A pixel includes a pixel circuit and an organic light emitting diode. The pixel circuit has first, second, third, and fourth transistors. The first transistor controls an amount of current flowing from a first driving power supply coupled to a first node to a second driving power supply through the organic light emitting diode. The turns on when a scan signal is supplied to a first scan line. The third transistor turns on when a scan signal is supplied to a second scan line. The fourth transistor turns on when a scan signal is supplied to a third scan line. The first transistor is a p-type Low Temperature Poly-Silicon thin film transistor and the third transistor and the fourth transistor are n-type oxide semiconductor thin film transistors.

Disclosed is a display device, including: a substrate including a pixel area and a peripheral area; pixels provided in the pixel area as a plurality of pixel rows and a plurality of pixel columns; data lines configured to provide a data signal; scan lines configured to provide a scan signal; first power lines configured to provide a power source to the pixel columns; and a second power line connected to the first power lines and disposed in the peripheral area. A scan line connected to an i.sup.th pixel row may apply a scan signal to the i.sup.th pixel row, and a branched line branched from the scan line may apply an initialization signal to a k.sup.th pixel row (k≠i). A branched point of the scan line is disposed between a pixel most adjacent to the second power line of the i.sup.th pixel row and the second power line.

A pixel includes a plurality of transistors and an organic light emitting diode. The transistors include a first transistor to control an amount of current flowing to the organic light emitting diode. Additional transistors are connected to the first transistor or the organic light emitting diode. The first transistor is a Low Temperature Poly-Silicon (LTPS) thin film transistor. One or more of the other transistors are oxide semiconductor transistors.

A method of testing a display panel including a pixel coupled to first, second, and third power lines, a data line, scan lines, an emission control line, and a test line, the method includes: applying a first power supply voltage to the first power line; applying a test voltage having a turn-on voltage level to the second power line; applying a scan signal having a turn-on voltage level sequentially to the scan lines and an emission control signal having a turn-on voltage level to the emission control line; applying a gate signal to the test line to turn on a test transistor coupled between two electrode of a light emitting element included in the pixel; measuring a sensing voltage output through the data line; and determining whether the pixel is defective, based on a voltage level of the measured sensing voltage.

A display device includes at least a first luminance range and a second luminance range which includes a luminance different from the first luminance range. In a boundary area of a second dimming range corresponding to the second luminance range and which is adjacent to a first dimming range corresponding to the first luminance range, a reference luminance emitted from a pixel is maintained as a first constant luminance value, and an off-duty number, which is the number of periods in which the pixel is turned off during one frame, is gradually increased by an emission control signal.

A pixel circuit, is provided, including: a light-emitting element, a driving circuit, a data writing circuit, an on-off control circuit, a first initialization circuit and an energy storage circuit; the data writing circuit writes a data voltage into a third node under control of a first gate driving signal; the on-off control circuit controls communication between a first node and the third node under the control of the first gate driving signal; the first initialization circuit controls writing an initialization voltage into the first node under the control of the first gate driving signal; and a type of a transistor included in the first initialization circuit is different from a type of a driving transistor included in the driving circuit, and a type of a transistor included in the data writing circuit is different from the type of the driving transistor of the driving circuit.

An electro-optical device includes one or more control lines that include a scanning line, a data line and a pixel circuit. The pixel circuit has a drive transistor, a write-in transistor with a gate which is electrically connected to the scanning line, a light-emitting element that emits light at a brightness that depends on the size of a current that is supplied through the drive transistor, and a control line which overlaps the gate of the drive transistor when viewed from a direction that is perpendicular to a surface of a substrate on which the pixel circuit is formed is included in the one or more control lines.

A display substrate and a display apparatus are disclosed. The display substrate includes a display region and a peripheral region, the peripheral region includes a circuit region, and the display region includes a plurality of sub-pixels, a plurality of data lines extending along a first direction and a plurality of gate lines extending along a second direction crossing the first direction. The circuit region includes a plurality of driving unit groups. The circuit region includes a first sub-region and a second sub-region that are opposite to each other at two sides of the display region along the first direction, the first sub-region includes a plurality of multiplexing unit groups and the second sub-region includes a plurality of test unit groups.

A light emitting element includes a first electrode, a second electrode, and a light emission layer interposed between the first electrode and the second electrode, where an emission efficiency of the light emission layer varies based on a voltage applied to at least one selected from the first electrode and the second electrode.

A display device is disclosed that may include a first active layer disposed on a substrate, a scan line disposed on the first active layer, extending in a first direction and including a first protruding portion protruding in a second direction crossing the first direction, a first compensation control line disposed on the first active layer, extending in the first direction and spaced apart from the scan line in the second direction, and a second active layer disposed on the scan line and the first compensation control line, overlapping the scan line and the first compensation control line and including a second protruding portion protruding in the first direction. The first protruding portion may be positioned outside the second active layer in the first direction in a plan view.