JPS59142727A - Cylinder unit for vtr head - Google Patents

Abstract

PURPOSE:To reduce a VTR head and a cylinder unit in size and power consumption greatly by using a motor which has radially magnetized rare earth magnets formed by compression or injection molding, and sandwiching the motor between an upper and a lower cylinder. CONSTITUTION:The upper cylinder 22 is fixed on a rotating shaft 1 and a fixing jig 23 for the rotating shaft is engaged threadably. A motor yoke 24 is arranged at the inside of the upper cylinder 22 and a rotor magnet 25 is fitted at the inside of the motor yoke 24. A magnetic head 26 is engaged threadably to the upper cylinder by being adhered to a head base 27. For signal transmission from the head, a lower rotary transformer is fixed to the upper part of the upper cylinder and the coil of this rotary transformer and the coil of the magnetic head are connected to rotate them in one body. The other side of the rotary transformer is connected by an upper rotary transformer 29 from its coil to an electric circuit for recording and reproduction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a head and cylinder unit that is the main device of a VTR, and to a head and cylinder unit for making the VTR ultra-compact and reducing power consumption.

An example of a cross-sectional view of a conventional VTR head' and cylinder unit is shown in FIG. To explain this structure, the rotating shaft 1
The VC has an upper cylinder 2 and a motor yoke fixing jig 3 fixed to it. An outer motor yoke 4 and an inner motor yoke 5 are attached to the motor yoke fixing jig 6, and a four-ter magnet 6 is fixed to the outer motor yoke.

A motor active coil 7 is arranged in the gap between the rotor magnet and the inner motor yoke, and by passing a driving current through the coil 7, torque and torque are generated in the rotor magnet 6, and in this figure, the magnet rotates. . Therefore, it is a brushless motor that directly drives the cylinder. Lower cylinder 9 fixed to chassis 8
A ball bearing 10.11 is arranged to rotate the rotating shaft 1. Motor drive coil 7
The coil is fixed to the lower side of the chassis of the lower cylinder 9.
12 is fixed, and the upper cylinder 2, which is integrated with the lower cylinder, is equipped with a video head 13 (in the case of FM audio, and in the case of PC!M audio, audio can be recorded and played back by the image head). (of course) is glued to the head stand 14, and the head stand is attached with screws. Note that two magnetic heads are usually attached at 180 degrees. The coil terminal of the magnetic head is connected to one side 15 of the rotary transformer,
One side 15 of the rotary transformer rotates integrally with the upper cylinder. Other side of rotary transformer 1
6 is fixed to the lower cylinder, and from this coil the head,
It is connected to the electric power circuit outside the cylinder unit. The magnetic tape, which is a recording medium, moves obliquely through the gap between the upper and lower cylinders, following the tape guide 17 in the lower cylinder.The magnetic head contacts the tape to perform recording and playback.This kind of conventional VTR head and cylinder unit has the following drawbacks:

■Since the motor rotor magnet coverlume 7 for rotating the head is also made of light and strontium ferrite, the magnetic energy is 2"4M at B Hmax.
GOe, the magnet size increases, the height of the cylinder increases, and the overall thickness of the VTR increases.

■As mentioned above, the energy product of the rotor magnet is 2 to 4M.
Since it is GOe, the motor efficiency is low and the power consumption -φ (large).Therefore, it is not suitable for ultra-small portable VTRs such as future 8 mm video cameras.

The present invention eliminates all such drawbacks, and its purpose is to miniaturize the VTR head and cylinder unit. Another object of the present invention is to reduce the power consumption of a VTR head and cylinder unit. Still another object of the present invention is to provide a full-fledged portable VTR for 8 mm video and the like by achieving the above object and reducing the weight of the VTR.

The present invention will be described in detail below based on Examples.

FIG. 2 is a sectional view of one embodiment of the present invention. Rotating shaft 21
The upper cylinder 22 is fixed to the rotating shaft fixing jig 23.
is screwed on. A motor yoke 24 is fixed to the inside of the upper cylinder 22, and a rotor magnet 25 is attached to the inside of the motor yoke 24. The motor yoke 24 constitutes the magnetic circuit of the motor, and is intended to provide a shielding effect against magnetic noise, electrical noise, etc. generated by the motor 5. Furthermore, a magnetic head 26 is bonded to a head stand 27 and screwed to the upper cylinder. The signal transmission from the head to the head is carried out by a rotary transformer, which is fixed at the top of the upper cylinder, and the coil of this rotary transformer is connected to the coil of the magnetic head so that they can rotate as a unit. The other side of the transformer is the upper rotary transformer 29,
This coil is connected to the recording and playback electrical circuits.

The lower cylinder 30 has a ball bearing housing 61
and is fixed to the chassis 62.

Ball bearings 33 and 34 are attached to the housing 31 and are set at t and I so that the rotating shaft 21 can rotate. The housing 61 has a motor skirter.
35 has been installed and the motor coil 36 has been wound. When a motor drive current is passed through the motor coil 36, torque is generated in the rotor magnet integrated with the upper cylinder 22, causing it to rotate. 37 is a tape guide. The drive current is a brushless motor supplied from a drive circuit outside the cylinder.

It is also a direct-write motor in which the magnetic head is directly rotated by the motor. The tape guide 67 is obliquely attached to the lower cylinder, and the tape moves according to this tape guide, and the image head 26 scans at an angle to the longitudinal direction of the tape, resulting in a so-called helical scan method.

The feature of the present invention lies in the rotor magnet of the head and cylinder unit. This magnet is a rare earth magnet, and in terms of manufacturing rare earth magnets, it is classified as follows. ■Sintered magnets made by blending rare earth elements such as samarium and cobalt in a specific atomic ratio, melting and heat-treating them under appropriate conditions, and then crushing and sintering.■Crushing the above-mentioned crushed magnetic powder and adhering it appropriately. It is broadly categorized into resin-bonded magnets that are bonded with resin.

Although the rotary magnet of the present invention can be applied to either type 1 or type 2, preferably resin bonded magnet type 4 is more suitable. The reason for this is that even if the radial thickness of the magnet is set to 0.5 - 2.0 mm, no deformation, cracks, etc. occur, and the magnet can be used as a rotor magnet without modification. In other words, the productivity is extremely good, and as a result, the cost is also reasonable. ■Resin-bonded rare earth magnets can be classified into ■compression-molded magnets, which are manufactured by kneading resin and magnetic powder and hardening with compression heat, and ■injection-molded magnets, which are manufactured by kneading resin and magnetic powder and then injection molding. It will be done.

When the above magnets that can be manufactured at present are arranged in order of the magnitude of the magnetic product:'7 energy product, the results are as follows. Sintering mold: 30MGOe, compression molding mold: 17MGOe, injection molding mold: 8MGOe. By the way, even though the barium ferrite magnet and the strontium 7 elite magnet are anisotropic high-performance magnets, they have a power of 2 to 4 MGOe, so even injection molded magnets with the lowest energy product among rare earth magnets have the same performance on the can plate. There is. For this purpose rare earth magnets are used in motors.

- It is possible to reduce the volume of the ferrite magnet by half or less by using it. When applying a rare earth magnet to a VTR, rad, or cylinder unit, use a radial gear knob type, magnetize 7 magnets with multiple inner diameter poles, set the gap between the magnet and stator to 02-03, and increase the radial thickness of the magnet. If it is 05 to 2 m@, the permeance coefficient will be 3 to 6, and the magnetic flux can be used effectively even if the magnet volume is reduced (cost reduction).

Next, we will discuss magnetization.

Figure 3 is a diagram showing the state of magnetization of the rotor magnet used in the head and cylinder unit. FIG. 3B shows an example of the rare earth magnet of the present invention, which is molded into a radially anisotropic magnet by compression molding or d-injection molding, and then multipolar radially magnetized.

Figure 6 A and B both have 6 magnetic poles and the same inner diameter.
In Figure A, ferrite magnets 41 are inserted and glued inside the rotor yoke 4°. As shown in the figure, the magnetic field lines for magnetization pass through the inside of the magnet 41 from the S pole to the N pole, so the magnet utilization rate decreases and the magnetic flux cannot be used effectively.On the other hand, in Bll, rare earth The magnet 43 is inserted into the rotor yoke 42 and glued to it, but the lines of magnetic force enter the rotor yoke from the south pole, pass through the rotor yoke and enter the north pole, and at the same time the lines of magnetic force are completely oriented in the radial direction, so the magnetic flux A major feature is that it can be used 100%. Also, as can be seen from the figure, although the radial thickness of the magnet is thinner, the magnetic flux density is more than twice that of the conventional one. In this way, by forming a rare earth magnet to have radial anisotropy and radially magnetizing it, the magnetic performance is increased despite the small size of the magnet.

This radial magnet is manufactured by compression molding or injection molding, but if mass production is taken into account, it is effective to use injection molded magnets.

Figure 4 shows the B-HFM of a 7-engine light magnet and a rare earth magnet.
It is a figure showing I line. The vertical axis represents the residual magnetic flux density B, and the horizontal axis represents the coercive force H. 44.45 is the color gamut of ferrite magnets, and 46, 47, and 48 are rare earth magnets, which are injection molded, compression molded, and sintered magnets, respectively. 11 each. For the curve, set the value of B: Hmax to 2°4.8, 17.30
It is indicated by MGOe-. Permeance coefficients 3 to 6 for the motor are shown as straight lines from the origin. As can be seen from Figure 4, with ferrite, the usable magnetic flux density is around 3000 Gauss, while with rare earth magnets, even injection molded magnets have a magnetic flux density of around 4500 Gauss, which is about double that. It will be done. 650 for compression molded magnets
The magnetic flux density becomes around 0 Gauss, and an extremely high magnetic flux density can be obtained. Although sintered magnets have high performance, if they are made into thin-walled magnets, deformation, cracks, cracks, etc. occur as described above, and it is difficult to use them in this form practically.

As described above, the VTR head/cylinder unit of the present invention uses compression-molded rare earth magnets or radially magnetized injection-molded magnets for the motor.
The magnetic flux density is on the can plate of the ferrite magnet, and accordingly, the motor efficiency is on the can plate, so the motor efficiency is also on the can plate.

Therefore, power consumption is reduced to less than half, making it possible to significantly save energy. Furthermore, since this motor is placed in a sandwich-like arrangement inside the upper and lower cylinders, the magnet volume is small and the height is also reduced, resulting in an extremely thin cylinder unit. As described above, according to the present invention, it is possible to make the VTR head and cylinder unit extremely compact and have low power consumption. Not only is it optimal for millimeter VTRs, but it can also be applied to even smaller VTRs. In addition, the current beta type VTR, V
If used in an HS type VTR, it can be made smaller and lighter, and the effect is significant.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a conventional VTR head and cylinder unit, FIG. 2 is an example of a sectional view of the VTR head and cylinder unit of the present invention, and FIG. 3 is a diagram showing the state of magnetization of the rotor magnet. Figure A is a diagram showing the case of conventional ferrite, Figure B is a diagram showing the case of the rare earth magnet of the present invention, and Figure 4 is a diagram showing the B-H curve of the ferrite magnet and the rare earth magnet. 1...Rotating shaft 2...Upper cylinder 6...
・Rotor magnet 7...Motor drive coil 9...
・Lower cylinder 10, 11...Ball bearing 13...Magnetic head 14...Head stand 15.1
/+...Rotary transformer 21...Rotating shaft
22... Upper cylinder 24... Rotor yoke/shield plate 25... Rotor magnet 26... Magnetic head 27... Head stand 28. 29... Rotary transformer 60... Lower cylinder 31 ...Bearing housing 33.34...Ball bearing 35...Stator 66...Motor filter 4
0.42...Rotor yoke 41...Ferrite magnet 46...Rare earth magnet 44.45...Ferrite magnet 46...Rare earth injection molded magnet 47...Rare earth compression molded magnet 48...Rare earth sintered Each shows a condensed magnet. Applicant: Suwa Seikosha Co., Ltd. Figure 1 Figure 2

Claims (1)

[Claims] 1) Upper cylinder, lower cylinder equipped with a tape guide
A helical scan type VTR cylinder unit comprising a rotating video magnetic head, a direct drive for rotating the magnetic head, and a brushless motor, wherein the rotor magnet of the motor is a rare earth magnet. . 2) The cylinder unit for a 'VTR head as set forth in claim 1, wherein the rotor magnet of the motor that rotates the image magnetic head is a resin-bonded rare earth magnet. 3) A VTR head and cylinder unit, wherein the resin-bonded rare earth magnet according to claim 2 is magnetized in a radial direction. 4) A VTR according to claims 2 and 3, in which the motor for rotating the video magnetic head is disposed in a sandwich shape within the upper and lower cylinders, and the rotor magnet is a magnet.
Cylinder unit for head.