KR100767374B1 - Liquid crystal display adaptive brightness - Google Patents

Abstract

The present invention discloses a liquid crystal display device adapted to the illuminance of the surrounding environment.

According to the present invention, the illuminance sensing unit senses the brightness level of the surroundings and outputs a dimming control signal, and the luminance generating unit includes an inverter and a lamp to provide light having a predetermined brightness to the liquid crystal panel in response to the dimming control signal. . Here, it is preferable that the illuminance detector includes a photo transistor whose current amount changes in accordance with the ambient illumination level, and outputs a voltage drop amount of a predetermined resistance through which the amplification current of the photo transistor flows as a dimming control signal.

In operation, the luminance level is increased when the ambient light level is bright, and the luminance level is lowered when the ambient light level is low, thereby minimizing the difference between the ambient light level and the luminance level of the liquid crystal display. In addition, the user may experience visual fatigue.

Luminance, Adaptive, Illuminance, Brightness, Liquid Crystal, LCD, Monitor

Description

Liquid crystal display adapted to illuminance {LIQUID CRYSTAL DISPLAY ADAPTIVE BRIGHTNESS}

1 is a view for explaining a liquid crystal display device adapted to illuminance according to an embodiment of the present invention.

2A is a circuit diagram illustrating an example of an illumination intensity sensing unit according to the present invention.

FIG. 2B is a diagram for explaining a simulation result according to FIG. 2A.

3A is a circuit diagram illustrating another example of an illuminance sensor according to the present invention.

FIG. 3B is a diagram for explaining a simulation result according to FIG. 3A.

<Description of the symbols for the main parts of the drawings>

100: illuminance detecting unit 200: luminance generating unit

210: inverter 220: lamp

Q1, Q2: phototransistor

The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device adapted to the illumination of the surrounding environment.

Recently, the popularity of monitor products is accelerating due to the falling prices of liquid crystal display devices, especially TFT-LCDs using thin film transistors (TFTs) as switching elements. In other words, there are many products that improve the visibility by raising the brightness of LCD monitors to the level of CRT monitors, and even 400 까지 / ㎡ LCD monitor products.

However, since such monitor products raise the luminance level unilaterally in order to improve visibility, there is a problem in that the brightness level of the monitor is too bright for an actual user, and eyes are tired.

In order to reduce such eyestrain, the brightness of the backlight may be adjusted through a device such as an on screen display (OSD), but there is a problem in that it is inconvenient for the user to manually adjust the brightness of the backlight.

In addition, since eye fatigue varies depending on the surrounding situation, that is, the brightness level of the surrounding, the inconvenience of having to adjust the brightness individually in conjunction with the surrounding situation is accompanied.

That is, the brightness of the LCD monitor causes eye fatigue due to the difference between the ambient illuminance level and the brightness level of the monitor. Therefore, when the brightness of the LCD monitor is too bright or dark than the ambient illuminance level, the visual fatigue is quickly felt.

Therefore, when working in a bright office environment and working with the lights off, the monitor becomes brighter than the illuminance level, resulting in visual fatigue, and conversely, when working in a dark environment and turning on the light, the monitor becomes darker than the illuminance level. There is a problem of fatigue.

Accordingly, the present invention has been made in an effort to solve such a conventional problem, and an object of the present invention is to adjust a luminance level in conjunction with an ambient illuminance level so as to reduce illuminance of a user's eyes and to adjust the illumination level. To provide a device.

A liquid crystal display device adapted to illuminance according to one feature for realizing the above object of the present invention includes a data driver, a gate driver, and a liquid crystal panel,

An illuminance sensor configured to detect a brightness level of the surroundings and output a dimming control signal; And

And a brightness generating unit including an inverter and a lamp to provide light having a predetermined brightness to the liquid crystal panel in response to the dimming control signal. Here, the illuminance detecting unit may include a photo transistor whose current amount changes according to an ambient illuminance level, and outputs, as the dimming control signal, a voltage drop amount of a predetermined resistor through which an amplification current of the photo transistor flows. .

According to the liquid crystal display device adapted to such an illuminance, when the illuminance level of the surrounding environment is bright, the luminance level is increased, and when the illuminance level of the surrounding environment is dark, the luminance level is lowered to reduce the illuminance level of the surrounding environment and the liquid crystal display device. By minimizing the difference with the luminance level, the visual fatigue felt by the user can be reduced.                     

Then, embodiments will be described so that those skilled in the art can easily implement the present invention.

1 is a view for explaining a liquid crystal display device adapted to illuminance according to an embodiment of the present invention.

Referring to FIG. 1, a liquid crystal display device adapted to illuminance according to an exemplary embodiment of the present invention includes an LCD module including an illuminance sensor 100, a luminance generator 200, a data driver, a gate driver, and a liquid crystal panel. Since the LCD module is well known, detailed operation thereof is omitted.

The illuminance detector 100 detects an ambient luminance level of the liquid crystal display and provides a dimming control signal DIMCON to the luminance generator 200 that is linked to the detected luminance level.

The luminance generating unit 200 includes an inverter 210 and a lamp 220. By limiting the tube current of the lamp 220 based on the dimming control signal DIMCON, the luminance level is adjusted by changing the brightness of the lamp. Provides predetermined light to the LCD module.

More specifically, the inverter 210 provides a dimming control signal DIMCON, preferably a tube current control signal 211, which is proportional to or inversely proportional to the dimming voltage.

Here, an inverter that increases the lamp tube current in proportion to the dimming voltage is referred to as a positive dimming inverter, and a case in which the inverter is reversed is referred to as a negative dimming inverter. In this case, in the case of the positive dimming inverter, the luminance increases in proportion to the dimming voltage, and in the case of the negative dimming inverter, the luminance decreases when the dimming voltage increases.                     

The illuminance detecting unit 100 should perform different operations according to the inverter type. That is, when the illuminance detection unit is connected to the positive dimming inverter and the bright ambient illuminance level is detected, the dimming control signal DIMCON is output to increase the dimming voltage, and is connected to the negative dimming inverter, and the bright ambient illuminance level is connected. If this is detected, it should be designed to output a dimming control signal (DIMCON) to lower the dimming voltage.

Next, an example of each of the above-described illuminance sensing units will be described with reference to the accompanying drawings.

FIG. 2A is a circuit diagram illustrating an example of an illuminance detecting unit according to the present invention, and particularly illustrates an example of an illuminance detecting unit for connecting with a positive dimming inverter.

1 and 2A, the illuminance detecting unit 100 according to an embodiment of the present invention may include first and second resistors R1 and R2, a first capacitor C1, and a photo transistor Q1. When the ambient illuminance level is bright, the dimming voltage is supplied to the inverter 210 to increase the brightness level of the lamp 220, thereby minimizing the difference between the ambient brightness level and the brightness level of the liquid crystal display.

In more detail, the photo transistor Q1 according to the present invention receives the power supply voltage AVDD through the first resistor R1 connected to the collector terminal, and the second resistor R2 and the first capacitor C1 are parallel to each other. The base current I_PHOTO according to the peripheral illumination level is received through the connected base terminal, and the first dimming control signal DIMCON1 is output through the emitter terminal.

In operation, when light is irradiated to the base terminal of the photo transistor Q1, the base current I_PHOTO or Ib flows and operates, and since the emitter current increases in proportion to the base current, the dimming control signal DIMCON is represented by the following equation. Equation 1

As shown in Equation 1, a voltage proportional to the photocurrent Ib, which is proportional to the amount of light generated at the base terminal of the photo transistor Q1, that is, a first dimming control signal DIMCON1 is generated.

Spice simulation results of these results are shown in FIG. 2B.

That is, when the peripheral illuminance level of the liquid crystal display becomes bright, and a high level photocurrent occurs, the luminance is increased in the luminance generator 200 using the positive inverter by raising the first dimming control signal DIMCON1 in conjunction with this. The luminance difference between the ambient brightness and the liquid crystal display may be minimized, and the visual fatigue felt by the user may be reduced by the minimized luminance difference.

On the contrary, when the peripheral illuminance level of the liquid crystal display becomes dark and a low level photocurrent occurs, the luminance is decreased in the luminance generator 200 using the positive inverter by lowering the first dimming control signal DIMCON1 in association with the low intensity photocurrent. The luminance difference between the ambient brightness and the liquid crystal display may be minimized, and the visual difference felt by the user may be reduced by the minimized luminance difference.

3A is a circuit diagram for explaining another example of an illuminance detecting unit according to the present invention, and in particular, illustrates an example of an illuminance detecting unit for connecting with a negative dimming inverter.                     

1 and 3A, the illuminance sensing unit 100 according to another embodiment of the present invention may include third and fourth resistors R3 and R4, a second capacitor C2, and a photo transistor Q2. When the ambient illuminance level is bright, the dimming voltage is supplied to the inverter 210 to increase the brightness brightness level of the lamp, thereby minimizing the difference between the ambient brightness level and the brightness level of the liquid crystal display.

In more detail, the photo transistor Q2 according to the present invention receives the power supply voltage AVDD through the third resistor R3 connected to the collector terminal, and the fourth resistor R4 and the second capacitor C2 are paralleled. The second dimming control signal DIMCON2 is output through the connected emitter terminal, and at this time, the second dimming control signal DIMCON2 is adapted to adapt to the base current I_PHOTO according to the ambient illuminance level input through the base terminal. do.

In operation, when light is irradiated to the base terminal of the photo transistor Q2, the base current I_PHOTO or Ib flows to operate the photo transistor Q2.

Since the amount of current flowing through the third resistor R3 is controlled by the amount of collector current of the photo transistor Q1, the second dimming control signal DIMCON2, which is a dimming voltage, changes according to the ambient illuminance level. Equation 2 is as follows.

The above Equation 2 is summarized as Equation 3 below.                     

As mentioned in Equation 3, the second dimming control signal DIMCON2 is generated in inverse proportion to the base current Ib of the photo transistor Q1 which is proportional to the ambient illuminance brightness.

A spice simulation result of these results is shown in FIG. 3B.

That is, when the ambient illuminance level of the liquid crystal display becomes bright, the luminance is increased in the luminance generator 200 using the negative inverter by decreasing the inverter dimming voltage in inverse proportion to the brightness of the liquid crystal display, thereby minimizing the luminance difference between the ambient brightness and the liquid crystal display. In addition, the minimized difference in luminance may reduce visual fatigue that the user feels.

On the contrary, when the ambient illuminance level becomes dark, the luminance is reduced in the luminance generator 200 using the negative inverter by increasing the inverter dimming voltage in proportion thereto, thereby minimizing the luminance difference between the ambient brightness and the liquid crystal display. By minimizing the luminance difference, visual fatigue that a user feels may be reduced.

Although the above has been described with reference to a preferred embodiment of the present invention, those skilled in the art will be able to variously modify and change the present invention without departing from the spirit and scope of the invention as set forth in the claims below. It will be appreciated.

 As described above, according to the present invention, by using the automatic brightness generating device whose brightness is changed according to the ambient illuminance level, it is possible to provide a comfortable display device by minimizing the user's visual fatigue.

Claims (2)

A liquid crystal display device comprising a data driver, a gate driver, and a liquid crystal panel, An illuminance sensor configured to detect a brightness level of the surroundings and output a dimming control signal; And A luminance generator including an inverter and a lamp to provide light having a predetermined brightness to the liquid crystal panel in response to the dimming control signal; Liquid crystal display adapted to the illuminance comprising a. The method of claim 1, wherein the illuminance detection unit, And a photo transistor whose current amount changes in accordance with the ambient illumination level, and outputs a voltage drop amount of a predetermined resistance through which the amplification current of the photo transistor flows as the dimming control signal. .

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