KR102653574B1 - Transparent display device - Google Patents

Abstract

A transparent display device includes: a display panel including a plurality of pixels including a transparent area and a light-emitting area in which three subpixels including a white subpixel are arranged; a gate driving circuit that supplies a scan signal to a gate line connected to pixels of each horizontal line of the display panel; a data driving circuit that supplies data voltage to a plurality of pixels; And RGB input data consisting of three colors including red, green, and blue is converted into three-color data including white for each pixel and transmitted to the data driving circuit, and the two-color data are transmitted to neighboring pixels. It may be configured to include a timing controller, which is calculated by weighting the data of the corresponding color.

Description

Transparent display device {TRANSPARENT DISPLAY DEVICE}

This specification relates to a transparent display device, and to a subpixel structure and subpixel rendering method to increase transparency.

Flat panel displays include Liquid Crystal Display (LCD), Electroluminescence Display, Field Emission Display (FED), and Quantum Dot Display Panel (QD). . Electroluminescent display devices are divided into inorganic light emitting display devices and organic light emitting display devices depending on the material of the light emitting layer. The pixels of an organic light emitting display device include organic light emitting diodes (OLEDs), which are self-emitting devices, and display images by emitting light.

Recently, research is being conducted on transparent display devices that not only display information to the user but also transmit light so that the user in front of the panel can see not only the image displayed by the panel but also the back of the panel.

Embodiments disclosed in this specification take this situation into consideration, and the purpose of this specification is to provide an optimal pixel structure and optimal ratio of subpixels to increase transparency of a transparent display device.

Another purpose of this specification is to provide a rendering method that prevents loss of display information and color distortion in a pixel structure used in a transparent display device.

A transparent display device according to an embodiment includes a display panel including a plurality of pixels including a transmissive area and a light-emitting area in which three subpixels including a white subpixel are disposed; a gate driving circuit that supplies a scan signal to a gate line connected to pixels of each horizontal line of the display panel; a data driving circuit that supplies data voltage to a plurality of pixels; And RGB input data consisting of three colors including red, green, and blue is converted into three-color data including white for each pixel and transmitted to the data driving circuit, and the two-color data are transmitted to neighboring pixels. It is characterized by including a timing controller that is calculated by weighting the data of the corresponding color.

A method of processing image data in a transparent display device according to another embodiment includes displaying image data on a transparent display device including a plurality of pixels including a transmissive region and a light-emitting region where a plurality of subpixels including a white subpixel are disposed. A first step of processing image data and converting RGB input data consisting of three colors including red, green, and blue into RGBW data consisting of four colors including red, green, blue, and white; RGBW data, RGW data including red, green, and white for a first pixel including red, green, and white subpixels, and blue, green, and white for a second pixel including blue, green, and white subpixels. A second step of converting to BGW data including, converting the red and blue color data by weighting them with the corresponding color data of neighboring pixels; And a third step of supplying and displaying RGW data and BGW data to the first pixel and the second pixel, respectively.

By providing a pixel structure consisting of three subpixels containing white, it is possible to increase the transparency of a transparent display device.

Additionally, even if a pixel structure of three subpixels containing white is used, display information loss and color distortion can be reduced.

In addition, it is possible to provide the optimal size ratio of the three subpixels that output the best image quality.

Figure 1 compares the transmittance of a pixel structure composed of 4 subpixels containing white and a pixel structure composed of 3 subpixels including white,
Figure 2 shows a pixel structure consisting of three subpixels containing white,
Figure 3 shows information loss and color distortion occurring in the pixel structure of Figure 2;
Figure 4 shows a transparent display device as a functional block;
5 shows an example of an organic light emitting pixel circuit;
Figure 6 shows signals related to driving in the pixel circuit of Figure 5;
Figure 7 shows an image processing method applied to the pixel structure of Figure 2;
Figure 8 shows the results of improving information loss and color distortion occurring in the pixel structure of Figure 2 according to the image processing method of Figure 7;
Figure 9 shows several size ratios of subpixels in the pixel structure of Figure 5;
Figure 10 shows the results of a recognition experiment for the subpixel size ratio of Figure 9.

Hereinafter, preferred embodiments will be described in detail with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known function or configuration related to the contents of this specification may unnecessarily obscure or hinder the understanding of the contents, the detailed description will be omitted.

Figure 1 compares the transmittance of a pixel structure composed of four subpixels containing white and a pixel structure composed of three subpixels containing white.

In general, organic light emitting display devices display various colors using a combination of three primary colors including R (red), G (green), and B (blue). Recently, organic light emitting display devices use four primary colors, including W (white) in addition to R (red), G (green), and B (blue), to increase brightness, reduce power consumption, and implement a wide color gamut. It is also displayed. Transparent display devices can also use four RGBW subpixels to increase brightness or reduce power consumption.

In a transparent display device, each pixel may be composed of a light-emitting area where subpixels emit light and a transmission area where subpixels are not arranged.

In a pixel structure consisting of 4 subpixels, RGBW subpixels may be sequentially arranged in the light emitting area in the vertical direction, and a transmission area without subpixels may be placed next to the light emitting area in the horizontal direction.

Figure 2 shows a pixel structure consisting of three subpixels containing white.

In order to increase the transmittance of the transparent display device, a pixel structure consisting of three subpixels containing white instead of four subpixels can be adopted, as shown in FIG. 2. In Figure 2, for example, two vertically adjacent pixels are paired and share a subpixel of an insufficient color, where one pixel is composed of three RGW subpixels and the remaining pixel is composed of three BGW subpixels. You can.

Similar to the pixel structure made up of 4 subpixels, in the pixel structure made up of 3 subpixels, a transparent region without subpixels will be placed next to the light emitting region where the 3 subpixels are placed. You can.

Figure 1 compares the transmittance of a 4-subpixel structure and a 3-subpixel structure when the display panel sizes are 55 inches, 65 inches, and 77 inches. In Figure 1, based on a 77-inch UHD panel, the 3 subpixel structure is Transmittance is 5% higher than that of the 4-subpixel structure.

Therefore, in order to increase the transmittance of the transparent display device, a pixel structure consisting of three subpixels containing white must be adopted, as shown in FIG. 2.

Meanwhile, in a structure in which three subpixels containing white form one pixel and two pixels share the color they are lacking, as shown in Figure 2, there is image data that each pixel cannot express. A pixel composed of RGW cannot express blue (B) image data, and a pixel composed of BGW cannot represent red (R) image data.

Due to the inability to express certain image data for each pixel, the ability to express lines on the screen inevitably deteriorates.

Figure 3 shows information loss and color distortion occurring in the pixel structure of Figure 2. The left side is an input image, and the right side is an output image expressed by a pixel composed of three subpixels.

In the top right picture of Figure 3, the thin line pointing downward at an angle of 45 degrees is colored green differently from the picture on the left, and in the middle right picture of Figure 3, the thin line is also blue and pointing down at an angle of 45 degrees. does not disappear and is not displayed, and the thin line pointing downward at a 45-degree angle in the bottom right picture of FIG. 3 is colored red, unlike the picture on the left.

As such, when the pixel structure of FIG. 2 is adopted to increase transparency in a transparent display device, line expressiveness is deteriorated and color distortion occurs.

This specification provides for transmitting image data that each pixel cannot express to adjacent pixels in pairs in order to reduce the deterioration of line expression and color distortion that occurs when the display panel adopts a pixel structure consisting of three subpixels. Information loss can be prevented by adopting rendering techniques.

Additionally, this specification can optimize the quality of the image displayed by the panel by adjusting the size ratio of subpixels arranged in the light emitting area.

Figure 4 shows a transparent display device as a block. The display device of FIG. 4 may include a display panel 10, a timing controller 11, a data driving circuit 12, a gate driving circuit 13, and a power supply unit 16.

The timing controller 11, data driving circuit 12, gate driving circuit 13, and power supply unit 16 of FIG. 4 may be integrated in whole or in part into a drive IC.

The screen on which the input image is displayed on the display panel 10 includes a plurality of data lines 14 arranged in the column direction (or vertical direction) and a plurality of data lines 14 arranged in the row direction (or horizontal direction). The gate lines 15 intersect, and pixels PXL are arranged in a matrix form in each intersection area to form a pixel array.

The gate line 15 supplies a first gate line 15_1 that supplies a scan signal for applying the data voltage supplied to the data line 14 to the pixel, and a light emitting signal for causing the pixel to which the data voltage is written to emit light. It may include a second gate line 15_2.

The display panel 10 includes a first power line 101 for supplying a pixel driving voltage (or high-potential power supply voltage) Vdd to the pixels PXL, and a first power line 101 for supplying a low-potential power supply voltage Vss to the pixels PXL. ), a second power line 102 for supplying the pixel circuit, and an initialization voltage line 103 for supplying an initialization voltage (Vini) for initializing the pixel circuit. The first/second power lines 101 and 102 and the initialization voltage line 103 are connected to the power supply unit 16. The second power line 102 may be formed as a transparent electrode that covers a plurality of pixels (PXL).

Touch sensors may be disposed on the pixel array of the display panel 10. Touch input can be sensed using separate touch sensors or sensed through pixels. Touch sensors are of the on-cell type or add on type, placed on the screen (AA) of the display panel (PXL) or embedded in the pixel array. It can be implemented with sensors.

In the pixel array, the pixel PXL disposed on the same horizontal line is one of the data lines 14, one of the gate lines 15 (or one of the first gate lines 15_1 and the second It is connected to one of the gate lines (15_2) to form a pixel line.

The pixel PXL is electrically connected to the data line 14 in response to the scan signal and the light emission signal applied through the gate line 15, receives the data voltage, and causes the OLED to emit light with a current corresponding to the data voltage. Pixels PXL arranged on the same pixel line operate simultaneously according to the scan signal and the light emission signal applied from the same gate line 15.

A pixel (PXL) of an organic light emitting display device includes an OLED, which is a light emitting element, and a driving element that drives the OLED by supplying current to the OLED according to a gate-source voltage (Vgs). OLED includes an anode, a cathode, and an organic compound layer formed between these electrodes.

The organic compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer. EIL), etc. may be included, but are not limited thereto. When current flows through the OLED, holes passing through the hole transport layer (HTL) and electrons passing through the electron transport layer (ETL) move to the emitting layer (EML), forming excitons, and as a result, the emitting layer (EML) can emit visible light. there is.

As shown in FIG. 2, the pixel PXL is a first pixel including a red subpixel (R), a green subpixel (G), and a white subpixel (W), or a blue subpixel (B) and a green subpixel (G). ) and a second pixel including a white subpixel (W), and the first pixel and the second pixel may form a pair and be arranged adjacent to each other in the vertical direction. Each subpixel may be implemented as a pixel circuit including an internal compensation circuit. Hereinafter, pixel means subpixel.

The pixel (PXL) receives a pixel driving voltage (Vdd), an initialization voltage (Vini), and a low-potential power supply voltage (Vss) from the power supply unit 16, and may be provided with a driving transistor, an OLED, and an internal compensation circuit. The compensation circuit may be composed of a plurality of switch transistors and one or more capacitors, as shown in FIG. 5 described below.

The timing controller 11 converts image data (RGB) composed of three colors transmitted from an external host system (not shown) into image data (WRGB) composed of four colors further including white, and further converts the converted video data (WRGB) is converted into first image data (RGW) for the first pixel and second image data (BGW) for the second pixel using the rendering technique described with reference to FIG. 7 and supplied to the data driving circuit 12. do.

The timing controller 11 receives timing signals such as the vertical synchronization signal (Vsync), horizontal synchronization signal (Hsync), data enable signal (DE), and dot clock (DCLK) from the host system and operates the data driving circuit 12 and the Control signals for controlling the operation timing of the gate driving circuit 13 are generated. The control signals include a gate control signal (GCS) for controlling the operation timing of the gate driving circuit 13 and a data control signal (DCS) for controlling the operation timing of the data driving circuit 12.

The data driving circuit 12 samples and latches the digital video data (RGW/BGW) input from the timing controller 11 based on the data control signal (DCS), converts it into parallel data, and generates a gamma reference voltage through the channels. It is converted into an analog data voltage according to , and the data voltage is supplied to the pixels (PXL) through the output channel and data lines 14. The data voltage may be a value corresponding to the gray level that the pixel will express. The data driving circuit 12 may be composed of a plurality of driver ICs.

The data driving circuit 12 may include a shift register, a latch, a level shifter, a DAC, and a buffer. The shift register shifts the clock input from the timing controller 11 and sequentially outputs clocks for sampling, and the latch samples and latches digital video data or pixel data at the sampling clock timing sequentially input from the shift register. The sampled pixel data is output simultaneously, the level shifter shifts the voltage of the pixel data input from the latch into the input voltage range of the DAC, and the DAC converts the pixel data from the level shifter into a data voltage based on the gamma compensation voltage. The data voltage output from the DAC is supplied to the data line 14 through a buffer.

The gate driving circuit 13 generates a scan signal and a light emission signal based on the gate control signal (GCS), and generates the scan signal and the light emission signal in a row sequential manner during the active period to generate the gate line 15 connected to each pixel line. Provided sequentially. The scan signal and the light emission signal of the gate line 15 are synchronized with the supply of the data voltage of the data line 14. The scan signal and the light emission signal swing between the Gate On Voltage and Gate Off Voltage.

The gate driving circuit 13 may be composed of a plurality of gate drive integrated circuits, each including a shift register, a level shifter, and an output buffer for converting the output signal of the shift register into a swing width suitable for driving the TFT of the pixel. there is. Alternatively, the gate driving circuit 13 may be formed directly on the lower substrate of the display panel 10 using a Gate Drive IC in Panel (GIP) method. In the case of the GIP method, the level shifter may be mounted on a printed circuit board (PCB), and the shift register may be formed on the lower substrate of the display panel 10.

The power supply unit 16 uses a DC-DC converter to adjust the DC input voltage provided from the host to generate the gate-on voltage required for the operation of the data driving circuit 12 and the gate driving circuit 13. , gate-off voltage, etc., and also generates the pixel driving voltage (Vdd), initialization voltage (Vini), and low-potential power supply voltage (Vss) necessary for driving the pixel array.

The host system can be an AP (Application Processor) in mobile devices, wearable devices, and virtual/augmented reality devices. Alternatively, the host system may be a main board such as a television system, set-top box, navigation system, personal computer, and home theater system, but is not limited thereto.

Figure 5 shows an example of an organic light emitting pixel circuit, and Figure 6 shows signals related to driving in the pixel circuit of Figure 5. The pixel circuit in FIG. 5 is only an example, and the pixel circuit to which embodiments of this specification are applied is not limited to FIG. 5.

The pixel circuit in FIG. 5 is an internal compensation circuit consisting of a light-emitting device (OLED), a driving device (DT) that supplies current to the light-emitting device (OLED), a plurality of switch transistors (T1 to T6), and a storage capacitor (Cst). Including, the threshold voltage (Vth) of the driving element (DT) may be sampled to compensate the gate voltage of the driving element (DT) by the threshold voltage (Vth) of the driving element (DT). Each of the driving element (DT) and the switch transistors (T1 to T6) may be implemented as a P-channel transistor, but are not limited thereto. In the case of a P-channel transistor, the gate-on voltage may be the gate low voltage (VGL) and the gate-off voltage may be the gate high voltage (VGH).

The pixel circuit in Figure 5 is for pixels placed on the nth horizontal line (or pixel line). The operation of the pixel circuit in FIG. 5 is largely divided into an initialization period (t1), a sampling period (t3), a data writing period (t4), and an emission period (t5).

In the initialization period (t1), the (n-1)th scan signal (SCAN(n-1)) for supplying data voltage to the pixels of the (n-1)th horizontal line is applied as the gate-on voltage (VGL). The fifth and sixth switch transistors T5 and T6 are turned on and the pixel circuit is initialized. After the initialization period (t1), before the nth scan signal (SCAN(n)) for controlling data supply to the current horizontal line is applied as the gate-on voltage (VGL), the (n-1)th scan signal (SCAN(n-) A hold period (t2) in which 1)) changes from the gate-on voltage (VGL) to the gate-off voltage (VGH) is provided, but the hold period (t2) corresponding to the second period may be omitted.

In the sampling period (t3), the nth scan signal (SCAN(n)) for controlling data supply to the current horizontal line is applied as the gate-on voltage (VGL), so that the first and second switch transistors (T1, T2) It is turned on, and the threshold voltage of the driving element (or driving transistor) (DT) is sampled and stored in the storage capacitor (Cst).

In the data writing period (t4), the nth scan signal (SCAN(n)) is applied as the gate-off voltage (VGH) to turn off the first and second switch transistors (T1, T2) and the remaining switch transistor (T3) to T6) are all turned off, and the voltage of the gate electrode of the driving transistor DT increases due to the current flowing through the driving transistor DT.

In the light emission period (t5), the nth light emission signal (EM(n)) is applied as the gate-on voltage (VGL) to turn on the third and fourth switch transistors (T3 and T4), thereby turning on the light emitting device (OLED). It emits light.

In order to accurately express low gray level luminance with the duty ratio of the emission signal (EM(n)), the emission signal (EM(n)) is adjusted to the gate-on voltage (VGL) and the gate during the emission period (t5). The third and fourth switch transistors T3 and T4 can repeat on/off operations by swinging between the off voltages VGH at a predetermined duty ratio.

The anode electrode of the light emitting device (OLED) is connected to the fourth node (n4) between the fourth and sixth switch transistors (T4 and T6). The fourth node (n4) is connected to the anode electrode of the light emitting device (OLED), the second electrode of the fourth switch transistor (T4), and the second electrode of the sixth switch transistor (T6). The cathode electrode of the light emitting device (OLED) is connected to the second power line 102 to which a low-potential power supply voltage (Vss) is applied. The light emitting device (OLED) emits light with a current flowing according to the voltage (Vgs) between the gate and source of the driving device (DT). The current flow of the light emitting device (OLED) is switched by the third and fourth switch transistors (T3 and T4).

The storage capacitor Cst is connected between the first power line 101 and the second node n2. The data voltage (Vdata) compensated by the threshold voltage (Vth) of the driving element (DT) is charged in the storage capacitor (Cst). Since the data voltage (Vdata) in each pixel is compensated by the threshold voltage (Vth) of the driving element (DT), the characteristic deviation of the driving element (DT) in the pixels can be compensated.

The first switch transistor T1 is turned on in response to the gate-on voltage VGL of the nth scan signal SCAN(n) and connects the second node n2 and the third node n3. The second node n2 is connected to the gate electrode of the driving element DT, the first electrode of the storage capacitor Cst, and the first electrode of the first switch transistor T1. The third node n3 is connected to the second electrode of the driving element DT, the second electrode of the first switch transistor T1, and the first electrode of the fourth switch transistor T4. The gate electrode of the first switch transistor T1 is connected to the first gate line 15_1 and receives the nth scan signal SCAN(n). The first electrode of the first switch transistor T1 is connected to the second node n2, and the second electrode of the first switch transistor T1 is connected to the third node n3.

The second switch transistor T2 is turned on in response to the gate-on voltage VGL of the nth scan signal SCAN(n) and supplies the data voltage Vdata to the first node n1. The gate electrode of the second switch transistor T2 is connected to the first gate line 31 and receives the nth scan signal SCAN(n). The first electrode of the second switch transistor T2 is connected to the data line DL to which the data voltage Vdata is applied. The second electrode of the second switch transistor T2 is connected to the first node n1. The first node n1 is connected to the second electrode of the second switch transistor T2, the second electrode of the third switch transistor T3, and the first electrode of the driving element DT.

The third switch transistor T3 is turned on in response to the gate-on voltage VGL of the light emission signal EM(n) and connects the first power line 101 to the first node n1. The gate electrode of the third switch transistor T3 is connected to the second gate line 15_2 and receives the light emission signal EM(n). The first electrode of the third switch transistor T3 is connected to the first power line 101. The second electrode of the third switch transistor T3 is connected to the first node n1.

The fourth switch transistor T4 is turned on in response to the gate-on voltage VGL of the light emitting signal EM(n) and connects the third node n3 to the anode electrode of the light emitting device OLED. The gate electrode of the fourth switch transistor T4 is connected to the second gate line 15_2 and receives the light emission signal EM(n). The first electrode of the fourth switch transistor T4 is connected to the third node (n3), and the second electrode is connected to the fourth node (n4).

The light emitting signal EM(n) controls the on/off of the third and fourth switch transistors T3 and T4 to switch the current flow of the light emitting device OLED. Controls lighting and lighting times.

The fifth switch transistor (T5) is turned on in response to the gate-on voltage (VGL) of the (n-1) scan signal (SCAN (n-1)) to initialize the second node (n2) voltage line 103 ). The gate electrode of the fifth switch transistor T5 is connected to the first gate line 15_1 that supplies a scan signal that controls supply of data voltage to the pixels of the (n-1)th horizontal line. 1) A scan signal (SCAN(n-1)) is supplied. The first electrode of the fifth switch transistor T5 is connected to the second node n2, and the second electrode is connected to the initialization voltage line 103.

The sixth switch transistor (T6) is turned on in response to the gate-on voltage (VGL) of the (n-1) scan signal (SCAN(n-1)) and connects the initialization voltage line 103 to the fourth node (n4). ). The gate electrode of the sixth switch transistor (T6) is connected to the first gate line (15_1) for the (n-1)th horizontal line and receives the (n-1)th scan signal (SCAN(n-1)). . The first electrode of the sixth switch transistor T6 is connected to the initialization voltage line 103, and the second electrode is connected to the fourth node n4.

The driving device (DT) drives the light emitting device (OLED) by controlling the current flowing through the light emitting device (OLED) according to the gate-source voltage (Vgs). The driving element DT includes a gate electrode connected to the second node n2, a first electrode connected to the first node n1, and a second electrode connected to the third node n3.

During the initialization period t1, the (n-1)th scan signal SCAN(n-1) is input as the gate-on voltage VGL. The nth scan signal (SCAN(n)) and the emission signal (EM(n)) maintain the gate-off voltage (VGH) during the initialization period (t1). Accordingly, during the initialization period t1, the fifth and sixth switch transistors T5 and T6 are turned on and the second and fourth nodes n2 and n4 are initialized to the initialization voltage Vini. A hold period (t2) may be set between the initialization period (t1) and the sampling period (t3). In the hold period (t2), the (n-1)th scan signal (SCAN(n-1)) changes from the gate-on voltage (VGL) to the gate-off voltage (VGH), and the nth scan signal (SCAN(n)) and the emission signal (EM(n)) maintains its previous state.

During the sampling period (t3), the nth scan signal (SCAN(n)) is input as the gate-on voltage (VGL). The pulse of the nth scan signal SCAN(n) is synchronized with the data voltage Vdata to be supplied to the nth pixel line. The (n-1)th scan signal (SCAN(n-1)) and the emission signal (EM(n)) maintain the gate-off voltage (VGH) during the sampling period (t3). Accordingly, the first and second switch transistors T1 and T2 are turned on during the sampling period t3.

During the sampling period t3, the voltage of the gate terminal of the driving element DT, that is, the second node n2, increases due to the current flowing through the first and second switch transistors T1 and T2. When the driving element DT is turned off, the voltage Vn2 of the second node n2 is (Vdata-|Vth|). At this time, the voltage of the first node (n1) is also (Vdata-|Vth|). The voltage (Vgs) between the gate and source of the driving element (DT) in the sampling period (t3) is |Vgs|=Vdata-(Vdata-|Vth|)=|Vth|.

During the data writing period (t4), the nth scan signal (SCAN(n)) is inverted to the gate-off voltage (VGH). The (n-1)th scan signal (SCAN(n-1)) and the emission signal (EM(n)) maintain the gate-off voltage (VGH) during the data writing period (t4). Accordingly, all switch transistors (T1 to T6) remain in the off state during the data writing period (t4).

During the emission period (t5), the emission signal (EM(n)) continues to maintain the gate-on voltage (VGL) or is turned on/off at a predetermined duty ratio and swings between the gate-on voltage (VGL) and the gate-off voltage (VGH). can do. During the light emission period t5, the (n-1) and nth scan signals (SCAN(n-1), SCAN(n)) maintain the gate-off voltage (VGH). During the light emission period t5, the third and fourth switch transistors T3 and T4 may repeatedly turn on/off according to the voltage of the light emission signal EM. When the light emitting signal EM(n) is the gate-on voltage VGL, the third and fourth switch transistors T3 and T4 are turned on and current flows to the light emitting device OLED. At this time, the voltage (Vgs) between the gate and source of the driving device (DT) is |Vgs|=Vdd-(Vdata-|Vth|), and the current flowing in the light emitting device (OLED) is K(Vdd-Vdata) ² . K is a proportionality constant determined by the charge mobility of the driving element (DT), parasitic capacitance, and channel capacity.

The brightness of the light emitted by the light emitting device (OLED) is proportional to the current flowing in the light emitting device, and the pixel driving voltage (Vdd) supplied through the first power line 101 changes depending on the load or the pattern of the input image, but the input If the data voltage (Vdata) remains unchanged, the luminance emitted by the light emitting device (OLED) varies depending on the pixel driving voltage (Vdd) for the same data voltage (Vdata).

FIG. 7 illustrates an image processing method applied to the pixel structure of FIG. 2. The image processing method of FIG. 7 can be performed by a data conversion unit included in the timing controller 11.

As shown in FIG. 7, the image processing method may include inverse gamma compensation (DeGamma), four-color data generation (RGB to RGBW), three-color sub-pixel rendering including white (Sub-pixel Rendering), and gamma compensation.

The RGB three-color input data (Input Image) input in frame units is linearized through inverse gamma correction (DeGamma) so that the luminance changes linearly according to the gray level value.

Based on the inverse gamma-corrected RGB 3-color input data, 4-color data (RGBW) to be displayed in the 4-color subpixels that make up each unit pixel is generated (RGB to RGBW). Specifically, white data (W) is extracted from the three-color input data (RGB) for each unit pixel, and the three-color input data (RGB) of red, green, and blue are corrected according to the extracted white data (W), Four-color data (WRGB) of red, green, blue, and white can be generated.

For example, white data (W) may be set to a common grayscale value (or minimum grayscale value) among three color input data (RGB) of red, green, and blue (W'=min(R, G, B) In addition, each of the red, green, and blue data in the four-color data (WRGB) can be set to the grayscale value obtained by subtracting the white data (W) from each of the three-color input data (RGB) of red, green, and blue. There is (R'=(R-W'), G'=(G-W'), B'=(B-W')).

RGBW four-color data is converted into three-color data in which the three subpixels of RGW and BGW shown in FIG. 2 form one pixel. In Figure 2, since each pixel does not have an R or B subpixel, it must share the color it lacks with other neighboring pixels.

Since G and W subpixels are provided for each pixel, G and W data of RGBW four-color data can be used as is (G'(m, n)=G(m, n), W'( m, n)=W(m, n)).

Since one R and B subpixel is missing for every two pixels, the corresponding subpixel of a neighboring pixel must be shared, so the R and B data are divided into the data of the current pixel and the data of the previous pixel by applying a predetermined weight (Rw, Bw). Can be created using both.

Data (R'(m, n)) for the R subpixel belonging to the pixel in the m-th row and n-th column is the data (R R'(m, n) = Rw x R(m-1, n) + (1-Rw) x It can be obtained with R(m, n).

Additionally, similarly, the data (B'(m, n)) for the B subpixel belonging to the pixel in the mth row and nth column is the B subpixel belonging to the pixel in the (m-1)th row and nth column, which is the previous row. B'(m, n) = Bw It can be obtained as -Bw) x B(m, n).

The three-color data of RGW and BGW generated by sub-pixel rendering is non-linearized through gamma correction and provided to the data driving circuit 12 (Output Image).

FIG. 8 shows the results of improving information loss and color distortion occurring in the pixel structure of FIG. 2 according to the image processing method of FIG. 7. The left side is the same as the right figure of FIG. 3, and the right side is the image processing of FIG. 7. This is the output image of the image data generated by this method.

In the first and third pictures, the thin line pointing downward at a 45-degree angle is colored green or red differently from the surrounding colors in the picture on the left, but in the picture on the right, it is different from the color of the surrounding lines. It has the same color. Also, in the middle picture, the left picture does not display a thin blue line pointing downward at a 45-degree angle, but in the right picture, the blue thin line is displayed properly.

Therefore, the data of the subpixel, which exists only one in two pixels, is weighted and added to the data input to each of the two pixels, and the four-color data of RGBW is converted into three-color data of RGW and BGW, thereby increasing the transmittance of the transparent display device. While increasing, it is possible to solve problems that occur when displaying an image by converting it to three-color data including white, that is, the problem of the color of thin lines changing or disappearing lines.

FIG. 9 shows several size ratios of subpixels in the pixel structure of FIG. 5, and FIG. 10 shows the results of a recognition experiment on the subpixel size ratios of FIG. 9.

When implementing a transparent display in which a pixel is composed of three subpixels containing white as shown in Figure 2, in order to obtain the size ratio of the subpixels with optimal image quality, a simulation is performed by changing the relative size of the subpixels filling the light emitting area. and performed a viewer's perception test.

The size ratio of the subpixel, that is, the size ratio of the red (or blue) subpixel and the green (or white) subpixel, as shown in Figure 9, is 1:3.6, 1:1.6, 1:0.93, 1:0.6, 1:0.4, Nine different ratios were simulated, such as 1:0.27, 1:0.017, 1:0.1, and 1:0.04.

18 different simulated images were produced for each of the 9 subpixel size ratios, and the image quality of the simulated images was scored by 5 testers in a dark room with no light at 0 lux, based on pixels composed of an RGB stripe structure. Scores were scored using the Category Judgment method.

In the category judgment method, the score was divided into 9 points, where 1 is extremely bad, 2 is very bad, 3 is bad, 4 is slightly bad, and 5 is bad. is neither like or dislike, 6 is like slightly, 7 is like moderately, 8 is like very much, and 9 is like extremely. .

Looking at the evaluation results, as shown in FIG. 10, the size ratio of the red (or blue) subpixel and green (or white) subpixel of 1:0.4 obtained the highest score.

When the size ratio of the red (or blue) subpixel to the green (or white) subpixel is 1:3.6, the color appears greenish, and the size ratio of the red (or blue) subpixel to the green (or white) subpixel When the ratio was 1:0.93, there were many evaluations that the color was missing without any color characteristics, and when the size ratio of the red (or blue) subpixel to the green (or white) subpixel was 1:0.017, it was very yellowish (yellowish). , When the size ratio of the red (or blue) subpixel to the green (or white) subpixel was 1:0.04, a lot of red appeared (Reddish).

Therefore, in order to optimize the image quality of a transparent display device in which the light-emitting area of the pixel is composed of three subpixels containing white, the size of the red and blue subpixels in only one of the two neighboring pixels must be adjusted to that of both pixels. It is advantageous to make it 2.5 (=1/0.4) times larger than the size of the white or green subpixel.

Meanwhile, in Figure 2, the green subpixel and the white subpixel are arranged horizontally below the red subpixel (or blue subpixel) in the vertical direction, but there are three subpixels, that is, the red subpixel (or blue subpixel). , green subpixels and white subpixels may be arranged vertically side by side.

In Figure 2, the light-emitting area and the transmission area are arranged horizontally side by side in one pixel, but the light-emitting area and the transmission area may be arranged vertically side by side. In this case, the arrangement of the subpixels of the light-emitting area is similar to that of the light-emitting area in Figure 2. It can be rotated 90 degrees or 270 degrees.

In this case, the formula for rendering the data of the B and R subpixels in Figure 7 is R'(m, n) = Rw x R(m, n-1) + (1-Rw) x R(m, n) and B'(m, n) = Bw x B(m, n-1) + (1-Bw) x B(m, n).

Additionally, in FIG. 2, the transmissive area is disposed to the right of the light emitting area in both pixels of the first and second pixel lines, but the transmissive area may be disposed to the left of the light emitting area in the pixels of all pixel lines. In pixels of odd-numbered pixel lines, the transmission area is placed to the right of the light-emitting area, and in pixels of even-numbered pixel lines, the transmission area is placed to the left of the light-emitting area, so that the light-emitting area of the pixel and the transmission area are respectively the light-emitting area of the neighboring pixel. It may also be placed not adjacent to the hypertransmissive area.

Alternatively, the light-emitting area within the pixel can be divided into two and arranged diagonally, with the red subpixel (or blue subpixel) as the first light-emitting area and the green and white subpixels as the second light-emitting area, so that they are not adjacent to each other. When placed, the transmission area can be divided into two and placed not adjacent to each other.

To increase the transmittance of a transparent display device, the size ratio of the transparent area and the light-emitting area can be changed.

The transparent display device described in the specification can be described as follows.

A transparent display device according to an embodiment includes a display panel including a plurality of pixels including a transmissive area and a light-emitting area in which three subpixels including a white subpixel are disposed; a gate driving circuit that supplies a scan signal to a gate line connected to pixels of each horizontal line of the display panel; a data driving circuit that supplies data voltage to a plurality of pixels; And RGB input data consisting of three colors including red, green, and blue is converted into three-color data including white for each pixel and transmitted to the data driving circuit, and the two-color data are transmitted to neighboring pixels. It is characterized by including a timing controller that is calculated by weighting the data of the corresponding color.

In one embodiment, the plurality of pixels include a first pixel including red, green, and white subpixels and a second pixel including blue, green, and white subpixels, and the two colors may be red and blue. .

In one embodiment, the timing controller converts RGB input data to RGBW data consisting of four colors including red, green, blue, and white, and converts the RGBW data to include red, green, and white for the first pixel. RGW data for the first pixel and BGW data including blue, green, and white for the second pixel.

In one embodiment, the size ratio of the red subpixel and the green or white subpixel in the first pixel may be 1:0.4, and the size ratio of the blue subpixel and the green or white subpixel in the second pixel may be 1:0.4. .

In one embodiment, the light-emitting area and the transmission area of the pixel may be arranged side by side in the horizontal direction, and the light-emitting area of the first pixel and the light-emitting area of the second pixel may be adjacent to each other in the vertical direction.

In one embodiment, in the light-emitting area of the first pixel, the green subpixel and the white subpixel are arranged side by side in the horizontal direction, the red subpixel and the green or white subpixel are arranged side by side in the vertical direction, and the light emission of the second pixel In the area, green subpixels and white subpixels may be arranged side by side in the horizontal direction, and blue subpixels and green or white subpixels may be arranged side by side in the vertical direction.

In one embodiment, the light-emitting area and the transmission area of the pixel may be arranged vertically side by side, and the light-emitting area of the first pixel and the light-emitting area of the second pixel may be adjacent to each other in the horizontal direction.

In one embodiment, in the emission area of the first pixel, the green subpixel and the white subpixel are arranged vertically side by side, the red subpixel and the green or white subpixel are arranged horizontally, and the second pixel emits light. In the area, a green subpixel and a white subpixel may be arranged side by side in the vertical direction, and a blue subpixel and a green or white subpixel may be arranged side by side in the horizontal direction.

In one embodiment, the light-emitting area and the transmission area of the pixel may be arranged side by side in the horizontal direction, and the light-emitting area of the first pixel and the transmission area of the second pixel may be adjacent to each other in the vertical direction.

In one embodiment, in the first pixel, the light emitting area is separated into a 1-1 light emitting area of the red subpixel and a 1-2 light emitting area of the green and white subpixels, and the 1-1 light emitting area and the 1-2 light emitting area of the green and white subpixels. 2 The light-emitting areas are arranged non-adjacently, and the transmission area is also divided into a 1-1 transmission area and a 1-2 transmission area and are arranged not adjacent to each other, and in the second pixel, the light-emitting area is in the 2-1st transmission area of the blue subpixel. It is separated into a 1 emission area and a 2-2 emission area of green and white subpixels, the 2-1 emission area and the 2-2 emission area are disposed not adjacent to each other, and the transmission area is also divided into the 2-1 transmission area and the 2-2 emission area. It may be divided into 2-2 transmission areas and placed not adjacent to each other.

A method of processing image data in a transparent display device according to another embodiment includes displaying image data on a transparent display device including a plurality of pixels including a transmissive region and a light-emitting region where a plurality of subpixels including a white subpixel are disposed. A first step of processing image data and converting RGB input data consisting of three colors including red, green, and blue into RGBW data consisting of four colors including red, green, blue, and white; RGBW data, RGW data including red, green, and white for a first pixel including red, green, and white subpixels, and blue, green, and white for a second pixel including blue, green, and white subpixels. A second step of converting to BGW data including, converting the red and blue color data by weighting them with the corresponding color data of neighboring pixels; And a third step of supplying and displaying RGW data and BGW data to the first pixel and the second pixel, respectively.

In one embodiment, the second step may maintain the green and white color data for the first and second pixels as the corresponding color data in the RGBW data.

In one embodiment, a method of processing image data in a transparent display device includes, prior to the first step, linearizing RGB input data by performing inverse gamma compensation; And between the second and third steps, the step of non-linearizing the RGW data and BGW data by gamma correction may be further included.

In one embodiment, the first step is to convert W data from RGBW data to a common grayscale value of RGB input data, and subtract R data, G data, and B data from RGBW data to the converted W data from RGB input data, respectively. You can get it by doing this.

Through the above-described content, those skilled in the art will be able to see that various changes and modifications can be made without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be defined by the scope of the patent claims.

10: Display panel 11: Timing controller
12: data driving circuit 13: gate driving circuit
14: data line 15: gate line
16: power unit

Claims (14)

A display panel including a plurality of pixels including a transparent area and a light-emitting area in which three subpixels including a white subpixel are disposed;
a gate driving circuit that supplies a scan signal to a gate line connected to pixels of each horizontal line of the display panel;
a data driving circuit that supplies data voltage to the plurality of pixels; and
RGB input data consisting of three colors including red, green, and blue is converted into three-color data including white for each pixel and transmitted to the data driving circuit, and the two-color data are transmitted to neighboring pixels. It is configured to include a timing controller, which is calculated by weighting the data of the corresponding color,
The plurality of pixels include a first pixel including red, green, and white subpixels, and a second pixel including blue, green, and white subpixels, and the two colors are red and blue,
The timing controller converts the RGB input data into RGBW data consisting of four colors including red, green, blue, and white, and converts the RGBW data into the red, green, and white for the first pixel. Converting RGW data containing and BGW data containing the blue, green and white for the second pixel,
Converting the RGB input data of the timing controller into RGBW data consisting of four colors including red, green, blue, and white,
Converting W data among the RGBW data to a common grayscale value of the RGB input data, obtaining R data, G data, and B data among the RGBW data by subtracting the converted W data from the RGB input data, respectively,
In the process of converting the RGBW data into RGW data including the red, green, and white for the first pixel and BGW data including the blue, green, and white for the second pixel,
The data of the red subpixel is obtained as a weighted sum of the data of the red subpixel in the previous row and the same column and the data of the red subpixel in the next row and the same column,
A method of processing image data in a transparent display device, wherein the blue subpixel data is obtained as a weighted sum of the blue subpixel data of the previous row and the same column and the blue subpixel data of the next row and the same column. delete delete According to claim 1,
The size ratio of the red subpixel and the green or white subpixel in the first pixel is 1:0.4, and the size ratio of the blue subpixel and the green or white subpixel in the second pixel is 1:0.4. Characterized by a transparent display device. According to claim 1,
In the pixel, the light-emitting area and the transmission area are arranged side by side in the horizontal direction, and the light-emitting area of the first pixel and the light-emitting area of the second pixel are adjacent to each other in the vertical direction. According to clause 5,
In the light emitting area of the first pixel, the green subpixel and the white subpixel are arranged side by side in the horizontal direction, and the red subpixel and the green or white subpixel are arranged side by side in the vertical direction,
In the light emitting area of the second pixel, the green subpixel and the white subpixel are arranged side by side in the horizontal direction, and the blue subpixel and the green or white subpixel are arranged side by side in the vertical direction. Transparent display device. According to claim 1,
In the pixel, the light-emitting area and the transmission area are arranged vertically side by side, and the light-emitting area of the first pixel and the light-emitting area of the second pixel are adjacent to each other in the horizontal direction. According to clause 7,
In the light emitting area of the first pixel, the green subpixel and the white subpixel are arranged side by side in the vertical direction, and the red subpixel and the green or white subpixel are arranged side by side in the horizontal direction,
In the light emitting area of the second pixel, the green subpixel and the white subpixel are arranged side by side in the vertical direction, and the blue subpixel and the green or white subpixel are arranged side by side in the horizontal direction. Transparent display device. According to claim 1,
A transparent display device, wherein the light emitting area and the transmission area of the pixel are arranged side by side in the horizontal direction, and the light emitting area of the first pixel and the transmission area of the second pixel are adjacent to each other in the vertical direction. According to claim 1,
In the first pixel, the light emitting area is divided into a 1-1 light emitting area of the red subpixel and a 1-2 light emitting area of the green and white subpixels, and the 1-1 light emitting area and the 1-2 light emitting area of the green and white subpixels. Two light-emitting areas are arranged not adjacent to each other, and the transmission area is also divided into the 1-1 transmission area and the 1-2 transmission area and are arranged not adjacent to each other,
In the second pixel, the light-emitting area is divided into a 2-1 light-emitting area of the blue subpixel and a 2-2 light-emitting area of the green and white subpixels, and the 2-1 light-emitting area and the 2- A transparent display device, wherein two light-emitting areas are arranged not adjacent to each other, and the transmission area is divided into the 2-1st transmission area and the 2-2 transmission area and are arranged not adjacent to each other. A method of processing image data to be displayed on a transparent display device including a plurality of pixels including a transmissive region and a light-emitting region in which a plurality of subpixels including a white subpixel are disposed, comprising:
A first step of converting RGB input data consisting of three colors including red, green, and blue into RGBW data consisting of four colors including red, green, blue, and white;
The RGBW data includes the RGW data including red, green, and white for a first pixel including red, green, and white subpixels, and the blue for a second pixel including blue, green, and white subpixels, A second step of converting the red and blue color data into BGW data including green and white by weighting the red and blue color data with the corresponding color data of neighboring pixels; and
A third step of supplying and displaying the RGW data and the BGW data to the first pixel and the second pixel, respectively,
In the first step, W data among the RGBW data is converted to a common grayscale value of the RGB input data, and R data, G data, and B data among the RGBW data are converted into the converted W data from the RGB input data, respectively. Get it by subtracting it,
In the second step,
The data of the red subpixel is obtained as a weighted sum of the data of the red subpixel in the previous row and the same column and the data of the red subpixel in the next row and the same column,
A method of processing image data in a transparent display device, wherein the blue subpixel data is obtained as a weighted sum of the blue subpixel data of the previous row and the same column and the blue subpixel data of the next row and the same column. According to claim 11,
In the second step, the green and white color data for the first and second pixels are maintained as the corresponding color data in the RGBW data. According to claim 11,
Prior to the first step, linearizing the RGB input data by performing inverse gamma compensation; and
Between the second step and the third step, a method of processing image data in a transparent display device, further comprising the step of non-linearizing the RGW data and BGW data by performing gamma correction.

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