Other

Hitachi-kokusai Electric Inc.

Yoshiaki Fukuda

Yoshikazu Ito

Kazuhisa Aruga

Iichi Wako

Nobuyuki Matsui

Kanji Kawakami

In an antenna for communicating an electromagnetic wave, a first converger converges the electromagnetic wave. A second converger faces the first converger and includes a conductor plate having a through hole, into which a magnetic flux of the converged electromagnetic wave is converged. The through hole is formed at a center portion of the conductor plate so as to have a size which is sufficiently smaller than a wavelength of the electromagnetic wave. The conductor plate is formed with a cutout extending from a part of the through hole to an outer periphery of the conductor plate. A converter faces the through hole of the conductor plate to convert the converged magnetic flux into voltage.

Antenna

The invention provides an drive coil protection apparatus and method and a printer incorporating the apparatus. A rank memory stores a preset rank value associated with a reference drive coil in the print head of a printer. The preset rank value characterizes inherent deviations associated with the reference drive coil. The deviations result from manufacturing process, etc. A judgment value memory stores a plurality of sets of mode judgment values. Each set of mode judgment values corresponds to a particular rank value. Each mode judgment value represents a threshold value for determining the thermal condition of the print head and for selecting an appropriate operating mode for the print head. A head information detector detects the voltage drop across the reference drive coil to measure the change in the resistance of the reference drive coil. The voltage drop is digitized for accuracy measurement. The change in temperature of the reference drive coil can thus be determined. An operating mode selection circuit compares the digitized voltage drop with a particular set of mode judgment values in the judgment value memory corresponding to the preset rank value. Then, the operating mode selection circuit selects a suitable operating mode for the print head in accordance with the comparison. Thus, burnout of the print head can be prevented without reducing the operating efficiency of the printer.

Drive coil protection apparatus and method and printer incorporating the

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Tochigi, Japan

Yoshiaki Fukuda