KR20070064150A - Display apparatus - Google Patents

Abstract

A display device is provided to reduce the power consumption by controlling the brightness of a light source according to brightness of an external light, and reduce the number of component parts by mounting a light source driver within a driving chip. A display panel includes a light sensor for outputting a sensing signal in response to an external light. A driving chip(300) is mounted on the display panel. The driving chip includes a dimming controller(310) for comparing the sensing signal with a predetermined reference signal to output a dimming control signal, a mode selector(320) for selecting a control mode according to the dimming control signal, and a first light source driver(330) for outputting a first light source driving signal in response to a first control signal of the mode selector. A driving circuit board includes a second light source driver(410) for outputting a second light source driving signal in response to a second control signal of the mode selector. A light source(500) generates light in response to the first light source driving signal and the second light source driving signal.

Description

Display device {DISPLAY APPARATUS}

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention.

FIG. 2 is a diagram schematically illustrating a display panel, a driving circuit board, and a light source illustrated in FIG. 1.

3 is a block diagram illustrating in detail the driving chip, the second light source driver, and the light source illustrated in FIG. 2.

4 is a flowchart illustrating a light source driving method of a display device according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: display device 200: display panel

210: optical sensor unit SS: sensing signal

300: driving chip 310: dimming control unit

DCS: dimming control signal 312: signal amplifier

314: signal comparator 320: mode selector

CNT1: first control signal CNT2: second control signal

330: first light source driving unit DS1: first light source driving signal

DS2: second light source drive signal 340: input pin

350: output pin 400: drive circuit board

410: second light source driver 500: light source

The present invention relates to a display device, and more particularly, to a display device having a brightness control function of a light source according to the brightness of external light.

In general, various electronic devices such as a mobile communication terminal, a digital camera, a notebook computer, a monitor, and a TV are provided with an image display device for displaying an image. Various kinds of image display apparatuses may be used, but a flat panel display apparatus having a flat plate shape is mainly used due to the characteristics of an electronic device, and a liquid crystal display (LCD) is particularly widely used among flat panel display apparatuses.

Such a liquid crystal display device is one of flat panel display devices that display an image using liquid crystal, and is thinner and lighter than other flat panel display devices, and has an advantage of low driving voltage and low power consumption. Widely used throughout.

The display device includes a display panel that displays an image using light, a light source that supplies light to the display panel, and a light source driver that drives the light source.

As a light source, a cold cathode fluorescent lamp (CCFL) or a light emitting diode is mainly used.

The display device using the light emitting diodes as a light source includes a light source driver for controlling and driving the luminance of light emitted from the light emitting diodes.

The light source driver is driven in a dimming mode for driving in a normal driving mode or a low luminance driving mode according to the brightness of external light, thereby reducing power consumption. This can increase the use time for mobile products that use power supplies such as batteries with constant capacitance.

Conventionally, a separate signal line is used to connect an external light source driver including a dimming function, which is a brightness control function, and an external device for controlling the same. This causes a problem to be connected through a separate signal line from the external device.

Accordingly, the present invention takes into account such a conventional problem, and the present invention reduces the power consumed when driving the light source in the low brightness driving mode, and reduces the number of separate parts by mounting the light source driving unit inside the driving chip. It provides a display device that can be.

The display device according to an aspect of the present invention described above includes a display panel, a driving chip, a driving circuit board, and a light source. The display panel includes an optical sensor unit that outputs a sensing signal in response to luminance of external light.

The driving chip is mounted on the display panel, and includes a dimming controller, a mode selector, and a first light source driver. The dimming controller compares the sensing signal with a preset reference signal and outputs a dimming control signal. The mode selector selects a control mode according to the dimming control signal. The first light source driver outputs a first light source driving signal in response to a first control signal of the mode selector.

The driving circuit board may include a second light source driving unit configured to output a second light source driving signal in response to a second control signal of the mode selection unit. The light source generates light in response to the first light source driving signal and the second light source driving signal.

The dimming control unit includes a signal amplifier for amplifying the sensing signal and a signal comparison unit for outputting the dimming control signal by comparing the sensing signal amplified by the signal amplifying unit with the reference signal.

The mode selector outputs the first control signal to the first light source driver when the sensing signal is less than or equal to the reference signal, and when the sensing signal is greater than or equal to the reference signal, the second light source driver to output the second control signal. Output a control signal.

The second light source driver outputs the level of the second light source driving signal in steps according to the second control signal.

  The driving chip includes an input pin for receiving an external input signal for individually driving the first light source driver, and an output pin for outputting the second control signal to the second light source driver. It is provided.

According to the display device, inefficient power consumption is reduced by adjusting the brightness of the light source according to the brightness of external light, and the number of separate parts can be reduced by mounting the light source driver inside the driving chip.

Hereinafter, with reference to the accompanying drawings, it will be described in detail a preferred embodiment of the present invention.

1 is an exploded perspective view illustrating a display device according to an exemplary embodiment of the present invention, and FIG. 2 is a view schematically illustrating a display panel, a driving circuit board, and a light source illustrated in FIG. 1.

1 and 2, a display device 100 according to an exemplary embodiment of the present invention includes a display panel 200, a driving chip 300, a driving circuit board 400, and a light source 500.

The display panel 200 displays an image using light supplied from the light source 500. The display panel 200 includes a lower substrate 220, an upper substrate 230 facing the lower substrate 220, and a liquid crystal layer (not shown) disposed between the lower substrate 220 and the upper substrate 230. .

The lower substrate 220 is a transparent glass substrate in which a thin film transistor (hereinafter, referred to as TFT) as a switching element is formed in a matrix form. Data and gate lines are respectively connected to the source and gate terminals of the TFTs, and a pixel electrode made of a transparent conductive material is connected to the drain terminal.

The upper substrate 230 includes a color filter (not shown) for realizing color and a common electrode (not shown) facing the pixel electrode of the lower substrate 220. The color filter may be formed on the lower substrate 220.

The liquid crystal layer disposed between the lower substrate 220 and the upper substrate 230 is composed of liquid crystal molecules having electrical and optical properties such as anisotropic dielectric constant and anisotropic refractive index.

When power is applied to the gate terminal of the TFT and the TFT is turned on, an electric field is formed between the pixel electrode and the common electrode. By the electric field, the arrangement of liquid crystal molecules of the liquid crystal layer disposed between the lower substrate 220 and the upper substrate 230 is changed, and the transmittance of light is changed according to the arrangement of the liquid crystal molecules to display an image of a desired gray scale. .

The display panel 200 displays an image by using light generated at different luminance according to the luminance of the external light. That is, the display panel 200 displays an image in a low luminance mode, that is, a dimming mode when the external light is high, and displays the image in a normal luminance mode when the external light is low.

The display panel 200 includes an optical sensor unit 210 that outputs a sensing signal SEN_S in response to luminance of external light. The optical sensor unit 210 is formed on the lower substrate 220 of the display panel 200.

The optical sensor unit 210 is designed to locally open the upper metal layer (not shown) of the channel of the thin film transistor so that external light may flow into the thin film transistor channel. Therefore, when the luminance of the external light is high, the optical sensor unit 210 outputs the sensing signal SEN_S corresponding to the low luminance mode. In addition, when the luminance of the upper light is low, the optical sensor unit 210 outputs the sensing signal SEN_S corresponding to the normal luminance mode.

The optical sensor 210 may be formed in plurality in the display panel 200. For example, the plurality of optical sensor units 210 output a separate sensing signal SEN_S by dividing a predetermined range. As another example, the first optical sensor unit 210 outputs the sensing signal SEN_S in response to the luminance of the external light with respect to the entire display panel 200. Only when the first optical sensor unit 210 cannot output the sensing signal SEN_S, one of the remaining optical sensor units 210 outputs the sensing signal SEN_S. .

The driving chip 300 includes a light source driving unit which drives the light source 500 to generate light by varying the luminance of light according to the sensing signal SEN_S output by the optical sensor unit 210.

The driving chip 300 is mounted on the lower substrate 220 of the display panel 200 and generates a driving signal for driving the display panel 200 in response to various control signals applied from the outside. The driving chip 300 is mounted on one side of the lower substrate 220 by, for example, a chip on glass (COG) process.

In the present invention, the driving chip 300 is represented as a single chip outputting the data signal and the gate signal from one chip, but the driving chip 300 outputs the data line chip and the gate signal for outputting the data signal. It may be composed of a gate line chip.

The driving chip 300 will be described in more detail with reference to FIG. 3.

The driving circuit board 400 includes a second light source driver 410. The second light source driver outputs a second light source driving signal LED_DS2 for driving the light source 500 in the normal luminance mode.

The driving circuit board 400 is connected to one side of the lower substrate 220 on which the driving chip 300 is mounted. The driving circuit board 400 is electrically connected to the lower substrate 220 through, for example, an anisotropic conductive film (ACF).

Although not shown, the driving circuit board 400 includes elements such as a capacitor or a resistor for generating the control signal and stabilizing the control signal.

Since the driving circuit board 400 is flexible, the driving circuit board 400 is bent from the display panel 200 to the rear surface of the bottom chassis 550 to be described later. The driving circuit board 400 is fixed through, for example, double-sided tape.

The light source 500 generates light having a predetermined brightness. The light source 500 may be, for example, a plurality of light emitting diodes.

The light source 500 generates light by varying the luminance according to the luminance of the external light. That is, when the brightness of the external light is high, light corresponding to the low brightness is generated, and when the brightness of the external light is low, light corresponding to the normal brightness is generated.

The driving circuit board 400 and the light source 500 will be described in more detail with reference to FIG. 3.

The display device 100 further includes a light guide plate 510, a reflective sheet 520, and optical sheets 530 to improve light efficiency, a mold frame 540, and a bottom chassis 550 to accommodate them.

The light guide plate 510 guides the light incident from the light sources 500 toward the display panel 200. The light guide plate 510 is made of a transparent material to minimize the loss of light. For example, the light guide plate 510 is made of polymethyl methacrylate (PMMA) having excellent strength.

The reflective sheet 520 is disposed under the light guide plate 510. The reflective sheet 520 reflects light leaking to the outside through the lower surface of the light guide plate 510 into the light guide plate 510 to improve light utilization efficiency. The reflective sheet 520 is made of a material having high light reflectance.

The optical sheets 530 are disposed on the light guide plate 510. The optical sheets 530 may include a diffusion sheet for diffusing the light emitted from the light guide plate 200 to improve luminance uniformity and a prism sheet for condensing the light in the front direction to improve the front luminance of the light.

The mold frame 540 has a rectangular frame shape with an opening therein. The mold frame 540 is made of a plastic material. The optical sheets 530 may be accommodated in the mold frame 540 so that the optical sheets 530 may be supported in a predetermined region on the light guide plate 510.

The bottom chassis 550 is coupled to the mold frame 540 to cover the lower portion of the light guide plate 510. For example, the bottom chassis 550 is made of a metal having excellent strength compared to the mold frame 540, and is hooked with the mold frame 540.

3 is a block diagram specifically illustrating a driving chip and a second light source driving unit illustrated in FIG. 2.

2 and 3, the driving chip 300 includes a dimming controller 310, a mode selector 320, and a first light source driver 330.

The dimming control unit 310 outputs a dimming control signal DIM_CS by comparing the sensing signal SEN_S with a preset reference signal CS. The dimming control unit 310 compares the sensing signal SEN_S amplified by the signal amplifying unit 312 and the signal amplifying unit 312 and the reference signal DS to amplify the sensing signal SEN_S and dimming control signal DIM_CS. And a signal comparison unit 314 for outputting the signal.

The mode selector 320 selects a control mode according to the dimming control signal DIM_CS. When the sensing signal SEN_S is less than or equal to the reference signal CS, the mode selector 320 outputs the first control signal CNT1 to the first light source driver 330, and the sensing signal SEN_S corresponds to the reference signal (SEN_S). In the case of abnormality of CS, the second control signal CNT2 is output to the second light source driver 410.

The first light source driver 330 outputs the first light source driving signal LED_DS1 in response to the first control signal CNT1 of the mode selector 320. The first light source driver 330 outputs the first light source driving signal CNT1 to the light source when the brightness of the external light is low, that is, when the brightness of the external light is low. That is, the first light source driver 330 outputs a light source driving signal corresponding to normal luminance.

The first light source driver 330 may be mounted in the driving chip 300 to solve a problem caused by connection with an external device for controlling the light source driver. In addition, by mounting the light source driver for driving the light source 500 in the driving chip 300, it may be freely changed according to the characteristics of the display panel 200.

In addition, the driving chip 300 may further include a panel driver (not shown) that provides an image control signal for driving the display panel 200. The panel driver applies a data signal and a gate signal to data lines and gate lines of the display panel 200.

Meanwhile, the driving chip 300 includes an input pin 340 that receives an external input signal for individually driving the first light source driver 330. For example, to apply the external input signal EX_IN when the first light source driver 330 is to be driven separately by an external device, apart from the sensing signal SEN_S output by the optical sensor unit 210. to be. As another example, when the optical sensor unit 210 is not operated, an external input signal corresponding to the sensing signal SEN_S is individually input to the first light source driver 330 through an input pin 340.

In addition, the driving chip 300 includes an output pin 350 for outputting the second control signal CNT2 to the second light source driver 410. The second control signal CNT2 is output to the second light source driver 410 mounted on the driving circuit board 400 through an output pin 350. In addition, the sensing signal SEN_S may be output to the outside through the output pin 350 and may be fed back to the external device to adjust the second light source driver 410.

The driving circuit board 400 includes a second light source driving unit 410 that outputs a second light source driving signal LED_DS2 in response to the second control signal CNT2 of the mode selection unit 320.

The second light source driver 410 outputs the second light source driving signal LED_DS2 in response to the second control signal CNT2 of the mode selector 320. The second control signal CNT2 of the mode selector 320 is a signal output to the second light source driver 410 when the sensing signal SEN_S is equal to or greater than the reference signal CS. That is, the second light source driving signal LED_DS2 is a light source driving signal when the luminance of the external light is high, that is, the low luminance mode.

In addition, the second light source driver 410 may change the level of the second light source driving signal LED_DS2 in steps according to the second control signal CNT2 and output the resultant. That is, the second light source driver 410 sequentially outputs the second light source driving signal LED_DS2 corresponding to a specific value according to the brightness of the external light. Therefore, inefficient power consumption can be reduced by adjusting the brightness of the light source according to the brightness of the external light.

The light source 500 generates light in response to the first light source driving signal LED_DS1 and the second light source driving signal LED_DS2. Since the first light source driving signal LED_DS1 is a signal corresponding to the normal luminance mode, the light source 500 generates light corresponding to the normal luminance. In addition, since the second light source driving signal LED_DS2 is a signal corresponding to the dimming mode, the light source 500 generates light of low luminance, that is, low luminance.

In addition, when the second light source driver 410 gradually changes the level of the second light source driving signal LED_DS2 according to the second control signal CNT1 and outputs the light source 500, the light source 500 uses the second light source driving signal ( In response to LED_DS2), brightness is changed in steps to generate light. For example, when the luminance of the external light is very high, the light source 500 does not generate light, and when the luminance is high, light corresponding to the low luminance is generated. In addition, when the brightness is low, light corresponding to a high brightness is generated, and when the brightness is very low, light corresponding to a very high brightness is generated.

In the present invention, the light source 500 does not set a specific value that is generated by changing the brightness of the light in steps, but specifies the second light source driving signal LED_DS2 output by the second light source driver 410 according to the brightness of the external light. In the case of outputting step by step according to the value of the light source 500 will also change step by step to generate light.

4 is a flowchart illustrating a light source driving method of a display device according to an exemplary embodiment of the present invention.

3 and 4, in the light source driving method according to an embodiment of the present disclosure, sensing the brightness of external light (S100), amplifying the sensing signal SEN_S (S110), and sensing signal SEN_S And comparing and determining the reference signal CS (S120).

In addition, when the sensing signal SEN_S is less than or equal to the reference signal CS, the driving of the first light source driver 330 (S130) and the light source 500 emit light at normal luminance (S140). do.

In addition, when the sensing signal SEN_S is equal to or greater than the reference signal CS, the driving of the second light source driver 410 (S150) and the light source 500 emits light at low luminance (S160). do.

In operation S100, the optical sensor unit 210 formed on the display panel 200 senses the luminance of the external light. Accordingly, the optical sensor unit 210 outputs the sensing signal SEN_S in response to the luminance of the external light.

In operation S110, after the signal amplifier 312 disposed in the driving chip 300 receives the sensing signal SEN_S, the signal amplifier 312 amplifies the sensing signal SEN_S. The signal amplifier 312 may be, for example, an OP-AMP. The amplification signal SEN_S is amplified and transmitted to the signal comparator 314, so that the signal comparator 314 accurately compares the sensing signal SEN_S and the reference signal CS.

In operation S120, the signal comparator 314 compares the sensing signal SEN_S with the reference signal CS. In detail, the signal comparator 314 compares the magnitude of the sensing signal SEN_S amplified by the signal amplifier 312 and the reference signal CS to output the first control signal CNT1, or the second control. It is determined whether to output the signal CNT2.

In operation S130, when the sensing signal SEN_S is less than or equal to the reference signal CS, the first light source driver 330 drives in operation S130. Specifically, when the sensing signal SEN_S is less than or equal to the reference signal CS, the mode selector 320 outputs the first control signal CNT1 corresponding to the normal luminance mode, and outputs the first control signal CNT1. In response, the first light source driver 330 outputs the first light source driving signal LED_DS1.

In operation S140, the light sources 500 emit light at normal luminance according to the first light source driving signal LED_DS1. That is, the light emitting diodes generate light corresponding to the normal luminance in response to the first light source driving signal LED_DS1.

In operation S150, when it is determined in operation S120 that the sensing signal SEN_S is equal to or greater than the reference signal CS, the second light source driver 410 is driven. In detail, when the sensing signal SEN_S is greater than or equal to the reference signal CS, the mode selector 320 outputs the second control signal CNT2 corresponding to the low luminance mode and outputs the second control signal CNT2. In response, the second light source driver 410 outputs the second light source driving signal LED_DS1.

In operation S160, the light sources 500 emit light at low luminance according to the second light source driving signal LED_DS2. That is, the light emitting diodes generate light corresponding to the low luminance in response to the second light source driving signal LED_DS2.

As such, inefficient power consumption may be reduced by adjusting the brightness of the light source 500 according to the brightness of the external light. In addition, by mounting the light source driver inside the driving chip 300, the burden of connecting through a separate external device can be reduced.

According to such a display device, an inefficient power consumption can be reduced by adjusting the brightness of the light source according to the brightness of the external light. In addition, by mounting the light source driver inside the driving chip, it is possible to reduce the number of separate components required for connection with an external device for controlling the light source driver.

In the detailed description of the present invention described above with reference to a preferred embodiment of the present invention, those skilled in the art or those skilled in the art having ordinary knowledge in the scope of the invention described in the claims to be described later It will be understood that various modifications and variations can be made in the present invention without departing from the scope of the present invention.

Claims (9)

A display panel including an optical sensor unit configured to output a sensing signal in response to luminance of external light; A dimming controller mounted on the display panel and configured to compare the sensing signal with a preset reference signal and output a dimming control signal, a mode selector for selecting a control mode according to the dimming control signal, and a first control signal of the mode selector A driving chip including a first light source driver configured to output a first light source driving signal in response to the first light source driving signal; A driving circuit board including a second light source driving unit configured to output a second light source driving signal in response to a second control signal of the mode selection unit; And And a light source generating light in response to the first light source driving signal and the second light source driving signal. The method of claim 1, wherein the dimming control unit A signal amplifier for amplifying the sensing signal; And And a signal comparator configured to compare the sensing signal amplified by the signal amplifier and the reference signal to output the dimming control signal. The method of claim 1, wherein the mode selector Outputting the first control signal to the first light source driver when the sensing signal is less than or equal to the reference signal, And when the sensing signal is greater than or equal to the reference signal, outputting the second control signal to the second light source driver. The display device of claim 1, wherein the second light source driver outputs the second light source driving signal by changing a level of the second light source driving signal in steps according to the second control signal. The display device of claim 1, wherein the driving chip comprises an input pin configured to receive an external input signal for individually driving the first light source driver. The display device of claim 1, wherein the driving chip comprises an output pin for outputting the second control signal to the second light source driver. The display panel of claim 1, wherein the display panel comprises: A lower substrate on which the optical sensor unit is formed; An upper substrate facing the lower substrate; And And a liquid crystal layer disposed between the lower substrate and the upper substrate. The display device of claim 1, wherein the driving chip further comprises a panel driver configured to provide an image control signal for driving the display panel. The display device of claim 1, wherein the light source comprises one or more light emitting diodes.

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