| 摘要 |
The principal structure of the case of a cartridge (503) comprises an upper case (100) and a lower case (120). The upper case (100) is made of a plastic and on its inner surface a conductive layer is formed. The lower case (120) is made of aluminum. On the periphery of the lower case (120) a wall-like engagement section (124) is provided, and the engagement section (124) is engaged with the side surface of the upper case (100) to constitute a nearly rectangular parallelepiped case. The outer peripheral surface of the engagement section (124) and the inner side surface of the upper case (100) constitute a double conductive layer, and thereby, electromagnetic wave noises are prevented from leaking. Also, the signal-ground and the frame-ground of a printed circuit board (550) are earthed at multiple points, and high frequency noises are prevented. At an opening (142) through which the plug section (551) of the print-circuit board (550) is protruded to the outside, the conductive layer is ended, and the electromagnetic wave noises tend to leak to the outside. However, the signal-ground and frame-ground of the printed circuit board are earthed near both the end parts and the middle part of the plug section (551), and thereby, the generation of the harmful electromagnetic noises is reduced. <IMAGE> |
