JP2000298456A - Display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent pixels from having differences in luminance and being shadowed corresponding to a light emission pattern through simple constitution. SOLUTION: The display device is equipped with an organic EL display unit 1, a scanning electrode drive part 2, and a data electrode drive part 3. The display unit 1 has scanning electrodes COM1 to COMn and data electrodes SEG1 to SEGm arranged in matrix and organic EL elements EL1,1 to ELm,n as light emitting elements which are formed at the intersections of the scanning electrodes and data electrodes and connected to both the electrodes. The data electrode drive pat 3 makes all the data electrodes unselected for a specific period when scanning electrodes selected by the scanning electrode drive part 2 are switched so that the organic EL elements connected to all the data electrodes are placed in the same electric charge storage state of the parasitic capacity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device provided with a display device having a scanning electrode, a data electrode, and a plurality of light emitting elements arranged at a portion where the two electrodes intersect and connected to the two electrodes. About.

[0002]

2. Description of the Related Art In recent years, as a light emitting element capable of realizing a thin and flat light emitting display device, an organic electroluminescent (hereinafter referred to as EL) element has been actively studied and put into practical use. This organic E
The L element is a charge injection / recombination type EL element using an organic material as a light emitting material, and has various characteristics such as self-emission, high luminance, high viewing angle, low power consumption, low voltage driving, and high efficiency. The application of is expected. Above all, organic EL elements
Various display devices, in particular, applications to flat panel displays have been attempted. A display device using an organic EL element can be used in home electric appliances, electric components of automobiles and motorcycles, and the like. Specifically, this display device
It can be used for an information display panel used in audio equipment, an instrument panel for an automobile, a display device for displaying a moving image or a still image, and the like.

In an organic EL device, for example, a thin film of a hole transport material such as triphenyldiamine (TPD) is formed on a transparent electrode (hole injection electrode) such as tin-doped indium oxide (ITO) by vapor deposition. A fluorescent material such as an aluminum quinolinol complex (Alq ₃ ) is laminated thereon as a light emitting layer, and a metal electrode (electron injection electrode) having a small work function such as magnesium (Mg) is further formed thereon. Element. This organic EL element
Several hundred to several 10,000 cd / m at a voltage of around 10 V
^Since an extremely high luminance of ² can be obtained, attention is paid to its use for display devices in home electric appliances, electric components of automobiles and motorcycles, and the like.

[0004] Such an organic EL element usually includes, for example, a scan electrode (common line) serving as an electron injection electrode,
Usually, a data electrode (segment line) serving as a hole injection electrode (transparent electrode) sandwiches an organic layer having a light emitting function, and has a structure in which these are formed on a transparent substrate such as glass.

A display device using an organic EL element is roughly classified into a display device having a matrix electrode configuration and a display device having a segment electrode configuration depending on its electrode configuration. In a display device having a matrix electrode configuration, a plurality of pixels (dots) are formed by scanning electrodes and data electrodes arranged in a matrix, and information such as images and characters is displayed by a combination of pixels to emit light. . A display device having a segment electrode configuration has a plurality of independent display elements having a predetermined shape and size, and displays a predetermined pattern by a combination of display elements to be driven.

On the other hand, the driving method of the display device includes a static driving method in which each display element is driven independently and independently, and a dynamic driving method in which a plurality of scanning electrodes and data electrodes are time-divisionally driven. The static driving method is mainly used in a display device having a segment electrode configuration.
In a display device having a matrix electrode configuration, a dynamic drive system is usually employed. The dynamic driving method includes two types of driving: a case where the electron injection electrode is used as a scanning electrode and a hole injection electrode is used as a data electrode, and a case where the electron injection electrode is used as a data electrode and the hole injection electrode is used as a scanning electrode. There is a method.

Here, with reference to FIG. 20, an example of a configuration of a display device driven by a dynamic driving method in a matrix electrode configuration will be described. FIG. 20 shows an example in which the electron injection electrode is used as a scan electrode and the hole injection electrode is used as a data electrode. This display device includes an organic EL display 101 and a scan electrode driver 102.
And a data electrode driving unit 103.

The display 101 includes scanning electrodes COM1 to COMn and data electrodes SEG arranged in a matrix.
1 to SEGm and a plurality of organic ELs formed at the intersections of these scanning electrodes and data electrodes and connected to both electrodes.
Elements EL _{1,1 to} EL _{m, n} are provided. The code COM
x (x = 1 to n) represents an x-th row of scanning electrodes,
EGy (y = 1 to m) represents a scanning electrode on the y-th column, and reference characters EL _{x, y} represent organic EL elements on the x-th row and the y-th column.

[0009] The scan electrode drive section 102 is connected to the scan electrodes COM1 to COMn of the display 101, and drives the scan electrodes COM1 to COMn. The data electrode driver 103 is connected to the data electrode SE of the display 101.
G1 to SEGm and connected to the data electrodes SEG1 to SEG1.
SEGm is driven.

[0010] The scan electrode driver 102 has n switches SW1 ₁ ~SW1 _n. Each of the switches SW1 ₁ ~
The movable contacts of SW1 _n are scan electrodes COM1 to COM1, respectively.
Connected to COMn. Each switch SW1 _{1 to} SW
The one fixed contact of the two fixed contacts 1 _n, the power supply voltage Vcc is applied. Each switch SW1 ₁ ~S
A ground potential is applied to the other fixed contact of W1 _n . The scan electrode drive unit 102 connects the movable contact of a certain switch to the fixed contact on the ground potential side to select the scan electrode connected to that switch, and sets the movable contact of the other switch to the power supply voltage Vcc side. By connecting to the fixed contact, the scanning electrode connected to another switch is set to the non-selection state. The scan electrode driver 102, such an operation, sequentially repeated from the switch SW1 ₁ to switch SW1 _n, performs line sequential driving.

[0011] Data electrode driving unit 103 includes m-numbered switches SW2 ₁ ~SW2 _m. Each switch SW2 ₁
To SW2 _m are connected to the data electrodes SEG ₁ , respectively.
To SEG _m . Each switch SW2 _{1 to} SW
One end of the constant current sources I1 to Im is connected to one of the two fixed contacts of 2 _m , respectively.
The other ends of the constant current sources I1 to Im are connected to a voltage source 1 of a power supply voltage Vcc.
04 is grounded. Each switch SW2 ₁ ~S
Other fixed contact of W2 _m is grounded. The data electrode driving unit 103 is connected to the switch S of the scan electrode driving unit 102.
In synchronization with the operation of W1 _{1 to} SW1 _n , the switches SW2 ₁ to SW1
When SW2 _m is operated and a certain scan electrode is in the selected state,
Connect the desired data electrode to the constant current source to select it,
The other data electrodes are grounded to be in a non-selected state. As a result, a constant current is supplied to the organic EL element connected to the selected scanning electrode and the selected data electrode, and this organic
The L element emits light.

The scan electrode driver 102 applies a power supply voltage Vcc to the scan electrodes in the non-selected state. Further, the data electrode driving unit 103 applies the ground potential (0 V) to the data electrode in the non-selected state. This prevents erroneous light emission due to current sneak.

[0013]

FIG. 21 shows an organic EL element represented by an equivalent electric circuit.
That is, the organic EL element is represented as a parallel circuit of the diode element D and the parasitic capacitance Cp. In the conventional display device, since the organic EL element has the parasitic capacitance Cp, there are two problems as described below.

First, regarding the first problem, the scanning electrode C
OM1, COM2 and data electrodes SEG1, SEG2
The description will be made by taking as an example a case where the organic EL elements EL _1,1 , EL _1,2 , EL _2,2 emit light.

FIG. 22 shows an example of a change in the state of the scanning electrodes and the data electrodes when the above-mentioned light emitting operation is performed. In this figure, (a) shows the scanning electrode COM1.
(B) shows a change in the voltage of the scan electrode COM2, (c) shows a change in the voltage of the data electrode SEG1, and (d) shows a change in the voltage of the data electrode SEG2. . The voltages of the scan electrodes COM1 and COM2 become low level in the selected state, and the data electrodes SEG
1. The voltage of SEG2 is at a high level in the selected state. In this example, first, the scanning electrode COM1 is in a selected state, and at this time, the data electrode SEG1 is in a selected state, and the data electrode SEG2 is in a non-selected state. next,
Scan electrode COM2 is selected, and at this time, data electrode SEG1 and data electrode SEG2 are both selected.

FIG. 23 shows the state of the organic EL element when the scanning electrode COM1 is in the selected state. In this figure, only the parasitic capacitance is shown for the organic EL element. As shown in this figure, when the scan electrode COM1 is in the selected state, the data electrode SEG1 is in the selected state, and the organic EL element EL _{1,1 at} the intersection of the scan electrode COM1 and the data electrode SEG1 moves in the forward direction. It emits light because it is biased. The other organic EL elements EL _{1,2 to} EL _{1, n} connected to the data electrode SEG1 have the parasitic capacitance C _1,2 because the power supply voltage Vcc is applied to the corresponding scan electrode.
~ C _{1, n} is a state in which no charge is accumulated. In practice, the constant current source connected to drive the data electrode at a constant current adjusts the voltage applied to both ends of the constant current source to keep the current flowing through the data electrode constant. At the time of electrode selection, the voltage of the data electrode SEG1 is lower than the power supply voltage Vcc. Thus, although the charge in the opposite direction of the organic EL elements are slightly accumulated in the parasitic capacitance C _{1, 2} -C 1, _n of the organic EL element EL _1,2 ~EL 1, _n, in order to simplify the description This slightly accumulated charge is ignored in the following description.

The parasitic capacitance C _2,1 of the organic EL element EL _2,1 is
Since both the data electrode SEG2 and the scan electrode COM1 are at the ground potential, no charge is stored. Also,
Other than the parasitic capacitance C _2,1 of the organic EL element EL _2,1, the parasitic capacitance C _{2, 2} -C 2, _n connected to the data electrode SEG2, since the power supply voltage Vcc to the scanning electrodes are connected, reverse The electric charge is accumulated.

FIG. 24 shows a transient state when the selected scan electrode changes from scan electrode COM1 to scan electrode COM2. This figure also shows only the parasitic capacitance for the organic EL element. As shown in this figure, the data electrode SEG1 is in the selected state as in the state shown in FIG. 23, and is connected to the constant current source I1. The organic EL elements EL ₁ , ₂ are in a selected state because they are connected to the data electrode SEG1 and the scan electrode COM2.
The parasitic capacitance C _{1, 2} of the organic EL element EL _{1, 2,} as indicated by an arrow in the figure, with the current from the constant current source I1 flows, the organic EL element is biased in the forward direction just through the parasitic capacitance C _{1, 1} of EL _{1, 1,} current flows by the power supply voltage Vcc of the scanning electrode side connected to the scanning electrode COM1. With these currents, the organic EL element EL
_Electric charges are accumulated in the parasitic capacitances C _1,2 of the organic EL elements EL _{1,2 in} the forward direction of the organic EL elements EL _1,2 , and the organic EL elements EL _1,2 emit light.

The organic EL elements EL2 and _EL2 are also in the selected state. However, the current from the constant current source I2, as indicated by the arrows, not only the parasitic capacitance C _{2, 2} of the organic EL element EL _{2, 2,} parasitic capacitance C _2,3 -C 2 organic EL _elements, It also flows to the discharge path of _n . Therefore, (c) and (d) of FIG.
As shown in the _figure , the parasitic capacitance C _{2 , 2} of the organic EL element EL _2,2
Forward the charges are accumulated, the data electrode SEG2 is stabilized potential, if the parasitic capacitance C _{1, 2,} i.e., time-consuming than that of the data electrodes SEG1. Therefore, even when the same selection state is selected, when the organic EL elements EL _1,2 and the organic EL elements EL _2,2 are compared, the organic EL element E
L1, _{2 has} a higher emission luminance. As described above, in the related art, there is a first problem that a difference occurs in light emission luminance of each pixel according to a light emission pattern, and display quality of a display device is significantly reduced.

In particular, since the organic EL element is a surface-emitting element, the larger the parasitic capacitance Cp and the larger the size of the display, the larger the difference in luminance between pixels according to the above-mentioned light emission pattern. Would.

Japanese Patent Application Laid-Open No. 9-232074 discloses that in order to increase the rising speed from the start of the supply of the drive current to the emission of light, all the scan electrodes are temporarily set to the same state when switching to the next scan electrode. A technique of connecting to a reset potential comprising a potential is shown. However, this technique has the following problems.

In the following description, a period in which all the scanning electrodes or data electrodes are connected to the reset potential is called a reset period. The above publication discloses an example in which a reset period is provided only for driving a scan electrode, and an example in which a reset period is provided for both drive of a scan electrode and drive of a data electrode.

First, consider the case where a reset period is provided only for driving the scanning electrodes. First, when the reset period is set by shifting only the timing at which the scan electrode switches from the selected state to the non-selected state by a predetermined time before the timing at which the scan electrode originally switches, no improvement effect is seen. Next, when the reset period is set by delaying only the timing at which the scan electrode switches from the non-selected state to the selected state by a predetermined time as compared with the timing at which the scan electrode originally switches, an improvement effect can be seen.
However, in this case, at the moment when the element to emit light is selected, current flows not only from the data electrode but also from the voltage source connected to all the other scanning electrodes to the element to emit light (particularly). See FIG. 3 of JP-A-9-232074). Therefore, a large rush current flows through the scan electrode to which the element that emits light is connected. for that reason,
It is necessary to take measures against the inrush current to the scanning electrodes, and there is a problem that the circuit of the scanning electrode driving unit becomes complicated and the scale becomes large.

Also, consider a case where a reset period is provided for both the driving of the scanning electrodes and the driving of the data electrodes. Also in this case, similarly to the above case, a large rush current flows to the scanning electrode to which the element to emit light is connected, which is not preferable.

Next, the second problem will be described. The organic EL element has a structure in which an organic material is laminated between two electrodes, and is a capacitive load. Therefore, when the organic EL element is driven at a constant voltage, the drive circuit of the electrode is driven in accordance with the problem that the drive circuit is broken by the inrush current and the time constant determined by the capacity of the organic EL element and the resistance of the electrode and the like. There is a problem that the rise time and the fall time are long. When the organic EL element is driven with a constant current, the inrush current is suppressed, but the capacitive load is generally driven such that the rising waveform of the drive voltage of the organic EL element becomes dull and a light emission delay occurs. Various problems may occur.

Among the problems of the organic EL element due to the capacitive load of the organic EL element, shadowing is mentioned as a second problem here, in particular. Shadowing refers to a phenomenon in which the luminance in a certain area changes from the original luminance in accordance with the state of an adjacent area. Hereinafter, this shadowing will be described.

First, an example of shadowing will be described with reference to FIG. This figure shows an example of a display screen in a display device using an organic EL element. In FIG. 25, the vertical direction is the arrangement direction of the scanning electrodes, and the horizontal direction is the arrangement direction of the data electrodes. In the example shown in FIG.
In a region corresponding to the plurality of scanning electrodes in a substantially central portion in the vertical direction of the display screen, a substantially left half is a non-light emitting region 112 where the organic EL element does not emit light, and a substantially right half is a light emitting region where the organic EL element emits light. An area 113 is provided. The areas above and below these areas 112 and 113 are:
A plurality of organic EL elements connected to each scanning electrode form a light emitting region 111 that emits light.

In a display device using an organic EL element,
When a symbol as shown in FIG. 25 is displayed, the non-light-emitting area 1
The light emission luminance of the organic EL element in the light emitting region 113 connected to the same scan electrode as the organic EL element in 12 is lower than the light emission luminance of the organic EL element connected to the scan electrode in the light emitting region 111 where there is no organic EL element that does not emit light. A phenomenon (also referred to as a white spot phenomenon) that is larger than that occurs occurs. This phenomenon is an example of shadowing. This phenomenon significantly reduces display quality.

The phenomenon described with reference to FIG. 25 is that, as the number of organic EL elements that emit light at a given scanning electrode decreases, the crosstalk of the organic EL element that emits light connected to that scanning electrode increases. Organic EL that emits light more than
The number of elements is larger than that of the light-emitting organic EL element connected to another scan electrode, and the light emission luminance of the light-emitting organic EL element connected to any scan electrode is higher than that of the other scan electrode. It can be said that this is a phenomenon that becomes brighter than the emission luminance of the organic EL element that emits light.

Next, two of the causes of shadowing will be described. In the following description, the voltage of the scanning electrode is low (in the figure, L) in the selected state, and high in the non-selected state (H, in the figure), and conversely. The voltage of the data electrode is at a high level in the selected state and is at a low level in the non-selected state.

First, one of the causes of shadowing is as follows.
Will be described. As described above, since the organic EL element is a capacitive load, the rise time of the scan electrode changes according to a time constant determined by the capacitance of the organic EL element and the resistance of the electrodes and the like. Therefore, the rise time of the scan electrode changes depending on the magnitude of the capacitance viewed from the scan electrode side.

FIG. 26 shows the relationship between the potential difference between both ends of the organic EL element and the state of electric charge stored in the organic EL element. In FIG. 26, with respect to the organic EL element, attention is paid only to the capacitance component, and the organic EL element is represented as a capacitor having one end connected to the scanning electrode (cathode) and the other end connected to the data electrode (anode). In FIG. 26, the high-level voltage applied to the scanning electrodes and the data electrodes is the power supply voltage Vcc, and the low-level voltage is the ground potential. In addition,
The display method of the organic EL element and the voltages applied to the scanning electrodes and the data electrodes are the same as in FIG. 26 in FIGS. 27 to 29 to be referred later.

As shown in FIG. 26, the organic EL device
When the scanning electrode is in the selected state and the data electrode is in the selected state, the bias is applied in the forward direction, a forward potential difference is generated at both ends of the organic EL element, and charges are accumulated in the organic EL element in the forward direction. Further, the organic EL element is biased in the reverse direction when the scanning electrode is in the non-selected state and the data electrode is in the non-selected state, and a potential difference in the opposite direction occurs at both ends of the organic EL element,
Electric charges are accumulated in the organic EL element in the opposite direction. Further, the organic EL element is not biased in the forward or reverse direction when the scan electrode is selected and the data electrode is not selected, and when the scan electrode is not selected and the data electrode is selected. No potential difference occurs between both ends of the organic EL element, and no charge is accumulated in the organic EL element.

Next, referring to FIG. 27, when the scanning electrode changes from the selected state to the non-selected state, how the state of the charge stored in the organic EL element changes depending on the state of the data electrode. Will be described.

As shown in FIG. 27, when the data electrode changes from the selected state to the non-selected state when the scanning electrode changes from the selected state to the non-selected state, the data is accumulated in the organic EL element in the forward direction. After the released charge has been released, the organic E
Electric charges are accumulated in the L element in the reverse direction. In addition, when the scan electrode changes from the selected state to the non-selected state, and the data electrode maintains the selected state, the charges accumulated in the organic EL element in the forward direction are released. When the data electrode changes from the unselected state to the selected state when the scanning electrode changes from the selected state to the non-selected state, the organic electrode
The potential difference between both ends of the L element remains unchanged at zero and the organic EL
The state where no charge is accumulated in the element is maintained. In addition, when the scan electrode changes from the selected state to the non-selected state, if the data electrode maintains the non-selected state, charges are accumulated in the organic EL element in the reverse direction.

As described above, when the scan electrode changes from the selected state to the non-selected state, when the data electrode changes from the selected state to the non-selected state, and when the data electrode maintains the non-selected state, Since charges are accumulated in the organic EL element, the rising waveform of the voltage of the scan electrode becomes dull compared to other cases. From this, it can be seen that the more the unselected data electrodes are in a given scan electrode, the duller the rising waveform of the voltage of the scan electrode becomes. An example showing this will be described with reference to FIGS. In order to simplify the description, in the following description, it is assumed that four data electrodes are connected to one scanning electrode via four organic EL elements.

FIG. 28 shows that when the scanning electrode changes from the selected state shown in (a) to the non-selected state shown in FIG.
The case where all the data electrodes maintain the selected state is shown. In this case, the charges accumulated in the forward direction in the four organic EL elements are released.

FIG. 29 shows that when the scanning electrode changes from the selected state shown in (a) to the non-selected state shown in FIG.
The case where three data electrodes maintain a selected state and three data electrodes maintain a non-selected state is shown. In this case, in the organic EL element connected to one data electrode maintaining the selected state, the charge accumulated in the forward direction is released, and the organic EL element connected to the three data electrodes maintaining the non-selected state is released. In the EL element, charges are accumulated in the opposite direction.

As can be seen from a comparison between FIG. 28 and FIG. 29, in an arbitrary scanning electrode, the more unselected data electrodes, that is, the more organic EL elements that do not emit light,
The charge accumulated in the organic EL element in the reverse direction increases, and as a result, the rising waveform of the voltage of the scan electrode becomes dull.

In FIG. 30, (a) shows the rising waveform of the voltage of the scanning electrode when the number of unselected data electrodes is small, and (b) shows the rising waveform of the voltage of the scanning electrode when there are many unselected data electrodes. Is shown.
As shown in this figure, the rising waveform of the voltage of the scanning electrode becomes slower when there are many unselected data electrodes than when there are few unselected data electrodes. As a result, in the case where there are many unselected data electrodes shown in (b), the time t2 until the voltage of the scan electrode reaches a certain value from zero is equal to the case where the number of unselected data electrodes shown in (a) is small. , The time is longer than the time t1 until the voltage of the scanning electrode reaches a certain value from zero.

The organic EL element emits light when the potential difference between the data electrode and the scanning electrode is equal to or greater than a predetermined threshold.
Therefore, as shown in FIGS. 30A and 30B, if the rising waveform of the voltage of the scan electrode becomes dull, the scan electrode is not connected to the data electrode for a certain period after the scan electrode shifts from the selected state to the non-selection period. The potential difference between the electrode and the electrode becomes equal to or higher than the threshold, and the organic EL element emits light. As described above, even after the scanning electrode shifts from the selected state to the non-selection period, the organic EL device
When the element emits light, the emission luminance of the organic EL element increases. The period during which the organic EL element emits light after the scanning electrode shifts from the selected state to the non-selection period is shown in FIG.
The longer the times t1 and t2 in (b), the longer. Accordingly, as the number of non-selected data electrodes in an arbitrary scan electrode, that is, the more organic EL elements that do not emit light, the more the organic EL element that emits light is connected to the arbitrary scan electrode.
The light emission luminance of the element increases. Thus, FIG.
Shadowing occurs as shown in FIG.

Next, another cause of the shadowing will be described. Shadowing is caused by the above-described blunting of the rising waveform of the voltage of the scan electrode and the difference in transition of the state of the data electrode before and after the scan electrode shifts from the selected state to the non-selection period. It also occurs due to variation. Shadowing caused by this cause occurs because the light emission luminance of an organic EL element connected to a certain scan electrode is affected by the state of the organic EL element connected to an adjacent scan electrode. It can be called cross talk.

Hereinafter, another cause of the shadowing will be described in detail with reference to FIG. FIG. 31 shows an example of a change in the state of the scanning electrode and the data electrode. In this figure, (a) shows a change in voltage of an arbitrary scan electrode (1), (b) shows a change in voltage of a scan electrode (2) next to the scan electrode (1),
(C) shows a change in the voltage of an arbitrary data electrode.
In this example, first, the scanning electrode (1) is in a selected state, and at this time, the data electrode is in a selected state. Next, the scanning electrode (2) is in the selected state.
In the example shown by the solid line in (c), the data electrode is in a non-selected state.

There are the following four modes of transition of the state of the data electrode before and after the scan electrode (1) shifts from the selected state to the non-selection period. The first mode is a mode in which the data electrode shifts from a selected state to a non-selected state. In FIG. 31C, the solid line indicates the first mode. The second mode is a mode in which the data electrode maintains the selected state. In FIG. 31C, the broken line indicates the second mode. A third mode is a mode in which the data electrode maintains the non-selected state. The fourth mode is a mode in which the data electrode shifts from the non-selected state to the selected state. When the data electrode shifts from the non-selected state to the selected state and when the data electrode shifts from the selected state to the non-selected state, similarly to the case of the scan electrode, the capacity of the organic EL element and the In accordance with the time constant determined by the resistance, the rising waveform and the falling waveform of the voltage of the data electrode become dull.

Hereinafter, with respect to the above-described first to fourth aspects, the rising waveform of the voltage of the scan electrode becomes dull and the transition of the state of the data electrode before and after the scan electrode shifts from the selected state to the non-selection period. The effect of the difference on the light emission luminance of the organic EL element will be described.

In the first mode, since both the rising waveform of the voltage of the scanning electrode (1) and the falling waveform of the voltage of the data electrode become dull, the scanning electrode (1) shifts from the selected state to the non-selection period. Thereafter, for a certain period, the potential difference between the data electrode and the scanning electrode (1) becomes equal to or larger than the threshold value, and the organic EL element emits light. Therefore, the light emission luminance of the organic EL element increases.

In the second mode, since the voltage of the data electrode maintains the high level and the rising waveform of the voltage of the scan electrode (1) becomes dull, the scan electrode (1) shifts from the selected state to the non-selection period. Also, during a certain period, the potential difference between the data electrode and the scanning electrode (1) becomes higher than the threshold value, and
The device emits light. Therefore, the light emission luminance of the organic EL element increases.

Here, comparing the first mode and the second mode, the voltage of the data electrode falls in the first mode, while the voltage of the data electrode maintains the high level in the second mode. Therefore, after the scan electrode (1) shifts from the selected state to the non-selection period, the period during which the potential difference between the data electrode and the scan electrode (1) is equal to or larger than the threshold, that is, the organic E
The period during which the L element emits light is longer in the second mode than in the first mode. Therefore, the increase in the light emission luminance of the organic EL element is larger in the second embodiment than in the first embodiment.

In the third mode, since the voltage of the data electrode maintains the low level, after the scanning electrode (1) shifts from the selected state to the non-selection period, the voltage between the data electrode and the scanning electrode (1) is changed. The potential difference does not exceed the threshold, and the light emission luminance of the organic EL element does not increase.

In the fourth mode, both the voltage of the scan electrode (1) and the voltage of the data electrode rise. Therefore, in this case, the influence on the light emission luminance of the organic EL element differs depending on whether the rising waveform of the voltage of the scanning electrode (1) or the rising waveform of the voltage of the data electrode is steep.

For example, when the data electrode is driven at a constant voltage, the rising waveform of the voltage of the data electrode is steeper than the rising waveform of the voltage of the scanning electrode (1). Therefore, in this case, even after the scan electrode (1) shifts from the selected state to the non-selection period, for a certain period, the potential difference between the data electrode and the scan electrode (1) becomes equal to or larger than the threshold value, The organic EL element emits light, and the light emission luminance of the organic EL element may increase. However, in this case, the potential difference between the data electrode and the scan electrode (1) becomes greater than or equal to the threshold after the scan electrode (1) shifts from the selected state to the non-selection period, as compared to the first mode. The period during which the organic EL element emits light is extremely short, and the increase in the light emission luminance of the organic EL element is extremely small.

On the other hand, when the data electrode is driven with a constant current, the rising waveform of the voltage of the data electrode does not become steeper than the rising waveform of the voltage of the scanning electrode (1). Therefore, in this case, the potential difference between the data electrode and the scan electrode (1) does not exceed the threshold value after the scan electrode (1) shifts from the selected state to the non-selection period. There is no increase in light emission luminance of the device.

As described above, shadowing also occurs due to the difference in light emission luminance of the organic EL element depending on the change in the state of the data electrode before and after the scan electrode shifts from the selected state to the non-selection period.

Conventionally, the following countermeasures have been considered for the shadowing described above.

It is well known that shadowing also occurs in a liquid crystal display (hereinafter, referred to as LCD). As a countermeasure against shadowing in an LCD, a technique of detecting a variation in potential on the same scanning electrode and compensating for a potential as disclosed in Japanese Patent Application Laid-Open No. 4-191821 or a method disclosed in Japanese Patent Application Laid-Open No. Many countermeasures have been proposed, such as a technique for applying a compensation voltage to a signal voltage applied to a scanning electrode as disclosed in the publication.

However, the cause of the shadowing in the LCD is a variation in the potential on the same scanning electrode, whereas the cause of the shadowing in the organic EL display device is, as described above, the voltage of the scanning electrode and the data electrode. The waveform of the rise or fall of the voltage is blunted. Therefore, measures against shadowing in LCDs must be
It is difficult to convert the display device as it is to take measures against shadowing in the display device.

It is known that shadowing also occurs in an inorganic EL (thin film EL) display device. Shadowing in an inorganic EL display device is caused by a voltage drop due to an on-resistance of a driving circuit due to an increase in load current accompanying an increase in light emitting pixels.
Therefore, in the inorganic EL display device, as the number of EL elements that emit light simultaneously among the EL elements connected to a certain scanning electrode increases, the luminance of the EL element that emits light decreases.

As a countermeasure against shadowing in the inorganic EL display device, a technique of applying a constant or almost constant voltage to the electrodes by using a drive voltage correction control circuit or a technique disclosed in
As shown in US Pat.
There is a technique that has been tried with a display device that performs gradation display.

However, in the organic EL display device, the organic EL
The light emission luminance of the device depends on the current density of the current flowing through the organic EL device. Therefore, in the organic EL display device, it is desirable to control the current density of the current flowing through the organic EL element to be equal regardless of whether the driving is performed by the constant current or the constant voltage. Therefore, as a measure against shadowing in an organic EL display device driven so that a constant current flows through the organic EL element, it can be said that it is not sufficient to use only the above-described drive voltage correction control circuit.

In the organic EL display device, since the organic EL element is a capacitive load, there is a problem that the rising speed of light emission becomes slow in addition to shadowing. As a countermeasure against this, Japanese Unexamined Patent Publication No. 9-232074 mentioned in the description of the first problem discloses a reset period in which all the scan electrodes are once connected to a reset potential having the same potential when the scan electrodes are switched. The technology to be provided is shown. Therefore, it is conceivable to use this technique for measures against shadowing.

However, in an organic EL display device driven by a constant current, a data electrode drive circuit that drives a data electrode at a constant current operates to keep the current flowing through the data electrode constant. Therefore, in such an organic EL display device, as described above, when the reset period for connecting the scan electrode to the reset potential is provided, the data electrode driving circuit increases the potential difference between the scan electrode and the data electrode. Therefore, the reset period does not play its original role. Therefore, the technique of providing a reset period for connecting the scan electrode to the reset potential is insufficient as a countermeasure for shadowing.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent a difference in luminance of each pixel according to a light emission pattern and a generation of shadowing with a simple configuration. It is an object of the present invention to provide a display device capable of performing such a display.

[0063]

A display device according to the present invention comprises a plurality of scan electrodes, one or more data electrodes provided so as to intersect the plurality of scan electrodes, and a portion intersecting these two electrodes. A display having a plurality of light-emitting elements disposed and connected to both electrodes, and emitting light when a potential difference between the two electrodes is equal to or greater than a predetermined threshold value; and different potentials in a selected state and a non-selected state of a scanning electrode. And a scanning electrode driving means for driving the scanning electrodes so that the scanning electrodes are sequentially set to the selected state, and a potential difference between the selected scanning electrode and the selected data electrode becomes equal to or larger than a threshold value. Data electrode driving means for driving the data electrode so that the data electrode has a different potential between a selected state and a non-selected state, and driving the data electrode to an arbitrarily selected state. The data electrode driving means comprises a scanning electrode Drive By controlling the potential of the data electrode when the scanning electrode that is selected by the step is switched, the potential difference between all the scanning electrodes and all the data electrodes is temporarily reduced to less than the threshold value. is there.

In the display device of the present invention, a potential difference equal to or greater than the threshold is applied to the light emitting element at the intersection of the scan electrode selected by the scan electrode driving means and the data electrode selected by the data electrode driving means. The light emitting element emits light. The data electrode drive unit controls the potential of the data electrode when the scan electrode switched to the selected state by the scan electrode drive unit is controlled.
The potential difference between all the scan electrodes and all the data electrodes is temporarily set to be less than the threshold value.

In the display device of the present invention, the data electrode driving means temporarily connects all the scanning electrodes and all the data electrodes by setting the potential of the data electrodes to the potential in the non-selected state of the data electrodes. The potential difference between them is less than the threshold.

Further, in the display device of the present invention, the data electrode driving means may include, for example, all the scanning electrode temporarily after the scanning electrode selected by the scanning electrode driving means is switched by the scanning electrode driving means. In order to make the potential difference between the data electrodes and all the data electrodes less than the threshold value, all the data electrodes are set to the non-selected state for a predetermined period.

In the display device of the present invention, for example, the data electrode driving means temporarily connects all the scanning electrodes and all the data electrodes before switching the scanning electrode selected by the scanning electrode driving means. In order to make the potential difference between the data electrodes less than the threshold value, all data electrodes are set to the non-selected state only for a predetermined period.

In the display device according to the present invention, the data electrode driving means temporarily connects all the scanning electrodes before and after the switching of the scanning electrode selected by the scanning electrode driving means, for example. In order to make the potential difference between all the data electrodes less than the threshold value, all the data electrodes are set to the non-selected state for a predetermined period.

In the display device of the present invention, for example, the data electrode driving means supplies a constant current to the data electrode in a selected state, and applies a predetermined potential to the data electrode in a non-selected state.

Further, in the display device of the present invention, the light emitting element is, for example, an organic electroluminescent element.

[0071]

Embodiments of the present invention will be described below in detail with reference to the drawings. [First Embodiment] FIG. 1 is a circuit diagram showing a configuration of a main part of a display device according to a first embodiment of the present invention. The display device according to the present embodiment includes an organic EL display 1, a scan electrode drive unit 2, and a data electrode drive unit 3. In the present embodiment, the display 1 has a matrix electrode configuration and is driven by a dynamic driving method. Further, in the present embodiment, the electron injection electrode is driven as a scanning electrode, and the hole injection electrode is driven as a data electrode. The organic EL display 1 corresponds to the display of the present invention, the scan electrode driver 2 corresponds to the scan electrode driver of the present invention, and the data electrode driver 3 corresponds to the data electrode driver of the present invention.

The organic EL display 1 includes scanning electrodes COM1 to COMn and data electrodes S arranged in a matrix.
And EG1～SEGm, the scanning electrodes and the data electrodes are formed at the intersection, the organic EL element EL _1,1 ~EL m as a plurality of light emitting elements connected to the electrodes, and a _n. The organic EL element emits light when the potential difference between the scanning electrode and the data electrode connected to the organic EL element is equal to or greater than a predetermined threshold. Note that the code COMx (x = 1 to
n) represents a scan electrode on the x-th row, and is denoted by SEGy (y =
1 to m) represent the scanning electrodes in the y-th column,
_{x and y} represent the organic EL elements in the x-th row and the y-th column. When the organic EL element is represented by an equivalent electric circuit, FIG.
become that way.

The scanning electrode driving section 2 is connected to the scanning electrodes COM1 to COMn of the display 1 and scan electrodes COM1 to COMn.
The scan electrode COM1 is set so that OMn is sequentially selected.
~ COMn. The data electrode driving unit 3 is connected to the data electrodes SEG1 to SEGm of the display 1 and arbitrarily connects the data electrodes SEG1 to SEGm.
The data electrode SE is set to a selected state for supplying a constant current.
G1 to SEGm are driven.

The scan electrode driving section 2 includes n switches SW
And a ₁ 1 ~SW1 _n. Each switch SW1 _{1 to} SW
The 1 _n movable contacts are respectively connected to the scan electrodes COM1 to CO
Mn. While the fixed contact power supply voltage V of the two fixed contacts of the switches SW1 ₁ ~SW1 _n
cc is applied. Ground potential is applied to the other fixed contact of the switch SW1 ₁ ~SW1 _n. The scan electrode drive unit 2 connects a movable contact of a switch to a fixed contact on the ground potential side, applies a ground potential to a scan electrode connected to the switch, and sets the scan electrode to a selected state. Also, the scan electrode driving unit 2 connects the movable contact of the other switch to the fixed contact on the power supply voltage Vcc side, so that the scan electrode connected to the other switch has the power supply voltage V
By applying cc, the scanning electrode is brought into a non-selected state. Scan electrode driver 2, such an operation, the switch SW1 ₁
To the switch SW1 _n to perform line-sequential driving.

The data electrode driving section 3 includes m switches S
W2 _{1 to} SW2 _m . Each switch SW2 ₁ ~S
The movable contacts of W2 _m are connected to the data electrodes SEG _{1 to} SEG, respectively.
Connected to EG _m . Each switch SW2 ₁ ~SW2 _m
One end of each of the constant current sources I1 to Im is connected to one of the two fixed contacts. The other ends of the constant current sources I1 to Im are grounded via a voltage source 4 of a power supply voltage Vcc. Other fixed contact of the switch SW2 ₁ ~SW2 _m is grounded. Data electrode driver 3
In synchronism with the operation of the switch SW1 ₁ ~SW1 _n of the scan electrode driving unit 2 operates the switch SW2 ₁ ~SW2 _m,
When a certain scanning electrode is in the selected state, a desired potential other than the ground potential is applied to the desired data electrode by connecting the desired data electrode to the constant current source, thereby setting the selected data electrode to the selected state. Further, the data electrode driving section 3 applies a ground potential to the data electrodes by grounding the data electrodes other than the data electrodes to be selected, thereby setting the data electrodes to a non-selected state. The potential applied to the data electrode in the selected state is a potential of such a magnitude that the potential difference between the data electrode in the selected state and the scanning electrode in the selected state is equal to or larger than a threshold value. As a result, a potential difference equal to or greater than a threshold is applied between the selected scan electrode and the selected data electrode, and a constant current is applied to the organic EL element connected to the selected scan electrode and the selected data electrode. And the organic EL element emits light.

The scan electrode driver 2 applies the power supply voltage Vcc to the scan electrodes in the non-selected state. In addition, the data electrode driving unit 3 applies the ground potential (0
V). This prevents erroneous light emission due to current sneak.

FIG. 2 is a block diagram showing an example of the overall configuration of the display device according to the present embodiment. The display device according to the present embodiment includes an organic EL display 1, a scan electrode driver 2, and a data electrode driver 3 as well as an organic EL display 1.
And a main control unit 4 for outputting data to be displayed and data relating to display, and a scan electrode which is a signal for driving a scan electrode of the organic EL display 1 in accordance with the display data given from the main control unit 4. A drive signal and a data electrode drive signal that is a signal for driving the data electrode of the organic EL display 1 are generated, a scan electrode drive signal is output to the scan electrode drive unit 2, and the data electrode drive signal is converted to the data electrode drive signal. A display control unit 5 for outputting to the unit 3, and connected to the display control unit 5,
A display data storage unit 6 for storing data necessary for expanding display data provided from the main control unit 4 and the like into matrix data, bitmap data, and the like, data of predetermined display contents, and the like is provided. .

The main control unit 4 supplies display data to be displayed on the organic EL display 1 to the display control unit 5, specifies display data stored in the display data storage unit 6, and controls timing required for display. And control data to the display control unit 5. The main control unit 4 generally includes a general-purpose MPU (microprocessor) and a control algorithm or the like stored in a storage medium (ROM (read only memory), RAM (random access memory), or the like) connected to the MPU. It can be realized by. The main control unit 4
As for CISC (Co
mplex Instruction Set Computer), RISC (Reduce
d Instruction Set Computer), DSP (Digital Sign)
al Processor) can be used. In addition, the main control unit 4 may further include an ASIC (Applicat
ion specified integrated circuit) or a combination of logic circuits. In FIG. 2, the main control unit 4 is provided independently, but the main control unit 4 is
It may be integrated with the display control unit 5 or the control unit of the device provided with the display 1.

The display control unit 5 analyzes display data and the like provided from the main control unit 4 and the like, searches display data stored in the display data storage unit 6 as necessary, and stores the display data. It is converted into matrix data or the like to be displayed at a predetermined position on the organic EL display 1. That is, the display control unit 5 sets the data of the image (image or character) to be displayed as dots (pixels) given to the intersections of the respective matrices in the organic EL display 1, that is, dot data in units of organic EL elements. Then, a signal for driving the scanning electrode and the data electrode corresponding to the coordinates of the dot to be displayed is generated. The display control unit 5
Performs control of driving in units of frames, control of the driving ratio (duty) between the scanning electrodes and the data electrodes, and the like.

The display control unit 5 exchanges data with, for example, a control circuit using a processor or a complex logic circuit having a predetermined arithmetic function, and this control circuit exchanges data with the external main control unit 4 and the like. Timing signal generation circuit (oscillation circuit) that supplies a timing signal, a display timing signal, a read / write timing signal to an external storage device, and the like to a buffer memory and a control circuit used at that time.
And a storage device control circuit for exchanging display data and the like with the external storage device, and display data read from the external storage device or provided externally, or obtained by processing such display data. It is composed of a drive signal transmitting circuit for generating and transmitting a drive signal based on the received display data, and various registers for storing data relating to a display function and a display to be displayed, control commands, and the like provided from outside. be able to.

The display data storage unit 6 stores, for example, data (conversion table) necessary for developing externally applied image data into matrix data on the display 1,
Reading and writing can be performed by storing predetermined character data and matrix data in which image data is expanded, and specifying the storage position (address) of each data as needed. As such a display data storage unit 6, a RAM (for example, V (video)
Although it is preferable to use a semiconductor storage element such as a RAM (RAM) and a ROM, the present invention is not limited to this, and a storage medium using light or magnetism may be used.

The scan electrode driver 2 and the data electrode driver 3 drive the scan electrode and the data electrode in accordance with the scan electrode drive signal and the data electrode drive signal provided from the display controller 5, respectively. The organic EL element constituting the organic EL display 1 is a light emitting element that emits light by current driving.
Therefore, the scanning electrode driving unit 2 and the data electrode driving unit 3
In other types of display devices, a scan electrode drive signal and a data electrode drive signal, which are usually given as voltage signals,
The signal is converted into a signal of a predetermined current value, and this is converted to a predetermined scanning electrode,
The scanning electrode and the data electrode are driven by applying the data to the data electrode. The magnitude of the driving current is usually about 0.001 to 1 mA on the data side, and about 0.001 mA on the scanning side.
It is about 1 to 300 mA.

More specifically, the scan electrode driving unit 2 and the data electrode driving unit 3 are provided with a predetermined voltage using a voltage-current conversion element or an amplification element (power amplification) having a required current capacity. The scanning electrode and the data electrode at the position are driven. Such a driving circuit can be configured using a push-pull circuit or the like.

The data electrode drive section 3 needs to be provided with a constant current source in order to drive the data electrodes with current. This constant current source can be generally configured using a current mirror circuit or the like. In order to drive the current mirror circuit with a constant current, it is necessary to drive the current mirror circuit with a voltage higher than the voltage applied to the load. The load referred to here is a combined resistance such as the resistance of the organic EL element, the wiring resistance, and the ON resistance of the switch during light emission.

A contact device such as a relay may be used as the voltage-current conversion element or the amplifying element. However, in consideration of high-speed operation and reliability, a transistor, an FET (field-effect transistor), A semiconductor element having the same function as that described above is preferable. Further, these semiconductor elements may be integrated circuits. When these semiconductor elements are used, a scan electrode and a data electrode are connected to either the power supply side or the ground side of the semiconductor element. Here, connecting to the power supply side and the grounding side means connecting directly to a voltage source, a current source, and a grounding line, as well as connecting via elements such as a current limiting resistor, a protection device, and a regulator. The case is also included.

In the organic EL display 1, a plurality of scanning electrodes and a plurality of data electrodes are arranged so as to intersect with each other, and a specific driving signal connected to these two electrodes is provided by a drive signal applied between any two electrodes. Pixels (organic EL elements) emit light. The number of scanning electrodes and the number of data electrodes of the display 1 are appropriately determined depending on the size and definition of the display 1, but usually the number of scanning electrodes is 1 to 768 and the number of data electrodes is about 1 to 3072. .

The circuit configuration as described above uses an organic EL
This is merely an example of a circuit configuration for driving the display 1, and other circuit configurations may 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 completely integrated without being clearly divided. Note that the circuit device as described above is usually composed of one or more ICs.
And its peripheral parts.

Next, the operation of the characteristic portion of the display device according to the present embodiment will be described with reference to FIGS.

In the conventional driving method as shown in FIG. 22, when the scan electrode to be selected is switched, the charge storage state of the capacity of the organic EL element connected to each data electrode differs depending on the data electrode. . For this reason, a difference occurs in the path of current flow depending on the data electrode. As a result, a difference occurs in a rise in voltage depending on the data electrode, and a difference occurs in light emission luminance depending on the organic EL element.

In the present embodiment, when the scanning electrode to be switched to the selected state is switched, the charge accumulation state of the capacitance of the organic EL element connected to each data electrode is made the same for all the data electrodes. The path of current flow in the data electrode is made the same. Thus, the rise of the voltage is the same for all the data electrodes, and the difference in luminance between the organic EL elements can be eliminated, and all the organic EL elements can be made to emit light uniformly.

In the present embodiment, when the scanning electrodes to be switched to the selected state are switched, in order to make the charge accumulation state of the capacitance of the organic EL element connected to each data electrode the same, the selection state is changed. By controlling the potential of the data electrode when the scan electrode is switched, the potential difference between all the scan electrodes and all the data electrodes is temporarily reduced to less than the threshold value. In the present embodiment, when the scan electrodes to be switched to the selected state are switched, by setting all the data electrodes to the non-selection state only for a predetermined period, the time between all the scan electrodes and all the data electrodes is temporarily reduced. Is less than the threshold value. Hereinafter, a period in which all the data electrodes are in the non-selection state when the scanning electrode in the selection state is switched is referred to as an all data electrode non-selection period.

Here, the all data electrode non-selection period may be provided after the selected scan electrode is switched, may be provided before the selected scan electrode is switched, or may be provided in the selected state. May be provided both after and after the scan electrode is switched. That is, it is sufficient that there is a period in which all data electrodes are in a non-selected state between the time when a certain scan electrode is driven and the time when the next scan electrode is driven. The present embodiment is an example in which the all data electrode non-selection period is provided after the scanning electrode to be selected is switched.

In the all data electrode non-selection period, the data electrode driving section 3 applies a ground potential (0 V), which is a potential at the time of non-selection, to each data electrode. Such a non-selection period for all data electrodes is preferably set when the display control unit 5 generates a drive signal for the scan electrode and a drive signal for the data electrode.

In the following, the case where the organic EL elements EL _1,1 , EL _1,2 , EL _2,2 emit light, focusing on the scanning electrodes COM1, COM2 and the data electrodes SEG1, SEG2, will be described as an example.

FIG. 3 shows an example of a change in the state of the scan electrode and the data electrode in the present embodiment. In this figure, (a) shows a change in the voltage of the scan electrode COM1, (b) shows a change in the voltage of the scan electrode COM2, (c) shows a change in the voltage of the data electrode SEG1, and (d) shows The change of the voltage of the data electrode SEG2 is shown. The voltages of the scan electrodes COM1 and COM2 are at a low level in the selected state, and the data electrodes SEG1 and SE2
The voltage of G2 is at a high level in the selected state. In this example, first, the scanning electrode COM1 is in the selected state, and at this time, the data electrode SEG1 is in the selected state,
Data electrode SEG2 is in a non-selected state. Next, the scan electrode COM2 is selected, and at this time, the data electrode S
EG1 and data electrode SEG2 are both selected. In the present embodiment, as shown in (c) and (d),
After the switching of the scanning electrode in the selected state, an all data electrode non-selection period T is provided. As a result, the rise of the voltage of the data electrodes SEG1 and SEG2 is similar.

FIG. 4 shows the state of the organic EL element when the scanning electrode COM1 is in the selected state. In this figure, for the organic EL element, attention is paid only to the capacitance component.
One end is connected to the scanning electrode, and the other end is represented as a capacitor connected to the data electrode. As shown in this figure, when the scan electrode COM1 is in the selected state, the data electrode SEG1 is in the selected state, and the scan electrode COM1 is in the selected state.
EL element EL at the intersection of data electrode SEG1
₁ , ₁ emits light because it is biased in the forward direction. Another organic EL element E connected to the data electrode SEG1
Since the power supply voltage Vcc is applied to the corresponding scan electrodes, no charge is accumulated in the capacitors C _{1,2 to} C _{1, n} for L _{1,2 to} EL _{1, n} .

FIG. 5 shows that the selected scanning electrode is the scanning electrode C.
FIG. 9 shows a transient current flow in all data electrode non-selection periods T after changing from OM1 to scan electrode COM2. Also in this figure, the organic EL element is represented as a capacitor. As shown in this figure, in the all data electrode non-selection period T, the ground potential is applied to all the data electrodes. Organic EL element EL _{1,3 to} EL _{1, n} capacitance C _1,3 to
At C _{1, n} , no charge is accumulated in the state of FIG. 4, and therefore, at the moment when the data electrode SEG1 becomes the ground potential, as shown by the arrow in FIG. A current for accumulating electric charges flows in the direction. Also,
In the capacitance C _{1, 1} of the organic EL element EL _{1, 1,} since the charge in the forward direction of the organic EL device has been stored in the state of FIG. 4, it discharges its charge, yet the charge in the opposite direction of the organic EL device The current for accumulating the current flows. Organic EL element EL
_In the capacitance C _1,2 of _1,2 , a current flows from the capacitance of another organic EL element connected to the data electrode SEG1 in the forward direction of the organic EL element.

[0098] On the other hand, the capacitance C _2,1 of the organic EL element EL _2,1, since a state where no charge is stored in the state of FIG. 4, as shown in FIG. 5, the application of the scan electrode COM1 When the potential is switched to the power supply voltage Vcc, the organic E
A current for accumulating electric charges flows in the reverse direction of the L element.

After a certain period of time, the above transient current stops flowing, and the organic EL element enters a stable state in which electric charges are accumulated in the capacitor as shown in FIG. At this time, the charge storage state of the capacitance of all the organic EL elements connected to the data electrode SEG1 is changed to the data electrode SEG1.
This is the same as the charge storage state of the capacitance of all the organic EL elements connected to No. 2.

FIG. 6 shows a current flow when the data electrodes SEG1 and SEG2 are in the selected state after the entire data electrode non-selection period T. In this figure, the organic E
The L element is represented as a capacitor. As shown in this figure, when the data electrodes SEG1 and SEG2 are in the selected state, the rise of the voltage of the data electrodes SEG1 and SEG2 becomes almost the same. Therefore, the organic EL element EL
_1,2 and EL _2,2 have no luminance difference.

In the present embodiment, the time of the entire data electrode non-selection period T is usually about 10 ns to 1 ms, and preferably about 1 μs to 100 μs. In the above description, the data electrode is set to the non-selection state, and the data electrode is set to the selection state after a stable state in which no current flows through the capacitance of the organic EL element. If the level does not cause a problem, the entire data electrode non-selection period may be set so that the data electrodes are brought into the selected state before the stable state is attained.

As described above, according to the present embodiment, when the scanning electrode to be selected is switched, the entire data electrode non-selection period is set, and during this all data electrode non-selection period, Since the data electrodes of
When the scanning electrodes to be switched to the selected state are switched, the charge accumulation state of the capacity of the organic EL element connected to each data electrode can be made the same for all the data electrodes, and only the driving signal of the data electrode is devised. With a simple configuration, it is possible to prevent a difference in luminance between pixels from occurring depending on a light emission pattern.

The display device according to the present embodiment is, for example,
Indicators in home appliances such as microwave ovens, electric rice cookers, air conditioners, video equipment, audio equipment,
It is suitably used for various indicators such as a speedometer, a tachometer, and a navigation system in automobiles and motorcycles, and various instruments used in various aircraft and control facilities.

[Second Embodiment] Next, a display device according to a second embodiment of the present invention will be described with reference to FIGS. In the present embodiment, when the scan electrodes to be switched to the selected state are switched, all the data electrodes are not selected in order to make the charge accumulation state of the capacity of the organic EL element connected to each data electrode the same for all the data electrodes. This is an example in which the period is provided before the scanning electrode to be selected is switched.

Hereinafter, similarly to the first embodiment, scan electrodes COM1, COM2 and data electrodes SEG1, SEG2 are provided.
Focusing on G2, the organic EL elements EL _1,1 , EL _1,2 , EL
_The case where ₂ and ₂ emit light will be described as an example.

FIG. 7 shows an example of changes in the states of the scanning electrodes and the data electrodes in the present embodiment. In this figure, (a) shows a change in the voltage of the scan electrode COM1, (b) shows a change in the voltage of the scan electrode COM2, (c) shows a change in the voltage of the data electrode SEG1, and (d) shows The change of the voltage of the data electrode SEG2 is shown. In the present embodiment, as shown in (c) and (d), the all data electrode non-selection period T is provided immediately before the scan electrode to be switched to the selected state is switched. As a result, the rise of the voltage of the data electrodes SEG1 and SEG2 is similar.

FIG. 8 shows the state of the organic EL element when the scanning electrode COM1 is in the selected state. In this figure, for the organic EL element, attention is paid only to the capacitance component.
One end is connected to the scanning electrode, and the other end is represented as a capacitor connected to the data electrode. As shown in this figure, when the scan electrode COM1 is in the selected state, the data electrode SEG1 is in the selected state, and the scan electrode COM1 is in the selected state.
EL element EL at the intersection of data electrode SEG1
₁ , ₁ emits light because it is biased in the forward direction. Another organic EL element E connected to the data electrode SEG1
Since the power supply voltage Vcc is applied to the corresponding scan electrodes, no charge is accumulated in the capacitors C _{1,2 to} C _{1, n} for L _{1,2 to} EL _{1, n} .

FIG. 9 shows that the selected scanning electrode is the scanning electrode C.
It shows a transient current flow in all data electrode non-selection periods T immediately before changing from OM1 to scan electrode COM2. Also in this figure, the organic EL element is represented as a capacitor. As shown in this figure, in the all data electrode non-selection period T, the ground potential is applied to all the data electrodes. Capacities C _{1,2 of} organic EL elements EL _{1,2 to} EL _{1, n}
In -C 1, _n, since a state where no charge is stored in the state of FIG. 8, at the moment the data electrodes SEG1 becomes ground potential, as indicated by arrows in the figure, the organic EL device A current for accumulating charges flows in the opposite direction. In the capacitance C _{1, 1} of the organic EL element EL _{1, 1,} since the charge in the forward direction in a state of FIG. 8 have been accumulated, the moment the data electrodes SEG1 becomes ground potential, for discharging the charges Current flows in the opposite direction of the organic EL element. In addition, the capacitance C _1,1 of the organic EL element EL _1,1 has the organic EL element E in the forward direction.
L _{1, 2} ~EL _{1, n} current from capacitor C _1,2 ~C _{1, n} of flows. There is no change in the data electrode SEG2.

After a certain period of time, the above transient current stops flowing, and the organic EL element enters a stable state in which electric charges are accumulated in the capacitance as shown in FIG. At this time, the organic EL connected to the data electrode SEG1
The charge storage state of the capacitor of the element is the same as the charge storage state of the capacitor of the organic EL element connected to the data electrode SEG2.

FIG. 10 shows the flow of current when the data electrodes SEG1 and SEG2 are in the selected state after the entire data electrode non-selection period T. Also in this figure, the organic EL element is represented as a capacitor. As shown in this figure, when the data electrodes SEG1 and SEG2 are in the selected state, the rise of the voltage of the data electrodes SEG1 and SEG2 becomes almost the same. Therefore, the organic EL element EL
_1,2 and EL _2,2 have no luminance difference.

The other configurations, operations and effects of the present embodiment are the same as those of the first embodiment.

As described in Japanese Patent Application Laid-Open No. 9-232074, when a reset period is provided for driving the scan electrodes, a large rush current flows in the scan current. Become. On the other hand, according to the first and second embodiments of the present invention, it is not necessary to take measures against the inrush current. Hereinafter, this will be described in detail.

First, as in the first embodiment, when the all data electrode non-selection period is provided after the scanning electrode to be selected is switched, as shown in FIG. When is selected, current flows only into the element that emits light from the constant current source connected to the element, so that there is no need to take measures against inrush current in the scan electrode.

When the all data electrode non-selection period is provided before the switching of the selected scanning electrode as in the second embodiment, as shown in FIG. When is selected, current flows not only from the constant current source connected to the element to emit light but also from the voltage source connected to the scanning electrode immediately before the element to emit light. However, the current flowing from the voltage source connected to the scan electrode immediately before the element to emit light, when a reset period is provided for driving the scan electrode, all other than the scan electrode to which the element to emit light is connected Is very small as compared with the current flowing from the voltage source connected to the scan electrode. For example, if there are 100 scanning electrodes, the former becomes 1/99 of the latter. Therefore, there is no need to take measures against inrush current in the scanning electrodes.

As described above, according to the present embodiment, it is not necessary to take measures against the rush current on the scanning electrodes.
The circuit of the scan electrode drive unit 2 does not become complicated or large.

Next, an example of the configuration of an organic EL display used in the display device according to the first embodiment and the second embodiment will be described with reference to FIG. FIG.
FIG. 3 is an explanatory diagram showing an example of a configuration of an organic EL display.
The organic EL display 1 in this example includes a hole injection electrode (data electrode) 1 arranged in a matrix on a substrate 11.
An organic layer containing at least an organic substance involved in a light emitting function is provided between the electron injection electrode 2 and the electron injection electrode (scanning electrode) 16. Explaining in detail, the organic EL display 1
For example, between the hole injection electrode 12 and the electron injection electrode 16, the hole injection transport layer 13, the light emitting layer 14, and the electron injection transport layer 1, which are organic layers, are arranged in this order from the hole injection electrode 12 side.
5, a protective layer is further laminated as required, and a sealing plate such as glass is further disposed thereon. The organic EL element is formed at the intersection of the hole injection electrode 12 and the electron injection electrode 16.

The light emitting layer 14 has a function of injecting holes (holes) and electrons, a function of transporting them, 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 14.

The hole injection / transport layer 13 has a function of facilitating the injection of holes from the hole injection electrode 12, a function of stably transporting holes, and a function of hindering electrons. The electron injection transport layer 15 has a function of facilitating the injection of electrons from the electron injection electrode 16, a function of stably transporting electrons, and a function of preventing holes. These layers increase and confine holes and electrons injected into the light emitting layer, optimize the recombination region, and improve luminous efficiency.

The thickness of the light emitting layer, the thickness of the hole injecting and transporting layer 13 and the thickness of the electron injecting and transporting layer 15 are not particularly limited and vary depending on the forming method.
The thickness is about 500 nm, and particularly preferably 10 to 300 nm.

The thickness of the hole injecting and transporting layer 13 and the thickness of the electron injecting and transporting layer 15 depend on the design of the recombination / light emitting region, but may be about the same as the thickness of the light emitting layer or about 1/10 to 10 times the thickness. I just need. When the hole or electron injection layer and the transport layer are separated from each other, it is preferable that the injection layer has a thickness of 1 nm or more and the transport layer has a thickness of 1 nm or more. The injection layer at this time,
The upper limit of the thickness of the transport layer is usually about 500 nm for the injection layer and about 500 nm for the transport layer. The same applies to the case where two injection / transport layers are provided.

The light emitting layer 14 of the organic EL element contains a fluorescent substance which is a compound having a light emitting function. Examples of such a fluorescent substance include, for example, JP-A-63-264.
No. 692, for example, at least one compound selected from compounds such as quinacridone, rubrene, and styryl dyes. Examples of the fluorescent substance include a quinoline derivative such as a metal complex dye having 8-quinolinol or a derivative thereof as a ligand, such as tris (8-quinolinolato) aluminum, tetraphenylbutadiene, anthracene, perylene, coronene, and 12-quinolinol.
A phthaloperinone derivative is also included. Further, as a fluorescent substance, JP-A-8-12600 (Japanese Patent Application No.
Phenylanthracene derivatives described in JP-A-8-12969 (Japanese Patent Application No. 6-1144).
No. 56) can be used.

The light emitting layer 14 is preferably used in combination with a host substance capable of emitting light by itself, and is also preferably used as a dopant. In such a case, the content of the compound in the light emitting layer is preferably 0.01 to 20% by weight, particularly preferably 0.1 to 15% by weight.
By using the light emitting layer 14 in combination with a host material, the emission wavelength characteristics of the host material can be changed, light emission shifted to a longer wavelength can be performed, and the light emission efficiency and stability of the device can be improved.

The host substance is preferably a quinolinolato complex, and more preferably an aluminum complex having 8-quinolinol or a derivative thereof as a ligand. Such an aluminum complex is disclosed in, for example, JP-A-63-264692.
JP-A-3-255190, JP-A-5-70733
JP-A-5-258859, JP-A-6-21587
No. 4 and the like.

As the host substance, specifically, first,
Tris (8-quinolinolato) aluminum, bis (8-
Quinolinolato) magnesium, bis [benzo (f) -8
-Quinolinolato] zinc, bis (2-methyl-8-quinolinolato) aluminum oxide, tris (8-quinolinolato) indium, tris (5-methyl-8-quinolinolato) aluminum, 8-quinolinolatolithium, tris (5-chloro) -8-quinolinolato) gallium, bis (5-chloro-8-quinolinolato) calcium, 5,7
-Dichloro-8-quinolinolatoaluminum, tris (5,7-dibromo-8-hydroxyquinolinolato) aluminum, poly [zinc (II) -bis (8-hydroxy-5-quinolinyl) methane] and the like.

[0125] Other host materials include those disclosed in
No. 12600 (Japanese Patent Application No. 6-110569) and phenylanthracene derivatives described in JP-A-8-12969.
Also preferred are tetraarylethene derivatives described in Japanese Patent Application Laid-Open (JP-A-Heisei 6-114456).

The light emitting layer 14 may also serve as the electron injecting / transporting layer 15. In such a case, the tris (8-
It is preferable to use (quinolinolato) aluminum or the like. In this case, these fluorescent substances may be deposited to form a light emitting layer.

The light emitting layer 14 is preferably a mixed layer of at least one kind of hole injecting and transporting compound and at least one kind of electron injecting and transporting compound, if necessary. Preferably contains a dopant. The content of the compound in such a mixed layer is 0.01 to 20% by weight, more preferably 0.1 to 15% by weight.
It is preferable that

In such a mixed layer, a carrier hopping conduction path is formed, so that each carrier moves in a material having a favorable polarity, and injection of a carrier having the opposite polarity is unlikely to occur. Therefore, there is an advantage that the organic compound is less likely to be damaged, and the life of the device is extended. Further, by including the above-mentioned dopant in such a mixed layer, the emission wavelength characteristics of the mixed layer itself can be changed, the emission wavelength can be shifted to a longer wavelength, and the emission intensity is increased, The stability of the device can be improved.

The hole injecting / transporting compound and the electron injecting / transporting compound used in the mixed layer may be selected from a compound for the hole injecting / transporting layer and a compound for the electron injecting / transporting layer described later. Among them, as compounds for the hole injection transport layer, amine derivatives having strong fluorescence,
For example, it is preferable to use a triphenyldiamine derivative which is a hole transport material, a styrylamine derivative, or an amine derivative having an aromatic condensed ring.

As the compound capable of injecting and transporting electrons, it is preferable to use a quinoline derivative, furthermore a metal complex having 8-quinolinol or a derivative thereof as a ligand, particularly tris (8-quinolinolato) aluminum (Alq ₃ ). It is also preferable to use the above-mentioned phenylanthracene derivative and tetraarylethene derivative as the electron injecting and transporting compound.

Examples of the compound for the hole injecting and transporting layer include amine derivatives having strong fluorescence, such as the above-described hole transporting materials such as triphenyldiamine derivative, styrylamine derivative, and amine derivative having an aromatic condensed ring. It is preferably used.

The mixing ratio in this case depends on the respective carrier mobilities and carrier concentrations. In general, the weight ratio of the compound of the hole injecting / transporting compound / the compound having the electron injecting / transporting function is 1/99 to less. It is preferably about 99/1, more preferably about 10/90 to 90/10, and particularly preferably about 20/80 to 80/20.

The thickness of the mixed layer is preferably not less than the thickness corresponding to one molecular layer and less than the thickness of the organic compound layer. Specifically, the thickness is preferably 1 to 100 nm, more preferably 5 to 60 nm, particularly preferably 5 to 50 nm.

As a method of forming the mixed layer, co-evaporation in which evaporation is performed from different evaporation sources is preferable. However, when the vapor pressures (evaporation temperatures) are approximately the same or very close, they are mixed in advance in the same evaporation board. Alternatively, it can be deposited. In the mixed layer, it is preferable that the compounds are uniformly mixed, but in some cases, the compounds may exist in an island shape. The light-emitting layer is generally formed to a predetermined thickness by vapor-depositing an organic fluorescent substance or by dispersing and coating the resin in a resin binder.

The hole injecting and transporting layer 13 is formed, for example, in JP-A-63-295695 and JP-A-2-191694.
JP, JP-A-3-792, JP-A-5-2346
No. 81, JP-A-5-239455, JP-A-5
JP-A-299174, JP-A-7-126225, JP-A-7-126226, JP-A-8-100
Various organic compounds described in JP-A-172, EP0650955A1, and the like can be used. This organic compound is, for example, a tetraarylbendicine compound (triaryldiamine or triphenyldiamine: TP
D), aromatic tertiary amines, hydrazone derivatives, carbazole derivatives, triazole derivatives, imidazole derivatives, oxadiazole derivatives having an amino group, polythiophene and the like. These compounds may be used alone or in combination of two or more. When two or more kinds are used in combination, they may be stacked as separate layers or mixed.

When the hole injecting and transporting layer 13 is laminated separately into a hole injecting layer and a hole transporting layer, a preferable combination can be selected from the compounds for the hole injecting and transporting layer. At this time, a hole injection electrode (ITO)
Etc.) It is preferable to stack the compounds in the order from the 12th side in the order of the compounds having the lowest ionization potential. Further, it is preferable to use a compound having a good thin film property on the surface of the hole injection electrode. For such a stacking order, the hole injection transport layer 1
The same applies when two or more layers 3 are provided. With such a stacking order, the driving voltage is reduced, and the occurrence of current leakage and the occurrence and growth of dark spots can be prevented. In addition, when the device is formed, since evaporation is used, it is 1 to
Even a thin film having a thickness of about 10 nm can be made uniform and pinhole-free. Therefore, even if a compound having a small ionization potential in the hole injection layer and having absorption in the visible region is used, the color tone change of the emission color or re-absorption may occur. A decrease in efficiency can be prevented. The hole injecting and transporting layer 13 can be formed by vapor deposition of the above compound in the same manner as the light emitting layer and the like.

The electron injection / transport layer 15 has a tris (8-
Norinolat) aluminum (Alq _Three 8-kinori)
Organometallic complexes with phenol or its derivatives as ligands
Which quinoline derivatives, oxadiazole derivatives, peryl
Derivatives, pyridine derivatives, pyrimidine derivatives, quinoki
Sarin derivatives, diphenylquinone derivatives, nitro-substituted
A fluorene derivative or the like can be used. Electron injection transport
The layer 15 may also serve as the light emitting layer 14.
In the case of tris (8-quinolinolato) aluminum
It is preferable to use a memory or the like. Of the electron injection transport layer 15
The formation may be performed by vapor deposition or the like, similarly to the light emitting layer 14.

When the electron injecting and transporting layer 15 is laminated separately into an electron injecting layer and an electron transporting layer, a preferable combination can be selected from the compounds for the electron injecting and transporting layer. At this time, it is preferable to stack the compounds in descending order of the electron affinity value from the electron injection electrode side. Such a stacking order is the same when two or more electron injection / transport layers are provided.

The hole injection transport layer 13, the light emitting layer 14, and the electron injection transport layer 15 are preferably formed by a vacuum evaporation method since a uniform thin film can be formed. When a vacuum deposition method is used, a homogeneous thin film having an amorphous state or a crystal grain size of 0.2 μm or less can be obtained. When the crystal grain size exceeds 0.2 μm, the light emission becomes non-uniform, the driving voltage of the device must be increased, and the charge injection efficiency is significantly reduced.

The conditions for vacuum deposition are not particularly limited.
The degree of vacuum is 0 ^-4 Pa or less, and the deposition rate is 0.01 to 1 n.
It is preferable to be about m / sec. Further, it is preferable to form each layer continuously in a vacuum. If they are formed continuously in a vacuum, impurities can be prevented from adsorbing at the interface between the layers, so that high characteristics can be obtained. Further, the driving voltage of the element can be reduced, and the occurrence and growth of dark spots can be suppressed.

In the case where a plurality of compounds are contained in one layer when a vacuum evaporation method is used to form each of these layers, it is preferable to co-deposit each boat containing the compounds by individually controlling the temperature.

The electron injection / transport layer 15 and the hole injection / transport layer 13 may be inorganic layers using an inorganic material such as Si or Ge. The organic EL element has a functional thin film such as the hole injection electrode 12 and the electron injection electrode 16 formed so as to sandwich the organic layer on the substrate, in addition to the organic layer described above.

The electron injection electrode 16 is preferably made of a material having a low work function, for example, K, Li, Na, Mg, L
a, Ce, Ca, Sr, Ba, Al, Ag, In, S
It is preferable to use a single metal element such as n, Zn, or Zr, or a two-component or three-component alloy system containing them to improve stability. As an alloy system, for example, Ag · M
g (Ag: 0.1 to 50 at%), Al.Li (Li:
0.01-14 at%), In.Mg (Mg: 50-80)
at%), Al.Ca (Ca: 0.01 to 20 at%) and the like. Note that the electron injection electrode 16 can also be formed by a vapor deposition method or a sputtering method.

The thickness of the electron injecting electrode thin film may be a certain thickness or more so that electrons can be sufficiently injected.
5 nm or more, preferably 1 nm or more, more preferably 3 nm or more.
nm or more. Although the upper limit is not particularly limited, the film thickness may be usually about 3 to 500 nm. An auxiliary electrode or a protection electrode may be further provided on the electron injection electrode 16.

The pressure at the time of vapor deposition is preferably 1 × 10 ⁻⁸ to
At 1 × 10 ⁻⁵ Torr, the heating temperature of the evaporation source is preferably about 100 to 1400 ° C. for a metal material and about 100 to 500 ° C. for an organic material.

The hole injection electrode 12 is preferably a transparent or translucent electrode for extracting emitted light. ITO (tin-doped indium oxide), IZ
O (zinc-doped indium oxide), ZnO, SnO ₂ ,
In ₂ O _{3 and the} like can be mentioned, but ITO (tin-doped indium oxide) and IZO (zinc-doped indium oxide) are preferable. ITO is usually composed of In ₂ O ₃ and SnO
Is contained in a stoichiometric composition, but the amount of O may slightly deviate from this. The hole injection electrode 12 may be made of a known opaque metal material when transparency is not required.

The thickness of the hole injecting electrode 12 may be a certain thickness or more capable of sufficiently injecting holes, and is preferably in the range of 50 to 500 nm, more preferably 50 to 300 nm. The upper limit is not particularly limited, but if the thickness is too large, there is a fear of peeling or the like. On the other hand, if the thickness is too small, there is a problem in film strength, hole transport ability and resistance value at the time of production.

The hole injection electrode 12 can be formed by a vapor deposition method or the like, but is preferably formed by a sputtering method, particularly, a DC sputtering method.

The electrode on the side from which light is extracted has an emission wavelength band,
The light transmittance is usually 350 to 800 nm, particularly preferably 50% or more, particularly 60% or more, and more preferably 70% or more for each emitted light. Since the emitted light is extracted through the electrode on the light extraction side, if the transmittance is too low, the emission itself from the light emitting layer is attenuated, and the luminance required for the light emitting element tends not to be obtained.

After forming each layer of the organic EL structure, the Si
Inorganic materials O _X such as Teflon, a protective film may be formed using an organic material such as fluorocarbon polymers containing chlorine.
The protective film may be transparent or opaque, and the thickness of the protective film is about 50 to 1200 nm. The protective film, in addition to the reactive sputtering method, a general sputtering method, a vapor deposition method,
It may be formed by a PECVD (plasma CVD) method or the like.

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 organic EL element is driven by a direct current, a pulse, or the like, and can be driven by an alternating current. The voltage applied to the organic EL element is usually about 2 to 30 V.

[Third Embodiment] Next, a display device according to a third embodiment of the present invention will be described with reference to FIGS. FIG. 12 is a block diagram showing an example of the entire configuration of the display device according to the present embodiment.
The display device according to the present embodiment includes an organic EL display 31. The organic EL display 31 has the same configuration as that of the organic EL display 1 according to the first embodiment. Scan electrodes and data electrodes are arranged in a matrix, and these scan electrodes and data electrodes intersect. And an organic EL element as a plurality of light emitting elements connected to both electrodes. The organic EL element uses the organic E
Light is emitted when the potential difference between the scanning electrode and the data electrode connected to the L element is equal to or greater than a predetermined threshold. The organic EL display 31 corresponds to the display in the present invention.

The display device according to the present embodiment further includes a scan electrode drive circuit 32 for driving the scan electrodes of the organic EL display 31, and a data electrode drive section for driving the data electrodes of the organic EL display 31. 33, a main control unit 34 for outputting data to be displayed on the organic EL display 31 and data relating to display, and display timing and display of the organic EL display 31 in accordance with display data given from the main control unit 34. A display control unit 35 for controlling the size and the like; a display data storage unit 36 connected to the display control unit 35 for holding display data given from the main control unit 34; An oscillator 37 for generating a clock and supplying the clock to the main controller 34;
And an oscillator 38 for generating a clock used in the display control section 35 and supplying the generated clock to the display control section 35. The scan electrode drive circuit 32 corresponds to the scan electrode drive unit in the present invention, and the data electrode drive unit 33 corresponds to the data electrode drive unit in the present invention.

The scan electrode drive circuit 32 is connected to the scan electrodes of the organic EL display 31 via the connection section. In the present embodiment, the plurality of data electrodes are divided into four sets, and the data electrode drive unit 33 has four data electrode drive circuits 33A to 33D that drive each set of data electrodes. Each of the data electrode driving circuits 33A to 33D
Each is connected to each set of data electrodes via the connection portions 43A to 43D. Connecting parts 42, 43A to 43D
For example, a heat seal connector, a flexible board, or the like is used.

The configuration of scan electrode drive circuit 32 is the same as the configuration of scan electrode drive section 2 in the first embodiment. The configuration of the data electrode driving circuits 33A to 33D is the same as the configuration of the data electrode driving unit 3 in the first embodiment. Each of the driving circuits 32 and 33A to 33D
An FET or a bipolar transistor may be used as the switching element, and the switching element may be configured by a circuit having an open drain or open collector configuration, a push-pull circuit, or the like.

The main controller 34 and the display controller 35 are connected via a control bus 51, a data bus 52 and an address bus 53. The main control unit 34 and the display control unit 3
Reference numeral 5 is connected via a signal line 57 for transmitting a vertical scanning start signal from the display control unit 35 to the main control unit 34.
The vertical scanning start signal is a signal indicating the start of vertical scanning, that is, the timing of starting the display of the data of the first one line of the display data for one screen. Display control unit 35
And the display data storage unit 36 are connected via a control bus 54, a data bus 55, and an address bus 56.

The display control section 35 and each of the drive circuits 32 and 33
A to 33D and the main control unit 34 include the driving circuits 32, 33A to 33D and the main control unit 34 from the display control unit 35.
Connected via a signal line 58 for sending a latch pulse to the memory. The latch pulse is a signal that indicates the timing of switching the scanning electrodes to be in the selected state and displaying one line. The display control unit 35 and the driving circuits 32 and 33A to
33D is connected via a control bus 59. Also,
Display control unit 35 and data electrode driving circuits 33A to 33D
Are connected via a data bus 60. Note that the vertical scanning start signal is also transmitted by the control bus 59.

The main control unit 34 and the scan electrode drive circuit 32
The main controller 34 is connected to the scan electrode drive circuit 32 via a signal line 61 for sending a scan-side enable signal. The main control unit 34 and the data electrode driving circuits 33A to 33A
33D is a data electrode driving circuit 33A from the main control unit 34.
To 33D via a signal line 62 for transmitting a data-side enable signal.

The main control unit 34 gives the display control unit 35 control signals for inputting and outputting data via the control bus 51 and for instructing the display data storage unit 36 to operate. , And display data and instructions are sent via the data bus 52.

The display control unit 35 includes a display data storage unit 36
, A control signal via a control bus 54, address data via an address bus 56, and display data sent from the main control unit 34 via a data bus 55 to a display data storage unit 36. And display data is read from the display data storage unit 36.

Further, the display control section 35 controls the driving circuits 3
2, 33A to 33D are supplied with a control signal via a control bus 59 and a latch pulse via a signal line 58 to control each of the drive circuits 32, 33A to 33D and via a data bus 60. Data electrode drive circuit 3
The display data is transferred to 3A to 33D to control the display.

The specific means for realizing the main control unit 34, the display control unit 35, and the display data storage unit 36 are the main control unit 4, the display control unit 5, and the display data storage unit in the first embodiment. This is the same as in the case of No. 6. Also, the first
Similarly to the embodiment, the circuit configuration shown in FIG. 12 is merely an example of a circuit configuration for driving the organic EL display 31, and another circuit configuration having an equivalent function is employed. It is also possible.

FIG. 13 shows data electrode driving circuits 33A to 33A.
It is a block diagram showing an example of 3D composition. The data electrode driving circuits 33A to 33D include a data controller 71 for controlling input of display data, a bidirectional shift register 72 connected to the data controller 71, a latch 73 connected to the bidirectional shift register 72, A plurality of AND gates 74 having one input terminal connected to each output terminal of the latch 73; an output stage driver 75 connected to the output terminals of the plurality of AND gates 74; And a voltage controller 76 for controlling the One input terminal of the AND gate 74 is connected to the output terminal of the latch 73, and the other input terminal receives the data-side enable signal EN. The output terminal of the AND gate 74 is connected to the input terminal of the output stage driver 75.

In the data electrode driving circuits 33A to 33D, for example, 8-bit display data D0 to D7 input from the input terminals are input to the bidirectional shift register 72 via the data controller 71. The bidirectional shift register 72 shifts the input display data bit by bit in synchronization with, for example, a clock XSCL provided from the display control unit 35. Data in the bidirectional shift register 72 is sent to the latch 73. When the input of data to be displayed on one line in the horizontal direction of the organic EL display 31 into the bidirectional shift register 72 is completed, the data electrode driving circuit 3
3A to 33D, the display control unit 35 sends the latch pulse L
P is given. The latch 73 outputs the latch pulse LP
Is given, the held data is transferred to the AND gate 7
4 is output. AND gate 74 outputs data from latch 73 to output stage driver 75 when data-side enable signal EN is at a high level, and outputs data from latch 73 to output stage driver when data-side enable signal EN is at a low level. No output to 75. Output stage driver 7
5 is an organic EL display 3 based on the given data.
For example, 64-bit output signals OUT0 to OUT63 for driving one data electrode are output. Note that the voltage controller 76 is supplied with a high voltage VDDH and a ground level GND. Each part in the data electrode driving circuits 33A to 33D includes:
The power supply voltage Vcc is supplied.

Next, referring to the flow chart shown in FIG.
An example of a basic operation of the display device according to the present embodiment will be described.

In this operation, first, an initial setting of the main control unit 34 is performed (step S101). Next, the main control unit 34 specifies writing to an input / output (hereinafter, referred to as I / O) register of the display control unit 35 using the control bus 51 (step S102). Next, the main controller 34 uses the data bus 52 and the address bus 53 to write display setting information, such as the size and gradation of the display, into the control register of the display controller 35 (step S10).
3). Thereafter, the display control unit 35 controls the display of the organic EL display 31 according to the display setting information.

Next, the main control unit 34 instructs the display control unit 35 to write into the display data storage unit 36 using the control bus 51 (step S104). Next, the main control unit 34 transmits display data to the display control unit 35 using the data bus 52 and the address bus 53. Next, the display control unit 35 sets the display data storage unit 36 to the write mode using the control bus 54, and stores the display data sent from the main control unit 34 using the data bus 55 and the address bus 56. Write to the storage unit 36 (step S
105).

Next, the main control unit 34 specifies writing to the I / O register of the display control unit 35 using the control bus 51 (step S106). Next, the main control unit 34
Instructs the display control unit 35 to use the data bus 52 and the address bus 53 to specify the display start address of the display data. In response, the display control unit 35 sets the display data storage unit 36 to the read mode using the control bus 54, reads display data from the display data storage unit 36 using the data bus 55 and the address bus 56, and displays the display data. Display of data is started (step S107). Display control unit 3
5 controls the line-sequential scanning by the scan electrode side drive circuit 32 using the signal line 58 and the control bus 59, and controls the data electrode drive circuits 33A to 33D using the signal line 58, the control bus 59, and the data bus 60. By controlling, the display data is displayed on the organic EL display 31.

Next, the display control section 35 determines whether or not there is an interrupt request for writing new display data from the main control section 34 (step S108). If there is no interrupt request (N), the process returns to step S106,
Steps S106 and S107 are repeatedly executed. When there is an interrupt request (Step S108; Y), the display control unit 35 accepts an interrupt from the main control unit 34. In this case, step S10
4. As in step S105, the main control unit 34 instructs the display control unit 35 to write into the display data storage unit 36 (step S109), transmits the display data to the display control unit 35, and sends the display data to the display control unit 35. Sets the display data storage unit 36 to the write mode, and writes the display data sent from the main control unit 34 to the display data storage unit 36 (step S1).
10). Next, the process returns to step S106.

Next, the operation of the characteristic portion of the display device according to the present embodiment will be described with reference to FIG.

In the present embodiment, it is assumed that the potential difference between the data electrode and the scan electrode becomes equal to or larger than the threshold when the voltage of the scan electrode rises after the scan electrode shifts from the selected state to the non-selection period. To prevent this, the potential difference between all the scan electrodes and all the data electrodes is temporarily reduced to a value less than the threshold by controlling the potential of the data electrodes when the selected scan electrode is switched. I do. In the present embodiment, when the scan electrodes to be switched to the selected state are switched, by setting all the data electrodes to the non-selection state only for a predetermined period, the time between all the scan electrodes and all the data electrodes is temporarily reduced. Is less than the threshold value. Hereinafter, a period in which all the data electrodes are in the non-selection state when the scanning electrode in the selection state is switched is referred to as an all data electrode non-selection period.

Here, the all data electrode non-selection period may be provided after the selected scan electrode is switched, may be provided before the selected scan electrode is switched, or may be provided before the selected electrode is switched. May be provided both after and after the scan electrode is switched. That is, it is sufficient that there is a period in which all data electrodes are in a non-selected state between the time when a certain scan electrode is driven and the time when the next scan electrode is driven. The present embodiment is an example in which all data electrode non-selection periods are provided immediately before switching of the scanning electrodes to be in the selected state.

In the all data electrode non-selection period, the data electrode driving circuits 33A to 33D apply the ground potential (0 V), which is the potential at the time of non-selection, to each data electrode. In the present embodiment, all data electrode non-selection periods are set using the data side enable signal EN. That is, the main control unit 3
Reference numeral 4 denotes a data-side enable signal E for a certain period immediately before a selected scan electrode is switched with reference to a latch pulse input from the display control unit 35 as a timing reference.
N is set to low level. The period during which the data-side enable signal EN is at the low level is the all data electrode non-selection period. During data display, the data-side enable signal EN is at a high level during a period other than the all data electrode non-selection period. When the data-side enable signal EN becomes low level, the output of the latch 73 in FIG. 13 is not output to the output stage driver 75, so that the ground potential (0 V) is applied to the data electrode. As a result, the potential difference between all of the scan electrodes and all of the data electrodes temporarily becomes smaller than the threshold value before the selected scan electrode is switched.

FIG. 15 shows an example of a change in the state of the scan electrode voltage, the data electrode voltage, and the data side enable signal EN in the present embodiment. In this figure, (a) shows a change in voltage of an arbitrary scanning electrode (1), and (b) shows a scanning electrode (2) next to the scanning electrode (1).
(C) shows a change in the voltage of an arbitrary data electrode, and (d) shows a change in the data-side enable signal EN. In the example shown in FIG. 15, the rising waveform of the voltage of the scanning electrode and the rising waveform and falling waveform of the voltage of the data electrode are blunt.

In the example shown in FIG. 15, first, the scanning electrode (1) is in the selected state, and at this time, the data electrode is in the selected state. Next, the scanning electrode (2) is in a selected state,
At this time, in the example shown by the solid line in FIG. 15C, the data electrode is in a non-selected state. The data-side enable signal EN is at the low level only during the entire data electrode non-selection period T provided immediately before the scan electrode to be switched to the selected state, and is at the high level in other periods.

Hereinafter, in the present embodiment, description will be given of the fact that shadowing can be prevented from occurring by providing all data electrode non-selection period T immediately before switching of the scan electrode to be in the selected state.

In the present embodiment, the all data electrode non-selection period T is provided immediately before the switching of the selected scanning electrode is performed. The level temporarily goes low just before switching. Therefore, in the present embodiment, the following two aspects of the change in the voltage of the data electrode when the voltage of the scan electrode (1) rises after the scan electrode (1) shifts from the selected state to the non-selection period. There are two aspects. The first embodiment is shown in FIG.
As shown by the solid line in FIG. 5 (c), the voltage of the data electrode is maintained at a low level.
As shown by a broken line in FIG. 15C, the voltage of the data electrode rises.

In the first mode, since the voltage of the data electrode maintains the low level, after the scan electrode (1) shifts from the selected state to the non-selection period, the voltage between the data electrode and the scan electrode (1) is changed. The potential difference does not exceed the threshold, and the light emission luminance of the organic EL element does not increase.

In the second mode, both the voltage of the scan electrode (1) and the voltage of the data electrode rise. Therefore, in this case, the influence on the light emission luminance of the organic EL element differs depending on whether the rising waveform of the voltage of the scanning electrode (1) or the rising waveform of the voltage of the data electrode is steep.

When driving the data electrode with a constant current,
The rising waveform of the voltage of the data electrode is the scan electrode (1)
Does not become steeper than the rising waveform of the voltage. Therefore, in this case, the potential difference between the data electrode and the scan electrode (1) does not exceed the threshold after the scan electrode (1) shifts from the selected state to the non-selection period.
There is no increase in light emission luminance of the L element.

When driving the data electrode at a constant voltage,
The rising waveform of the voltage of the data electrode is the scan electrode (1)
Steeper than the rising waveform of the voltage. Therefore, in this case, even after the scan electrode (1) shifts from the selected state to the non-selection period, for a certain period, the potential difference between the data electrode and the scan electrode (1) becomes equal to or larger than the threshold value, Organic E
The L element may emit light. But even in that case,
The period during which the potential difference between the data electrode and the scanning electrode (1) is equal to or greater than the threshold value is extremely short, and the increase in light emission luminance of the organic EL element is extremely small.

As described above, in this embodiment, the potential difference between the data electrode and the scan electrode is prevented from exceeding the threshold after the scan electrode shifts from the selected state to the non-selection period. By the way, when the non-selection period for all data electrodes is not provided immediately before the switching of the scanning electrode to be in the selected state, the data electrode at the time of the rising of the voltage of the scanning electrode after the scanning electrode shifts from the selected state to the non-selection period. In addition to the above two aspects, there are two aspects of the voltage change: an aspect in which the voltage of the data electrode is maintained at a high level; and an aspect in which the voltage of the data electrode falls. As described above, these two aspects lead to an increase in light emission luminance of the organic EL element. In the present embodiment, there are no two modes that lead to an increase in light emission luminance of such an organic EL element.

Further, in the present embodiment, the potential difference between the data electrode and the scan electrode is prevented from exceeding the threshold value after the scan electrode shifts from the selected state to the non-selection period as described above. Therefore, even if the rising waveform of the voltage of the scanning electrode changes depending on the number of unselected data electrodes in an arbitrary scanning electrode, the light emission luminance of the organic EL element is hardly affected by the change.

As described above, according to the present embodiment, the entire data electrode non-selection period is provided immediately before the switching of the scanning electrode to be in the selected state, so that the scanning electrode shifts from the selected state to the non-selected period. After that, it is possible to prevent the potential difference between the data electrode and the scanning electrode from exceeding the threshold value. Therefore, according to the present embodiment, it is possible to prevent the occurrence of shadowing with a simple configuration in which the driving of the data electrode is devised.

In this embodiment, the threshold value, which is the minimum value of the potential difference between the data electrode and the scanning electrode required for the organic EL element to emit light, is, for example, 2V.
The time of the non-selection period is usually about 10 ns to 1 ms, and preferably about 1 μs to 100 μs.

When the display device according to the present embodiment was actually manufactured, a pattern as shown in FIG. 25 was displayed, and the luminance of the light emitting region 111 and the light emitting region 113 was measured using an optical measuring instrument. The difference in luminance between the light emitting region 111 and the light emitting region 113 was less than 5%. This luminance difference is within the range of the luminance difference where the luminance unevenness is not noticeable visually.

Other configurations, operations and effects of the present embodiment are the same as those of the first embodiment.

[Fourth Embodiment] Next, a display device according to a fourth embodiment of the present invention will be described with reference to FIG. This embodiment is an example in which the all data electrode non-selection period is provided immediately after the scan electrode to be selected is switched. The all data electrode non-selection period is set by setting the data-side enable signal to low level, as in the third embodiment.

FIG. 16 shows an example of a change in the state of the scan electrode voltage, the data electrode voltage, and the data side enable signal EN in this embodiment. In this figure, (a) shows a change in voltage of an arbitrary scanning electrode (1), and (b) shows a scanning electrode (2) next to the scanning electrode (1).
(C) shows a change in the voltage of an arbitrary data electrode, and (d) shows a change in the data-side enable signal EN. Note that in the example shown in FIG. 16, the rising waveform of the voltage of the scanning electrode and the rising waveform and falling waveform of the voltage of the data electrode are blunt.

In the example shown in FIG. 16, first, the scanning electrode (1) is in the selected state. At this time, in the example shown by the solid line in FIG. 16 (c), the data electrode is in the selected state.
Next, the scanning electrode (2) is in a selected state, and at this time, the data electrode is in a non-selected state. The data-side enable signal EN is at the low level only during the entire data electrode non-selection period T provided immediately after the switching of the selected scan electrode, and is at the high level in other periods. This allows
After the switching of the selected scanning electrode, the potential difference between all the scanning electrodes and all the data electrodes temporarily becomes smaller than the threshold value.

Hereinafter, in the present embodiment, it will be described that shadowing can be prevented from occurring by providing an all data electrode non-selection period T immediately after switching of the selected scanning electrode.

In the present embodiment, the all data electrode non-selection period T is provided immediately after the switching of the selected scanning electrode, so that the voltages of all the data electrodes are set to the selected scanning electrode. Becomes low level immediately after the switch. Therefore, in the present embodiment, the scanning electrode (1)
There are two modes for changing the voltage of the data electrode when the voltage of the scan electrode (1) rises after the transition from the selected state to the non-selection period. The first mode is a mode in which the voltage of the data electrode falls as indicated by a solid line in FIG. 16C, and the second mode is a mode in which the data is reduced as indicated by a broken line in FIG. This is a mode in which the voltage of the electrode maintains a low level.

In the first mode, when the rising waveform of the voltage of the scanning electrode (1) and the falling waveform of the voltage of the data electrode both become dull, the scanning electrode (1) shifts from the selected state to the non-selection period. Also, during a certain period, the potential difference between the data electrode and the scanning electrode (1) becomes higher than the threshold value, and
The device emits light. Therefore, the light emission luminance of the organic EL element increases. However, even in this case, when the voltage of the data electrode is maintained at a high level when the voltage of the scan electrode (1) rises after the scan electrode (1) shifts from the selected state to the non-selection period, the organic EL is not changed. The increase in light emission luminance of the device is small. When the all data electrode non-selection period T is not provided, the organic EL element is most used in the mode in which the data electrode maintains the high level among the changes in the voltage of the data electrode when the voltage of the scan electrode (1) rises. Increase in the light emission luminance of the light emitting element. In the present embodiment, there is no mode in which the data electrode maintains the high level when the voltage of the scan electrode (1) rises.

In the second mode, since the voltage of the data electrode is maintained at the low level, after the scan electrode (1) shifts from the selected state to the non-selection period, the voltage between the data electrode and the scan electrode (1) is changed. The potential difference does not exceed the threshold, and the light emission luminance of the organic EL element does not increase.

As described above, in the present embodiment, the data electrode, which is the mode in which the increase in the light emission luminance of the organic EL element is the largest among the changes in the voltage of the data electrode when the voltage of the scan electrode rises, is described. Since there is no way to maintain the high level, uneven brightness can be reduced, and as a result,
The occurrence of shadowing can be prevented.

In this embodiment, since the data electrode voltage rises as the change mode of the data electrode voltage when the scan electrode voltage rises, the data electrode voltage falls steeply. Is better.

Other configurations, operations and effects of the present embodiment are the same as those of the third embodiment.

[Fifth Embodiment] Next, a display device according to a fifth embodiment of the present invention will be described with reference to FIG. The present embodiment is an example in which the all data electrode non-selection period is provided from immediately before the switching of the scanning electrode in the selected state to immediately after the switching. The all data electrode non-selection period is set by setting the data-side enable signal to low level, as in the third embodiment.

FIG. 17 shows an example of a change in the voltage of the scan electrode, the voltage of the data electrode, and the state of the data side enable signal EN in the present embodiment. In this figure, (a) shows a change in voltage of an arbitrary scanning electrode (1), and (b) shows a scanning electrode (2) next to the scanning electrode (1).
(C) shows a change in the voltage of an arbitrary data electrode, and (d) shows a change in the data-side enable signal EN. In the example shown in FIG. 17, the rising waveform of the voltage of the scanning electrode and the rising waveform and falling waveform of the voltage of the data electrode are blunt.

In the example shown in FIG. 17, first, the scanning electrode (1) is in the selected state. At this time, in the example shown by the solid line in FIG. 17 (c), the data electrode is in the selected state.
Next, the scanning electrode (2) is in the selected state. At this time, in the example shown by the solid line in FIG. 17C, the data electrode is in the non-selected state. The data-side enable signal EN is at the low level only during the entire data electrode non-selection period T provided immediately before and after the switching of the scan electrode to be in the selected state, and is at the high level in other periods.
As a result, during the all data electrode non-selection period T, the potential difference between all the scan electrodes and all the data electrodes temporarily becomes smaller than the threshold value.

Hereinafter, in the present embodiment, it will be described that the occurrence of shadowing can be prevented by providing all data electrode non-selection periods T immediately before and after the switching of the scanning electrode to be in the selected state.

In the present embodiment, since all the data electrode non-selection periods T are provided immediately before and after the switching of the scanning electrode to be in the selected state, the voltages of all the data electrodes are set to the selected state. The scanning electrode temporarily goes to a low level immediately before switching, and then maintains the low level until the entire data electrode non-selection period T ends.
Therefore, in the present embodiment, the mode of the voltage change of the data electrode when the voltage of the scan electrode (1) rises after the scan electrode (1) shifts from the selected state to the non-selection period is the voltage of the data electrode. Is only the mode that maintains the low level. In FIG. 17C, a broken line indicates a change in the voltage of the data electrode when the data electrode is in the non-selected state when the scanning electrode (1) is in the selected state, and the scanning electrode (2) is in the selected state. Shows the change in the voltage of the data electrode when the data electrode is in the selected state at the time of
Also in these cases, when the voltage of the scan electrode (1) rises after the scan electrode (1) shifts from the selected state to the non-selection period, the voltage of the data electrode maintains the low level.

As described above, in the present embodiment, the potential difference between the data electrode and the scan electrode (1) becomes equal to or larger than the threshold after the scan electrode (1) shifts from the selected state to the non-selection period. Is prevented. Therefore, according to the present embodiment, it is possible to prevent the occurrence of shadowing.

Further, in the present embodiment, the potential difference between the data electrode and the scan electrode is prevented from exceeding the threshold value after the scan electrode shifts from the selected state to the non-selection period as described above. Therefore, even if the rising waveform of the voltage of the scanning electrode changes depending on the number of unselected data electrodes in an arbitrary scanning electrode, the light emission luminance of the organic EL element is hardly affected by the change.

Other structures, operations, and effects of the present embodiment are the same as those of the third embodiment.

[Sixth Embodiment] Next, a display device according to a sixth embodiment of the present invention will be described with reference to FIG. FIG. 18 is a block diagram illustrating an example of the entire configuration of the display device according to the present embodiment. The display device according to the present embodiment includes, in addition to the components of the display device according to the third embodiment, a scan enable signal generation circuit 40 that generates a scan enable signal, and a data that generates a data enable signal. Side enable signal generation circuit 41
And In the display device according to the present embodiment, main controller 34 does not generate a scan-side enable signal and a data-side enable signal. In the display device according to the present embodiment, the signal lines 57, 61, and 62 are not provided.

The display control unit 35 and each of the enable signal generation circuits 40 and 41 include a signal line 58 for sending a latch pulse from the display control unit 35 to each of the enable signal generation circuits 40 and 41, and A signal line 70 for sending a vertical scanning start signal to the signal generation circuits 40 and 41
And are connected through. Further, the scan side enable signal generation circuit 40 and the scan electrode drive circuit 32 are connected via a signal line 71 for sending a scan side enable signal from the scan side enable signal generation circuit 40 to the scan electrode drive circuit 32. The data-side enable signal generation circuit 41 and the data electrode drive circuits 33A to 33D
3A to 33D are connected via a signal line 72 for sending a data-side enable signal.

In this embodiment, as in the third to fifth embodiments, the non-selection period for all data electrodes is set using the data side enable signal EN. In the present embodiment, the data-side enable signal generation circuit 41 sets the data-side enable signal EN to the low level during the all data electrode non-selection period, with the latch pulse input from the display control unit 35 as a timing reference. I do.

The non-selection period for all data electrodes may be provided immediately before the switching of the scan electrode to be selected, as in the third embodiment, or may be performed in the same manner as in the fourth embodiment. May be provided immediately after the switching of the scanning electrode to be switched, or may be provided immediately before the switching of the scanning electrode in the selected state to immediately after the switching of the scanning electrode, as in the fifth embodiment.

Other configurations, operations and effects of the present embodiment are the same as those of the third to fifth embodiments.

Next, with reference to FIG.
An example of the configuration of the organic EL display used in the display device according to the embodiment will be described. FIG. 19 shows an organic EL
It is explanatory drawing which shows an example of a structure of a display. The organic EL display 31 in this example includes a hole injection electrode 82 between a hole injection electrode (data electrode) 82 and an electron injection electrode (scanning electrode) 87 arranged in a matrix on a substrate 81.
In order from the side, a hole injection layer 83, a hole transport layer 84, a light emitting layer 85, and an electron injection and transport layer 86 are laminated, a protective layer is further laminated as necessary, and a sealing plate such as glass is further formed on these. It has a configuration in which it is arranged. Organic EL elements
It is formed at the intersection of the hole injection electrode 82 and the electron injection electrode 87. In this example, the substrate 81 is a glass substrate,
The data electrode 82 is a transparent electrode.

Next, an example of a method for manufacturing the organic EL display shown in FIG. 19 will be described. In this example, a thin film made of ITO is formed on a glass substrate 81 to a thickness of about 100 nm by a sputtering method. Next, by patterning the obtained thin film made of ITO by etching using photolithography, a hole injection electrode 82 forming a pattern of, for example, 256 × 64 dots (pixels) is formed.

Next, the surface of the substrate on which the above-described hole injection electrode 82 and electrode wiring are formed is washed with ultraviolet and ozone, and then a mask for vapor deposition is mounted on the surface of the substrate. The substrate is fixed, and the pressure inside the apparatus is reduced.

Next, a hole injection layer 83 is formed by evaporating polythiophene to a thickness of 10 nm on the hole injection electrode 82 using a vacuum evaporation apparatus. Next, N, N′-diphenyl-N, N′-m is formed on the hole injection layer 83 while maintaining the reduced pressure state in the vacuum evaporation apparatus.
By depositing tolyl-4,4′-diamino-1,1′-biphenyl (TPD) to a thickness of 35 nm
The hole transport layer 84 is formed.

Next, while maintaining the reduced pressure state in the vacuum deposition apparatus, tris (8-quinolinolato) aluminum (Alq ₃ ) is deposited on the hole transport layer 84 to a thickness of 50 nm, thereby forming the light emitting layer 85. And an electron injection transport layer 86 is formed.

Next, while maintaining the reduced pressure state in the vacuum deposition apparatus, the structure in which the above layers were formed on the substrate 81 was transferred from the vacuum deposition apparatus to the sputtering apparatus, and the electron beam was sputtered at a sputtering pressure of 1.0 Pa. 50 AlLi (Li concentration: 7.2 at%) is placed on the injection / transport layer 86.
The electron injection electrode 87 is formed by forming a film having a thickness of nm. At that time, the sputtering gas was Ar, the input power was 100 W, the size of the target was 4 inches in diameter, and the distance between the substrate and the target was 90 mm.

Next, while maintaining the reduced pressure, the structure formed up to the electron injection electrode 87 is transferred to another sputtering apparatus, and the Al injection is performed on the electron injection electrode 87 by DC sputtering using an Al target. A protective electrode is formed to a thickness of 200 nm. The above-mentioned evaporation mask is removed when the formation of all the layers is completed. Finally, a glass sealing plate is attached to the structure formed up to the Al protective electrode, and the fabrication of the organic EL display 31 is completed.

The display device is manufactured using the organic EL display device 31 manufactured as described above, for example, as follows. That is, for the organic EL display 31,
One scan electrode drive circuit 32 composed of 64 output driver ICs and 4 scan output driver ICs each having 64 output ICs
One of the data electrode driving circuits 33A to 33D is
Implement B (Tape Carrier Package). Furthermore, a printed circuit board (PCB) on which a control circuit such as a controller and a microcomputer is mounted,
The display device is completed by connecting the drive circuits 32 and 33A to 33D with a flat cable.

The present invention is not limited to the above embodiments, but can be variously modified. For example, in the present invention,
The electron injection electrode may be used as a data electrode and the hole injection electrode may be used as a scanning electrode. In this case, when the data electrode is not selected, for example, a power supply voltage is applied to the data electrode.

In the embodiments, the display has a plurality of scanning electrodes and a plurality of data electrodes. However, the present invention is applicable to a case where the number of data electrodes is one or more.

The present invention can be applied not only to a display device having a matrix electrode configuration but also to a display device having a segment electrode configuration.

The present invention is not limited to an organic EL display device, but is applicable to, for example, all display devices having a light emitting element driven by a constant current.

[0224]

As described above, according to the display device of the present invention, the potential of the data electrode is controlled when the selected scan electrode is switched, so that all the scan electrodes are temporarily connected. Since the potential difference between all the data electrodes is set to be less than the threshold value, the charge of the capacitance of the light emitting element connected to each data electrode is changed for all the data electrodes when the selected scan electrode is switched. The accumulation state can be made the same, and with a simple configuration, it is possible to prevent an occurrence of a difference in luminance between pixels according to a light emission pattern. Further, according to the display device of the present invention, when the voltage of the scan electrode rises after the scan electrode shifts from the selected state to the non-selection period, the potential difference between the data electrode and the scan electrode becomes equal to or larger than the threshold value. This is advantageous in that shadowing can be prevented from occurring with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing a configuration of a main part of a display device according to a first embodiment of the present invention.

FIG. 2 is a block diagram illustrating an example of an overall configuration of the display device according to the first embodiment of the present invention.

FIG. 3 is an explanatory diagram showing changes in the states of scan electrodes and data electrodes according to the first embodiment of the present invention.

FIG. 4 is an explanatory diagram illustrating a state of the organic EL element during driving according to the first embodiment of the present invention.

FIG. 5 is an explanatory diagram illustrating a state of the organic EL element at the time of driving according to the first embodiment of the present invention.

FIG. 6 is an explanatory diagram illustrating a state of the organic EL element at the time of driving according to the first embodiment of the present invention.

FIG. 7 is an explanatory diagram showing changes in the states of scan electrodes and data electrodes according to the second embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating a state of an organic EL element at the time of driving according to a second embodiment of the present invention.

FIG. 9 is an explanatory diagram illustrating a state of an organic EL element at the time of driving according to a second embodiment of the present invention.

FIG. 10 is an explanatory diagram illustrating a state of an organic EL element at the time of driving according to a second embodiment of the present invention.

FIG. 11 is an explanatory diagram illustrating an example of a configuration of an organic EL display in the display device according to the first and second embodiments of the present invention.

FIG. 12 is a block diagram illustrating an example of an overall configuration of a display device according to a third embodiment of the present invention.

13 is a block diagram illustrating an example of a configuration of a data electrode drive circuit in FIG.

FIG. 14 is a flowchart illustrating an example of a basic operation of the display device according to the third embodiment of the present invention.

FIG. 15 is an explanatory diagram illustrating an example of a change in the state of a scan electrode voltage, a data electrode voltage, and a data side enable signal according to the third embodiment of the present invention.

FIG. 16 is an explanatory diagram showing an example of a change in the state of a scan electrode voltage, a data electrode voltage, and a data side enable signal according to the fourth embodiment of the present invention.

FIG. 17 is an explanatory diagram showing an example of a change in the state of a scan electrode voltage, a data electrode voltage, and a data side enable signal according to the fifth embodiment of the present invention.

FIG. 18 is a block diagram illustrating an example of an overall configuration of a display device according to a sixth embodiment of the present invention.

FIG. 19 is an explanatory diagram showing an example of the configuration of an organic EL display device in the display device according to the third to sixth embodiments of the present invention.

FIG. 20 is a circuit diagram illustrating an example of a configuration of a display device.

FIG. 21 is a circuit diagram showing an equivalent electric circuit of the organic EL element.

FIG. 22 is an explanatory diagram showing an example of a change in the state of the scanning electrodes and the data electrodes in the display device shown in FIG.

FIG. 23 is an explanatory diagram illustrating a state of an organic EL element during driving in the display device illustrated in FIG. 20;

24 is an explanatory diagram illustrating a state of the organic EL element at the time of driving in the display device illustrated in FIG.

FIG. 25 is an explanatory diagram for describing an example of shadowing.

FIG. 26 is an explanatory diagram showing a relationship between a potential difference between both ends of the organic EL element and a state of electric charge accumulated in the organic EL element.

FIG. 27 is an explanatory diagram showing a transition of a state of charges accumulated in an organic EL element when a scanning electrode changes from a selected state to a non-selected state.

FIG. 28 is an explanatory diagram for explaining that as the number of unselected data electrodes in an arbitrary scanning electrode increases, the rising waveform of the voltage of the scanning electrode becomes dull.

FIG. 29 is an explanatory diagram for explaining that the rising waveform of the voltage of the scan electrode becomes dull as the number of unselected data electrodes in any scan electrode increases.

FIG. 30 is an explanatory diagram showing rising waveforms of voltages of scanning electrodes when there are a small number of unselected data electrodes and when there are many.

FIG. 31 is an explanatory diagram showing an example of a change in the state of a scanning electrode and a data electrode in a conventional display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Organic EL display, 2 ... Scan electrode drive part, 3 ... Data electrode drive part, 4 ... Main control part, 5 ... Display control part, 6 ... Display data storage part, COM1-COMn ... Scan electrode, SEG
1 to SEGm: data electrode, EL _{1,1 to} EL _{m, n} ... organic E
L element, I1 to Im: constant current source, 31: organic EL display, 32: scan electrode drive circuit, 33: data electrode drive section, 33A to 33D: data electrode drive circuit, 34: main control section, 35: display Control unit, 36: display data storage unit.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Yoshihiro Saito 1-13-1 Nihonbashi, Chuo-ku, Tokyo FDT term in TDK Corporation (reference) 3K007 AB02 AB03 BA06 BB07 CA01 CB01 DA00 DB03 EB00 FA01 GA04 5C080 AA06 BB05 DD05 DD09 EE25 FF12 JJ02 JJ03 JJ04 JJ06 5C094 AA07 AA21 AA60 BA02 BA27 CA19 DA09 EA05 EB02 FB01 HA05 HA06 HA08 HA10

Claims (7)

[Claims] A plurality of scan electrodes, at least one data electrode provided to intersect the plurality of scan electrodes, and a plurality of scan electrodes arranged at a portion where the two electrodes intersect and connected to the two electrodes; A display having a plurality of light emitting elements that emit light when the potential difference between them is equal to or greater than a predetermined threshold value; and setting the scan electrodes to different potentials in a selected state and a non-selection state, and sequentially selecting the scan electrodes. Scanning electrode driving means for driving the scanning electrodes to be in a state, and setting the data electrodes in a selected state so that a potential difference between the selected scanning electrodes and the selected data electrodes is equal to or greater than a threshold value. A display device comprising: a data electrode driving unit configured to drive the data electrode so that the data electrode is arbitrarily selected, with different potentials in a non-selected state, and the data electrode driving unit includes: By controlling the potential of the data electrode when the scan electrode selected by the scan electrode driving means is switched, the potential difference between all the scan electrodes and all the data electrodes is temporarily reduced to a threshold value. A display device characterized by being less than. 2. The data electrode driving means temporarily sets a potential difference between all scan electrodes and all data electrodes by setting the potential of the data electrode to a potential in a non-selected state of the data electrode. 2. The display device according to claim 1, wherein the value is less than the threshold value. 3. The data electrode drive means temporarily determines a potential difference between all scan electrodes and all data electrodes after a scan electrode selected by the scan electrode drive means is switched. 3. The display device according to claim 2, wherein all the data electrodes are set in a non-selection state for a predetermined period in order to set the value to less than the value. 4. The data electrode driving means temporarily determines a potential difference between all the scanning electrodes and all the data electrodes before switching the scanning electrode selected by the scanning electrode driving means. 3. The display device according to claim 2, wherein all the data electrodes are set in a non-selection state for a predetermined period in order to set the value to less than the value. 5. The data electrode driving means temporarily switches between all the scanning electrodes and all the data electrodes before and after the switching of the scanning electrode selected by the scanning electrode driving means. 3. The display device according to claim 2, wherein all data electrodes are kept in a non-selected state for a predetermined period in order to make the potential difference of the data electrodes less than the threshold value. 6. The data electrode driving unit according to claim 1, wherein a constant current is supplied to the data electrode in a selected state, and a predetermined potential is applied to the data electrode in a non-selected state. The display device according to any one of the above. 7. The display device according to claim 1, wherein the light emitting element is an organic electroluminescent element.