DA converter, data line driving circuit, electro-optical device, driving method thereof, and electronic apparatus
To simplify s configuration of a current mode DA converter. A data line driving circuit includes DA converting units U 1 to Un. Each DA converting unit U 1 to Un a voltage DA converting circuit for generating an analog voltage signal Sv based on image data, a V/I converting circuit for converting the analog voltage signal Sv into an analog current signal Si, and a voltage current selector for selecting one of the analog voltage signal Sv and the analog current signal Si based on a pre-charge control signal CTL. In addition, the analog voltage signal Sv outputted from the voltage current selector serves as a pre-charge voltage, and the analog current signal Si serves as a driving current of an OLED element.
1. A DA converter comprising:
reference voltage generating means for generating a plurality of reference voltages;
voltage selecting means for selecting one of the plurality of reference voltages, based on data inputted thereto, and outputting an analog voltage signal; and
voltage to current converting means for converting the analog voltage signal into an analog current signal, the voltage to current converting means including:
a transistor for outputting the analog current signal based on a voltage applied to a gate electrode of the transistor; and
compensating means for compensating the analog voltage signal and applying the compensated analog voltage signal to the gate electrode of the transistor so that an effect due to voltage to current conversion characteristics, which varies depending on a threshold voltage of the transistor, is cancelled out.
2. The DA converter according to claim 1 ,
wherein the voltage to current converting means includes gain adjusting means for adjusting a gain of the voltage to current conversion based on gain control data.
3. A data line driving circuit connected to a plurality of data lines, comprising:
a plurality of DA converters provided corresponding to the plurality of data lines,
wherein each of the DA converters comprises the DA converter according to claim 1 .
4. A data line driving circuit connected to a plurality of data lines, comprising:
a plurality of DA converters provided corresponding to the plurality of data lines; and
reference voltage generating means for generating a plurality of reference voltages and supplying the plurality of reference voltages to the plurality of DA converters, respectively,
wherein each of the plurality of DA converters includes:
voltage selecting means for selecting one of the plurality of reference voltages, based on image data, and outputting the selected reference signal as an analog voltage signal; and
voltage to current converting means for converting the analog voltage signal into an analog current signal, the voltage to current converting means includes:
a transistor for outputting the analog current signal based on a voltage applied to a gate electrode of the transistor; and
compensating means for compensating the analog voltage signal and applying the compensated analog voltage signal to the gate electrode of the transistor so that an effect due to voltage to current conversion characteristics, which varies depending on a threshold voltage of the transistor, is cancelled out.
5. The data line driving circuit according to claim 3 ,
wherein each of the plurality of DA converters includes voltage current selecting means for selecting one of the analog voltage signal and the analog current signal, based on a select control signal, and outputting the selected signal to the data lines.
6. An electro-optical device comprising:
the data line driving circuit according to claim 5 ; and
control means for controlling the voltage current selecting means to output the analog voltage signal during a first interval from a start of one horizontal scan period until a predetermined time elapses, generating a signal for controlling the voltage current selecting means to output the analog current signal during a second interval until the one horizontal scan period ends after the first interval ends, and supplying the signal for controlling the voltage current selecting means to the voltage to current converting means of the plurality of DA converters, as the select control signal, respectively.
7. An electronic apparatus including the electro-optical device according to claim 6 .
8. A method of driving an electro-optical device comprising a plurality of data lines, a plurality of scan lines, and pixel circuits provided at intersections of the data lines and the scan lines, the pixel circuits including electro-optical elements with brightness controlled depending on a current supplied from the data lines, the method comprising:
converting image data into an analog voltage signal,
converting the analog voltage signal into an analog current signal,
selecting the analog voltage signal, from the analog voltage signal and the analog current signal, during a first interval from a start of one horizontal scan period until a predetermined time elapses,
selecting the analog current signal during a second interval until the one horizontal scan period ends after the first interval ends, and the selected signals are supplied to the data lines,
outputting from a transistor the analog current signal based on a voltage applied to a gate electrode of the transistor, and
compensating the analog voltage signal and applying the compensated analog voltage signal to the gate electrode of the transistor so than an effect due to voltage to current conversion characteristics, which varies depending on a threshold voltage of the transistor, is canceled out.