| 摘要 |
<p>PURPOSE:To enhance yield of production of an LED printing head, by driving each light-emitting diode according to an output from a driving information storage means corresponding thereto. CONSTITUTION:Each LED 4-n is operated one at a time, the quantity of light thus emitted is measured by a measuring instrument, and the measured value is digitized. The digitized value is compared with a numberical value of a reference quantity of light, and an energization time necessary for obtaining the reference quantity of light under a fixed current is calculated. The energization time thus calculated is written and stored into a PLD timer 2-n corresponding to each LED 4-n. For example, assuming that an energization time T is necessary for an LED 4-1 to emit the reference quantity of light, PLD timers 2 transmit signals a-n with successive delays of 1/2 times the signal duration in response to a starting signal, but the signals h-n are cut off due to the energization time T stored in the timer 2-1. With an output 7 from a shift register inputted to the timer 2-1, the signals a-g are continuously transmitted to a driver 3, which outputs a current to the LED 4-1 for the energization time T, whereby the LED 4-1 emits light in the reference quantity.</p> |
