| 摘要 |
<p>PURPOSE:To detect the breakage of each light emitting element by a method wherein a predetermined voltage is supplied to one or more light emitting elements by a light emission control means, an electric current is converted to a voltage by a resistance, and whether the electric current normally flows is judged. CONSTITUTION:A printer body control part 41 issues a start signal to an LED breakage detection circuit 35 prior to printing. The LED breakage detection circuit 35 breaks a relay 33 for detecting an LED chip current, thereafter outputting an LED breakage detecting strobe signal, a shift clock, and a light emitting signal to an LED head 3 through OR gates 39, 38, 37, 36. Each of the signals is issued at a timing for emitting light-emitting elements forming the LED head 3 successively from one end. Since a resistance 32 is connected to the light emitting elements in series, all an electric current passing through the light-emitted elements also passes through the resistance 32. Therefore, whether an electric current is normally passed through the light emitting elements can be judged according to the judgement of a comparator 34 whether the resistance ends voltage of the resistance 32 is normal.</p> |
