Drive chip, drive circuit and drive method capable of eliminating LED ghost
Disclosed are drive chip, drive circuit and drive method capable of eliminating LED ghost. The drive chip comprises a processing unit, a blanking unit and a constant current drive unit. By blanking unit, parasitic capacitances of each row of scanning lines of an LED array is discharged during a blanking period, eliminating an upper ghost without needing to pull down additional circuits such as a resistor, no caterpillar effect or the reverse bias of LED lamp beads; charging parasitic capacitance of each column of scanning lines of the LED array, eliminating lower ghost. By constant current drive unit, constant current control is performed on LED lamp beads. Performing blanking and constant current control individually in two time periods, when displaying LED lamp beads, parasitic capacitance and both upper and lower ghosts are eliminated.
1. A drive chip capable of eliminating a Light Emitting Diode (LED) ghost, comprising:
a processing circuit configured to divide a display cycle into a blanking period and a Pulse Width Modulation (PWM) output period, wherein the processing circuit is further configured to send a blanking control signal to a blanking circuit during the blanking period, and send a PWM signal to a constant current drive circuit according to display data during the PWM output period;
the blanking circuit configured to discharge a plurality of parasitic capacitances in each row of scanning lines in an LED array during the blanking period, and charge a plurality of parasitic capacitances in each column of the scanning lines in the LED array, according to the blanking control signal; and
the constant current drive circuit configured to control a brightness of LED lamp beads of the LED array according to the PWM signal during the PWM output period, wherein:
the blanking period includes a first period and a second period, the first period being started before a row of scanning lines finishes scanning, and the second period being started after the row of scanning lines finishes scanning, and
an output terminal of the blanking circuit is coupled to each column of the scanning lines of the LED array, and the blanking circuit is configured to output a first voltage to each column of the scanning lines during the first period and output a second voltage to each column of the scanning lines during the second period.
2. The drive chip according to claim 1 , wherein the first voltage is higher than the second voltage.
3. The drive chip according to claim 2 , wherein the second voltage is higher than a difference between a power source voltage and a conduct voltage of the LED lamp beads.
4. The drive chip capable according to claim 1 , wherein the blanking period is a PWM output period gap between each pair of two lines in the LED array.
5. A drive circuit capable of eliminating the LED ghost comprising the drive chip according to claim 1 , wherein the drive circuit further comprises:
a power source configured to supply power to the drive circuit;
the LED array including a plurality of the LED lamp beads;
a master a circuit configured to output the display data to the drive chip, and drive progressively each row of the scanning lines of the LED array through a switch circuit; and
the switch circuit configured to control a switch between the rows of the scanning lines of the LED array and the power source, according to a control signal outputted from the master circuit.
6. The drive circuit according to claim 5 , wherein the power source connects to the rows of the scanning lines of the LED array through the switch circuit, a row control terminal of the master circuit connects to a control signal input terminal of the switch circuit, a data output terminal of the master circuit connects to an input terminal of the drive chip, an output terminal of the drive chip connects to the columns of the scanning lines of the LED array.
7. The drive circuit according to claim 6 , wherein the master circuit comprises:
a master sub-circuit configured to output the control signal to a code translation drive circuit, and output the display data to the drive chip;
the code translation drive circuit configured to translate the control signal, and control the switch circuit to drive a row of the scanning lines of the LED array according to a translated signal.
8. A drive method capable of eliminating a Light Emitting Diode (LED) ghost, comprising:
dividing a display cycle of an LED array into a blanking period and a Pulse Width Modulation (PWM) output period;
discharging a plurality of parasitic capacitances in each row of the scanning lines in the LED array, and charging a plurality of parasitic capacitances in each column of the scanning lines in the LED array during the blanking period;
controlling a brightness of LED lamp beads of the LED array during the PWM output period, wherein:
the blanking period includes a first period and a second period, the first period being started before a row of scanning lines finishes scanning, and the second period being started after the row of scanning lines finishes scanning, and
the method further includes: outputting a first voltage to each column of the scanning lines during the first period and outputting a second voltage to each column of the scanning lines during the second period.
9. The drive method according to claim 8 , wherein the first voltage is higher than the second voltage.
10. A drive chip capable of eliminating a Light Emitting Diode (LED) ghost, comprising:
a processing circuit configured to divide a display cycle into a blanking period and a Pulse Width Modulation (PWM) output period, wherein the processing circuit is further configured to send a blanking control signal to a blanking circuit during the blanking period, and send a PWM signal to a constant current drive circuit according to display data during the PWM output period;
the blanking circuit configured to discharge a plurality of parasitic capacitances in each row of scanning lines in an LED array during the blanking period, and charge a plurality of parasitic capacitances in each column of the scanning lines in the LED array, according to the blanking control signal; and
the constant current drive circuit configured to control a brightness of LED lamp beads of the LED array according to the PWM signal during the PWM output period, wherein:
the blanking period includes a first period and a second period,
an output terminal of the blanking circuit is coupled to each column of the scanning lines of the LED array, and the blanking circuit is configured to output a first voltage to each column of the scanning lines during the first period and output a second voltage to each column of the scanning lines during the second period,
in response to the first voltage during the first period, parasitic capacitances of the LED lamp beads in a row of the scanning lines are discharged, and the parasitic capacitances in each column of the scanning lines in the LED array are charged, and
in response to the second voltage during the second period, charges of the parasitic capacitances of the row line of the scanning lines are discharged to the parasitic capacitances of the LED lamp beads in the row.