KR20170075173A - Transparent display device and method for driving the same - Google Patents

Abstract

The present invention relates to a transparent display device and a method of driving the same, which can provide an optimal perceived image quality to a user by adjusting the transmittance in consideration of image characteristics and user distance. According to an embodiment of the present invention, a method of driving a transparent display device converts three-color data of an input image into four-color data and analyzes four-color data of the input image to determine whether the image is a pure-color image. When it is judged to be a pure-color image, the transmission area and the non-transmission area are detected from the four-color data of the input image. A distance sensor is used to sense the distance between users from the transparent display device. Adjusts the luminance of the four-color data in the transmission region according to the sensed distance information, and outputs the four-color data with the luminance adjusted.

Description

TECHNICAL FIELD [0001] The present invention relates to a transparent display device and a method of driving the same.

The present invention relates to a transparent display device and a method of driving the same, which can provide an optimal perceived image quality to a user by adjusting the transmittance in consideration of image characteristics and user distance.

BACKGROUND ART In recent years, a transparent display device using a liquid crystal display (LCD) device or an organic light emitting diode (OLED) display device has been developed as a display device.

Since the transparent display device transmits light in both forward and backward directions, information can be displayed in both directions of the display device, and each user facing the display device can see beyond the transparent display device.

Transparent display devices can be applied to various applications such as automobile glass, building glass, advertisement display board, cooler door, screen door, and the like.

Referring to FIG. 1, a transparent display device uses R, G, B, and W (white) subpixel structures having a high transmittance in contrast to R (Red), G (Green), and B (Blue) subpixel structures. However, in the RGBW subpixel structure, the number of RGB subpixels representing the color at the same resolution is relatively reduced, resulting in a problem of a decline in the luminance of pure color.

Therefore, in a transparent display device using four-color subpixels, a luminance compensation method of reducing the transmittance of a background portion when a high-pureness image is input is considered. However, if the transmittance of the background portion is reduced, There is a problem of deterioration.

The present invention provides a transparent display device and a method of driving the same that can provide an optimal perceived image quality to a user by adjusting transmittance in consideration of image characteristics and user distance.

A transparent display device according to an embodiment of the present invention includes a transparent display unit for displaying image data, a distance sensor mounted on the transparent display device for sensing a distance of the user, a display driver for supplying the image data and driving the transparent display unit, , And an image processing circuit.

The image processing circuit analyzes the input image to analyze the input image to detect the transmission area and the non-transmission area, and adjusts the luminance of the image data of the transmission area according to the sensed distance information from the distance sensor to output do.

The image processing circuit converts the three-color data of the input image into four-color data before analyzing the input image.

The image processing circuit converts the W data among the four-color data of the non-transmissive area into the luminance emphasis data (maximum value) and outputs it.

A method of driving a transparent display device according to an embodiment of the present invention converts three-color data of an input image into four-color data and analyzes four-color data of the input image to determine whether the image is a pure-color image. When it is judged to be a pure-color image, the four-color data of the input image is analyzed to detect the transmissive area and the non-transmissive area. A distance sensor is used to sense the distance between users from the transparent display device. Adjusts the luminance of the four-color data in the transmission region according to the sensed distance information, and outputs the four-color data with the luminance adjusted.

 (Gain function) for adjusting the luminance according to the sensed distance information, and compensates the four-color data of the transmission region using the selected gain value (gain function). The closer the sensed distance information is, the more the degree of luminance compensation of the four-color data in the transmissive area using the gain value (gain function) is reduced.

A transparent display device and a driving method thereof according to an embodiment of the present invention analyze an input image to adjust luminance of a transmission region according to a distance of a user when it is determined that the image has high color purities, By emphasizing the luminance, the degree of luminance compensation (reduction of transmittance) of the transmissive region (background portion) is reduced when the user distance is close to improve the transmissivity with respect to the prior art and the perceptual transparency through the non-transmissive region is improved, It is possible to provide a desired image quality.

FIG. 1 is a view showing a contrast of a three-color subpixel and a four-color subpixel structure applied to a transparent display device.
FIG. 2 is a diagram for explaining a method of compensating background luminance for a pure-color image in a transparent display device according to the prior art of the present invention.
FIG. 3 is a photograph showing a result of compensation of a background luminance of a pure-color image of a transparent display device according to the prior art of the present invention.
4 is a block diagram schematically showing a configuration of a transparent display device according to an embodiment of the present invention.
5A and 5B are equivalent circuit diagrams illustrating a configuration of a subpixel according to an embodiment of the present invention.
6 is a block diagram showing a configuration of an image processing circuit of a transparent display device according to an embodiment of the present invention.
7 is a graph for explaining a background luminance compensation method for a pure color image of a transparent display device according to an embodiment of the present invention.
FIG. 8 is a diagram illustrating results of W sub-pixel emphasis in a non-transmissive region in a transparent display device according to an embodiment of the present invention.
9 is a photograph showing a comparison result of background luminance compensation according to sensing distance of a transparent display device according to an embodiment of the present invention.

Prior to the description of the embodiments of the present invention, the phenomenon of perceived degradation of the transparent display device according to the prior art of the present invention will be described first.

FIG. 2 is a view for explaining a method of compensating a background luminance for a pure-color image in a transparent display device according to the prior art of the present invention, FIG. 3 is a diagram for explaining a background luminance This is a picture showing the compensation result of

The transparent display device according to the prior art has four color subpixels and has a high transmittance with respect to the three color subpixels. However, due to the disadvantage that the luminance of the pure color is low, When a pure-color image is input, a technique of increasing the perceived luminance of the pure-color image is applied by applying a luminance compensation method for reducing the transmittance of the background luminance displaying white, that is, the luminance.

However, the transparent display device according to the prior art has a problem that the object recognition level on the back of the transparent display device is lowered by lowering the transmittance of the background portion to about 75% in an input image with high color purities.

For example, as shown in FIG. 3 (a), when the luminance compensation technique for reducing the transmittance is applied in comparison with the case where the luminance compensation for reducing the transmittance of the background portion is not applied, As can be seen, the recognition level of the back surface is reduced.

Although the transparent display device requires a high transmittance so that the backside object can be seen clearly, the prior art can not consider the use environment of the user's transparent display device by adjusting the transmittance only considering the characteristics of the input image.

Since most users are close to the transparent display device when the user wants to recognize an object on the back side of the transparent display device (inside the transparent refrigerator) through the transparent display device applied to the transparent refrigerator or the like, Transparent display devices are designed to provide users with optimum perceived image quality by adjusting transmittance in consideration of image characteristics and user distance.

Hereinafter, a transparent display device and a driving method thereof according to a preferred embodiment of the present invention will be described.

FIG. 4 is a block diagram schematically illustrating a configuration of a transparent display device according to an embodiment of the present invention, and FIGS. 5A and 5B are equivalent circuit diagrams illustrating the configurations of subpixels according to an embodiment of the present invention.

4, a transparent display device according to an exemplary embodiment of the present invention includes an image processing circuit 100, a timing controller 150, a data driver 200 and a gate driver 300, a transparent display 400, A voltage generator 500, a distance sensor 600, and the like. Here, the timing controller 150, the data driver 200, and the gate driver 300 may be represented as a display driver for driving the transparent display unit 400.

The transparent display unit 400 displays an image through a pixel array in which pixels are arranged in a matrix form. Each pixel of the pixel array is composed of R (Red), G (Green), B (Blue) and W (White) subpixels. The transparent display unit 400 displays an image through a pixel array in which pixels are arranged in a matrix form. As the transparent display unit 400, a liquid crystal display (LCD) panel, an organic light emitting diode (OLED) display panel, or the like can be used.

5A, each sub-pixel SP includes a thin film transistor (TFT), a thin film transistor (TFT) connected to a gate line GL and a data line DL, And a liquid crystal capacitor Clc and a storage capacitor Cst connected in parallel between the common electrode and the common electrode. The liquid crystal capacitor Clc charges the difference voltage between the data signal supplied to the pixel electrode through the thin film transistor TFT and the common voltage Vcom supplied to the common electrode, drives the liquid crystal according to the charged voltage, . The storage capacitor Cst stably maintains the voltage charged in the liquid crystal capacitor Clc

5B, each subpixel SP is connected between a high potential power supply line (EVDD) line and a low potential power supply line (EVSS) line, as shown in FIG. 5 (b) And a pixel circuit including a first and a second switching TFT (ST1, ST2), a driving TFT (DT) and a storage capacitor (Cst) for independently driving the OLED element, It is not limited to the structure of FIG.

The OLED element includes an anode connected to the driving TFT DT, a cathode connected to the low potential voltage EVSS, and a light emitting layer between the anode and the cathode to emit light proportional to the amount of current supplied from the driving TFT DT Occurs.

The first switching TFT ST1 is driven by the gate signal of one gate line GLa to supply the data voltage from the corresponding data line DL to the gate node of the driving TFT DT and the second switching TFT ST2 Is driven by the gate signal of the other gate line GLb to supply a reference voltage from the reference line REF to the source node of the driving TFT DT. The second switching TFT ST2 is further used as a path for outputting the current from the driving TFT DT to the reference line REF in the sensing mode.

The storage capacitor Cst connected between the gate node and the source node of the driving TFT DT is connected between the data voltage supplied to the gate node through the first switching TFT ST1 and the data voltage supplied to the source node through the second switching TFT ST2. And supplies the difference voltage to the driving voltage of the driving TFT DT.

The driving TFT DT controls the current supplied from the high potential power supply EVDD according to the driving voltage supplied from the storage capacitor Cst to supply a current proportional to the driving voltage to the OLED element to emit the OLED element.

The data driver 200 receives data control signals and video data from the timing controller 150. The data driver 200 is driven in accordance with the data control signal to divide the set of reference gamma voltages supplied from the gamma voltage generator 500 into the gray voltages corresponding to the gray levels of the data, Converts the digital image data into analog data signals, and supplies the analog data signals to the data lines of the transparent display unit 400, respectively.

The data driver 200 includes a plurality of data driver ICs for dividing and driving the data lines of the transparent display unit 400. Each data driver IC includes a tape carrier package (TCP), a chip on film (COF) Circuit or the like and mounted on the transparent display unit 400 by a tape automatic bonding (TAB) method or on a transparent display unit 400 by a COG (Chip On Glass) method.

The gate driver 300 drives the plurality of gate lines of the transparent display unit 400 using the gate control signal GCS supplied from the timing controller 150. The gate driver 300 supplies the gate-on voltage to the respective gate lines in response to the gate control signals, and supplies the gate-off voltages during the remaining periods. The gate driving unit 300 receives the gate control signal GCS from the timing controller 150 or receives the gate control signal GCS from the timing controller 150 via the data driving unit 200, Via a power supply circuit (not shown).

The gate driver 300 includes at least one gate IC and is mounted on a circuit film such as TCP, COF, FPC or the like to be attached to the transparent display unit 400 in a TAB manner or mounted on a transparent display unit 400 in a COG manner . Alternatively, the gate driver 300 may be formed on the thin film transistor substrate together with the thin film transistor array constituting the pixel array of the transparent display unit 400, thereby forming a GIP (Gate In Panel) type As shown in FIG.

The distance sensor 600 senses the distance between the transparent display unit 400 and the user (viewer) using a conventional distance sensor and outputs the sensed distance information to the image processing circuit 100.

The image processing circuit 100 converts the three-color data (R, G, B) of the input image into four-color data (R, G, B, W) using a normal RGB-to-WRGB conversion method. The image processing circuit 100 analyzes the image converted into the four-color data to determine whether the input image is a pure color image. The pure-color image can be defined as a case where any one of RGB of the four-color data has a white gradation value of a specific high gradation or higher and the remaining two-color data has a black gradation value of a number of pixels of the same color.

The image processing circuit 100 detects four color data of the transmission area and four color data of the non-transmission area from the input image through the image analysis, if the input image is determined as a pure color image through image analysis. The non-transmissive region is an area for displaying an image. Most of the transmissive region is a background portion, and the input image can be classified into data of the transmissive region and data of the non-transmissive region through image analysis. The image processing circuit 100 adjusts the luminance of the four-color data of the transmission region using different gain values according to the distance information sensed from the distance sensor 600, thereby adjusting the luminance of the transmission region, And the transmittance is adjusted by varying the degree. The image processing circuit 100 can improve the transparency of the non-transmissive area by converting only the W data among the four-color data in the non-transmissive area into the maximum tone value. A detailed description thereof will be given later.

In addition, the image processing circuit 100 may further perform necessary image processing such as power consumption reduction, image quality compensation, degradation compensation, and the like, and output the image-processed four-color data to the tamimi controller 150. The image processing circuit 100 supplies the image data and the timing control signals to the timing controller 150.

Meanwhile, the image processing circuit 100 may be incorporated in the timing controller 150, and the image processing circuit 100 and the timing controller 150 may be integrated into one IC.

The timing controller 150 receives timing control signals and image data from the image processing circuit 100.

The timing controller 150 generates a data control signal DCS and a gate control signal GCS using the timing control signals input from the image processing circuit 100 and supplies the data control signal DCS and the gate control signal GCS to the data driver 200 and the gate driver 300, Output. The timing control signals include a dot clock, a data enable signal, a vertical synchronizing signal, and a horizontal synchronizing signal. The vertical synchronizing signal and the horizontal synchronizing signal can be omitted because they can be generated by counting the data enabling signal. The data control signals may include a source start pulse for controlling driving of the data driver 200, a source sampling clock, a source output enable signal, and the like. The gate control signals may include gate start pulses, gate shift clocks, and the like, which control the driving of the gate driver 300.

The timing controller 150 controls the driving characteristics of each subpixel (threshold voltage, mobility, OLED threshold voltage, etc.) of the transparent display unit 400 to a deviation of the image data supplied from the image processing circuit 100, Such as external compensation or deterioration compensation, for sensing and compensating the image data through the image sensor 200, and then outputting the image data to the data driver 200.

FIG. 6 is a block diagram illustrating a configuration of an image processing circuit of a transparent display device according to an embodiment of the present invention. FIG. 7 illustrates a background luminance compensation method for a pure color image of a transparent display device according to an embodiment of the present invention FIG.

6, the image processing circuit 100 includes a four-color conversion unit 110, a frame memory 120, a pure color image determination unit 130, a transmission region detection unit 140, a luminance control unit 150, a W An emphasis unit 160, a distance determination unit 170, and the like.

The four-color conversion unit 110 converts the three-color data Ri, Gi, and Bi into the four-color data R, W, G, and B using a normal RGB-to- And outputs the same to the decolorizing image determining unit 130. [0050] For example, the four-color conversion unit 110 sets the minimum value among the input three-color data Ri, Gi and Bi as W data and subtracts W data from each of the three-color data Ri, And can be converted into color data (R, W, G, B). Meanwhile, the RGB-to-WRGB conversion method in the four-color conversion unit 110 is not limited to the above-described method, and any one of various known RGB-to-WRGB conversion methods may be used.

The frame memory 120 stores the four-color data (R, W, G, B) from the four-color conversion unit 110 on a frame-by-frame basis. The data R, W, G and B stored in the frame memory 120 are adjusted by the luminance controller 150 according to the sensed distance information of the luminance of the transmissive area, Or the W data in the non-transmissive area is converted into luminance emphasis data and updated by the W emphasis unit 160. [ Accordingly, the data (Ro, Wo, Go, Bo) output from the frame memory 120 includes data selectively corrected according to the image characteristics and the distance of the sensed user.

The colorimetric image determination unit 130 analyzes the four color data R, G, B, and W supplied from the four-color conversion unit 110 to determine whether the input image is a pure color image. The decoloring image determination unit 130 determines whether any one of the three-color data (R, G, B) that is color data in the four-color data (R, G, B, W) has a white tone value that is a specific high tone, The remaining two-color data is a pixel having a black gradation value (0) as a pure-color pixel, counts the number of pure-color pixels, judges an input image as a pure-color image if the number is more than a predetermined reference value, And outputs the decoded image determination signal to the transmission area detection unit 140. [

On the other hand, the decolorizing image determiner 130 determines whether or not the tincture data (Ri, Gi, Bi) is used in place of the four-color data R, G, B and W for the input image from the four- It is possible to determine whether the input image is a pure color image in the same way.

The transmissive area detecting unit 140 reads and analyzes four-color data (R, G, B, and W) in units of frames from the frame memory 120 when the purple color image determination signal is input from the purple color image determination unit 130, Data of the transmissive area, and data of the non-transmissive area, respectively. The transmissive area detecting unit 140 determines that the gray level of each of the four color data (R, W, G, and B) is the data of the transmissive area if all of the gray levels are higher than a specified high gray level, As shown in FIG. The non-transmissive region is an area for displaying an image, and the transmissive region is partially included in a non-transmissive region, but most of the background region corresponds to a visible portion of a backside object of the transparent display device. In addition, the transmissive area detecting unit 140 can divide the four-color data (R, W, G, B) of the frame memory 120 into a transmissive area and a non-transmissive area using another conventional image analysis method. The transmissive area detection unit 140 may not perform the operation of detecting the transmissive area and the non-transmissive area described above unless a purple color image determination signal is input from the purple color image determination unit 130.

The transmissive area detection unit 140 divides the four color data (R, W, G, B) of the frame memory 120 into a transmissive area and a non-transmissive area and transmits address information on the transmissive area data to the luminance controller 150 And supplies address information on the non-transmitting area data to the W emphasis unit 160. [

The distance determining unit 170 determines a distance mode preset by the designer using the distance information from the distance sensor 600 to the user and outputs a control signal indicating the determined distance to the brightness adjusting unit 150 and the W And outputs it to the emphasis unit 160. For example, the distance determination unit 170 may output the first to third control signals according to the distance order of the sensed distance information.

The luminance controller 150 reads the four color data R, G, B, and W of the transmission area from the frame memory 120 using the address information of the transmission area supplied from the transmission area detector 140, G, B, and W) of the transmissive area according to a control signal according to the distance from the user determined by the determination unit 170.

The luminance controller 150 selects one of the gain values (gain function) according to the control signal indicating the distance information among the different gain values determined in advance and selects the gain value (gain function) The luminance compensation operation for reducing the luminance of the four-color data (R, G, B, W) is performed.

For example, as shown in FIG. 7, the luminance of the transmissive region corresponding to the background portion in the section where the input image is determined to be pure color is compensated to decrease at different compensation rates according to the distance information.

The luminance controller 150 uses a first gain value (gain function) G1 having the smallest gray scale value versus luminance decreasing rate of the image data when the distance information to the user is closest and uses the first gray level value (Gain function) G3 that is the largest gain value (gain function) G2 that is the medium gain and the third gain value (gain function) G3 that is the medium gain gain The data R, G, B and W are corrected and the frame memory 120 is updated with the four color data R, G, B and W of the corrected transmission area. Since the first to third gain values G1, G2 and G3 are for reducing the luminance, they have a value larger than 0 and smaller than 1. 7, each of the first to third gain values G1, G2, and G3 may be a non-linear function that increases as the gray level value of a specific high gray level increases.

W enhancement unit 160 uses the address information of the non-transmissive area supplied from the transmissive area detection unit 140 to adjust the brightness of the four-color data (R, G, B, W, and converts the W data of the non-transmissive area into luminance emphasis data according to the control signal according to the distance from the user determined by the distance determination unit 170 to update the frame memory 120. [

W emphasis unit 160 may not convert or convert W data of the non-transmissive area into luminance emphasis data, that is, maximum value data, in response to a control signal indicating distance information to the user determined by distance determining unit 170 .

W emphasis unit 160 converts the W data of the non-transmissive area into the maximum value data and updates the frame memory 120 when the distance information to the user is close. W emphasis unit 160 may not convert the W data of the non-transmissive area into the maximum value data and correct it when the distance information to the user is far.

FIG. 8 is a diagram illustrating results of W sub-pixel emphasis in a non-transmissive region in a transparent display device according to an embodiment of the present invention.

Referring to FIG. 8, when the R sub-pixels of the non-transmissive region display red color, there is a disadvantage in that the color recognized by the user is lowered as shown in (a), but as shown in (b) When the data of the pixel is converted into the maximum value and displayed, the transparency is improved in the non-transmissive region, and thus the perceived image quality is improved.

9 is a photograph showing a comparison result of background luminance compensation according to sensing distance of a transparent display device according to an embodiment of the present invention.

Referring to FIG. 9A, when the transparent display device displays a pure-color image and the distance from the user is long (prior art), the degree of decrease in the luminance of the transmission region corresponding to the background portion is large, Thus, the degree of recognition of the back surface object is low.

Referring to FIG. 9 (b), in the present invention, when the distance from the user is small and the distance from the user is small, the degree of decrease in the luminance of the transmission region corresponding to the background portion is reduced, And the transparency is enhanced due to the emphasis of the W data in the non-transmissive area. Thus, it can be seen that the perceived image quality is improved.

As described above, the transparent display device and the driving method thereof according to an embodiment of the present invention analyze the input image to adjust the luminance of the transmissive area according to the distance of the user when it is determined that the image has high color purities, The brightness of the W subpixel is emphasized, so that the degree of brightness compensation (reduction of transmittance) of the transmissive area (background part) is reduced when the user distance is close to improve the transmissivity of the prior art and the perceptual transparency of the non- It is possible to provide an optimal perceived image quality to the user.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Therefore, the technical scope of the present invention should not be limited to the contents described in the detailed description of the specification, but should be defined by the claims.

100: Image processing circuit SP: Sub-pixel
150: timing controller 200: data driver
300: gate driver 400: transparent display part
500: gamma voltage generator 600: distance sensor
110: four-color conversion unit 120: frame memory
130: purple image determining unit 140: transmissive area detecting unit
150: brightness adjusting section 160: W-emphasis section
170:

Claims (8)

A transparent display section for displaying image data,
A distance sensor mounted on the transparent display device and sensing a distance of the user;
A display driver for supplying the image data and driving the transparent display unit,
And an image processing circuit for processing the input image and supplying the image data to the display driver,
The image processing circuit
The input image is analyzed to determine a pure color image. The input image is analyzed to detect a transmissive area and a non-transmissive area. The brightness of image data of the transmissive area is adjusted according to the sensed distance information from the distance sensor, . The method according to claim 1,
The image processing circuit
Converting the three-color data of the input image into four-color data before analyzing the input image,
And converting the W data among the four-color data in the non-transmissive area into luminance emphasis data and outputting the W data. The method of claim 2,
The image processing circuit
Selecting one of a plurality of gain functions for adjusting the luminance according to the sensed distance information, compensating and outputting the four-color data of the transmissive area using the selected gain function,
And the degree of luminance compensation of the four-color data of the transmissive area using the gain function decreases as the sensed distance information approaches. The method of claim 3,
The image processing circuit
Correcting the four-color data of the transmissive area so that the luminance decreases using the selected gain function,
And converts the W data of the non-transmissive area into a maximum value and outputs the converted maximum value. The method according to claim 1,
The image processing circuit
And determines the input image as the pure-color image when the number of data of the four-color data of the input image is equal to or greater than a reference value. Converting the three-color data of the input image into four-color data,
Analyzing the four-color data of the input image to determine whether it is a pure-color image;
Analyzing the four-color data of the input image to detect a transmission area and a non-transmission area when it is judged to be the pure-color image;
Sensing a distance between the user and the transparent display device using the distance sensor,
And controlling the brightness of the four-color data in the transmissive area according to the sensed distance information, and outputting the four-color data with the brightness adjusted. The method of claim 6,
Converting the W data among the four-color data in the non-transmissive area to a maximum value and outputting the converted maximum value. The method of claim 6,
The step of adjusting the luminance of the four-color data of the transmissive area
Selecting one of a plurality of gain values for adjusting the luminance according to the sensed distance information and compensating the four-color data of the transmissive area using the selected gain value,
And the degree of luminance compensation of the four-color data of the transmissive area using the gain value is reduced as the sensed distance information is closer to the sensed distance information.

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