JPS61104414A - Rotary head - Google Patents

Abstract

PURPOSE:To attain the high performance and also to improve the overall assembling workability with a rotary head device, by incorporating the 1st and 2nd rotary structures, a fluid dynamic pressure bearing part, a rotary transformer and a drive motor into a space enclosed by at least an upper drum. CONSTITUTION:A rotary side yoke 7 of a rotary transformer is fixed to the upper surface side of the 1st rotary mechanism 3 together with a rotor (consisting of a rotor magnet 12 and a rotor yoke 13) of a direct-coupled drive motor fixed to the lower surface side respectively. While a fixed side yoke 8 of the rotary transformer is fixed to the lower side surface of a disk 9 to which an upper drum 10 is fixed. A motor stator is fixed to the bottom part inside a lower drum 11. Both the rotary transformer and the drive motor are formed flat. The outer diameters of both yokes 7 and 8 are set smaller than the inner diameter of the 2nd rotary structure 4 containing a video head 6. Thus the structure 4 can be loaded and unloaded easily for exchange of the head 6 even with the rotary transformer incorporated.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a rotary head device for a VTR, and particularly to a rotary head device for a VTR.
The present invention relates to a structure suitable for reducing noise and improving contact between a video head and a tape.

[Background of the invention]

An example of a known structure of a rotary head device using a fluid dynamic bearing is the structure described in Japanese Patent Laid-Open No. 19521/1983. In this structure, the video head is fixed and integrated with the upper drum and is driven by a DD motor.A bearing housing is provided on the rotating structure side that includes the upper drum on which the video head is mounted, and the shaft is fixed at the center of the lower drum. A fluid dynamic pressure is generated between the shaft surface and the inner surface of the housing. In this structure, since the upper drum is rotated integrally at the same speed as the video head, the air friction on the upper drum surface is large and the air flow noise (wind noise) is high.
2) The rotational vibration of the upper drum impedes contact between the tape and the head, causing jitter and other deterioration in VTR performance. Furthermore (3
) Since a thin film of air is likely to form between the upper drum surface and the tape surface, the tape tends to float, which tends to reduce the output performance of the head. Moreover, (4) the tape surface is easily damaged because the drum slides on the tape surface. Signal S/ due to sliding noise
N also decreases. (5) Disadvantages include that tape running performance is easily affected by ambient humidity conditions and the top surface of the upper drum. These problems become particularly noticeable when the rotating structure is rotated at high speed.

[Purpose of the invention]

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art, and to provide high performance such as low vibration, low noise, low jitter, and low wah/7tet, as well as easy video head replacement and maintenance, and high overall installation workability for VTRs. To provide a rotating head device.

[Summary of the invention]

In order to achieve the above object, the rotating head device of the present invention has the following features: (1) the shaft is fixed at the center of the lower drum and the upper drum is fixed at the upper end of the shaft; and 2) the upper drum is separated from the rotating structure to which the video head is fixed. 3) The rotating structure is a composite structure divided into at least two parts, and the first rotating structure is rotatable about a central fixed axis via a fluid dynamic pressure bearing. 4) The second rotating structure is fixed to the outer periphery of the first rotating structure, and the video head is fixed to it to integrate it, and the second rotating structure is easily and precisely mounted on the rotating structure of $1 from above. 5) The electronic circuit for rotating transformer signal processing is installed in the conductor close to the rotating transformer, such as by being built into the upper and lower drums. (1) and (2) can significantly improve the contact of the video head with the tape and significantly reduce rotational noise, (3) can significantly reduce vibration, and (4) makes it easier to replace and maintain the video head. It is extremely easy to use and can especially improve serviceability.
), it is possible to improve the S/N of the video signal and improve the image quality.

[Embodiments of the invention]

The present invention will be explained below based on examples.

FIG. 1 shows a first embodiment of the rotary head device of the present invention, and a second embodiment of the rotary head device of the present invention.
The figure is an enlarged structural diagram of the G-r-□ null bearing part in the same embodiment, #! Figure 3 is an enlarged structural diagram of the thrust receiving section. A shaft 1 is fixed to the center bottom surface of a lower/side drum 11, and an upper drum 10 is fixed to the upper end of the shaft 1 via a disk 9. The video rod 6 is fixed to the outer periphery of the second rotating structure 4 via a rod base. The second rotating structure 4 has an annular structure and is fixed to the outer periphery of the fal rotating structure 3 with screws or the like. The first rotating structure 3 is rotatably engaged with the shaft 1 via a bearing that utilizes fluid dynamic pressure. The fluid dynamic bearing section consists of a journal section and a thrust section. The journal part is provided with a dogleg-shaped narrow groove (herringbone-shaped group) of a fluid dynamic pressure generation layer on the outer peripheral surface of the shaft 1 (Fig. 2).
A small gap is formed between the rotating structure 3 and the inner circumferential surface of the collar material 14 fixed to the inner circumference.

The thrust portion is formed between the lower end surface of the collar material 14 and the surface of the thrust receiving material 20 provided facing the lower end surface.

A spiral narrow groove (spiral group) is provided on the surface of the thrust receiving member 20 (FIG. 3) so that fluid dynamic pressure is generated also in this portion by rotation of the rotating structure 3. The journal section generates fluid dynamic pressure in the radial direction, and the thrust section generates fluid dynamic pressure in the axial direction.

arise. In this embodiment, a rotating transformer, a rotating structure, and a motor are arranged in this order from above in a space surrounded by an upper drum and a lower drum. A rotating side yoke 7 of a rotary transformer is fixed to the upper surface side of the first rotating structure 3, and a rotor (consisting of a rotor magnet 12 and a rotor meeter 13) of a direct drive motor is fixed to the lower surface side. It is. A fixed yoke 8 of the rotary transformer is fixed to the lower surface of a disk 9 to which an upper drum 10 is fixed, and a motor stator is fixed to the bottom of the inner surface of the lower drum 11.

Both the rotary transformer and the motor have a flat shape. The outer diameter of the rotating yoke 7 and fixed yoke 8 of the rotary transformer is smaller than the inner diameter of the second rotating structure 4 on which the video head 6 is mounted. With this structure, even when the rotary transformer is installed, the video head 6 can be easily replaced by attaching and detaching the second rotary structure 4. An electronic circuit 42 for video signal processing such as an amplifier circuit connected to the channel winding of the fixed side yoke 8 of the rotary transformer and a wiring board 51 are provided on the back surface of the fixed side yoke 8 and are surrounded by a disk 9 and an upper drum 10. . Further, it is connected to an external circuit by a connector 45 and lead wire 44. The flat motor stator is formed by a flat coil 15, a stator yoke 16, and a sensor 17.
It is fixed opposite to the magnetic pole face of. 61 is a magnetic shielding material. The sensor 17 is a magnetic field detection type element that detects the magnetic field of the magnetic pole face of the rotor magnet 12, and in this structure, it is inserted into a small hole or notch of the stator yoke 16 and fixed therein.

The motor wiring board 50 is fixed to the external lower surface of the lower drum 11, and allows terminal connections of the stator filter 15, the sensor 17, and the motor drive electronic circuit components 40, 41 to be made here. It is. Furthermore, connection to an external electronic circuit is made by a connector 45 and a lead 1s43. The fluid for fluid dynamic pressure bearing 100 is applied to each of the recesses 30, 31, 30, 31, 31, 31, 31, 31, 31, 31, 31, 31, 31, 20, 20, 31, 20, 30, 31, 30, 30, 30. Maintain and replenish a sufficient amount for 32 hours. In particular, a lid 60 is provided on the recess 30 to prevent leakage due to centrifugal force during rotation. 32 also has the effect of reducing fluid friction. Fluid 1
00 may be used depending on the part, such as using different types for the journal part and the thrust part. The first and second rotary structures 3 and 4 are rotated by a direct motor, and the video head 6 is helically scanned over the surface of the video tape that slides on the side surfaces of the upper drum 10 and the lower drum 11. The rotating structure 3 floats on @1 and the thrust receiving member 20 due to fluid dynamic pressure and is supported in a non-contact state. The fluid 100 flows into each group at high speed and generates dynamic pressure by the pumping action. The fluid dynamic pressure value has a maximum distribution at the apex of the herringbone group 2-1 (the doglegged apex) in the journal portion, and a maximum distribution at the innermost diameter point of the spiral group 2-4 in the thrust portion. The dynamic pressure value is proportional to the product of the viscosity of the fluid 100, the rotational angular velocity of the rotating part, and the fourth power of the radius of the rotating sliding surface, and is inversely proportional to the square of the clearance of the rotating sliding surface.

Lubricating fluids for generating dynamic pressure include oil, grease, magnetic fluid, air, and the like. If the thrust receiving material 20 is made of a material, shape, and size that has temperature expansion and contraction characteristics that correspond to changes in the viscosity of the fluid, the thrust flying height will not change even when the temperature fluctuates, and a constant and stable head position can be maintained at all times. This makes it possible to stabilize recording and playback performance. In the structure of this embodiment, (1) the rotary body is supported in a non-contact manner using fluid dynamic pressure, so vibration and noise on the rotating side and the stationary side during rotation can be significantly reduced. In addition, the wear of the sliding surface can be eliminated, making the bearing part long-lasting. (2) Since all rotating parts are housed in a semi-closed space recessed by the upper and lower drums, this structure has a high masking effect against noise. (3) Since the upper drum is fixed, the air flow pressure against the video tape is extremely small even when the video head rotates, and the tape does not float. Therefore, even under low tape tensile strength, good contact between the tape surface and the head can be maintained at all times, and stable head output performance can be obtained. In addition, (4) the influence of the eccentricity and rotational vibration of the upper drum on the head output can be eliminated;
(5) The input/output video signal processing electronic circuit of the rotating transformer is built into the cylinder or covered with a conductor case, which prevents noise from entering. Also easily converts video signals
/ N can be significantly improved. (6) The influence of the upper drum surface condition on tape running performance can be significantly reduced.

Therefore, the material, surface shape, dimensional accuracy, etc. of the upper drum can be designed with many degrees of freedom. (7) Since it has a fluid holding section, it can stably supply fluid to each group section and ensure lubrication. It also prevents the scattering and leakage of the fluid, prevents deterioration of fluid performance, and extends the service life. easy. This makes it easy to automate the installation process and reduce costs. Furthermore, since there is no need to provide a fixing member on the side of the drum, the entire device can be made smaller and lighter. (9) Since a fluid bearing is used, the outer diameter of the bearing can be made smaller, and the outer diameter of the rotating transformer can be made smaller, making it possible to replace the video head. (10)
Since all the rotating body parts including the motor rotor can be integrated in advance as a semi-assembly, it is easy to assemble the rotating body parts and improve accuracy. Further, there are advantages in that the number of steps for assembling the entire rotary head device is small, and each operation is simple and easy to automate.

FIG. 4 is an fs2 embodiment diagram of the rotary head device of the present invention.
Compared to the first embodiment, a cylindrical rotating transformer is used, the first rotating structure 5 is made of a magnetic material to prevent bad air from leaking from the motor rotor magnet 12, and the shaft 1
A narrow diameter portion is provided in the middle of the herringbone group at 2s, a video signal processing electronic circuit 42 and a substrate 51.
The main difference is that this is provided on the outer circumferential side of the stationary side yoke 8 of the rotary transformer. In particular, in the structure of this embodiment, since a cylindrical rotary transformer is provided, the outer diameter of the transformer can be significantly reduced.

Therefore, the inner diameter of the second rotary structure 4 can be reduced to increase the attachment area to the first rotary structure 3, allowing for high-precision installation. Easy to work with. Therefore, the replaceability of the video head 6 can be further improved. Other effects are described in the above-mentioned 1.
This is the same as in the embodiment.

FIG. 5 is a diagram showing a third embodiment of the present invention, in which the rotating side yoke 7 of the cylindrical rotary transformer is made into an outer cylinder, and this is used as the video head 6.
It is characterized in that it is fixed and integrated with the inner diameter part of the second rotating structure 4, which is fixed thereto. With this structure, the rotation yoke 7 of the rotary transformer and the video rad 6 can be fixed on the common base, so when replacing the video rad 6, there is no need to remove or attach the connection wiring between the rad 6. can. Therefore, serviceability such as head replacement and internal inspection can be improved.

Within the scope of this configuration, the rotary transformer may have a flat shape.

FIG. 6 is a fourth actual IM example of the present invention, which has a structure in which a cylindrical rotary transformer with an outer diameter smaller than the motor rotor is provided on the lower surface of the first rotating structure 3 and inside the motor rotor. be. Video signal processing electronic circuit 4 connected to rotating transformer
2 is installed on a substrate provided on the outer lower surface of the lower drum 11 together with a motor drive circuit 40 and the like, and is covered with a conductor case 70.

With this structure, the second rotating structure 4 to which the video head 6 is fixed can be provided on the top surface of the first rotating structure 3 regardless of the dimensions of the rotating transformer, so the degree of freedom in the mounting structure of the rotating structure 4 can be increased. . Further, since the member for fixing the stationary side yoke 8 of the rotary transformer (for example, the disk 9 in the first to third embodiments) can be eliminated, the number of parts can be reduced and the precision of assembling the upper drum 10 can be improved. Furthermore, since the electronic circuits can be concentrated and installed at the bottom of the device, the structure is small, compact, and easy to handle.

FIG. 7 is another embodiment of the upper drum fixing structure, in which the upper drum 10 is fixed at the upper end of the thin 1 to 41, and the upper drum 10 is fixed to the side surface of the lower drum 11 by a fixing member 90. This part also has a structure in which the upper drum 10 is fixed to the lower drum 11. With this structure, the fixing strength of the upper drum can be increased, and the mounting accuracy and vibration resistance can be improved.

In addition to the structure of the above-described embodiments, within the scope of the present invention, the rotating side yoke 7 of the rotating transformer and the first or second rotating structure may be integrally constructed using a magnetic material such as ferrite, or the motor rotor yoke may be included. An integrated structure is also considered, and these are effective in terms of reducing the number of parts, reducing assembly man-hours, and improving assembly accuracy. Furthermore, the motor may be a cylindrical circumferentially opposed motor or may be other than a brushless motor.

〔Effect of the invention〕

According to the present invention, the rotating head device has a structure in which: (1) the rotating body including the video head is supported in a non-contact manner by a fluid dynamic pressure bearing, and supporting portions are provided at the upper and lower ends of the rotating body; vibration can be significantly reduced.

(2) Since the rotating part is semi-closedly built into the space formed between the upper drum and the lower drum, noise during rotation can be significantly reduced.

(3) Due to the structure in which the upper drum is fixed, disturbances to the videotape can be significantly reduced, resulting in low jitter, low wow, and low flutter.

(4) Since floating of the video tape due to the thin film of flowing air on the side surface of the upper drum can be prevented, good head contact with the tape can be obtained even under a small amount of head protrusion or low tape tension, and stable head output can be obtained. In addition, damage to the tape surface and wear on the head can be improved. Furthermore, since the frictional resistance between the tape and head can be reduced, the electric power of the motor driving the rotating part can be reduced.

(5) Since the video head can be easily replaced, serviceability can be improved. Maintenance and inspection of the video head and other parts becomes easier.

(6) Since the upper drum is fixed to the upper end of the fixed shaft, the upper drum can be mounted with high precision in its posture and the assembly work is easy. Also, since the shaft is fixed, there is no torsional vibration of the shaft.

(7) Since the entire rotating body including the motor rotor can be semi-assembled and integrated in advance, it is easy to improve the accuracy of the rotating body. Furthermore, the number of steps required for assembling the entire rotary head device can be reduced. Furthermore, each task is simple and easy to automate.

(8) Since the bearings are provided at the upper and lower ends of the rotating body, vibrations at the center of the rotating body can be reduced. Therefore, vibrations in the video head mounting portion can be suppressed to a low level.

(9) Since the rotating transformer signal processing electronic circuit is provided close to the rotating transformer and covered with a conductor, the noise of the signal can be reduced and a high S/H can be achieved. Furthermore, the device including the circuit can be made small and compact.

00) Since a fluid dynamic pressure bearing is used, the outer diameter of the bearing can be made small, which allows the rotary transformer to be made smaller and the head replaceability to be improved. Furthermore, since the built-in motor size can be increased, motor efficiency can be improved and power consumption can be reduced, among other effects.

[Brief explanation of drawings]

FIG. 1 is a sectional view of the first embodiment of the rotary head device of the present invention, FIG. 2 is an enlarged view of the journal support in the structure of the same embodiment, FIG. 3 is an enlarged view of the thrust support, and FIG. The figure is a cross-sectional view of the second embodiment of the present invention, FIG.
The figure is a sectional view of another embodiment of the upper drum fixing structure. 1... axis, 2-, . 22... Group, 3... First rotating structure, 4... Second rotating structure, 6... Video head, 20... Thrust receiving structure, 42... Video signal processing electronic circuit , 100...Lubricating fluid, 50.51.52.53...Substrate. Agent Patent Attorney Ko Yu Ming Futan 1 Figure 2 Stems 3 Figures 1000 Figures 5 Figure 4 Chopsticks Figure 1 1O:

Claims (1)

[Claims] 1. In a VTR rotary head device in which a structure to which a video head is fixed is rotationally driven by a motor directly connected to the structure, there is a shaft fixed to the center of at least the lower drum side, and an upper part fixed to the upper end of the shaft. a drum; a first rotating structure that is concentrically separated from the upper drum and that engages the shaft and the thrust receiving section in a non-contact manner via a fluid dynamic pressure bearing section; a second rotary structure fixed concentrically to the outer periphery of the structure and having a video head directly or indirectly fixed to the outermost periphery; a thrust receiving structure; a rotating transformer having an outer diameter smaller than or equal to the inner diameter of the second rotating structure or the inner diameter of a motor rotor; and a drive motor having the motor rotor fixed to the first rotating structure; an electronic circuit for processing input or output signals of the rotary transformer, and the first and second rotary structures, the fluid dynamic pressure bearing section, the rotary transformer, and the drive motor in a space surrounded by at least the upper drum. What is claimed is: 1. A rotary head device characterized by a structure in which a rotary transformer signal processing electronic circuit is located close to a fixed yoke side of the rotary transformer and is provided in a space surrounded by a conductor such as a drum.