JP2002091379A - Method for driving capacitive light emitting element display and control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure linearity of brightness to a visual sense in a digital capacitive light emitting element display. SOLUTION: An emitted light quantity in each gradation is made variable by arbitrarily dividing a light emitting time, and further arbitrarily controlling the time. Concretely, the light emitting brightness in each gradation is controlled by arbitrarily dividing the light emitting time of the element according to a value to be set programmable to a gradation control register 5, and further, arbitrarily controlling the time. A gradation variable trigger generation circuit 4 starts a gradation pulse output circuit 3 and generates a gradation pulse having a pulse width in accordance with the value set in the gradation control register 5, and supplies it to an element drive circuit 2. The element drive circuit 2 drives a display panel main body 1, to obtain a desired gradation display.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention
The present invention relates to a method for driving a capacitive light emitting device display and a control device thereof, which are suitable for gradation control of (electroluminescence).

[0002]

2. Description of the Related Art In a flat panel light emitting display such as an organic EL, a light emitting diode, or a plasma, the amount of light emitted from each dot can be changed by changing the amount of charge injected during a driving period of a target element. . Therefore, the current value is changed or the current value is fixed and the ON
There are two ways to change the time.

The former is usually called an analog type, and the latter is called a digital or time division type. The analog type requires high-precision linearity in order to change the drive current in accordance with the luminance value, and has a drawback that the drive unit becomes large and the drive current value changes depending on temperature or the like. On the other hand, the latter digital type only needs to output a constant current, so that the driving unit is downsized and the temperature characteristics are good.
Accordingly, digital displays are often used in capacitive EL displays such as organic EL devices.

[0004]

In the above-mentioned organic EL element display employing the digital method, the organic EL element display is used.
FIGS. 10 to 12 show anode drive waveforms when driving the L element.

FIGS. 10 to 12 show current drive waveforms for each gradation level (gradation 1, gradation 2, and gradation 3) as timing charts. Conventionally, as shown in FIG. The required light emission time of the element is equally divided (e gradation image), the light emission luminance is varied by changing the light emission amount, and gradation control is performed. The description of the timing charts shown in FIGS. 10 to 12 will be described later in comparison with the timing charts shown in FIGS. 4 to 6 of the present invention.

As described above, in a conventional organic light emitting device such as an organic EL, when the necessary light emission time of an element is equally divided and gradation expression is performed, the light emission time of each gradation is determined by the necessary light emission time. As a result, the amount of light emission within each gradation cannot be changed. Therefore, the light emission luminance is determined by the light emission characteristics of the element, and it has not been possible to perform gradation control that is excellent in ergonomics or that has high flexibility and expandability in consideration of the effect on vision.

The present invention has been made in view of the above circumstances, and arbitrarily divides the light emission time, and arbitrarily controls the divided time so that the current ON time for the element can be changed for each gradation. Accordingly, it is an object of the present invention to provide a method for driving a capacitive light emitting device display and a control device therefor, which ensure linearity of luminance with respect to visual perception.

[0008]

In order to solve the above-mentioned problems, the invention according to the first aspect of the present invention is to fix the current or voltage value and change the light emission amount of each dot by controlling the light emission time. A method of driving a capacitive light emitting device display that performs tone control, wherein the light emission time is arbitrarily divided, and the light emission amount in each gradation is made variable by arbitrarily controlling the divided time. It is characterized by the following.

The invention described in claim 2 is the first invention.
In the method for driving a capacitive light emitting device display according to the above item, the color mixture is optimized by arbitrarily setting the division time for each color.

According to a third aspect of the present invention, there is provided a capacitor for controlling gradation by changing a light emission amount of each dot by controlling a light emission time by fixing a current or voltage value. A drive control device for a luminescent element display, wherein a gradation pulse output circuit that generates and outputs a gradation pulse to an element drive circuit for the staircase display, and a pulse width value of the gradation pulse is programmable. And the width of a reference clock input for gradation control from the outside is made variable based on the value set in the gradation register. And a gradation variable trigger generating circuit for supplying a trigger for pulse generation.

[0011] The invention described in claim 4 is the same as the claim 3.
In the drive control device for a capacitive light emitting device display according to the above, the pulse width set in the gradation control register is supplied with an optimized value defined in advance for each color by an externally connected microcomputer. It is characterized by.

With the above-described structure, the light emission luminance of each element can be controlled by arbitrarily dividing the light emission time of the element in accordance with the value set in the gradation control register and arbitrarily controlling the time. it can. As a result, the characteristics of the light emitting element can be made variable by controlling the luminance without changing the color, efficiency, and the like, and the optimal mixed color development can be made when the influence on human vision is considered. It is possible to provide a light emission driving method of a capacitive light emitting device display device and a control device thereof.

[0013]

FIG. 1 is a block diagram showing one embodiment of a drive control device for a capacitive light emitting device display according to the present invention.

In FIG. 1, a drive control device for a capacitive light emitting device display according to the present invention comprises an EL display panel main body 1, an element drive circuit 2, and a gradation pulse output circuit 3.
, A grayscale variable trigger generation circuit 4 and a grayscale control register 5.

In the EL display panel body 1, an EL element (not shown) is connected to each intersection of an anode line and a cathode line arranged in a matrix, one of which serves as a scanning line and the other serves as a driving line. The drive circuit 2 connects a current source to a desired drive line in synchronization with the scan line while scanning the scan line at a predetermined cycle, thereby causing a desired EL element to emit light. This is a simple matrix drive type capacitive light-emitting display panel that performs a reset operation for releasing accumulated charges of elements.

The gradation pulse output circuit 3 supplies a gradation trigger clock cka (b) generated and output by the gradation variable trigger generation circuit 4 to the element drive circuit 3. The gradation variable trigger generation circuit 4 receives a reference clock c from outside.
kd (a) and a grayscale start signal (s) and a grayscale end signal (e) which are control signals are input, and a grayscale trigger clock generated based on a value set in a grayscale control register 5 described later. ckd (b) is supplied to the gradation pulse output circuit 3. A value is set in the gradation control register 5 in a programmable manner by a microcomputer (not shown).

FIG. 2 shows the bit assignment of the gradation control register 5. The gradation control register 5 has 8 bits (DB7 to DB7).
A gradation setting register 51 of DB0) and a gradation start setting register 52 of 8 bits in the same manner. The least significant bit (DB0) of the gradation setting register 51 sets whether or not gradation control is possible. The setting register 52 sets the gradation level and the number of clocks for each gradation level. In the gradation start setting register 52, the start clock position (G2) of the gradation level 2 in the upper 4 bits (DB7 to DB4) and the start clock position (G3) of the gradation level 3 in the lower 4 bits (DB3 to DB0). ) Is set, whereby the reference clock ck is set for each gradation level.
The tone trigger clock c generated from d (a)
The output pulse width of ka (b) is set. FIG. 3 shows a value setting example in the gradation control register 5 and a clock waveform at that time. Here, the gradation setting register 5
The operation waveform when the least significant bit of 1 is turned ON, G2 of the gradation start setting register 52 is set to "3", and G3 of the gradation start setting register 52 is set to "7" is shown.

FIGS. 4 to 6 are views cited for explaining the operation of the embodiment of the present invention. In each of FIGS. 4 to 6, the gradation levels 1, 2, and 3 are set. The current drive waveform is shown.

FIGS. 4 to 6 show (a)
Reference clock cdd, (b) gradation variable trigger cka,
(C) a scanning line drive signal LS (Line Sync), (d) a cathode reset signal, (e) a gradation image, (f) a gradation pulse width, (g) a dimmer pulse width, and (h) a device drive waveform. .

As described above, the present invention performs gradation control by fixing the current or voltage value and controlling the light emission time to change the light emission amount of each dot in the EL display panel main body 1. The light emission time is arbitrarily divided, and the light emission amount in each gradation is made variable by arbitrarily controlling the divided time. this is,
As shown in (e) gradation images of FIGS.
The light emission time at each gradation is different depending on the gradation variable trigger cka (b), and the gradation pulse width (f) and the current drive waveform (h) at that time are shown in FIGS. 4, 5 and 6, respectively. Are different. This is based on the value set in the gradation control register 5.

In this way, the emission time of the EL element is arbitrarily divided, and the emission time of each gradation is controlled by arbitrarily controlling the time. Without changing the characteristics (color, efficiency, etc.) of the light emitting element, the luminance of the light emitting element can be controlled in the same manner as when the γ value (the ratio of the change in the voltage conversion value to the change in the luminance) is corrected, and the luminance for human vision The linearity of is secured.

FIG. 7 is a diagram showing an image of luminance with respect to gradation, with the horizontal axis representing the gradation level and the vertical axis representing the number of pulses. Here, six patterns are shown in which the one-gradation start position is fixed at “0”, the two-gradation start position, the three-gradation start position, and the pulse width at each are variable. As can be seen from the figure, a natural display is obtained in the setting of the pattern 6. In consideration of the characteristics of the light emitting element and the effect on the visual sense, it is preferable that the pattern can be arbitrarily changed in this way, and the pattern can be selected by the value set in the gradation control register 5. Optimization of mixed color development is performed by arbitrarily setting the division time for each gradation.

The table below the graph shows the pulse ratio and the total gradation ratio for each pattern.
FIGS. 8 and 9 show measured luminance data in the green dot portion and the blue dot at the time of setting each pulse, respectively. In each case, the horizontal axis represents the gradation level,
The vertical axis indicates measured luminance data (cd).

As described above, according to the present invention, the light emission time is arbitrarily divided and the divided time is arbitrarily controlled to control the current ON time for the element for each gradation. Thus, the linearity of the luminance with respect to the visual sense is ensured. In the above-described embodiment of the present invention, the time interval for dividing the light emission time of the element is determined according to the value set in the register. ,
The amount per unit time during voltage driving may be controlled, and the same effect can be obtained by performing γ correction on the luminance of the light emitting element.

[0025]

As described above, according to the present invention, the light emission time of the element is arbitrarily divided according to the value set in the gradation control register in a programmable manner, and the time is arbitrarily controlled to control each floor. It is possible to control the light emission luminance in the tone. As a result, by controlling the luminance without changing the characteristics of the light emitting element, such as color and efficiency, γ
The luminance of the light emitting element can be controlled in the same manner as when the value (the ratio of the change in the voltage conversion value to the change in luminance) is corrected, and the linearity of the luminance with respect to human vision is ensured. Therefore, it is possible to provide a method of driving light emission of a capacitive light emitting device display device and a control device therefor, which enable optimal mixed color development in consideration of the influence on human vision.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an embodiment of a light emission drive control device for a capacitive light emitting device display device according to the present invention.

FIG. 2 is a diagram showing bit assignment of a gradation control register in FIG. 1;

3 is a diagram showing a relationship between a value set in a gradation control register in FIG. 1 and an output waveform of a gradation variable trigger generation circuit.

FIG. 4 is a timing chart cited for explaining the operation of the embodiment of the present invention.

FIG. 5 is a timing chart cited for explaining the operation of the embodiment of the present invention.

FIG. 6 is a timing chart cited for explaining the operation of the embodiment of the present invention.

FIG. 7 is a graph and a table cited for explaining an image of luminance for each gradation.

FIG. 8 is a graph and a table showing measured data of a green dot portion when each pulse is set.

FIG. 9 is a graph and a table showing measured data of a blue dot portion when each pulse is set.

FIG. 10 is a timing chart showing a gradation control operation of a conventional light emission drive control device of a capacitive light emitting element display device.

FIG. 11 is a timing chart showing a gradation control operation of a conventional light emission drive control device of a capacitive light emitting device display device.

FIG. 12 is a timing chart showing a gradation control operation of a light emission drive control device of a conventional capacitive light emitting element display device.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... EL display panel main body, 2 ... Element drive circuit, 3 ...
Gradation pulser output circuit, 4 ... gradation variable trigger generation circuit,
5: gradation control register, 51: gradation setting register, 52
… Grayscale start setting register

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 3K007 AB03 AB04 AB17 BA06 DA01 DB03 EB00 GA04 5C080 AA06 BB05 CC03 DD03 DD30 EE29 FF12 JJ02 JJ04 JJ05

Claims (4)

[Claims] 1. A method for driving a capacitive light emitting element display in which a current or voltage value is fixed and a light emission time is controlled to change a light emission amount of each dot to perform gradation control, wherein the light emission time is arbitrarily set. A method for driving a capacitive light-emitting element display, wherein the amount of light emission in each gradation is made variable by arbitrarily controlling the divided time. 2. The method for driving light emission of a capacitive light emitting device display according to claim 1, wherein the mixed color development is optimized by arbitrarily setting the division time for each color. 3. A drive control device for a capacitive light emitting element display, wherein a gradation value is controlled by changing a light emission amount of each dot by controlling a light emission time by fixing a current or voltage value, A grayscale pulse output circuit for generating and outputting a grayscale pulse to an element driving circuit for display; a grayscale control register for setting a pulse width value of the grayscale pulse in a programmable manner; Variable trigger generation circuit for making the width of the reference clock input for the variable based on the value set in the gray scale register and supplying the width as a trigger for gray scale pulse generation to the gray scale pulse output circuit A light emission drive control device for a capacitive light emitting device display device, comprising: 4. The pulse width set in the gradation control register is supplied with an optimized value defined in advance for each color by an externally connected microcomputer. Drive control device for capacitive light emitting device display.