JP4082886B2 - Organic electroluminescence display device and mobile phone - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an organic electroluminescence display device and a mobile phone including the same.
[0002]
[Prior art]
In recent years, organic electroluminescence displays (hereinafter referred to as organic EL displays) have been developed, and for example, adopting organic EL displays in mobile phones has been studied.
As shown in FIGS. 3 and 4, the organic EL display has an organic hole transport layer (15) and an organic electron transport layer (16) on both sides of the organic light emitting layer (14) based on the glass substrate (11). The organic layer (13) is formed, and the anode (12) and the cathode (17) are disposed on both sides of the organic layer (13), and the organic layer (13) is disposed between the anode (12) and the cathode (17). A predetermined voltage is applied to the organic light emitting layer (14) to emit light.
[0003]
The anode (12) is made of transparent indium tin oxide (ITO), and the cathode (17) is made of, for example, an Al—Li alloy, and is formed in stripes and arranged in a matrix in a direction crossing each other.
The anode (12) is used as a data electrode, and the cathode (17) is used as a scanning electrode. With one scanning electrode extending in the horizontal direction selected, each data electrode extending in the vertical direction is adapted to the input data. By applying the applied voltage, the organic layer (13) is caused to emit light at the intersection of the scanning electrode and each data electrode, thereby displaying one line. Then, scanning is performed in the vertical direction by sequentially switching the scanning electrodes in the vertical direction, and display for one frame is performed.
[0004]
As a driving method for such an organic EL display (1), as described above, a passive matrix driving method in which time division driving is performed using scanning electrodes and data electrodes, and light emission of each pixel is maintained over one vertical scanning period. An active matrix driving method is known.
[0005]
In the active matrix drive type organic EL display, as shown in FIG. 5, for each organic EL element (18) that should constitute one pixel (10), a write transistor TR1 that exhibits an on / off function; A driving transistor TR2 that converts input data into a current value and a capacitive element C that exhibits a memory function are provided.
The gate driver (61) that drives the scan electrodes and the source driver (62) that drives the data electrodes constitute a drive circuit (6).
[0006]
First, a voltage is sequentially applied to each scanning electrode by the gate driver (61) to turn on the writing transistor TR1 connected to the same scanning line, and data is supplied to the source driver (62) in synchronization with this scanning. At this time, since the write transistor TR1 is in a conductive state, the data is stored in the capacitor C.
Next, the operating state of the drive transistor TR2 is determined by the amount of charge of data stored in the capacitive element C. For example, assuming that the driving transistor TR2 is in an operating state, a current is supplied to the organic EL element (18) via the driving transistor TR2. As a result, the organic EL element (18) is turned on. This lighting state is maintained for one vertical scanning period.
[0007]
The organic EL display (1) is a self-luminous display as described above, and only the necessary pixels need to be lit. Therefore, the organic EL display (1) consumes less power than a liquid crystal display in which the backlight needs to be lit constantly. Savings are possible.
[0008]
[Problems to be solved by the invention]
However, since the power consumption of mobile phones has increased with the recent increase in functionality and color display, when an organic EL display is adopted for a mobile phone, the power consumption of the organic EL display can be further reduced. It is desirable to do.
SUMMARY OF THE INVENTION An object of the present invention is to provide an organic EL display device capable of reducing power consumption as compared with the prior art and a mobile phone including the organic EL display device.
[0009]
[Means for solving the problems]
Therefore, in the present invention, when displaying characters, the background portion is often displayed as white, and the character portion is displayed as black. In this case, in order to display a background portion having a larger area than the character portion in white, a large amount is displayed. Focusing on the fact that power is consumed, the power consumption is reduced as a whole by reducing the power required for character display.
[0010]
That is, the organic EL display device according to the present invention is
Text discriminating means for discriminating whether or not the input data is text data;
When the input data is text data, the input data is corrected so that the background portion is displayed in black and the character portion is displayed in a color having a higher luminance than the background portion. First data correction means for supplying to the drive circuit ;
Means for determining the data amount of the input data, which is determined according to the gradation of the image to be displayed by the input data when the input data is not text data;
For input data whose data amount is determined to be smaller than a predetermined threshold value, second data correction means for correcting for lowering the luminance of input data to be displayed at least in the intermediate luminance band /> And.
[0011]
According to the organic EL display device of the present invention, when the input data is text data, the background portion having a large area is displayed in black, so that power consumption is reduced compared to the case where the background portion is displayed in white. Is done. In addition, since the character portion is displayed in a color with higher brightness than the background portion, there is no problem in the visibility of the character shape.
If the input data is, for example, graphic data or image data and is not text data, by determining the data amount of the input data, data such as graphic data having a data amount less than a predetermined threshold is determined, and the data Is corrected by further reducing the luminance of the intermediate luminance band, and the data is displayed. As a result, overall power consumption can be reduced. However, intermediate brightness band data will be displayed with low brightness, but high brightness band and low brightness band data will be displayed as they are, especially for data with a small amount of data such as animation graphic data. For this reason, degradation of image quality is not a big problem.
[0012]
In a specific configuration, the data correction means adds correction for inverting the display color between white and black for input data to be displayed in white for the background portion and black for the character portion.
As a result, the background portion is reversed from white to black and the character portion is reversed from black to white, so that power consumption is reduced and the visibility of the character shape is maintained.
[0014]
A mobile phone according to the present invention is a mobile phone comprising the above organic electroluminescence display device.
Comprising means for measuring the duration of the state where the key operation is not being performed, when the measured time exceeds a predetermined threshold value, the input data, make modifications to gradually reduce the brightness of the display It is characterized by.
[0015]
According to the mobile phone of the present invention, when no key operation is performed for a certain time, it is determined that there is no need to display data on the organic EL display device, and the luminance is gradually reduced. As a result, the display on the organic EL display device gradually fades and eventually disappears completely. Thereby, the power consumption of the organic EL display device can be reduced.
Thereafter, if any key operation is performed, the display by the organic EL display device is resumed.
In the case of an organic EL display device, the light emission is stopped at the same time as the light emission is stopped. However, in the present invention, since the luminance is gradually reduced, the problem caused by the instantaneous light disappearance is a problem. Does not occur.
[0016]
【The invention's effect】
According to the organic EL display device and the mobile phone according to the present invention, it is possible to reduce power consumption as compared with the related art.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention in a mobile phone will be described in detail with reference to the drawings.
The mobile phone according to the present invention includes an organic EL display (1) as shown in FIGS. 3 to 5, and a drive circuit (6) shown in FIG. 1 is connected to the organic EL display (1). The gate drive signal and the source drive signal are supplied from the drive circuit (6) to the organic EL display (1).
[0018]
For example, when data is downloaded using the communication function of a cellular phone, the data is first supplied to the text discrimination circuit (2), and it is discriminated whether or not the data is text data. When it is determined that the data is text data, the data is supplied to the black-and-white inversion circuit (3). As shown in FIG. 2 (a), the data to be displayed in white in the background portion and black in the character portion is shown in FIG. ), The background portion is converted into data to be displayed in black and the character portion in white, and is supplied to the drive circuit (6).
As a result, on the organic EL display (1), as shown in FIG. 2B, the background portion is displayed in black and the character portion is displayed in white.
[0019]
On the other hand, when it is determined by the text determination circuit (2) shown in FIG. 1 that the data is not text data, the data is supplied to the data amount determination circuit (4), and the data amount exceeds a predetermined threshold value. It is determined whether or not. Here, if the amount of data does not exceed the predetermined threshold, the data is considered to be data with coarse gradation such as, for example, animation graphic data. Therefore, the data is supplied to the gamma characteristic changing circuit (5). Then, by changing the gamma characteristic, processing for lowering the luminance by a predetermined value is added to the data in the intermediate luminance band, and then the data is supplied to the driving circuit (6).
[0020]
On the other hand, when the amount of data exceeds a predetermined threshold, the data is considered to be image data with fine gradation such as image data obtained by taking a photograph, for example, and processing for partially reducing the luminance is added. Since this is inappropriate, the gamma characteristic changing circuit (5) is passed through without processing and supplied to the driving circuit (6).
[0021]
As a result, when the input data is text data or data other than text data and a relatively small amount of data, the display brightness of the organic EL display (1) is suppressed as a whole, and the organic EL display ( The power consumption of 1) will be saved.
[0022]
In addition, each part structure of this invention is not restricted to the said embodiment, A various deformation | transformation is possible within the technical scope as described in a claim. For example, when the background portion and the character portion are respectively displayed in color, the background portion may be displayed in black, and the character portion may be displayed in the same color or in another color that can be distinguished from black.
Also, the data obtained from the black and white inversion circuit (3) or the gamma characteristic changing circuit (5) is placed between the black and white inversion circuit (3) and gamma characteristic changing circuit (5) and the drive circuit (6) shown in FIG. When a key operation has not been performed for a predetermined time or more with a circuit to which processing for gradually decreasing the luminance is added to the whole, the circuit is operated to gradually increase the luminance of the display. The power consumption of the organic EL display (1) can be reduced also by the configuration in which the power consumption is reduced.
[Brief description of the drawings]
FIG. 1 is a block diagram showing a configuration of a main part of a mobile phone according to the present invention.
FIG. 2 is an explanatory diagram of processing for reversing black and white of a character display.
FIG. 3 is a diagram showing a laminated structure of an organic EL display.
FIG. 4 is a partially broken perspective view of an organic EL display.
FIG. 5 is a diagram illustrating a configuration of an active matrix driving type organic EL display;
[Explanation of symbols]
(1) Organic EL display
(12) Anode
(13) Organic layer
(17) Cathode
(2) Text discrimination circuit
(3) Black and white inversion circuit
(4) Data amount judgment circuit
(5) Gamma characteristic change circuit
(6) Drive circuit
(61) Gate driver
(62) Source driver

Claims (4)

In an organic electroluminescence display device that emits an organic layer by arranging a pair of positive and negative electrodes on both sides of the organic layer and applying a voltage according to input data between both electrodes by a drive circuit,
Text discriminating means for discriminating whether or not the input data is text data;
When the input data is text data, the input data is corrected so that the background portion is displayed in black and the character portion is displayed in a color having a higher luminance than the background portion. First data correction means for supplying to the drive circuit ;
Means for determining the data amount of the input data, which is determined according to the gradation of the image to be displayed by the input data when the input data is not text data;
For input data determined to have a data amount smaller than a predetermined threshold value, second data correction means for performing correction for lowering brightness for input data to be displayed in at least an intermediate brightness band < An organic electroluminescence display device comprising: 2. The organic data according to claim 1, wherein the first data correction unit adds correction for inverting the display color between white and black for input data to be displayed with a white background and a black character portion. Electroluminescence display device. In an organic electroluminescence display device that emits an organic layer by arranging a pair of positive and negative electrodes on both sides of the organic layer and applying a voltage according to input data between both electrodes by a drive circuit,
Text discriminating means for discriminating whether or not the input data is text data;
Means for determining the data amount of the input data, which is determined according to the gradation of the image to be displayed by the input data when the input data is not text data;
Wherein the input data whose data amount is determined to less than a predetermined threshold value, the target input data to be displayed at least the middle of the luminance band, data correction means for applying a correction for reducing the luminance
An organic electroluminescence display device characterized by comprising: A mobile phone comprising the organic electroluminescence display device according to any one of claims 1 to 3,
Comprising means for measuring the duration of the state where the key operation is not being performed, when the measured time exceeds a predetermined threshold value, the input data, make modifications to gradually reduce the brightness of the display A mobile phone characterized by.

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