JP4735763B2 - Image display device and driving method thereof - Google Patents

Description

  The present invention relates to an image display apparatus used for car audio equipment, portable equipment, and the like and a driving method thereof.

  When an image display device in which light emitting elements such as organic EL elements are arranged in a matrix is driven by line-sequential driving, it is necessary to discharge charges accumulated in the elements, or the cathode potential varies depending on the anode potential. As a result, a charge / discharge phenomenon of the light emitting element may occur. For this reason, there was a problem that sufficient image quality could not be obtained. Therefore, in order to avoid this problem, for example, as described in Japanese Patent Application No. 2003-12195, the resistance of the scan driver is lowered, or the timing for inputting data to the data electrode is shifted in time, thereby charging and discharging the light emitting element. It has been proposed by the present applicant to shorten the time and suppress the occurrence of the charge / discharge phenomenon. As a result, the light emitting element can obtain a sufficient gradation, and a reduction in image quality can be suppressed.

  However, there is a problem that the cost of the scanning driver increases in order to reduce the resistance of the scanning driver. Further, it has been found that there is a limit on the number of gradations when the timing for inputting data to the data electrode is shifted with respect to time. In view of the above, the present invention provides a driving method of an image display device capable of ensuring a sufficient number of gradations when the image display device is line-sequentially driven, and has a sufficient number of gradations to ensure sufficient image quality. This realizes an image display apparatus capable of realizing the above.

The present invention is realized by the following configuration.
(1) A line-sequential driving method of an image display device having an organic electroluminescent element in which scan electrodes and data electrodes are arranged in a matrix on a substrate, wherein non-selected scan electrodes are connected to a positive potential, The selected scan electrode is connected to the Gnd potential, the scan electrode is driven line-sequentially, the non-selected scan electrode is connected to a positive potential, and the selected scan electrode is connected to the Gnd potential. Within a certain period, the data electrode is connected to a constant current source, and after the data electrode is disconnected from the constant current source, after being in a high impedance state or a floating state for a certain period of time, A driving method characterized by connecting.

(2) An image display device having scan electrodes and data electrodes arranged in a matrix on a substrate, an organic electroluminescent element formed at an intersection of the scan electrodes and the data electrodes, and a display control unit, The display control unit drives the scan electrodes line-sequentially via a scan electrode drive unit and drives the data electrodes via a data electrode drive unit, and the display control unit adds non-selected scan electrodes. And the selected scan electrode is connected to the Gnd potential, the non-selected scan electrode is connected to the positive potential, and the selected scan electrode is connected to the Gnd potential. The data electrode is connected to a constant current source, and after the data electrode is disconnected from the constant current source, it is in a high impedance state or a floating state for a certain period of time. An image display apparatus characterized by connecting to the Gnd potential.

  The present invention relates to a driving method for a line sequential image display apparatus. Then, a concrete solution means is described. In general, in the case of line-sequential driving, when grayscale data is input to the data electrode and the grayscale data is turned off, the next scanning electrode is normally selected, and the data electrode is Gnd during the period until the grayscale data is input to the data electrode. It remains connected to the potential. In this case, if the time required for charging and discharging the charge accumulated in the light emitting element that does not contribute to light emission is long, high gradation display cannot be realized. Therefore, the charge / discharge time of the light emitting element is shortened by shortening the charge / discharge time of the light emitting element that does not contribute to light emission. That is, high gradation expression is realized by complementing the charge required for the discharge in a short time. Specifically, when the data input to the data electrode is turned off, the potential of the data electrode is connected to the Gnd potential for a certain time. The time to connect to the Gnd potential is longer than the time to recover the cathode of the light emitting element connected to the non-selected scan electrode from the Gnd potential to (scanning electrode power supply voltage−light emission threshold potential). The data electrode is held in a high impedance state or a floating state after a certain time in this period. Then, after the complementation of the charge of the light emitting elements is completed and the light emission of all the light emitting elements is completed, it is connected to the Gnd potential.

  Another means of the present invention will be described. In general, in the case of line-sequential driving, when grayscale data is input to the data electrode and the grayscale data is turned off, the next scanning electrode is normally selected, and the data electrode is Gnd during the period until the grayscale data is input to the data electrode. It remains connected to the potential. In this case, if the time required for charging and discharging the charge accumulated in the light emitting element that does not contribute to light emission is long, high gradation display cannot be realized. Therefore, when data is input to the data electrode and the potential of the data electrode shifts from the data-on state to the data-off state, luminance is reduced by providing a period in which the data electrode is in a high impedance state or a floating state. To make up. During this period, a sneak current from the driver IC connected to the scan electrode flows into the light emitting element, so that a reduction in luminance can be suppressed. In other words, a current (charge) that is connected to a non-selected scanning electrode and charged in the reverse direction to the light emitting element that has been input with data is connected to the selected scanning electrode and the light emitting element that has been input with data. By flowing in the forward direction, a decrease in luminance can be suppressed. Also, when the data input to the data electrode is turned off, the non-light emitting element affects the gradation expression during the period when the data electrode is in a high impedance state or floating state for a certain period from the moment of turning off. It is a period that does not give. That is, if the period of the high impedance state or the floating state is long, light emission continues even if the gradation data is turned off. Therefore, the light emission time is set to a period that does not affect the gradation. Then, it is connected to the Gnd potential. At this time, the anode potential of the light emitting element to which the gradation data is input is lower than the difference between the non-selected scan electrode potential and the data electrode potential. That is, it becomes possible to suppress the discharge amount of the light emitting element connected to the data electrode, and the charging time from the non-selected scan electrode necessary to supplement the discharge charge can be shortened. Therefore, sufficient gradation expression is possible.

  According to the present invention, when driving an image display device using a capacitive light emitting element typified by an organic EL display device, the driving circuit does not increase in cost and high gradation image display drive is possible. In addition, an image display apparatus that ensures image quality can be realized.

It is a conceptual diagram including the whole drive circuit of an organic EL image display apparatus. It is a conceptual diagram of a passive matrix image display apparatus. It is a conceptual diagram of the matrix arrangement | sequence of a light emitting element. It is the voltage waveform of the data input into a data electrode. It is a conceptual diagram when the data electrode of a passive type | mold matrix image display apparatus becomes Gnd connection. It is an anode potential and cathode potential diagram of each of the light emitting elements connected to the selected data electrode and the non-selected scanning electrode of the passive matrix image display device. It is explanatory drawing when it is recognized that it became dark. It is explanatory drawing when it is not recognized that it became dark. It is a conceptual diagram of the drive circuit and display apparatus in a light emission state. It is a conceptual diagram at the time of connecting the data electrode into which data was input to Gnd electric potential. It is a conceptual diagram at the time of making the data electrode into which the data was input into a high impedance state or a floating state. 1 is a conceptual diagram of an image display device in which light emitting elements are arranged in a matrix of M + 1 rows and N + 1 columns. It is a current-voltage characteristic diagram of a scan driver. It is a drive conceptual diagram explaining the drive method of the 2nd form of this invention. It is a drive conceptual diagram explaining the drive method of the 2nd form of this invention. It is a figure which shows the gradation data in the case of inputting gradation data into the anode of a display apparatus of 64 rows and 240 columns. It is a figure which shows the relationship between time and input data explaining the drive method of the 2nd form of this invention. It is a figure which shows the relationship between time and input data explaining the conventional drive method. Example 1 shows a current flowing through a light emitting element of Comparative Example 1. FIG. FIG. 2 is a diagram showing a current flowing through a light emitting device of Example 2. It is a figure which shows the structure of an organic electroluminescent image display apparatus. It is a figure which shows the relationship of time of the 1st form of this invention, an anode, a cathode, and an electric current.

In an image display device usually composed of organic EL elements, a constant current circuit can be used as a data driver for inputting to a data electrode. The constant current source regulates a power supply voltage supplied from the outside and outputs a constant current. By using the regulator in this way, the device can be manufactured at low cost, which is economical. Examples of constant current regulators include constant current elements, FETs, and constant current circuits that combine transistors. A typical example can be realized by a current mirror circuit.
For example, as shown in FIG. 1, the display device of the present invention includes a main control unit 104 that provides data to be displayed on a display and data related to display, and an organic EL according to display data provided from the main control unit 104. The display control unit 105 transmits a scan electrode drive signal and a data electrode drive signal which are signals for driving the scan electrode and the data electrode of the display. Further, a display that is connected to the display control unit 105 and stores display data supplied from the main control unit 104 or the like into matrix data, bitmap data, or the like, data of predetermined display contents, or the like. The data storage unit 106, the scan electrode drive signal from the display control unit 105, the scan electrode drive unit 102 that drives the scan electrode and data electrode of the organic EL panel (organic EL display body) 101 by the data electrode drive signal, and the data And an electrode driver 103.

The main control unit 104 gives display data to be displayed on the organic EL display 101, designates display data stored in the display data storage unit 106, and gives timing and control data necessary for display. The main control unit 104 can usually be configured by a general-purpose microprocessor (MPU) and a control algorithm on a storage medium (ROM, RAM, etc.) connected to the MPU. The main control unit 104 can be used regardless of the processor mode such as CISC, RISC, and DSP, and may be configured by a combination of other logic circuits such as ASIC. In this example, the main control unit 104 is provided independently. However, the main control unit 104 may be integrated with a display control unit 105, a control unit of a device equipped with a display, or the like.
The display control unit 105 analyzes display data or the like given from the main control unit 104 or the like, searches for data stored in the display data storage unit 106 as necessary, and displays the display data on a predetermined organic EL display. It is converted into matrix data for display at a position. That is, when the image (image or character) data to be displayed is dot data in pixel units of an organic EL element given at the intersection of each matrix, a signal for driving the scanning electrode and data electrode giving the dot coordinates is given. appear. Further, driving in units of frames as described above, driving ratio (duty) control of the scanning electrodes and data electrodes, and the like are also performed.
The display control unit 105 includes, for example, a processor or a composite logic circuit having a predetermined arithmetic function, a buffer for the processor or the like to exchange data with an external main control unit, a timing signal to the control circuit, a display timing Timing signal generation circuit (oscillation circuit) that gives a read timing signal, a write timing signal, etc., a storage element control circuit that sends and receives display data from an external storage means, a read from an external storage element, A drive signal sending circuit that sends display data given from or processed by the outside as a drive signal, various registers for storing data related to a display function given from outside, a display to be displayed, control commands, etc. Or the like. The display data storage unit 106 includes data (conversion table) for developing image data given from the outside as matrix data on the display, data obtained by developing predetermined character data and image data into matrix data as they are, and the like. The data is stored and can be read (written) by designating a storage position (address) as necessary. As such display data storage means, semiconductor storage elements such as RAM (VRAM), ROM and the like can be preferably cited. However, the display data storage means is not limited to this, and a storage medium (CD-R) applying light or magnetism. , DVD, HD, etc.) may be used.

The scan electrode driving unit 102 and the data electrode driving unit 103 drive the scan electrode and the data electrode according to the scan electrode driving signal and the data electrode driving signal given from the display control unit 105. An organic EL element constituting the organic EL display is a light emitting element that emits light by current drive. Therefore, the power supply when selecting the data electrode is usually about 0.001 to 1 mA on the data side and about 0.001 to 300 mA on the scanning side.
More specifically, a scanning electrode and a data electrode at a predetermined position are driven using a switching element such as a voltage-current conversion element having a necessary current capacity or an amplifying element (power amplification). Examples of the configuration of such a drive circuit include a push-pull circuit. As a switching element such as a voltage-current conversion element or an amplifying element, it is conceivable to use a contact device such as a relay. However, in consideration of high speed operation and reliability, transistors, FETs, and functions equivalent to these. The semiconductor element having These may be integrated circuits such as ICs. These semiconductor elements connect scan electrodes and data electrodes to either the selected power source side or the non-selected power source side. Here, the selected power source side and the non-selected power source side include not only the case of connecting directly to the voltage source, the current source, and the ground line, but also the case of connecting via elements such as a current limiting resistor, a protection device, and a regulator. .

  The organic EL panel 101 is arranged so that a plurality of scanning electrodes and data electrodes intersect, and a specific pixel (organic EL element) emits light by a drive signal applied between these two arbitrary electrodes. It has become. The number of scanning electrodes and the number of data electrodes in the matrix portion are appropriately determined depending on the size and definition of the display, but usually the number of scanning electrodes is 1 to 768 and the number of data electrodes is about 1 to 3072. The above circuit is merely an example of a circuit configuration for driving the organic EL panel (organic EL display main body), and other circuit configurations can be used as long as they have equivalent functions. Further, the display control unit, the scan electrode driving unit, the data electrode driving unit, and the like may be integrated integrally without being clearly divided. Note that these circuit devices are usually configured as one or more types of ICs and their peripheral components.

  As a display driven by the apparatus of the present invention, for example, a display of home appliances such as a microwave oven, an electric rice cooker, an air conditioner, a video, an audio device, an automobile, a speedometer of a two-wheeled vehicle, a tachometer, a navigation system, an audio panel, etc. The various instruments used in various displays, various aircraft, control facilities, etc. are suitably used.

When driving an image display device in which capacitive light-emitting elements typified by organic EL light-emitting elements are arranged in a matrix, scanning electrodes (cathodes) are line-sequentially driven and image data is input to data electrodes (anodes). 2. Description of the Related Art Passive type (line sequential drive) matrix image display devices that realize image display are known. The present invention relates to a passive matrix image display device. FIG. 2 shows a conceptual diagram of a passive matrix image display device. This is a conceptual diagram of the entire image display apparatus, in which light emitting elements are arranged in a matrix, and the number of light emitting elements is the number of scanning electrodes (cathodes) × the number of data electrodes (anodes). For simplicity, consider the case where the light-emitting element is 3 × 3 (FIG. 3). Consider a case where the scan electrode (cathode) is connected and data is input to the data electrode (anode). FIG. 4 shows a voltage waveform of data input to the data electrode. Consider the moment when D2 and D3 are turned off (Gnd) (FIG. 5). At this time, the cathodes of C1.2 and C1.3 are Vo−Vd, and the anode is Gnd potential while maintaining the potential difference of C1.2 and C1.3. The following phenomenon occurs after this time. First, an element connected to a non-selected scan electrode and having a data electrode potential of 0 (off) is charged from the non-selected scan electrode. This corresponds to the transition of the non-selected scanning electrode and the cathode of the element to be turned off from the Vo-Vd potential to the Vo potential. Therefore, the time required for this charging is expressed by the following equation to complete the charging of 95% or more, assuming that the resistance of the non-selected scan driver is α.
Tc = ((− Ln (1−0.95)) − (Ln (Vo−Vd / Vo))) αC (Sec)
It becomes.

  In addition, the following phenomenon occurs in the non-selected scan electrode and the element that is turned on. Charging / discharging occurs so that the anode of this element transitions from 0 to Vd and the cathode transitions from Vo-Vd to Vo (FIG. 6). This is apparent from FIG. Here, consider the case where the anode is a constant current source. Let us consider the behavior of C1.1 and C2.1. Since Vd is a constant current source, first, current flows almost evenly from the data electrode on to all the elements. This is also clear from the fact that the potential difference between the cathode connected to the non-selected scan driver and the anode connected to the data driver is reduced from Vo−Vd, as is apparent from FIG. That is, until a certain time, the element connected to the data electrode is charged in the forward direction. At the same time, the cathode applied to the non-selected scan electrode that is turned off from the data also rises from Vo−Vd to Vo, and the voltage applied to this element generally does not become the forward voltage of the EL element. Discharge occurs so that the absolute value of the discharge becomes small while keeping the sign. Then, after a certain time has elapsed (after the time when the potential difference between the non-selected scan driver and the data driver is minimized), the non-selected scan electrodes and the data-off EL elements start to be charged in the reverse direction. Therefore, after this time, the non-selected scan electrode and the data-on EL element (D1) have a voltage such that the apparent current increases during the time when the C1.1 to C63.1 elements are sufficiently charged in the reverse direction. Rises. This time depends on the time when the cathode voltage of the non-selected scan driver rises. Eventually, the cathode of the non-selected scan driver reaches Vo, and the data driver is in a steady state after a slight overshoot time (FIG. 6). As is apparent from the figure, this series of states depends on the potential of the non-selected scan driver, and the potential of the data driver is determined (depends on the number of EL elements that the scan driver needs to charge). It is important to select a small value for α. (If the anode constant current source has sufficient current supply capability, it is determined by the charging time of the data-off EL element connected to the non-selected scan electrode.) Since α is a voltage-dependent resistance component It is also clear from FIG. 6 that the actual Tc tends to be longer. Further, in this case, since the data electrode once overshoots, it is necessary to discharge in order to correct the overshoot. The time T required here is charged by the charge corresponding to the charge discharged at C1.1 to C63.1. Therefore, when the total charge is Q, it is expressed by the following equation. I: T = Q / I (Sec) as the current flowing through D1.

  The scan driver generally has a high resistance in a high voltage region, and operates close to a constant current source. Therefore, at the moment when the data electrode is turned off, the potential between the scan driver and the selected scan electrode becomes Vo− (Vo−Vd) = Vd potential, and operates so as to shift to 0 potential therefrom. In this case, it operates as a resistor in the low voltage range. Therefore, from the moment when the data electrode is turned off until a certain time, the scan driver operates as a constant current when sufficient current is not supplied for the time determined by the CR product, and after a certain time, it operates as a resistor. And charging up to the time determined by the CR product is performed.

  That is, the potential of the selected scan electrode is determined by the supply capability of the scan driver, and is determined by the time sum of the constant current region (time determined by Q / I) + resistance region (time determined by CR product). Is. Further, the potential of the data electrode depends on the charge / discharge amount, and discharge occurs first, and charging is performed after a certain time. The charge charge and the discharge charge operate to be equal. Here, the data electrode is recognized as dark by humans when the reset operation (the cathode and the anode are set to the Gnd potential) without taking the charge time with respect to the initial discharge time (FIG. 7). ). Of course, when the data driver and the scan driver have sufficient capabilities, the charge / discharge time is shortened, and it is considered that the darkness is not recognized (FIG. 8).

  Then, the form of the 1st drive method of this invention is demonstrated. As described above, after the moment when the data electrode potential becomes 0, a phenomenon may occur in which the luminance of the light emitting element in which the data electrode is connected to the data potential is lowered. Therefore, the following driving method is considered. From the light emission state of FIG. 9 until the time when the non-selected scanning electrode potential becomes Vo−Vth (Vth: light emission threshold) after the moment when the D2 and D3 elements are at the Gnd potential (data electrode is off). The input data electrode is connected to the Gnd potential (FIG. 10). Then, after the time when the non-selected scanning electrode potential becomes Vo−Vth, the data electrode to which data has been input is brought into a high impedance state or a floating state (FIG. 11). When such driving is performed, the following phenomenon occurs. At the moment when the data electrode to which data has been input is connected to Gnd, the non-selected scan electrode potential becomes Vo−Vd. Note that the impedance connected to the Gnd potential of the data electrode is sufficiently lower than the impedance of the non-selected scan electrode. After this time, since the non-light emitting element connected to the non-selected scan electrode is charged from the scan driver, the cathode potential of the non-light emitting element connected to the non-selected scan electrode rises from Vo−Vd to Vo. To do. Here, charging is performed until the cathode potential of the non-light-emitting element connected to the non-selected scan electrode becomes Vo−Vth. If the data electrode to which data has been input is set to a high impedance state or a floating state, the cathode potential of the non-light emitting element connected to the non-selected scan electrode remains at the Vo potential and the anode potential is Since Vth is held, the non-light emitting element connected to the non-selected scan electrode does not emit light. That is, the non-light emitting element is charged until the non-selective scanning electrode potential changes from Vo-Vd to Vo-Vth, but no additional charging occurs thereafter. Therefore, the charge / discharge amount is smaller than when the data electrode to which data has been input is not put into a high impedance state or floating state, and the light emitting element connected to the selected scan electrode and connected to the data electrode Less charge / discharge. Therefore, the consumption can be reduced as compared with the conventional method. In addition, by using this driving method, when the voltage applied to the light emitting element is reduced, the time when the voltage recovers and becomes a steady voltage is that the data electrode where data has been input is in a high impedance state or in a floating state. Compared with the case where it is not necessary, it is shorter, so that multi-tone expression can be realized.

Now, specifically, consider a case where light emitting elements arranged in a matrix are driven by a scanning driver and a constant current circuit in a passive image display device. Consider an image display device in which light emitting elements are arranged in a matrix of M + 1 rows and N + 1 columns as shown in FIG. FIG. 12 shows a case where the light emitting element in the first row and the first column emits light. It is assumed that a constant current source is connected to the anode (data electrode) and a scanning driver is connected to the cathode (scanning electrode). Here, assuming that the current value of the constant current source is Io and the characteristics of the scan driver are approximately shown in FIG. 13, when the scan driver performs a resistance operation and a constant current operation with respect to the drive voltage, the current of the scan driver The value is I, the voltage of the scan driver is V, the power supply voltage of the scan driver is Vo, the voltage after the resistance operation to the constant current operation is Voth, the current when performing the constant current operation is Iso, and the resistance of the scan driver is R Then, I = Iso when 0 ≦ V ≦ Voth, and I = (Vo−V) / R when Voth ≦ V ≦ Vo. Further, characteristics of the light-emitting element is a light-emitting threshold voltage as Vth, the driving voltage _{V D,} the amount of current flowing through the light emitting element and _{I D, I D} = 0 when the _{0 ≦ V D ≦ Vth, Vth} ≦ when V _D are shown as _{I D = (V D -Vth)} · X1. Here, X1 is a constant depending on the light emitting element. Here, assuming that the cathode voltage applied to the non-light emitting element when the scan driver is not selected is V, the operation is considered for the following time. That is, from the state in which all the N + 1 columns are connected to the constant current source and the anodes to the Nnd column (except for the first column) after the Gnd connection, the following four stages are considered. (I) When V _D ≦ Vth and V ≦ Voth. (II) (When V _D ≦ Vth and V ≧ Voth. (III) When V _D ≧ Vth. (IV) After the time when V = Vo−Vth, the data electrode to which data has been input is in a high impedance state. Or in a floating state.

In the case of (I), as shown in FIG. 12, the light emitting elements arranged in the same column direction as the light emitting elements to which the data electrodes are connected are C0 and C3, and the light emitting elements connected in the same row as C0 are C1. , C2, and C4 and C5 are light emitting elements connected to the same row as C3. Assuming that the current value of the constant current source is sufficiently smaller than the current value of the scan driver, Iso >> I _D / M. Therefore, the influence of Io on the charging of I _D to C1, C2, C4, C5 is Since it can be ignored, only the scan driver needs to be considered for charging the light emitting elements (C0 to C5). That is, since it is determined by the constant current operating current of the scan driver, the cathode potential to which C0 and C3 are connected (the potential when the scan electrode is not selected) is shown as follows. With C being the capacity of the light emitting element, V = (1 / NC) · ∫Iso · dt = Iso · t / NC + Const. When the potential difference between the scanning driver and the constant current source is Vco, V = Vco when the potential difference between the scanning driver and the constant current source is Vco. Thus, V = Iso · t / NC + Vco. Since V _D may be obtained by adding the voltage (Vc) charged from V to C0, V _D = V + Vc = Iso · t / NC + Vco + (1 / C) · ∫ (I _D / M) · dt = Iso · t _{/ NC + Vco + I D ·} t / CM + Const. When t = 0, V _D = 0, so Const = −Vco. Therefore, V _D = Iso · t / NC + I _D · t / CM. Also, I _D = 0. Since the range of t is V ≦ Voth and V _D ≦ Vth, Iso · t / NC + Vco ≦ Voth and Iso · t / NC + _ID · t / CM ≦ Vth. That is, t ≦ (Voth−Vco) · NC / Iso≡t0 and t ≦ Vth / (Iso / NC + Io / MC).

In the case of (II) Since the history of the current is the same as (I), V = (1 / NC) ∫ (Vo / R−V / R) · dt
It is indicated.
Solving this, V = Constl · EXP (−t / NCR) + Const2. Since t = ∞ and V = Vo, Const2 = Vo. Since the boundary needs to coincide with (I) at t = t0, Voth = Const1 · EXP ((Voth−Vco) · NC / (Iso · NCR)) + Vo, so Const1 = (Voth−Vo) / EXP ( -(Voth-Vco) /Iso.R). Therefore, V = Vo − ((Vo−Voth) · EXP (−t / NCR)) / EXP (− (Voth−Vco) / Iso · R).
As (Vo−Voth) / EXP (− (Voth−Vco) / Iso · R) ≡X0, V _D = V + Vc = (Vo−X0 · EXP (−t / NCR) + (1 / C) · ∫ (I _D / M) · dt). When the boundaries are matched in the same manner as V, V _D = Vo−Vco + _ID · t / CM−X0 · EXP (−t / NCR). Also, I _D = 0. The range of t is Vo−Vco + _ID · t / CM−X0 · EXP (−t / NCR) ≦ Vth from V _D ≦ Vth. That is, _ID · t / CM−X0 · EXP (−t / NCR) ≦ Vth + Vco−Vo. Therefore, when t ≦ t1, _ID · t / CM−X0 · EXP (−t / NCR) is a monotonically increasing function, and therefore _ID · t1 / CM−X0 · EXP (−t1 / NCR) = Vth + Vco−Vo T1 is defined.

In the case of (III): Is >> I _D / M, and V is the same as (II). Since the light emitting element starts to emit light, the current is set to I1, and the current flowing through the light emitting element connected to the data electrode and connected to the scanning electrode potential that is not selected by the scan driver is set to I2, V _D = V + (1 / MC) ∫I2 · dt = V + (1 / MC) ∫ (I0−I1) · dt = V + (1 / MC) ∫ (I0− (V _D −Vth) · X1) · dt. In general, the solution of y ′ + f (t) · y = r (t) is y = EXP (−h) · (∫EXP (h) · r (t) · dt + C) and h = ∫f (t) · dt It is. In summary by differentiating the _{V D, V D '+ V} D · X1 / MC = V'+ Io / MC + Vth · X1 / MC and h = ∫ (X1 / MC) · dt = X1 · t / MC + constant. This constant will eventually cancel out and can be ignored. Therefore, since it is y = _{V D,} a V D = EXP (-X1 · t / MC) (∫EXP (X1 · t / MC) · (V'+ Io / MC + Vth · X1 / MC) · dt + const). Since V is the same as (II), V _D = Vth + Io / X1 + MC · X0 · EXP (−t / NCR) / (NCR · X1−MC) + Const · EXP (−X1 · t / MC) It is. However, X0 = (Vo−Voth) / EXP (− (Voth−Vco) / Iso · R). The boundary conditions are t = t1 and V _D = Vth. Thus, V _D = Vth + Io / X1 + M · X0 · EXP (−t / NCR) / (NR · X1−M) + ((− Io / X1−M (Vo + Io · t1 / MC−Vth−Vco)) · EXP (X1 · t1 / MC) / (NR · X1-M)) · EXP (−X1 · t / MC). However, X0 = (Vo−Voth) / EXP (− (Voth−Vco) / Iso · R). Further, I _D = (V _D −Vth) · X1.

In the case of (IV) At time t2 when V = Vo−Vth, the data electrode is brought into a high impedance state or a floating state. Vo−Vth = Vo−X0 · EXP (−t2 / NCR). Therefore, t2 = −NCR · Ln (Vth / X0). V = (1 / C) · ∫ (1 / N) · (Vo / R−V / R) · dt + (1 / C) · ∫ (M / N) · (Vo / R−V / R) · dt = ((M + 1) / CNR) · ∫ (Vo−V) · dt. Solving this, V = Vo + Constl · EXP (− (M + 1) t / NCR). From the boundary condition, Vo−Vth = Vo + Constl · EXP (− (M + 1) t2 / NCR), so V = Vo− (X0 ^{M + 1} / Vth ^M ) · EXP (− (M + 1) · t / NCR). Since V _D = V + (1 / MC) ∫I2 · dt, when differentiated and organized in the same manner as in (III), V _D '+ V _D · X1 / MC = V' + I0 / MC + Vth · X1 / MC, the solution is V _D = (M (M + 1) / (NR · X1−M (M + 1))) · X0 ^{M + 1} · EXP (− (M + 1) · t / NCR as in (III) ) / Vth ^M + I0 / X1 + Vth + EXP (−X2 · t / MC) · Const. However, Const = (− Io / X1−M · (Vo + Io · t1 / MC−Vth−Vco) / (NR · X1−M) · EXP (X1 · (t1−t2) / MC) + (M · Xo / NR · X1-M) · EXP (X1 · t2 / MC-t2 / NCR)-(M (M + 1) · X0 · X0 ^M / ((NR · X1−M (M + 1)) · Vth ^M )) · EXP ( X1 · t2 / MC− (M + 1) · t2 / NCR).

The V, V _D , and _ID shown above are shown in FIGS. 22A, 22B, and 22C. The conventional example is a case where the data electrode is not in a high impedance state or in a floating state. From this, it can be seen that the voltage recovery time is short for both the anode potential and the cathode potential by putting the data electrode in a high impedance state or in a floating state. It can also be seen that the current flowing through the data electrode also becomes steady in a short time. In other words, if the recovery time is long, the brightness is reduced by that time, and the brightness is not recovered unless the time until the recovery is waited. Therefore, by shortening the recovery time, the luminance recovery time is shortened, so that multi-tone representation is possible.

  Next, the form of the second driving method of the present invention will be described. As described above, after the moment when the data electrode potential becomes 0, a phenomenon may occur in which the luminance of the light emitting element in which the data electrode is connected to the data potential is lowered. Therefore, the following driving method is considered. From the state shown in FIG. 9, as shown in FIG. 14A, after the moment when the data electrode of the D3 element is turned off, the data electrode to which data has been input for a certain period is set to a high impedance state or a floating state. When such driving is performed, the following phenomenon occurs. At the moment when the data electrode to which data has been input is in a high impedance state or in a floating state, the potential in the high impedance state or in the floating state becomes Vd. Note that the impedance connected to the Gnd potential of the data electrode is sufficiently lower than the impedance of the non-selected scan electrode. Then, after maintaining this state for a certain period of time, the data electrode to which data has been input is set to Gnd connection. At this time, since the non-light-emitting element connected to the selected scan electrode is charged from the scan driver, assuming that the cathode potential of the non-selected scan electrode is Vs, the non-light-emitting element connected to the non-selected scan electrode The cathode potential rises from Vs to Vo. Here, since Vs is in a high impedance state or a floating state, the C2 element is charged up to a voltage at which the D3 element becomes a light emission threshold. For this reason, when the anode of the D3 element is connected to the Gnd potential, Vs does not drop to the Vo-Vd potential, and charging of the non-selected C0 and C1 light emitting elements starting from the moment of connection to the Gnd is reduced. Accordingly, a decrease in luminance of the light emitting element to which the data electrode is connected can be suppressed. Further, in a period of high impedance state or floating state, data is input to the non-selected scan electrode and the data is input up to a voltage at which the light emitting element in which data is input to the data electrode becomes a light emission threshold value. Since the current (charge) for charging the light emitting element in the reverse direction is connected to the selected scan electrode and can flow in the forward direction to the light emitting element to which data has been input, the reduction in luminance is suppressed. Can do.

  Next, the element structure constituting the organic EL display panel used in the present invention will be described. For example, as shown in FIG. 21, the organic EL display 1 has a hole injection electrode (anode), a hole injection / transport layer, a light emission and electron injection transport layer, an electron injection electrode (cathode), and necessary on one substrate 22. Thus, the protective layer is laminated, and this is inverted so that the organic layer is sandwiched between the other substrate 21. In the illustrated example, one extraction electrode 23 is arranged in a direction perpendicular to the other extraction electrode 24, but one extraction electrode 23 is arranged on the opposite side of the other extraction electrode 24 across the substrate 21. May be.

  The organic EL display of the present invention is not limited to the above-described configuration example, and may have various configurations, and may be of a segment type. For example, a light emitting layer is provided independently, and the light emitting layer and the electron injection electrode are provided. It is also possible to adopt a structure in which an electron injecting and transporting layer is interposed therebetween. If necessary, the hole injection / transport layer and the light emitting layer may be mixed. The electron injection electrode can be formed by sputtering or vacuum vapor deposition, the organic layer such as the light emitting layer can be formed by vacuum vapor deposition or the like, and the hole injection electrode can be formed by vapor deposition or sputtering, etc. If necessary, patterning is performed by a method such as etching after mask deposition or film formation, whereby a desired light emission pattern can be obtained. After forming the electrode, a protective film using an inorganic material such as SiOX, an organic material such as Teflon (registered trademark), or the like may be formed. The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film may be formed by sputtering, vapor deposition, or the like. Furthermore, it is preferable to form a sealing layer on the element in order to prevent oxidation of the organic layer and electrode of the element. The sealing layer is an adhesive resin layer such as a commercially available low-hygroscopic photocurable adhesive, epoxy adhesive, silicone adhesive, cross-linked ethylene-vinyl acetate copolymer adhesive sheet, etc. in order to prevent moisture from entering. Is used to adhere and seal a sealing plate such as a glass plate. Besides a glass plate, a metal plate, a plastic plate, etc. can also be used. The light emitting layer has a hole (hole) and electron injection function, a transport function thereof, and a function of generating excitons by recombination of holes and electrons. It is preferable to use a relatively electronically neutral compound for the light emitting layer. The hole injecting and transporting layer has the function of facilitating the injection of holes from the hole injecting electrode, the function of stably transporting holes, and the function of blocking electrons, and the electron injecting and transporting layer is the injection of electrons from the electron injecting electrode. These layers have the function of easily transporting electrons, the function of transporting electrons stably, and the function of blocking holes. These layers increase and confine holes and electrons injected into the light-emitting layer and optimize the recombination region. And improve luminous efficiency. The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer, and the thickness of the electron injecting and transporting layer are not particularly limited, and may vary depending on the forming method, but is usually about 5 to 500 nm, and particularly preferably 10 to 300 nm. . The thickness of the hole injecting and transporting layer and the thickness of the electron injecting and transporting layer may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times depending on the design of the recombination / light emitting region. When the injection layer and the transport layer for holes or electrons are separated, the injection layer is preferably 1 nm or more, and the transport layer is preferably 1 nm or more. The upper limit of the thickness of the injection layer and the transport layer at this time is usually about 500 nm for the injection layer and about 500 nm for the transport layer. Such a film thickness is the same when two injection transport layers are provided. The light emitting layer contains a fluorescent material which is a compound having a light emitting function. Examples of such a fluorescent substance include at least one selected from compounds such as those disclosed in JP-A 63-264692, such as quinacridone, rubrene, and styryl dyes. In addition, quinoline derivatives such as metal complex dyes having 8-quinolinol or a derivative thereof such as tris (8-quinolinolato) aluminum as a ligand, tetraphenylbutadiene, anthracene, perylene, coronene, 12-phthaloperinone derivatives, and the like can be given. Furthermore, a phenylanthracene derivative of Japanese Patent Application No. 6-110568, a tetraarylethene derivative of Japanese Patent Application No. 6-114456, and the like can be used. Further, it is preferably used in combination with a host material capable of emitting light by itself, and is preferably used as a dopant. In such a case, the content of the compound in the light emitting layer is preferably 0.01 to 10 wt%, more preferably 0.1 to 5 wt%. When used in combination with a host material, the emission wavelength characteristic of the host material can be changed, light emission shifted to a longer wavelength can be achieved, and the light emission efficiency and stability of the device can be improved. As the substrate material, a transparent or translucent material such as glass, quartz, or resin is used. Further, the emission color may be controlled by using a color filter film, a color conversion film containing a fluorescent substance, or a dielectric reflection film on the substrate. The color filter film may be a color filter used in a liquid crystal display or the like, but it is only necessary to adjust the characteristics of the color filter according to the light emitted by the organic EL to optimize the extraction efficiency and color purity. . In addition, if a color filter that can cut off short-wavelength external light that is absorbed by the EL element material or the fluorescence conversion layer is used, the light resistance and display contrast of the element can be improved. Further, an optical thin film such as a dielectric multilayer film may be used instead of the color filter. The color conversion film absorbs EL emission light and emits light from the phosphor in the color conversion film to convert the color of the emitted light. The composition includes a binder, a fluorescent material, and light. Formed from three of the absorbent material. The organic EL display is used as a DC drive type, an AC drive or a pulse drive. The applied voltage for driving is usually about 2 to 20V.

In a passive organic EL display device arranged in a matrix of 64 rows and 240 columns, the current value of the constant current source is 300 (μA), the constant current operating current of the scan driver is 2.4 (mA), and resistance operation is performed. The voltage to be transferred is 10 (V), the drive voltage of the scan driver is 18 (V), the resistance value when the scan driver is connected to the power supply voltage is 3.33 kΩ, the capacitance of the unit organic EL element is 18 (pF), When the voltage applied to the characteristics of the organic EL element is 0 to 7 V, the current value = 0 (A). When the voltage applied to the characteristics of the organic EL element is 7 V or more, the voltage applied to the organic EL element is V. Current value = 60 (V−7) (μA). Consider a case where the number of scan electrodes (cathodes) is 64 and the number of data electrodes (anodes) is 240. Consider a case in which the state is shifted from the state where all the light emitting elements in one row and 240 columns emit light, and the state in which only one row and one column elements emit light. (I) When the data potential ≦ 7 and the selected scanning electrode potential ≦ 10. (II) Data electrode potential ≦ 7 and selected scan electrode potential ≧ 10. (III) When the data electrode potential ≧ 7. (IV) After the time when the selected scan electrode potential = 11, it is divided into four types when the non-selected data electrode is put into a high impedance state or a floating state, When the data electrode potential and the current value flowing through the organic EL element are obtained, the time is t.
In the case of (I), the scanning electrode potential of the non-selection line = 0.558 · 10 ⁶ · t + 6 (V), the data electrode potential = 0.823 · 10 ⁶ · t (V), the current value flowing through the organic EL element = 0. This time is t ≦ 7.17 · 10 ⁻⁶ (seconds) because t ≦ 8.51 · 10 ⁻⁶ and t ≦ 7.17 · 10 ⁻⁶ .
In the case of (II), the non-selected scanning electrode potential = 18−13.3 · EXP (−10 ⁶ · t / 14.2) (V), the data electrode potential = 12-13.3 · EXP (−10 ⁶ T / 14.2) + 0.265 · 10 ⁶ · t (V), current value flowing through the organic EL element = 0. Further, this time is 7.17 · 10 ⁻⁶ ≦ t ≦ 8.57 · 10 ⁻⁶ (seconds).
In the case of (III), the non-selected scanning electrode potential = 18−13.3 · EXP (−10 ⁶ · t / 14.2) (V), the data electrode potential = 12−55.1 · EXP (−69. 7 · 10 ³ · t) + 39.5 · EXP (−52.9 · 10 ³ · t) (V), current value flowing through the organic EL element = 60 · 10 ⁻⁶ · (5-55.1 · EXP ( −69.7 · 10 ³ · t) + 39.5 · EXP (−52.9 · 10 ³ · t) This time is 8.57 · 10 ⁻⁶ ≦ t ≦ 9.20 · 10 ^{− 6} (seconds).
In the case of (IV), the time for changing the data electrode to the high impedance state or the floating state is set to 9.20 · 10 ⁻⁶ (seconds) or later, and the non-selected scanning electrode potential = 18−4.67 · 10 ¹⁸ EXP (−4.46 · 10 ⁶ · t) (V), data electrode potential = 12−1.01 ^1.33 · EXP (40.6−4.47 · 10 ⁶ · t) + 4.40 · EXP (−52.9 · 10 ⁴ · t) (V), current value flowing through the organic EL element = 60 · 10 ⁻⁶ · (5-55.1 · EXP (−69.7 · 10 ³ · t) +39. 5 · EXP (−52.9 · 10 ³ · t).
[Comparative Example 1]

In a passive organic EL display device arranged in a matrix of 64 rows and 240 columns, the current value of the constant current source is 300 (μA), the constant current operating current of the scan driver is 2.4 (mA), and resistance operation is performed. The voltage to be transferred is 10 (V), the drive voltage of the scan driver is 18 (V), the resistance value when the scan driver is connected to the power supply voltage is 3.33 kΩ, the capacitance of the unit organic EL element is 18 (pF), When the voltage applied to the characteristics of the organic EL element is 0 to 7 V, the current value = 0 (A). When the voltage applied to the characteristics of the organic EL element is 7 V or more, the voltage applied to the organic EL element is V. Current value = 60 (V−7) (μA). Consider a case where the number of scan electrodes (cathodes) is 64 and the number of data electrodes (anodes) is 240. Consider a case in which the state is shifted from the state where all the light emitting elements in one row and 240 columns emit light, and the state in which only one row and one column elements emit light. At this time, it is assumed that all the elements whose state has shifted are connected to the Gnd potential. In this case, (I) When the data potential ≦ 7 and the selected scan electrode potential ≦ 10. (II) Data electrode potential ≦ 7 and selected scan electrode potential ≧ 10. (III) When the data electrode potential ≧ 7. (I) to (III) are divided into three types, and the non-selected scanning electrode potential, the data electrode potential, and the current value flowing through the organic EL element are determined as time t.
In the case of (I), the non-selected scanning electrode potential = 0.558 · 106 · t + 6 (V), the data electrode potential = 0.823 · 106 · t (V), and the current value flowing through the organic EL element = 0. . Further, since t ≦ 8.57 · 10−6 and t ≦ 7.17 · 10−6, this time is t ≦ 7.17 · 10−6 (seconds).
In the case of (II), the non-selected scanning electrode potential = 18−13.3 · EXP (−10 ⁶ · t / 14.2) (V), the data electrode potential = 12-13.3 · EXP (−10 ⁶ T / 14.2) + 0.265 · 10 ⁶ · t (V), and current value flowing through the organic EL element = 0. Further, this time is 7.17 · 10 ⁻⁶ ≦ t ≦ 8.57 · 10 ⁻⁶ (seconds).
In the case of (III), the non-selected scanning electrode potential = 18−13.3 · EXP (−10 ⁶ · t / 14.2) (V), the data electrode potential = 12−55.1 · EXP (−69. 7 · 10 ³ · t) + 39.5 · EXP (−52.9 · 10 ³ · t) (V), current value flowing through the organic EL element = 60 · 10 ⁻⁶ · (5-55.1 · EXP ( −69.7 · 10 ³ · t) + 39.5 · EXP (−52.9 · 10 ³ · t) This time is 8.57 · 10 ⁻⁶ ≦ t.

  Example 1. When Comparative Example 1 is illustrated, it becomes as shown in FIGS. 19A and 19B, and it can be seen that the time to recover the luminance is shortened. That is, by adopting this driving method, high gradation expression can be realized. It can be seen that the luminance recovery time is 2/3 hours longer than that of the comparative example, which is advantageous for high gradation expression.

As shown in FIG. 16, the organic EL light-emitting elements arranged in a matrix shape of M rows and N columns are divided into 3 equal parts, and 3/3 gradations, 2/3 gradations, Consider the case where 1/3 gradation data is input (see FIG. 17). Here, the gray level means that the larger the value, the longer the light emission time. Consider a case where a data electrode to which data has been input is set to a high impedance state or a floating state. The design parameters are the same as in the first embodiment. The time for switching to the high impedance state or the floating state is as shown in FIG. The states of the respective scan electrodes and data electrodes are shown in FIGS. 14 (A) to 15 (C). When shifting from the light emitting state of FIG. 9 to the state shown in FIG. 14A, since the current of the constant current source is smaller than the current of the scan driver, if it can be ignored, Vo = Vd1 + (1 / NC) · ∫Id1 · dt. Here, the current flowing through the light emitting element in which the cathode is connected to the scanning electrode and the anode is in a floating state is Id1, and the voltage is Vd1. (Note that Vd1 = 12 at initial condition: t = t0 (high impedance state or moment when switching to the floating state).) For simplicity, the voltage Vo of the scan driver is a constant (Vs = Vo). -R · Is). Further, Vd = 7 + 5 · EXP (−5 · 10 ⁻⁶ · t / 24). Next, when shifting to FIG. 14B, Vo = R · Is + (1 / NC) · ∫Is · dt. From this, Is can be obtained. (Initial condition: t = 10 and Is = (Vs = Vc1)) Here, Vc1 means that the cathode of the light emitting element is connected to a non-selected scanning electrode potential in the state of FIG. Represents a potential charged in the period (A) of a light emitting element in a high impedance state or in a floating state, and Vs = 18-10.5 · EXP (−5 · 10 ⁻⁶ · (t−10) 10 ⁻⁶ ) / 24) When Vd ≦ 7 (t ≦ 13.9), Id = 0 and Vd = 12-13.5 · EXP (−5 · 10 ⁶ · (t−10 · 10 ⁻⁶ ) / 24) + 50 · 10 ⁶ · (t−10 · 10 ⁻⁶ ) / 189. When Vd ≧ 7 (t ≧ 13.9), Vd = 12-14.1 · EXP (−5 · ^{10 6 · (t-10 ·} 10 -6) / 24) +1.54 · EXP (-10 · 10 6 · (t-10 · 0 ^-6) / 189), and, Id = (300-846 · EXP ( -5 · 10 6 · (t-10 · 10 -6) / 24) +92.4 · EXP (-10 · 10 6 · ( t-10 · 10 ⁻⁶ ) / 189) · 10 ⁻⁶ Next, from ^FIG.14 (B) to FIG.14 (C) → FIG.15 (A) → FIG.15 (B) → FIG.15 (C). In the case of subsequent processing, it can be obtained in the same manner as the case of shifting to Fig. 14 (A) and Fig. 14 (B), and in the case of Fig. 14 (C) and Fig. 15 (A), Figs. 15B, C is 2C, and in the case of Fig. 15B, C in Fig. 14A is 3C, a current flowing through the light-emitting element connected to the data electrode for which the 3/3 gradation is selected. Is Id3, the voltage is Vd3, the current flowing through the light emitting element connected to the data electrode for which 2/3 gradation is selected is Id2, and the voltage is Vd2. , FIG. 14 (C), the case of FIG. 15 (A), Vd2 = 7 + 5 · EXP (-5 · 10 6 · (t-20 · 10 -6) / 24) .Id2 = 60 · 10 -6 · a Vd2-420 · 10 ⁻⁶ Vo = 18−7.2 · EXP (−5 · 10 ⁶ · (t−30 · 10 ⁻⁶ ) / 48) Vd3 = 12−4.23 · EXP (−5 · 10 ⁶ · (t−30 · 10 ⁻⁶ ) / 48), and Id 3 = 60 · 10 ⁻⁶ · Vd 3 −420 · 10 ^{−6 In} the case of FIG. 7 + 5 · EXP (−5 · 10 ⁶ · (t−40 · 10 ⁻⁶ ) / 144) and Id3 = 60 · 10 ⁻⁶ · Vd3−420 · 10 ⁻⁶ .
[Comparative Example 2]

As shown in FIG. 16, an organic EL light emitting device arranged in a matrix shape of M rows and N columns is divided into N equal parts, and 3/3 gradations, 2/3 gradations, Consider a case where 1/3 gradation data is input (see FIG. 18). Here, the gray level means that the larger the value, the longer the light emission time. Consider a case where a general gradation is realized. The design parameters are the same as in Comparative Example 1. The time for switching to the Gnd potential is as shown in FIG. When shifting from the light emitting state of FIG. 9 to the state shown in FIG. 14B, the current of the constant current source is smaller than the current of the scan driver, so if it can be ignored, Vo = R · Is + (1 / NC) · ∫ Is · dt. From this, Is can be obtained. (Initial condition: t = t0 and Is = (Vo-Vco) / R.) Here, Vco is a potential component due to charges accumulated in 240/3 = 80 columns. For simplicity, the scan driver voltage Vo is a constant (Vs = Vo-R · Is). Here, assuming that the currents of the light emitting elements whose anode is connected to the constant current source and the cathode is connected to the scanning electrode potential are Id, I2, and I3, respectively, as shown in FIG. The potential (anode) is shown below. Vd = Vs + ∫I2 · dt / (M−1). (Initial condition: t = t0 and Vd = 0) Here, when Vd ≦ 7, I2 = IC2. When Vd ≧ 7, I2 = IC2−Id = IC2−60 · 10 ⁻⁶ · Vd + 420 · 10 ⁻⁶ is substituted for Vs, and Vs = 18−12 · EXP (−5 · 10 ⁻⁶ · t / 24) It becomes. Here, IC2 and IC3 are current values of constant current sources. Here, t represents the time when the 1/3 gradation data is turned off as 0. In Vd ≦ 7 (t ≦ 3.4), Id = 0, and Vd = 12-12 · EXP (−5 · 10 ⁶ · t / 24) + 50 · 10 ⁶ · t / 189. When Vd ≧ 7 (t ≧ 3.4), Vd = 12-16.1 · EXP (−5 · 10 ⁶ · t / 24) + 3.51 · EXP (−10 · 10 ⁶ · t / 189) Id = (300−966 · EXP (−5 · 10 ⁶ · t / 24) + 211 · EXP (−10 · 10 ⁶ · t / 189) · 10 ⁻⁶ Next, FIG. When the state is changed to the state of 15 (A), Vo = R · Is + (1 / 2NC) · 。Is · dt Vo = 18−6 · EXP (−5 · 10 ⁶ · (t−20 · 10) ⁻⁶ ) / 48) In the case of Vd ≦ 7 (t ≦ 25.8), Id = 0 and Vd = 12−12 · EXP (−5 · 10 ⁶ · (t−20 · 10 ⁻⁶ ) / 48) at +50 · 10 ⁶ · t / 189 a is .Vd ≧ 7 (t ≧ 25.8) , Vd = 12-12 · EXP (-5 · 10 6 · (t- ^{0 · 10 -6) / 48)} +2.27 · EXP (-10 · 10 6 · (t-20 · 10 -6) / 189) and is, Id = (300-732 · EXP ( -5 · 10 6 (T-20 · 10 ⁻⁶ ) / 48) + 136.2 · EXP (−10 · 10 ⁶ · (t−20 · 10 ⁻⁶ ) / 189) · 10 ⁻⁶

  Example 2 FIG. 20A and FIG. 20B show the current flowing through the data electrode in which the 3/3 gradation of the second comparative example is selected. From this, it can be seen that the embodiment can suppress the decrease in luminance. In the embodiment, the luminance recovery rate is 78.7% at 3/3 gradation, and 40.3% in the comparative example. From this, it can be seen that a reduction in luminance can be suppressed by connecting to the Gnd potential after the high impedance state or the floating state.

101: Organic EL display 102: Scan electrode drive unit 103: Data electrode drive unit 104: Main control unit 105: Display control unit 106: Display data storage unit 21: Substrate 22: Substrate 23: Lead electrode 24: Lead electrode

Claims (2)

A line-sequential driving method of an image display device having an organic electroluminescent element in which scanning electrodes and data electrodes are arranged in a matrix on a substrate, wherein non-selected scanning electrodes are connected to a positive potential and selected While the scan electrode is connected to the Gnd potential, the scan electrode is line-sequentially driven, the non-selected scan electrode is connected to a positive potential, and the selected scan electrode is connected to the Gnd potential. The data electrode is connected to a constant current source, and after the data electrode is disconnected from the constant current source, the data electrode is set to a high impedance state or a floating state for a certain period of time and then connected to the Gnd potential. A driving method characterized by the above. An image display apparatus comprising: a scanning electrode and a data electrode arranged in a matrix on a substrate; an organic electroluminescence element formed at an intersection of the scanning electrode and the data electrode; and a display control unit, wherein the display control The unit drives the scan electrodes line-sequentially via the scan electrode driver, and drives the data electrodes via the data electrode driver, and the display controller sets the non-selected scan electrodes to a positive potential. The selected scan electrode is connected to the Gnd potential, the non-selected scan electrode is connected to a positive potential, and the selected scan electrode is connected to the Gnd potential. After the electrode is connected to a constant current source and the data electrode is disconnected from the constant current source, after being in a high impedance state or a floating state for a certain period of time, G The image display apparatus characterized by connecting to the d potential.

Images