JPH04366405A - rotating erase head - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary erasing head for erasing signals recorded on a magnetic recording medium using alternating current, and more particularly to a rotary erasing head capable of improving erasing efficiency with low current drive.

0002

2. Description of the Related Art In an erasing head with improved erasing characteristics, as described in Japanese Patent Laid-Open No. 60-89805, a signal to be erased is transferred to a magnetic tape again using an erasing frequency component as a bias. In order to prevent the re-recording phenomenon where data is recorded on top of the core, the shape of the core piece is processed so that the magnetic field intensity distribution generated from the magnetic gap draws a gentle slope on the recording medium escape side relative to the gap formation position. It has been known.

0003

[Problems to be Solved by the Invention] The prior art disclosed in the above-mentioned prior application was developed by considering the magnetic field strength distribution generated from the magnetic gap, but no consideration was given to improving the erasing rate of the erasing head. It wasn't. For this reason, conventional rotary erasing heads often leave minute low-frequency signals on the deep side of the tape unerased.
Tapes with high residual magnetic flux density Br, such as tapes and metal tapes, and video quality improved accordingly, such as commercial VTRs.
etc., unerased minute low-frequency signals may appear in the image quality, causing a deterioration in image accuracy. Also, if you increase the erase current to compensate for this,
The erase current flows into the image head, causing beat disturbance. Furthermore, if we try to improve the erasing rate by increasing the number of erasing heads, simply increasing the number of erasing heads will lead to an increase in the transformer coils of the rotating transformer to supply current to the erasing heads. This will reduce the Therefore, the technical problem to be solved by the present invention is to solve the above-mentioned problems of the prior art, and its purpose is to provide a rotary erasing head that can improve erasing efficiency while being driven with a low current. There is a particular thing.

0004

[Means for Solving the Problems] In order to achieve the above object, the present invention provides at least two or more erasing magnetic head cores that are arranged close to each other so as to trace on the same trajectory on a head support for an erasing magnetic head. The erasing magnetic head core erases one field or one frame on the magnetic recording medium at least twice, and erases data per winding of the erasing magnetic head core. The current is reduced to 1/2 or less of the conventional one. Also,
The circuit configuration of the windings wound around each of the erasing magnetic head cores is arranged in parallel, and only one transformer coil for the erasing head mounted in the coil groove of the rotary transformer is assigned to each head support.

[0005]

[Effect] The erasing curve of the erasing characteristic has the largest erasing rate gradient at low current, and by performing erasing in this characteristic region two or more times in close proximity, it is possible to erase Even with an erase current that is 1/2 or less of the set current, it is possible to obtain an erase rate that is equal to or higher than the conventional one. Furthermore, since the erase current is small, there is no current beat disturbance caused by the difference in the carrier frequency of the rotating erase head and the video carrier frequency.

[0006]

[Embodiments] Hereinafter, embodiments of the present invention will be explained with reference to FIGS. 1 to 6. FIG. 1 is a plan view showing the external appearance of a rotary erasing head according to an embodiment of the present invention, and FIG. 2 is an enlarged view of a main part of the head sliding surface in FIG. In FIG. 1, reference numeral 1 denotes a head support body mounted on a rotating cylinder (not shown), and erasing magnetic head cores 2A and 2B are fixed onto paired protrusions 1a and 1a of the head support body 1, respectively. Yes, this 2
Working gap 3A of two erasing magnetic head cores 2A, 2B
, 3B are arranged close to each other so that they trace the same trajectory as shown in FIG. Further, each erasing magnetic head core 2A, 2B is provided with excitation windings 4A, 4B, and after each winding 4A, 4B is wound around the magnetic core, the corresponding terminals are brought together to form the head. They are soldered to connection patterns 5a, 5a of relay board 5 of support body 1, and as shown in FIG. 3, both windings 4A, 4B are electrically connected in parallel.

FIG. 3 is an explanatory diagram showing the relationship between the rotary erasing head and the transformer coil of the rotary transformer for signal transmission. In the figure, 6 is a rotating transformer, 7 is an erasing head transformer coil on the rotating transformer rotor side, and 8 is an erasing head transformer coil on the rotating transformer stator side. As is clear from the figure, the two
In other words, one transformer coil 7 on the rotating transformer rotor side is connected to one winding 4A, 4B, or in other words, one transformer coil 7 on the rotary transformer rotor side. By doing so, only one groove for mounting the erasing head transformer coil formed on the rotor and stator side of the rotary transformer 5 is required for each head support 1, and other models are not required. - The configuration is such that the space factor of the groove for installing the transformer coil, that is, the transmission efficiency, is not reduced. In addition, in FIG. 3, 9 indicates a magnetic tape.

FIGS. 4 and 5 are explanatory diagrams conceptually showing an erasing method on a magnetic tape. In FIG. 4, the track width of the working gaps 3A and 3B of the erasing magnetic head cores 2A and 2B is formed to be one field track width, so that the signal for one field is erased twice for each field. An example is shown below. In this case, two rotary erasing head assemblies shown in FIG. 1, each comprising a pair of erasing magnetic head cores 2A and 2B fixed to the head support 1, are mounted 180 degrees opposite each other on a rotating cylinder (not shown). Ru. FIG. 5 shows working gaps 3A, 3 of the erase magnetic head cores 2A, 2B.
The track width of B is formed to be 2 field track width,
An example is shown in which the signal for one frame is erased twice for each frame. In this case, only one rotary erasing head assembly shown in FIG. 1 described above is mounted on a rotary cylinder (not shown). In both cases of FIGS. 4 and 5, the current flowing through each winding (4A, 4B) of each erasing magnetic head core is set to 1/2 or less of the stable region current of the erasing characteristic. .

As described above, it goes without saying that the erasing rate increases by multiple erasing one field or one frame, but if the erasing magnetic head cores are configured independently as in the present invention, there is no interference between the cores. The efficiency of magnetic field generation is also improved. Furthermore, since the core windings are connected in parallel, even if the number of erasing magnetic head cores is increased, the number of grooves in the rotary transformer will not be increased. In other words, a rotary transformer has predetermined transmission grooves set on a constant cross-sectional area, but in a rotary transformer whose performance is controlled by the cross-sectional area, an increase in the number of grooves directly means a deterioration of the rotary transformer's performance. The effect of the present invention is significant in this case.

On the other hand, the conventional rotary erasing head was used by passing a large current of about 150 mA through the magnetic core, as shown by the erasing characteristic curve a shown in FIG. This is because unless the erasure rate is 30 dB or more, the low frequency signal cannot be completely erased and appears on the playback screen. However, this 150
Because of the large current of mA, current beat disturbances caused by the difference between the carrier frequency of the rotating erasing head and the video carrier frequency may occur on the screen. For example, when the carrier frequency of the rotating erase head is 12 MHz, S-V
In the case of HS, beats occur in the chroma signal band (approximately 1 MHz). Therefore, in order to increase the erasure rate, by using a material for the magnetic core with a high saturation magnetic flux density, or by providing a large number of gaps in the magnetic core, and by passing a larger current, the erase characteristic curve will be as shown in curve b. Although the erasing rate increases, the problem of beat interference becomes noticeable. In contrast, in the present invention, as described above, the current flowing through each winding (4A, 4B) of each erasing magnetic head core is set to 1/2 or less of the stable region current of the erasing characteristic, and multiple erasing is performed. Therefore, the erasure rate can be improved at low current.
Its erasing characteristic is as shown by the erasing characteristic curve c, and an erasing rate equal to or higher than the conventional one can be obtained with less than 1/2 of the conventional current.

[0011]

[Effects of the Invention] As described above, according to the present invention, since multiple erasing is performed at least twice with low current,
Even with an erase current that is less than 1/2 of the set current used in conventional rotary erase heads, it is possible to obtain an erase rate equal to or higher than that of the conventional rotary erase head. Further, since sufficient erasing can be performed with a low current, there is no leakage of signals to other modes, and even if the number of heads is increased, the number of rotary transformer grooves does not increase. Overall, a rotary erasing head compatible with high-quality VTRs can be provided, and its value is great.

[Brief explanation of drawings]

FIG. 1 is a plan view showing the appearance of a rotary erasing head according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a main part of the head sliding surface in FIG. 1;

FIG. 3 is an explanatory diagram showing the relationship between the winding of the rotary erasing head and the transformer coil of the rotary transformer.

FIG. 4 is an explanatory diagram conceptually showing an example of a one-field double erasing method on a magnetic tape.

[Figure 5] One frame double erasing method on magnetic tape
It is an explanatory diagram showing an example conceptually.

FIG. 6 is an explanatory diagram showing an erasing characteristic curve.

[Explanation of symbols]

1 Head supports 2A, 2B Erasing magnetic head cores 3A, 3B Operating gaps 4A, 4B Winding 5 Head support relay board 6 Rotating transformer 7 Rotating transformer transformer coil 8 for erasing head on rotor side Rotating transformer for erasing head on stator side Transformer coil 9 Magnetic tape

Claims (3)

[Claims] 1. At least two or more erasing magnetic head cores are disposed close to each other so as to trace on the same trajectory on a head support for an erasing magnetic head, and each erasing magnetic head core is used to erase data on a magnetic recording medium. A rotary erasing head characterized in that erasing is performed at least twice for one field or one frame. 2. According to claim 1, the circuit configuration of the windings wound around each of the erasing magnetic head cores is parallel, and one transformer coil for the erasing head is mounted in a coil groove of a rotary transformer for each of the head supports. A rotating erasing head characterized by: 3. The rotary erasing head according to claim 1, wherein a current flowing through each winding of each erasing magnetic head core is set to 1/2 or less of a stable region current of erasing characteristics.