Patent Application
20070126671
This application claims priority to and the benefit of Korean Patent Application No. 10-2005-0117176, filed on Dec. 2, 2005, in the Korean Intellectual Property Office, the entire content of which is incorporated herein by reference.
1. Field of the Invention
The present invention relates to an organic light emitting display device and a driving method thereof, and more particularly, to an organic light emitting display device, which can individually (or freely or arbitrarily) control light emission times of red, green and blue subpixels, and a driving method thereof.
2. Discussion of Related Art
An organic light emitting display device is a flat panel display device that uses organic light emitting diodes to emit light by re-combination of electrons and holes. The organic light emitting display device has high response speed and low power consumption.
Referring to
The display region 30 includes the plurality of subpixels R, G and B that are formed in areas defined by the scan lines S1 through Sn, light emitting control lines E1 through En and the data lines D1 through Dm. Here, one pixel 40 includes one red subpixel R, one green subpixel G, and one blue subpixel B. In addition, the subpixels R, G and B are arranged along one horizontal line. In other words, the red, green and blue subpixels R, G and B are alternately and repeatedly arranged along a first horizontal line to be connected with the first scan line S1.
The red subpixel R generates a red light corresponding to a data signal. For achieving this, a red organic light emitting diode (not shown in
First and second powers of first and second power sources ELVDD and ELVSS are applied to each of the subpixels R, G and B. The subpixels R, G and B to which the first and second powers of the first and second power sources ELVDD and ELVSS are applied provide a current that corresponds to a data signal through the organic light emitting diodes from the first power source ELVDD to the second power source ELVSS.
The timing control part 50 generates a data driving signal DCS and a scan driving signal SCS corresponding to synchronizing signals. The data driving signal DCS generated from the timing control part 50 is provided to the data driver 20, and the scan driving signal SCS is provided to the scan driver 10.
The scan driver 10 receives the scan driving control signal SCS. The scan driver 10, which receives the scan driving control signal SCS, sequentially provides a scanning signal to the scan lines S1 through Sn for every horizontal time period. Also, the scan driver 10, which receives the scan driving control signal SCS, sequentially provides a light emitting control signal to light emitting control lines E1 through En. Here, the width of the light emitting control signal is set to be equal to or broader than that of the scanning signal.
The data driving signal DCS is provided from the timing control part 50 to the data driver 20. The data driver 20 that receives the data driving signal DCS provides a data signal to the data lines D1 through Dm for every horizontal period.
In this prior organic light emitting display device, the light emitting efficiency and the durability characteristic of the red organic light emitting diode included in the red subpixel R, the light emitting efficiency and the durability characteristic of the green organic light emitting diode included in the green subpixel G, and the light emitting efficiency and the durability characteristic of the blue organic light emitting diode included in the blue subpixel B are different from one another. In other words, according to the materials used, light emitting efficiencies and/or durability characteristics of the red, green and blue organic light emitting diodes are different from one another. Therefore, the light emission times of the red, green and blue organic light emitting diodes need to be properly controlled. However, in the prior art, since the red, green and blue subpixels R, G and B of one pixel 40 are connected with only one scan line S, there is a problem in that each of the light emission times of the red, green and blue subpixels R, G and B could not be individually controlled.
Accordingly, it is an aspect of the present invention to provide an organic light emitting display device, which can individually control light emission times of the red, green and blue subpixels and a driving method thereof.
In one embodiment of the present invention, an organic light emitting display device includes a plurality of subpixels arranged in a plurality of horizontal lines and a plurality of vertical lines; a plurality of scan lines and a plurality of light emitting control lines connected with the subpixels and formed along the horizontal lines; and a plurality of data lines connected with the pixels and formed along the vertical lines. Here, the subpixels arranged along one of the horizontal lines generate lights of a same color.
In one embodiment of the present invention, an organic light emitting display device includes a plurality of subpixels connected with scan lines, light emitting control lines, and data lines; a scan driver for driving the scan lines and the light emitting control lines; and a data driver for driving the data lines. Here, the subpixels connected with one of the light emitting control lines generate lights of a same color.
In one embodiment of the present invention, a method of driving an organic light emitting display device is provided. The method includes: controlling a light emission time of a plurality of first subpixels placed along a first horizontal line to generate a light of a first color; controlling a light emission time of a plurality of second subpixels placed along a second horizontal line to generate a light of a second color; and controlling a light emission time of a plurality of third subpixels placed along a third horizontal line to generate a light of a third color. Here, the light emission times of the first, second, and third subpixels are set to correspond to at least one of a light emitting efficiency of the first, second, and third subpixels or a durability characteristic of the first, second, and third subpixels.
The accompanying drawings, together with the specification, illustrate exemplary embodiments of the present invention, and, together with the description, serve to explain the principles of the present invention.
In the following detailed description, certain exemplary embodiments of the present invention are shown and described, by way of illustration. As those skilled in the art would recognize, the described exemplary embodiments may be modified in various ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature, rather than restrictive. There may be parts shown in the drawings, or parts not shown in the drawings, that are not discussed in the specification as they are not essential to a complete understanding of the invention. Like reference numerals designate like elements. Here, when a first element is connected to/with a second element, the first element may be not only directly connected to/with the second element but also indirectly connected to/with the second element via a third element.
Referring to
The display region 130 includes the plurality of subpixels R, G and B that are formed in areas defined by the scan lines S1 through Sn, the light emitting control lines E1 through En and the data lines D1 through Dm. Here, one pixel 140 includes one red subpixel R, one green subpixel G, and one blue subpixel B. In addition, the subpixels R, G and B for emitting (or generating) one (or the same) color (e.g., red, green, or blue) are arranged to be connected with one scan line S and one light emitting control line E.
For example, the first scan line S1 and the first light emitting control line E1 are connected with the red subpixels R, the second scan line S2 and the second light emitting control line E2 are connected with the green subpixels G, and the third scan line S3 and the third light emitting control line E3 are connected with the blue subpixels B. That is, according to the present invention, the subpixels R, G and B are arranged such that the respective subpixels R, G and B for generating the same color are arranged along one horizontal line.
In the above example, the red subpixels R generate a red light corresponding to the data signal that is provided from the data lines D1 through Dm. To achieve this, each of the red subpixels R includes red organic light emitting diodes. Also, a light emission time of the red subpixels R is controlled by the light emitting control signal that is provided from the light emitting control line E1 connected with the red subpixels R.
The green subpixels G generate a green light corresponding to the data signal that is provided from the data lines D1 through Dm. To achieve this, each of the green subpixels G includes green organic light emitting diodes. Also, a light emission time of the green subpixels R is controlled by the light emitting control signal that is provided from the light emitting control line E2 connected with the green subpixels G.
The blue subpixels B generate a blue light corresponding to the data signal that is provided from the data lines D1 through Dm. To achieve this, each of the blue subpixels B includes blue organic light emitting diodes. Also, a light emission time of the blue subpixels B is controlled by the light emitting control signal that is provided from the light emitting control line E3 connected with the blue subpixels B.
The timing control part 150 generates a data driving signal DCS and a scan driving signal SCS corresponding to synchronizing signals. The data driving signal DCS generated from the timing control part 150 is provided to the data driver 120, and the scan driving signal SCS is provided to the scan driver 110.
The scan driver 110 receives the scan driving control signal SCS. The scan driver 110, which receives the scan driving control signal SCS, sequentially provides a scanning signal to the scan lines S1 through Sn for every horizontal time period. Also, the scan driver 110, which receives the scan driving control signal SCS, sequentially provides a light emitting control signal to light emitting control lines E1 through En. Here, the width of the light emitting control signal may be determined by a light emitting efficiency and/or a durability characteristic.
The data driving signal DCS is provided from the timing control part 150 to the data driver 120. The data driver 120 that receives the data driving signal DCS provides a data signal to the data lines D1 through Dm for every horizontal period. Here, because the red subpixel R, the green subpixel G, and the blue subpixel B are alternately and repeatedly arranged for every vertical line, the data driver 120 alternately and repeatedly provides a red data signal DS(R), a green data signal. DS(G), and a blue data signal DS(B) to each of the data lines D1 through Dm as shown in
Referring to
The organic light emitting diode OLED generates a light of a luminance corresponding to the amount of current provided thereto, wherein the luminance may be predetermined. Here, a red organic light emitting diode OLED(R) included in the red subpixel R generates a red light corresponding to the amount of current, a green organic light emitting diode OLED(G) included in the green subpixel G generates a green light corresponding to the amount of current, and a blue organic light emitting diode OLED(B) included in the blue subpixel B generates a blue light corresponding to the amount of current.
The gate of the first transistor M1, which is included in each of the subpixels R, G, B, is connected with the scan line S (e.g., one of the scan lines S1, S2, S3, etc.), the first electrode of the first transistor M1 is connected with the data line D (e.g., one of the data lines D1, D2, D3, etc.), and the second electrode of the first transistor M1 is connected with a first electrode of the storage capacitor C and the gate of the second transistor M2. The first transistor M1 is turned on to thereby provide the data signal provided from the data line D to the storage capacitor C when the scan signal is provided form the scan line S to the first transistor M1. At this time, the storage capacitor C is charged with a voltage corresponding to a voltage difference between the data signal and a first power (or voltage) of a first power source ELVDD. That is, when the data signal is provided to the storage capacitor C, the storage capacitor C is charged with a voltage corresponding to a voltage difference between the data signal and the first power of the first power source ELVDD.
The gate of the second transistor M2 is connected with the first electrode of the storage capacitor C, the first electrode of the second transistor M2 is connected with the first power source ELVDD, and the second electrode of the second transistor M2 is connected with the first electrode of the third transistor M3. The second transistor M2 controls the amount of current flowing from the first power source ELVDD to the light emitting diode OLED corresponding to the voltage charged in the storage capacitor C.
The gate of the third transistor M3 is connected with the light emitting control line E (e.g., one of the light emitting control lines E1, E2, E3, etc.), the first electrode of the third transistor M3 is connected with the second electrode of the second transistor M2, and the second electrode of the third transistor M3 is connected with the organic light emitting diode OLED. The third transistor M3 is turned on to provide a current from the second transistor M2 to the organic light emitting diode OLED when the light emitting control signal is not provided to the third transistor M3 (or when the light emitting control signal is not at a high level). That is, the third transistor M3 controls a time that a current is provided from the second transistor M2 to the organic light emitting diode OLED.
Referring to
When the scan signal is provided to the first scan line S1 (or is at a low level), the first transistor M1, which is included in the subpixels R connected with the first scan line S1, is turned on. At this time, the data signal, which is provided to the data lines D1 through Dm, is provided to the subpixels R connected with the first scan line S1. Then, the storage capacitor C is charged with a voltage corresponding to the data signal.
In
In addition, the storage capacitor C, which is included in each subpixel G connected with the second scan line S2, is charged with the voltage corresponding to the data signal by the scan signal and the light emitting control signal respectively provided to the second scan line S2 and the second light emitting control line E2, and a green light (e.g., a green light of a predetermined luminance) is emitted from the organic light emitting diode OLED(G) corresponding to the voltage stored by the storage capacitor C.
Also, the storage capacitor C, which is included in each subpixel B connected with the third scan line S3, is charged with the voltage corresponding to the data signal by the scan signal and the light emitting control signal respectively provided to the third scan line S3 and the third light emitting control line E3, and a blue light (e.g., a blue light of a predetermined luminance) is emitted from the organic light emitting diode OLED(B) corresponding to the voltage stored by the storage capacitor C.
As such, by repeating the above processes, the subpixels R, G and B display an image on the display region 130.
In view of the above, since the subpixels connected with one light emitting control line E generate lights of the same color, the light emission times of red, green and blue lights can be individually (or independently or freely) controlled by using the light emitting control signal. In other words, according to the present invention, the light emission times of the red, green and blue subpixels R, G and B can be individually (or independently or arbitrarily) controlled.
For example, in the present invention, considering the light emitting efficiencies of the red, green and blue organic light emitting diodes OLED(R), OLED(G) and OLED(B), the light emission times of the red, green and blue subpixels R, G and B can be controlled. That is, the light emission time of a subpixel including an organic light emitting diode having a higher light emitting efficiency is set shorter than that of a subpixel including an organic light emitting diode having a lower light emitting efficiency, such that a white balance of an image is properly adjusted to be displayed.
In one embodiment, according to the characteristics of materials used for the red, green and blue organic light emitting diodes OLED(R), OLED(G) and OLED(B), the light emitting efficiency of the green subpixel G is the highest and the light emitting efficiencies of the red and blue subpixels R and B are similar to each other.
Therefore, considering the above described light emitting efficiencies of the red, green and blue organic light emitting diodes OLED(R), OLED(G) and OLED(B), the widths of light emitting control signals are set as shown in
Referring to
In addition, considering durability characteristics of the red, green and blue organic light emitting diodes OLED(R), OLED(G) and OLED(B), the light emission times of the red, green and blue subpixels R, G and B can be controlled. In other words, the light emission time of a subpixel having a longer durability characteristic is set longer than that of the light emission time of a subpixel having a shorter durability characteristic, such that the durability of subpixels may be set to be similar to one another.
For example, if the durability of the blue organic light emitting diode OLED(B) is the shortest, and the durability of the red and green organic light emitting diode OLED(R) and OLED(G) are similar to each other, the width of the light emitting control signal can be set as shown in
Referring to
That is, according to the present invention, by controlling the width of the light emitting control signal as occasion demands, the light emission times of the red, green and blue subpixels R, G and B can be freely controlled.
A structure of a subpixel according to embodiments of the present invention can be modified with various suitable subpixel structures having a transistor controlled by a light emitting control signal, and the present invention is not limited by the above described embodiments.
Referring to
The organic light emitting diode OLED generates a light having a luminance corresponding to the amount of current provided to the organic light emitting diode OLED, wherein the luminance may be predetermined. Here, a red organic light emitting diode OLED(R) included in a red subpixel R generates a red light corresponding to the amount of current, and a green organic light emitting diode OLED(G) included in a green subpixel R generates a green light corresponding to the amount of current, and a blue organic light emitting diode OLED(B) included in a blue subpixel B generates a blue light corresponding to the amount of current.
The first electrode of the second transistor M2′ is connected with a data line Dm, and the second electrode of the second transistor M2′ is connected with a first node N1. The gate of the second transistor M2′ is connected with an n-th scan line Sn. The second transistor M2′ is turned on to provide a data signal provided to the data line Dm to the first node N1 when a scan signal is provided to the n-th scan line Sn.
The first electrode of the first transistor M1′ is connected with the first node N1, and the second electrode of the first transistor M1′ is connected with the first electrode of the sixth transistor M6. The gate of the first transistor M1′ is connected with the storage capacitor C′. The first transistor M1′ provides the organic light emitting diode OLED with a current corresponding to the voltage charged in the storage capacitor C′.
The first electrode of the third transistor M3′ is connected with the second electrode of the first transistor M1′, and the second electrode of the third transistor M3′ is connected with the gate of the first transistor M1′. The gate of the third transistor M3′ is connected with the n-th scan line Sn. The third transistor M3′ is turned on to allow the first transistor M1′ to be diode-connected (or is turned to electrically connect the gate of the first transistor M1′ and the second electrode of the first transistor M1′ with each other) when the scan signal is provided to the n-th scan line Sn.
The first electrode of the fourth transistor M4 is connected with an (n−1)th scan line Sn−1, and the second electrode of the fourth transistor M4 is connected with the storage capacitor C′ and the gate of the first transistor M1′. The fourth transistor M4 is turned on to reset the gate of the first transistor M1′ and the storage capacitor C′ when the scan signal is provided to the (n−1)th scan line Sn−1.
The first electrode of the fifth transistor M5 is connected with a first power source ELVDD, and the second electrode of the fifth transistor M5 is connected with the first node N1. The gate of the fifth transistor M5 is connected with a light emitting control line En. The fifth transistor M5 is turned on to allow the first power source ELVDD and the first node N1 to be electrically connected with each other when the light emitting control signal is not provided from the light emitting control line En.
The first electrode of the sixth transistor M6 is connected with the second electrode of the first transistor M1′, and the second electrode of the sixth transistor M6 is connected with the anode of the organic light emitting diode OLED. The gate of the sixth transistor M6 is connected with the light emitting control line En. The sixth transistor M6 is turned on to provide a current from the first transistor M1′ to the organic light emitting diode OLED when the light emitting control signal is not provided to the sixth transistor M6.
Explaining the operation process in brief, the scan signal is provided to the (n−1)th scan line Sn−1, such that the fourth transistor M4 is turned on. When the fourth transistor M4 is turned on, the storage capacitor C′ and the first transistor M1′ are connected with the (n−1)th scan line Sn−1. Then, the storage capacitor C′ and the gate of the first transistor M1′ are reset with the voltage of the scan signal. Here, the voltage value of the scan signal is set to be lower than that of the data signal.
Next, the scan signal is provided to the n-th scan line Sn. When the scan signal is provided to the n-th scan line Sn, the second and third transistors M2′ and M3′ are turned on. When the second transistor M2′ is turned on, the first transistor M1′ is diode-connected by the transistor M3′. When the second transistor M2′ is turned on, the data signal provided to the data line Dm is provided through the second transistor M2′ to the first node N1. At this time, since the gate voltage of the first transistor M1′ is initialized by the scan signal (i.e., the gate voltage is set to be lower than that of the data signal provided to the first node N1), the first transistor M1′ is turned on.
When the first transistor M1′ is turned on, the data signal that is applied to the first node N1 is provided through the first and third transistors M1′ and M3′ to the storage capacitor C′. Here, since the data signal is provided through the first transistor M1′, which is diode-connected, to the storage capacitor C′, the storage capacitor C′ is charged with a voltage corresponding to the data signal and a threshold voltage of the first transistor M1′. After charging the storage capacitor C′ with the voltage corresponding to the data signal and the threshold voltage of the first transistor M1′, the supply of the light emitting control signal (e.g., EM1) is ceased for a particular time period, such that fifth and sixth transistors M5 and M6 are turned on. Here, the time period for supplying the light emitting control signal (e.g., EM1) is set by considering the durability characteristic and/or efficiency characteristic of the organic light emitting diode OLED. That is, the first transistor M1′ controls the current flowing from the first power source ELVDD to the organic light emitting diode OLED corresponding to the voltage charged to the storage capacitor C′.
As mentioned above, in an organic light emitting display device and driving method thereof, by connecting subpixels for generating one color with one of the light emitting control lines (i.e., by arranging a set of the subpixels for generating the same color along one horizontal line, the light emission times of the subpixels for generating different colors can be independently or freely controlled). Indeed, according to embodiments of the present invention, the light emission time of the subpixels can be controlled by considering the light emitting efficiency and/or durability characteristic of the organic light emitting diodes in the subpixels.
While the invention has been described in connection with certain exemplary embodiments, it is to be understood by those skilled in the art that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications included within the spirit and scope of the appended claims and equivalents thereof.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2005-117176 | Dec 2005 | KR | national |
