# US 5,703,840 A · Magnetic head and magneto-optical recording device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,703,840 A - Document ID: US5703840A - Status: Granted - Kind: A - Application number: 08/770,608 - Filed: 1996-12-19 - Granted: 1997-12-30 - Earliest claimed: 1994-04-13 - Assignees: Alps Electric Co., Ltd. - Inventors: Tohio Kazama - Web page: https://patentgrep.com/patent/US5703840A ## CPC - G11B 11/10534: {for recording by magnetising, demagnetising or transfer of magnetisation, by radiation, e.g. for thermomagnetic recording} - G11B 5/1278: {specially adapted for magnetisations perpendicular to the surface of the record carrier} - G11B 11/1058: {Flying heads} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) ## Abstract An E-shaped core is composed of a main core and side cores which are combined into one piece. A coil is wound around a bobbin which is inserted in the main core. A plate-shaped auxiliary core is connected to a sliding member. Connecting the E-shaped core and the auxiliary core completes the assembly of the magnetic head for a magneto-optical recording device. The auxiliary core surrounds the main core; therefore, the concentration of the magnetic flux at the end of the main core can be enhanced and the efficiency for generating magnetic field for a recording medium can be improved. In addition, the use of the E-shaped core and the plate-shaped auxiliary core permits easier machining of the cores. ## Claims ### Claim 1 A magnetic head for a magneto-optical recording device in which the magnetic head is disposed adjacent a surface of a recording medium, said magnetic head comprising: a magnetic core formed from a first integral piece of magnetic material, the magnetic core including: an elongated base member; a main core portion extending perpendicular to the base member, the main core portion having a fixed end fixedly connected to the base member, and a free end located further from the base member than the fixed end; and a side core portion extending perpendicular to the base member and parallel to the main core portion, the side core portion having a fixed end fixedly connected to the base member and a free end located further from the base member than the fixed end, the free end of the side core portion being spaced a first distance from said main core portion; a coil wound around the main core portion such that a portion of the coil is located between the main core portion and the side core portion; and an auxiliary core formed from a second integral piece of magnetic material which is separate from said first integral piece, the auxiliary core contacting the free end of the side core portion and having a central portion extending from the side core portion toward the main core portion, the central portion defining an opening having an edge which is spaced a second distance from the free end of the main core portion such that a magnetic gap is formed between the edge and the free end of said main core portion; wherein the first distance is greater than the second distance such that magnetic flux generated by the main core portion flows from the free end of the main core portion across the magnetic gap and along a return path formed by the auxiliary core and the side core portion. ### Claim 2 (depends on 1) A magnetic head for the magneto-optical recording device according to claim 1, wherein said auxiliary core is composed of a plate defining said opening and the free end of said main core portion is inserted in said opening. ### Claim 3 (depends on 2) A magnetic head for the magneto-optical recording device according to claim 2, wherein said auxiliary core is connected to a sliding member which faces the surface of said recording medium. ### Claim 4 (depends on 3) A magnetic head for the magneto-optical recording device according to claim 3, wherein said coil is wound around a bobbin, said bobbin being mounted over said main core portion, and wherein a portion of the bobbin is located between the free end of the main core portion and the edge of the central portion of the auxiliary core. ### Claim 5 (depends on 3) A magnetic head for the magneto-optical recording device according to claim 3, wherein said sliding member is connected to the free end of said main core portion which faces said recording medium. ### Claim 6 (depends on 3) A magnetic head for the magneto-optical recording device according to claim 3, wherein said sliding member is provided on a surface of said auxiliary core which faces said recording medium. ### Claim 7 (depends on 2) A magnetic head for the magneto-optical recording device according to claim 2, wherein first and second rail surfaces are provided on a surface of said auxiliary core which faces said recording medium such that a groove is provided between the first and second rail surfaces. ### Claim 8 A magneto-optical recording device for reading information from and recording information to a recording medium, the magneto-optical recording device comprising an E-shaped magnetic head including: a magnetic core formed from a first integral piece of magnetic material, the magnetic core including: an elongated base member having a center located between a first end and a second end; a main core portion extending perpendicular to the base member, the main core portion having a fixed end located at an intersection of the main core portion and the base member and located adjacent the center of the base member, the main core portion having a free end spaced away from the base member; a first side core portion extending perpendicular to the base member and parallel to the main core portion, the first side core portion having a fixed end located at an intersection of the first side core portion and the base member near the first end, and a free end spaced away from the base member, the free end of the first side core portion being spaced a first distance from said main core portion; and a second side core portion extending perpendicular to the base member and parallel to the main core portion, the second side core portion having a fixed end located at an intersection of the second side core portion and the base member near the second end, and a free end spaced away from the base member, the free end of the second side core portion being spaced a second distance from said main core portion, the second distance being substantially equal to the first distance; a coil wound around the main core portion such that a first portion of the coil is located between the main core portion and the first side core portion, and a second portion of the coil is located between the main core portion and the second side core portion; an auxiliary core formed from a second integral piece of magnetic material, the auxiliary core contacting the free ends of the first and second side core portions and having central portions respectively extending from the first and second side core portions toward the main core portion, the central portions defining an opening having an edge which is spaced a third distance from the free end of the main core portion such that a magnetic gap is formed between the edge and the free end of said main core portion; wherein the first distance is greater than the third distance such that magnetic flux generated by the main core portion flows from the free end of the main core portion across the magnetic gap and along return paths formed by the auxiliary core and the first and second side core portions. ### Claim 9 (depends on 8) A magnetic head for the magneto-optical recording device according to claim 8, wherein said auxiliary core is a plate defining the opening, wherein said coil is wound around a bobbin, said bobbin being mounted over said main core portion, and wherein a wall of the bobbin is located between the edge of the opening and the free end of the main core portion. ### Claim 10 (depends on 9) A magnetic head for the magneto-optical recording device according to claim 9, wherein said auxiliary core is connected to a sliding member. ### Claim 11 (depends on 9) A magnetic head for the magneto-optical recording device according to claim 9, wherein first and second rail surfaces are provided on a surface of said auxiliary core which faces said recording medium such that a groove is provided between the first and second rail surfaces.