1. Field of the Invention
The present invention relates generally to magnetic head devices, and more particularly, to a magnetic head device that is attached to a rotary cylinder and helically scans magnetic tape in electronic equipment such as a video tape recorder.
In recent years, there has been an increasing demand for high-performance helical scan magnetic head devices, as a larger amount of digital image and audio data are expected to be recorded on magnetic tape at high density for high-quality reproduction.
2. Description of the Related Art
FIG. 1 is a perspective view of a conventional helical scan magnetic head device. In this figure, a magnetic head 10 has two magnetic head core parts (made of a magnetic material such as ferrite) 11 and 12 facing each other, and a gap 14 formed in the upper portion between the magnetic head core parts 11 and 12. Coils 18 are wound around coil guide grooves 15 and 16 and a coil opening 17 formed on the outer sides and at the center of the magnetic head core parts 11 and 12. Also, a slider surface 25 is formed on the top of the magnetic head core parts 11 and 12 by slide width restricting grooves 20 and 21. Non-magnetic mold glasses 22 and 23 are filled in the slider surface 25. The mold glasses 22 and 23 reinforce the exterior of the magnetic head 10 and forms the slider surface 25 on which magnetic tape slides. The mold glasses 22 and 23 also bond the two magnetic head core parts 11 and 12.
FIG. 2A is a plan view of the slider surface 25 of the conventional helical scan magnetic head device, and FIG. 2B is an enlarged view of the same slider surface 25. In the conventional helical scan magnetic head device, the slider surface 25 is defined by the slide width restricting grooves 20 and 21. However, the mold glasses 22 and 23 occupy a large area on the slider surface 25. Also, the abrasion resistance of the magnetic head core parts 11 and 12 is different from the abrasion resistance of the mold glasses 22 and 23. Since the mold glasses 22 and 23 have a large area on the slider surface 25, partial abrasion occurs between the magnetic head core parts 11 and 12 and the mold glasses 22 and 23 as the magnetic tape scanning time accumulates. This partial abrasion results in recession, which in turn leads to a wide space between the magnetic head and the magnetic tape at the time of scanning. Such a wide space results in poor sliding contact between the magnetic head and the magnetic tape.
USPTO Backgrounds
USPTO Backgrounds