KR20060130306A - LCD Display - Google Patents

Abstract

The present invention relates to a liquid crystal display device. A liquid crystal display device according to the present invention includes a plurality of LEDs; An optical sensor for detecting illuminance of light; It includes a power supply for adjusting the number of the LED is turned on according to the signal of the optical sensor according to the illuminance of the light. As a result, a liquid crystal display device having excellent visibility outdoors is provided.

Description

Liquid Crystal Display {LIQUID CRYSTAL DISPLAY}

1 is a control block diagram of a liquid crystal display device according to a first embodiment of the present invention;

2 is a control block diagram of a liquid crystal display according to a second embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: optical sensor 200: power supply

210: detection unit 220, 225: selection unit

230: boosting unit 240: control unit

241 diode 300 LED

310, 315: first LED unit 320, 325: second LED unit

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal display device, and more particularly, to a liquid crystal display device having improved degradation of visibility due to external light.

The liquid crystal display device includes a liquid crystal panel in which liquid crystal is injected between the thin film transistor substrate and the color filter substrate. Since the liquid crystal display is a non-light emitting device, a backlight unit for supplying light may be disposed on the rear surface of the thin film transistor substrate. The amount of light emitted from the backlight is adjusted according to the arrangement of liquid crystals.

The liquid crystal display may be classified into a transmission type and a reflection type according to the shape of the light source. In the related art, a transmissive type in which a backlight is disposed on a rear surface of a liquid crystal panel and light from the backlight passes through the liquid crystal panel has been generally used. However, the transmissive type has a problem in that power consumption is high, and the liquid crystal display device becomes heavy and thick. In particular, with the development of portable communication devices, a light and thin reflective liquid crystal display device, which consumes less power, is drawing attention. Using a reflective liquid crystal display device can limit the use of the backlight, which occupies about 70% of the power consumption, thereby reducing power consumption.

The transflective liquid crystal display device utilizes the advantages of two types, the transmissive type and the reflective type. Reflective areas for reflecting external light and transmissive areas for transmitting light from the backlight are provided to ensure proper luminance according to the use environment. In the case of the transflective liquid crystal display device, the visibility is improved by about 10 to 20% in the outdoors, and the optical characteristics are excellent in the contrast ratio, the transmission mode and the reflection mode of the liquid crystal panel.

However, such a transflective liquid crystal display has problems of cost increase and fabrication for process addition such as an organic film and a reflective film, and visibility is reduced as much as reflectance in a room than a transmissive liquid crystal display.

Accordingly, an object of the present invention is to provide a transmissive liquid crystal display device having excellent visibility even outdoors.

The object is a plurality of LEDs according to the present invention; An optical sensor for detecting illuminance of light; It is achieved by a power supply for adjusting the number of the LED is turned on according to the signal of the optical sensor according to the illuminance of the light.

The power supply unit, the sensing unit for detecting a signal according to the illuminance of the light from the optical sensor; A selection unit for selecting the LED to be turned on; A booster which boosts an input power and outputs the LED; It may include a control unit for controlling the selection unit to adjust the LED turned on in accordance with the signal sensed by the detection unit.

The control unit controls the selection unit to increase the number of LEDs that are turned on as the illumination intensity increases, and the number of LEDs that are turned on has a proportional relationship with the illumination intensity, so that the influence of external light increases. As the number of LEDs turned on increases, the number of light sources that provide light to the liquid crystal panel increases. Therefore, even if the liquid crystal display is located outdoors and is affected by external light, visibility is improved.

The controller controls the selector to turn on a predetermined number of LEDs when the signal is not detected from the detector. That is, when there is no influence on the external light, a predetermined LED is turned on to provide light to the liquid crystal panel, and as described above, the number of LEDs turned on when the influence of the external light is increased.

The optical sensor may be provided as a photodiode, and it is preferable that the optical sensor is a photodiode that increases the magnitude of the current conducted as the light intensity increases.

The power supply unit may include a boosting switching regulator or a boosting charge pump. When the power supply includes a boosting switching regulator, the LEDs are connected in series with each other, and the power supply unit boosts the boosting pump. When included, the LEDs are connected in parallel to each other.

The liquid crystal panel may further include a liquid crystal panel provided with light from the LED, and the liquid crystal panel may have a transmissive area for transmitting the light. The present invention provides a transmissive type having only a transmissive area in a transflective or reflective liquid crystal display device. It is preferable to apply to a liquid crystal panel.

Hereinafter, the present invention will be described with reference to the accompanying drawings.

In various embodiments, like reference numerals refer to like elements, and like reference numerals refer to like elements in the first embodiment and may be omitted in other embodiments.

1 is a control block diagram of a liquid crystal display according to a first embodiment of the present invention. As shown in the drawing, the liquid crystal display includes an optical sensor 100, a power supply unit 200, and a plurality of LEDs 300. The liquid crystal display according to the present embodiment is described as an example that is used in a portable small terminal, such as a portable telephone or personal digital assistants (PDAs) which are frequently used outdoors, as well as indoors, and easy to carry. The range is not limited to this.

The optical sensor 100 detects ambient light and outputs a signal according to the illuminance of the light to the power supply unit 200 on the driving circuit board (not shown). The optical sensor 100 is preferably provided with a photodiode as a light receiving element. The photodiode is a semiconductor device that receives a light and generates a current. As the light intensity increases, the photodiode increases the magnitude of the conducted current. As such, the signal according to the illuminance of the light output from the optical sensor 100 is a current, and the greater the amount of received light, the greater the amount of current generated. The optical sensor 100 is exposed to any part of the portable telephone or PDA so as to receive external light.

The plurality of LEDs 300 are components included in a backlight unit (not shown) that receives power from the power supply unit 200 and provides light to the liquid crystal panel (not shown). The LED 300 may be formed on the front surface of the liquid crystal panel rear surface, or may be formed along one side of the rear surface of the liquid crystal panel. LED 300 is preferably composed of one red LED, one blue LED and a pair of green LEDs to supply white light.

The LED 300 includes two LED units 310 and 320 connected in parallel. The LED units 310 and 320 may include a first LED unit 310 including four LEDs and a second LED unit 320 including three LEDs. The turn on and turn off of the LED is performed in units of the LED units 310 and 320. In other words, the plurality of LEDs constituting each of the LED units 310 and 320 may be simultaneously turned on or turned off by a driving power source. In the liquid crystal display according to the present invention, the first LED unit 310 and the second LED are generally turned on only when the first LED unit 310 is turned on in a room which is not affected by external light, and visibility is reduced by sunlight or the like outdoors. All of the units 320 are turned on.

The number of LED units 310 and 320 that are units of turn on / turn off and the number of LEDs included in one LED unit 310 or 320 may be variously modified according to the size and required visibility of the liquid crystal panel. .

The power supply unit 200 includes a detector 210 for detecting a signal according to the illuminance of the light from the optical sensor 100, a selector 220 for selecting the LED units 311 and 320 to be turned on, and an input power source. It includes a booster 230 for boosting the output to the LED 300 and a control unit 240 for controlling the mechanism for generating the overall drive power.

The sensing unit 210 detects a signal according to the illuminance of the light from the optical sensor 100 and senses a current generated by external light as described above.

The booster 230 boosts the input external power supply Vcc and supplies it to the LED units 310 and 320. Since the LED units 310 and 320 of the present embodiment are connected in parallel, a voltage of a predetermined magnitude is applied to the anode electrode of the LED 300. When the LEDs 300 are connected in parallel, the power supply unit 200 may be provided as a boosting charging pump, and the boosting unit 230 may include a plurality of capacitors (not shown) connected in parallel. .

The selector 220 selects the LED units 310 and 320 turned on under the control of the controller 240 so that the driving power output from the booster 230 is selectively provided to the LED units 310 and 320. . The selector 220 of the present embodiment selects the LED units 310 and 320 in a manner of being connected to the cathode electrode of the LED 300 to form a voltage difference with the voltage applied from the booster 230. In order for a current to flow in the LED 300, a voltage difference must be generated between the cathode electrode and the anode electrode of the LED 300. Since a predetermined voltage is applied to the anode electrode of the LED 300 from the boosting unit 230, the selector 220 applies a voltage having the same level as that applied to the anode electrode to the cathode electrode of the LED 300, thereby providing current. Does not flow or applies a lower level voltage to flow the current. As a result, the LED units 310 and 320 through which current flows are turned on, and the LED units 310 and 320 through which current does not flow are turned off. The selection unit 220 selecting the LED units 310 and 320 to be turned on is just one example, and its configuration may be variously modified. A power supply boosted by the booster 230 may be selectively output by connecting a switching element to each of the LED units 310 and 320 and controlling on / off of switching.

The controller 240 controls an overall mechanism in which driving power is applied to the LED units 310 and 320. The controller 240 controls the booster 230 to boost the input power Vcc to supply the LED units 310 and 320, and the signal according to the illuminance of the light detected by the detector 210, that is, the current. The selector 220 is controlled to select the LED units 310 and 320 to which the driving power is to be supplied according to the amount. The controller 240 controls the selector 240 to turn on the first LED unit 310 when the detector 210 does not detect a current. That is, the first LED unit 310 is always turned on even when the light sensor 100 does not sense the illuminance of the light because there is no influence of external light. The number of LEDs included in the first LED unit 310 is provided as an appropriate number for supplying light to the liquid crystal panel when there is no influence on external light.

The controller 240 according to the present invention controls the selection unit 220 such that the number of LEDs 300 turned on increases as the light intensity increases, and the controller 240 according to the present embodiment has a current of a predetermined magnitude or more. If detected, the selector 220 is controlled to turn on the second LED unit 320. As the light intensity increases, that is, when the visibility of the liquid crystal panel decreases due to outdoor sunlight or the like, the number of LEDs turned on is increased to improve visibility. In summary, the control unit 240 turns on a predetermined number of LEDs when the visibility of the liquid crystal panel is not a problem due to low illuminance of the external light, and when the visibility of the liquid crystal panel is required due to effects such as sunlight, To increase the number. The relationship between the illuminance of the external light and the number of LEDs to be turned on may be represented by a proportional function, and there is a predetermined number of LEDs that are always turned on even when no external light is detected.

2 is a control block diagram of a liquid crystal display according to a second exemplary embodiment of the present invention, and as shown, the LED 300 includes a first LED unit 315 and a second LED unit 325 connected in series. do. Except for the connection of the LED units 315 and 325, since most of the components are the same as the first embodiment shown in Fig. 1, duplicate description thereof will be omitted.

One end of the LED units 315 and 325 is connected to the ground end, and a capacitor for stabilization is connected between the other end and the ground end. When the LEDs 300 are connected in series, the power supply unit 200 may be provided as a boosting switching regulator, and the boosting unit 230 may include a plurality of coils (not shown) connected in series. . The diode 241 connected between the power supply unit 200 and the LED 300 is for supplying a boosted current in the coil. The boosting switching regulator has an advantage that the efficiency is good and the constant current is supplied to the LED 300 so that the brightness of the LED 300 is almost constant.

Power boosted by the booster 230 is supplied to the first LED unit 315 or the second LED unit 325 by the selector 225. The selector 225 includes a switching element that is turned on / off to supply or cut off power, and the switching element is connected to each of the LED units 315 and 325.

The controller 240 controls the switching element of the selector 225 according to the signal for the illuminance of the light detected by the detector 210. That is, when the detection unit 210 does not detect the signal of the illuminance of the light, that is, the current, only the switching element connected to the first LED unit 315 is switched to supply power, and when the external light is detected. All of the switching elements connected to the first and second LED units 315 and 325 are switched to supply power to all the LEDs.

According to another embodiment of the present invention, even in the case of a liquid crystal display device using a light source such as a non-LED lamp, it is possible to adjust the number of lamps turned on by determining the illuminance of the external light. In the case of a liquid crystal display device which is easy to carry and is used both indoors or outdoors, visibility is reduced by external light, so that it is obvious that a power supply unit for selectively driving the optical sensor and the light source of the present invention may be applied to compensate for this.

Although some embodiments of the invention have been shown and described, those of ordinary skill in the art will recognize that the present invention increases the number of light sources turned on with external light without departing from the principles or spirit of the invention. It will be appreciated that embodiments may be modified. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

As described above, according to the present invention, a liquid crystal display device having excellent visibility outdoors is provided.

Claims (9)

A plurality of LEDs; An optical sensor for detecting illuminance of light; And a power supply for adjusting the number of LEDs turned on according to the signal of the optical sensor according to the illuminance of the light. The method of claim 1, The power supply unit, A detector for detecting a signal according to the illuminance of the light from the optical sensor; A selection unit for selecting the LED to be turned on; A booster which boosts an input power and outputs the LED; And a controller configured to control the selection unit to adjust the LED turned on according to the signal sensed by the detection unit. The method of claim 2, And the controller controls the selector to increase the number of LEDs turned on as the light intensity increases. The method of claim 2, And the controller controls the selector to turn on a predetermined number of LEDs when the signal is not detected from the detector. The method of claim 1, The optical sensor is a liquid crystal display, characterized in that provided with a photodiode. The method of claim 1, The power supply unit includes a boosting switching regulator or a boosting charge pump. The method of claim 6, And the power supply unit includes a boosting switching regulator, and the LEDs are connected in series with each other. The method of claim 6, The power supply unit includes a boosting charge pump, wherein the LEDs are connected in parallel to each other. The method of claim 1, Further comprising a liquid crystal panel receives light from the LED, And the liquid crystal panel includes a transmission area for transmitting the light.

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