Abstract: A wafer production method includes forming, in an ingot, a separating layer that includes modified portions and cracks, by relatively moving the ingot and a focal point of a laser beam, with the focal point positioned at a depth corresponding to a thickness of the wafer, separating the wafer from the ingot by using the separating layer as a separation starting interface, bonding an adhesive tape to at least one of a separated surface of the wafer and a resulting fresh end surface of the ingot, removing separation debris stuck on the at least one surface, by separating the adhesive tape from the at least one surface, and grinding the at least one surface from which the separation debris has been removed. A wafer production machine is also disclosed.

Abstract: A grinding wheel is mounted on a tip end of a spindle and the grinding wheel grinds a workpiece according to rotation of the spindle. The grinding wheel includes an annular base, and a plurality of grindstone sets disposed in an annular manner on one surface side of the base along a circumferential direction of the base. Each of the plurality of grindstone sets has a first grindstone and a second grindstone having a self-sharpening capability lower than that of the first grindstone, such that the first grindstone and the second grindstone are adjacent to each other in a predetermined orientation in the circumferential direction of the base, and a predetermined interval larger than an interval between the first grindstone and the second grindstone in the circumferential direction of the base is provided between adjacent ones of the grindstone sets.

Abstract: A first main information signal is recorded in a first track extending longitudinally along one side of a length of magnetic tape and a corresponding first secondary, or control, signal is recorded in a narrow parallel track spaced from the first main track. A second main signal is recorded in a third track within the other half of the tape, and a corresponding second secondary, or control, signal is recorded between the first secondary signal and the first main signal, whereby the two main signals and the two secondary signals are interleaved with each other. The first and second main tracks are equal in width, and the first and second secondary tracks are also equal in width but are much narrower than the first and second main tracks.

Abstract: A random access system for recording and/or reproducing apparatus of the type used for recording information on and/or reproducing information from addressable portions of a record medium. The random access system is capable of recording address signals on the medium adjacent corresponding addressable portions and of playing back address signals from the medium so as to access any addressable portion thereof to reproduce information therefrom. The address signals are constituted by a variable number of address pulses plus a constant number of pulses. The random access system includes a counter for counting pulses which are applied thereto so as to derive a count corresponding to an address. A detector detects the constant number of pulses included in an address signal and supplies only the variable number of address pulses to the counter.

Abstract: In an apparatus for recording and/or reproducing audio or other information signals in one or more record tracks on a face of a magnetic tape as the latter is guided in a predetermined path, for example, from a supply reel to a take-up reel; a magnetic head is disposed adjacent such path to engage an edge surface of the tape substantially at right angles to the face thereof for recording and/or reproducing a control signal in the tape from such edge surface, whereby to make available an increased proportion of the width of the tape for the record tracks and guard bands therebetween. Preferably, the head for recording and/or reproducing the control signal in the tape from an edge surface thereof is mounted at a tape guide member by which the tape is positioned in the direction of its width.

Abstract: A circuit to control the frequency response of a variable filter by means of a control signal based on the amplitude of the information signal to minimize the effect of noise in a signal transmission system. The variable filter is connected to an output circuit of an information signal amplifier and may feed the frequency-modified information signal to a system output terminal, if the system is to compress the dynamic range of the information signal by amplifying low amplitude signals more than high amplitude signals. Alternatively, the filter may feed the frequency-modified signal back to the input of the amplifier by way of connecting means, such as switch, to expand the dynamic range. Control of the filter for low frequency signals is achieved by rectifying and filtering the signals to the control amplifier. Negative-going transients are inverted and by-pass the rectifier and filter and are applied directly to the control amplifier.