Light emitting element array, drive circuit, optical print head, and image forming apparatus
View Patent ↗A light emitting element array includes a plurality of light emitting elements each having a first terminal, a second terminal, and a third terminal. The light emitting elements are arranged next to each other to form a group. The first terminal receives a drive signal, the second terminal is connected to ground, and the third terminal has a threshold voltage or a threshold current controllable from outside so that the light emitting elements are driven in a time division way.
1. A drive circuit for driving a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way, comprising:
a plurality of drive elements for supplying the drive signal to the anodes of the light emitting thyristors;
a plurality of common base lines for flowing the control signal to control on/off of the light emitting thyristors; and
a plurality of individual circuits connected to the common base lines for supplying the control signal to the gates of the light emitting thyristors, said individual circuits having a function of shifting a level of the control signal,
wherein each of said individual circuits is formed of an n-type conductive switch element having a first switch terminal connected to one of the common base lines, a second switch terminal connected to the gate, and a third switch terminal connected to the second switch terminal for controlling a conductive state between the first switch terminal and the second switch terminal.
2. The drive circuit according to claim 1 , wherein each of said individual circuits is an N-channel MOS transistor having a source as the first switch terminal, a drain as the second switch terminal, and a gate as the third switch terminal.
3. An optical print head comprising,
a light emitting thyristor array including a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way;
a lens array for collecting light emitted from the light emitting element thyristor array; and
the drive circuit according to claim 1 .
4. An image forming apparatus comprising the optical print head according to claim 3 and a photosensitive member arranged to face the optical print head.
5. A drive circuit for driving a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way, comprising:
a plurality of drive elements for supplying the drive signal to the anodes of the light emitting thyristors;
a plurality of common base lines for flowing the control signal to control on/off of the light emitting thyristors; and
a plurality of individual circuits connected to the common base lines for supplying the control signal to the gates of the light emitting thyristors, said individual circuits having a function of shifting a level of the control signal,
wherein each of said individual circuits is formed of a p-type conductive switch element having a first switch terminal connected to the gate, a second switch terminal connected to one of the common base lines, and a third switch terminal connected to the second switch terminal for controlling a conductive state between the first switch terminal and the second switch terminal.
6. The drive circuit according to claim 5 , wherein each of said individual circuits is an P-channel MOS transistor having a source as the first switch terminal, a drain as the second switch terminal, and a gate as the third switch terminal.
7. An optical print head comprising,
a light emitting thyristor array including a plurality of light emitting thyristors each including an anode for receiving a drive signal to drive the light emitting thyristor, a cathode connected to ground, and a gate for receiving a control signal to drive the light emitting thyristor in a time division way;
a lens array for collecting light emitted from the light emitting element thyristor array; and
the drive circuit according to claim 5 .
8. An image forming apparatus comprising the optical print head according to claim 7 and a photosensitive member arranged to face the optical print head.