KR100756479B1 - A light-emitting device for preventing the moir effect and driving method in the same - Google Patents

Abstract

A light-emitting device for preventing MOIRE effect and a driving method thereof are provided to reduce the brightness difference between two ends of scan lines by repeating a process of changing the direction of scan signals every driving frame of pixels so that a bright part of a present frame gets dark at another frame. A light-emitting device for preventing MOIRE effect comprises a plurality of pixels(206), a plurality of scan lines(214a,214b), first and second switches(216a,216b), and a switch driving unit(226). The pixels are formed at a light emitting area in which an anode electrode layer(202) and a cathode electrode layer(204) cross each other. The switches are placed between two ends of the cathode electrode layer and the scan lines to switch the cathode electrode layer and the scan lines. The switch driving unit turns on one of the first and second switches in each scan line when driving the pixels.

Description

Light-Emitting DEVICE FOR PREVENTING THE MOIR EFFECT AND DRIVING METHOD IN THE SAME

1A is a plan view schematically illustrating a panel of a conventional light emitting device.

FIG. 1B is a circuit diagram illustrating the organic EL device of FIG. 1A.

FIG. 1C is a circuit diagram illustrating some pixels of FIG. 1B.

2A is a plan view schematically illustrating a panel of another conventional light emitting device.

FIG. 2B is a circuit diagram illustrating the organic EL device of FIG. 2A.

3A is a plan view schematically illustrating a light emitting device according to an exemplary embodiment of the present invention.

3B is a circuit diagram illustrating the light emitting device of FIG. 3A.

4A and 4B are circuit diagrams illustrating an embodiment of a method of driving the light emitting device of FIG. 3B.

5A and 5B are circuit diagrams illustrating another embodiment of the method of driving the light emitting device of FIG. 3B.

The present invention relates to a light emitting device for preventing streaks and a driving method thereof.

FIG. 1A is a plan view schematically illustrating a panel of a conventional light emitting device, FIG. 1B is a circuit diagram illustrating the organic EL device of FIG. 1A, and FIG. 1C is a circuit diagram illustrating some pixels of FIG. 1B.

Referring to FIG. 1A, a panel 100a of a conventional light emitting device is a stripe-typed panel, and is formed in a plurality of light emitting regions where the anode electrode layers 102 and the cathode electrode layers 104 intersect. Pixels 106. Here, the pixels 106 include an anode electrode layer 102, an organic material layer, and a cathode electrode layer 104 sequentially stacked on a substrate.

The data lines 112 are connected to the anode electrode layers 102 and provide the pixels 106 with data current transmitted from an integrated circuit chip (not shown).

The scan lines 114a and 114b are connected to one end of the cathode electrode layers 104 and transmit scan signals transmitted from the integrated circuit chip to the cathode electrode layers 104.

The integrated circuit chip is connected to the lines 112, 114a and 114b, and drives signals through the data lines 112 and the scan lines 114a and 114b to drive signals for driving the pixels 106. To be sent). As a result, the pixels 106 generate light having a predetermined wavelength.

Hereinafter, a driving process of the panel 100a configured as shown in FIG. 1A will be described in detail.

1B and 1C, when pixels corresponding to one scan line of pixels E11 to E64 emit light, the scan line is connected to ground, and the remaining scan lines are pixels E11 to E64. It is connected to a voltage (V1) of the same magnitude as the driving voltage for driving the.

Hereinafter, the relationship between the pixels E11 to E64 will be described in detail by taking the case where the first scan line S1 or the second scan line S2 is grounded as an example. In this case, it is assumed that the resistance between the outermost pixels E11 and E61 and the ground is 1Ω, and the resistance of the line between the pixels E11 to E61 is 0.2Ω. In addition, the driving voltages of the pixels E11 to E61 are referred to as 18V, and the data currents I1 to I6 are referred to as 1A.

The first resistance value R11 between the first pixel E11 and the ground is 1 Ω, as shown in FIG. 1C, and the first current source receives the first data current I1 having 1A as the first data line D1. It provides to the first pixel E11 through. In this case, in the panel 100a of FIG. 1A, since the resistance values of the scan lines S1 to S4 are assumed to be 1 Ω, 1A is applied to the first pixel E11 so that the first pixel E11 has a desired luminance. It emits light.

The second resistance value R21 between the second pixel E21 and the ground is 1.2 Ω, and the second pixel is connected to the second data current I2 having 1A through the second data line D2. It is provided to (E21). In this case, since the second resistance value R2 is larger than 1 Ω, the cathode voltages of the pixels E11 and E21 when the same magnitude of data currents I1 and I2 are provided to the pixels E11 and E21. That is, the cathode voltages were different. In general, the greater the cathode voltage, the darker the pixel will be. Therefore, since the cathode voltage of the pixel E21 is greater than the cathode voltage of the pixel E11, the pixel E21 emits light darker than the pixel E11.

When the resistance values between the pixels E31 to E61 and the ground are calculated in this manner, the resistance values increase toward the sixth pixel E61 as shown in FIG. 1C, and as a result, the sixth pixel ( E61) emitted light at the lowest luminance.

Hereinafter, the pixels E12 to E62 corresponding to the second scan line S2 will be described.

The resistance values between the pixels E12 to E62 corresponding to the second scan line S2 and the ground become larger toward the seventh pixel E12 as shown in FIG. 1C, and thus the seventh pixel E12. This emitted the darkest light.

Hereinafter, the pixels E11 to E61 corresponding to the first scan line S1 and the pixels E12 to E62 corresponding to the second scan line S2 will be compared.

The first resistance value R11 corresponding to the first pixel E11 corresponding to the first scan line S1 and the seventh resistance value R12 of the seventh pixel E12 corresponding to the second scan line S2. ) Is different. That is, the magnitude of the cathode voltage of the pixel E11 and the cathode voltage of the pixel E21 are different. Therefore, when the same currents are provided to the pixels E11 and E21, a contrast difference occurs between the first pixel E11 and the seventh pixel E12.

In this way, when comparing the pixels E11 to E61 corresponding to the first scan line S1 and the pixels E12 to E62 corresponding to the second scan line S2, the first scan line S1. ) And a contrast difference occurs between the pixels E11 to E61 corresponding to) and the pixels E12 to E62 corresponding to the second scan line S2. As a result, the first scan line S1 and the second scan line S2 form stripes.

That is, when the scan lines 114a and 114b are formed as shown in FIG. 1A, the stripes may be formed by contrast.

In order to prevent such streaks from being formed, methods for driving the scan lines 114a and 114b in various ways have been proposed.

FIG. 2A is a plan view schematically showing a panel of another conventional light emitting device, and FIG. 2B is a circuit diagram showing the organic EL device of FIG. 2A.

Referring to FIGS. 2A and 2B, the panel 100b is identical to the panel of FIG. 1A in which scan lines 114a and 114b are connected to one end of the cathode electrode layers 104, but is even as in the panel of FIG. 1A. The difference between forming the first scan lines and the odd scan lines in the opposite direction and forming the wirings of the upper scan lines 114a and the lower scan lines 114b in the opposite direction. The other structure is the same as that of the panel of FIG.

When the scan lines are formed in this way, no contrast difference occurs between the scan lines S1 and S2 of the upper end, so that stripes are not formed. Also, no stripes are formed between the scan lines S3 and S4 at the lower end.

However, at the interface (between S2 and S3) of the upper end and the lower end, stripes can be formed on the same principle as described in FIGS. 1B and 1C.

As such, the conventional light emitting device is a method of repeatedly driving the scan lines 114a and 114b formed in a specific direction, and thus there is a limit to the improvement of the stripes.

Therefore, there is a need for a light emitting element capable of preventing the formation of stripes by the contrast difference between the scan lines.

An object of the present invention is to prevent the formation of stripes by connecting the scan lines to both ends of the cathode electrode layers, by forming a switch at each end to change the direction in which the scan signal is applied to each drive frame of the pixels differently. A light emitting device and a driving method thereof are provided.

In addition, an object of the present invention is to change the direction in which the scan signal is applied to each drive frame of the pixels to repeat the process so that the portion that appears bright in the current frame is dark in another frame to smooth the difference in brightness across the scan lines The present invention provides a light-emitting device for preventing streaks and a driving method thereof.

In order to achieve the above object, a light emitting device for preventing streaks according to an exemplary embodiment of the present invention includes a plurality of pixels, a plurality of scan lines, formed in light emitting regions where the anode electrode layers and the cathode electrode layers intersect. A plurality of first and second switches positioned between both ends of the cathode electrode layers and the scan lines to switch the cathode electrode layers and the scan lines and the pixels when the pixels are driven; A switch driver for turning on any one of the two switches.

In addition, in a method of driving a light emitting device including a plurality of pixels formed in light emitting regions where anode electrode layers and cathode electrode layers intersect, the cathode during one frame of driving the pixels Applying scan signals to the pixels through the first scan lines of a plurality of first and second scan lines connected across the electrode layers and during the next frame driving the pixels, the second scan lines And applying the scan signals to the pixels via.

In the anti-stripe light emitting device according to the present invention and a driving method thereof, the scan lines are connected to both ends of the cathode electrode layers, and switches are formed at both ends to change the direction in which the scan signal is applied to each driving frame of the pixels, thereby forming stripes. Can be prevented.

Hereinafter, with reference to the accompanying drawings will be described in detail preferred embodiments of the light-emitting device for preventing streaks and the driving method according to the present invention.

3A is a plan view schematically illustrating a light emitting device according to an exemplary embodiment of the present invention, and FIG. 3B is a circuit diagram illustrating the light emitting device of FIG. 3A.

Referring to FIG. 3A, a light emitting device according to the present invention includes a panel 200 and a driver 220. Here, the light emitting device according to an embodiment of the present invention is an organic electroluminescent device.

The panel 200 includes a plurality of pixels 206, a plurality of scan lines 214a and 214b, and a plurality of data lines formed in light emitting regions where the anode electrode layers 202 and the cathode electrode layers 204 intersect. And 212 and a plurality of first and second switches 216a and 216b.

The pixels 206 include an anode electrode layer 202, an organic material layer, and a cathode electrode layer 204 sequentially stacked on a substrate. The organic layer may include a hole transporting layer (HTL), an emission layer (EML), and an electron transport layer (ETL).

The data lines 212 are connected to the anode electrode layers 202 and provide the pixels 206 with a data current transmitted from the data driver 222 which will be described below.

Scan lines 214a and 214b are connected to both ends of each of the cathode electrode layers 204 and provide scan signals transmitted from scan drivers 224a and 224b to the pixels 206 to be described below. The scan signals are transmitted to the pixels 206 through the selected one-way scan lines 214a or 214b of the scan lines 214a and 214b.

The first switches 216a are connected between one end of each of the cathode electrode layers 204 and the scan lines 214a, and the second switches 216b are connected to the other end of each of the cathode electrode layers 204 and the scan lines. 214b.

When the first and second switches 216a and 216b are turned on, the scan signals may be transmitted to the pixels 206 through the scan lines 214a and 214b.

The driver 220 includes a data driver 222, scan drivers 224a and 224b, a switch driver 226, and a drive controller 228.

The drive controller 228 controls the scan drivers 224a and 224b, the data driver 222, and the switch driver 226. In particular, according to the driving method of the panel 200, the scan lines 214a and 214b to which the scan signals are to be transmitted are determined to transmit scan control signals to the scan drivers 224a and 224b, and the scan drivers 224a and 224b. A switch driving signal for turning on selected ones of the first and second switches 216a and 216b connected to the respective cathode electrode layers 204 is transmitted to the switch driver 226 in response to the driving of.

The scan drivers 224a and 224b transmit scan signals to the scan lines 214a and 214b under the control of the drive controller 228. As a result, scan lines 214a and 214b are sequentially connected to ground.

The data driver 222 provides the data lines corresponding to the display data to the data lines 212 under the control of the driving controller 228. As a result, pixels 206 corresponding to the scan line connected to the ground emit light.

The switch driver 226 turns on one of the first and second switches 216a and 216b connected to the respective cathode electrode layers 204 under the control of the drive controller 228, and turns off the other convenience switches. Let's do it.

Hereinafter, the driving operation of the light emitting device of the present invention will be described in detail.

Referring to FIG. 3B, the switch driver 226 turns on any one of the first and second switches 216a and 216b under the control of the drive controller 228. Accordingly, the scan lines S1 to S4 connected to the on switches (first switch or second switch 216a or 216b) among the scan lines S1 to S4 connected to both ends of the cathode electrode layers 204. Only the pixels 206 are connected.

The scan drivers 224a and 224b transmit the scan signals to the scan lines S1 to S4 connected to the switches maintaining the on state under the control of the driving controller 228.

The data driver 222 transmits a data current corresponding to the display data to the data lines D1 to D6 under the control of the driving controller 228. As a result, pixels E11 to E64 emit light during the low logic of the scan signals.

In this way, the light emitting element is driven for one frame.

Subsequently, during the next frame, the switch driver 226 turns off the switches that were turned on in the previous frame and turns on the switches that were turned off under the control of the drive controller 228.

Accordingly, scan lines S1 to S4 at the other end, which are not connected to the respective cathode electrode layers 204 in the previous frame, are connected to the pixels 206.

Subsequently, the scan drivers 224a and 224b transmit the scan signals to the scan lines S1 to S4 connected to the switches maintaining the on state, and the data driver 222 transmits data current corresponding to the display data. Transfer to lines D1 through D6. As a result, pixels E11 to E64 emit light during the low logic of the scan signals.

As such, the switches connected to one end of each cathode electrode layer 204 are turned on in the first frame to transmit scan signals through the scan lines connected to the switches, and the switches connected to the other end of each cathode electrode layer 204 in the second frame. By repeatedly turning on, the scan signals are transmitted through the scan lines connected to the switches for each frame.

That is, the directions of the scan lines S1 to S4 through which scan signals are transmitted are changed for each frame.

There are various ways to set the direction in which the pixels 206 and the scan lines S1 to S4 are connected by controlling the on / off of the first and second switches 216a and 216b. It is not limited to.

4A and 4B are circuit diagrams illustrating an embodiment of a method of driving the light emitting device of FIG. 3B.

First, during the first frame, the switch driver 226 turns on the first switches 216a and turns off the second switches 216b under the control of the drive controller 228. Accordingly, the scan lines S1 to S4 are connected to the left side of the cathode electrode layers 204 as shown in FIG. 4A.

The scan driver 224a transmits scan signals through the connected scan lines S1 to S4, and the data driver 222 applies the data currents to the data lines D1 to D6 to drive the pixels 206. do.

Next, during the second frame, the switch driver 226 turns off the first switches 216a and turns on the second switches 216b under the control of the drive controller 228. Accordingly, the scan lines S1 to S4 are connected to the right side of the cathode electrode layers 204 as shown in FIG. 4B.

Hereinafter, scan signals and data currents are applied in the same manner to drive the pixels 206.

The third frame is driven again in the same manner as the first frame, and the fourth frame is repeatedly driven in the same manner as the second frame.

As a result, a relatively bright part of the first frame appears dark in the second frame. As such, the light and dark states are repeated for each frame, thereby reducing the difference in brightness across the cathode electrode layers 204. That is, in the conventional light emitting device, one end of each cathode electrode layer is bright and the other end is dark, but the light emitting device of the present invention is one end of each cathode electrode layer is less bright than the conventional, and the other end is less dark than the conventional.

Accordingly, the difference in brightness between both ends of one cathode electrode layer and both ends of another neighboring cathode electrode layer is reduced as compared with the conventional light emitting device. Therefore, the panel 200 of the present invention, unlike the panel in the conventional organic EL device is reduced the phenomenon that the stripes appear.

5A and 5B are circuit diagrams illustrating another embodiment of the method of driving the light emitting device of FIG. 3B.

First, during the first frame, the switch driver 226 may control the first switches 216a and the even scan lines S2 and S4 connected to the odd scan lines S1 and S3 under the control of the driving controller 228. Turn on the second switches 216b connected thereto and turn off the remaining switches. Accordingly, the scan lines S1 to S4 are in a connected state as shown in FIG. 5A.

The scan driver 224a and 224b transmit the scan signals through the connected scan lines S1 to S4, and the data driver 222 applies data currents to the data lines D1 to D6 to provide the pixels 206. To drive.

Next, during the second frame, the switch driver 226 is connected to the second switches 216b connected to the odd scan lines S1 and S3 and the even scan lines S2 and S4 under the control of the driving controller. The first switches 216a are turned on and the other switches are turned off. Accordingly, the scan lines S1 to S4 are in a connected state as shown in FIG. 5B.

Hereinafter, scan signals and data currents are applied in the same manner to drive the pixels 206.

The third frame is driven again in the same manner as the first frame, and the fourth frame is repeatedly driven in the same manner as the second frame.

As a result, a relatively bright part of the first frame appears dark in the second frame. As such, the light and dark states are repeated every frame so that brightness differences across the cathode electrode layers 204 do not occur. Therefore, the panel 200 of the present invention, unlike the panel in the conventional organic EL device does not generate stripes.

Preferred embodiments of the present invention described above are disclosed for purposes of illustration, and those skilled in the art having various ordinary knowledge of the present invention may make various modifications, changes, and additions within the spirit and scope of the present invention. Additions should be considered to be within the scope of the following claims.

As described above, the anti-stripe light emitting device and the driving method thereof according to the present invention change the direction in which the scan signal is applied to each driving frame of the pixels so that a portion that is bright in the current frame is dark in another frame. There is an advantage that it is possible to smooth the difference in brightness across the scan lines repeatedly.

Claims (12)

A plurality of pixels formed in the light emitting regions where the anode electrode layers and the cathode electrode layers intersect; A plurality of scan lines; A plurality of first and second switches positioned between both ends of the cathode electrode layers and the scan lines to switch the cathode electrode layers and the scan lines; And And a switch driver configured to turn on any one of the first and second switches for each scan line when the pixels are driven. The method of claim 1, The switch driver may repeat the process of turning on the first switch, turning off the second switch, turning off the first switch for the next frame, and turning on the second switch during one frame in which the pixels are driven. A light emitting element characterized by the above-mentioned. The method of claim 1, The switch driver may turn on the switches connected in the first direction of the cathode electrode layer of the first and second switches, turn off the switches connected in the second direction, during the one frame in which the pixels are driven. And switching off the switches connected in the first direction of the cathode electrode layer and turning on the switches connected in the second direction. The method of claim 1, The switch driver turns on switches connected in a first direction of even-numbered cathode electrode layers and switches connected in a second direction of odd-numbered cathode electrode layers among the first and second switches during a frame in which the pixels are driven. And turning on the switches connected in the second direction of the even-numbered cathode electrode layers and the switches connected in the first direction of the odd-numbered cathode electrode layers during the next frame. The method of claim 1, Further comprising a plurality of data lines connected to the anode electrode layers, When pixels corresponding to one cathode electrode layer emit light, scan lines connected to both ends of the cathode electrode layer are connected to ground. The method of claim 1, And a scan driver configured to transmit driving signals for driving the pixels to the pixels through scan lines connected to one of the first and second switches, the scan lines connected to both ends of the cathode electrode layers. A light emitting element characterized by the above-mentioned. The method of claim 1, The light emitting device is an organic electroluminescent device. A driving method of a light emitting device comprising a plurality of pixels formed in light emitting regions where anode electrode layers and cathode electrode layers cross each other, During one frame of driving the pixels, applying scan signals to the pixels through the first scan lines of a plurality of first and second scan lines connected across the cathode electrode layers; And During the next frame of driving the pixels, applying the scan signals to the pixels via the second scan lines. The method of claim 8, And the first scan lines are connected in a first direction of the cathode electrode layers, and the second scan lines are connected in a second direction of the cathode electrode layers. The method of claim 8, The first scan lines are connected in a first direction of even-numbered cathode electrode layers and in a second direction of odd-numbered cathode electrode layers among the cathode electrode layers, and the second scan lines are in a second direction and odd number of the even-numbered cathode electrode layers. And a second cathode electrode layer connected in a first direction. The method of claim 8, A plurality of switches are connected between both ends of the cathode electrode layers and the first and second scan lines, so that the switches connected to one of the scan lines through which the scan signals are transmitted are transmitted. A method of driving a light emitting device, characterized in that the on. The method of claim 8, The light emitting device is a method of driving a light emitting device, characterized in that the organic electroluminescent device.

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