Display device that sets a value of a power supply voltage to compensate for changes in light emitting element I/V characteristics

A display device comprising:

• a plurality of display pixels that are arranged two-dimensionally and each have a first light emitting element and a drive transistor;
• and
• at least one adjustment pixel that has a reference light emitting element;
• a drive section configured to drive the plurality of display pixels to emit light at respective gradations corresponding to respective video signals input to the plurality of display pixels,
• wherein the drive section is configured to apply a display power-supply voltage to the plurality of display pixels when they emit light,
• a processing section configured to set a value of an adjustment-pixel signal during a given field period to be no larger than a largest value of the video signals input to the plurality of display pixels during the given field period, and
• a value of the display power-supply voltage is variably set such that, during a given field period, the value of the display power-supply voltage is a smallest value that will ensure that, for each of the plurality of display pixels an operation point of the light emitting element thereof during the given field period is within a saturation region of the drive transistor thereof,
• wherein the drive section is configured to
• drive the adjustment pixel to emit light at a gradation corresponding to the adjustment-pixel signal,
• determine a voltage variation of the reference light emitting element when it emits light, and
• generate the display power-supply voltage by adding the voltage variation of the reference light emitting element to a predetermined voltage value that corresponds to the adjustment-pixel signal, and
• wherein the processing section is configured to,
• during the given field period, update a value of the adjustment-pixel signal every horizontal scanning period such that the value of the adjustment-pixel in the horizontal scanning period in which the update is performed is no larger than a largest value of the video signals input to the plurality of display pixels from the start of the given field period to the horizontal scanning period in which the update is performed.

A method of driving a display device comprising a plurality of display pixels that are arranged two-dimensionally and have first light emitting elements and at least one adjustment pixel that has a reference light emitting element, the method comprising:

• causing the plurality of display pixels to emit light at respective gradations corresponding to respective video signals input to the plurality of display pixels and causing the at least one adjustment pixel to emit light at a gradation corresponding to an adjustment-pixel signal;
• setting a value of the adjustment-pixel signal during a given field period to be no larger than a largest value of the video signals input to the plurality of display pixels during the given field period;
• applying a display power-supply voltage to the plurality of display pixels when they emit light;
• variably setting the display power-supply voltage to a value depending on a voltage variation of the reference light emitting element when the reference light emitting element emits light, and
• wherein during the given field period, updating a value of the adjustment-pixel signal every horizontal scanning period such that the value of the adjustment-pixel in the horizontal scanning period in which the update is performed is no larger than a largest value of the video signals input to the plurality of display pixels from the start of the given field period to the horizontal scanning period in which the update is performed.