Organic el display device and its control method

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Technical field to which the invention belongs]

The present invention relates to an organic EL display device using an electroluminescence (hereinafter referred to as organic EL (electroluminescence)) element of an organic material as a light emitting element (electro-optical element) of a light emitting pixel, and a control method thereof.

【0002】

[Conventional technology]

Flat panel displays are flat, have no depth, and are lightweight, and are expected to be devices that will support the multimedia era in the future. Typical flat panel displays include liquid crystal displays and organic EL displays. Currently, the most popular flat panel display is the liquid crystal display. However, there are some problems with this liquid crystal display that hinder high image quality.

【0003】

That is, since a conventional liquid crystal display requires a backlight, it is necessary to increase the emission brightness in order to obtain high brightness. When the emission brightness is increased, the display brightness is increased, but the liquid crystal cannot completely block the light, so that the black display performance deteriorates. Further, since the maximum brightness of the liquid crystal display is defined by the backlight, the contrast is inevitably determined by the brightness of the backlight. Therefore, it is very difficult to intentionally control the contrast and brightness by a method other than the input signal, such as a display using a cathode ray tube (hereinafter referred to as CRT (cathode ray tube)).

【0004】

Further, since the liquid crystal display is a hold type display that holds the information written in the pixels for one field period, it is significantly inferior to the CRT display from the viewpoint of the image quality of the moving image display. This is because the display light of the CRT is impulse-like, whereas in the liquid crystal display, the change of the display light is in principle stepped by holding for one field period (actually, it is exponential due to the existence of the response time of the device). This is because it becomes (exponentially changed) and blurring is perceived when the video is displayed.

【0005】

On the other hand, since the organic EL display uses an organic EL element capable of obtaining a brightness of several hundred to several 10,000 nits at a driving voltage of 10 V or less as a light emitting element of the light emitting pixel, the field of view is a self-luminous type. It is promising as a next-generation flat panel display because it has features such as no angle dependence, high contrast ratio, and superior video display performance compared to hold-type displays.

【0006】

Examples of the driving method of the organic EL display include a simple (passive) matrix method and an active matrix method. In order to realize a larger display and higher definition, in the case of the simple matrix method, the light emission period of each pixel decreases as the number of scanning lines (that is, the number of pixels in the vertical direction) increases, so that each pixel instantaneously decreases. It is required that the organic EL element of the above emits light with high brightness. On the other hand, in the case of the active matrix method, since each pixel continues to emit light for a period of one frame, it is easy to increase the size and definition of the display.

【0007】

[Problems to be Solved by the Invention]

In this active matrix type organic EL display, conventionally, the driving of light emitting pixels has always been performed under constant conditions regardless of the input signal (video signal) level. Therefore, the ratio of high brightness and high contrast depending on the characteristics of the organic EL element is large, and similarly, low power consumption has to depend on the characteristics of the organic EL element. Moreover, if a high voltage is applied to the organic EL element or a large current is continuously applied to increase the brightness, the characteristics of the organic EL element tend to deteriorate and the power consumption also increases. Occurs.

【0008】

The present invention has been made in view of the above problems, and an object of the present invention is an organic EL display device capable of high contrast and low power consumption without depending on the characteristics of the organic EL element, and an organic EL display device thereof. The purpose is to provide a control method.

【0009】

[Means for solving problems]

In order to achieve the above object, in the present invention, in an organic EL display device in which organic EL elements are arranged in a matrix as light emitting pixels, the signal level of the original source signal that is the source for driving the light emitting pixels is detected. A configuration is adopted in which the light emission time of the light emitting pixel is controlled based on the detection level.

【0010】

The control based on the signal level of the original source signal is a feed-forward type control. In this feed-forward type control, since the signal level detection result can be reflected in the control of the light emission time in the next field, control with less delay can be realized. Further, since the feedforward control is based on the original source signal, the light emission time of each light emitting pixel can be controlled without being affected by the characteristics of the light emitting elements of each of R (red), G (green), and B (blue).

【0011】

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

【0012】

[First Embodiment] FIG. 1 is a block diagram showing an outline of a configuration of an organic EL display device according to a first embodiment of the present invention.

【0013】

As is clear from FIG. 1, the organic EL display device according to the present embodiment includes an organic EL panel 11, an RGB matrix circuit 12, a resolution conversion circuit 13, an A / D conversion circuit 14, a panel control circuit 15, and a signal synthesis circuit 16. , LPF (low-pass filter) 17, A / D conversion circuit 18, and total data detection circuit 19. It is also possible to make the total data detection circuit 19 into an IC together with the panel control circuit 15 so that the panel control circuit 15 has the function of the total data detection circuit 19.

【0014】

The organic EL panel 11 has a configuration in which a large number of pixel circuits including organic EL elements are arranged in a matrix on a substrate such as transparent glass. Specifically, a first electrode (for example, an anode) made of a transparent conductive film is formed on a substrate, and a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer are sequentially deposited on the first electrode (for example, an anode). As a result, an organic layer is formed, and a second electrode (for example, a cathode) made of a metal having a low work function is further formed on the organic layer to form an organic EL element.

【0015】

In this organic EL element, by applying a DC voltage between the first electrode and the second electrode, holes pass through the hole transport layer from the first electrode (anode), and electrons are second. Each is injected into the light emitting layer from the electrode (cathode) via the electron transport layer, and the injected positive and negative carriers bring the fluorescent molecules in the light emitting layer into an excited state so that light emission can be obtained in the relaxation process of the excited molecules. It has become.

【0016】

In a pixel circuit including an organic EL element, a thin film transistor (TFT) is generally used as an active element for driving the organic EL element. The pixel circuit usually has a plurality of TFTs and also has a capacitor for holding pixel information (luminance information).

【0017】

Further, on the substrate of the organic EL panel 11, the number of gate lines corresponding to the number of vertical pixels and the number of data lines corresponding to the number of horizontal pixels are wired in a matrix, and the organic EL element is placed at the intersection thereof. The including pixel circuit will be arranged. Then, these pixel circuits are sequentially selected row by row by the vertical scanning circuit, and luminance information is given to the selected pixel circuits for one row from the panel control circuit 15 through data lines for each column. .. In each of the selected pixel circuits for one line, the organic EL element is driven by selectively giving luminance information from the data line through the driving TFT.

【0018】

Luminance signals Y and color difference signals Cb and Cr are input to the RGB matrix circuit 12. The RGB matrix circuit 12 converts the luminance signal Y and the color difference signals Cb and Cr into analog RGB signals. This analog RGB signal is processed by the resolution conversion circuit 13 for resolution conversion to match the resolution (number of horizontal / vertical dots) of the organic EL panel 11, and then the A / D conversion circuit 14 performs, for example, 8-bit digital. It is converted into an RGB signal and supplied to the panel control circuit 15.

【0019】

The analog RGB signal is also supplied to the signal synthesis circuit 16 as an original source signal that is a source for driving the light emitting pixels. The signal synthesis circuit 16 performs a process of synthesizing an analog RGB signal in order to detect the overall signal level of the original source signal. In this signal synthesis circuit 16, for example, as shown in FIG. 1, transistors Q11, Q12, Q13 in which each collector is connected to the power supply VCC and an analog RGB signal is given to each base, and these transistors Q11, Q12, Q13. Diodes R11, R12, R13 connected between each emitter and ground, and diodes D11, D12, with each anode connected to each emitter of transistors Q11, Q12, Q13 and each cathode connected in common. It has a configuration with D13.

【0020】

The analog signal synthesized by the signal synthesis circuit 16 is supplied to the A / D conversion circuit 18 through the LPF17. The LPF17 removes noise components and high-frequency components contained in the analog signal to set the optimum signal band for data detection in the subsequent stage, for example, about several hundred Hz. As shown in FIG. 1, the LPF17 includes a buffer portion consisting of a resistor R14 and a transistor Q14 connected in series between the power supply VCC and ground, a resistor R15 having one end connected to the emitter of the transistor Q14, and the resistor R15. It is composed of a filter portion consisting of a capacitor C11 connected between the other end of the resistor R15 and the ground.

【0021】

The analog signal that has passed through the LPF 17 is converted into, for example, 4-bit digital signal data by the A / D conversion circuit 18. Here, the digital signal data does not need to be highly accurate because the data can be adjusted in the panel control circuit 15 in the subsequent stage. Further, as will be described later, since the sampling frequency in the A / D conversion circuit 18 is as low as about 1 kHz, if the 4-bit A / D conversion circuit 18 is used, the A / D conversion circuit is used by using a general-purpose operational amplifier. Can be constructed at low cost.

【0022】

In the A / D conversion circuit 18, for example, as shown in FIG. 2, sampling is performed four times within one horizontal scanning period (1H), and sampling in the horizontal scanning direction is repeatedly executed at, for example, four points in the vertical scanning direction. As a result, as shown in Fig. 3, sampling is performed 16 times within the data for one field (one screen). However, the sampling method in the A / D conversion circuit 18, that is, sampling 16 times in one field period is an example, and the number of samplings can be increased or decreased. By increasing the number of samplings, finer control can be performed.

【0023】

The sampling data in the A / D conversion circuit 18 is supplied to the total data detection circuit 19. The total data detection circuit 19 latches the sampled data in the A / D conversion circuit 18 and takes the sum of the data for 16 points in one field between the vertical synchronization pulses (V-Sync), that is, one field (V-Sync). The total data for one screen) is detected, and the detected total data is supplied to the panel control circuit 15.

【0024】

The panel control circuit 15 sequentially scans each light emitting pixel of the organic EL panel 11 line by line, and a digital RGB signal supplied from the A / D conversion circuit 14 to each RGB organic EL element of the selected light emitting pixel. In addition to controlling the drive current to flow according to the signal level of, the light emission time of the organic EL element is controlled based on the total data for one field supplied from the total data detection circuit 19.

【0025】

Here, the control of the light emission time based on the total data for one field will be specifically described.

【0026】

The panel control circuit 15 has a built-in look-up table (LUT) 15A for converting the total data for one field into the light emission time, and by referring to this look-up table 15A, the total data for one field can be obtained. Determine the emission time of the corresponding organic EL element. For the lookup table 15A, in Fig. 4, for example, as shown by the solid line, the standard setting is such that a linear linear emission time (duty ratio) can be obtained for the input data (4 bits x 16 samplings in this example). It is supposed to be.

【0027】

In the present embodiment, the duty ratio of the light emission time is 50% when the total data is the minimum, and the duty ratio of the light emission time is 25% when the total data is the maximum. In this way, by setting the relationship between the total data for one field and the light emission time to be linear and linear, the maximum peak brightness of 300 nits / all-white input brightness is not impaired and the brightness changes are not uncomfortable. The specification of 150 nit can be satisfied.

【0028】

In the present embodiment, the lookup table 15A is set as a standard so that a linear linear emission time (duty ratio) can be obtained with respect to the input data, but the value is set according to the preference of image quality and the input source. Can be set to the characteristics shown by the dotted curve in FIG.

【0029】

Next, the circuit operation of the organic EL display device according to the first embodiment of the above configuration will be described.

【0030】

The brightness signal Y and the color difference signals Cb and Cr are converted into analog RGB signals by the RGB matrix circuit 12, then converted into resolution by the resolution conversion circuit 13, and converted into digital RGB signals by the A / D conversion circuit 14 for panel control. It is supplied to the circuit 15, synthesized by the signal synthesis circuit 16, the noise component and the high frequency component are removed by the LPF 17, and converted into digital signal data by the A / D conversion circuit 18 and supplied to the total data detection circuit 19. ..

【0031】

The total data detection circuit 19 detects the total data for one field (one screen) by latching the data obtained by sampling in the A / D conversion circuit 18 and taking the sum of the data for, for example, 16 points. Then, the detected total data is supplied to the panel control circuit 15.

【0032】

The panel control circuit 15 scans each light emitting pixel of the organic EL panel 11 in order in line units, and drives and controls each of the RGB organic EL elements of the selected light emitting pixel with a drive current corresponding to the signal level of the digital RGB signal. At the same time, the light emission time of the organic EL element is controlled with reference to the lookup table 15A based on the total data for one field supplied from the total data detection circuit 19.

【0033】

As described above, in an organic EL display device in which light emitting pixels including an organic EL element are arranged in a matrix, the signal level of an analog video signal which is an original source signal is detected, and the organic EL element is based on the detection level. By controlling the light emission time of the device and appropriately combining the light emission period / non-light emission period, it is possible to achieve both the contradictory conditions of high contrast and low power consumption without depending on the characteristics of the organic EL element. It becomes.

【0034】

That is, when shining a small area, a long light emitting period is set and the organic EL element is made to emit light with high brightness, so that an image having a high impact with a sense of contrast can be displayed. Further, in a bright screen having a large area, by suppressing the brightness, it is possible to suppress the deterioration of the organic EL element due to the heat generation of the organic EL element and the driving current without impairing the image quality. Therefore, this organic EL display device. The life of the product can be extended.

【0035】

In particular, the control based on the signal level of the analog video signal is a feed-forward type control, and the detection result of the total data for one field can be reflected in the control of the light emission time in the next field, so control with less delay is realized. it can. Specifically, since the total detected data is reflected in the next field, the response time delay is only one field, and when the vertical scanning frequency is, for example, 60 Hz, it is only 16.7 msec.

【0036】

Incidentally, in a general television receiver using a CRT, ABL (Automatic Brightness Limiter) control technology is used. This ABL control is originally a technology used for the purpose of expanding the beam spot diameter due to overcurrent and preventing the problematic load of horizontal deflection, but at the same time, it also plays a major role in increasing contrast and reducing power consumption. ..

【0037】

However, in this ABL control, the total current flowing through the cathode is detected and the beam current is controlled by feedback control, so that the stabilization time in the transient response takes about 200 msec. As a result, in a sudden change from a bright scene to a dark scene, or vice versa, a momentary response delay can be visually recognized, which makes the person feel a little uncomfortable.

【0038】

On the other hand, in the organic EL display device according to the present embodiment, as described above, the response delay is only about 16.7 msec due to the feedforward control, and this response speed is a general liquid crystal display device ( It is also the response speed of the LCD), and you will not feel any discomfort visually.

【0039】

Moreover, since the feedforward control is based on the original source signal, the light emission time can be controlled without being affected by the characteristics of each of the RGB organic EL elements. That is, since the luminous efficiency of the organic EL element is different in RGB, in the case of feedback control, if the luminous efficiency is extremely poor for a certain color, the average luminous amount cannot be obtained, so accurate control is performed. You will not be able to do it. On the other hand, in the case of feedforward control, by performing control based on the original source signal, the luminous efficiency of each organic EL element is not affected, so that the luminous time can be controlled accurately. become.

【0040】

In the above embodiment, the analog RGB signal is used as the original source signal, so that the analog RGB signal is synthesized by the signal synthesis circuit 16 and then input to the LPF17. However, the composite video signal is used as the original source signal. And component Y signals can also be used. In this case, the signal synthesis circuit 16 becomes unnecessary, and the composite video signal or the component Y signal (luminance signal Y of the color difference input) may be directly input to the LPF17. However, it is necessary to change the constant of LPF17 (resistance value of resistor R15, capacitance value of capacitor C11, etc.) according to the input signal.

【0041】

[Second Embodiment] FIG. 5 is a block diagram showing an outline of a configuration of an organic EL display device according to a second embodiment of the present invention.

【0042】

As is clear from FIG. 5, the organic EL display device according to the present embodiment includes an organic EL panel 21, a resolution conversion circuit 22, an A / D conversion circuit 23, a panel control circuit 24, a signal synthesis circuit 25, a sampling circuit 26, and the like. It has a configuration having a total data detection circuit 27. The signal synthesis circuit 25, the sampling circuit 26, and the total data detection circuit 27 are integrated with the panel control circuit 24 into an IC, and the panel control circuit 24 is provided with the functions of the adder circuit 25, the sampling circuit 26, and the total data detection circuit 27. It is also possible to have it.

【0043】

Similar to the organic EL panel 11 in the organic EL display device according to the first embodiment, the organic EL panel 21 has a configuration in which a large number of pixel circuits including organic EL elements are arranged in a matrix on a substrate such as transparent glass. ing. An analog video signal is input to the resolution conversion circuit 22. This analog video signal is processed by the resolution conversion circuit 22 for resolution conversion to match the resolution of the organic EL panel 21, and then converted into, for example, an 8-bit digital RGB signal by the A / D conversion circuit 23. It is supplied to the control circuit 24.

【0044】

The 8-bit digital RGB signal is also supplied to the signal synthesis circuit 25 as an original source signal that is the source for driving the light emitting pixels. The signal synthesis circuit 25 performs a process of synthesizing (adding) the upper 4 bits of an 8-bit digital RGB signal. The data obtained by synthesizing in the signal synthesis circuit 25 is sampled in the sampling circuit 26 16 times between vertical synchronization pulses (V-Sync), that is, in one field, as in the case of the first embodiment. Will be done.

【0045】

However, the sampling method in the sampling circuit 26, that is, sampling 16 times in one field period is an example, and the number of samplings can be increased or decreased. By increasing the number of samplings, finer control can be performed. If 8-bit signal data is sampled as it is, the amount of data will be enormous. Therefore, in the present embodiment, only the upper 4 bits are sampled by combining only the upper 4 bits in advance with the signal synthesis circuit 25. It is supposed to be.

【0046】

Further, in the case of digital data, since optimum filtering is not performed, it is necessary to calculate the average in the widest possible range in the vicinity of the pixel points to be sampled. Here, the resolution conversion circuit 13 generally incorporates, for example, an interpolation function using four neighboring points, that is, a function of generating data that does not originally exist using the data of the four neighboring points. By using the interpolation function with four nearby points, the average in the widest possible range near the pixel points to be sampled can be calculated.

【0047】

The data sampled by the sampling circuit 26 is supplied to the total data detection circuit 27. The total data detection circuit 27 detects the total data for one field (one screen) by latching the input sampling data and summing the data for 16 points, as in the case of the first embodiment. Then, the detected total data is supplied to the panel control circuit 24.

【0048】

Similar to the case of the first embodiment, the panel control circuit 24 has a built-in look-up table (LUT) 24A for converting the total data for one field into light emission time, and each light emission of the organic EL panel 21. The pixels are scanned in sequence row by row, and each of the RGB organic EL elements of the selected light emitting pixel is driven and controlled by the drive current according to the signal level of the digital RGB signal, and is supplied from the total data detection circuit 271. Based on the total data for the fields, the emission time of the organic EL element is controlled with reference to the look-up table 24A.

【0049】

As described above, since the organic EL display device according to the second embodiment also adopts the feed-forward type control that controls the light emission time based on the signal level of the digital RGB signal which is the original source signal, the first embodiment is performed. It is possible to obtain the same action and effect as in the case of the organic EL display device according to the form. In addition to this, since the digital RGB signal input to the panel control circuit 15 is used as the original source signal, control is possible regardless of the type of signal input to the display device.

【0050】

[Third Embodiment] FIG. 6 is a block diagram showing an outline of a configuration of an organic EL display device according to a third embodiment of the present invention.

【0051】

As is clear from FIG. 6, the organic EL display device according to the present embodiment includes an organic EL panel 31, a resolution conversion circuit 32, an A / D conversion circuit 33, a panel control circuit 34, a write current detection circuit 35, an LPF36, and A. It is configured to have a / D conversion circuit 37 and a total data detection circuit 38. It is also possible to make the total data detection circuit 38 into an IC together with the panel control circuit 34 so that the panel control circuit 34 has the function of the total data detection circuit 38.

【0052】

Similar to the organic EL panel 11 in the organic EL display device according to the first embodiment, the organic EL panel 31 has a configuration in which a large number of pixel circuits including organic EL elements are arranged in a matrix on a substrate such as transparent glass. ing. FIG. 7 shows an example of a specific configuration of the pixel circuit.

【0053】

In FIG. 7, for example, the cathode of the organic EL element 41 is commonly connected line by line between pixels. An EL drive FET 42 that allows a drive current to flow through the organic EL element 41 is connected between the anode of the organic EL element 41 and the power supply VCC. A capacitor 43 is connected between the gate of the EL drive FET 42 and the power supply VCC. The capacitor 43 holds a voltage (luminance information) for driving the EL drive FET 42.

【0054】

A data writing FET 44 and a vertical selection FET 45 are connected in series between the power supply VCC and the data line 51. The data writing FET 44 has a diode connection configuration in which a gate and a drain are commonly connected, and converts a write current supplied through the data line 51 into a voltage. Further, the data writing FET 44 forms a current mirror circuit together with the driving FET 42 by connecting the gate / drain to the gate of the EL driving FET 42 via the emission time control FET 46.

【0055】

The gate of the vertical selection FET 45 is connected to the vertical selection line 52 row by row, and pixels are selected row by row by applying a vertical scanning pulse from the panel control circuit 34 via the selection line 52. The gate of the light emission time control FET 46 is connected to the light emission time control line 53 line by line, and is turned on (conducting) while the light emission time setting signal is given from the panel control circuit 34 via the control line 53. The light emission time of the organic EL element 41 is controlled by the state.

【0056】

As described above, the pixel circuit 40 is configured. Then, the pixel circuits 40 are arranged in a matrix to form the organic EL panel 31. Data is supplied to the data line 51 from the sample hold circuit 54 via the horizontal selection FET 55 in the form of an electric current. The horizontal selection FET 55 sequentially supplies data to the pixel circuit 40 by sequentially applying horizontal scanning pulses from the sample hold circuit 54 to the gate within one horizontal scanning period.

【0057】

Again, in FIG. 6, an analog video signal is input to the resolution conversion circuit 32. This analog video signal is processed by the resolution conversion circuit 32 for resolution conversion to match the resolution of the organic EL panel 31, and then converted into, for example, an 8-bit digital RGB signal by the A / D conversion circuit 33. It is supplied to the control circuit 34.

【0058】

The write current detection circuit 35 is composed of a current detection resistor 35A connected between each of the data lines 51 and the ground on the organic EL panel 31, and detects the write current flowing through the data write FET 44 of each pixel circuit 40. And convert it to voltage. The detection voltage corresponding to this write current is supplied to the LPF36 outside the panel as an original source signal that is the source for driving the light emitting pixel. The LPF36 removes the high frequency component in the detection voltage and supplies it to the A / D conversion circuit 37.

【0059】

In the A / D conversion circuit 37, as in the case of the first embodiment, sampling is performed four times within one horizontal scanning period, and sampling in the horizontal scanning direction is repeatedly executed at, for example, four points in the vertical scanning direction. Then, the data for one field (one screen) is sampled 16 times. However, the sampling method in this A / D conversion circuit 37, that is, sampling 16 times in one field period is an example, and the number of samplings can be increased or decreased. By increasing the number of samplings, finer control can be performed.

【0060】

The sampling data in the A / D conversion circuit 37 is supplied to the total data detection circuit 38. The total data detection circuit 38 latches the sampled data in the A / D conversion circuit 37 and takes the sum of the data for 16 points in one field between the vertical synchronization pulses (V-Sync), that is, one field (V-Sync). The total pixel data write current for one screen) is detected, and the detected total pixel data write current is supplied to the panel control circuit 34.

【0061】

The panel control circuit 34 sequentially scans each light emitting pixel of the organic EL panel 31 line by line, and a digital RGB signal supplied from the A / D conversion circuit 33 to each RGB organic EL element of the selected light emitting pixel. In addition to controlling the drive current according to the signal level of the above, the light emission time of the organic EL element 41 is controlled based on the total data for one field supplied from the total data detection circuit 38.

【0062】

As described above, since the organic EL display device according to the third embodiment also adopts the feed-forward type control that controls the light emission time based on the pixel data writing current which is the original source signal, the first embodiment is used. As in the case of the organic EL display device, in addition to being able to achieve both the contradictory conditions of high contrast and low power consumption without depending on the characteristics of the organic EL element, delay-free control is realized. In addition, the light emission time can be controlled without being affected by characteristics such as the light emission efficiency of each of the RGB organic EL elements.

【0063】

[Effect of the invention]

As described above, according to the present invention, the organic EL element by detecting the signal level of the original source signal that is the source for driving the light emitting pixel and controlling the light emitting time of the light emitting pixel based on the detection level. In addition to being able to achieve high contrast and low power consumption without depending on the characteristics of, the feed-forward type control enables delay-free control and RGB light emitting elements. The light emission time of each light emission pixel can be controlled without being affected by characteristics such as light emission efficiency.

[Simple explanation of drawings]

[Figure 1]

It is a block diagram which shows the outline of the structure of the organic EL display device which concerns on 1st Embodiment of this invention.

[Figure 2]

1 This is a timing chart showing the sampling relationship within the horizontal scanning period.

[Fig. 3]

It is a timing chart showing the state of sampling at 16 points in one field.

[Fig. 4]

It is an input / output characteristic diagram which shows the relationship of the light emission time (duty ratio) with respect to the input data of a look-up table (LUT).

[Fig. 5]

It is a block diagram which shows the outline of the structure of the organic EL display device which concerns on 2nd Embodiment of this invention.

[Fig. 6]

It is a block diagram which shows the outline of the structure of the organic EL display device which concerns on 3rd Embodiment of this invention.

[Fig. 7]

It is a circuit diagram which shows an example of the specific structure of a pixel circuit.

[Explanation of symbols]

11,21,31 ... Organic EL panel, 12 ... RGB matrix circuit, 13,22,32 ... Resolution conversion circuit, 15,24,34 ... Panel control circuit, 16,25 ... Signal synthesis circuit, 17,36 ... low pass filter, 19,27,38 ... total data detection circuit, 26 ... sampling circuit, 35 ... write current detection circuit, 40 ... pixel circuit, 41 ... organic EL element