KR102633405B1 - Display device - Google Patents

Abstract

The display device includes: a display panel for displaying an image having a plurality of pixels connected to a gate line and a data line; a driving circuit for supplying data voltages to a plurality of pixels by driving a gate line and a data line; and a timing controller for selecting a first area from the input image data, adjusting the luminance of the first area and the thickness of the line included in the first area based on the illuminance value, and transmitting the information to the driving circuit. You can.

Description

Display device {DISPLAY DEVICE}

This specification relates to a display device, and more specifically, to a method of processing images to increase visibility of content in a vehicle display device.

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, plastic substrate OLED displays are being adopted as automotive displays because they facilitate design and can express black colors well to provide high-quality display. However, if the luminance is low, the driver's ability to quickly recognize the content displayed on the display decreases, and the decrease in content visibility is maximized especially in low-illuminance situations. Additionally, if the brightness of the entire display is excessively increased, afterimages may occur and power consumption may increase.

Embodiments disclosed in this specification take this situation into consideration, and the purpose of this specification is to provide an image processing method that increases visibility of content displayed on a display device.

A display device according to an embodiment includes a display panel for displaying an image having a plurality of pixels connected to a gate line and a data line; a driving circuit for supplying data voltages to a plurality of pixels by driving a gate line and a data line; and a timing controller for selecting a first area from the input image data, adjusting the luminance of the first area and the thickness of the line included in the first area based on the illuminance value, and transmitting the information to the driving circuit. It is characterized by

An image processing method in a display device according to another embodiment includes selecting a first area from input image data; increasing the luminance of the first area based on the illuminance value; adjusting the thickness of a line included in the first area based on the illuminance value; and displaying image data in the first area through image processing.

By applying an algorithm that improves image quality only partially, rather than to the entire display device, it is possible to increase the visibility of the area where the driver's gaze stays while minimizing the increase in power consumption and afterimage problems that occur when increasing the brightness of the display device. .

Additionally, by adjusting the thickness of the line according to the illuminance, the driver can more accurately recognize the text compared to the method of simply increasing the luminance.

1 shows an organic light emitting display device made of a plastic substrate applied to a vehicle dashboard;
Figure 2 shows an embodiment of processing the image of the area where the driver's gaze remains to increase visibility,
Figure 3 shows the display device as functional blocks;
4 shows an example of a pixel circuit;
Figure 5 shows signals related to driving in the pixel circuit of Figure 4;
Figure 6 shows an operation flowchart of an image processing method to increase visibility of the boosting area where the driver's gaze stays.
Figure 7a shows human cognitive ability according to viewing angle,
Figure 7b shows an example of determining the size of the boosting area to be image processed according to the distance from the eye.
Figure 8a is a graph showing the appropriate display luminance level according to illuminance,
Figure 8b shows an example of upwardly adjusting the luminance of the boosting area where the driver's gaze stays.
Figure 9 shows an operation flowchart for a method of adjusting the thickness of the line in the boosting area according to the illuminance to increase visibility;
Figure 10 compares the results of processing the boundaries of the boosting area,
Figures 11A to 11C illustrate the process of generating a lookup table to be referenced when determining the thickness of a line for each illuminance;
Figure 12a graphically shows the relationship between line thickness and contrast sensitivity;
Figure 12b shows the process of determining the line thickness with reference to the look-up table created in the process of Figure 11,
Figure 13 shows the results of image processing of the area where the driver's gaze remains at night according to the operation flowchart of Figure 6.

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 shows an organic light emitting display device made of a plastic substrate applied to the dashboard of a vehicle. In the interior of the vehicle shown in Figure 1, there is an instrument panel that displays driving information for the driver's seat and a display device in the center of the dashboard that displays navigation information. Not only is it installed, but a display device is also installed in front of the passenger seat.

A display is installed all the way to the front of the dashboard (or above the glove box) in front of the passenger seat, including the instrument panel in front of the driver's seat and the center fascia between the driver's seat and the passenger seat. In particular, if all of these are installed as one display, it gives the vehicle occupants a sense of openness and creates a sense of openness in the vehicle. It can make the interior look sophisticated, so it is a recent trend of being applied to vehicle interior design.

Since the dashboard of a vehicle is curved rather than straight, in order to mount a display on the front of the vehicle dashboard, an organic light-emitting or inorganic light-emitting display device made of a plastic substrate whose shape can be changed has no choice but to be adopted. Additionally, since the organic light emitting display device has almost no viewing angle restrictions and displays black well, it is advantageous for the driver to check the navigation displayed on the center fascia.

Meanwhile, if the display inside the vehicle is too bright, it is difficult for the driver to look ahead, which interferes with safe driving of the vehicle. Therefore, it is advantageous to keep the display brightness relatively low. However, when a navigation map related to vehicle operation is displayed on the display on the center fascia, which is relatively far from the driver's seat, and the driver receives guidance on the route to the destination on the map, if the brightness of the display is low, the driver cannot use the information provided by the navigation. It may be difficult to recognize quickly.

However, if the output brightness of the display is increased, the problem of increased power consumption occurs because the display area is large in a situation where the entire front of the dashboard is equipped with a display. Additionally, in an organic light emitting display, if the output luminance is increased, an afterimage phenomenon in which the image of the previous frame remains may occur.

In this specification, the embodiment selectively processes only the image data of the area where the driver's gaze stays on the display mounted on the front of the vehicle's dashboard, but increases the luminance of the area and adjusts the thickness of the line included in the area, The visibility of content displayed on the display can be increased.

Figure 2 shows an embodiment of processing the image of the area to increase the visibility of the area where the driver's gaze rests. The picture bordered by a circle in Figure 2 is an enlarged view of the area where the driver's gaze rests, The luminance of an area is raised and the thickness of text or lines contained in the area is adjusted.

First, check the area where the driver's gaze is directed on the vehicle's display, determine the size of the area, increase the luminance of the image data to be displayed in the area, and adjust the thickness of the lines or text included in the image data upward. , the visibility of content displayed in that area can be increased.

The area where the driver's gaze is directed can be confirmed through sensor signals provided by the eye tracking sensor installed inside the vehicle. Additionally, illuminance is referred to when adjusting the thickness of a line or text, and illuminance information can be provided by an illuminance sensor installed inside the vehicle.

Figure 3 shows the display device as functional blocks. The display device of FIG. 3 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. 3 may be integrated in whole or in part within the drive IC. The data driving circuit 12 and the gate driving circuit (13) can also be combined to form one driving circuit.

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.

In the display panel 10, a pixel array is formed in a display area on a plastic substrate, an encapsulation layer covering the pixel array is disposed, and a sealant is applied to a non-display area on the plastic substrate to buffer external shock and prevent moisture from entering the pixel array. Avoid doing so.

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 emitting light in the pixel to which the data voltage is written. 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.

One pixel unit may consist of three subpixels, including a red subpixel, a green subpixel, and a blue subpixel, or four subpixels, including a red subpixel, a green subpixel, a blue subpixel, and a white subpixel. , but is not limited thereto. 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. 4 described below.

The timing controller 11 performs image processing on image data (RGB) transmitted from an external host system (not shown) and supplies it to the data driving circuit 12. In addition, the timing controller 11 receives eye tracking information (ETI) and illuminance information (II) from the host system or a separate sensor, and determines the area where the driver's gaze stays based on this. And image processing to increase driver visibility can be performed on the image data (or content) of the determined area.

Image processing to increase visibility of content can be implemented through a data conversion unit, and the data conversion unit included in the timing controller 11 will be described in detail below.

Additionally, the timing controller 11 receives timing signals such as a vertical synchronization signal (Vsync), a horizontal synchronization signal (Hsync), a data enable signal (DE), and a dot clock (DCLK) from the host system, and operates the data driving circuit. Control signals for controlling the operation timing of (12) and 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 source driver ICs.

Each source drive IC constituting 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 may be an AP (Application Processor) or a main board that processes vehicle driving information, vehicle interior information, entertainment information, navigation information, etc. The host system may receive eye tracking information (ITI) and illuminance information (II) from the eye tracking sensor and the illuminance sensor and transmit them to the timing controller 11.

Figure 4 shows an example of an organic light emitting pixel circuit, and Figure 5 shows signals related to driving in the pixel circuit of Figure 4. The pixel circuit in FIG. 4 is only an example, and the pixel circuit to which embodiments of this specification are applied is not limited to FIG. 4.

The pixel circuit in FIG. 4 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 4 is for pixels placed on the nth horizontal line (or pixel line). The operation of the pixel circuit in FIG. 4 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. 6 shows an operation flowchart of an image processing method for increasing the visibility of the boosting area where the driver's gaze rests. The operation flowchart of FIG. 6 is performed in the data conversion unit included in the timing controller 11, and data conversion is performed. A unit may consist of all or part of an operation module corresponding to each step of the operation flowchart.

The eye tracking sensor installed inside the vehicle tracks the driver's eyes and detects the direction the driver's gaze is directed or the location where the gaze reaches (Eye-Tracking), and sends the detected eye tracking information (ETI) to the timing controller 11. Transmitted at predetermined time intervals.

The data conversion unit included in the timing controller 11 can specify the area where the user's gaze stays, that is, the boosting area, based on the eye tracking information (EIT) transmitted by the eye tracking sensor (Boosting Area Determination), and this operation The module that performs may be referred to as a boosting area determination unit.

The data conversion unit determines how much to increase the luminance level of the determined boosting area, and can determine the luminance level to be increased based on the luminance information (II) provided by the illuminance sensor and the luminance of the boosting area (Luminance Boosting Level Determination), the module that performs this operation can be called a boosting level determination unit.

Additionally, the data conversion unit analyzes the image data of the determined boosting area to determine whether a line or text is included (Line Detection), and the module that performs this operation may be referred to as a line detection unit.

The data conversion unit determines how much to change the thickness of the line or text included in the boosting area (Line Width Determination), and distinguishes the line or text based on illuminance information (II) and luminance information of the line or text and background. The width or thickness of the line or text required to do so can be determined, and the module that performs this operation can be called a line thickness determination unit.

The data conversion unit changes the image data included in the boosting area by applying the luminance level and line thickness of the boosting area determined through the previous process (Luminance & Line Width Boosting), and the boosting area with an increased luminance level and other areas. The boundary of the image is smoothed (Boosting Area Boundary Processing), and the module that performs this operation can be called an image processing module. The process of gradually processing the luminance of the border of the boosting area may be performed after adjusting the luminance level of the boosting area and before adjusting the line thickness.

Below, each step of the operation flowchart of FIG. 6 will be described in detail.

Figure 7a shows a person's cognitive ability according to the viewing angle, and Figure 7b shows an example of determining the size of the boosting area to be image processed according to the distance from the eye.

Among the navigation-related contents displayed on the vehicle display, text, arrows, and icons are important contents to the driver. As shown in Figure 7a, a person's visual recognition ability is most accurate when the viewing angle is within 3 degrees, text can be recognized within a viewing angle of 10 degrees, and symbols such as icons can be recognized within a viewing angle of 20 degrees. Colors can be distinguished within a viewing angle of 30 degrees.

Since the driver must be able to identify text or symbols included in the navigation map to select the route to the destination using the navigation displayed on the display, a viewing angle of approximately 10 to 20 degrees is the target to improve visibility. It can be decided as a zone or boosting zone.

In FIG. 7B, assuming that the distance from the driver to the display on the front of the dashboard is about 50 cm, the boosting area corresponding to a viewing angle of 10 to 20 degrees may correspond to a circle with a diameter of about 18 cm to 36 cm.

Accordingly, the data conversion unit may check the location of the driver's gaze from the eye tracking information (ETI) and determine, for example, a circle with a diameter of about 20 cm as the boosting area, centered on the confirmed location.

Figure 8a is a graph showing the appropriate display brightness level according to illuminance, and Figure 8b shows an example of upwardly adjusting the brightness of the boosting area where the driver's gaze stays. Figure 8a is a paper published in the SPIE 2018 journal (Optimum This is an excerpt from data published in (display luminance depends on white luminance under various ambient illuminance conditions, MinKoo Kim, etc.).

FIG. 8A is a graph showing how the appropriate luminance for ensuring visibility of content displayed on a display varies depending on the ambient illuminance. The horizontal axis is the ambient illuminance and the vertical axis is the display luminance. This reflects the results of multiple experimenters scoring the content from 1 to 5 under various illumination and luminance conditions.

In the graph of Figure 8a, three lines lead upward to the right, indicating that as the surrounding illumination increases, the display luminance must be increased to improve human cognitive ability, and the line with a high recognition score is above the line with a low score, which means that even at the same illuminance, the line with a high recognition score is above the line with a low score. Higher luminance indicates higher cognitive ability.

In this way, in order to increase the visibility of the boosting area, the luminance of the boosting area must be adjusted in consideration of the surrounding illumination.

The data conversion unit adjusts the luminance of the boosting area to an appropriate level according to the results of FIG. 8A, based on the illuminance information (II) output by the illuminance sensor by detecting the illuminance of the vehicle interior. The specifications and power consumption of the display device are adjusted. Considering this, the luminance level can be adjusted by selecting one of the 3-point level to the maximum 5-point level in the graph of FIG. 8A or a value in between. Figure 8b shows that the luminance level is adjusted upward so that the boosting area has higher luminance than the surrounding area, so that lines and arrows are displayed more clearly.

Figure 9 shows an operation flowchart for a method of adjusting the thickness of a line in a boosting area according to illuminance to increase visibility.

The data conversion unit first analyzes the image data in the boosting area and detects lines or text (Line Detection).

The data conversion unit calculates the luminance of the detected line or text and the luminance of the background or content around the line, and calculates the difference in luminance between the line and the surrounding area.

The data conversion unit determines the minimum thickness (or threshold thickness) (W-th) of the line required for humans to recognize the line based on the illuminance information (II) provided by the illuminance sensor and the luminance difference data between the line and its surroundings. , At this time, a lookup table that reflects the results of studying the minimum contrast sensitivity (CS) value depending on the illuminance can be used. Details related to the minimum CS lookup table are described below with reference to FIGS. 11 and 12.

If the thickness (Line Width) of the line or text in the boosting area is greater than the threshold thickness (W-th), the current line or text is kept unchanged. Otherwise, the thickness of the line or text is adjusted to determine the threshold thickness (W-th). ) larger than that.

Figure 10 compares the results of processing the boundaries of the boosting area.

When the luminance level of the boosting area is increased, as shown in the left picture of FIG. 10, the luminance is displayed at the boundary between the boosting area and the remaining area with a sharp change, thereby increasing the sense of heterogeneity in the image at the boundary.

As shown in the right figure of FIG. 10, gradually changing the luminance and/or line thickness at the border of the boosting area, that is, adjusting the luminance of the boosting area so that the luminance gradually decreases near the border of the boosting area, a sense of heterogeneity can be reduced at the border. It can be reduced, and a linear function or a gentle curve function can be applied as an algorithm to gradually change the luminance.

Figures 11A to 11C illustrate the process of generating a lookup table to be referenced when determining the thickness of a line for each illuminance.

Figure 11a is a graph showing the relationship between line thickness and contrast sensitivity (CS). The horizontal axis indicates CPD (Cycles Per Degree), a variable related to line thickness, and the vertical axis indicates contrast sensitivity (CS). CPD, a horizontal axis variable, is a value inversely proportional to the line thickness because it indicates how many pairs of black and white lines there are in an angle range of 1 degree. In FIG. 11A, the contrast sensitivity is highest at a certain line thickness and decreases as the line thickness increases or decreases.

From the line thickness with the highest contrast sensitivity, the contrast sensitivity gradually decreases when the line thickness becomes thinner (when the CDP value becomes larger or the curve moves to the right), and when the line thickness becomes thicker (when the CDP value becomes smaller or When the curve moves to the left) the contrast sensitivity decreases rapidly. Additionally, when illuminance is low, contrast sensitivity is higher than when illuminance is high.

First, a sensitivity curve corresponding to the illuminance information (II) input from the illuminance sensor is selected from the plurality of contrast sensitivity curves in FIG. 11a. Since the illuminance in FIG. 11a is 100 lux, the sensitivity curve corresponding to 100 lux, in FIG. 11 Select the top curve (①).

Select an arbitrary line thickness and find the contrast sensitivity value (CS) from the 100lux sensitivity curve (②).

Afterwards, based on the equation in FIG. 11b, the minimum luminance difference (?Y) required for a line with the corresponding contrast sensitivity (CS) to be recognized is calculated (③). In the equation in FIG. 11b, CS is the value corresponding to the line thickness. It is a contrast sensitivity value, Yref indicates the minimum value of the luminance of the line and the luminance of the background around the line, and α is a value that changes depending on the illuminance. When a line or text is black, the luminance of the line is lower than the luminance of the background, so Yref can be set to the luminance of the line. Conversely, when the line is bright, the luminance of the background is lower than the luminance of the line, so Yref can be set to the luminance of the background. It can be done with a luminance of .

Calculate the minimum luminance difference (?Y) by changing the line thickness (CS) and line luminance (Yref), and complete the minimum luminance difference table for 100 lux (④).

Afterwards, change the illuminance and select the sensitivity curve of Figure 11a, calculate the minimum luminance difference (?Y) while changing the line thickness and line luminance at the changed illuminance, complete the minimum luminance difference table for the corresponding illuminance, and By repeating the above-described process (① to ④) while changing , a minimum luminance difference table is generated for a plurality of illuminances (⑤).

The completed table can be stored in a memory provided in the timing controller 11, and the table can be recorded when the display device is shipped and updated after shipping.

FIG. 12A graphically illustrates the relationship between line thickness and contrast sensitivity, and FIG. 12B illustrates the process of determining the line thickness with reference to the lookup table generated through the process of FIG. 11.

The data conversion unit refers to the minimum luminance difference table stored in the memory and determines the thickness of the line based on the illuminance information (II) output by the illuminance sensor, the luminance of the line (or text) in the boosting area, and the luminance of the background around the line. You can decide.

In FIG. 12B, since the illuminance information output by the illuminance sensor is 100 lux, the data conversion unit selects and refers to the table corresponding to 100 lux from the plurality of minimum luminance difference tables stored in the memory.

Additionally, the data conversion unit analyzes the line or text included in the boosting area and calculates the thickness of the line, the luminance of the line, and the luminance of the background around the line. The luminance of the line is 20 nt and the luminance of the background is 23.5 nit. The contrast sensitivity value corresponding to the thickness of the line calculated from the contrast sensitivity curve corresponding to 100 lux corresponds to 20CS.

In the minimum luminance difference table corresponding to 100lux, when the CS value is 20 and the Yref value (same as the luminance of the line) is 20, the minimum luminance difference value is 7.0 (①), so the difference between the luminance of the line and the background is 3.5 ( =(23.5-20))nit, which is smaller than the minimum luminance difference value. In other words, it is difficult for humans to recognize the line at 100 lux illumination.

Since only the thickness of the line is adjusted without changing the luminance (Yref value) of the line, the data conversion unit determines that in the 100lux table of FIG. 12b, the minimum luminance difference in the row where Yref is 20 is greater than 3.5 between the luminance of the line and the background. Find the small value of 3.2(?), and find the CS value of 40 corresponding to the minimum luminance difference(?). That is, when the contrast sensitivity is a line thickness corresponding to 40, a line with a luminance of 20 nit and a surrounding luminance of 23.5 nit can be identified at an illumination intensity of 100 lux.

Afterwards, the data conversion unit finds the thickness of the line with a CS value of 40 in the 100 lut contrast sensitivity curve and adjusts the thickness of the line to a thickness corresponding to CS 40.

As shown in Figure 11a, to increase the CS value, the thickness of the line must also be increased.

When the boosting area is determined through eye tracking, the data conversion unit first increases the overall luminance of the boosting area as described with reference to FIGS. 8A and 8B, thereby increasing not only the luminance of the line or text included in the boosting area but also the surrounding background. Brightness also increases.

Therefore, when determining the thickness of the line described with reference to FIGS. 12A and 12B, the luminance of the line and the luminance of the background should be values obtained after increasing the overall luminance of the boosting area.

Figure 13 shows the results of image processing of the area where the driver's gaze remains at night according to the operation flowchart of Figure 6.

Figure 13 is a simulation of the situation when an image captured by the vehicle's front camera is displayed on the vehicle's internal display. Because it is night, the road guide sign itself on the vehicle display where the driver's gaze rests is dark, making it difficult to identify (Original Image) .

In the first step, by selecting the area around the guide sign where the driver's gaze rests as the boosting area through eye tracking and increasing the luminance of the boosting area (Step 1: Luminance Boosting), the presence of the road guide sign can be confirmed, and the sign has It is not easy to identify the existing text. Additionally, because the luminance of the boosting area has been raised, the surrounding area and boundaries are clearly revealed.

In the second step, the luminance is gradually adjusted at the boundary between the boosting area and the surrounding area (Step 2: Gradation), so that road signs in the boosting area can be recognized, but the boundary between the boosting area and the surrounding area is difficult to see. Changes in luminance are natural.

In the third step, the thickness of the line or text included in the boosting area was adjusted (Step 3: Line Width Adjustment), and the text written on the application guide sign became clear enough for drivers to recognize it.

In this way, by adjusting the luminance and line thickness of the boosting area where the driver's gaze stays, the visibility of the content displayed in the boosting area is improved, which reduces the need for the driver to look at the boosting area for a long time, helping to drive the vehicle safely. can be given.

Meanwhile, a camera-type eye tracking device equipped with an illumination sensor can be used as the eye tracking sensor, and the eye tracking information and illumination information can be transmitted to the timing controller 11 through the AP. Eye tracking information can be used by the AP to determine whether the driver is drowsy.

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

A display device according to an embodiment includes a display panel for displaying an image having a plurality of pixels connected to a gate line and a data line; a driving circuit for supplying data voltages to a plurality of pixels by driving a gate line and a data line; and a timing controller for selecting a first area from the input image data, adjusting the luminance of the first area and the thickness of the line included in the first area based on the illuminance value, and transmitting the information to the driving circuit. It is characterized by

In one embodiment, the timing controller may select the first area based on eye tracking information.

In one embodiment, the timing controller may adjust the luminance of the first area to be higher as the illuminance value increases.

In one embodiment, the timing controller may adjust the luminance of the first area so that the luminance gradually decreases at the boundary of the first area.

In one embodiment, the timing controller may change the thickness of the line included in the first area based on the illuminance value, the first luminance of the line, and the second luminance around the line.

In one embodiment, the display device further includes a memory that stores a table that defines a luminance difference value for each of a plurality of illuminance values and a combination of a plurality of values corresponding to line thickness and a plurality of luminance values. It can be.

In one embodiment, the timing controller finds a first table corresponding to the luminance value, and determines a line thickness in the first table corresponding to the smaller of the first luminance and the second luminance and the difference value between the first luminance and the second luminance. may be determined, and the thickness of the line included in the first area may be adjusted according to the determined line thickness.

In one embodiment, after adjusting the luminance of the first area, the timing controller adjusts the luminance of the first area based on the adjusted first luminance of the line and the adjusted second luminance around the line according to the adjustment of the luminance of the first area. You can change the thickness of the lines included in .

An image processing method in a display device according to another embodiment includes selecting a first area from input image data; increasing the luminance of the first area based on the illuminance value; adjusting the thickness of a line included in the first area based on the illuminance value; and displaying image data in the first area through image processing.

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 (15)

A display panel for displaying an image including a plurality of pixels connected to a gate line and a data line;
a driving circuit for driving the gate line and the data line to supply data voltages to the plurality of pixels; and
A timing controller that processes input image data and transmits it to the driving circuit,
The timing controller includes a data conversion unit,
The data conversion unit,
a boosting area determination unit that determines a first area from the input image data;
a boosting level determination unit that determines the luminance level of the first area using the illuminance value output by the luminance and illuminance sensor of the first area by detecting the illuminance of the vehicle interior;
a line detection unit that analyzes the image data of the first area and detects whether a line or text is included;
a line thickness determination unit that determines the thickness of a line or text in the first area; and
An image processing module that changes image data included in the first area by applying the luminance level and line thickness of the first area and smoothes the boundary between the first area where the luminance level is increased and other areas. do,
The process of gradually processing the luminance of the border of the first area is performed after adjusting the luminance level of the first area and before adjusting the line thickness. According to claim 1,
The timing controller selects the first area based on eye tracking information. According to claim 1,
The timing controller is configured to adjust the luminance of the first area to be higher as the illuminance value increases. According to claim 1,
The timing controller is configured to adjust the luminance of the first area so that the luminance gradually decreases at the boundary of the first area. According to claim 1,
The timing controller changes the thickness of the line included in the first area based on the illuminance value, the first luminance of the line, and the second luminance around the line. According to clause 5,
A display device further comprising a memory that stores a table defining, for each of the plurality of illuminance values, a luminance difference value for each of a plurality of values corresponding to line thickness and a combination of the plurality of luminance values. According to clause 6,
The timing controller searches a first table corresponding to the illuminance value, and finds a line in the first table corresponding to a smaller value of the first luminance and the second luminance and a difference value between the first luminance and the second luminance. A display device characterized in that the thickness is determined and the thickness of the line included in the first area is adjusted according to the determined line thickness. According to clause 5,
After adjusting the luminance of the first area, the timing controller adjusts the first luminance of the line according to the adjustment of the luminance of the first area and the adjusted second luminance around the line. A display device characterized by changing the thickness of a line included in an area. determining a first area from input image data;
determining the luminance level of the first area using the illuminance value output by the luminance and illuminance sensor of the first area by detecting the illuminance inside the vehicle;
Analyzing the image data of the first area to detect whether it contains a line or text;
determining a thickness of a line or text in the first area; and
Applying the luminance level and line thickness of the first area to change image data included in the first area and smoothing the boundary between the first area where the luminance level is increased and other areas,
The process of gradually processing the luminance of the border of the first area is performed after adjusting the luminance level of the first area and before adjusting the line thickness. According to clause 9,
An image processing method in a display device, wherein the selecting step selects the first area based on eye tracking information. According to clause 9,
In the upward step, the luminance of the first area is adjusted to be higher as the illuminance value increases. According to clause 9,
The image processing method in a display device, wherein the upward step adjusts the luminance of the first area so that the luminance gradually changes at the boundary of the first area. According to clause 9,
The adjusting step includes changing the thickness of the line included in the first area based on the illuminance value, the first luminance of the line, and the second luminance around the line. method. According to claim 13,
The adjusting step includes selecting a first table corresponding to the illuminance value among a plurality of tables in which luminance difference values for each combination of a plurality of values corresponding to line thickness and a plurality of luminance values are defined for each of the plurality of illuminance values. Find and determine a line thickness corresponding to a smaller value of the first luminance and the second luminance and a difference value between the first luminance and the second luminance in the first table, and determine the first luminance according to the determined line thickness. An image processing method in a display device, characterized in that the thickness of a line included in an area is adjusted. According to claim 13,
The adjusting step includes increasing the luminance of the first area and then adjusting the first luminance of the line according to the adjustment of the luminance of the first area and the adjusted second luminance around the line. 1 An image processing method in a display device characterized by changing the thickness of a line included in an area.

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