KR20160047624A - Display Device and Driving Method thereof - Google Patents

Abstract

The present invention relates to a display device and a method for driving the same, which can improve reliability through prevention of degradation of an element, can overcome a problem attributable to heat generation, can improve an ambient contrast ratio, and can reduce power consumption. The present invention relates to a display device comprising a panel, a sight detection unit, and a control unit. The panel displays an image. The sight detection unit detects a position of a line of sight of a user. The control unit operates in conjunction with the sight detection unit, and varies brightness of the panel in response to whether the user stares at the panel.

Description

DISPLAY DEVICE AND DRIVING METHOD THEREOF

The present invention relates to a display device and a driving method thereof.

As the information technology is developed, the market of display devices, which is a connection medium between users and information, is getting larger. Accordingly, a flat panel display (FPD) such as a liquid crystal display (LCD), an organic light emitting diode (OLED) display and a plasma liquid crystal display (PDP) ) Have been increasing. Among them, liquid crystal display devices capable of realizing high resolution and capable of not only miniaturization but also enlargement are widely used.

Some of the above-described display devices, for example, a liquid crystal display device and an organic light emitting display device, include a display panel including a plurality of sub-pixels arranged in a matrix form and a driver for driving the display panel. The driving unit includes a scan driver for supplying a scan signal (or a gate signal) to the display panel, and a data driver for supplying a data signal to the display panel.

When a scan signal, a data signal, or the like is supplied to the subpixels arranged in a matrix form, the selected subpixel emits light so that an image can be displayed.

The display device is implemented in various products such as a television, a mobile device (e.g., a smart phone), a wearable display device (e.g., a smart watch), a vehicle display device (e.g., navigation device) When the display device is implemented as a display device for user convenience, it is necessary to improve the daytime visibility in order to increase the discrimination power of the user. However, in the display device proposed in the past, only a simple function of improving daytime visibility by using only illumination information is proposed, and improvement thereof is required.

The present invention for solving the above-mentioned problems of the background art improves the reliability by preventing deterioration of devices, solves the problem of heat generation, increases the outdoor environment contrast ratio, and reduces power consumption.

The present invention relates to a display apparatus including a panel, a visual field sensing unit, and a control unit. The panel displays the image. The visual field sensing unit senses the position where the user's eyes stay. The control unit interlocks with the visual field sensing unit and varies the brightness of the panel in accordance with whether the user gazes at the panel.

The controller can increase the brightness of the panel when the user stares at the panel, and lower the brightness of the panel when the user does not gaze at the panel.

The control unit may increase the brightness of the light emitting diodes when the user gazes at the panel in a high illuminance state.

The control unit may vary the duty ratio of the current or pulse width signal supplied to the light emitting diodes when the user gazes at the panel in a high illuminance state.

The controller may further include a roughness detecting unit for detecting roughness, and the controller may change the brightness of the panel after deriving an appropriate brightness according to the roughness.

In another aspect, the invention provides a method comprising: detecting whether a user is staring at a panel; And varying the brightness of the panel in response to whether or not the user gazes at the panel.

The step of varying the brightness may vary the duty ratio of the current supplied to the light emitting diodes or the pulse width signal to vary the brightness of the panel when the user gazes at the panel.

The present invention can increase, maintain or decrease the brightness (or brightness) in response to the illuminance and the user's gaze, thereby increasing the outdoor environment contrast ratio and reducing power consumption. In addition, since the brightness (or brightness) is controlled in accordance with the illuminance and the user's gaze, the present invention can improve the reliability by preventing deterioration of the device and solve the problem of heat generation.

1 is a block diagram schematically showing a liquid crystal display device according to a first embodiment of the present invention;
2 is a circuit configuration diagram of the subpixel shown in FIG.
3 is a view showing an example of a liquid crystal display device implemented by a vehicle display device according to the first embodiment of the present invention.
4 is a diagram for explaining a relationship between a temperature rise and a light emission efficiency.
5 is a flow chart illustrating a method of adjusting brightness of an apparatus according to a first embodiment of the present invention.
FIG. 6 is a view for helping understanding of the description of FIG. 5; FIG.
FIG. 7 is a view showing a change in current with or without brightness control; FIG.
8 is a diagram showing a configuration example of a backlight control signal according to a change in current of FIG. 7;
9 is a flowchart illustrating a method of adjusting brightness of an apparatus according to a second embodiment of the present invention.
10 is a view showing a simulation result of brightness versus outdoor environment contrast ratio.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The display device described below is implemented by a liquid crystal display device, an organic light emitting display device, or the like. However, it should be understood that a liquid crystal display device will be described below as an example of the embodiment.

≪ Embodiment 1 >

FIG. 1 is a block diagram schematically showing a liquid crystal display according to a first embodiment of the present invention, and FIG. 2 is a circuit configuration diagram of the subpixel shown in FIG.

1 and 2, the LCD includes a roughness sensing unit 120, a visual field sensing unit 125, a timing control unit 130, a gate driving unit 140, a data driving unit 150, a liquid crystal panel 160, a backlight unit 170, and a backlight driver 180.

The timing controller 130 receives a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, a clock signal, and a data signal from the outside. The timing controller 130 controls the operation timings of the data driver 150 and the gate driver 140 using timing signals such as a vertical synchronization signal, a horizontal synchronization signal, a data enable signal, and a clock signal.

The timing controller 130 can determine the frame period by counting the data enable signal of one horizontal period, so that the vertical synchronizing signal and the horizontal synchronizing signal supplied from the outside can be omitted. The control signals generated by the timing controller 130 include a gate timing control signal GDC for controlling the operation timing of the gate driver 140 and a data timing control signal DDC for controlling the operation timing of the data driver 150. [ ) May be included.

The gate driver 140 outputs a gate signal while shifting the level of the gate voltage in response to the gate timing control signal GDC supplied from the timing controller 130. The gate driver 140 supplies a gate signal to the liquid crystal panel 160 through the gate lines GL. The gate driver 140 may be formed in the form of an IC or a gate in panel in the liquid crystal panel 160.

The data driver 150 samples and latches the data signal DATA in response to the data timing control signal DDC supplied from the timing controller 130 and converts the sampled data signal into an analog form corresponding to the gamma reference voltage. The data driver 150 supplies the data signal DATA to the liquid crystal panel 160 through the data lines DL. The data driver 150 is formed in an IC form.

The liquid crystal panel 160 displays an image corresponding to the gate signal and the data signal DATA supplied from the driving unit including the gate driving unit 140 and the data driving unit 150. The liquid crystal panel 160 includes a plurality of sub-pixels SP for controlling light provided through the backlight unit 170. The plurality of sub-pixels SP has a pixel structure of RGB, RGBW or RGBG type.

One subpixel includes a switching thin film transistor SW, a storage capacitor Cst, and a liquid crystal layer Clc. The gate electrode of the switching thin film transistor SW is connected to the gate line GL1 and the source electrode thereof is connected to the data line DL1. One end of the storage capacitor Cst is connected to the drain electrode of the switching thin film transistor SW, and the other end of the storage capacitor Cst is connected to the common voltage line Vcom. The liquid crystal layer Clc is formed between the pixel electrode 1 connected to the drain electrode of the switching transistor SW and the common electrode 2 connected to the common voltage line Vcom.

The liquid crystal panel 160 includes a first substrate on which a thin film transistor or the like is formed, a second substrate on which a color filter or the like is formed, and a liquid crystal layer interposed between the first substrate and the second substrate. A lower polarizer is attached to the lower surface of the first substrate, and an upper polarizer is attached to the upper surface of the second substrate. The liquid crystal panel 160 is implemented in a TN (Twisted Nematic) mode, VA (Vertical Alignment) mode, IPS (In Plane Switching) mode, FFS (Fringe Field Switching) mode or ECB (Electrically Controlled Birefringence) mode.

The backlight unit 170 provides light to the liquid crystal panel 160. The backlight unit 170 includes light emitting diodes (hereinafter, LED) that emit light, a light guide plate that converts light emitted from the LED into a planar light source, and optical sheets that condense and diffuse the light emitted from the light guide plate.

The roughness sensing unit 120 generates an illumination signal (LIS) that senses (or accepts) ambient light and converts the sensed ambient light into an electrical signal to determine illumiance.

The roughness-sensing section 120 supplies the illumination signal LIS to the timing control section 130. The rough image sensing unit 120 may include a sensor unit such as an optical sensor, a camera, a light intensity sensor (Cds), etc. that can sense external light and convert it into an electric signal, and a sensor unit that can convert an analog electric signal into a digital electric signal A conversion unit, and the like.

The visual field detection unit 125 detects the position of the user's eyes based on the morphological analysis of the shape of the face of the user and the eyes of the user, (UES).

The visual field detection unit 125 supplies the visual field detection signal UES to the timing control unit 130. [ The visual field sensing unit 125 may include an image sensing unit for sensing the shape and eye of a user such as a camera in the form of a video signal, a morphological analysis unit for sensing the sensed image signal, (But the analysis unit may be included in another apparatus), and the like.

The backlight driver 180 generates a backlight control signal BLC that controls the brightness of the LEDs included in the backlight unit 170 in response to the signal supplied from the timing controller 130. [ The backlight driver 180 generates a backlight control signal BLC in a pulse width modulation (PWM) format and supplies the generated signals to the LEDs. The backlight driver 180 may include a power generator, an LED controller, and an output controller (output compensator).

The above-described liquid crystal display device is implemented in various products such as a television, a mobile device (e.g., a smart phone), a wearable display device (e.g., a smart watch), a vehicle display device (e.g. When the liquid crystal display device is implemented as a display device for user's convenience, it needs a function of improving day visibility in order to increase the discrimination power of the user.

However, in the liquid crystal display device proposed in the past, only simple functions such as improving daytime visibility by using only illumination information have been proposed.

Hereinafter, embodiments of the present invention will be described in order to solve the problems of the related art based on an example in which the liquid crystal display device is implemented as a navigation device, which is a vehicle display device. However, the invention to be described below should not be construed to be limited to a vehicle display device.

FIG. 3 is a view illustrating an example of a liquid crystal display according to a first embodiment of the present invention implemented as a display device for a vehicle, and FIG. 4 is a diagram for explaining a relationship between a temperature rise and a luminous efficiency.

1 and 3, the liquid crystal display according to the first embodiment of the present invention is implemented as a display device for a vehicle having a liquid crystal panel 160, a roughness-sensing section 120, and a vision-sensing section 125 do. The rough image sensing unit 120 and the visual field sensing unit 125 function as described with reference to FIG. The position where the roughness sensing unit 120 and the vision sensing unit 125 are installed may be the same as in FIG. 3, but is not limited thereto.

The liquid crystal display according to the first embodiment of the present invention recognizes the ambient illuminance using the rough illuminance sensing unit 120 and varies the brightness of the liquid crystal display according to the illuminance.

Because people have the characteristic (human visual system; HSV) that recognizes the brightness of the display device differently depending on the ambient illuminance, the ambient illuminance is used when the luminance is variable. As described above, the function of adjusting the brightness of the display device according to the illuminance has already been studied. However, the method of controlling only brightness is mostly illuminance as a variable.

For example, since the daytime illuminance of a liquid crystal display implemented by a vehicle display device in a car driving at almost 50000 to 100000 lux illumination such as a direct sunlight environment hardly fluctuates, a high current must be continuously used to realize a high luminance .

As shown in FIG. 4, when the brightness of the liquid crystal display device is adjusted according to the ambient illuminance, the brightness of the device is lowered due to a rise in the temperature of the device after a certain period of time.

The reason for this is that while recognizing the ambient illuminance and changing the luminance of the device according to the illuminance, maintaining the maximum luminance (driving the LEDs at the maximum current level continuously for maintaining the maximum luminance while the illuminance is recognized) And problems due to heat generation are caused. In addition, reliability and heat generation due to deterioration of the device and power consumption are increased.

Therefore, the liquid crystal display device according to the first embodiment of the present invention further comprises the visual field sensing unit 125 in addition to the roughness sensing unit 120. In addition to the surrounding illuminance, the user (driver) perceives the moment when the user gazes at the liquid crystal display implemented by the vehicle display device through the sensor, and adjusts the brightness corresponding to the ambient illuminance only for the time the user views the apparatus. Thus, the liquid crystal display device according to the first embodiment of the present invention can prevent deterioration of the device, thereby enhancing reliability, solving the problem of heat generation, and reducing power consumption.

FIG. 5 is a flowchart illustrating a method of adjusting brightness of an apparatus according to the first embodiment of the present invention. FIG. 6 is a view for helping understanding of the description of FIG. 5. FIG. And FIG. 8 is a diagram showing a configuration example of a backlight control signal according to a change in current of FIG.

1, 3, 5, and 6, the liquid crystal display 200 implemented as a vehicle display device senses illumination through the roughness sensing unit 120 (S110). In operation S120, the user USR senses whether the user USR is looking at the liquid crystal display device 200 implemented as a vehicle display device through the vision detection unit 125. [

At this time, if the user USR is not gazing at the liquid crystal display device 200 implemented by the vehicle display device, the device maintains the LED current of the backlight unit 170 at the same value as before (S140).

This will be described in detail with reference to the apparatus. The timing control unit 130 receives the illumination signal LIS and the visual field detection signal UES from the roughness sensing unit 120 and the visual field sensing unit 125, respectively.

The timing control unit 130 analyzes the roughness sensing unit 120 and the visual field detection signal UES. As a result of the analysis, it is detected that brightness is required because the ambient illuminance is high, but it is also detected that the user USR is not gazing at the liquid crystal display device 200 implemented by the vehicle display device.

Accordingly, the timing controller 130 supplies a signal to the backlight driver 180 to maintain the same brightness as before. As a result, the backlight driver 180 maintains the backlight control signal BLC controlling the brightness of the LEDs at the same value as before and supplies the backlight control signal BLC to the backlight unit 170.

In this way, when the user USR gazes at the front face or the like without looking at the liquid crystal display device 200 implemented by the vehicle display device (1 in Fig. 6), the brightness of the device remains the same (Maintains low brightness) and lowers power consumption.

At this time, the low brightness level may be 0 to the white brightness range within the specification of the apparatus, but is not limited thereto. According to such a driving method, daytime visibility of the apparatus is lowered, but power consumption is drastically reduced.

On the other hand, when the user USR looks at the liquid crystal display 200 implemented by the on-vehicle display device during operation (Y), the device increases the LED current of the backlight unit 170 to a value different from the previous one (S130 ).

This will be described in detail with reference to the apparatus. The timing control unit 130 receives the illumination signal LIS and the visual field detection signal UES from the roughness sensing unit 120 and the visual field sensing unit 125, respectively.

The timing control unit 130 analyzes the roughness sensing unit 120 and the visual field detection signal UES. As a result of the analysis, it is detected that the brightness of the surroundings is high due to the high ambient illumination, and the user USR senses that the user is gazing at the liquid crystal display device 200 implemented by the vehicle display device.

Accordingly, the timing controller 130 supplies a signal to the backlight driver 180 to increase the brightness differently than before. As a result, the backlight driving unit 180 varies the backlight control signal BLC, which controls the brightness of the LEDs, to an increased value, and supplies the backlight control signal BLC to the backlight unit 170. [

In this way, when the user USR looks at the liquid crystal display device 200 implemented by the in-vehicle display device (2 in Fig. 6), the brightness of the device is increased corresponding to the illuminance. At this time, the user (USR) strikes the device at about 1 to 10 seconds during operation.

Therefore, in consideration of the safety of the user (USR), brightness can be increased to approximately N (N is an integer equal to or greater than 1) seconds using the maximum current that the LEDs can provide to provide high discrimination power. According to such a driving method, the daytime visibility of the apparatus is automatically improved temporally and instantaneously.

6), the current supplied to the LEDs of the backlight unit 180 is also lower than the current supplied to the backlight unit 180. In this case, As shown in (1) of (7), it can be kept constant.

6), the current supplied to the LEDs of the backlight unit 180 is the same as the currents supplied to the LEDs of the backlight unit 180, It can be changed as well.

The current supplied to the LEDs of the backlight unit 180 becomes temporarily and instantaneously high in the situation (b) when the user USR strikes the liquid crystal display device 200 implemented with the on-vehicle display device during operation. However, the current supplied to the LEDs of the backlight unit 180 is lowered as in the cases (a) and (c) when the user USR does not gaze at the liquid crystal display device 200 implemented by the on-vehicle display device during operation .

8, when the user USR observes the liquid crystal display device 200 implemented by the on-vehicle display device during operation (b), the backlight control signal BLC is displayed in a state (a) (Duty ratio variable) can be generated. For example, in case (b), the duty ratio of the pulse width signal is higher than that of (a) and (c), whereas in cases (a) and (c), the duty ratio of the pulse width signal is lower than (b).

≪ Embodiment 2 >

FIG. 9 is a flowchart illustrating a method of adjusting brightness of an apparatus according to a second exemplary embodiment of the present invention, and FIG. 10 is a diagram illustrating results of brightness versus outdoor environment contrast ratio.

1, 3, 6, and 9, the liquid crystal display device 200 implemented as a vehicle display device senses illumination through the roughness sensing unit 120 (S210). Then, the optimum brightness is calculated based on the sensed information through the roughness sensing unit 120 (S220). In operation S230, the USR senses whether or not the user USR is looking at the liquid crystal display 200 implemented by the vehicle display device through the visual field sensing unit 125.

At this time, if the user USR is not gazing at the liquid crystal display device 200 implemented by the vehicle display device (N), the device maintains or reduces the LED current of the backlight unit 170 as before (S260) . Then, the brightness of the liquid crystal panel 160 is maintained or decreased as before (S270).

This will be described in detail with reference to the apparatus. The timing control unit 130 receives the illumination signal LIS and the visual field detection signal UES from the roughness sensing unit 120 and the visual field sensing unit 125, respectively.

The timing controller 130 calculates an appropriate brightness based on the signal provided from the roughness sensing unit 120 and analyzes the visual sense signal UES. As a result of the analysis, it is detected that brightness is required because the ambient illuminance is high, but it is also detected that the user USR is not gazing at the liquid crystal display device 200 implemented by the vehicle display device.

Accordingly, the timing controller 130 controls the backlight driver 180 to maintain or decrease the brightness (as in the previous case where the user gazed at the device but was not currently in the current state, Signal. As a result, the backlight driver 180 generates the backlight control signal BLC at a value that maintains or reduces the current of the LEDs to the same value as before, and supplies the backlight control signal BLC to the backlight unit 170. [

The luminance of the liquid crystal panel 160 can be automatically maintained or decreased as before due to a change in current supplied to the LEDs. At this time, the brightness of the data signal (or the gamma voltage) supplied to the liquid crystal panel 160 may be adjusted together with the current of the LEDs.

In this way, when the user USR gazes at the front face or the like without looking at the liquid crystal display device 200 implemented by the vehicle display device (1 in Fig. 6), the brightness of the device remains the same (Maintains low brightness) and lowers power consumption. At this time, the low brightness level may be 0 to the white brightness range within the specification of the apparatus, but is not limited thereto. According to such a driving method, daytime visibility of the apparatus is lowered, but power consumption is drastically reduced.

Alternatively, when the user USR gazes at the liquid crystal display 200 implemented with the on-vehicle display device during operation (Y), the device increases or maintains the LED current of the backlight unit 170 with a different value than before (S240). The brightness of the liquid crystal panel 160 is increased or maintained unlike the previous case (S250).

This will be described in detail with reference to the apparatus. The timing control unit 130 receives the illumination signal LIS and the visual field detection signal UES from the roughness sensing unit 120 and the visual field sensing unit 125, respectively.

The timing controller 130 calculates an appropriate brightness based on the signal provided from the roughness sensing unit 120 and analyzes the visual sense signal UES. As a result of the analysis, it is detected that the brightness of the surroundings is high due to the high ambient illumination, and the user USR senses that the user is gazing at the liquid crystal display device 200 implemented by the vehicle display device.

Accordingly, the timing controller 130 supplies a signal to the backlight driver 180 to increase or maintain the brightness (to be changed to the maintenance command instead of increase, in the case where the user has gazed at the device both before and at present) do. As a result, the backlight driver 180 generates the backlight control signal BLC at a value that increases or maintains the brightness of the LEDs, and supplies the generated backlight control signal BLC to the backlight unit 170.

The luminance of the liquid crystal panel 160 can be automatically increased or maintained by the current change supplied to the LEDs. At this time, the luminance of the data signal (or the gamma voltage) supplied to the liquid crystal panel 160 may be adjusted together with the current of the LEDs.

In this way, when the user USR looks at the liquid crystal display device 200 implemented by the in-vehicle display device (2 in Fig. 6), the brightness of the device is increased corresponding to the illuminance. At this time, the user (USR) strikes the device at about 1 to 10 seconds during operation.

Therefore, in consideration of the safety of the user (USR), brightness can be increased to approximately N (N is an integer equal to or greater than 1) seconds using the maximum current that the LEDs can provide to provide high discrimination power. According to such a driving method, the daytime visibility of the apparatus is automatically improved temporally and instantaneously.

Meanwhile, in the above description, it is exemplified that the step of calculating the appropriate brightness (S220) is performed after the step 210 of sensing the illumination. However, this may be performed in step S230 of sensing the field of view of the user USR, or after increasing or maintaining the LED current in step S240. The reason for this is that proper brightness is calculated when not observing the device of the user (USR), but if not used, time or electric loss due to response time or memory usage may occur.

Meanwhile, the timing controller 130 and the like may gradually change the increase and decrease of the brightness to lower the discomfort due to the brightness change of the USR field of view. In the above example, an appropriate brightness calculation is performed as a method for maintaining an appropriate luminance. At this time, appropriate brightness calculation may be performed linearly or hierarchically according to the surrounding illuminance, or a value stored in the form of a lookup table may be referred to.

As a result of experimenting with the device of the first and second embodiments of the present invention and experimenting with the illuminance of 50000 ~ 100000 lux such as the direct sunlight environment, the brightness is increased without degrading the device to improve visibility and power consumption I could.

As shown in FIG. 10, when the brightness is doubled, the ambient contrast ratio (ACR) of the liquid crystal display P2 implemented by the vehicle display device is about three times higher than that of the conventional structure P1 Respectively.

In addition, when the user's view is directed to the front regardless of the illuminance, the power consumption mode is switched to the low power consumption mode, so that the effect of reducing the power consumption compared to the conventional structure is increased (about 37.5% The brightness is increased corresponding to the illuminance and is not maintained for a long time but is temporarily increased only when the user stare, and then decreased.

In the first and second embodiments of the present invention, the brightness is increased when the ambient illuminance is high. However, in a situation where the illuminance is low and the user does not gaze, the brightness may be lower than before to further reduce power consumption. That is, the present invention can increase, decrease, or maintain the brightness according to the ambient illuminance, and can operate the apparatus while considering outdoor visibility and power consumption.

In the first and second embodiments of the present invention, the coarse detection unit and the visual field detection unit are separated from each other. However, the rough image sensing unit and the vision sensing unit may be integrated into one device such as a camera.

In the first and second embodiments of the present invention, the coarse detection unit and the visual field detection unit are linked (connected) to the timing control unit. However, the rough image sensing unit and the visual field sensing unit may be interlocked with a control unit capable of controlling the brightness.

In the first and second embodiments of the present invention, a liquid crystal display device has been described as an example of an embodiment. Accordingly, in the above description, the backlight driver and the backlight unit are controlled to control brightness (or luminance).

However, when the display device is configured as an organic light emitting display device, the brightness of the organic light emitting diode may be adjusted according to the user's gaze. In this case, the method of controlling the brightness of the organic light emitting diode may vary depending on the driving method of the organic light emitting display device, but the data signal, the gamma voltage, and the high potential voltage are usually controlled.

As described above, according to the present invention, brightness (or brightness) is increased, maintained or reduced in correspondence with illuminance and user's gaze, thereby increasing the outdoor environment contrast ratio and reducing power consumption. In addition, since the brightness (or brightness) is controlled in accordance with the illuminance and the user's gaze, the present invention can improve the reliability by preventing deterioration of the device and solve the problem of heat generation.

While the present invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, It will be understood that the invention may be practiced. It is therefore to be understood that the embodiments described above are to be considered in all respects only as illustrative and not restrictive. In addition, the scope of the present invention is indicated by the following claims rather than the detailed description. Also, all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

120: coarse guide detection unit 125: visual field detection unit
130: timing controller 140: gate driver
150: data driver 160: liquid crystal panel
170: Backlight unit 180: Backlight driver
LIS: Illumination signal UES: Field of view detection signal
BLC: Backlight control signal

Claims (7)

A panel for displaying an image;
A visual field sensing unit for sensing a position where a user's eyes stay; And
And a control unit interlocked with the visual field sensing unit and varying brightness of the panel according to whether the user gazes at the panel. The method according to claim 1,
The control unit
Wherein the brightness of the panel is increased when the user gazes at the panel and the brightness of the panel is lowered when the user does not gaze at the panel. The method according to claim 1,
Further comprising a roughness detecting section for detecting roughness,
The control unit
Wherein the brightness of the light emitting diodes is increased when the user gazes at the panel while the illuminance is high. The method according to claim 1,
Further comprising a roughness detecting section for detecting roughness,
The control unit
Wherein the duty ratio of a current or a pulse width signal supplied to the light emitting diodes is varied when the user gazes at the panel in a state where the illuminance is high. The method according to claim 1,
Further comprising a roughness detecting section for detecting roughness,
The control unit
Wherein the brightness of the panel is changed after deriving an appropriate brightness according to the illuminance. Detecting whether the user is staring the panel; And
And varying the brightness of the panel in response to whether or not the user is gazing at the panel. The method according to claim 6,
The step of varying the brightness comprises:
Wherein the duty ratio of a current or a pulse width signal supplied to the light emitting diodes is varied in order to vary the brightness of the panel when the user gazes at the panel.

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