| 摘要 |
PURPOSE:To attain a high luminance and high resolution picture and to simplify the driving circuit, by applying a pulse signal voltage to a linear hot-cathode and making the potential difference between both ends almost zero temporarily. CONSTITUTION:When a voltage V1 is applied to a linear hot-cathode 20, the cathode 20 is in electron emitting state, and since a negative voltage is applied to a cylindrical barrier electrode 21, no electron is emitted. When a negative voltage is applied to the electrode 21, the electrode is kept at cut-off state over the entire length of the cathode 20. In this state, when a negative pulse voltage is applied to one end of the cathode 20 with a pulse voltage generator 33, the cathode is negative and electrons are emitted. In this case, at the other end of the cathode 20, a diode 32 receives inverse voltage, the potential difference across the cathode 20 is almost zero and the potential gradient toward axial direction is lost. Thus, electron beams with uniform and high current density are obtained and then sharp picture is obtained. Further, the number of electrodes is saved remarkably, the drive circuit is simplified and the cost is reduced. |
