Light emission drive circuit and its drive control method and display unit and its display drive method

A light emission circuit comprising:

• a selection line;
• a hold line;
• is a data line;
• a supplying voltage line;
• a hold transistor having a gate electrically connected to the hold line, and a current path;
• a drive transistor having a gate and a current path, the gate of the drive transistor being electrically connected to one end of the current path of the hold transistor and one end of the current path of the drive transistor being connected to the supplying voltage line;
• and
• a selection transistor having a gate and a current path, the gate of the selection transistor being electrically connected to the selection line, one end of the current path of the selection transistor being connected to the other end of the current path of the drive transistor, and the other end of the current path of the selection transistor being connected to the data line.

A drive control method of a light emission drive circuit, which supplies a light emission drive current to a light emission element to make the light emission element perform the light emission, comprising:

• setting a first potential difference equivalent to a threshold value of a transistor element, or a first potential difference equivalent to the minimum luminance voltage necessary for generating the light emission drive current required for making the light emission element perform the light emission operation at the minimum luminance gradation sequence between a gate and a source of a transistor element to supply the light emission drive current to the light emission element;
• applying a gradation sequence signal to make the light emission element perform the light emission operation at a luminance gradation sequence to the transistor element and setting a second potential difference in accordance with the luminance gradation sequence between the gate and the source of the transistor element;
• and
• turning on the transistor element at a predetermined conducting state on the basis of the second potential difference, generating the light emission drive current having a current value in accordance with the luminance gradation sequence, and supplying it to the light emission element.

A display unit comprising:

• a plurality of display pixels each of which includes a light emission element and a light emission drive circuit having an electric charge accumulating section for accumulating electric charges based on a gradation sequence signal to designate a luminance gradation sequence in accordance with display data, a light emission control section for generating a light emission drive current having a predetermined current value in accordance with the electric charges accumulated in the electric charge accumulating section and supplying the light emission drive current to the light emission element, a writing control section for controlling the supplying state of the electric charges based on the gradation sequence signal to the electric charge accumulating section, and a voltage control section for controlling a drive voltage for making the light emission control section perform the operation, respectively;
• a selection line in which a writing control signal for controlling the operation state of the writing control section of the each display pixel is applied;
• a hold line in which a voltage control signal for controlling the operation state of the voltage control section of the each display pixel is applied;
• and
• a data line to which the gradation sequence is supplied.,

A display having:

• a selection line;
• a hold line;
• a data line;
• a supplying voltage line;
• a hold transistor, in which a gate is connected to the hold line;
• a drive transistor having a gate and a current path, the gate of the drive transistor being connected to one end of a current path of the hold transistor, and one end of the current path of the drive transistor being connected to the supplying voltage line;
• a selection transistor having a gate and a current path, the gate of the selection transistor being connected to the selection line, one end of the current path of the selection transistor being connected to the other end of the current path of the drive transistor, and the other end of the current path of the selection transistor being connected to the data line;
• a light emission element which is connected to the other end side of the current path of the drive transistor;
• a selection driver which outputs a selection signal to the selection line;
• a hold driver which outputs a hold signal to the hold line;
• a data driver which supplies a gradation sequence signal to the data line;
• and
• a supplying voltage driver which outputs a supplying voltage to the supplying voltage line.

A display drive method of a display unit which comprises a display panel made by a plurality of display pixels and makes the each display pixel perform the light emission operation at a predetermined luminance gradation sequence by supplying a gradation sequence signal designating a luminance gradation sequence in accordance with the display data to the each display pixel, and displays desired image information on the display panel, the method comprising

• setting at least part of the plural display pixels at a selection state, and setting a first potential difference equivalent to a threshold voltage of a transistor element or a first potential difference equivalent to the minimum luminance voltage necessary for generating the light emission drive current required for making the light emission element perform the light emission operation at the minimum luminance gradation sequence between one end of a gate and one end of a current path of a transistor element for supplying a light emission drive current to a current-controlled type of a light emission element provided in the each display pixel;
• sequentially setting the display pixel for each row of the display panel at a selection state, sequentially applying a gradation sequence signal for making the light emission element of the each display pixel perform the light emission operation at a predetermined luminance gradation sequence in accordance with the display data, and setting a second potential difference in accordance with the luminance gradation sequence between a gate and one end of a current path of the transistor element;
• and
• setting at least part of the plural display elements arranged on the display panel at a no-selection state, turning on the transistor element of the each display element on the basis of the second potential difference, and individually generating the light emission drive current having a current value in accordance with the luminance gradation sequence for the each light emission element and supplying the light emission current to the each light emission element.

A light emission drive circuit for flowing a light emission drive current to make a light emission element perform light emission, comprising:

• electric charge accumulating section for accumulating electric charges on the basis of a gradation sequence signal designating a luminance gradation sequence;
• light emission control section for flowing a light emission drive current having a current value in accordance with the electric charges amount accumulated in the electric charge accumulating section;
• and
• voltage setting section for partially discharging the electric charges accumulated in the electric charge accumulating section in order for the light emission control section to set the light emission drive current at the current value.

A drive control method of a light emission drive circuit for flowing a light emission drive current to make a light emission element perform light emission, comprising:

• a first potential difference step of setting a first potential difference on the basis of a precharge voltage that is larger than the minimum luminance gradation sequence necessary for generating the light emission drive current required for making the light emission element perform the light emission operation at the minimum luminance gradation sequence or a threshold potential difference between the control terminal and one end of a current path of a drive transistor in which a current value of the light emission drive current is set by a potential difference between a control terminal and one end of the current path of the drive transistor;
• a second potential difference step of setting a second potential difference equivalent to the minimum luminance potential difference or the threshold potential difference between the control terminal and one end of the current path of the drive transistor after turning on the drive transistor on the basis of the first potential difference;
• and
• a third potential difference step of setting a third potential difference equivalent to the luminance gradation sequence between the control terminal and said one end of the current path of the drive transistor by applying a gradation sequence signal for making the light emission element to perform the light emission operation at a desired luminance gradation sequence and flowing the gradation sequence signal to the current path of the drive transistor.

A display drive method of a display unit for making light emission elements of a plurality of display pixels to perform the light emission arranged in a row direction and a column direction, comprising:

• a first potential difference step of setting the display pixel at a selection state and setting a first potential difference on the basis of a precharge voltage that is larger than the minimum luminance gradation sequence necessary for generating the light emission drive current required for making the light emission element perform the light emission operation at the minimum luminance gradation sequence or a threshold potential difference between the control terminal and one end of a current path of a drive transistor which can supply a light emission drive current to the light emission element;
• a second potential difference step of setting a second potential difference equivalent to the minimum luminance potential difference or the threshold potential difference between the control terminal and one end of the current path of the drive transistor element in a state of turning on the drive transistor on the basis of the first potential difference;
• a third potential difference step of setting a third potential difference equivalent to the luminance gradation sequence between the control terminal and said one end of the current path of the drive transistor by applying a gradation sequence signal for making the light emission element to perform the light emission operation at a desired luminance gradation sequence and flowing the gradation sequence signal to the current path of the drive transistor;
• and
• a light emission step that the drive transistor flows the light emission drive current on the basis of the gradation sequence signal to the light emission element by applying a voltage so that a potential difference between said one end and the other end of the current path of the drive transistor is saturated.

A light emission drive circuit, comprising:

• a light emission control section having a current path of flowing a light emission drive current from the current path;
• an electric charge accumulating section to accumulate electric charges in accordance with a current value of a current flowing through the light emission control section;
• a voltage setting section to supply a current of a current value that allows the light emission element to perform the light emission operation at a luminance other than the no-light luminance gradation sequence and accumulating the electric charges equivalent to the luminance gradation sequence in the electric charge accumulating section;
• and
• a gradation sequence setting section to discharge the electric charges in the electric charge accumulating section such that the light emission element is made into the no-light emission state or the electric charges such that the light emission drive current does not flow.

A display unit comprising:

• a plurality of display pixels comprising;
• a light emission element;
• and
• a light emission drive circuit having a light emission control section to apply a light emission drive current from the current path to the light emission element, an electric charge accumulating section to accumulate electric charges in accordance with the current value of the current flowing the light emission control section, and a voltage setting section to accumulate the electric charges equivalent to the luminance gradation sequence in the electric charge accumulating section, respectively;
• and
• a gradation sequence setting section to discharge the electric charges accumulated in the electric charge accumulating section so that a state of the electric charges allowing the light emission element to perform the light emission operation at a luminance gradation sequence other than a no-light emission luminance gradation sequence is changed into a state of the electric charges allowing the light emission element to perform the no-light emission state or the light emission drive current not to flow.