| 摘要 |
A compact, light weight, high speed, dot matrix printing head comprises a generally circular array of stylus drivers. The printing head employs a generally circular permanent magnet common to all drivers and mounted centrally of the device. Each driver includes an arm having a stylus secured at one end thereof generally perpendicular to the arm and an armature of an electromagnet mounted on the other end of the arm. A magnetic circuit of each driver includes a section of the permanent magnet and bucking coil electromagnet in a short generally rectangular structure with the armature located at one corner of the structure such corner formed by a pole of electromagnet and a pole of the permanent magnet. The arm is carried on crossed flexures providing a pivot point for the arm in the plane of the interface of the armature and pole of the electromagnet to reduce wear. The arrangement of the structure causes the air gap forces to produce moments which are additive. The rectangular arrangement permits the coil of the electromagnet to be the outermost component of each driver so that sufficient cooling of the coil may readily be provided to permit the high current operation required at the desired operating speeds (800 characters per second) without damage to the coils. The high current capacity of the coil and the compact magnetic structure permits reliable operation.
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