JP2003271101A - Inorganic el display device, and drive circuit and driving method for the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inorganic EL display device which can display desired gradation without decreasing a dynamic range of brightness, and to provide a drive circuit for the same. <P>SOLUTION: The drive circuits (10, 30) of the inorganic EL display device 1 apply predetermined low voltage V<SB>row</SB>to one selected low electrode line L<SB>row</SB>(m), apply predetermined column voltage V<SB>col</SB>to a plurality of column electrode lines L<SB>col</SB>(n), respectively and apply predetermined data voltage to inorganic EL luminous layers ELR, ELG, and ELB, respectively which are arranged in a pixel P region, and have different light-emitting starting voltage for each luminescent color. The drive circuits (10, 30) have an offset voltage generating circuit 16 which generates offset voltage V<SB>ofst</SB>for adjusting modulation voltage V<SB>m</SB>for each inorganic EL luminous layer ELR, ELG and ELB so that predetermined luminescent brightness is obtained for the same gradation data Data. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to R (red), G
Inorganic EL display device capable of color display by controlling the amount of light emitted from each of the three types of inorganic EL light emitting layers that respectively emit one of the three primary colors (green) and B (blue), and a driving circuit and driving method thereof Regarding

[0002]

2. Description of the Related Art Inorganic EL (electroluminescence)
The display device is characterized by excellent impact resistance and a wide usable temperature range. For this reason, it has been widely used as a display unit for devices such as aircraft, which are used under relatively severe conditions such as medical devices and industrial devices. In recent years, in order to improve its mass productivity, a technique of disposing a thicker high-dielectric layer between the inorganic EL light-emitting layer and the lower electrode line has been developed (for example, Japanese Patent Publication No. 7-44072). (See Japanese Patent Laid-Open No. 7-50197). Furthermore, a thick-film inorganic EL display device for full-color display has been prototyped on the basis of the above technique (for example, DS
eale and X. Wu, Proc. IDW'9
9, 861 (1999)).

FIG. 4 shows a schematic structure of a conventional color thick film inorganic EL display device. Display area 1 as shown in FIG.
Looking toward 08, the thick film inorganic EL display device 100 is
It has a plurality of linear row (row) electrode lines L _row continuously provided in parallel on an insulating substrate. Although not shown in FIG. 4, a relatively thick high-dielectric film is formed on the upper surface of the _row electrode line L _row . The low electrode line L is formed through the high dielectric film and the intermediate layer, phosphor layer, and intermediate layer provided thereon.
Inorganic EL light-emitting layers of a plurality of colors are formed, which extend in a stripe shape in the direction orthogonal to the _rows and are continuously provided in parallel with each other. In FIG. 4, from the left, for example, R
Three types of stripe-shaped inorganic EL light emitting layers R, G, B that emit one color each of the three primary colors of (red), G (green), and B (blue)
Are arranged alternately.

Immediately above the inorganic EL light emitting layers R, G, B, a plurality of linear column electrode lines L _col are arranged in parallel along the inorganic EL light emitting layers R, G, B. Are formed. The intersection of each row electrode line L _row and each column electrode line L _{col serves} as a pixel P, and a plurality of pixels P are arranged in a matrix to form a so-called “passive matrix type”.

Each row electrode line L _row is connected to a row driver 106 having a driving IC mounted thereon. Each of the column electrode lines L _col is grouped into a predetermined number, and the driving IC
Are connected to the column drivers 102 and 104, respectively.

Including the thick-film inorganic EL display device 100
As a driving method for flat panel displays,
There is a line-sequential drive. In line-sequential drive, load line
A plurality of row electrode lines L_rowOne of them is selected
Selected low electrode line L_rowPredetermined low voltage
V_rowIs applied. At the same time, input from an external circuit
Predetermined modulation voltage V based on gradation data_mBut
All column electrode lines L from the column drivers 102 and 104
_colIs applied to each. Selected row electrode line L_row
A low voltage V is applied to the inorganic EL light emitting layer of each pixel P above._row
And each modulation voltage V_mThe data voltage of the difference is
Be added. Selected row electrode line L_rowOf each pixel P above
A large applied voltage (data voltage) is applied from the inorganic EL light emitting layer.
Light having an emission intensity according to the intensity is emitted. This allows
One row electrode line L_rowPlace the pixels P above
It can emit light with constant brightness. For example, multiple rows
Electrode wire L _rowIn order to perform the driving operation in sequence
More, one frame (one screen) image is displayed on the display screen
can do. Compared to dot-sequential drive, line-sequential drive
It is effective for high-speed display because the frame frequency can be increased.
It

FIG. 5 shows the relationship between the voltage applied to the inorganic EL luminescent material layer and the luminescent brightness. The horizontal axis represents time. The upper ordinate represents the applied voltage (V), and the lower ordinate represents the inorganic E.
The light emission brightness (arbitrary unit) of the L light emitter layer is shown. Figure 5
As shown in (4), when the inorganic EL light emitting layer is driven by an applied voltage of the same polarity, the emission intensity gradually decreases, resulting in deterioration of the light emitting characteristics. In order to prevent the deterioration of the light emission characteristic, so-called frame inversion drive is performed in which the polarity of the applied voltage is inverted every frame.

FIG. 6 shows an example of the relationship between the applied voltage to the inorganic EL light emitting layer of each color and the light emission luminance in the color inorganic EL display device using the thick film high dielectric layer. The horizontal axis represents the applied voltage (V) to the inorganic EL light emitting layer, and the vertical axis represents the emission luminance (arbitrary unit). A curve R shown in FIG. 6 shows characteristics of the inorganic EL light emitting layer (R) which emits red light,
A curve G shows the characteristics of the inorganic EL light emitting layer (G) which emits green light, and a curve B shows the characteristics of the inorganic EL light emitting layer (B) which emits blue light. Which curve R, G, B
Also has a gentler gradient than the characteristic of the conventional color inorganic EL display device using the thin film dielectric layer, and it is known that the gradation can be displayed by controlling the luminance by utilizing this characteristic. (See, for example, JP-A-9-179519).
That is, the brightness can be controlled by changing the magnitude of the applied voltage, and more specifically, the brightness can be controlled by changing the potential difference between the low voltage V _row and each modulation voltage V _m .

[0009] In the monochrome thick-film inorganic EL display device of the inorganic EL light-emitting layer only one type, applying a constant low voltage V _row to row electrode lines L _row, and the row voltage V _row to column electrode lines L _col Modulation voltage V _{m at which} the potential difference of V becomes equal to or lower than the light emission start (threshold) voltage V _{th of the} inorganic EL light emitting layer
Is applied to obtain a non-light emitting state, and by applying a modulation voltage V _m whose potential difference from the low voltage V _row exceeds the light emission starting voltage V _th , a light emitting state is obtained.

[0010]

However, as shown by the curves R, G and B in FIG. 6, the inorganic EL light emitting layer (R),
(G) and (B) light emission start (threshold) voltage V
_It is desirable that _th R, V _th G, and V _th B all have the same value, but in reality, as shown in FIG. 6, due to subtle variations in the film forming conditions and heat treatment conditions of the respective phosphors. Often different. In the example shown in FIG. 6, as shown in Table 1 below, V _th R = 160 V, V _th G = 1
50V and _Vth B = 140V. Therefore, as indicated by a broken line parallel to the vertical axis in FIG. 6, even if the same applied voltage (data voltage) is applied to each pixel P, there arises a problem that the emission brightness varies depending on each color. For example, at the position indicated by the broken line in FIG. 6, white display is intended, but red does not emit light at all and green and blue light emission occurs, so that the entire screen becomes a bluish-green image. As described above, when the light emission start voltages V _th R, V _th G, and V _th B do not match, when driving is performed assuming that the light emission start voltage V _th is one type, only a specific color is produced, or a specific color is emitted. Only the brightness is high, and the remaining primary colors have low brightness.

As another flat panel display, for example, in a liquid crystal display device, there is a method of independently correcting the tone of each of R, G and B colors.
It is disclosed in Japanese Patent No. 866. This publication discloses a technique for correcting the R, G, and B color tones by digital calculation using an adjusting circuit. According to this method, the light emission starting voltage can be adjusted, but the color thick film inorganic EL
A self-luminous display device such as a display device is not an effective solution because the dynamic range of the light emission level is limited.

Further, Japanese Unexamined Patent Publication No. 2001-154636 and Japanese Unexamined Patent Publication No. 2001-147666 disclose techniques for improving brightness by using white information. However, since the liquid crystal display device separates the white light from the backlight unit into R, G, and B for display by the color filter, it is not necessary to adjust the brightness at the start of light emission, and the light emission start voltage for each color as described above is not necessary. No consideration is given to different cases.

Japanese Patent Application Laid-Open No. 10-84553 discloses a method for adjusting white balance for a PDP (plasma display panel), which aims to correct the color balance after the start of light emission (so-called γ correction). However, it is not effective at all for the problem peculiar to the color thick film inorganic EL display device that the above-mentioned emission brightness is different for each color.

The light emission start voltage V _{th is set} to the light emission start voltage V _th of each color.
A method in which the lowest voltage value among _th R, V _th G, and V _th B is matched, and for the color of the light emission start voltage higher than that, a difference from the light emission start voltage V _th is given to the gradation data as a weight. Column drivers 102, 104
Since the maximum rating of the driver IC limits the maximum value of the modulation voltage V _m , there is a problem that the dynamic range (variable range) of the brightness becomes narrow.

An object of the present invention is to solve the above problems, and to provide an inorganic EL display device capable of displaying a desired gradation without lowering the dynamic range of luminance, a driving circuit and a driving method thereof. To provide.

[0016]

The above object is to apply a predetermined low voltage to one row electrode line selected from a plurality of row electrode lines, and to apply the plurality of row electrodes via a dielectric film and a light emitting layer. A predetermined modulation voltage is applied to each of a plurality of column electrode lines formed so as to intersect the electrode lines, and
A predetermined data voltage is applied to each inorganic EL light emitting layer which is arranged in each pixel region at the intersection of each row electrode line and each column electrode line and in which a plurality of types of light emitting elements repeat a fixed array pattern. In the method for driving an inorganic EL display device, a modulation voltage to which an offset voltage set for each inorganic EL light emitting layer is added is applied so that a predetermined light emission luminance can be obtained with respect to the same gradation data. This is achieved by a method for driving an inorganic EL display device characterized by the above.

In the method for driving an inorganic EL display device according to the present invention, when performing frame inversion driving in which the polarity of the applied voltage applied to the inorganic EL light emitting layer is reversed in each display frame, positive polarity driving is performed. A predetermined positive polarity offset voltage is applied, and a predetermined reverse polarity offset voltage is applied in reverse polarity.

The above object is to apply a predetermined low voltage to one row electrode line selected from a plurality of row electrode lines,
A predetermined modulation voltage is applied to each of a plurality of column electrode lines formed by intersecting the plurality of row electrode lines with a dielectric film and a light emitting layer interposed between the one row electrode line and each of the column electrodes. A driving circuit of an inorganic EL display device, which is arranged in each pixel region at an intersection with an electrode line and applies a predetermined data voltage to an inorganic EL light emitting layer in which a plurality of types of light emitting elements repeat a fixed array pattern. In addition, an offset voltage generating circuit for generating an offset voltage for adjusting the modulation voltage is provided for each of the inorganic EL light emitting layers so that a predetermined emission brightness can be obtained for the same gradation data. This is achieved by the driving circuit of the inorganic EL display device.

In the drive circuit for an inorganic EL display device according to the present invention, a row driver for applying a predetermined low voltage to the one row electrode line selected from a plurality of row electrode lines,
A column driver that applies a predetermined modulation voltage to each of the plurality of column electrode lines, and the offset voltage generation circuit is provided in the column driver.

In the drive circuit for the inorganic EL display device according to the present invention, the plurality of inorganic EL light emitting layers include an inorganic EL light emitting layer (R) that emits red light and an inorganic E light emitting layer that emits green light.
It has an L luminous body layer (G) and an inorganic EL luminous body layer (B) which emits blue light, and the column driver comprises an inorganic E luminous body layer.
A red column driver for applying a predetermined modulation voltage to the L luminous body layer (R), and an inorganic EL luminous body layer (G)
Is provided with a green column driver for applying a predetermined modulation voltage, and a blue column driver for applying a predetermined modulation voltage to the inorganic EL light emitting layer (B).

In the drive circuit for an inorganic EL display device of the present invention, the offset voltage generation circuit is provided in each of the red column driver, the green column driver, and the blue column driver. Is characterized by.

In the drive circuit for an inorganic EL display device according to the present invention, the gradation data input from the outside is supplied to the red column driver, the green column driver, and the blue column driver for each color. It is further characterized in that it further has a gradation data distribution circuit for distributing the gradation data.

In the above-described drive circuit for an inorganic EL display device of the present invention, the offset voltage generation circuit performs frame inversion drive for reversing the polarity of the applied voltage applied to the inorganic EL light emitting layer for each display frame. For generating a positive polarity offset voltage and a reverse polarity offset voltage.

Further, the above object is to provide a plurality of row electrode lines formed on an insulating substrate and connected in parallel to each other, a dielectric layer formed on the row electrode lines, and an intermediate layer formed thereon. An inorganic EL light emitting layer formed by repeating a fixed array pattern of a plurality of types of light emitting elements, which are periodically arranged in parallel with each other so as to intersect the row electrode lines through a layer, and on the light emitting layer Second inorganic layer provided and the inorganic EL
An inorganic EL display characterized by comprising a plurality of column electrode lines formed along the inorganic EL light-emitting layer substantially directly above the light-emitting layer and connected in parallel with each other, and the drive circuit of the present invention. Achieved by the device.

In the above-mentioned inorganic EL display device of the present invention,
The inorganic EL light emitting layer is formed in a stripe shape for each color.

In the above-mentioned inorganic EL display device of the present invention,
The dielectric film is relatively thick and has a high dielectric constant.

In the above-mentioned inorganic EL display device of the present invention,
The column electrode line is formed on the inorganic EL light emitting layer through a dielectric film.

In the above-mentioned inorganic EL display device of the present invention,
The column electrode wire is formed of a transparent electrode material.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Inorganic according to one embodiment of the present invention
Diagram of EL display device and its driving circuit and driving method
This will be described with reference to FIGS. First, according to the present embodiment
1 is a schematic configuration of a drive circuit of an inorganic EL display device.
This will be described with reference to FIG. FIG. 1 shows the structure according to the present embodiment.
FIG. 3 is a perspective view showing a schematic configuration of a machine EL display device. Figure 2
Is an inorganic EL display device according to the present embodiment and its drive
The schematic structure of a circuit is shown. As shown in FIG.
The color thick film inorganic EL display device 1 according to the embodiment is, for example,
If Al₂O₃On an insulating substrate 2 such as an (alumina) substrate,
A plurality of linear row electrode lines (run
Inspection electrode line) L_row(M) (m is a line number).
Low electrode wire L_row(M) High dielectric material with a relatively thick film on the upper surface
The film 4 is formed. An intermediate layer 6 is formed on the high dielectric film 4.
The low electrode line L is formed in the intermediate layer 6. _rowDirect to (m)
Stretches in the intersecting direction and is parallel to each other
Inorganic EL light-emitting layer EL of a plurality of colors arranged in a cyclic manner is formed.
Is made.

In FIG. 1, from the left, for example, R
Three types of stripe-shaped inorganic EL light-emitting layers (inorganic EL light-emitting layer EL _R for red, inorganic EL light-emitting element for green) that emit light of each of the three primary colors of (red), G (green), and B (blue) Layer EL _G ,
Blue inorganic EL light-emitting layer EL _B) are alternately arranged. As the inorganic EL light emitting layer EL _R for red, for example, Ca
S: Eu is used. Inorganic EL phosphor layer for green EL _G
For example, SrGaS: Eu is used. Also,
As the blue inorganic EL light emitting layer EL _B , for example, BaAl
OS: Eu is used. These materials are sequentially formed on the high dielectric layer 4 by a combination of vapor deposition and photolithography or lift-off.

The above three types of inorganic EL light-emitting layer EL_R, E
L_G, EL_BEach light emission starting voltage V_thR, V_thG, V_thB is
As shown in FIG. 6 and Table 1, the inorganic EL light emitting layer E for red color
L_RLight emission starting voltage V_thR = 160V, not for green
Machine EL luminous body layer EL_GLight emission starting voltage V_thG = 150V
And the inorganic EL light emitting layer EL for blue_BLight emission start voltage
V_thB = 140V. The data shown in Table 1 is for each inorganic
EL luminous body layer EL_R, EL_G, EL_B240 times / sec
Current pulse voltage is applied, the emission brightness is 1 cd / m ²Reach
Voltage to measure the light emission start voltage V_thIt is what
Such a light emission starting voltage V_thR, V_thG, V_thHave B
In the conventional inorganic EL display device, the low electrode line L
_rowLow voltage V in (m)_row= 160V is applied,
Duration voltage V_mInorganic E for blue color without applying
L luminous body layer EL_BAnd green inorganic EL emitter layer EL_GEmits light
Resulting in. For this reason, green or red monochromatic emission is obtained.
I can't. Especially, colors in the low luminance area as a whole
It becomes difficult to adjust the degree.

[0032]

[Table 1]

Returning to FIG. 1, the inorganic EL luminescent material layer E is provided directly on the inorganic EL luminescent material layers EL _R , EL _G and EL _B on the intermediate layer 6.
A plurality of linear column electrode lines (gradation data electrode lines) L _col (n) (n is a column number) that are arranged in parallel along the formation pattern of L _R , EL _G , and EL _B. Are formed. The column electrode line L _col (n) is made of a transparent electrode material such as ITO (indium tin oxide), and light emission is obtained from the surface on the side of the column electrode line L _col (n). . Column electrode line L _col (n)
A cover glass (not shown) is arranged above. As shown in FIG. 2, in the color thick film inorganic EL display device 1, an intersection of each row electrode line L _row (m) and each column electrode line L _col (n) in the display region 32 becomes a pixel P, Pixels P
Are arranged in a matrix so-called "passive matrix type".

As shown in FIG. 2, each row electrode line L
_row (m) is a row driver 30 equipped with a driving IC
It is connected to the. The row driver 30 receives the dot clock DCLK and the horizontal synchronization signal Hsyn that are input from the outside.
c, or one row electrode line L _row (m) is sequentially selected from a plurality of row electrode lines L _row (m) at a predetermined timing based on the vertical synchronization signal Vsync or the like, and the selected _row electrode line L _row (m) is selected. A predetermined low voltage V with respect to L _row (m)
Output _row . Since the frame inversion drive is performed, the positive polarity low voltage V _row (on +) is output in the positive polarity frame, and the reverse polarity low voltage V _row (on is output in the reverse polarity frame.
-) Is output. In the present embodiment, the positive low voltage V
_row (on +) = + 210 V, reverse polarity low voltage V _row (o
n −) = − 160V.

Inorganic EL phosphor layer for red EL_RShaped along
Column electrode line L formed_col(3n-2) (where n =
, 1, 2, 3, ...) are grouped into a predetermined number and
One or more red column drivers with dynamic ICs
10R are connected respectively. Similarly, inorganic for green
EL luminous body layer EL_GColumn electrode line L formed along_c
ol(3n-1) (where n = 1, 2, 3, ...)
1 or 2 which is equipped with driving ICs that are grouped into a predetermined number
Connected to multiple green column drivers 10G respectively
ing. Similarly, an inorganic EL light emitting layer EL for blue color_B
Column electrode line L formed along_col(3n) (However
, N = 1, 2, 3, ...) are summarized for each predetermined number.
One or more blue columns equipped with drive ICs
Each is connected to the driver 10B. Color for red
Driver 10R, green column driver 10G, blue
Column driver by combining the column driver 10B for
Ibar 10 is configured. In addition, in FIG. 2, an inorganic EL display
Column drivers 10R, 10G, 10 for the left end of the panel
Only part of B is shown.

The column driver 10 and the row driver 30 form a drive circuit for the inorganic EL display device of this embodiment. The row electrode line L _row selected by this drive circuit
(M) is arranged in each pixel P region at the intersection of each column electrode line L _col (n), and the emission start voltage V _th R for each emission color,
Inorganic EL light emitting layers EL _R and E having different V _th G and V _th B
A predetermined data voltage is applied to each of L _G and EL _B.

In line-sequential driving, the inorganic EL display device 1 is connected to
From the system side, such as continued computers, once per 1
The gradation data for the row electrode lines (one scanning line) is the column electrode lines.
L_{co l}Output in the order of numbers (n) (ascending or descending)
It Note that R, G, and
The gradation data of the three primary colors of B are analog data and digital data.
Input to the column driver 10
The digital number of bits corresponding to the number of display gradations.
Input as data. In this embodiment, the system side
Explanation that digital gradation data is input from
To do. The gradation data Data has, for example, 8 bits each.
Red gradation data Data (R) and green gradation
Data Data (G) and blue gradation data Data
(B), it is possible to display 256 gradations for each color.
Has become.

The column drivers 10R and 10 shown in FIG.
G and 10B have the same circuit configuration. For example, the column driver 10R has a shift register 20R to which digital gradation data Data is input. The shift register 20R has, for example, 30 stages, and one column driver 10R can output grayscale data to 30 column electrode lines L _col (n). The shift register 20R synchronizes with the dot clock DCLK sent from the control unit (not shown) and the red gradation data Data.
(R) is sequentially taken into each stage.

The output terminals of the stages 1 to 30 of the shift register 20R are connected to the latch circuit 22R of the next stage.
Red gradation data Dat on all stages of the shift register 20R
When a latch pulse is output after a (R) is stored,
The latch circuit 22R latches the red gradation data Data (R) of each stage of the shift register 20R.

A reference voltage selection circuit 24R is provided next to the latch circuit 22R. Reference voltage selection circuit 24R
_Has a voltage selection unit (not shown) for each column electrode line L _col (n), and selects any of 256 levels of voltage value supplied from the reference voltage supply circuit 18R to select each column electrode line L _col (n). It is adapted to be applied to L _col (n).

The reference voltage supply circuit 18R has a ladder resistance section (not shown) for supplying a modulation voltage. 255 resistors R1 to R255 are connected in series to the ladder resistor portion, and a voltage V is applied to one terminal on the resistor R1 side.
_max = 50 V is applied, the voltage V _min = 0V = V _GND to the other terminal of the resistor R255 side is applied, the voltage width of the modulation voltage V _m is adjusted to 50 V. From the ladder resistance part, the modulation voltage line is drawn from each connection point of the adjacent resistance by tap connection,
By dividing the resistance, voltage values in 256 levels from V _{max to} V _min are supplied to the reference voltage selection circuit 24R through 256 modulation voltage lines.

Each column driver 10R, 10G, 10B
In order to obtain a predetermined (or the same) emission luminance for the same gradation data, the inorganic EL light emitting layer EL _R ,
Modulation voltage V _m R, V _m G, for each EL _G , EL _B ,
Offset voltage generation circuits 16R, 16G, and 16B that apply an offset voltage V _ofst that adjusts V _m B are provided.

Offset voltage generation circuit 16R for each color, 1
6G and 16B are connected to a positive power source + V _CC and a reverse polarity power source -V _EE , respectively.
_A desired positive offset voltage V _ofst + and reverse polarity offset voltage V _ofst − are _obtained by resistance division by a ladder resistance circuit in which a plurality of resistors having a predetermined resistance value are connected in series between _CC and the reverse polarity power supply −V _EE. Each can be output.

The red offset voltage generating circuit 16R is
Red inorganic EL luminescent layer EL_RModulation for red
Voltage V_mRed positive offset voltage for adjusting R
Pressure V_{o fst}Reverse polarity offset voltage V for R + and red_ofstR-
And are output to the red reference voltage supply circuit 18R.
ing. In the present embodiment, as shown in Table 2, red
Offset voltage (V_ofstR +) and reverse polarity for red
Offset voltage (V_{of st}Both R-) are 0V.

The offset voltage generation circuit 16G for green is green
It is installed in the color column driver 10G and emits green inorganic EL.
Optical layer EL_GModulation voltage V for green_mAdjust G
For positive polarity offset voltage V for green_ofstG + and green
Reverse polarity offset voltage for color V _ofstG- and the reference voltage for green
The pressure is supplied to the pressure supply circuit 18G. Implementation
In the embodiment, as shown in Table 2, the positive polarity offset for green color is used.
Voltage (V_ofstG +) = + 10, the reverse polarity for green
Husset voltage (V_ofstG-) =-10V.

The blue offset voltage generation circuit 16B is blue
It is provided in the color column driver 10B and emits blue inorganic EL.
Optical layer EL_BBlue modulation voltage V_mAdjust B
Positive polarity offset voltage V for blue_ofstB + and blue
Reverse polarity offset voltage for color V _ofstB and-for blue reference voltage
The pressure is supplied to the pressure supply circuit 18B. Implementation
In the embodiment, as shown in Table 2, positive polarity offset for blue color is used.
Voltage (V_ofstB +) = + 20, the reverse polarity for blue
Husset voltage (V_ofstB-) =-20V.

The red reference voltage supply circuit 18R is provided with a changeover switch (not shown) for switching the offset voltage based on a predetermined polarity signal. With the change-over switch, the offset voltage applied to the ladder resistance portion can be switched to either the red positive polarity offset voltage V _ofst R + or the red reverse polarity offset voltage V _ofst R−.

Green and blue reference voltage supply circuits 18G,
18B also has a changeover switch (not shown) that switches the offset voltage based on a predetermined polarity signal. With this changeover switch, the blue reference voltage supply circuit 18G,
Positive offset voltage V _ofst G is applied to the ladder resistor of 18B.
+, V _ofst B + or reverse polarity offset voltage V _ofst G-,
V _ofst B- can be switched and applied.

To summarize the above, in the red reference voltage selection circuit 24R, the red reference voltage supply circuit 18R
During positive polarity driving, the positive polarity offset voltage for red (V _ofst
R +) = 0 V offset is applied to the voltage V _max = +
A modulation voltage V _m R divided into 256 is obtained within the range of 50 V to voltage V _min = 0V. When driving in reverse polarity, the reverse polarity offset voltage for red (V _ofst R-)
= 0V offset is applied to the voltage V _max = + 50V
A modulation voltage V _m R divided into 256 is obtained within the range of voltage V _min = 0V. The red reference voltage selection circuit 24R selects one from a total of 256 red modulation voltages V _m R based on the grayscale data Data latched by the latch circuit 24R and the polarity signal.

Similarly, the green reference voltage selection circuit 24
In G, the green reference voltage supply circuit 18G causes the green positive offset voltage (V _ofst G +) during positive driving.
= + 10 V offset is applied to the voltage V _max = + 6
The modulation voltage V _m G divided into 256 is obtained within the range of 0 V to the voltage V _min = + 10 V. Further, during reverse polarity driving, the reverse polarity offset voltage for green (V _ofst G
−) = − 10 V offset applied to voltage V _max =
A modulation voltage V _m G divided into 256 is obtained within the range of +40 V to voltage V _min = −10 V. The green reference voltage selection circuit 24G selects one from a total of 256 green modulation voltages V _m G based on the grayscale data Data latched by the latch circuit 24G and the polarity signal.

Similarly, in the blue reference voltage selection circuit 24B, the blue reference voltage supply circuit 18B causes
During positive polarity driving, the positive polarity offset voltage for blue (V _ofst
B +) = + 20V offset is multiplied by the voltage V _max
The modulation voltage V _m B divided into 256 is obtained within the range of +70 V to voltage V _min = + 20 V. When driving in reverse polarity, the reverse polarity offset voltage for blue (V
_ofst B −) = − 20V offset is applied to the voltage V
_max = + _30V~ 256 within the voltage V _min = -20 V
A divided modulation voltage V _m B is obtained. The blue reference voltage selection circuit 24B, based on the grayscale data Data and the polarity signal latched by the latch circuit 24B,
One is selected from a total of 256 blue modulation voltages V _m B.

[0052]

[Table 2]

As shown in FIG. 2, in the inorganic EL display device 1 according to this embodiment, in order to perform frame inversion drive,
Grayscale data polarity inversion capable of outputting the reverse polarity grayscale data Data (-) in which each bit of the 8-bit grayscale data Data input from the system side is inverted to have a reverse polarity based on a predetermined polarity signal. It has a circuit 12. The gradation data polarity reversing circuit 12 outputs the gradation data Data as it is in the case of a normal frame, and outputs the reverse polarity gradation data Data (-) in the case of a reverse frame.

The output terminal of the gradation data polarity inversion circuit 12 is connected to the input terminal of the gradation data distribution circuit 14. The gradation data distribution circuit 14 distributes and outputs the input gradation data Data to each of the red column driver 10R, the green column driver 10G, and the blue column driver 10B for each color. ing.

Next, a display method and a driving method of the inorganic EL display device 1 according to this embodiment will be described with reference to FIGS. 1 and 2 and FIG. FIG. 3 is a timing chart illustrating a driving method of the inorganic EL display device 1 according to this embodiment.

First, the operation in the positive polarity frame f _n in FIG. 3 will be described. Gradation data polarity reversal circuit 12
Determines based on the polarity signal whether the gradation data Data for one row electrode line (one scanning line) sequentially input from the system side is for the positive polarity frame or for the reverse polarity frame. . If it is determined that the grayscale data Data is for the positive polarity frame, the grayscale data Data is output to the grayscale data distribution circuit 14 as it is.

In the gradation data distribution circuit 14, the input gradation data Data is supplied to the red column driver 10R for each color.
And output to one of the green column driver 10G and the blue column driver 10B.

The shift register 20R of the red column driver 10R sequentially takes in the grayscale data Data (R) to each stage in synchronization with the dot clock DCLK sent from the control unit (not shown). When the grayscale data Data (R) is stored in all the stages of the shift register 20R and a latch pulse is output from a control unit (not shown), the latch circuit 22R simultaneously latches the grayscale data of each stage of the shift register 20R. To do.

At this time, the red reference voltage supply circuit 18 has already been
R is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistor section is switched to the red positive offset voltage V _ofst R +.

Therefore, the red reference voltage selection circuit 24
Each voltage selection unit (not shown) of R has a voltage V _max offset by a positive polarity offset voltage for red (V _ofst R +) = 0V based on each gradation data Data (R) latched by the latch circuit 22R. = + 50V to voltage V _min = 0V
Modulation voltage V _m divided into 256 within the range of
Select one of R and select each column electrode line L _col (3n-2)
Apply all at once.

Similarly, the shift register 20G of the green column driver 10G sequentially takes in the grayscale data Data (G) to each stage in synchronization with the dot clock DCLK. Gradation data Data (G) is provided in all stages of the shift register 20G.
Is stored and a latch pulse is output from a control unit (not shown), the latch circuit 22G simultaneously latches the grayscale data (G) of each stage of the shift register 20G.

At this time, the green reference voltage supply circuit 18 has already been
G is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistor section is switched to the positive polarity offset voltage for green V _ofst G +.

Therefore, the green reference voltage selection circuit 24
Each voltage selection unit (not shown) of G is connected to the latch circuit 22G.
Based on each gradation data Data (G)
Positive offset voltage (V_ofstG +) = + 10V off
Set voltage V_{ma x}= + 60V to voltage V_min=
Modulation divided into 256 within + 10V
Voltage V_mSelect one of G and select each column electrode line L_col(3n
-1) is applied all at once.

Similarly, the shift register 20B of the blue column driver 10B also sequentially takes in the gradation data Data (B) to each stage in synchronization with the dot clock DCLK. Gradation data Data (B) is provided in all stages of the shift register 20B.
Is stored and a latch pulse is output from a control unit (not shown), the latch circuit 22B simultaneously latches the grayscale data of each stage of the shift register 20B.

At this time, the blue reference voltage supply circuit 18 has already been
B is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistor section is switched to the blue positive offset voltage V _ofst B +.

Therefore, the blue reference voltage selection circuit 24
Each voltage selection unit (not shown) of B is connected to the latch circuit 22B.
For blue based on each gradation data Data (B)
Positive offset voltage (V_ofstB +) = + 10V off
Set voltage V_{ma x}= + 70V to voltage V_min=
Modulation divided into 256 within the range of + 20V
Voltage V_mSelect one of B and select each column electrode line L_col(3
Apply all at once to n).

In synchronization with the above operation, the row driver 30
Is a dot clock DCLK, a horizontal sync signal Hsync, or a vertical sync signal Vsync that is input from the outside.
Based on the equal, selects a predetermined one row electrode line L _row (m), the positive polarity low with respect to the selected row electrode line L _row (m) based on the polarity signal voltage V _row (on + ) =
Outputs + 210V.

As a result, the selected row electrode line L _row
(M) Red inorganic EL light-emitting layer EL of red pixel P on the above
_R has a positive low voltage V _row (on +) = + 210 V and a positive red modulation voltage V _m R = + 50 V.
A data voltage having a potential difference of 0V is applied. That is,
Inorganic EL for red on the selected row electrode line L _row (m)
The light emitting layer EL _R has a red light emission start voltage V _th R = 160.
A data voltage of V to 210 V is applied to emit light having an emission intensity according to the magnitude of the data voltage.

Similarly, the selected row electrode line L
_The positive polarity low voltage V _row (on +) = + 210 is applied to the green inorganic EL light emitting layer EL _G of the green pixel P on the _row (m).
V and modulation voltage V _m G = + 60 for positive polarity green
A data voltage having a potential difference of V to + 10V is applied. That is, the green inorganic EL light-emitting layer EL _G on the selected row electrode line L _row (m) has a green light emission start voltage V _th G.
A data voltage of 150 V to 200 V is applied, and light having an emission intensity corresponding to the magnitude of the data voltage is emitted.

Similarly, the selected row electrode line L _{row is selected.}
(M) Inorganic EL light emitting layer EL for blue of the blue pixel P on (m)
_B has a positive low voltage V _row (on +) = + 210 V and a positive blue modulation voltage V _m B = + 70 V.
A data voltage having a potential difference of + 20V is applied. That is, the blue inorganic EL light emitting layer EL _B on the selected row electrode line L _row (m) has a blue light emission start voltage V _th B = 1.
A data voltage of 40V to 190V is applied to emit light having an emission intensity according to the magnitude of the data voltage. As a result, all the pixels P on the selected row electrode line L _row (m) can be made to emit light with predetermined brightness.

By doing so, the light emission starting voltages V _th R and V _{th of the} inorganic EL light emitting layers EL _R , EL _G and EL _B for the respective colors are obtained.
Even if G and V _th B do not match, a predetermined (or the same) emission luminance can be obtained for the same gradation data.
Therefore, even if the same gradation data is given, it is possible to prevent a problem that only a specific color is produced or only the brightness of the specific color is high and the remaining primary colors have low brightness.

In the driving method according to the present embodiment, since the gradation data itself is not weighted, the maximum value of the modulation voltage V _m is not limited, and the voltage range of 50 V is applied to any color. Since the modulation voltage V _m can be obtained, a dynamic range of brightness can be secured. However, weighting the gradation data for the purpose of improving the color balance of each color is
It is an effective method and does not undermine the object of the present invention.

Next, the operation in the reverse polarity frame f _{n + 1} will be described with reference to FIG. Gradation data polarity inversion circuit 1
2 is the reverse polarity gradation data Data when it is judged that the gradation data Data for one row electrode line (one scanning line) sequentially input from the system side is for the reverse polarity frame.
(-) Is output to the gradation data distribution circuit 14.

In the gradation data distribution circuit 14, the inputted reverse polarity gradation data Data (-) is selected for each color from the red column driver 10R, the green column driver 10G, and the blue column driver 10B. The output destination is distributed to and output.

The shift register 20R of the red column driver 10R synchronizes with the dot clock DCLK sent from a control unit (not shown) and reverse polarity gradation data Data.
(R-) is sequentially taken into each stage. Shift register 20R
When the reverse polarity grayscale data Data (R−) is stored in all the stages and the latch pulse is output from the control unit (not shown),
The latch circuit 22R simultaneously latches the reverse polarity gradation data (R-) of each stage of the shift register 20R.

At this time, the red reference voltage supply circuit 18 has already been
R is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistor section is switched to the red reverse polarity offset voltage V _ofst R−.

Therefore, the red reference voltage selection circuit 24
Each voltage selection unit (not shown) of R has a reverse polarity offset voltage for red (V _ofst R −) = 0V based on the reverse polarity gradation data Data (R−) latched by the latch circuit 22R.
Of each of the column electrode lines L by selecting one of the modulation voltages V _m R divided by 256 within the range of the voltage V _max = + 50 V to the voltage V _min = 0 V to which the offset is applied.
_It is applied to _col (3n-2) all at once.

Similarly, the shift register 20G of the green column driver 10G sequentially takes in the reverse polarity grayscale data Data (G-) to each stage in synchronization with the dot clock DCLK. When the reverse polarity grayscale data Data (G-) is stored in all the stages of the shift register 20G and a latch pulse is output from the control unit (not shown), the latch circuit 22G causes the grayscale data of each stage of the shift register 20G. Latch all at once.

At this time, the green reference voltage supply circuit 18 has already been
G is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistor section is switched to the reverse polarity offset voltage V _ofst G- for green.

Therefore, the green reference voltage selection circuit 24
Each voltage selection unit (not shown) of G has a reverse polarity offset voltage for green (V _ofst G −) = − 1 based on the reverse polarity gradation data Data (G−) latched by the latch circuit 22G.
0V offset voltage V _max = + 40V ~
One of the modulation voltages V _m G divided into 256 within the range of voltage V _min = −10 V is selected and applied to each column electrode line L _col (3n−1) all at once.

Similarly, the shift register 20B of the blue column driver 10B also sequentially takes in the reverse polarity gradation data Data (B-) to each stage in synchronization with the dot clock DCLK. When the reverse polarity grayscale data Data (B−) is stored in all the stages of the shift register 20B and a latch pulse is output from a control unit (not shown), the latch circuit 22B causes the grayscale data of each stage of the shift register 20B. Latch all at once.

At this time, the blue reference voltage supply circuit 18 has already been
B is a changeover switch based on a predetermined polarity signal,
The offset voltage applied to the ladder resistance section is switched to the blue reverse polarity offset voltage V _ofst B−.

Therefore, the blue reference voltage selecting circuit 24
Each voltage selection unit (not shown) of B, based on each reverse polarity gradation data Data (B-) latched by the latch circuit 22B, has a blue reverse polarity offset voltage (V _ofst B-) = _-2.
0V offset voltage V _max = + 30V ~
One of the modulation voltages V _m B divided into 256 within the range of voltage V _min = −20 V is selected and applied to each column electrode line L _col (3n) all at once.

The row driver 30 is synchronized with the above operation.
Is a dot clock DCLK, a horizontal sync signal Hsync, or a vertical sync signal Vsync that is input from the outside.
Based on the equal, selects a predetermined one row electrode line L _row (m), opposite polarity on the row electrode line L _row (m) which is the selected on the basis of the polarity signal LOW voltage V _row (on -) =
Outputs -160V.

As a result, the selected row electrode line L _row
(M) Red inorganic EL light-emitting layer EL of red pixel P on the above
_{For R} , a reverse polarity low voltage V _row (on −) = − 160 V and a reverse polarity red modulation voltage V _m R = + 50 V
A data voltage having a potential difference of 0V is applied. That is,
Inorganic EL for red on the selected row electrode line L _row (m)
The light emitting layer EL _R has a red light emission start voltage V _th R = 160.
A data voltage of V to 210 V is applied to emit light having an emission intensity according to the magnitude of the data voltage.

Similarly, the selected row electrode line L
_The reverse polarity low voltage V _row (on −) = − 160 is applied to the green inorganic EL light emitting layer EL _G of the green pixel P on the _row (m).
V and reverse polarity green modulation voltage V _m G = + 40
A data voltage having a potential difference of V to -10V is applied. That is, the green inorganic EL light-emitting layer EL _G on the selected row electrode line L _row (m) has a green light emission start voltage V _th G.
A data voltage of 150 V to 200 V is applied, and light having an emission intensity corresponding to the magnitude of the data voltage is emitted.

Similarly, the selected row electrode line L _{row is selected.}
(M) Inorganic EL light emitting layer EL for blue of the blue pixel P on (m)
_B has a reverse polarity low voltage V _row (on −) = − 160 V and a reverse polarity blue modulation voltage V _m B = + 30 V
A data voltage having a potential difference of −20V is applied. That is, the blue inorganic EL light emitting layer EL _B on the selected row electrode line L _row (m) has a blue light emission start voltage V _th B = 1.
A data voltage of 40V to 190V is applied to emit light having an emission intensity according to the magnitude of the data voltage. As a result, all the pixels P on the selected row electrode line L _row (m) can be made to emit light with predetermined brightness.

By doing so, the reverse polarity frame f
_{Also in n + 1} , the inorganic EL light emitting layers EL _R and E for each color
Even if the light emission start voltages V _th R, V _th G, and V _th B of L _G and EL _B do not match, a predetermined (or the same) light emission luminance can be obtained for the same gradation data. Therefore, even if the same gradation data is given, only a specific color is produced,
Alternatively, it is possible to prevent a problem that only the brightness of a specific color is high and the remaining primary colors have low brightness.

Also in the reverse polarity frame f _{n + 1} , since the grayscale data itself is not weighted, the maximum value of the modulation voltage V _m is not limited and the voltage range of 50 V is applied to any color. Since the modulation voltage V _m can be obtained, a dynamic range of luminance can be secured. However, weighting the gradation data for the purpose of improving the color balance of each color is
It is an effective method and does not undermine the object of the present invention.

[0090]

As described above, according to the present invention, each inorganic E
Since the offset voltage corresponding to the difference in the light emission start voltage of the L luminous body layer is applied to the column electrode line driving IC corresponding to the specific color to correct the difference in the light emission start voltage, Optimal display can be realized by correcting the emission brightness based on the emission characteristics.

[Brief description of drawings]

FIG. 1 is a perspective view showing a schematic configuration of an inorganic EL display device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a schematic configuration of an inorganic EL display device and its drive circuit according to an embodiment of the present invention.

FIG. 3 is a diagram showing a timing chart illustrating a driving method of an inorganic EL display device according to an embodiment of the present invention.

FIG. 4 is a diagram showing a schematic configuration of a conventional inorganic EL display device.

FIG. 5 is a diagram showing light emission characteristics of an inorganic EL display device during pulse driving.

FIG. 6 is a diagram showing voltage-light emission luminance of a conventional inorganic EL display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Inorganic EL display device 2 Insulating substrate 4 Dielectric layer 6 Intermediate layer 10 Column driver 10R Red column driver 10G Green column driver 10B Blue column driver 12 Gradation data polarity reversing circuit 14 Gradation data distribution circuit 16R Red Offset voltage generating circuit 16G for green offset voltage generating circuit 16B for blue offset voltage generating circuit 18R, 18G, 18B reference voltage supply circuit 30 low driver 32 display area EL _R inorganic EL light emitting layer EL for red EL _G inorganic EL light emitting for green Body layer EL _B Inorganic EL light emitting layer for blue f _n Frame L _row (m) Row electrode line L _col (n) Column electrode line + V _CC Positive power supply −V _EE Reverse polarity power supply V _GND Ground voltage V _m Modulation voltage V _m R for red modulation voltage V _m G for green modulation voltage V _m B for blue modulation ® emission voltage V _ofst R + red positive offset voltage V _ofst R- red opposite polarity offset voltage V _ofst G + green positive offset voltage V _ofst G-green opposite polarity offset voltage V _ofst B + blue positive offset voltage V _ofst B− For blue Reverse polarity offset voltage V _row Low voltage V _row (on +) Positive polarity low voltage V _row (on−) Selected reverse polarity low voltage V _th Light emission start (threshold) voltage V _th R For red Light emission start voltage V _th G Green light emission start voltage V _th B Blue light emission start voltage

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) G09G 3/20 G09G 3/20 642J H05B 33/12 H05B 33/12 B (72) Inventor Ishibashi Mitsuru Tokyo 1-13-1, Nihonbashi, Chuo-ku T-DK Corporation F-term (reference) 3K007 AB04 BA06 DA05 GA04 5C080 AA06 BB05 CC03 DD05 EE28 FF12 JJ02 JJ04 JJ05 JJ06

Claims (12)

[Claims] 1. A predetermined low voltage is applied to one row electrode line selected from a plurality of row electrode lines, and the plurality of row electrode lines are formed so as to intersect with the plurality of row electrode lines via a dielectric film and a light emitting layer. A predetermined modulation voltage is applied to each of the plurality of column electrode lines, and each of the plurality of column electrode lines is arranged in each pixel region at the intersection of the one row electrode line and each of the column electrode lines. A method of driving an inorganic EL display device, wherein a predetermined data voltage is applied to an inorganic EL light emitting layer formed by repeating an array pattern, wherein a predetermined light emission brightness is obtained for the same gradation data. A method for driving an inorganic EL display device, which comprises applying a modulation voltage to which an offset voltage set for each inorganic EL light-emitting layer is added. 2. The method for driving an inorganic EL display device according to claim 1, wherein when performing frame inversion driving in which the polarity of the applied voltage applied to the inorganic EL light emitting layer is reversed in each display frame, a positive electrode is used. A method of driving an inorganic EL display device, characterized in that a predetermined positive polarity offset voltage is applied in a positive polarity drive, and a predetermined reverse polarity offset voltage is applied in a reverse polarity. 3. A row electrode line selected from a plurality of row electrode lines is applied with a predetermined low voltage so as to intersect the plurality of row electrode lines via a dielectric film and a light emitting layer. A predetermined modulation voltage is applied to each of the plurality of column electrode lines, and each of the plurality of column electrode lines is arranged in each pixel region at the intersection of the one row electrode line and each of the column electrode lines. A driving circuit of an inorganic EL display device, wherein a predetermined data voltage is applied to an inorganic EL light-emitting layer formed by repeating an array pattern, wherein a predetermined emission brightness is obtained for the same gradation data. A driving circuit for an inorganic EL display device, comprising an offset voltage generating circuit for generating an offset voltage for adjusting the modulation voltage for each inorganic EL light emitting layer. 4. The drive circuit for an inorganic EL display device according to claim 3, wherein a row driver applies a predetermined low voltage to the one row electrode line selected from a plurality of row electrode lines, and the plurality of columns. A driving circuit for an inorganic EL display device, comprising: a column driver that applies a predetermined modulation voltage to each electrode line; and the offset voltage generating circuit is provided in the column driver. 5. The drive circuit for an inorganic EL display device according to claim 4, wherein the plurality of inorganic EL luminescent material layers are inorganic E that emits red light.
The column driver includes an L light emitting layer (R), an inorganic EL light emitting layer (G) that emits green light, and an inorganic EL light emitting layer (B) that emits blue light. A red column driver for applying a predetermined modulation voltage to the body layer (R), a green column driver for applying a predetermined modulation voltage to the inorganic EL light emitting layer (G), and an inorganic EL light emitting layer (B). A driving circuit for an inorganic EL display device, comprising: a blue column driver for applying a predetermined modulation voltage. 6. The drive circuit for an inorganic EL display device according to claim 5, wherein the offset voltage generation circuit is provided in each of the red column driver, the green column driver, and the blue column driver. A drive circuit for an inorganic EL display device characterized in that. 7. The drive circuit for an inorganic EL display device according to claim 5, wherein the gradation data input from the outside is supplied to each of the red column driver and the green column driver for each color. The drive circuit for an inorganic EL display device, further comprising: a gradation data distribution circuit that distributes to the blue column driver. 8. The drive circuit for an inorganic EL display device according to claim 3, wherein the offset voltage generation circuit applies an applied voltage to the inorganic EL light emitting layer for each display frame. A drive circuit for an inorganic EL display device, which generates a positive polarity offset voltage and a reverse polarity offset voltage for performing frame inversion driving in which the polarities are reversed. 9. A plurality of row electrode lines formed on an insulating substrate and arranged in parallel with each other, a dielectric film formed on the row electrode lines, and the row electrode via the dielectric film. An inorganic EL light emitting layer, in which a plurality of types of light emitting elements repeat a certain arrangement pattern in parallel to each other and intersects a line, is disposed by being sandwiched by upper and lower intermediate layers, and is substantially directly above the inorganic EL light emitting layer. 9. A plurality of column electrode lines, which are formed along the inorganic EL light-emitting layer and are continuously arranged in parallel with each other, and the drive circuit according to claim 3. Inorganic EL display device. 10. The inorganic EL display device according to claim 9, wherein the dielectric film is a relatively thick film and has a high dielectric constant. 11. The inorganic EL display device according to claim 9, wherein the column electrode line is formed on the inorganic EL light emitting layer through a dielectric film. Display device. 12. The inorganic EL display device according to claim 9, wherein the column electrode lines are made of a transparent electrode material.