Organic EL drive circuit and organic EL display device using the same

An organic EL drive circuit including a D/A converter circuit which has a current mirror circuit having a plurality of output side transistors connected in parallel in current mirror manner and an input side transistor portion supplied with a predetermined current, said output side transistors corresponding to bit positions of input data, respectively, and selectively operating according to the input data, and said D/A converter circuit generating at an output terminal thereof converted analog current corresponding to the input data as a total current of said output side transistors, said organic EL drive circuit comprising:

• a plurality of parallel connected input side transistors provided in said input side transistor portion;
• a plurality of switch circuits connected in series with said input side transistors, respectively,
• a current source for driving said input side transistors with a predetermined constant current;
• and
• a control circuit for ON-OFF controlling said switch circuits, said control circuit reducing a drive current of one of said input side transistors by turning at least one of said switch circuits ON to drive said one of said input side transistors with said predetermined constant current and turning at least one of the remaining switch circuits ON after a predetermined time from a drive start time to branch the constant current to at least one of said input transistors to thereby generate the converted analog current having a peak current in said output side transistor portion.

An organic EL drive circuit having a current mirror circuit responsive to a predetermined current to input side transistors for generating a current to be supplied to a terminal pin of an organic EL panel or a basic current from which the currents are obtained in output side transistors, said organic EL drive circuit comprising:

• a first input side transistor and a second input side transistor connected in parallel to the first input side transistor;
• a switch circuit connected in series with said second input side transistor;
• a constant current source for driving said first input side transistor with a predetermined current;
• and
• a control circuit for ON-OFF controlling said switch circuit,
• wherein said first input side transistor is driven by the constant current and a current having a peak is generated in said output side transistors by reducing the drive current for each of said current mirror circuit by branching a constant current value of the predetermined current to said second input side transistor by turning said switch circuit ON after a predetermined time from a drive start time.

An organic EL display device comprising:

• an organic EL display panel;
• a current mirror output circuit for outputting currents to terminal pins of said organic EL display panel;
• a D/A converter circuit having a current mirror circuit including a plurality of parallel input side transistors supplied with a predetermined current and a plurality of parallel output side transistors, said output side transistors corresponding to respective bit positions of display data and selectively operating according to the display data, said D/A converter circuit converting the display data into analog current to generate the analog current as a total of currents of said output side transistors;
• and
• a control circuit for driving one of said input side transistors with a predetermined current to generate a peak current in said output side transistors and reducing the peak current in said output side transistors to a steady current by branching the predetermined current in said one input side transistor to the other input side transistors parallel to said one input side transistor.

An organic EL display device comprising:

• an organic EL display panel;
• a current mirror output circuit for outputting currents to terminal pins of said organic EL display panel;
• a D/A converter circuit having a current mirror circuit including a plurality of parallel input side transistors supplied with a predetermined current and a plurality of parallel output side transistors, said output side transistors corresponding to respective bit positions of display data and selectively operating according to the display data, said D/A converter circuit converting the display data into analog current to generate the analog current as a total of currents of said output side transistors;
• switch circuits connected in series with said second input side transistors;
• a constant current source for driving said first input side transistor with a predetermined constant current;
• and
• a control circuit for ON-OFF controlling said switch circuit,
• wherein said first input side transistors are driven by the constant current and a current having a peak is generated in said output side transistors by reducing the drive current for each of said current mirror circuits by branching the constant current to said second input side transistors by turning said switch circuits ON after a predetermined time from a drive start time.