RU1797723C - Video tape recorder rotating magnetic head assembly - Google Patents

Abstract

Usage: in the technique of magnetic video recording for playing back phonograms under adverse interference conditions, as well as for diagnosing the recording channel of a VCR in real time. The inventive optical source and receiver, a polarizer, an analyzer and single-mode optical fibers that do not distort the polarization, the number of which corresponds to the number of video heads and which are covered by a magnetic circuit or head windings on a rotating drum and placed under a contactless current collector, are inserted into the unit, the rotor of the engine and the electron-optical sensor of its angular position along the axis of rotation of the motor shaft, one ends of which go to the end of the shaft and are optically coupled to the motionless E polarizer and the radiation source, and the other to the opposite end of the shaft and aligned with the housing fixed to the analyzer and a radiation receiver connected to the pre-amplifier and shaper of reproduced video signals. 3 ill. . fe

Description

The invention relates to a technique for magnetic video recording and can be used to play videophonograms in two-head VCRs with a horizontal angle of recording with a drum angle of 180 ° and four-head horizontal and horizontal records with a angle of 90 ° in an unfavorable environment, as well as for diagnosing a channel VCR recordings in real time.

Known blocks of rotating magnetic heads (BHG) for oblique line and transverse line recording, containing

a stationary guide drum with a housing; a drum with rotating heads connected to a rotor of a contactless collector inductively coupled to stator windings connected to a recording or reproducing pre-amplifier. A rotary head drum and non-contact current collector rotor rings are mounted on a motor shaft, which rotates in precision bearings, and whose rotor windings are switched by means of a manifold, and in non-contact moment motors, stator windings from

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a rotor position sensor of the engine, which is a source of interference that impedes the reproduction process.

Close to the technical nature and purpose of the proposed invention is BVG, in which to reduce the level of interference and interference, the amplifier is mounted on a rotating drum, while the magnetic heads are galvanically connected to the amplifiers, and the latter with a contactless current collector. Such a technical solution complicates the design of the rotating drum and does not eliminate the influence of interference from external electromagnetic radiation on the reproduced signals; moreover, it requires additional transmission of voltage from the amplifiers through the contactless current collector to the rotating drum. This complicates the design of the non-contact current collector BVG and fundamentally does not allow monitoring the recording channel of the VCR during recording,

The aim of the invention is to eliminate the influence of external electromagnetic radiation on the signals reproduced by the video heads, as well as to control the recording mode in real time.

This goal is achieved by the fact that a source and a receiver of optical radiation, a polarizer, an analyzer, and optical single-mode fibers that do not distort polarization, the number of which corresponds to the number of video heads and which are covered by a magnetic circuit or windings of heads on a rotating drum, are placed under contactless the current collector, the rotor of the engine and the electron-optical sensor of its angular position along the axis of rotation of the motor shaft, one ends of which are on the shaft end and are optically coupled to the motionless placed by the polarizer and the radiation source, and the others on the opposite end of the shaft and are matched with the radiation analyzer and the receiver connected to the preamplifier and the reproducer of reproduced video signals fixed on the housing.

Figure 1 shows a general view of a block of rotating magnetic heads; Figures 2 and 3 are examples of the construction of video heads with single-mode optical fibers and electric windings.

BVG contains a composite housing with a cylindrical drum 1, on the surface of which a screw guide 2 protruding on the surface perpendicular to the axis of rotation of the BVG is made

a few tenths of a millimeter beyond the surface in contact with the magnetic tape. Precision bearings in which the shaft is mounted are housed in the housing

rotor 5 of a contactless torque motor 6, on one end of which a rotary position sensor 7 is mounted, made in the form of a raster interface of a rotating 8 and a fixed 9 QDisk. Between the bearings, a rotor ring 10 of a ferrite contactless current collector 11 with concentric grooves is installed next to the bearings and windings connected to

5 to the windings of the video heads 12. It is inductively connected through gaps to the stator fixed rings 13 installed in the housing 1 and connected to the output of the recording amplifier or to the input of the preliminary amplifier (not shown). A rotary drum, 1.4 with video heads 12, is mounted on the other end of the shaft. Optical single-mode optical fibers 15 are introduced into the video head, which do not distort polarization 5, with a diameter of 10 microns. The fibers are twisted into a ring, the video heads are fixed on the core and covered with windings (see Fig. 2). To improve playback performance, they can be coated in

0 this place with a magnet layer of soft material. Another embodiment is shown in FIG. Z. Fibers coated with a layer of soft magnetic material are placed in an additional clearance of the video head 12, Ends

5 fibers from each video head are laid and grooves 16 on the motor shaft together with the conclusions of the windings of the video heads and output to the ends of the shaft along the axis of rotation, where the polarizer 17 and analyzer 18 are installed, interacting along with the radiation source 19. (LEDs, laser diode) mounted on an electrostatic charge remover 20, mechanically in contact with the end surface

5 of the shaft, and a radiation receiver 21 (pin diode, avalanche photodiode), fixedly mounted on the housing 1 and connected to a pre-amplifier and a shaper of the playback video signal (not shown). For normal operation of the second-harmonic generation, it is necessary that the fiber area on the axis of rotation The shaft fits into the sensitive area of the radiation receiver.

5 BVG works as follows. When the recording current is supplied from the recording amplifiers through the stator windings of the contactless current collector 11, s of the rotor windings 10, the voltage applied to the windings of the video heads 12 is induced.

the current that creates the magnetic field of the record in the magnetic circuit along the fiber (Fig.2) and across (Fig.Z). The rotation of the video heads and windings of the contactless torque motor 6 is carried out by a signal from the position sensor of the rotor of the motor 7. From the radiation source 19, the radiation mode enters the polarizer 17 defining the initial plane of polarization, and then passes through the fiber 15 to the analyzer 18 and radiation receiver 21. In the absence of current in the windings of the video heads, the polarizer and analyzer are set to the crossed position, and the total signal perceived by the receiver is zero. When interacting with a magnetic field, the radiation mode experiences a rotation of the plane of polarization due to the Farade effect (Fig. 2) and the Kerr effect (Fig. 3).

Passing through the analyzer 18, it enters the radiation receiver 21, the output signal from which is proportional to the recording current. When playing video phonograms with video heads, the magnetic flux of the phonogram penetrates the magnetic circuit of the video head in contact with the magnetic tape and acts on

an optical fiber through which a radiation mode passes from the radiation source 19 to the receiver 21 with the given polarizer 17 being the spatial position of the plane of polarization, which rotates under the influence of magneto-optical effects. The analyzer 18 passes the component of the radiation mode, and the receiver 21 senses a signal proportional to the magnetization of the magnetic tape and feeds it to a preamplifier and a video driver (not shown).

The use of optical fibers in BHG when playing video phonograms due to their non-induction ™, i.e. there is practically no influence of electromagnetic induction, and hence the negative phenomena associated with electrical discharges, proximity to electrical sources

and magnetic fields, current pulses in the supply network, etc. on the reproduction process, allows for small reproduction signals to reduce the effects of interference, i.e. to improve the quality of reproduction, and due to the high information throughput of the optical fibers to have a broadband reproduction channel. -.

Claims (1)

The claims A block of rotating magnetic heads of a VCR, comprising a housing with a guiding drum and a non-contact motor, on the shaft of which an electron-optical sensor of its angular position is mounted on one side of the motor rotor and on the other a rotor ring inductively coupled to the stationary stator rings of the contactless current collector, and a rotating drum with video heads that are connected to the windings of the rotor rings, characterized in that, in order to eliminate external electromagnetic radiation on reproducible signals, as well as monitoring the recording channel of the VCR during the recording process, an optical radiation source and receiver, a polarizer, an analyzer and optical single-mode fibers are introduced into it, the number of which corresponds to the number of video heads and which are covered by a magnetic circuit or head windings on a rotating drum and laid under a non-contact the current collector, the rotor of the engine and the electron-optical sensor of its angular position along the axis of rotation of the motor shaft, one ends of which go to the shaft end and are optically coupled to The polarizer and the radiation source are movably located, and the others are located on the opposite end of the shaft and are aligned with the radiation analyzer and receiver attached to the housing and connected to the input preamplifier and the reproducer of reproduced signals connected in series with each other. FIG. 2 Fie.Z