Self-scanning light-emitting element array and driving method of the same
A self-scanning light-emitting element array is driven such that, if a current supply line for a light-emitting element is broken, a light-emitting element neighboring failed light-emitting element continues to operate. In first time period turned-on states of the neighboring two thyristor overlap when the turned-on state is transferred in the transfer portion by the two-phase clock pulses; a second time period is provided after the first period, during which the light-emitting thyristor corresponding to the turned-on thyristor in the transfer portion is lighted by the light-emitting signal; in a third time period, after the second time period, a turned-off transfer thyristor for the turned-on thyristor is turned on and the lighted thyristor in the light-emitting portion is lighted out. The second time period has a length in which the thyristor having the broken line neighboring the failed thyristor is lighted.
1. A method for driving a self-scanning light-emitting element array including a transfer portion in which a plurality of three-terminal light-emitting thyristors are arrayed in one dimension, gates of neighbored thyristors are connected by a diode respectively, a power supply is connected to each gate of the thyristors through a load resistor, a first and second clock pulses of two phases are alternately supplied to cathodes or anodes of the thyristors; a light-emitting portion in which a plurality of three-terminal light-emitting thyristors are arrayed in one dimension, each gate of the thyristors is connected to a gate of corresponding thyristor in the transfer portion through a resistor, and a light-emitting signal is supplied to cathodes or anodes of the thyristors; the method comprising the steps of: turning on the thyristors in the transfer portion sequentially by the two-phase clock pulses; lighting the thyristor in the light-emitting portion corresponding to the turned-on thyristor in the transfer portion by the light-emitting signal; a first time period is provided, during which turned-on states of neighbored two thyristors are overlapped when the turned-on state is transferred in the transfer portion by the two-phase clock pulses; a second time period is provided after the first time period, during which the thyristor in the light-emitting portion corresponding to the turned-on thyristor in the transfer portion is lighted by the light-emitting signal; a third time period is provided after the second time period, during which a turned-off thyristor following the turned-on thyristor in the transfer portion is turned on as well as the lighted thyristor in the light-emitting portion is lighted out; and the second time period is a time period having a length in which when a thyristor to be lighted in the light-emitting portion is not lighted due to the breakage of a line, a thyristor following the failed thyristor due to the breakage of the line is lighted.
2. The method according to claim 1 , wherein the second time period is determined by the variation of the gate voltages of the thyristor following the failed thyristor and the thyristor prior to the failed thyristor.
3. A method for driving a self-scanning light-emitting element array including a transfer portion in which a plurality of three-terminal light-emitting thyristors are arrayed in one dimension, gates of neighbored thyristors are connected by a diode respectively, a power supply is connected to each gate of the thyristors through a load resistor, a first and second clock pulses of two phases are alternately supplied to cathodes or anodes of the thyristors; a light-emitting portion in which a plurality of three-terminal light-emitting thyristors are arrayed in one dimension, each gate of the thyristors is connected to a gate of corresponding thyristor in the transfer portion through a resistor, and a light-emitting signal is supplied to cathodes or anodes of the thyristors; the method comprising the steps of: turning on the thyristors in the transfer portion sequentially by the two-phase dock pulses; lighting the thyristor in the light-emitting portion corresponding to the turned-on thyristor in the transfer portion by the light-emitting signal; a first time period is provided, during which turned-on states of neighbored two thyristors are overlapped when the turned-on state is transferred in the transfer portion by the two-phase clock pulses; a second time period is provided after the first time period, during which the thyristor in the light-emitting portion corresponding to the turned-on thyristor in the transfer portion is lighted by the light-emitting signal; a third time period is provided after the second time period, during which the lighted thyristor in the light-emitting portion is lighted out; a fourth time period is provided after the third time period, during which a thyristor following the turned-on thyristor in the transfer portion is turned on; and the fourth time period is a time period having a length in which when a thyristor to be lighted in the light-emitting portion is not lighted due to the breakage of a line, a thyristor prior to the failed thyristor due to the breakage of the line is lighted.
4. The method according to claim 3 , wherein the fourth time period is determined by the variation of the gate voltages of the thyristor back to following the failed thyristor and the thyristor prior to the failed thyristor.