to the lower part of the shaft 21, and a yoke 4 is attached to this magnet support member 43.
A rotor magnet 45 is fixedly installed via 4. Further, a substrate 46 is fixed to the lower end of the fixed drum 32, and a stator coil 47 is fixed to this substrate 46. When a current is applied to the stator coil 47, the rotor magnet 45 is driven to rotate, and the shaft 21 and the rotating drum 32 are rotated together with this.

In this rotary head device, the bearings 22 and 34 are fixed to the upper and lower ends of the inner diameter portion of the fixed drum 33 by press fitting or the like. The preload of each bearing 22 and 34, that is, the load in the thrust direction on the inner ring is applied to the preload spring 3.
0 set by the elastic force of 6 (usually a shirt) 2
1 and the fixed drum 33 are made of different materials. For example, the shaft 21 is made of stainless steel, and the fixed drum 33 is made of aluminum alloy. In such a case, there will be a difference in the elongation of the shaft 21 and the fixed drum 33 in the seven axial directions due to changes in the environmental temperature. Since the bearing 34 is fixed to the fixed drum 33, differences in elongation due to temperature changes are absorbed by slight sliding between the inner ring of the bearing 34 and the shaft 21. Further, the preload of the bearings 22 and 34 is set by the elastic force of the preload spring 36, but if the fixed drum 33 expands or contracts due to temperature changes, the amount of deflection of the preload spring 36 will also change. However, since this change in the amount of deflection is minute,
This means that it has almost no effect on the change in the elastic force according to the spring coefficient of the preload spring □. Therefore, even if the environmental temperature changes, the preloads on the bearings 22 and 34 will hardly change. This change in preload is as shown by the solid line in the graph of FIG. Since there is almost no change in preload regardless of temperature changes, it is possible to prevent the formation of impressions on the bearing balls due to excessive preload and the generation of radial clearance between the bearings 22 and 34 due to insufficient preload.

In addition, in the illustrated embodiment, the upper bearing 22 and the shaft 21 have an integrated structure, so the shaft 21 and the bearing 2
The concentricity with the outer ring 22b of No. 2 can be maintained at a high level. Therefore, after assembly, the axial runout of the rotating drum 32 in the radial direction can be reduced, and highly accurate rotation can be guaranteed.

Next, an example of a vehicle-mounted magnetic reproducing device equipped with a rotary head device will be explained with reference to FIGS. 3 and 4. FIG. Reference numeral 51 is a chassis, and the rotary head device 3 is mounted on this chassis 51.
0 is equipped. Further, 54 is a loading mechanism for loading the cassette 60 onto the chassis 52. The tape T in the loaded cassette 60 is pulled out by tape pull-out members 52 and 53 on the chassis 51, and wound around the outer circumferences of the rotating drum 32 and the fixed drum 33 at an angle. Then, the rotary drum 32 is driven to rotate, and the recording surface of the tape T is scanned by the magnetic head 38. In addition, the magnetic head 38
The read signal is transmitted from the rotor transformer 41 to the stator transformer 42 and taken out to the outside.

In the illustrated embodiment, the upper bearing 22 and the shaft 21
Although the bearing 22 has an integrated structure, it is also possible to use a separate bearing from the shaft 21 and fix it to the shaft 21 with a ring or the like.

〔Effect of the invention〕

As described above, according to the present invention, the following effects can be achieved.

(1) Since the preload of the bearing is set by the preload spring, even if the elongation of the fixed drum changes due to changes in the environmental temperature, there will be no major change in the preload of the bearing, which will prevent damage to the bearing. It becomes possible to prevent the occurrence of radial clearance. Therefore, it is particularly effective when installed in equipment that is subject to large changes in environmental temperature, such as in-vehicle magnetic reproducing devices.

(2) Unlike the conventional example shown in Fig. 6, there is no need to provide the preload collar 15, preload ring 16, or preload bush 17 below the lower bearing, so the overall thickness of the 5-turn head device can be reduced. , it will be possible to contribute to thinner devices. Furthermore, since the preload collar 15 and the like are not required, the spans of the bearings 22 and 34 can be made longer, thereby making it possible to reduce the rotational runout of the shaft and the rotating drum in the radial direction, thereby increasing the rotational accuracy.

[Brief explanation of drawings]

Fig. 1 is a half-sectional view showing the bearing mechanism of the rotating head device according to the present invention, Fig. 2 is a half-sectional view showing the shaft and the bearing integrated therewith, and Fig. 3 is a half-sectional view showing the bearing mechanism of the rotating head device according to the present invention. A plan view showing the magnetic reproducing device for use, FIG. 4 is a side view thereof,
FIG. 5 is a diagram showing changes in bearing preload due to temperature changes, and FIG. 6 is a half-sectional view showing a conventional rotary head device. 21...Shaft, 22...Integrated bearing, 22a
... Ball, 22b ... Outer ring, 23 ... Spring retaining ring, 31 ... Sleeve, 32 ... Rotating drum, 33 ... Fixed drum, 35 ... Preload collar, 36 ... preload spring. Figure 5, Figure 6, ``Procedural amendment (old style) 1985'\'' September 11, 1985 Patent Application No. 162476 Title of invention Rotating head device Person who makes the amendment

Claims (2)

[Claims] (1) A rotating head device in which a shaft to which a rotating drum is fixed is rotatably supported by a pair of bearings held by the fixed drum, and the rotating drum is equipped with a magnetic head. One of the bearings is fixed to the shaft, and a preload spring is interposed between this bearing fixed to the shaft and the other bearing to apply preload to the bearing in the thrust direction. Rotating head device. (2) The bearing fixed to the shaft is a bearing that is integrated with the shaft and is composed of a ball that contacts the outer circumferential surface of the shaft and an outer ring that is located outside of the ball, and the above-mentioned integrated type of preload spring. 2. The rotary head device according to claim 1, wherein the end on the bearing side is in contact with a ring fitted to the shaft.