KR20240155038A - Display device and operating method thereof - Google Patents

Abstract

A display device according to an embodiment of the present disclosure may include a display panel, a backlight unit that outputs light to the display panel, and a control unit that reduces light output intensity of the backlight unit according to a remaining amount of the battery when the display device is powered by a battery, adjusts a gain of a dynamic tone mapping curve and a gain of a dynamic contrast curve for an input image signal according to the reduction in the light output intensity, and outputs an output image signal generated according to the adjustment of each gain to the display panel.

Description

DISPLAY DEVICE AND OPERATING METHOD THEREOF

The present disclosure relates to a display device and a method of operating the same.

Liquid crystal displays using an active matrix driving method display images using a thin film transistor (hereinafter referred to as “TFT”) as a switching element.

Liquid crystal displays (LCDs) can be miniaturized compared to cathode ray tubes (CRTs), and are therefore used in display devices such as portable information devices, office equipment, and computers, as well as in televisions, quickly replacing cathode ray tubes.

Transmissive liquid crystal displays, which account for the majority of liquid crystal displays, display images by modulating the light incident from the backlight unit by controlling the electric field applied to the liquid crystal layer.

For display devices equipped with batteries, when images are played back through the display device using the battery, the light output intensity of the backlight unit may be reduced to prevent waste of power consumption.

If the light output intensity of the backlight unit is reduced, the image may become dark and disturb the user's viewing experience.

Additionally, even in bright outdoor environments, the perceived brightness also decreases due to a decrease in the light output of the backlight unit, causing the image to become dark.

The purpose of the present disclosure is to prevent an image from becoming dark due to a decrease in the light output intensity of a backlight unit by compensating for an image signal when a display device is powered by a battery.

The present disclosure aims to compensate an image signal according to measured illuminance when a display device is powered by a battery.

A display device according to an embodiment of the present disclosure may include a display panel, a backlight unit that outputs light to the display panel, and a control unit that reduces light output intensity of the backlight unit according to a remaining amount of the battery when the display device is powered by a battery, adjusts a gain of a dynamic tone mapping curve and a gain of a dynamic contrast curve for an input image signal according to the reduction in the light output intensity, and outputs an output image signal generated according to the adjustment of each gain to the display panel.

According to an embodiment of the present disclosure, a method for operating a display device including a display panel and a backlight unit that outputs light to the display panel may include, when the display device is powered by a battery, a step of reducing light output intensity of the backlight unit according to a remaining amount of the battery, a step of adjusting a gain of a dynamic tone mapping curve and a gain of a dynamic contrast curve for an input image signal according to the reduction in the light output intensity, and a step of outputting an output image signal generated according to the adjustment of each gain to the display panel.

According to the present disclosure, even if the light output intensity of the backlight unit is reduced, the screen can be prevented from darkening through compensation of the image signal. Accordingly, the user's viewing experience can be improved.

According to the present disclosure, when viewing a video outdoors in a bright environment, the video signal can be processed to enable viewing a brighter screen, thereby improving the user's video viewing experience.

FIG. 1 is a drawing illustrating a display device according to one embodiment of the present disclosure.
Figure 2 is a block diagram illustrating the configuration of the display device of Figure 1.
Figure 3 is an example of an internal block diagram of the control unit of Figure 2.
FIG. 4a is a drawing illustrating a control method of the remote control device of FIG. 2.
Fig. 4b is an internal block diagram of the remote control device of Fig. 2.
Figure 5 is an internal block diagram of the power supply unit and display of Figure 2.
Figure 6 is an example drawing showing the arrangement of a liquid crystal display panel and light sources in the case of an edge-type backlight unit.
Figure 7 is an example drawing showing the arrangement of liquid crystal display panels and light sources in the case of a direct-type backlight unit.
FIG. 8 is a drawing explaining an operating method of a display device according to an embodiment of the present disclosure.
FIG. 9 is a graph showing the relationship between the light output intensity of a backlight unit and the remaining battery capacity according to one embodiment of the present disclosure.
FIG. 10 is a drawing illustrating a DTM curve with adjusted gain according to an embodiment of the present disclosure.
FIG. 11 is a drawing illustrating a DC curve with adjusted gain according to an embodiment of the present disclosure.
FIG. 12 is a diagram illustrating an example of adjusting the gain of a DTM curve and the gain of a DC curve when power is supplied to a display device through a battery and the illuminance measured through an illuminance sensor is above a certain illuminance according to an embodiment of the present disclosure.
FIG. 13 is a drawing illustrating a method for determining whether an embodiment of the present disclosure described in FIG. 8 is applied.

Hereinafter, the present specification will be described in more detail with reference to the drawings.

The suffixes "module" and "part" used for components in the following description are given simply for the convenience of writing this specification, and do not in themselves impart any particularly important meaning or role. Accordingly, the above "module" and "part" may be used interchangeably.

Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The terms are used only to distinguish one component from another.

Singular expressions include plural expressions unless the context clearly indicates otherwise.

In this application, it should be understood that terms such as “comprises” or “have” are intended to specify the presence of a feature, number, step, operation, component, part or combination thereof described in the specification, but do not exclude in advance the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts or combinations thereof.

FIG. 1 is a drawing illustrating a display device according to one embodiment of the present disclosure.

Referring to the drawing, the display device (100) may include a display unit (180).

Meanwhile, the display unit (180) can be implemented as any one of various panels.

In the present disclosure, the display unit (180) is assumed to have a liquid crystal display panel (LCD panel). Hereinafter, the display device (100) may be a liquid crystal display device.

Meanwhile, the display device (100) of Fig. 1 can be a monitor, TV, tablet PC, mobile terminal, etc.

Figure 2 is a block diagram illustrating the configuration of the display device of Figure 1.

Referring to FIG. 2, the display device (100) may include a broadcast receiving unit (130), an external device interface unit (135), a storage unit (140), a user input interface unit (150), a control unit (170), a wireless communication unit (173), a display unit (180), an audio output unit (185), and a power supply unit (190).

The broadcast receiving unit (130) may include a tuner (131), a demodulator (132), and a network interface unit (133).

The tuner (131) can select a specific broadcast channel according to a channel selection command. The tuner (131) can receive a broadcast signal for the selected specific broadcast channel.

The demodulator (132) can separate the received broadcast signal into a video signal, an audio signal, and a data signal related to the broadcast program, and can restore the separated video signal, audio signal, and data signal into a form that can be output.

The network interface unit (133) can provide an interface for connecting the display device (100) to a wired/wireless network including the Internet.

The external device interface unit (135) can receive an application or a list of applications in an adjacent external device and transmit it to the control unit (170) or storage unit (140).

The external device interface unit (135) can provide a connection path between the display device (100) and the external device. The external device interface unit (135) can receive one or more of images and audio output from an external device connected wirelessly or wiredly to the display device (100) and transmit them to the control unit (170).

The external device interface unit (135) may include a plurality of external input terminals. The plurality of external input terminals may include an RGB terminal, one or more HDMI (High Definition Multimedia Interface) terminals, and a component terminal.

A video signal of an external device input through the external device interface unit (135) can be output through the display unit (180). A voice signal of an external device input through the external device interface unit (135) can be output through the audio output unit (185).

An external device that can be connected to the external device interface unit (135) may be any one of a set-top box, a Blu-ray player, a DVD player, a game console, a sound bar, a smartphone, a PC, a USB memory, and a home theater, but this is only an example.

The storage unit (140) stores programs for each signal processing and control within the control unit (170) and can store processed images, voices, or data signals.

In addition, the storage unit (140) may perform a function for temporary storage of video, audio, or data signals input from an external device interface unit (135) or a network interface unit (133), and may also store information about a specific image through a channel memory function.

The user input interface unit (150) can transmit a signal input by the user to the control unit (170), or transmit a signal from the control unit (170) to the user. For example, the user input interface unit (150) can receive and process control signals such as power on/off, channel selection, and screen setting from the remote control device (200) according to various communication methods such as Bluetooth, WB (Ultra Wideband), ZigBee, RF (Radio Frequency) communication, or infrared (IR) communication, or process the control signals from the control unit (170) to be transmitted to the remote control device (200).

In addition, the user input interface unit (150) can transmit control signals input from local keys (not shown) such as a power key, channel key, volume key, and setting value to the control unit (170).

An image signal processed in the control unit (170) may be input to the display unit (180) and displayed as an image corresponding to the image signal. In addition, an image signal processed in the control unit (170) may be input to an external output device through the external device interface unit (135).

The voice signal processed in the control unit (170) can be output as audio to the audio output unit (185). In addition, the voice signal processed in the control unit (170) can be input to an external output device through the external device interface unit (135).

In addition, the control unit (170) can control the overall operation within the display device (100).

The control unit (170) enables a video signal or audio signal from an external device, for example, a camera or camcorder, input through the external device interface unit (135) to be output through the display unit (180) or audio output unit (185) in accordance with an external device video playback command received through the user input interface unit (150).

Meanwhile, the control unit (170) can control the display unit (180) to display an image, and for example, can control the display unit (180) to display a broadcast image input through the tuner (131), an external input image input through the external device interface unit (135), an image input through the network interface unit, or an image stored in the storage unit (140). In this case, the image displayed on the display unit (180) can be a still image or a moving image, and can be a 2D image or a 3D image.

In addition, the control unit (170) can control the playback of content stored in the display device (100), received broadcast content, or external input content input from the outside, and the content can be in various forms such as broadcast images, external input images, audio files, still images, connected web screens, and document files.

The wireless communication unit (173) can perform communication with an external device through wired or wireless communication. The wireless communication unit (173) can perform short range communication with an external device.

To this end, the wireless communication unit (173) can support short-distance communication using at least one of Bluetooth™, BLE (Bluetooth Low Energy), RFID (Radio Frequency Identification), Infrared Data Association (IrDA), UWB (Ultra Wideband), ZigBee, NFC (Near Field Communication), Wi-Fi (Wireless-Fidelity), Wi-Fi Direct, and Wireless USB (Wireless Universal Serial Bus) technologies.

The display unit (180) can generate a driving signal by converting a video signal, data signal, OSD signal processed by the control unit (170) or a video signal, data signal, etc. received from the external device interface unit (135) into R, G, B signals, respectively.

Meanwhile, since the display device (100) illustrated in FIG. 1 is only an embodiment of the present disclosure, some of the illustrated components may be integrated, added, or omitted depending on the specifications of the display device (100) actually implemented.

That is, two or more components can be combined into one component, or one component can be divided into two or more components, as needed.

In addition, the functions performed in each block are intended to explain embodiments of the present disclosure, and the specific operations or devices thereof do not limit the scope of the present disclosure.

The audio output unit (185) receives a signal processed by the control unit (170) and outputs it as voice.

The power supply unit (190) supplies power to the entire display device (100). In particular, power can be supplied to a control unit (170) that can be implemented in the form of a system on chip (SOC), a display unit (180) for displaying images, and an audio output unit (185) for audio output.

Specifically, the power supply unit (190) may be equipped with a converter that converts AC power into DC power and a dc/dc converter that converts the level of the DC power.

The remote control device (200) transmits user input to the user input interface unit (150).

To this end, the remote control device (200) can use Bluetooth, RF (Radio Frequency) communication, IR (Infrared) communication, UWB (Ultra Wideband), ZigBee, etc. In addition, the remote control device (200) can receive images, voices, or data signals output from the user input interface unit (150) and display or output them as voices on the remote control device (200).

Figure 3 is an example of an internal block diagram of the control unit of Figure 2.

Referring to the drawings, a control unit (170) according to an embodiment of the present disclosure may include a demultiplexer (310), an image processing unit (320), a processor (330), an OSD generation unit (340), a mixer (345), a frame rate conversion unit (350), and a formatter (360). In addition, an audio processing unit (not shown) and a data processing unit (not shown) may be further included.

The demultiplexer (310) demultiplexes the input stream. For example, if MPEG-2 TS is input, it can be demultiplexed to separate it into video, audio, and data signals, respectively. Here, the stream signal input to the demultiplexer (310) may be a stream signal output from the tuner (110), the demodulator (120), or the external device interface (130).

The image processing unit (320) can perform image processing of a demultiplexed image signal. To this end, the image processing unit (320) can be equipped with an image decoder (325) and a scaler (335).

The video decoder (325) decodes the demultiplexed video signal, and the scaler (335) scales the resolution of the decoded video signal so that it can be output on the display unit (180).

The video decoder (325) can be equipped with decoders of various standards. For example, it can be equipped with an MPEG-2, H.264 decoder, a 3D video decoder for color images and depth images, a decoder for multi-view images, etc.

The processor (330) can control the overall operation within the display device (100) or within the control unit (170). For example, the processor (330) can control the tuner (110) to select (tune) an RF broadcast corresponding to a channel selected by a user or a pre-stored channel.

Additionally, the processor (330) can control the display device (100) by a user command or internal program input through the user input interface unit (150).

Additionally, the processor (330) can perform data transmission control with the network interface unit (135) or the external device interface unit (130).

In addition, the processor (330) can control the operation of the demultiplexing unit (310), the image processing unit (320), the OSD generation unit (340), etc. within the control unit (170).

The OSD generation unit (340) generates an OSD signal based on a user input or on its own. For example, based on a user input signal, a signal for displaying various information as graphics or text on the screen of the display unit (180) may be generated. The generated OSD signal may include various data such as a user interface screen of the display device (100), various menu screens, widgets, and icons. In addition, the generated OSD signal may include a 2D object or a 3D object.

In addition, the OSD generation unit (340) can generate a pointer that can be displayed on the display unit (180) based on a pointing signal input from the remote control device (200). In particular, such a pointer can be generated in the pointing signal processing unit, and the OSD generation unit (340) can include such a pointing signal processing unit (not shown). Of course, the pointing signal processing unit (not shown) can also be provided separately, rather than being included in the OSD generation unit (340).

The mixer (345) can mix the OSD signal generated by the OSD generation unit (340) and the decoded image signal processed by the image processing unit (320). The mixed image signal is provided to the frame rate conversion unit (350).

The frame rate converter (FRC) (350) can convert the frame rate of the input video. Meanwhile, the frame rate converter (350) can also output as is without a separate frame rate conversion.

Meanwhile, the formatter (360) can change the format of an input video signal into a video signal for display on a display and output it.

The formatter (360) can change the format of the video signal. For example, the format of the 3D video signal can be changed to any one of various 3D formats, such as a side-by-side format, a top-down format, a frame sequential format, an interlaced format, and a checker box format.

Meanwhile, the audio processing unit (not shown) in the control unit (170) can perform audio processing of the demultiplexed audio signal. For this purpose, the audio processing unit (not shown) can be equipped with various decoders.

Additionally, the audio processing unit (not shown) within the control unit (170) can process bass, treble, volume control, etc.

The data processing unit (not shown) in the control unit (170) can perform data processing of a demultiplexed data signal. For example, if the demultiplexed data signal is an encoded data signal, it can be decoded. The encoded data signal can be electronic program guide information including broadcast information such as the start time and end time of a broadcast program broadcast on each channel.

Meanwhile, the block diagram of the control unit (170) illustrated in Fig. 3 is a block diagram for one embodiment of the present disclosure. Each component of the block diagram may be integrated, added, or omitted depending on the specifications of the control unit (170) actually implemented.

In particular, the frame rate converter (350) and the formatter (360) are not provided within the control unit (170), but may be provided separately, or may be provided separately as one module.

Figure 4 is an internal block diagram of the power supply unit and display module of Figure 2.

Referring to the drawing, a display module (180) based on a liquid crystal display panel (LCD panel) may include a liquid crystal display panel (210), a driving circuit unit (230), a backlight unit (250), and a backlight dimming control unit (510).

A liquid crystal display panel (210) includes a first substrate on which a plurality of gate lines (GL) and data lines (DL) are arranged in a matrix form to cross each other to display an image, and on which thin film transistors and pixel electrodes connected thereto are formed in the crossing areas, a second substrate provided with a common electrode, and a liquid crystal layer formed between the first substrate and the second substrate.

The driving circuit unit (230) drives the liquid crystal display panel (210) through control signals and data signals supplied from the control unit (170) of Fig. 1. To this end, the driving circuit unit (230) includes a timing controller (232), a gate driver (234), and a data driver (236).

The timing controller (232) receives a control signal and R, G, B data signals, a vertical synchronization signal (Vsync), etc. from the control unit (170), controls the gate driver (234) and the data driver (236) in response to the control signal, rearranges the R, G, B data signals, and provides them to the data driver (236).

Under the control of the gate driver (234), the data driver (236), and the timing controller (232), the scanning signal and the image signal are supplied to the liquid crystal display panel (210) through the gate line (GL) and the data line (DL).

The backlight unit (250) supplies light to the liquid crystal display panel (210). To this end, the backlight unit (250) may include a plurality of light sources (252), a scan driving unit (254) that controls scanning driving of the light sources (252), and a light source driving unit (256) that turns the light sources (252) on/off.

A predetermined image is displayed using light emitted from a backlight unit (250) while the light transmittance of the liquid crystal layer is controlled by an electric field formed between the pixel electrode and the common electrode of the liquid crystal display panel (210).

The power supply unit (190) can supply a common electrode voltage (Vcom) to the liquid crystal display panel (210) and a gamma voltage to the data driver (236). In addition, it can supply driving power for driving a light source (252) to the backlight unit (250).

Meanwhile, the backlight unit (250) can be divided into a plurality of blocks and driven. The control unit (170) can control the display (180) to perform local dimming by setting a dimming value for each of the plurality of blocks. Specifically, the timing controller (232) outputs input image data (RGB) to the backlight dimming control unit (510), and the backlight dimming control unit (510) can calculate a dimming value for each of the plurality of blocks based on the input image data (RGB) received from the timing controller (232).

FIG. 5 is an example drawing showing the arrangement of liquid crystal display panels and light sources in the case of an edge-type backlight unit, and FIG. 6 is an example drawing showing the arrangement of liquid crystal display panels and light sources in the case of a direct-type backlight unit.

The liquid crystal display panel (210) may be divided into a plurality of virtual blocks as illustrated in FIGS. 5 and 6. In FIGS. 5 and 6, the liquid crystal display panel (210) is described as being evenly divided into 16 blocks (BL1 to BL16), but it should be noted that the present invention is not limited thereto. Each of the plurality of blocks may include a plurality of pixels.

The backlight unit (250) can be implemented as either an edge type or a direct type.

The edge-type backlight unit (250) has a structure in which a plurality of optical sheets and a light guide plate are laminated under a liquid crystal display panel (210), and a plurality of light sources are arranged on the side of the light guide plate.

When the backlight unit (250) is implemented as an edge-type backlight unit, the light sources are arranged on at least one of the upper and lower sides and at least one of the left and right sides of the liquid crystal display panel (210). In FIG. 5, it is described as an example that the first light source array (LA1) is arranged on the upper side of the liquid crystal display panel (210) and the second light source array (LA2) is arranged on the left side of the liquid crystal display panel (210). Each of the first and second light source arrays (LA1, LA2) includes a plurality of light sources (252) and a light source circuit board (251) on which the light sources (252) are mounted. In this case, the brightness of light incident on the first block (BL1) of the liquid crystal display panel (210) can be adjusted using the light sources (252A) of the first light source array (LA1) and the light sources (252B) of the second light source array (LA2) arranged at positions corresponding to the first block (BL1) of the liquid crystal display panel (210).

The direct-type backlight unit (250) has a structure in which a plurality of optical sheets and a diffusion plate are laminated under a liquid crystal display panel (210) and a plurality of light sources are arranged under the diffusion plate.

When the backlight unit (250) is implemented as a direct-type backlight unit, it is divided to correspond one-to-one to the blocks (BL1 to BL16) of the liquid crystal display panel (210) as shown in FIG. 6. In this case, the brightness of light incident on the first block (BL1) of the liquid crystal display panel (210) can be adjusted using the light sources (252) included in the first block (B1) of the backlight unit (250) arranged at a position corresponding to the first block (BL1) of the liquid crystal display panel (210).

The light sources (252) can be implemented as point light sources such as light emitting diodes (LEDs). The light sources (252) are turned on and off by receiving light source driving signals (LDS) from the light source driving unit (256). The light intensity of the light sources (252) can be adjusted according to the amplitude of the light source driving signals (LDS), and the lighting period can be adjusted according to the pulse width. The brightness of the light output by the light sources (252) can be adjusted according to the light source driving signals (LDS).

The light source driving unit (256) can generate light source driving signals (LDS) based on the dimming values of each block input from the backlight dimming control unit (510) and output them to the light sources (252). The dimming values of the blocks are values for implementing local dimming and can be the brightness of light output by the light sources (252).

FIG. 7 is a drawing explaining the process of an image becoming dark when a battery is used to provide power to a display device according to conventional technology.

In Fig. 7, the battery of the display device (100) may be included in the power supply unit (190) of Fig. 2 or may be provided separately from the display device (100).

When the battery is provided separately from the display device (100), the battery can supply power to the display device (100) through the power supply unit (190) or the external device interface unit (135).

Referring to FIG. 7, the display device (100) is playing an image (700) before being supplied with power from the battery. In this case, the display device (100) may be supplied with AC power.

The display device (100) is disconnected from AC power and receives power from the battery. In this way, the display device (100) reduces the light output intensity of the backlight unit (250) to reduce power consumption when the battery is in use.

That is, when the display device (100) uses the battery, the light output intensity of the backlight unit (250) is reduced so that the first graph (710) representing the brightness of the output image signal compared to the input image signal becomes the second graph (730).

The control unit (170) of the display device (100) transmits a dimming signal to the backlight dimming control unit (510) to reduce the light output intensity.

As the light output intensity of the backlight unit (250) decreases, the brightness of the image (700) becomes darker. Accordingly, the user views a dark image, which may deteriorate the user's viewing experience.

FIG. 8 is a flowchart for explaining an operating method of a display device according to an embodiment of the present disclosure.

Hereinafter, the battery may be included in the power supply unit (190) of the display device (100) or may be provided separately from the display device (100).

If the battery is provided separately from the display device (100), the battery may be connected to the external device interface unit (135) or power supply unit (190) of the display device (100).

Referring to FIG. 8, the control unit (170) of the display device (100) can determine whether use of the battery is detected (S801).

In one embodiment, the control unit (170) may determine that battery use has been detected when the display device (100) is powered by a battery.

In another embodiment, the control unit (170) may determine that battery use has been detected when the display device (100) is not supplied with AC power but is supplied with power from a battery.

The control unit (170) can identify power supplied from an AC power source and power supplied from a battery.

The control unit (170) can obtain the light output intensity of the backlight unit (250) according to the remaining battery capacity (S803).

The control unit (170) can obtain the remaining battery capacity when battery use is detected.

The control unit (170) can receive information about the remaining battery capacity from the battery.

The control unit (170) can obtain the light output intensity of the backlight unit (250) corresponding to the remaining amount of the acquired battery.

The storage unit (140) may store a lookup table indicating a correspondence between the remaining battery capacity and the light output intensity of the backlight unit (250).

The control unit (170) can read the light output intensity of the backlight unit (250) that matches the remaining battery level using the lookup table stored in the storage unit (140).

As the remaining battery power increases, the light output intensity of the backlight unit (250) may increase, and as the remaining battery power decreases, the light output intensity of the backlight unit (250) may decrease.

FIG. 9 is a graph showing the relationship between the light output intensity of a backlight unit and the remaining battery capacity according to one embodiment of the present disclosure.

Referring to FIG. 9, the light output graph (910) may be a graph showing the relationship between the light output intensity of the backlight unit (250) according to the remaining battery level.

The light output graph (910) may have a tendency to show that the light output intensity of the backlight unit (250) increases as the remaining battery capacity increases.

The effect ratio graph (930) may be a graph that shows how much of a change in the light output intensity of the backlight unit (250) will be applied depending on the remaining battery capacity.

Again, Figure 8 is explained.

The control unit (170) can adjust the gain of the dynamic tone mapping (DTM) curve and the gain of the dynamic contrast (DC) curve for the input image signal according to the acquired light output intensity (S805).

The control unit (170) can sequentially adjust the gain of the DTM curve and the gain of the DC curve when the light output intensity of the backlight unit (250) decreases.

That is, when the light output intensity of the backlight unit (250) decreases, the control unit (170) can adjust the gain of the DTM curve and then adjust the gain of the DC curve.

The control unit (170) can receive an input video signal from any one of the broadcast receiving unit (130), the external device interface unit (135), and the wireless communication unit (173).

A dynamic tone mapping curve can be a curve that represents the process of processing an output image signal for an input image signal in the RGB domain.

The control unit (170) can increase the gain of the dynamic tone mapping curve according to the decrease in the light output intensity of the backlight unit (250). To this end, the control unit (170) can process the input image signal so that the ratio of the value of the output image signal to the value of the input image signal exceeds 1 and has a value less than a preset value. The preset value may be a value set to prevent an excessively bright image from being output.

The control unit (170) can adjust the DTM curve to have a larger value than the straight line (1000) representing a 1:1 ratio, where the ratio of the input value of the input image signal to the output value of the output image signal is 1.

The control unit (170) can adjust the gain of the DTM curve to increase the color density of the input image signal. At the same time, the control unit (170) can adjust the DTM curve to make the slope of the curve of the portion corresponding to the high grayscale area gentle to minimize the deterioration of the signal discrimination ability in the high grayscale area.

The control unit (170) can perform dynamic tone mapping through a DTM curve with adjusted gain for an input image signal, and then perform dynamic contrast mapping through a DC curve with adjusted gain.

FIG. 10 is a drawing illustrating a DTM curve with adjusted gain according to an embodiment of the present disclosure.

Referring to (a) of Fig. 10, a straight line (1000) is shown where the ratio of input values to output values is 1:1.

The control unit (170) can adjust the DTM curve (1010) so that the APL (Average Picture Level) value of a point where the ratio of the input value of the input image signal to the output value of the output image signal is 1 has a larger value than the straight line (1000) representing a 1:1 ratio.

The control unit (170) can set an offset indicating the degree of adjustment of the DTM curve according to the amount of change in the light output intensity of the backlight unit (250).

The degree of adjustment of the DTM curve can be a value corresponding to the gain.

That is, the control unit (170) can change the first DTM curve (1031) to the second DTM curve (1033) based on the offset curve (1035) representing the offset, as shown in (b) of FIG. 10.

The offset curve (1033) may be a curve representing the difference between the output value of the first DTM curve (1031) and the output of the second DTM curve (1033).

Again, Figure 8 is explained.

The control unit (170) can process an input image signal through the DTM curve and then compensate for the processed image signal through the DC curve.

A DC curve can be a curve that represents the process of processing an output image signal versus an input image signal in the luminance (Y) domain.

The gain of the DC curve can be a parameter that adjusts the brightness of the image. As the gain of the DC curve increases, the contrast of bright areas can increase, and the contrast of dark areas can decrease.

As the gain of the DC curve decreases, the contrast in bright areas may decrease and the contrast in dark areas may increase.

The gain of the DC curve can range between 0 and 1, but this is only an example.

The control unit (170) can correct the brightness contrast of the image signal that changes through the DTM curve through the DC curve.

The control unit (170) can adjust the gain of the DC curve so that the ratio of the output value to the input value in the low grayscale area is less than 1, and the ratio of the output value to the input value in the high grayscale area is greater than 1.

FIG. 11 is a drawing illustrating a DC curve with adjusted gain according to an embodiment of the present disclosure.

Referring to FIG. 11, the control unit (170) can change the DTM curve (1010) of FIG. 10 (a) to the DC curve (1110) of FIG. 11 (a) to compensate for the image signal.

Input values smaller than h1 may correspond to low-grayscale areas, and input values larger than h1 may correspond to high-grayscale areas.

The control unit (170) can generate a DC curve (1110) so that the ratio of the output value to the input value in the low grayscale area is less than 1, and the ratio of the output value to the input value in the high grayscale area is greater than 1.

Referring to (b) of FIG. 11, an offset curve (1130) is illustrated that shows the degree of adjustment of the DC curve (1110) according to the amount of change in the light output intensity of the backlight unit (250).

The offset curve (1130) may be a curve representing the difference in output values between a base DC curve and a DC curve (1110) with adjusted gain according to the application of the DTM curve (1010).

Again, Figure 8 is explained.

The control unit (170) can output each output image signal with adjusted gain to the display panel (210) (S807).

According to an embodiment of the present disclosure, when a battery is used to supply power to a display device (100), a screen that has become dark due to a decrease in the light output intensity of a backlight unit (250) can be corrected to a bright screen using a DTM curve and a DC curve that are unrelated to power consumption.

This can improve the user's video viewing experience.

FIG. 12 is a diagram illustrating an example of adjusting the gain of a DTM curve and the gain of a DC curve when power is supplied to a display device through a battery and the illuminance measured through an illuminance sensor is above a certain illuminance according to an embodiment of the present disclosure.

The light sensor (not shown) may be provided in the display device (100) or may be provided separately from the display device (100).

When the light sensor is provided separately from the display device (100), the control unit (170) of the display device (100) can receive the light measured by the light sensor from the light sensor through the wireless communication unit (173).

Describes (a) of Fig. 12.

The control unit (170) can change the existing DTM curve (1010) to a new DTM curve (1210) with an upwardly adjusted gain when battery usage is detected and the illuminance measured by the illuminance sensor is above a certain level.

The control unit (170) can increase the gain of the DTM curve (1010) as battery usage is detected and the illuminance increases, thereby generating a new DTM curve (1210).

The storage unit (140) may store a lookup table that matches an illuminance value above a certain illuminance with a gain value of the DTM curve. The control unit (170) may obtain a gain of the DTM curve that matches the measured illuminance from the lookup table, and change the shape of the DTM curve according to the obtained gain.

Accordingly, even if the ambient illumination of the display device (100) increases, the brightness of the video signal can be adjusted upward, thereby improving the user's video viewing experience.

Meanwhile, after generating a new DTM curve (1210), the control unit (170) can change the existing DC curve (1110) to a new DC curve (1230) with increased gain to compensate for the image signal.

Accordingly, the contrast in the low-gray area may increase and the contrast in the dark area may decrease compared to the existing DC curve (1110).

FIG. 13 is a drawing illustrating a method for determining whether an embodiment of the present disclosure described in FIG. 8 is applied.

Referring to (a) of Fig. 13, the display unit (180) of the display device (100) displays an internal pattern received from a pattern generator in a central area (1310). A fixed external pattern may be provided in an area other than the central area (1310).

The pattern generator can output the internal pattern on the central area (1310) of the display unit (180) while changing the signal level of the internal pattern from a black level to a white level.

Referring to (b) of FIG. 13, a first curve (1331) showing a change in brightness according to a signal level when the display device (100) is powered from an AC power source (1300) and a second curve (1333) showing a change in brightness according to a signal level when the display device (100) is powered from a battery are shown.

That is, when the luminance is measured higher for the same signal level in the central region (1310) when the battery is used, it can be confirmed that the gain of the DTM curve is adjusted according to the embodiment of the present disclosure.

Also, referring to (b) of FIG. 13, a third curve (1335) is illustrated showing a change in brightness according to a signal level when the display device (100) is powered by a battery and the light sensor detects a certain level of light or higher.

That is, when battery usage is detected, the light sensor is above a certain level of illuminance, and the luminance measured in the central area (1310) is measured higher than the same signal level when only battery usage is detected, it can be confirmed that the gain of the DTM curve is adjusted according to the embodiment of the present disclosure.

The above-described present disclosure can be implemented as a computer-readable code on a medium in which a program is recorded. The computer-readable medium includes all kinds of recording devices in which data that can be read by a computer system is stored. Examples of the computer-readable medium include a hard disk drive (HDD), a solid state disk (SSD), a silicon disk drive (SDD), a ROM, a RAM, a CD-ROM, a magnetic tape, a floppy disk, an optical data storage device, and the like. In addition, the computer may include a control unit (170) of a display device (100). Therefore, the above detailed description should not be construed as limiting in all aspects and should be considered as illustrative.

Claims (15)

In display devices,
display panel;
A backlight unit that outputs light to the above display panel; and
When the display device is powered by a battery, a control unit is included that reduces the light output intensity of the backlight unit according to the remaining amount of the battery, adjusts the gain of the dynamic tone mapping curve and the gain of the dynamic contrast curve for the input image signal according to the reduction in the light output intensity, and outputs the output image signal generated according to the adjustment of each gain to the display panel.
Display device. In the first paragraph,
The above control unit
After adjusting the gain of the dynamic tone mapping curve for the input image signal according to the decrease in the above light output intensity, the gain of the dynamic contrast curve is adjusted.
Display device. In the second paragraph,
The above control unit
After increasing the gain of the above dynamic tone mapping curve, increase the gain of the above dynamic contrast curve.
Display device. In the second paragraph,
The above control unit
Adjusting the gain of the dynamic tone mapping curve so that the ratio of the input value and the output value of the input video signal exceeds 1 and has a value less than a preset value.
Display device. In paragraph 4,
The above control unit
Adjust the gain of the dynamic tone mapping curve to make the slope of the curve corresponding to the high-tonation area gentler.
Display device. In paragraph 4,
The above control unit
The gain of the dynamic contrast curve is adjusted so that the ratio of the output value to the input value in the low-grayscale area is less than 1, and the ratio of the output value to the input value in the high-grayscale area is greater than 1.
Display device. In the third paragraph,
The above control unit
When the illuminance measured by the illuminance sensor is above a certain illuminance, the gain of the dynamic tone mapping curve is further increased, and then the gain of the dynamic contrast curve is further increased.
Display device. In the first paragraph,
The above battery is provided separately from the above display device.
Display device. A method for operating a display device including a display panel and a backlight unit that outputs light to the display panel,
A step of reducing the light output intensity of the backlight unit according to the remaining power of the battery when the display device is powered by a battery;
A step of adjusting the gain of a dynamic tone mapping curve and the gain of a dynamic contrast curve for an input image signal according to a decrease in the above light output intensity; and
A step of outputting an output image signal generated according to the adjustment of each gain to the display panel is included.
How the display device operates. In Article 9,
The above adjustment steps are
A method comprising: adjusting a gain of a dynamic tone mapping curve for an input image signal according to a decrease in the light output intensity; and then adjusting a gain of the dynamic contrast curve.
How the display device operates. In Article 10,
The above adjustment steps are
A step of increasing the gain of the dynamic contrast curve after increasing the gain of the dynamic tone mapping curve.
How the display device operates. In Article 10,
The steps for adjusting the gain of the above dynamic tone mapping curve are:
A step of adjusting the gain of the dynamic tone mapping curve so that the ratio of the input value and the output value of the input image signal exceeds 1 and has a value less than a preset value.
How the display device operates. In Article 12,
The steps for adjusting the gain of the above dynamic tone mapping curve are:
A step of adjusting the gain of the dynamic tone mapping curve to make the slope of the curve of the portion corresponding to the high-gray area gentle.
How the display device operates. In Article 12,
The step of adjusting the gain of the above dynamic contrast curve is
A step of adjusting the gain of the dynamic contrast curve so that the ratio of the output value to the input value of the low-grayscale region is less than 1 and the ratio of the output value to the input value of the high-grayscale region is greater than 1.
How the display device operates. In Article 11,
If the illuminance measured by the illuminance sensor is greater than a certain illuminance, the method further includes a step of further increasing the gain of the dynamic tone mapping curve and then further increasing the gain of the dynamic contrast curve.
How the display device operates.

Images