JPH04328301A - Eraser for vtr - Google Patents

Abstract

PURPOSE:To improve the quality of a reproducing picture by making the perfectly erased state of a video tape. CONSTITUTION:A cross talk component from a rotary coil 22-1 is trapped by a trap filter 30 connected between a rotary coil 22-2 and a flying erase head 14.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an erase device for a VTR (video tape recorder).

0002

2. Description of the Related Art In a VTR, a head drum 2 is composed of a rotary drum 4 and a stator drum 6, as shown in FIG.
Various heads such as video heads (for standard mode and 3x mode) 10, high-fidelity (Hi-Fi) audio head 12, and flying erase head 14,
In addition, the balancers 16 are arranged in the required correspondence relationship as shown in FIG. Figure 4
A video head 10 records a video signal as a wide video track VT on the surface thereof, and a high-fidelity audio head 12 records a video tape 1 from the video track VT traced by the video head 10.
Narrow high-fidelity audio track AT in the deep part of 8
While recording the high-fidelity audio signal, the old recording part is erased during recording, but in order to create a beautiful splice recording, the flying erase head 14 is used to combine the old recorded video signal and the high-fidelity audio signal. There is a device that erases with the track width ET.

[0003] A V having each head and its surroundings as described above
In the TR, as shown in Fig. 2, the rotary drum 4
Rotary coil 2 of rotary transformer 20 on the bottom surface of
2 (corresponding to the symbols 22-1, 22-2, etc. in FIG. 5) is a rotary coil 22 on the upper surface of the stator drum 6.
(Although not shown in Fig. 2, the numbers correspond to 24-1, 24-2, etc. in Fig. 5) so as to face the stator coils.
As shown in FIG. 5 in detail, the rotary transformer 20 includes a rotary coil 22-1 connected to the high-fidelity audio head 12 and a stator coil 24-1 connected to the high-fidelity audio amplifier 26. It further includes a rotary coil 22-2 connected to the flying erase head 14, and a stator coil 24-2 connected to an oscillation circuit 28 for supplying erase current. In this case, the rotary coil connected to the video head 10 and the stator coil connected to the video signal amplifier are not shown in FIG. 5.

The high-fidelity audio signal amplified by the high-fidelity audio amplifier 26 is transmitted to the stator coil 24-1 of the rotary transformer 20 and the rotary coil 22.
-1 to the high-fidelity audio head 12 and recorded on the video tape 18.

Next, in the recording, the oscillation circuit 2
8, an erase current is supplied to the flying erase head 14 via the stator coil 24-2 and rotary coil 22-2 of the rotary transformer 20, thereby erasing the old recorded video signal and high-fidelity audio signal. .

[0006]

[Problems to be Solved by the Invention] By the way, as the head drum 2 becomes smaller and the number of heads mounted increases, the dimensions between the coils of the rotary transformer 20 become smaller. The high-fidelity audio signal appearing at 22-1 appears as a crosstalk component at the adjacent rotary coil 22-2 side of the flying erase head 14 side.

[0007] If there was such a crosstalk,
When an erase operation is performed by supplying the erase current from the oscillation circuit 28 to the flying erase head 14, the crosstalk component is superimposed on the erase current.
The erased state of the videotape 18, which should have had the old recorded portion completely erased, is disturbed by crosstalk components, which remain as noise.
If you record a video signal on a track in that state,
There is a problem in that the low frequency range of the video signal is adversely affected, and the reproduced image is extremely deteriorated.

Therefore, in the present invention, a trap filter for removing crosstalk components is provided between the flying erase head and the rotary coil of the rotary transformer connected thereto, thereby eliminating the erased state on the videotape. The purpose is to make it possible to completely perform the process, thereby improving the quality of the reproduced image.

[0009]

[Means for Solving the Problems] In order to achieve such an object, the present invention includes a rotary transformer,
The rotary transformer has a flying erase head and a trap filter, and the rotary transformer includes a coil pair consisting of a stator coil and a rotary coil to which erase current is supplied, and a coil pair consisting of an adjacent stator coil and rotary coil. The flying erase head is connected to a rotary coil for supplying erase current, and the erase current is supplied via the stator coil and rotary coil for supplying erase current. , the trap filter is connected between the erase current supplying rotary coil and the flying erase head, and traps crosstalk components from the rotary coils of the adjacent coil pair. .

0010

[Operation] Crosstalk components from the rotary coils of adjacent coil pairs are trapped by the trap filter, so the flying erase head completely erases the signal recorded on the videotape with the erase current supplied to it. be able to.

[0011]

Embodiments Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of the main parts of an erase device according to an embodiment of the present invention. Parts corresponding to those in FIG. .

The VTR in this embodiment is shown in FIGS. 2 and 3.
It has basically the same configuration as the conventional example. A feature of this embodiment is that it includes a trap filter 30 in addition to the basic configuration. Since the basic configuration has been explained as described above, the explanation will be omitted here.

The trap filter 30 is connected between the erase current supply rotary coil 22-2 and the flying erase head 14, and is connected to the high-fidelity audio head side which is a coil adjacent to the rotary coil 22-2. It is designed to trap crosstalk components from the rotary coil 22-1.

This trap filter 30 includes a coil 32
and a capacitor 34, and its trap performance is set to a trap filter value that does not have much of an adverse effect on the erase current. Specifically, the S/N ratio of the erase current is 9:1 when a crosstalk component is superimposed, and when improving this to 9.9:0.1 or less, high-fidelity audio When the carrier frequency of the signal is 1.3 MHz, the inductance value of the coil 32 is 9.9 μH, and the capacitance value of the capacitor 34 is 1500 pF, and the trap filter 30 resonates at that 1.3 MHz, thereby trapping the crosstalk component. be done.

Note that this trap filter 30 is shown in FIG.
By providing it at point A on the circuit board 36 or at the balancer 16, it is possible to eliminate the deterioration of the S/N ratio of the high-fidelity audio signal and the influence of noise on the video signal.

[0016]

[Effect of the invention] As is clear from the above explanation,
According to the present invention, a trap filter for removing crosstalk components is provided between the flying erase head and the rotary coil of the rotary transformer, and this trap filter makes it possible to completely erase the videotape. This made it possible to improve the quality of reproduced images.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of main parts of an erase device according to an embodiment of the present invention.

FIG. 2 is a schematic cross-sectional view of a head drum of a VTR.

FIG. 3 is a diagram showing the mounting arrangement of various heads on a head drum of a VTR.

FIG. 4 is a plan view of a videotape showing the various tracks;

FIG. 5 is a configuration diagram of main parts of a conventional erase device.

[Explanation of symbols]

2 Head drum 4 Rotary drum 6 Stator drum 10 Video head 12 Hi-Fi audio head 14 Flying erase head 16 Balancer 18 Video tape 20 Rotary transformer 22-1, 22-2 Rotary coil 24-1, 2
4-2 Stator coil 30 Trap filter

Claims (1)

[Claims] Claim 1: A rotary transformer (20), a flying erase head (14), and a trap filter (
The rotary transformer (20) has a stator coil (24-2) to which the erase current is supplied.
) and a rotary coil (22-2), and an adjacent coil pair consisting of a stator coil (24-1) and a rotary coil (22-1). (14) is connected to the rotary coil (22-2) for supplying erase current, and erases via the stator coil (24-2) for supplying erase current and the rotary coil (22-2). The trap filter (30) is connected between the erase current supply rotary coil (22-2) and the flying erase head (14), and the trap filter (30) is connected between the adjacent coil pair. A VTR erase device characterized in that it traps crosstalk components from a rotary coil (22-1).