Drive circuit, display device, and drive method
Drive circuits and display devices with reduced power consumption are disclosed. In one example, a drive circuit includes a setting circuit configured to precharge, to a first voltage, a video signal line connected to a first transistor configured to sample a voltage of the video signal line, and an adjustment circuit configured to adjust a voltage of the video signal line by charging or discharging the video signal line precharged to the first voltage during a time period corresponding to a second voltage set in the video signal line.
1. A drive circuit comprising:
a setting circuit that includes a first switch configured to connect, to a first voltage line, a video signal line connected to at least one pixel circuit that includes a light emitting element, and is configured to precharge the video signal line to a first voltage supplied from the first voltage line;
an adjustment circuit that includes a current source and a second switch configured to electrically connect the video signal line to the current source during a period according to a video signal, and is configured to adjust a voltage of the video signal line by charging or discharging the video signal line precharged to the first voltage with a current generated by the current source; and
a detection circuit that includes a first terminal connected to a second voltage line and a second terminal connected to the video signal line, and is configured to detect a difference between a second voltage supplied from the second voltage line and a voltage of the video signal line, wherein
the current source is configured to generate the current in accordance with the difference.
2. The drive circuit according to claim 1 , further comprising: a controller configured to supply a control voltage in accordance with the difference to a control terminal of the current source.
3. The drive circuit according to claim 2 , wherein
the controller is configured to store the control voltage and supply the voltage to the control terminal of the current source.
4. The drive circuit according to claim 1 , wherein
the detection circuit includes an amplifier configured to generate a control current in accordance with the difference, and the controller includes a capacitor configured to store a control voltage according to the control current.
5. The drive circuit according to claim 4 , further comprising:
a third switch that connects the first terminal and the second terminal, wherein
the adjustment circuit is configured to turn on the third switch for a time period before an operation of the amplifier.
6. The drive circuit according to claim 1 , wherein
the detection circuit includes a comparator configured to detect timing at which a voltage of the video signal line is the second voltage, and a phase comparator configured to detect a difference between the timing and timing according to the second voltage, and further comprising
a charge pump configured to generate a control current according to the difference, and
a controller that includes a capacitor configured to store a control voltage according to the control current and is configured to supply the control voltage to a control terminal of the current source.
7. The drive circuit according to claim 1 , wherein
the detection circuit includes a conversion circuit configured to convert the difference between the second voltage and a voltage of the video signal line into a digital signal and a digital to analog converter configured to supply a voltage according to the digital signal to a control terminal of the current source.
8. The drive circuit according to claim 1 , wherein
the first voltage includes a voltage corresponding to a maximum gradation or a minimum gradation.
9. The drive circuit according to claim 1 , wherein
the second voltage includes a voltage corresponding to a gradation that the pixel circuit is caused to display.
10. The drive circuit according to claim 1 , wherein
the second voltage includes an offset voltage for correcting a threshold voltage of a drive transistor for driving a light emitting element in the pixel circuit.
11. The drive circuit according to claim 10 , further comprising:
a scanning circuit configured to turn on a sampling transistor included in the pixel circuit and supply a voltage of the video signal line set to the offset voltage to a node in the pixel circuit, wherein
the setting circuit is configured to precharge the video signal line to the first voltage after the offset voltage is supplied to the pixel circuit,
the adjustment circuit is configured to adjust the voltage of the video signal line to a voltage corresponding to a gradation by charging or discharging the video signal line precharged to the first voltage during a time period according to the voltage corresponding to the gradation, and
the scanning circuit is configured to turn on the sampling transistor to supply the voltage of the video signal line to the node in the pixel circuit.