| 摘要 |
PURPOSE:To always record and reproduce the normal information signals by adding a working range control means made of a magnetic adsorbing member to a holder and one of two substrates and at the same time forming a gap larger than the difference of diameters between the magnetic adsorbing member and the working range control means at a place between the adhered part of the holder and the substrate and the magnetic adsorbing member. CONSTITUTION:A working range control means made of a magnetic adsorbing member 3 is provided to a holder 4. Thus a gap is secured between the holder 4 and the member 3 to store the excessive adhesive produced when the holder 4 is adhered to the substrates 2 and 2a. Thus the member 3 is never adhered by mistake. At the same time, a gap is secured between an outer circumferential projection 10 of the holder 4 and the outer circumferential of the member 3. As a result, the strains produced by the difference of expansion rates between the substrates 2/2a and the member 3 are absorbed by the gap formed between the member 3 and the holder 4. Thus no stress is applied to both substrates 2 and 2a and therefore the reproduction signals of high S/N can be obtained.
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