| 摘要 |
PURPOSE:To prevent the amount of injected charges from being reduced by friction and enhance resolution and sharpness, by constituting a multi-needle electrode of staggered needle electrodes so that the pressure of contact of the electrode in a rear row with a doner roller is lower than that of the electrode in a front row. CONSTITUTION:The multi-needle electrode 1, e.g., a stylus electrode has a surface 4 which makes contact with a toner layer 3 on the doner roller 2, and of the surface 4, the part where the electrodes 1b in the rear row are additionally provided (between point B and point C) 4b is inclined an angle theta1 in the direction for gradually separating away from the toner layer, as compared with the part where the electrodes 1a in the front row are embedded (between point A and point B) 4b. Point B is set in proximity to the intersection of a straight line X-X passing through the center of the roller 2 and parallel to the axis of the stylus 1 with the surface 4. The part 4a forms a surface substantially tangent to the roller 2 or a surface parallel to said surface. Accordingly, the charges injected by the needle electrodes 1a in the front row are hardly decreased because the friction thereof with the part 4b is suppressed, and a high recorded density can be obtained. The angle theta1 is so selected that the needle electrodes in the rear row can securely make contact with the toner layer 3. |
