KR102305951B1 - Image display apparatus - Google Patents

Abstract

The present invention relates to an image display device for a mobile terminal capable of reducing power consumption when driving a PWM display device in outdoor visibility mode, and when image data is input, image mode and grayscale are determined to determine the outdoor visibility of the image mode. mode, the low grayscale data drives the data line with the current intensity and pulse width used in the normal mode, and the high grayscale data drives the data line with the current intensity and pulse width of the outdoor visibility mode. reduce power consumption.

Description

Image display device {IMAGE DISPLAY APPARATUS}

The present invention relates to an image display device capable of reducing power consumption when driving a PWM display in an outdoor visibility mode.

The terminal may be divided into a mobile/portable terminal and a stationary terminal according to whether the terminal can be moved. Again, the mobile terminal can be divided into a handheld terminal and a vehicle mounted terminal depending on whether the user can carry it directly.

The functions of mobile terminals are diversifying. For example, there are functions for data and voice communication, photo and video shooting through a camera, voice recording, music file playback through a speaker system, and an image or video output to the display unit. Some terminals add an electronic game play function or perform a multimedia player function. In particular, recent mobile terminals can receive multicast signals that provide broadcast and visual content such as video or television programs.

Such a terminal is implemented in the form of a multimedia player equipped with complex functions such as, for example, taking pictures or videos, playing music or video files, playing games, and receiving broadcasts as functions are diversified. .

In order to support and increase the function of the terminal, it may be considered to improve the structural part and/or the software part of the terminal.

Recently, portable mobile devices are trying to improve outdoor visibility of displays. In order to improve outdoor visibility, a method of raising the display to the maximum luminance is usually used, but it has a disadvantage in that the battery consumption is large due to increased power consumption. For example, in the case of Samsung Galaxy Gear Fit, there is an outdoor mode, but it is limited to 5 minutes, which proves that it consumes a lot of power.

That is, in the case of a PWM-driven display that expresses grayscale by adjusting the length of the pulse width (PWM), the intensity of current must be increased in order to increase outdoor visibility. The reason is to increase the current strength because the PWM driving method cannot express high luminance for outdoor visibility due to the limitation of the time (time allocated to express one frame) that can increase the pulse length.

However, when the intensity of current is increased to increase outdoor visibility, power consumption is increased and battery consumption is large. Therefore, a method for reducing power consumption suitable for the PWM driving method is absolutely necessary.

An object of the present invention is to provide an image display device capable of reducing power consumption when a PWM display device is driven in an outdoor visibility mode, and a method for reducing power consumption thereof.

Another object of the present invention is to provide an image display device capable of driving a display device with different current intensities in a low gray scale and a high gray scale in an outdoor visibility mode, and a method for reducing power consumption thereof.

In order to achieve the above object, an image display device according to an embodiment of the present specification includes: a display panel including a plurality of pixels connected to a scan line and a data line; a scan driver for driving a scan line; a data driver for driving the data line; and a control unit configured to control the data driving unit to discriminate between low and high gray levels of image data in the outdoor visibility mode, and drive the data lines with different current strengths in the low and high gray levels.

The controller discriminates the image data into a low grayscale and a high grayscale based on the grayscale that produces the maximum brightness in the normal mode.

The controller controls the data line to be driven with the current intensity and pulse width of the low grayscale data in the normal mode, and the data line driven with the high grayscale data using the current intensity and pulse width in the outdoor visibility mode.

When the low grayscale data of the outdoor visibility mode is driven by the current and the pulse width of the normal mode, the controller may control the difference between the maximum brightness of the normal mode and the minimum brightness of the outdoor visibility mode to be 2 to 3 grayscales or less.

The controller reduces the number of grayscales by dividing M grayscales by a quantization coefficient (N) determined according to the brightness of external light (M/N) when expressing low grayscales in the outdoor visibility mode.

The control unit may include: an image determination unit configured to output a gray level determination signal by determining whether the image data is a low gray level or a high gray level based on the maximum brightness that can be generated in the normal mode; an image processing unit for converting image data to match the current intensity and pulse of the normal mode or the outdoor visibility mode according to the mode selection signal and the grayscale determination signal; a frame memory for storing the image data converted by the image processing unit and transferring the converted image data to the data driver; and a reset unit configured to output a reset signal to the frame memory according to the gray level determination signal and the mode selection signal output from the image determination unit.

In order to achieve the above object, a method for reducing power consumption of an image display apparatus according to an embodiment of the present specification includes: determining an image mode when image data is input; determining the gray level of the image data; and driving the data line with different current strengths for the determined low grayscale and high grayscale data when the image mode is the outdoor visibility mode.

A low grayscale and a high grayscale of the image data are determined based on the grayscale that produces the maximum brightness in the normal mode.

The driving of the data line may include: driving the data line with a current intensity and a pulse width using the low grayscale data in a normal mode; and driving the data line with the current intensity and pulse width of the high grayscale data in an outdoor visibility mode.

When the low grayscale data of the outdoor visibility mode is driven by the current and the pulse width of the normal mode, the difference between the maximum brightness of the normal mode and the minimum brightness of the outdoor visibility mode is controlled to be 2 to 3 grayscales or less.

The method may further include converting M grayscales into M/N grayscales when expressing low grayscales in the outdoor visibility mode. Here, N is a quantization coefficient determined according to the brightness of external light.

The image display device according to the present invention operates with the current intensity and pulse width used in the normal mode for low grayscale data in the outdoor visibility mode, and generates data lines with the current intensity and pulse width of the outdoor visibility mode for high grayscale data. Power consumption in the outdoor visibility mode can be reduced by driving, and in particular, when expressing low grayscales in visibility mode, M grayscales are reduced (quantized) to M/N grayscales, thereby further reducing power consumption. .

1 is a block diagram of a mobile terminal including an image display device according to the present invention;
2 is a graph showing the current intensity of a PWM pulse driving a display panel in a normal mode and an outdoor visibility mode;
3 is a block diagram of an image display device according to a first embodiment of the present invention;
4 is a block diagram of an image display device according to a second embodiment of the present invention;
5 is a flowchart illustrating a method of reducing power consumption when an image display device operates in a visibility mode according to an embodiment of the present invention.
6 and 7 are diagrams illustrating a concept of driving a data line using two or more types of current intensities in an outdoor visibility mode.
8 is an embodiment in which grayscale quantization is performed at a low grayscale in an outdoor visibility mode;
9 is an exemplary diagram of driving pulses of one frame with different current strengths in a low gray scale in an outdoor visibility mode;

Hereinafter, the embodiments disclosed herein will be described in detail with reference to the accompanying drawings, but identical or similar components are given the same and similar reference numerals, and overlapping descriptions thereof will be omitted. The suffixes "module" and "part" for the components used in the following description are given or mixed in consideration of only the ease of writing the specification, and do not have a meaning or role distinct from each other by themselves. In addition, the accompanying drawings are only for easy understanding of the embodiments disclosed in the present specification, and the technical spirit disclosed herein is not limited by the accompanying drawings, and all changes included in the spirit and scope of the present invention , should be understood to include equivalents or substitutes.

The mobile terminal described in this specification includes a mobile phone, a smart phone, a laptop computer, a digital broadcasting terminal, a personal digital assistant (PDA), a portable multimedia player (PMP), a navigation system, and a slate PC. , tablet PCs, ultrabooks, wearable devices, for example, watch-type terminals (smartwatch), glass-type terminals (smart glass), HMD (head mounted display), etc. may be included. have.

However, it will be readily apparent to those skilled in the art that the configuration according to the embodiment described in this specification may be applied to a fixed terminal such as a digital TV, a desktop computer, and a digital signage, except when applicable only to a mobile terminal. will be.

1 is a block diagram illustrating a mobile terminal related to the present invention.

The mobile terminal 100 includes a wireless communication unit 110 , an input unit 120 , a sensing unit 140 , an output unit 150 , an interface unit 160 , a memory 170 , a control unit 180 , and a power supply unit 190 . and the like. Since the components shown in FIG. 1 are not essential for implementing the mobile terminal, the mobile terminal described in this specification may have more or fewer components than those listed above.

The wireless communication unit 110 is one that enables wireless communication between the mobile terminal 100 and a wireless communication system, between the mobile terminal 100 and another mobile terminal 100, or between the mobile terminal 100 and an external server. It may include more than one module.

The wireless communication unit 110 may include at least one of a broadcast reception module 111 , a mobile communication module 112 , a wireless Internet module 113 , a short-range communication module 114 , and a location information module 115 .

The input unit 120 includes a camera 121 or an image input unit for inputting an image signal, a microphone 122 or an audio input unit for inputting an audio signal, and a user input unit 123 for receiving information from a user, for example, , a touch key, a push key, etc.). The voice data or image data collected by the input unit 120 may be analyzed and processed as a user's control command.

The sensing unit 140 may include one or more sensors for sensing at least one of information in the mobile terminal, surrounding environment information surrounding the mobile terminal, and user information. For example, the sensing unit 140 may include a proximity sensor 141, an illumination sensor 142, an illumination sensor, a touch sensor, an acceleration sensor, a magnetic sensor, and gravity. Sensor (G-sensor), gyroscope sensor, motion sensor, RGB sensor, infrared sensor (IR sensor: infrared sensor), fingerprint sensor (finger scan sensor), ultrasonic sensor , optical sensors (eg, cameras (see 121)), microphones (see 122), battery gauges, environmental sensors (eg, barometers, hygrometers, thermometers, radiation detection sensors, It may include at least one of a thermal sensor, a gas sensor, etc.) and a chemical sensor (eg, an electronic nose, a healthcare sensor, a biometric sensor, etc.). Meanwhile, the mobile terminal disclosed in the present specification may combine and utilize information sensed by at least two or more of these sensors.

The output unit 150 is for generating an output related to visual, auditory or tactile sense, and includes at least one of a display unit 151 , a sound output unit 152 , a haptip module 153 , and an optical output unit 154 . can do. The display unit 151 may implement a touch screen by forming a layer structure with the touch sensor or being formed integrally with the touch sensor.

The interface unit 160 serves as a passage with various types of external devices connected to the mobile terminal 100 . This interface unit 160, a wired / wireless headset port (port), an external charger port (port), a wired / wireless data port (port), a memory card (memory card) port, for connecting a device equipped with an identification module It may include at least one of a port, an audio input/output (I/O) port, a video input/output (I/O) port, and an earphone port.

The memory 170 may store data supporting various functions of the mobile terminal 100 , a plurality of application programs or applications, data for operation of the mobile terminal 100 , and commands.

In addition to the operation related to the application program, the controller 180 generally controls the overall operation of the mobile terminal 100 . The controller 180 may provide or process appropriate information or functions to the user by processing signals, data, information, etc. input or output through the above-described components or by driving an application program stored in the memory 170 .

Also, in order to drive an application program stored in the memory 170 , the controller 180 may control at least some of the components discussed with reference to FIG. 1 or operate at least two or more of the components in combination with each other.

The power supply unit 190 receives external power and internal power under the control of the control unit 180 and supplies power to each component included in the mobile terminal 100 . The power supply 190 includes a battery, and the battery may be a built-in battery or a replaceable battery.

Hereinafter, before looking at various embodiments implemented through the mobile terminal 100 as described above, the above-listed components will be described in more detail with reference to FIG. 1 .

First, referring to the wireless communication unit 110 , the broadcast reception module 111 of the wireless communication unit 110 receives a broadcast signal and/or broadcast-related information from an external broadcast management server through a broadcast channel. The broadcast channel may include a satellite channel and a terrestrial channel. Two or more of the broadcast reception modules may be provided to the mobile terminal 100 for simultaneous broadcast reception or broadcast channel switching for at least two broadcast channels.

The broadcast management server may mean a server that generates and transmits a broadcast signal and/or broadcast-related information or a server that receives and transmits a previously generated broadcast signal and/or broadcast-related information to a terminal. The broadcast signal may include a TV broadcast signal, a radio broadcast signal, and a data broadcast signal, as well as a TV broadcast signal or a broadcast signal in which a data broadcast signal is combined with a radio broadcast signal.

The mobile communication module 112 includes technical standards or communication methods for mobile communication (eg, Global System for Mobile communication (GSM), Code Division Multi Access (CDMA), Code Division Multi Access 2000 (CDMA2000), EV -DO (Enhanced Voice-Data Optimized or Enhanced Voice-Data Only), WCDMA (Wideband CDMA), HSDPA (High Speed Downlink Packet Access), HSUPA (High Speed Uplink Packet Access), LTE (Long Term Evolution), LTE-A (Long Term Evolution-Advanced, etc.) transmits/receives a radio signal to and from at least one of a base station, an external terminal, and a server on a mobile communication network constructed according to (Long Term Evolution-Advanced).

The wireless signal may include various types of data according to transmission/reception of a voice call signal, a video call signal, or a text/multimedia message.

The wireless Internet module 113 refers to a module for wireless Internet access, and may be built-in or external to the mobile terminal 100 . The wireless Internet module 113 is configured to transmit and receive wireless signals in a communication network according to wireless Internet technologies.

Short-range communication module 114 is for short-range communication, Bluetooth™, RFID (Radio Frequency Identification), infrared communication (Infrared Data Association; IrDA), UWB (Ultra Wideband), ZigBee, NFC At least one of (Near Field Communication), Wireless-Fidelity (Wi-Fi), Wi-Fi Direct, and Wireless Universal Serial Bus (USB) technologies may be used to support short-range communication.

Here, the other mobile terminal 100 is a wearable device capable of exchanging data (or interworking) with the mobile terminal 100 according to the present invention, for example, a smart watch, smart glasses. (smart glass), HMD (head mounted display)). The short-range communication module 114 may detect (or recognize) a wearable device capable of communicating with the mobile terminal 100 in the vicinity of the mobile terminal 100 . Furthermore, when the detected wearable device is a device authenticated to communicate with the mobile terminal 100 according to the present invention, the controller 180 transmits at least a portion of data processed by the mobile terminal 100 to the short-range communication module ( 114) to transmit to the wearable device. Accordingly, the user of the wearable device may use data processed by the mobile terminal 100 through the wearable device.

The location information module 115 is a module for acquiring a location (or current location) of a mobile terminal, and a representative example thereof includes a Global Positioning System (GPS) module or a Wireless Fidelity (WiFi) module. For example, if the mobile terminal utilizes a GPS module, it can acquire the location of the mobile terminal by using a signal transmitted from a GPS satellite. As another example, if the mobile terminal utilizes the Wi-Fi module, the location of the mobile terminal may be obtained based on information of the Wi-Fi module and a wireless access point (AP) that transmits or receives a wireless signal. If necessary, the location information module 115 may perform any function of the other modules of the wireless communication unit 110 to obtain data on the location of the mobile terminal as a substitute or additionally. The location information module 115 is a module used to obtain the location (or current location) of the mobile terminal, and is not limited to a module that directly calculates or obtains the location of the mobile terminal.

Next, the input unit 120 is for input of image information (or signal), audio information (or signal), data, or information input from a user. Alternatively, a plurality of cameras 121 may be provided. The camera 121 processes an image frame such as a still image or a moving image obtained by an image sensor in a video call mode or a photographing mode. The processed image frame may be displayed on the display unit 151 or stored in the memory 170 .

The microphone 122 processes an external sound signal as electrical voice data. The processed voice data may be utilized in various ways according to a function (or a running application program) being performed by the mobile terminal 100 . Meanwhile, various noise removal algorithms for removing noise generated in the process of receiving an external sound signal may be implemented in the microphone 122 .

The user input unit 123 is for receiving information from a user, and when information is input through the user input unit 123 , the controller 180 may control the operation of the mobile terminal 100 to correspond to the input information. . The user input unit 123 is a mechanical input means (or a mechanical key, for example, a button located on the front, rear or side of the mobile terminal 100, a dome switch, a jog wheel, jog switch, etc.) and a touch input means. As an example, the touch input means consists of a virtual key, a soft key, or a visual key displayed on the touch screen through software processing, or a part other than the touch screen. It may be made of a touch key (touch key) disposed on the. On the other hand, the virtual key or the visual key, it is possible to be displayed on the touch screen while having various forms, for example, graphics (graphic), text (text), icon (icon), video (video) or these can be made by a combination of

Meanwhile, the sensing unit 140 senses at least one of information in the mobile terminal, surrounding environment information surrounding the mobile terminal, and user information, and generates a sensing signal corresponding thereto. The controller 180 may control the driving or operation of the mobile terminal 100 or perform data processing, functions, or operations related to an application program installed in the mobile terminal 100 based on the sensing signal. Representative sensors among various sensors that may be included in the sensing unit 140 will be described in more detail.

First, the proximity sensor 141 refers to a sensor that detects the presence or absence of an object approaching a predetermined detection surface or an object existing in the vicinity without mechanical contact using the force of an electromagnetic field or infrared rays.

On the other hand, for convenience of description, the act of approaching an object on the touch screen without contacting it so that the object is recognized that it is located on the touch screen is called “proximity touch”, and the touch The act of actually touching an object on the screen is called "contact touch". The position where the object is touched in proximity on the touch screen means a position where the object is perpendicular to the touch screen when the object is touched in proximity. The proximity sensor 141 may detect a proximity touch and a proximity touch pattern (eg, proximity touch distance, proximity touch direction, proximity touch speed, proximity touch time, proximity touch position, proximity touch movement state, etc.) have. Meanwhile, the controller 180 processes data (or information) corresponding to the proximity touch operation and the proximity touch pattern sensed through the proximity sensor 141 as described above, and further, provides visual information corresponding to the processed data. It can be printed on the touch screen. Furthermore, the controller 180 may control the mobile terminal 100 to process different operations or data (or information) according to whether a touch to the same point on the touch screen is a proximity touch or a contact touch. .

The touch sensor senses a touch (or touch input) applied to the touch screen (or the display unit 151) using at least one of various touch methods such as a resistive film method, a capacitive method, an infrared method, an ultrasonic method, and a magnetic field method. do.

As an example, the touch sensor may be configured to convert a change in pressure applied to a specific part of the touch screen or a change in capacitance occurring in a specific part of the touch screen into an electrical input signal. The touch sensor may be configured to detect a position, an area, a pressure at the time of a touch, an electrostatic capacitance at the time of a touch, etc. in which a touch object applying a touch on the touch screen is touched on the touch sensor. Here, the touch object is an object that applies a touch to the touch sensor, and may be, for example, a finger, a touch pen or a stylus pen, a pointer, or the like.

As such, when there is a touch input to the touch sensor, a signal(s) corresponding thereto is sent to the touch controller. The touch controller processes the signal(s) and then transmits corresponding data to the controller 180 . Accordingly, the controller 180 can know which area of the display unit 151 has been touched, and the like. Here, the touch controller may be a component separate from the controller 180 , or may be the controller 180 itself.

Meanwhile, the controller 180 may perform different controls or may perform the same control according to the type of the touch object that touches the touch screen (or a touch key provided in addition to the touch screen). Whether to perform different controls or the same control according to the type of the touch object may be determined according to the current operating state of the mobile terminal 100 or a running application program.

On the other hand, the above-described touch sensor and proximity sensor independently or in combination, a short (or tap) touch on the touch screen (short touch), long touch (long touch), multi touch (multi touch), drag touch (drag touch) ), flick touch, pinch-in touch, pinch-out touch, swype touch, hovering touch, etc. It can sense touch.

The ultrasonic sensor may recognize location information of a sensing target by using ultrasonic waves. Meanwhile, the controller 180 may calculate the position of the wave source through information sensed by the optical sensor and the plurality of ultrasonic sensors. The position of the wave source may be calculated using the property that light is much faster than ultrasonic waves, that is, the time for light to reach the optical sensor is much faster than the time for ultrasonic waves to reach the ultrasonic sensor. More specifically, the position of the wave source may be calculated using a time difference between the time that the ultrasonic wave arrives using light as the reference signal.

On the other hand, the camera 121 as seen in the configuration of the input unit 120 includes at least one of a camera sensor (eg, CCD, CMOS, etc.), a photo sensor (or an image sensor), and a laser sensor.

The camera 121 and the laser sensor may be combined with each other to detect a touch of a sensing target for a 3D stereoscopic image. The photo sensor may be stacked on the display device, and the photo sensor is configured to scan the movement of the sensing target close to the touch screen. More specifically, the photo sensor mounts photo diodes and transistors (TRs) in rows/columns and scans the contents placed on the photo sensor using electrical signals that change according to the amount of light applied to the photo diodes. That is, the photo sensor calculates the coordinates of the sensing target according to the amount of change in light, and through this, location information of the sensing target can be obtained.

The display unit 151 displays (outputs) information processed by the mobile terminal 100 . For example, the display unit 151 may display execution screen information of an application program driven in the mobile terminal 100 or UI (User Interface) and GUI (Graphic User Interface) information according to the execution screen information. .

Also, the display unit 151 may be configured as a stereoscopic display unit for displaying a stereoscopic image.

The sound output unit 152 may output audio data received from the wireless communication unit 110 or stored in the memory 170 in a call signal reception, a call mode or a recording mode, a voice recognition mode, a broadcast reception mode, and the like. The sound output unit 152 also outputs a sound signal related to a function (eg, a call signal reception sound, a message reception sound, etc.) performed in the mobile terminal 100 . The sound output unit 152 may include a receiver, a speaker, a buzzer, and the like.

The haptic module 153 generates various tactile effects that the user can feel. A representative example of the tactile effect generated by the haptic module 153 may be vibration. The intensity and pattern of vibration generated by the haptic module 153 may be controlled by a user's selection or setting of the controller. For example, the haptic module 153 may synthesize and output different vibrations or output them sequentially.

In addition to vibration, the haptic module 153 is configured to respond to stimuli such as a pin arrangement that moves vertically with respect to the contact skin surface, a jet force or suction force of air through a nozzle or an inlet, a brush against the skin surface, contact of an electrode, an electrostatic force, etc. Various tactile effects can be generated, such as an effect caused by heat absorption and an effect by reproducing a feeling of cold and heat using an element capable of absorbing heat or generating heat.

The light output unit 154 outputs a signal for notifying the occurrence of an event by using the light of the light source of the mobile terminal 100 . Examples of the event generated in the mobile terminal 100 may be message reception, call signal reception, missed call, alarm, schedule notification, email reception, information reception through an application, and the like.

The interface unit 160 serves as a passage with all external devices connected to the mobile terminal 100 . The interface unit 160 receives data from an external device, receives power and transmits it to each component inside the mobile terminal 100 , or transmits data inside the mobile terminal 100 to an external device. For example, a wired/wireless headset port, an external charger port, a wired/wireless data port, a memory card port, a port for connecting a device equipped with an identification module (port), an audio I/O (Input/Output) port, a video I/O (Input/Output) port, an earphone port, etc. may be included in the interface unit 160 .

The memory 170 may store a program for the operation of the controller 180 , and may temporarily store input/output data (eg, a phone book, a message, a still image, a moving image, etc.). The memory 170 may store data related to vibrations and sounds of various patterns output when a touch input on the touch screen is input.

The memory 170 is a flash memory type, a hard disk type, a solid state disk type (SSD), a silicon disk drive type (SDD), and a multimedia card micro type. ), a card-type memory (eg, SD or XD memory), and a random access memory (RAM), which may include at least one type of storage medium. The mobile terminal 100 may be operated in relation to a web storage that performs a storage function of the memory 170 on the Internet.

The power supply unit 190 receives external power and internal power under the control of the control unit 180 to supply power necessary for the operation of each component. The power supply unit 190 includes a battery, and the battery may be a built-in battery configured to be rechargeable, and may be detachably coupled to the terminal body for charging or the like. In addition, the power supply unit 190 may include a connection port, and the connection port may be configured as an example of the interface 160 to which an external charger that supplies power for charging the battery is electrically connected.

Hereinafter, a case in which the display unit 151 is a light emitting diode (OLED) display device will be described with reference to FIG. 1 .

2 is a graph showing the current intensity of a PWM pulse driving a display panel in a normal mode and an outdoor visibility mode.

Referring to FIG. 2 , in the normal mode, increasing the pulse length is limited due to time constraints. Therefore, in the case of a display that expresses grayscale by adjusting the pulse width (PWM) length, in order to increase outdoor visibility, that is, in the outdoor visibility mode, the intensity of current needs to be increased. However, there is a disadvantage in that, if the intensity of the current is increased, power consumption is increased, and thus battery consumption is increased.

Accordingly, the present invention proposes a method of driving each data line of a display panel using different magnitudes of current intensities in order to reduce power consumption in the outdoor visibility mode.

In one embodiment, the present invention drives the data line with the current intensity and pulse width used in the normal mode for low grayscale data in the outdoor visibility mode, and uses the current intensity and pulse width for the outdoor visibility mode for high grayscale data. can drive

In another embodiment, the present invention provides the maximum luminance (maximum brightness) of the normal mode and the minimum of the outdoor visibility mode when the low grayscale (using high current) data in the outdoor visibility mode is driven with current and pulses in the normal mode (using low current). Drive so that the difference in luminance (minimum brightness) is less than 2 or 3 gradations.

In another embodiment, the present invention may drive a different current strength for each data line according to image data in order to reduce power consumption in the PWM driving method.

In another embodiment, the present invention may adjust the number of grayscale expressions in order to reduce power consumption when expressing low grayscales in an outdoor visibility mode in a PWM driving method.

3 is a first embodiment of an image display device to which the display unit 151 according to an embodiment of the present invention is applied. The image display device may be a light emitting diode (LED) or an OLED display device.

As shown in FIG. 3 , the image display device according to the first embodiment of the present invention includes a controller 210 , a data driver 220 , a scan driver 230 , and a display panel 240 .

The controller 210 converts the input image data (RGB data) according to the image mode (normal mode or outdoor visibility mode) and the image grayscale (low grayscale or high grayscale) and provides it to the data driver 220 . The control unit 210 is the same as the control unit 180 of FIG. 1 except that the number is different.

The data driver 220 receives the image data converted by the controller 210 and generates a data signal corresponding thereto, and the data signal generated by the data driver 500a is synchronized with the scan signal through data lines D1 to D1 to Dm) and transmitted to each pixel 110a of the display panel 240 .

The scan driver 400a generates a scan signal, and the generated scan signal is sequentially supplied to each of the scan lines S1 to Sn.

The display panel 240 includes a plurality of pixels 110a connected to scan lines S1 to Sn and data lines D1 to Dm. Here, one pixel 110a may include at least two sub-pixels each having an organic light emitting diode and emitting light of different colors. The display panel 240 displays an image in response to externally supplied power Vdd and Vss, a scan signal from the scan driver 400a, and a data signal from the data driver 500a.

The control unit 210 may include an image processing unit 20 , an image determination unit 21 , a reset unit 22 , and a frame memory 23 .

The image processing unit 20 converts the image data (RGB data) according to the current intensity and pulse of the normal mode or the outdoor visibility mode according to the mode selection signal MDC. In addition, the image processing unit 20 outputs the current intensity and pulse used in the normal mode for low grayscale data according to the grayscale determination signal GS in the outdoor visibility mode, and the current intensity of the outdoor visibility mode for high grayscale data. and output a pulse. The mode selection signal MS may be automatically generated according to a user's manipulation (touch or key input) or the intensity of external light through an optical sensor.

The image determination unit 21 determines whether the image data is a low gray level or a high gray level based on the maximum brightness (MAXnormal) that can be produced in the normal mode, and transmits the gray level determination signal GS to the image processing unit 400 .

The frame memory 22 receives and stores image data from the image processing unit 20 , and transmits the stored image data to the data driver 220 . The frame memory 22 stores image data in units of one frame.

The reset unit 23 outputs a reset signal to the frame memory 22 to delete image data stored in the frame memory 22 and to store new image data in the frame memory 22 again. The reset signal is generated according to the gray level determination signal GS and the mode selection signal MS output to the image determination unit 21 .

4 is a block diagram of an image display device to which the display unit 151 according to the second embodiment of the present invention is applied.

As shown in FIG. 4 , the image display device according to the second embodiment of the present invention includes a control unit 310 , a data driving unit 320 , a scan driving unit 330 , and a display panel 340 , and the control unit 310 . ) and the operation of the data driver 320 are the same as in the first embodiment.

The mode selection signal MS and the gray level determination signal GS are output together with the input image data (RGB data) to the data driver 320, and the data driver 320 provides the mode selection signal MS and the gray level determination signal ( GS), image data corresponding to the current intensity and pulse of the normal mode or outdoor visibility mode is output to the display panel 340 .

A method for saving power when operating in visibility mode in the LED display device according to an embodiment of the present invention configured as described above will be described.

5 is a flowchart illustrating a method of reducing power consumption when an image display device operates in a visibility mode according to the present invention.

3 and 5, when image data (RGB data) is input (S100), the controller 210 or 180 determines whether the image mode is a normal mode or an outdoor visibility mode (S110, S120). The image mode may be set by a user input or may be automatically determined by comparing an intensity of external light measured through an optical sensor with a preset intensity of light.

As a result of the determination, in the normal mode, the control unit 210 converts the image data (RGB data) into image data having the current strength and pulse width of the normal mode, and outputs it to the data driver 220 to drive the data lines D1 to Dm. do (S140).

On the other hand, in the outdoor visibility mode, the controller 210 checks whether the image data (RGB data) is a low grayscale or a high grayscale (S130). The criterion for the determination is the maximum brightness (high gradation in the normal mode) that can be produced in the normal mode.

If the check result is high grayscale, the image data (RGB data) is converted into image data having the current intensity and pulse width of the outdoor visibility mode and output to the data driver 220 to drive the data lines D1 to Dm (S150). In addition, if the check result is a low gray scale, the controller 210 converts the image data (RGB data) into image data having the current intensity and pulse width of the normal mode, and outputs the converted image data to the data driver 220 to generate the data lines D1 to Dm. drive (S140).

Also, according to the present invention, the data lines can be driven with different current strengths by converting the image data only in the outdoor visibility mode without converting the image data in the normal mode.

Accordingly, in the present invention, outdoor visibility is achieved by driving the data line with the current intensity and pulse width of the outdoor visibility mode in case of high grayscale data and driving the data line with the current intensity and pulse width used in the normal mode for low grayscale data in the outdoor visibility mode. Power consumption in mode can be reduced.

6 and 7 are diagrams illustrating a concept of driving a data line using two or more current intensities in an outdoor visibility mode.

As shown in FIG. 6 , even with a combination of the current intensity and the pulse width used in the normal mode (general gray scale expression), the intensity of some low gray scale light in the outdoor visibility mode in which the current intensity is increased may be generated. That is, according to the present invention, the low grayscale of the outdoor visibility mode can be replaced with the high grayscale of the normal mode. At this time, as shown in FIG. 7 , the controller 210 compares whether the grayscale of the image data in the outdoor visibility mode is greater than or less than the maximum brightness (maximum grayscale) that can be generated in the normal mode, and compares the low grayscale in the outdoor visibility mode. or high gradation is determined.

As a result of the determination, the controller 210 drives the data line by using the current intensity and pulse used in the normal mode when the low grayscale data is in the outdoor visibility mode, and using the current intensity and pulse of the outdoor visibility mode when the high grayscale data is used. can do.

In addition, the control unit 210 drives the difference between the maximum luminance (maximum brightness or high gradation) in the normal mode and the minimum luminance (minimum brightness or low gradation) in the outdoor visibility mode to be 2 to 3 gradations or less, so that natural gradation display can be achieved. Control.

In general, a display has a contrast ratio of 100:1 in the outdoors, and the ability to distinguish low gradations in the outdoors is remarkably poor. This means that the 255 grayscale representation of a general display is unnecessary outdoors.

Accordingly, the present invention proposes a method for reducing power consumption by reducing (quantizing) M grayscales to M/N grayscales when expressing low grayscales in the outdoor visibility mode.

8 is an exemplary embodiment in which grayscale quantization is performed at a low grayscale in an outdoor visibility mode.

As shown in FIG. 8 , the controller 210 drives the data line with the current intensity and pulse width used in the normal mode until the gray level (0 to 5) based on the gray level (6) in the visibility mode, and thereafter The data line is driven by the current strength and pulse used in outdoor visibility mode. In this case, the controller 210 automatically loads the value of the quantization coefficient N from a lockup table (not shown), thereby reducing the number of grayscales to be displayed in the low grayscale of the outdoor visibility mode. Here, N is a quantization coefficient determined according to the brightness of external light.

For example, when the quantization coefficient N=2, the controller 210 quantizes (converts) six grayscales into three grayscales (M/N=2). That is, 6 grayscale (0-5) data is converted into 3 grayscale (0,2,4) data, and grayscale (1,3,5) data that cannot be expressed is processed as a floor.

Accordingly, according to the present invention, power consumption can be further reduced by reducing (quantizing) M grayscales to M/N grayscales when expressing low grayscales in the outdoor visibility mode.

In general, if the size of the current (current value) and the area of the turn-on section created by the pulse width are the same, the LED can emit the same amount of light even if the current size and pulse width are different. In view of these characteristics, the present invention expresses one data (one frame) as n different signals capable of emitting the same amount of light in the low grayscale of the outdoor visibility mode, thereby reducing power consumption by driving different current strengths for each data line. can

9 is an exemplary diagram of driving pulses of one frame with different current strengths in a low gray scale in an outdoor visibility mode.

As shown in FIG. 9 , the image processing unit 20 in the control unit 210 changes a pulse of one frame into first to third sub-pulses (Frame 1/3, Frame 2/3, Frame 3/3). The first to third sub-pulses have the same area (pulse amplitude * pulse width), but have different heights and widths, and output the converted first to third sub-pulses as pulses of one frame. can do.

As described above, according to the present invention, in the outdoor visibility mode, the data line is driven with the current intensity and pulse width of the outdoor visibility mode when the low grayscale data is used in the normal mode, and the data line is driven with the high grayscale data. By doing so, power consumption in the outdoor visibility mode can be reduced, and in particular, there is an advantage in that power consumption can be further reduced by reducing (quantizing) M grayscales to M/N grayscales when expressing low grayscales in the visibility mode.

The present invention described above can be implemented as 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 readable by a computer system is stored. Examples of computer-readable media include Hard Disk Drive (HDD), Solid State Disk (SSD), Silicon Disk Drive (SDD), ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage device, etc. There is also a carrier wave (eg, transmission over the Internet) that is implemented in the form of. In addition, the computer may include the control unit 180 of the terminal. Accordingly, the above detailed description should not be construed as restrictive in all respects but as exemplary. The scope of the present invention should be determined by a reasonable interpretation of the appended claims, and all modifications within the equivalent scope of the present invention are included in the scope of the present invention.

20: image processing unit 21: image determination unit
22: frame memory 23: reset unit
210, 310: control unit 220, 320: data driver
230: scan driver 230, 330: scan driver
240, 340: pixel panel

Claims (18)

a display panel including a plurality of pixels connected to a scan line and a data line;
a scan driver for driving the scan line;
a data driver for driving the data line; and
a control unit for discriminating the low gray level and the high gray level of image data in the outdoor visibility mode, and controlling the data driving unit to drive the data line with different current intensities in the low gray level and the high gray level;
The control unit controls the data line to be driven with a current intensity and a pulse width using low grayscale data in a normal mode,
The image display device according to claim 1, wherein the high grayscale data is controlled to drive the data line with the current intensity and pulse width of the outdoor visibility mode. The method of claim 1 , wherein the display panel comprises:
A video display device, characterized in that the LED or OLED display device. According to claim 1, wherein the control unit
The image display apparatus according to claim 1, wherein the image data is divided into a low gradation and a high gradation based on the gradation that produces the maximum brightness in the normal mode. delete According to claim 1, wherein the control unit
When the low grayscale data of the outdoor visibility mode is driven by the current and pulse width of the normal mode, the difference between the maximum brightness in the normal mode and the minimum brightness in the outdoor visibility mode is controlled to be less than 2 to 3 grayscales. Device. According to claim 1, wherein the control unit
An image display device characterized in that the M gray scales are converted into M/N gray scales when low gray scales are expressed in the outdoor visibility mode. Here, N is a quantization coefficient determined according to the brightness of external light. The method of claim 6, wherein the control unit
The image display apparatus according to claim 1, wherein the remaining unconverted grayscales among the M grayscales are expressed by discarding. According to claim 1, wherein the control unit
an image determination unit configured to output a gray level determination signal by determining whether image data is a low gray level or a high gray level based on the maximum brightness available in the normal mode;
an image processing unit converting the image data to match the current intensity and pulse of the normal mode or the outdoor visibility mode according to the mode selection signal and the grayscale determination signal;
a frame memory for storing the image data converted by the image processing unit and transferring the converted image data to the data driver; and
and a reset unit outputting a reset signal to the frame memory according to the gray level determination signal and the mode selection signal output from the image determination unit. The method of claim 8, wherein the mode selection signal is
An image display device, characterized in that it is generated according to a user's input or is automatically generated according to the intensity of external light through an optical sensor. The method of claim 8, wherein the image processing unit
and processing the image data by replacing the low gradation of the outdoor visibility mode with the high gradation of the normal mode according to the mode selection signal and the gradation determination signal. delete delete delete delete delete delete delete delete

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