Abstract: One frame (period) is divided into a plurality of sub-frames including a lighting period and a non-lighting period for a pixel, and gradation control is carried out by selecting the above-mentioned sub-frames and by summing the lighting periods of the pixel within one frame period. In addition, proportions of the above-mentioned lighting period and the non-lighting period for every sub-frame are changed so as to perform selection operation of a gamma value of a gradation characteristic. A sum of the lighting periods within one frame period of the pixel at the time of setting the maximum gradation by way of the above-mentioned gradation control is set to be the same at the time of selecting any gamma value selected by the above-mentioned gamma value selection operation. Thus, it is possible to control luminosity changes generated when switching gamma values of gradation characteristics, especially at the time of the maximum gradation, and reduce degrees of a user's sense of incongruity.

Abstract: In a drive device for an active type light emitting display panel which can apply a reverse bias voltage to an EL element, in order to be able to compensate deterioration in light-emitting efficiency of the EL element accompanied by applying of the reverse bias voltage and the like, one pixel 10 is composed of a controlling TFT (Tr1), the driving TFT (Tr2), a capacitor C1, and the EL element E1. Switching switches SW1, SW2 mutually enables a supplying state of a forward current to the EL element E1 and an applying state of the reverse bias voltage to be selected. In one control form according to the present invention, when the applying state of the reverse bias voltage shifts to the supplying state of the forward current, by switching one switch first, the anode and cathode of the EL element E1 are made to the same electrical potential to allow electrical charges to be discharged.

Abstract: A constant electric current value supplied to a monitoring element Ex is controlled based on dimmer information, during which time a forward voltage Vf is produced and acquired by a peak hold circuit 9. Based on output of the peak hold circuit 9, an output voltage VH of a DC-DC converter 5 is controlled, and provided as a drive voltage for a display panel.

Abstract: A drive device of a self light emitting display panel which is equipped with a plurality of light emitting elements arranged at intersection positions between a plurality of data lines and plurality of scan lines comprises a first gradation control means (21, 24, 25, 26, 30) for time-dividing one frame period into N (N is a positive integer) subframe periods to set gradation display by the total of one or plural lighting control periods wherein where a and b are integers which satisfy 0<a<b<N, at an intensity level a, in addition to subframe periods during which lighting is performed at an intensity level a-1, the first gradation control means allows other one subframe period to be lit, and at an intensity level b, in addition to subframe periods during which lighting is performed at an intensity level b-1, the first gradation control means allows at least other two or more subframe periods to be lit.

Abstract: A drive device of a self light emitting display panel which is equipped with a plurality of organic EL elements 14 arranged at intersection positions between a plurality of data lines and plurality of scan lines comprises a first gradation control means for time-dividing a frame period into a plurality of subframe periods and setting gradation of each pixel by the sum of lighting periods of one or plural subframe periods, a second gradation control means for treating mutually adjacent plural pixels as a group and performing dither processing on a per group basis, and a reverse bias voltage applying means 27 for applying a reverse bias voltage to the light emitting elements. A subframe period to be a non-lighting period is provided in the plural subframes so that during this period the reverse bias voltage is applied to all light emitting elements by the reverse bias voltage applying means.

Abstract: A clock signal in synchronization with a data writing signal, every scanning line, which is supplied from a light-emitting control circuit 4 to a scanning driver 6, is supplied to an oscillator 12 which generates a reference switching signal, according to a PWM method, in a DC-DC converter 8. 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 8. 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 Tr2 at any time even if the ripple component by switching of the DC-DC converter is superimposed on the driving voltage Va.

Abstract: The present invention is to provide a display device which efficiently drives light emitting display pixels and which can restrain an excessive increment of an operational voltage outputted from a power supply circuit due to trouble of the circuit or the like. Treating light emitting elements 2 in 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 comparator 3a and a peak hold circuit 3b. Based on the maximum value of the forward voltages, a voltage boost circuit 6 switching operates a power FET to supply a boosted output by this operation to a constant current circuit 1 as 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 circuit 6 is stopped by a control output from an analog comparator 7a which functions as a voltage limiter.

Abstract: The present invention is to provide a drive device which can efficiently collect electrical charges accumulated in the parasitic capacitances of light emitting elements so as to reduce power consumption in a light emitting display panel. Control is performed in such a manner that respective EL elements which become lighting objects are allowed to sequentially begin to be lit in response to a length of time determined in accordance with gradation control during a constant current drive period and that extinguishing timing of the respective light emitting elements which have received lighting control corresponds to the end of the lighting drive period. Thus, lighting time of the EL elements during the constant current drive period is controlled in accordance with gradation, and multi-gradation expression can be realized for each pixel.

Abstract: In the case where time gradation is implemented, there is provided a drive method for a passive drive type light emitting display panel by which an excellent gradation expression can be realized without subdividing intensity resolution so much. Provided is an intensity increase period in which the light emission intensity of a light emitting element is gradually increased allowing the light emission intensity to reach a constant intensity state within a predetermined period from a scan start in one scan period or an intensity decrease period in which the light emission intensity of the light emitting element is gradually decreased from the constant intensity state within a predetermined period which is immediately before the completion of the scan period.

Abstract: Power saving is more realized when a partial display is executed in active matrix type EL display elements. When the partial display is executed, a scan driver 2 repeatedly scans all the scan lines as executed ordinarily. In contrast, when a scan shifts from a display region to a non-display region, black display data is captured by a shift resister 1a in a data driver 1 for one horizontal period and latched by a latch circuit 1b. Then, while the non-display region is being scanned, the drive of the data driver 1 is stopped. Accordingly, in the scan of the non-display region, a non-display state is achieved by the black display data latched by the latch circuit 1b. Low power consumption can be realized because the drive of the data driver 1 operating at a high speed is stopped while the non-display region is being scanned.

Abstract: In a drive device for an active type light emitting display panel which can apply a reverse bias voltage to an EL element, in order to be able to compensate deterioration in light-emitting efficiency of the EL element accompanied by applying of the reverse bias voltage and the like, one pixel 10 is composed of a controlling TFT (Tr1), the driving TFT (Tr2), a capacitor C1, and the EL element E1. Switching switches SW1, SW2 mutually enables a supplying state of a forward current to the EL element E1 and an applying state of the reverse bias voltage to be selected. In one control form according to the present invention, when the applying state of the reverse bias voltage shifts to the supplying state of the forward current, by switching one switch first, the anode and cathode of the EL element E1 are made to the same electrical potential to allow electrical charges to be discharged.

Abstract: Power saving is more realized when a partial display is executed in active matrix type EL display elements.