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AssigneesKabushiki Kaisha Suwa Seikosha, Shinsu Seiki Kabushiki Kaisha
InventorsTadayoshi Shimodaira, Yoshihiro Mitsui
Estimating the term…
In a character-selecting mechanism for a printer, an electromagnet which controls the engagement and disengagement of a pawl with a ratchet and, thereby, the actual printing step, is supplemented with a permanent magnet having spaced-apart poles. A core arm lies within a core passage in the electromagnet and protrudes into the magnetic field produced by the permanent magnet. Activation of the electromagnet by a current pulse magnetizes the core arm to a polarity such that it is repelled by a pole next to which the core arm is disposed in a first position so that the core arm moves toward the other pole to take up a second position. During the transit from first to second position the core arm which is connected through a core member to a pawl brings the pawl into engagement with the ratchet. The energy requirement for effecting engagement of the pawl with the ratchet is substantially smaller than that of mechanisms relying on an electromagnet alone, whereby reducing both the size and the power consumption of such a printer.
An improvement in a printer mechanism for selecting for printing a character on a moving character support, said mechanism including an electromagnet coil having a core passage therethrough, a ratchet connected with said character support for controlling the movement thereof, wherein said improvement comprises a permanent magnet having a spaced-apart north and south poles generating a magnetic field, a shaft, a core member mounted on said shaft for rotation between first and second positions, said core member having a core arm of a ferromagnetic material and a pawl extending from said shaft in a direction substantially opposed to said core arm and including a pawl for engaging said ratchet when said core member is in said second position, said core arm, in part, lying within said core passage and adapted to reciprocate therein about said shaft and including a tip portion at the end of said core arm extending through said coil, said tip portion proximate one of said poles when said core arm is in said first position and proximate the other of said poles when said core arm is in said second position, said core arm in said first position being held to said one pole by said magnetic field in the absence of current flow through said electromagnet, and in said second position being held to said other pole by said magnetic field, said electromagnet being so connectable electrically that on activation thereof by a current pulse, said core arm becomes of the same polarity as said one pole and is repelled thereby for moving said arm toward and into engagement with the other of said poles, and for thereby engaging said pawl with said ratchet, and mechanical reset means for returning said core arm and core member to said first position and disengaging said pawl from said ratchet, and wherein said core member has a side arm of a ferromagnetic material extending from said core member at the region of said shaft in the direction of said core arm and further comprising a second permanent magnet disposed proximate the tip region of said side arm for attracting said side arm for pivoting said core member about said shaft from said first to said second position on activation of said electromagnet by a current pulse.
Dependencies are inferred from the claim text.