Method of power conservation for organic light-emitting display according to light emitting area ratio

Provided is an organic light-emitting display device. The organic light-emitting display device includes a light-emitting unit having a plurality of OLEDs to emit light, a light-emitting level setting unit setting a light-emitting level depending on a light-emitting area and/or change in a light-emitting degree of the light-emitting unit, a look-up table in which data for the light-emitting degree of the light-emitting unit that corresponds to each light-emitting area for each light-emitting level is set and stored, a light-emitting control unit controlling the light-emitting area of the light-emitting unit and/or the light-emitting degree depending on a light-emitting level with reference to the data set on the look-up table.

CROSS-REFERENCE TO RELATED APPLICATION

This application is the U.S. national stage application of International Patent Application No. PCT/KR2006/002334, filed Jun. 19, 2006, which claims priority to Korean Patent Application No. KR10-2005-0052447, filed Jun. 17, 2005, the disclosure of each of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to an organic light-emitting display device and a driving method thereof.

BACKGROUND ART

Generally, an organic light-emitting display device is a self-luminous display device electrically exciting a phosphorous organic compound to emit light and supplying a current to an N×M matrix consisting of organic light-emitting diodes (OLEDs) to drive the N×M matrix of OLEDs and thus display an image.

A method for driving the OLEDs includes a passive matrix method and an active matrix method using transistors. In the passive matrix method, an anode and a cathode are perpendicularly formed, and a line is selected to drive an organic light-emitting display device. On the other hand, in the active matrix method, transistors and condensers are provided, and a voltage supplied through the transistors is maintained to drive an organic light-emitting display device.

However, when the organic light-emitting display device is used for a mobile communication terminal or a large-scale image display device, there is a serious problem that the organic light-emitting display device consumes much power. Therefore, a research for reducing power consumption of an organic light-emitting display device is in progress in various ways.

DISCLOSURE OF INVENTION

Technical Problem

The present invention is to provide an organic light-emitting display device and a driving method thereof, capable of managing power consumption below a set value regardless of a light emitting area and a light emitting degree of a light-emitting unit having organic light-emitting devices.

The present invention is to provide a mobile communication terminal including an organic light-emitting display device, capable of managing power consumption below a set value regardless of a light emitting area and a light emitting degree of a light-emitting unit having organic light-emitting devices.

Technical Solution

The present invention provides an organic light-emitting display device including: a light-emitting unit having a plurality of OLEDs to emit light; a light-emitting level setting unit setting a light-emitting level depending on a light-emitting area and/or a change in a light-emitting degree of the light-emitting unit; a look-up table in which data for the light-emitting degree of the light-emitting unit that corresponds to each light-emitting area for each light-emitting level is set and stored; a light-emitting control unit controlling the light-emitting area and/or the light-emitting degree of the light-emitting unit depending on a light-emitting level with reference to the data set on the look-up table.

The present invention provides a method of driving an organic light-emitting display device, the method including: extracting data from an input frame and setting a light-emitting level according to a light-emitting area and a change in a light-emitting degree of a light-emitting unit having a plurality of OLEDs; and controlling the light-emitting area and/or light-emitting degree of the light-emitting unit according to the set light-emitting level and displaying an image.

The present invention provides a method of driving an organic light-emitting display device, the method including: extracting data from an input frame and setting a light-emitting level according to a light-emitting area and a change in a light-emitting degree of a light-emitting unit having a plurality of OLEDs; and controlling the light-emitting area and/or light-emitting degree of the light-emitting unit according to the set light-emitting level, and controlling an input current value input to the light-emitting unit to display an image.

The present invention provides a mobile communication terminal including: an organic light-emitting display device including a light-emitting unit having a plurality of OLEDs to emit light, a light-emitting level setting unit setting a light-emitting level according to a light-emitting area of the light-emitting unit and/or a change in a light-emitting degree, a look-up table in which data for the light-emitting degree of the light-emitting unit that corresponds to each light-emitting area for each light-emitting level is set and stored according to the light-emitting level set by the light-emitting level setting unit, a light-emitting control unit controlling the light-emitting area of the light-emitting unit and/or the light-emitting degree depending on a light-emitting level with reference to the data set on the look-up table; a communication element performing communication with the outside; and a controller controlling the communication element and image display by the organic light-emitting display device.

Advantageous Effects

According to the present invention, it is possible to manage power consumption below a set value regardless of a light emitting area and a light emitting degree of a light-emitting unit having an organic light-emitting device.

MODE FOR THE INVENTION

FIG. 1is a schematic block diagram of an organic light-emitting display device according to the present invention.

Referring toFIG. 1, the light-emitting display device includes a light-emitting unit11, a light-emitting level setting unit13, a look-up table (LUT)15, and a light-emitting control unit17.

Here, the light-emitting unit11includes a plurality of OLEDs to emit light over an entire area or a partial area under control of the light-emitting control unit17. At this point, the light-emitting control unit17controls a light-emitting area and/or light-emitting degree of the light-emitting unit11according to a relevant light-emitting level with reference to data set on the look-up table15.

Also, the light-emitting level setting unit13sets a light-emitting level depending on a light-emitting area of the light-emitting unit and/or a change in a light-emitting degree of the light-emitting unit11. That is, the light-emitting level setting unit13extracts data from an input image frame to set a light-emitting level of the input frame. Data for a light-emitting degree of the light-emitting unit11that corresponds to each light-emitting area for each light-emitting level according to the light-emitting level set in this manner may be obtained from the look-up table15.

After that, the light-emitting control unit17controls the light-emitting area and/or light-emitting degree of the light-emitting unit11with reference to the set data stored in the look-up table15when displaying an image contained in a next frame.

Here, the light-emitting control unit17drives the OLEDs of the light-emitting unit11using a value less than data of a light-emitting degree stored in the look-up table15according to a relevant light-emitting level.

The light-emitting level setting unit13may extract data from an entire image display region of an input frame to set a light-emitting level. Also, the light-emitting level setting unit13extracts data from a partial image display region of an input frame to set a light-emitting level. At this point, the light-emitting level setting unit13may classify and set the light-emitting level using power consumption of the light-emitting unit11when setting the light-emitting level.

On the other hand, data for the light-emitting degree stored in the look-up table15may contain information regarding a maximum light-emitting time and/or maximum number of light-emitting depending on the light-emitting area of the light-emitting unit11. Here, the data for the light-emitting degree stored in the look-up table15is set such that a maximum light-emitting time and/or maximum number of light-emitting of the light-emitting unit11decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level.

Also, the light-emitting control unit17controls an input current value input to the light-emitting unit11together with the light-emitting area and/or light-emitting degree of the light-emitting unit11depending on the light-emitting level when controlling the light-emitting unit11to drive the OLEDs.

Also, an example of a method of driving an organic light-emitting display device according to the present invention will be described with reference toFIG. 2, which is a flowchart illustrating a method of driving an organic light-emitting display device according to the present invention.

On the first place, according to the method, data is extracted from an input frame and then a light-emitting level is set according to a light-emitting area and a change in a light-emitting degree of the light-emitting unit having a plurality of OLEDs (operation201).

Here, assuming that light-emitting levels are classified into 256 levels, for example, when the light-emitting levels are set, a level for a largest light-emitting area with consideration of a light-emitting degree may be expressed as255, and a level for a smallest light-emitting area may be expressed as 0. The setting of the light-emitting level for each level will be described below.

At this point, the light-emitting area means an actual light-emitting area of the light-emitting unit having the plurality of OLEDs. Referring toFIG. 3, the light-emitting area11a,11b, and11cmay change into various sizes.FIG. 3is a diagram explaining a change in a light-emitting area of an organic light-emitting display device according to the present invention.

Also, according to a method of driving an organic light-emitting display device, a light-emitting area and/or light-emitting degree of the light-emitting unit is controlled according to the set light-emitting level, so that an image is displayed (operation203).

Data for the light-emitting degree proposed by the present invention may contain information regarding a maximum light-emitting time and/or maximum number of light-emitting depending on the light-emitting area of the light-emitting unit11.

Here, referring toFIG. 4, the data for the light-emitting degree is set such that a maximum light-emitting time of the light-emitting unit11decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level.FIG. 4is a view explaining a light-emitting time of each organic light-emitting device during one frame for a light-emitting area of an organic light-emitting display device in a method of driving an organic light-emitting display device according to the present invention.

Referring toFIG. 5, the data for the light-emitting degree is set such that the number of light-emitting of the light-emitting unit11decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level.FIG. 5is a view explaining the number of light-emitting of each organic light-emitting device during one frame for a light-emitting area of an organic light-emitting display device in a method of driving an organic light-emitting display device according to the present invention.

The data for a light-emitting degree that corresponds to each light-emitting area for each light-emitting level is stored in the look-up table, and the look-up table is referred, so that a driving condition of the OLEDs of the light-emitting unit may be easily obtained.

FIG. 6is a view illustrating an example where a light-emitting area and a light-emitting degree within the area of an organic light-emitting display device are defined in a method of driving an organic light-emitting display device according to the present invention.

Referring toFIG. 6, the light-emitting level may be defined as 128 levels using “White window pattern” Here, “100% white window pattern” corresponds to a level where all pixels contained in a screen are turned on with maximum brightness (a largest data input). Also, “20% white window pattern” corresponds to a level where a same pattern is displayed with an area portion of 20% in an entire screen. The “20% white window pattern” has been set to a level 0. At this point, a “white window pattern having an area less than 20% corresponds to a level 0, of course, and a pattern showing the same power consumption as that of the white window pattern having a relevant area in an aspect of power consumption regardless of an image pattern is also regarded as being the same light-emitting level. Power consumption of the light-emitting unit may be obtained through analysis of input data.

On the other hand, according to a related art method of driving an organic light-emitting display device, power consumption is generated as illustrated inFIG. 7.FIG. 7is a view illustrating power consumption versus a light-emitting area ratio when an input current value of an organic light-emitting device is constant in a method of driving an organic light-emitting display device according to the present invention.

That is, assuming that patterns (here, “white window pattern”) in which an image is displayed is the same and only a difference in a light-emitting area is present in the related art method of driving the organic light-emitting display device, power consumption increases in direct proportion to a light-emitting area as the light-emitting area increases as illustrated inFIG. 7because a current value input to each OLED constituting the light-emitting unit has a constant maximum value and the number of pixels emitting light is in direct proportion to an area.

However, according to a method of driving an organic light-emitting display device of the present invention, power consumption illustrated inFIG. 8is generated.FIG. 8is a view illustrating power consumption when an input current value of an organic light-emitting device is controlled according to a light-emitting area in a method of driving an organic light-emitting display device according to the present invention.

According to the present invention, since a light-emitting area having a level less than a predetermined level (here, 20%) is defined as a level 0, power consumption for a pattern where an area with consideration of a light-emitting degree (intensity) is less than 20% increase in direct proportion to the light-emitting area as in the related art.

However, it is possible to drive such that an organic light-emitting display device has power consumption less than a predetermined value regardless of a light-emitting area on which an image is displayed as illustrated inFIG. 8by controlling a light-emitting time or the number of light-emitting of each OLED for a pattern where the light-emitting area is more than 20%. Such constant power consumption can be realized by reducing the light-emitting time and/or the number of light-emitting of each OLED as the light-emitting area increases.

FIG. 9is a flowchart illustrating a method of driving an organic light-emitting display device according to another embodiment of the present invention.

According to the method, data is extracted from an input frame, and a light-emitting level is set according to a light-emitting area and a change in a light-emitting degree of a light-emitting unit having a plurality of OLEDs (operation901).

Also, according to the method, the light-emitting area and/or light-emitting degree of a light-emitting unit according to the set light-emitting level, and simultaneously, an input current value input to the light-emitting unit is controlled, so that an image is displayed (operation903).

Data for the light-emitting degree proposed by the present invention may contain information regarding a maximum light-emitting time and/or maximum number of light-emitting depending on the light-emitting area of the light-emitting unit11.

Here, referring toFIG. 4, the data for the light-emitting degree is set such that a maximum light-emitting time of the light-emitting unit11decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level. Referring toFIG. 5, the data for the light-emitting degree is set such that the number of light-emitting of the light-emitting unit11decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level.

Also, the input current value input to the light-emitting unit is set such that a maximum current value input to the light-emitting unit decreases as the light-emitting area of the light-emitting unit11increases for the same light-emitting level.

The data for the light-emitting degree that corresponds to each light-emitting area for each light-emitting level, and data for the input current are stored in the look-up table, and the look-up table is referred, so that a driving condition of the OLEDs of the light-emitting unit may be easily obtained.

At this point, the OLEDs of the light-emitting unit are driven using values less than the data for the light-emitting degree (light-emitting time and the number of light-emitting) and the data for the input current stored in the look-up table when the light-emitting unit is controlled according to the set light-emitting level and an image is displayed. It is possible to set an operation condition below predetermined power consumption using the above-described driving method.

On the other hand, referring toFIGS. 10 and 11, the present invention can analyze a pattern for determining a light-emitting level with consideration of a light-emitting area and a light-emitting degree over an entire region having arbitrary resolution. Also, the present invention can determine a light-emitting level through a small amount of calculations without a significant error using data extraction for a partial region (a kind of sampling), not an entire region.FIG. 10is a view illustrating an example where a light-emitting level is detected in an organic light-emitting display device according to the present invention, andFIG. 11is a view illustrating another example where a light-emitting level is detected in an organic light-emitting display device according to the present invention.

FIG. 11illustrates a case where data of above ⅓ level compared to a case ofFIG. 10are sampled and detected. Tables 1 and 2 show that an error of less than about 1% is generated. Table 1 shows results extracted fromFIG. 10, and Table 2 shows results extracted fromFIG. 11.

TABLE 1The number of pixelsRatioBlue650.0903White1500.2083total7201.0000

TABLE 2The number of pixelsRatioBlue210.0875White480.2000total2401.0000

An organic light-emitting display device having the above-described structure can be used for a mobile communication terminal and remarkably reduce power consumption. Also, the organic light-emitting display device can be used for image display devices such as computer monitors, televisions, and electronic display boards, and remarkably reduce power consumption.

The mobile communication terminal includes the above-described organic light-emitting display device, a communication element performing communication with the outside, and a controller controlling the communication element and displaying by the organic light-emitting display device.

The image display devices include the above-described organic light-emitting display device and a controller transmitting video signals to the organic light-emitting display device.

Industrial Applicability

According to an organic light-emitting display device and a driving method thereof, there is an advantage of managing power consumption below a set value regardless of a light emitting area and a light emitting degree of a light-emitting unit having organic light-emitting devices.