Patent ID: 8269759
Filing Date: 2012-09-18
Classification: G09G

Abstract:
1. A pixel driving device for driving a plurality of pixels, connected to each of a plurality of signal lines, and each comprising a light emitting element, and a pixel drive circuit having a drive transistor, which is for controlling current supplied to the light emitting element, and whose one end of a current path is connected to one terminal of the light emitting element, the pixel drive circuit further having a holding capacity for storing charge by voltage impressed on a control terminal of the drive transistor, the pixel driving device comprising: a voltage impressing circuit for outputting a reference voltage; a plurality of voltage measurement circuits equipped for connecting to each signal line; a switching circuit for switching connection of one end of each signal line, between the voltage impressing circuit and each voltage measurement circuit; and a property parameter acquisition circuit for acquiring property parameters that relate to electrical properties of each pixel; wherein the reference voltage has an electric potential in which an electric potential difference of the one end with respect to the other end of the current path of the drive transistor is a value that exceeds a threshold voltage of the drive transistor; wherein the switching circuit connects the one end of each signal line to the voltage impressing circuit and interrupts the connection between the one end of each signal line and the voltage impressing circuit after impressing the reference voltage for a predetermined time on the one end of each signal line by the voltage impressing circuit, and connects the one end of each signal line to each voltage measurement circuit after a predetermined settling time has elapsed; wherein each voltage measurement circuit acquires a voltage of the one end of each signal line as a measured voltage when connected with the one end of each signal line by the switching circuit; wherein the settling time is set to a value of a first settling time group and a value of a second settling time; wherein the first settling time group is constituted with a plurality of different time values, each of which is larger than a ratio (C/β0) where C is total capacity, which is, the sum of a parasitic capacity that is parasitic on a single signal line, a holding capacity, and a light emitting element capacity that is parasitic on the light emitting element, and β0 is a reference value of a current amplification factor; and the second settling time is constituted with a time value which is shorter than the ratio (C/β0); and wherein the property parameter acquisition circuit acquires the threshold voltage of the drive transistor for each pixel and the current amplification factor of the pixel drive circuit as a first property parameter in the property parameters based on voltage values of a plurality of measured voltages acquired by the plurality of voltage measurement circuits for the first settling time group; and the property parameter acquisition circuit acquires an irregularity parameter which indicates an irregularity of the current amplification factor as a second property parameter in the property parameters based on a value of the threshold voltage acquired for each pixel and values of measured voltages acquired by the voltage measurement circuits for the second settling time.