| 摘要 |
<p>PURPOSE:To attain the optical discrimination for the dots which emit light simultaneously within the same column by inserting the non-light emitting periods with mutual shifts into the light emitting periods of anode dot segments to which the drive pulses are impressed simultaneously. CONSTITUTION:The drive pulses are applied simultaneously to the anode dot segments within the same column. In this case, the cuts are given to each drive pulse with the timing in response to the row positions of those dots. These timings are shifted from each other according to the column positions and therefore the row positions can be recognized by detecting the length of tk by a photodetecting element 21 of a light pen 2 set on a face plate 11 of a fluorescent display tube 1. The emission of light of each dot is detected by the element 21 consisting of a photodiode, etc. through a lens 22 and undergoes the amplification and shaping through an amplifying/shaping circuit 23. Then, the fall differential output is sent to a circuit which detects the dot positions. The cut width T1 in the drive pulse is generally set at several musec and sufficient. This value of the T1 is equal just to one to several tens of the entire light emitting period and therefore gives virtually no effect to the light emitting luminance.</p> |
