GB852533A - Improvements relating to magnetic recording and reproducing heads - Google Patents

Abstract

852,533. Magnetic recording heads. PHILIPS ELECTRICAL INDUSTRIES Ltd. July 23, 1957 [July 26, 1956], No. 23291/57. Class 40 (2). A method of manufacturing magnetic recording and reproducing heads is characterized by a procedure to enable the height of the gap to be accurately determined. Fig. 2 shows two portions of the ferromagnetic circuit, the surface 9 of part 7 being longer in the direction of the gap height (h<SP>1</SP>) than the corresponding surface 10 of part 8 and in the assembled position extending beyond the upper and lower edges of surface 10. A layer of glass 4 between the surfaces, which is a little thicker than the required gap dimension, is heated to softening-point and pressure is applied to parts 7 and 8 to reduce the gap to the desired figure. After cooling, the dimension h<SP>1</SP> is achieved by machining away the shaded portions 12 and 13. Since the lower edge of surface 10 always lies within the surface 9 then the height h<SP>1</SP> of the part 8 will also be the gap height. Shaded parts 15a and 15b are subsequently removed to provide a seating for a closing yoke. In a modification (Fig. 3) the magnetic circuit comprises only two parts, one U-shaped, 17, and the other a flat bar, 16, forming at one of its junctions a glass-filled magnetic gap 4. In a further modification (Fig. 4) the magnetic circuit is constructed with two glass-filled magnetic gaps 31, 32. The assembly is divided along the line 41-41 into two parts each containing one magnetic gap, each circuit being completed by a closing yoke. By slitting along the lines 42, 43 the assembled block may be divided into a number of narrower heads.