JPH076336A - Rotary head device - Google Patents

Abstract

PURPOSE:To make a rotary head device low in cost and light in weight and to improve assembling workability by fixing an upper side drum independently from a lower drum and providing a notch part in the part of its outer peripheral wall. CONSTITUTION:An upper drum 2 is fixed on the upper part of a central shaft 1 having a specified distance from a lower drum 3 via a fixture 10. The central shaft 1 is fixed on the bottom surface of the lower drum 3 with pressure. Then, the notch part 160 is provided on the part of the outer peripheral wall of the upper drum 2. Thus, the rotary head device is miniaturized and reduced in weight and assembling workability and accuracy are easily improved. Further, since the notch part 160 is provided on the side surface of the upper drum 2, the inspection, and repairment, etc., of a rotary part are facilitated and a gap between rotary trances 14 and 15 is easily adjusted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary head device, and more particularly to a rotary head device suitable for recording / reproducing a magnetic signal to / from a recording medium such as a cylinder motor of a video tape recorder (hereinafter abbreviated as VTR). .

[0002]

2. Description of the Related Art In a conventional rotary head device having an upper drum fixed, generally, as described in JP-A-55-150125, the upper drum is fixed to a lower drum by a connecting member on the outer peripheral side surface, and The outer peripheral surface of the upper drum has a structure in which the entire circumference is left as it is.

[0003]

The conventional structure of the rotary head device described above has a problem that the device is downsized and lightened, and it is difficult to process the coil terminal of the rotary transformer.

An object of the present invention is to provide a fixed shaft type rotary head device which is small in size and light in weight and has good workability in assembling.

[0005]

In order to achieve the above object, in a rotary head device of the present invention, a rotary member having a head, a rotary transformer and a motor are provided in an axial intermediate portion of both fixed upper and lower drums. In a rotary head device for rotating the head around a fixed central axis, the upper drum is fixed to the fixed central axis independently of the lower drum together with a fixed side member of the rotary transformer via a mounting means, and A part of the outer peripheral side wall is cut out.

[0006]

EXAMPLES The present invention will be described below based on examples.

FIG. 1 is a view showing an embodiment of the present invention, FIG. 2 is a structural view of a stator coil in the structure of the embodiment, and FIG. 3 (a) is a magnet for the same FG (frequency generator for speed detection). Fig. 3 (b) is a magnetic pole surface diagram of Fig.
FIG. 4 is a rotary transformer structure and its wiring diagram in the first embodiment. In the figure, the central shaft 1 is fixed to the center of the bottom surface of the lower drum 3 by press fitting or the like. The upper drum 2 is the shaft 1
Is fixed to the central shaft 1 via a fixing piece 10 at a predetermined distance from the lower drum 3 in the upper part of the. A magnetic head rotation including a head mounting structure 78 having a magnetic head 8 (8 ') mounted on its outer peripheral portion in an intermediate space between the upper and lower drums, a rotary structure 75, a rotary sleeve 4, a drive motor, a rotary transformer and the like. It has a built-in drive unit. The rotary sleeve 4 has bearings 5 and 5'at the upper and lower ends of its center, and is rotatably engaged with the shaft 1 via the bearings 5 and 5 '. A rotary structure 75 is fixed to the upper end of the rotary sleeve 4 with screws 12. Further, a head mounting structure 78 and a motor rotor (rotor magnet 18, rotor yoke 19) are fixed on the rotary structure 75. The magnetic head 8 and the rotary side yoke 15 of the flat rotary transformer are fixed on the head mounting structure 78. A yoke 22 to which an FG magnet 100 and a head position detecting magnet (tuck magnet) 50 are fixed is fixed to a lower end portion of the rotary sleeve 4 with a screw 23. The magnetic poles of the rotor magnet 18 face the yoke 22 and form a motor magnetic circuit therebetween. An annular stator coil 21 is provided between the rotor magnet 18 and the yoke 22. The outer peripheral portion of the stator coil is fixed to the inner peripheral side wall of the lower drum 3 with screws 12. The stator coil 21 has an air core (no iron core in the coil pole) structure as shown in FIG. It was done.

In this embodiment, the rotor magnet 18 has eight magnetic poles and is driven in three phases. Therefore, in this embodiment, the stator coil 21 has a plane arrangement of two coil poles per phase and a total of six coil poles. The coil poles and the sensors 40a, 40b, 40c are connected in advance to the connection pattern on the surface of the thin sheet-like wiring board 25,
This is molded by plastic molding into a rigid rigid surface.
Reference numeral 120 denotes a small hole for screwing for fixing this to the lower drum, 70 is a lead portion of the substrate, and 110 is a plastic molding portion. On the inner peripheral bottom surface of the lower drum 3, FG
The substrate 95 is fixed with screws or the like. FG magnet 10
0, the structural example of the FG substrate is shown in FIG.

FIG. 1A is a magnetic pole surface view of an FG magnet,
FIG. 3B is an FG pattern diagram of the FG substrate. The FG magnet 100 fixed to the yoke 22 is magnetized in the circumferential direction into multiple poles more uniformly than the rotor magnet 18, while the FG substrate 95 has a radial conductor pattern 130 having a pitch corresponding to this magnetizing pitch. Are formed on the surface. Further, the tack magnet 5 is provided on the FG substrate surface.
A sensor (tack sensor) 41 that generates a position signal of the magnetic head 8 by detecting a magnetic field of 0 is also fixed to the wiring. A second motor wiring board 25 'is fixed to the outer bottom surface of the lower drum 3, and the terminals of the stator coil 21, the sensors 40a to 40c, the terminals of the FG pattern 130, and the like are provided on the surface. The terminal of the tack sensor 41 is connected, and the FG signal amplifier circuit 111, the motor drive circuit 112, and the like are also fixedly wired. Reference numeral 36 is a lead wire portion, which is further connected to a servo circuit, a power supply, or the like. Three
Reference numeral 8 is a connector. The diameter of the upper end of the rotating sleeve 4 is
The size is smaller than the inner diameter of the annular stator coil 21, and after the rotary sleeve 4 is mounted on the shaft 1, the stator coil 21 can be mounted and fixed in the lower drum 3. The fixed side yoke 14 of the flat rotary transformer is bonded and fixed to the lower end surface of the fixed piece 10 at the upper end of the shaft 1, and
The upper drum 2 is fixed to the upper end surface with screws 12.
The fixed-side yoke 14 of the rotary transformer is opposed to the lower-side rotated yoke 15 with a predetermined narrow gap therebetween, and is capable of transmitting / receiving the recording / reproducing signal of the magnetic head 8 (8 '). . A substrate 24 is provided on the upper surface of the fixed side yoke 14, and the ends of the windings inside the fixed side yoke 14 are connected. Further, the signal amplification circuit 10 is provided on the substrate 24.
1 (reproduction system), 101 (recording system) and other signal processing circuits 103 are mounted and wired. The terminal portion of the board 24 is led out to the outside from a notch 160 in the side wall of the upper drum 2, and is connected to a signal processing circuit at a subsequent stage from here. Each winding in the rotary side yoke 15 of the rotary transformer is connected to a magnetic head 8 (8 ') fixed to the upper surface of the head mounting structure 78 and the lower surface of the outer peripheral portion of the same. The board 28 is a connection board for this purpose. The head mounting structure 78 is fixed to the rotating structure 75 with the screw 12 at the outer peripheral edge thereof, that is, outside the rotating transformer yoke 15, and is integrated with the head 8 (8 ′), the rotating transformer yoke 15, etc. with respect to the rotating structure 75. It can be attached to and detached from.

The plane structure of the rotary transformer yoke 15 is shown in FIG.
It shows in (a). A substrate 85 is provided on the inner peripheral surface of the yoke 15.
And a terminal 66a of the conductor short-circuiting ring 65 provided between the channel windings 62 and 63 in the yoke 15.
66b is connected to the pattern conductor on the same substrate 85, and at the same time, the earth brush 55 'is also connected and fixed. The ground brush 55 'is electrically connected to the short-circuit ring terminals 66a and 66b at the pattern portion on the substrate 85. The tip of the earth brush 55 'is in contact with the outer circumference of the shaft 1. 6 in the figure
Reference numerals 0a to 60b are grooves for accommodating the channel windings, the short-circuit ring, and the terminals. The winding structure in the fixed side yoke 14 of the same transformer is the same as that in the rotating side yoke 15, and a short circuit ring 65 'is provided between the channel windings 62' and 63 '. The terminal is connected to the fixing piece 10 via the substrate 24 or directly. In this structure, the fixing piece 10 is made of a conductive material such as aluminum or brass.

FIG. 4B shows a connection diagram of a regeneration system of the rotary transformer winding. The first channel magnetic head 8 is connected to the inner winding 62 of the rotary side yoke 15 of the rotary transformer, and the second channel magnetic head 8'is connected to the inner yoke 63 of the yoke 15.
It is connected to the. Short circuit ring 65 in the rotary side yoke 15
Is grounded via the earth brush 55 'and the shaft 1.
In the fixed side yoke 14, the first channel winding 62 'connects the terminal to the first channel amplifier circuit in the amplifier circuit 101, and similarly, the second channel winding 63' connects to the first channel amplifier circuit in the amplifier circuit 101. It is connected to a 2-channel amplifier circuit. Further, the short-circuit ring 65 ′ in the yoke 14 is the fixed piece 10,
It is electrically grounded via the shaft 1. Short circuit ring 65,6
5'is between the channel windings 62 and 63 and 6 respectively.
It is grounded to greatly reduce the amount of crosstalk between 2'and 63 '. At the time of recording, the amplifier circuit 102 amplifies the signal from the preceding circuit for each channel and supplies the amplified signal to each magnetic head through each channel winding of the rotary transformer.

With this structure, the magnetic head 8 is driven by the motor.
(8 ') is rotated and the surface of a recording medium such as tape running on the side surfaces of the upper and lower drums 2 and 3 is scanned by the head 8 (8') to record / reproduce signals. The rotation speed is controlled by the FG signal generated on the FG pattern 130 of the FG substrate 95 due to the change in the magnetic field of the FG magnet 100. The rotation phase of the recording medium is controlled by detecting the signal of the tack sensor 41 and comparing it with the reference signal.

According to the structure of this embodiment, (1) an air-core coil is used as the stator coil 21,
Since the yoke 22 is rotated integrally with the rotor magnet 18, iron loss does not occur in the stator. Therefore, the motor can be made highly efficient. Further, since no magnetic material is used in the stator, no attractive force acts on the rotor magnet 18. Therefore, since no cogging torque is generated, smooth rotation with low torque ripple can be achieved.

(2) Since the attraction force of the magnet 18 to the bearing can be eliminated, the friction of the bearing can be reduced and the motor can be made low loss and highly efficient in this respect as well. It is also possible to prevent damage to parts such as bearings during assembly.

(3) Since the stator coil 21 is molded by the plastic mold, a thin sheet-like substrate can be used as the substrate 25 instead of the rigid thick substrate, so that the entire thickness of the stator is approximately equal to the coil. It can be equal to 21 winding thicknesses. Therefore, it is easy to obtain a strong magnetic field by reducing the electromagnetic gap (gap between the magnetic pole surface of the magnet 18 and the yoke 22).

Further, when the coil is formed, the positioning of the coil poles is performed using a mold die, so that the coil pole arrangement accuracy can be improved. Furthermore, even a complicated stator structure can be easily manufactured at low cost.

(4) Since the FG substrate 95 is fixed to the bottom surface of the lower drum 3 with high precision, the FG with high precision is provided.
A signal can be obtained and a high gain control system can be constructed.

(5) Since the magnetic poles of both the rotor magnet 18 and the FG magnet 100 are downward, magnetic noise can be greatly reduced for the tape, the head 8 (8 '), the rotary transformers 14 and 15, etc.

(6) The substrate 24 is provided on the rotary transformer 14, and the amplifier circuits 101 and 102 and the signal circuit 10 are provided on this surface.
Since 3 and the like are provided, the lead wire portion can be short-circuited, noise can be reduced, and S / N of the signal system can be increased.

(7) Since the short-circuit ring in the rotary transformer is grounded, crosstalk between channels can be greatly reduced.

(8) Since the second motor substrate 25 'is provided and the FG signal amplifier circuit 111, the drive circuit 112, etc. are provided on this surface, the S / N of the FG signal can be improved and the structure is made compact. it can.

(9) The upper drum 2 has a notch 1 on its side surface.
Since it has 60, the rotating part can be partially exposed, and it is easy to inspect and modify the rotating part.
It is easy to adjust the gap between them. Further, since the substrate 24 provided on the transformer 14 can be pulled out to the outside, the terminal processing of the coil and the connection work to the outside can be easily performed.

(10) Since the ring-shaped convex portion 165 is provided on the outermost peripheral portion of the head mounting structure 78, a dynamic balance correcting weight or the like can be easily fixed to the inside thereof. It can be done easily in a short time.

(11) Since the substrate 24 is provided on the rotary transformer 14 and the rotary transformer 14 is fixed to the fixed piece 10, the rotary transformer is installed in the regular position even when the upper drum 2 is not installed. It can be fixed and the performance can be checked.

(12) In the gap between the upper and lower drums on the tape running surface, only a small amount of the chips of the head 8 (8 ') are projected and exposed, and the head mounting structure 78 and the rotating structure 7 are provided.
Since almost all 5 equal rotating parts are built in between the upper and lower drums, the wind noise (air friction noise) generated by the rotating body is extremely small, and the noise can be reduced as a whole. Further, the vibration given to the running tape by the rotating body is extremely small. Therefore, low jitter, low wow and flutter can be realized. Furthermore, since a thin film of air is not formed between the tape and the drum during rotation, the tape does not lift from the drum surface. For this reason, good head touchability with respect to the tape can be obtained, and the head output level and the S / N ratio of the head signal can be greatly improved. It is also possible to reduce the tape tension and the head chip protrusion amount. Therefore, the wear of the head chip and the running friction of the tape can be reduced, the life of the head and the tape can be extended, the motor load can be reduced, and the power consumption can be reduced.

(13) Since the rotational inertia can be reduced, it is possible to start and stop at high speed. Further, since the dynamic imbalance amount can be reduced, the whirling displacement amount of the rotating body can be reduced and the vibration can be reduced, and the like.

FIG. 5 is a view showing another example of the structure of the stator coil 21, which is a structure in which three sheet coils 21u, 21v, 21w having an 8-pole structure (the same number as the number of magnet magnetic poles) are laminated on the substrate 25. Is. 21u is a U-phase coil, 21v is V
Phase coil, 21w is a W phase coil. Each phase coil has a coil pole composed of an eight-pole pattern conductor that overlaps both the front and back sides of the insulating wiring sheet 125, and the front and back conductors are connected by the spot pattern 45 at the coil pole center.
Six poles are connected in series. 120a _{1 to} 120d ₁ , 12
0a _{2 to} 120d ₂ and 120a _{3 to} 120d ₃ are small holes for screw penetration for fixing the entire coil to the inner circumference of the lower drum 3, and 86 is for connecting each phase coil between layers and on the surface of the substrate 25. A conductor pattern, 88 is a conductor pin for connection inserted in a small hole provided in the conductor pattern 86, and 87 is a conductor such as solder for connecting the conductor pattern 86 and the conductor pin 88. The conductor 87 may not be used, and the conductor pattern 86 and the pin 88 may be connected to each other by welding by energizing the pin 88 to connect the layers. Sensor 40 (40a-4
0c) and the tack sensor 41 are provided on the surface of the substrate 25. The sensor is provided outside the coil pole and provided inside or outside the coil.

FIG. 5 (a) is a front view of each sheet, FIG. 5 (b) is a sectional view fixed in the lower drum 3, and FIG. 5 (c).
FIG. 4 is an enlarged view of an interlayer connection part. 86 in FIG.
Reference symbols a to 86f are connection patterns provided on the respective sheet surfaces. With this sheet-shaped coil, the coil conductor is formed into a pattern by a chemical manufacturing method such as etching or plating, so the shape and dimensions of the coil poles can be made highly uniform and highly precise, and the coil pole arrangement accuracy is also extremely high. Can be higher Furthermore, the number of coil poles can be set to be more than the number of magnet magnetic poles. As a result, in the rotary head device using the present sheet coil, it is possible to realize a thin device with low torque ripple, high smoothness and high efficiency. In the figure (a), the sheet 125
Notches 140a, 140b, 140c provided on the outer periphery of the
Are for storing the sensors 40a, 40b, 40c, respectively.

FIG. 6 is a diagram showing still another embodiment of the stator coil 21. In this structure, a through hole 131 for accommodating the coil pole is provided in the surface of the rigid substrate 25, and the coil pole is accommodated in the through hole 131 and fixed by a fixing member 151. The small hole 120 on the outer peripheral portion of the substrate 25 is used. Fix in the lower drum 3. The sensors 40a, 40b, 40c are also inserted and fixed in the small holes in the substrate. On the surface of the substrate 25, coil poles and sensors 40a-4
A terminal connection pattern of 0c is provided so that each connection can be performed on the surface. Further, as a similar example of the structure of the present embodiment, there is also a structure in which a thin sheet-like wiring board 25 ″ and a rigid board 25 are laminated to form a plurality of structures (FIG. 13C). That is, on the thin sheet-like board 25 ″. The coil 21, the sensor 40, and the like are wired, inserted into a predetermined hole on the substrate 25, and fixed by being bonded to the substrate 25 ″. According to these embodiments, the air-core stator can be easily and cost-effectively. A coil can be obtained.

7 to 9 are views showing another embodiment of the rotary head device of the present invention, which has a structure using a fluid dynamic bearing as a bearing. 7 is an overall view of the apparatus, FIG. 8A is an enlarged view of a journal portion of a fluid bearing, FIG. 8B is a plan view of a thrust portion, and FIG. 9 is a stator coil view. Fluid bearing has fixed shaft 1
Two upper and lower parts on the outer peripheral surface of the shaft and the thrust load receiving piece 210
Is formed on the upper surface of the V-shaped shallow groove (herringbone type groove) 200a, 200b, 215.
A second rotary sleeve (sleeve for fluid bearing) 170 is fixed to the center of the first rotary sleeve 4, and the inner peripheral surface and the lower end surface of the second rotary sleeve are opposed to the respective groove portions with a narrow gap. Lubricating fluid such as grease or oil is filled in each narrow gap portion, and the lubricating fluid is drawn into each groove by the rotation of the hydrodynamic bearing sleeve 170 (counterclockwise rotation in the figure) to generate a fluid dynamic pressure in each portion. Fluid bearing sleeve 1
Raise 70. That is, in the journal portion, the dynamic pressure in the radial direction is generated by the grooves 200a and 200b,
Grooves 215 generate axially upward dynamic pressure in the thrust portion. Thus, the shaft 1 and the thrust load receiving piece 21
The bearing sleeve is supported in a non-contact state by means of a fluid with respect to zero. In this structural example, a material having a linear expansion coefficient corresponding to the temperature characteristic of the fluid viscosity is used as the thrust load receiving member 210, and even if the fluid viscosity decreases due to the temperature increase and the thrust dynamic pressure decreases, the flying height decreases. The expansion of the receiving piece 210 compensates for the variation and keeps the height position of the rotor constant so that the magnetic head 8 can always be kept at a predetermined position. The upper, middle, and lower steps of the fluid bearing sleeve 170 are provided with recesses, respectively, so that fluid can be held therein. The structure in which the FG magnet 100 is provided on the lower surface of the yoke 22 is the same as that of the embodiment structure shown in FIG. A thin magnetic material plate 96 is provided below the FG substrate 95. By providing the magnetic material plate 96, a thrust attraction force is generated between the magnetic material plate 96 and the FG magnet 100 to pull the rotating portion downward. As a result, even if the posture of the device is turned over or turned upside down, the rotating portion can always be held at the constant height position. Further, since the magnetic flux from the FG magnet 100 interlinking with the FG pattern on the FG substrate 95 can be increased, the FG signal output level can be improved. Further, since the uniformity of the distribution of the magnetic flux can be improved, the accuracy of the FG signal can be improved. 140
Is a small hole for removing air in the fluid bearing. According to this structure using the fluid bearing, in addition to the effects of the above-described embodiment, (1) the rotating portion can be supported in a non-contact manner with respect to the fixed portion,
Vibration during rotation can be significantly reduced.

(2) Since the outer diameter of the bearing housing portion (fluid bearing sleeve 170, rotary sleeve 4) can be reduced, the size of the electromagnetic portion of the motor portion can be increased and the motor performance can be improved.

(3) The life of the bearing can be extended.

(4) The cost of the bearing can be reduced.

The following effects can be obtained. A thin sheet substrate 25 having a lead-out portion 70 is used for the stator coil 21 portion, and the tack sensor 41 is also fixed by wiring. This coil is also molded by plastic molding.

FIGS. 10 and 11 are views showing still another embodiment of the present invention, in which two rotor magnets (first rotor magnet 1 are used as a DD motor unit structure.
8 and the second rotor magnet 18 '), and the air-core stator coils 21 are vertically sandwiched with the opposite poles facing each other. FIG. 10 is an overall structural diagram, FIG.
(A), (b) is a rotor magnet magnetic pole surface view, FIG.
(C) is a magnetic pole opposing figure. In the figure, the magnets 18 and 18 'are fixed to the rotor yokes 19 and 19', respectively, and attached to the lower surface of the rotary structure 75 and the lower surface of the rotary sleeve 4. In the structure of the present embodiment, the first rotor magnet 18 is used as a main magnet and has a large size.
Although the rotor magnet of (1) and (2) have a small size as an auxiliary magnet, they may have the same size or may have the opposite size relationship. Further, the material of each magnet may be a ferrite magnet or a rare earth magnet or the like for both 18 and 18 '. Alternatively, a combination configuration in which one is a ferrite magnet and the other is a rare magnet, etc. may be used. Using ferrite as the main magnet reduces the cost. The FG magnet 10 is provided on the back surface of the rotor yoke 19 '.
0 is fixed. The FG substrate 95 is provided on the bottom surface of the lower drum 3 so as to face the FG magnet 100. As the stator coil 21, the one molded by the same plastic mold as that of the first embodiment is used. The structure of the other parts is almost the same as that of the first embodiment. According to the structure of the present embodiment, (1) since two rotor magnets of opposite poles are used, the magnetic path length of the magnet magnetic circuit can be shortened, and the low energy product and low cost of a thin magnet or ferrite can be achieved. Even with a magnet, a strong magnetic field can be easily obtained. Therefore, the motor constant value can be increased to improve the stability against load and the cost can be reduced.

(2) The attraction force of the rotor magnets 18 and 18 'does not act on the bearings 5 and 5'. Therefore, the bearing can be lightly loaded and the friction torque can be greatly reduced.

(3) Since the uniformity of the magnetic field distribution between the two magnet magnetic poles can be increased, the amount of interlinking magnetic flux with the stator coil can be increased and motor efficiency can be improved. Further, it is possible to mitigate the deterioration rate of the motor performance such as the torque ripple increase due to the fixed displacement of the stator coil in the gap. Therefore, the assembling work and the quality control are easy.

(4) Magnet Since the magnetic circuit has a high permeance, magnetic leakage to the outside is extremely small. Therefore, it is possible to reduce noise on the rotary magnetic head, the signal system circuit, and the like.

(5) First rotor magnet 18 and second rotor magnet 18
In the rotor magnet 18 ', the magnetic field distribution and the amount of magnetic flux can be changed by combining the dimensions, materials, magnetic pole shapes, etc., to achieve effects such as high efficiency, low torque ripple, and low cost. To be

In the above embodiments, the motor is the sensor 40.
Although the DD motor having a 3-phase 8-pole configuration using a to 40c is used, a motor having a phase number, a pole number, a sensor number, or a sensor configuration other than this may be used. Alternatively, the sensor may have a motor configuration in which it is not used at all. Further, a magnetic material may be used in a part of the inside of the stator coil, and particularly in the case of the fluid bearing structure, an attraction force for supporting the rotor may be generated between the magnet and the rotor magnet. Further, in the hydrodynamic bearing structure, a herringbone-shaped groove is provided on the lower surface of the fixed piece 6 in the structure in which the hydrodynamic pressure is generated also in the upper direction of the hydrodynamic bearing sleeve 170 in the thrust direction (downward direction in the drawing), for example, in FIG. The structure may be such that a fluid dynamic pressure is generated between the sleeve 170 and the upper end surface of the sleeve 170. Also,
Between the upper end surface of the sleeve 170 such as the upper end surface of the rotating body and the lower end surface of the fixed portion such as the fixed piece 6, a magnet having magnetic poles of the same polarity opposed to each other is fixedly provided on each side, and the mutual repulsion force is utilized. There is also a structure that obtains downward thrust force. Further, the structure may be such that the magnetic plate 96 is not included in the motor unit.

[0041]

According to the present invention, (1) a compact, lightweight and compact structure can be achieved.

(2) The workability and accuracy of the assembling can be easily improved.

(3) Since the side surface of the upper drum has a missing portion, it is easy to inspect and correct the rotating portion, and it is also easy to adjust the gap between the rotating transformers. Further, since the wiring board provided on the transformer can also be pulled out to the outside, it is possible to obtain effects such as facilitating terminal processing of the coil and connection work to the outside.

[Brief description of drawings]

FIG. 1 is a sectional view of an essential part of an embodiment of the present invention.

FIG. 2 is a diagram showing a stator coil structure used in the embodiment of FIG.

3 is a diagram showing an FG portion structure used in the embodiment of FIG.

4A and 4B are a plan view and a connection diagram of a rotary transformer unit used in the embodiment of FIG.

FIG. 5 is a diagram showing another structural example of a stator coil.

FIG. 6 is a diagram showing another structural example of a stator coil.

FIG. 7 is a diagram showing another embodiment of the present invention.

FIG. 8 is a structural view of a bearing portion in another embodiment of FIG.

9 is a structural diagram of a coil used in another embodiment of FIG.

FIG. 10 is a diagram showing still another embodiment of the present invention.

11 is a diagram of a rotor magnet used in the embodiment of FIG.

[Explanation of symbols]

 1 ... Fixed shaft, 2 ... Upper drum, 3 ... Lower drum, 4 ... Rotating sleeve, 14, 15 ... Rotating transformer, 18, 18 '... Rotor magnet, 21 ... Stator coil, 22 ... Yoke, 95 ... FG Substrate, 100 ... FG magnet.

Claims (1)

[Claims] 1. A rotary member having a head, a rotary transformer, and a motor are provided in an axial intermediate portion of both fixed upper and lower drums,
In a rotary head device for rotating the head around a fixed central axis, the upper drum is fixed to the fixed central axis independently of the lower drum together with a fixed side member of the rotary transformer via a mounting means, and A rotary head device, characterized in that a part of the outer peripheral side wall is cut out.