Tohoku Pioneer Corporation

Pioneer Corporation

Akinori Hayafuji

Katsuhiro Kanauchi

Kenichi Okuyama

Akira Moriya

A light emitting apparatus includes a transparent substrate made of glass material, for example, a first electrode layer formed on the substrate, a light emitting functional layer including organic material formed on the first electrode layer, a back surface electrode made of metallic material, for example, as a second electrode layer formed on the light emitting functional layer, and dot-shaped conductors arranged on the first electrode layer. The dot-shaped conductors made of low electric resistivity material are arranged at the first electrode layer. The combined resistance value of the transparent electrode and the plurality of dot-shaped conductors becomes lower than the resistance value of the transparent electrode alone. Therefore, voltage drop occurred at the transparent electrode can be effectively suppressed.

Light emitting apparatus with an organic electroluminescence cell

The light emitting apparatus includes a transparent substrate made of glass material, for example, a first electrode layer (that is, a transparent electrode made of ITO and the like) formed on the substrate, a light emitting functional layer including organic material formed on the first electrode layer, a back surface electrode made of metallic material, for example, as a second electrode layer formed on the light emitting functional layer, and dot-shaped conductors arranged on the first electrode layer in which the dot-shaped conductors are arranged so that a plurality of dot-shaped conductors are respectively arranged to the individual first electrode layer in a state that the dot-shaped conductors are separated from one another and further the dot-shaped conductors made of low electric resistivity material are arranged at the first electrode layer, the combined resistance value of the transparent electrode and the plurality of dot-shaped conductors becomes lower than the resistance value of the transparent electrode alone.

Treating light emitting elementsin all the display pixels in a light emitting display panel as objects, a maximum value of the forward voltages is drawn by a multi-input comparatorand a peak hold circuit. Based on the maximum value of the forward voltages, a voltage boost circuitswitching operates a power FET to supply a boosted output by this operation to a constant current circuitas the operational voltage VH. In the case where the maximum value of the forward voltages increases due to trouble or the like and based on this increment the operational voltage VH excessively increases, the operation of the voltage boost circuitis stopped by a control output from an analog comparatorwhich functions as voltage limiter.

Self light emitting type display device

Drive voltages corresponding to forward voltages for colors R, G, and B are supplied to display pixels for colors R, G, and B arranged on a display panel to correct disruption of a color balance due to aging and temperature dependence of EL elements. The maximum voltage among the drive voltages is detected, and a predetermined voltage is added to the maximum voltage by a charge pump or the like, so that an operation voltage of a level shifter in a gate driver is obtained. An operation signal having a level equal to that of the operation voltage is supplied to a gate of a transistor arranged in each pixel. Therefore, regardless of aging or the like, the control transistor accurately executes an ON operation at a timing for scanning to make it possible to prevent an image display from being defective.

Device for driving active matrix light-emitting display panel by controlling drive voltage

Treating light emitting elementsin all the display pixels in a light emitting display panel as objects, a maximum value of the forward voltages is drawn by a multi-input comparatorand a peak hold circuit. Based on the maximum value of the forward voltages, a voltage boost circuitswitching operates a power FET to supply a boosted output by this operation to a constant current circuitas the operational voltage VH. In the case where the maximum value of the forward voltages increases due to trouble or the like and based on this increment the operational voltage VH excessively increases, the operation of the voltage boost circuitis stopped by a control output from an analog comparatorwhich functions as a voltage limiter.

The ripple component superimposed on the drive power source Va applied to the source electrode of a light emission drive transistor Tris extracted by a ripple component extraction circuitand the ripple component is supplied to one input terminal of a voltage addition circuitA data voltage Vdata transmitted via a data line is input to the other input terminal of the voltage addition circuitAccordingly, in the voltage addition circuitthe ripple component extracted by the ripple component extraction circuitis added to the data voltage Vdata treating the data voltage Vdata as the base. Its output is supplied to a scan selection transistor designated by reference character SWas Vgate, and the transistor Tris turned on at an addressing time so that the Vgate is supplied to the gate of the light emission drive transistor TrThus, the gate-to-source voltage Vgs of the light emission drive transistor Trrepresents an approximately constant value all the time regardless of timing of addressing. Therefore, a problem that intensity change occurs for each scan line so that the display quality of an image is considerably deteriorated can be avoided.

Drive device and drive method of light emitting display panel

A clock signal in synchronization with a data writing signal, every scanning line, which is supplied from a light-emitting control circuitto a scanning driver, is supplied to an oscillatorwhich generates a reference switching signal, according to a PWM method, in a DC-DC converter. Thereby, the timing at data writing every scanning line is in synchronization with the phase of a ripple component superimposed on a driving voltage Va from the DC-DC converter. Accordingly, a problem that there is caused a state in which light-emitting intensity is different every scanning line can be solved because the same voltage Vgs between a gate and a source is supplied every scanning line to a light-emitting driving transistor Trat any time even if the ripple component by switching of the DC-DC converter is superimposed on the driving voltage Va. Thereby, a problem that the display quality of images is remarkably reduced can be prevented in a light-emitting driving operation of a display panel, wherein the operation has a configuration in which an organic EL element with a light-emitting intensity characteristic of a current dependence type, for example, is used as a pixel.

Light emitting display device and driving control method therefor

Provided are a detection element Em used for controlling a value of a drive voltage for each light emitting element constituting a display pixel, and a leakage detection circuitwhich separates the detection element Em from a current source Iwhen this detection element Em is in a leakage state. Further provided are a pseudo leakage setup meanswith which a potential of an anode terminal in the above-mentioned detection element can be set as a pseudo leakage potential which is a potential when the detection element is in the leakage state, and an operation detection meansto verify that the leakage detection circuitoperates normally when operating the above-mentioned pseudo leakage setup means

Display apparatus and method of inspecting the same

A clock signal synchronized with a data write signal for each scan line supplied from a light emission control circuitto a scan driveris supplied to an oscillatorgenerating a reference switching signal of a DC-DC converterby a PWM method via a frequency divider. Thus, even when a ripple component by a switching operation of the converter has been superimposed on a drive voltage Va, constantly the same gate-to-source voltage Vgs is supplied to a light emission drive transistor Trfor each scan line, whereby a problem that a state in which light emission intensities differ for each scan line is brought about can be resolved. Further, the duty ratio of a switching signal from a PWM circuitis detected by a detection circuitto grasp the load condition of the converter, and when the load is light, the division ratio of the frequency divideris increased to execute the switching operation at a low frequency. In this manner, the cycle (boost cycle) of the switching operation in the converter is made greater, so that a useless power loss by the switching operation in the converter can be reduced, whereby the power utilization rate of a light load time can be improved.

Light emitting display device and drive control method thereof

There is provided a device for driving a light-emitting display panel in which output limiter element is added to a DC-DC converter which associates a boosting operation. In the drive device, even though a forward voltage of a monitor element increases to operate the limiter element, predetermined display quality can be assured without considerably disrupting a color balance. On a display panel, a display region in which display pixels of R, G, and B are arranged and an arrangement region for monitor elements which monitor forward voltages of R, G, and B are formed. Output voltages obtained by the respective DC-DC converters are controlled based on the forward voltages obtained by the monitor elements. An output limiter is constituted by zener diodes to prevent converter output values from being excessive by increases in forward voltages from the monitor elements due to aging. Limiter values obtained by the zener diodes are set at different levels.

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Yonezawa, Japan

Akinori Hayafuji