KR100820355B1 - LED Drive Unit by Taking External Illumination into Consideration and Method Therefor - Google Patents

Abstract

The present invention relates to an LED driving apparatus and an LED control method for the same considering the external illuminance.

The present invention provides an illuminance detecting means for measuring and transmitting an illuminance value by sensing an intensity of external light; A memory for storing a drive current table representing a drive current according to a range of illuminance values and a drive current control program for adjusting the drive current according to the illuminance value; An LED panel in which a plurality of LEDs are connected in series or in parallel to emit light according to a driving current; And LED control means for measuring external illuminance through the illuminance sensing means and controlling an amount of driving current supplied to the LED panel according to the measured illuminance value.

According to the present invention, it is possible to output the light or color of the appropriate brightness according to the brightness of the ambient light by measuring the ambient illuminance in a display device such as an LCD, and to secure visibility through the contrast of the colors.

Light, Colors, Illuminance, Brightness, Contrast, Visibility, LED, Contrast

Description

LED drive device considering external illumination and LED control method {LED Drive Unit by Taking External Illumination into Consideration and Method Therefor}

1 is a block diagram schematically showing an LED driving device considering external illumination according to a preferred embodiment of the present invention;

2 is an exemplary view showing a driving current table in accordance with a preferred embodiment of the present invention;

3 is a flowchart illustrating an LED control method considering external illumination according to a preferred embodiment of the present invention.

<Description of Symbols for Main Parts of Drawings>

100: LED driving device 110: illuminance detection unit

120: memory 130: LED control unit

132: main controller 134: red control unit

136: green control part 138: blue control part

140: LED panel 142: red LED array

144: green LED array 146: blue LED array

The present invention relates to a light emitting diode (LED) driving apparatus in consideration of external illumination and an LED control method therefor. More specifically, after detecting the external illuminance using an illuminance detector, the LED driving device and the LED control for the external illuminance by controlling the drive current driving the LED emitting a plurality of colors of light according to the illuminance It is about a method.

As electronic and communication technologies have developed, most electronic and communication devices have been miniaturized and lightweight. In addition, with the advent of the multimedia era, information that can be visually confirmed, such as an image and a video, is gaining attention, not merely information such as voice and text. Therefore, most of the recently released electronic and communication devices have a display unit that can check information with time. Recently, display devices are cathodic ray tubes (CRTs), memory displays, plasma displays, liquid crystal displays (LCDs), electroluminescence (EL), LEDs, and electrochromic displays (ECDs).

Among these, the LED is recognized as a next-generation light source because it is excellent in energy saving effect and can be used semi-permanently compared to the light sources of other display devices described above. In addition, in recent years, the problem of low brightness of the LED has been greatly improved, and the application market using the LED has spread to the entire industry, thereby foreseeing the full-scale LED era.

In addition, LEDs have recently been used as the main light source of mobile devices such as mobile phones. LED is used as the main light source of mobile devices such as cell phones, digital cameras, PDAs (Personal Digital Assistants), and white using red (R), green (G), and blue (B) colors depending on the color of the keypad of the mobile device. As LED is used as a backlight light source of LCD which is mainly used as a display device of mobile, the demand for this is exploding.

LCDs themselves do not emit light, so a back light source is needed. That is, an LCD screen is output by placing a backlight device as a light source that emits light behind the LCD panel and passing light output from the backlight device through the LCD panel.

On the other hand, the LCD screen typically maintains a constant screen brightness or a set screen brightness and color regardless of the brightness of the outside, that is, the light of the outside of the LCD panel, and regardless of external environmental changes. In other words, the LCD using a conventional LED backlight device is a day and place, such as an outdoor environment in which a bright light is generated by the sun, a night environment in a dark brightness, an indoor environment in which a constant brightness is maintained by various lighting devices such as a fluorescent lamp and an incandescent lamp. It does not respond to changes in the environment caused by the light and outputs the screen with the brightness and color of the set light.

Therefore, a user using the electronic device equipped with the above-described LCD distinguishes colors due to strong sunlight in an outdoor bright environment where a dark LCD screen may not recognize light and colors well in a dark place or a very bright light is generated. There is a problem in that an LCD screen that outputs bright light and bright colors cannot be seen.

In order to solve this problem, the present invention, after detecting the external illuminance using an illuminance detector, LED driving device considering the external illuminance by controlling the drive current for driving the LED emitting light of a plurality of colors according to the illuminance And to provide a method for controlling the LED for this purpose.

In order to achieve the above object, the present invention provides a light emitting device using an LED, comprising: illuminance sensing means for measuring and transmitting an illuminance value by sensing an intensity of external light; A memory for storing a drive current table representing a drive current according to a range of illuminance values and a drive current control program for adjusting the drive current according to the illuminance value; An LED panel in which a plurality of LEDs are connected in series or in parallel to emit light according to a driving current; And LED control means for measuring external illuminance through the illuminance sensing means and controlling an amount of driving current supplied to the LED panel according to the measured illuminance value.

In addition, according to another object of the present invention, in the light emitting method using the LED, (a) measuring the illumination value by sensing the intensity of the external light; (b) determining a driving current according to the illuminance value; And (c) supplying a driving current to the plurality of LEDs to adjust the brightness or contrast of light to provide an LED control method in consideration of external illuminance.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. First of all, in adding reference numerals to the components of each drawing, it should be noted that the same reference numerals have the same reference numerals as much as possible even if displayed on different drawings. In addition, in describing the present invention, when it is determined that the detailed description of the related well-known configuration or function may obscure the gist of the present invention, the detailed description thereof will be omitted.

The present invention can be utilized in a backlight unit (BLU) using an LED. Therefore, the present invention can be used as a light source of an LCD (Liquid Crystal Display) of an electronic device such as a mobile communication terminal, a digital camera, an MP3 player.

1 is a block diagram schematically illustrating an LED driving device considering external illumination according to a preferred embodiment of the present invention.

LED driving device 100 in consideration of the external illumination according to a preferred embodiment of the present invention includes an illumination sensor 110, memory 120, LED controller 130 and LED panel (Panel) (140).

The illuminance detecting unit 110 is an illuminance detecting means such as an illuminance detecting sensor that measures and outputs the intensity of light outside the aforementioned electronic device, that is, illuminance, to generate and transmit an illuminance value proportional to the illuminance as an electric signal.

The memory 120 is an LED driving program for driving the LED panel 140 to emit light and storage means for storing various data therefor. In addition, the memory 120 according to a preferred embodiment of the present invention is controlled according to a drive current control program and a range of illuminance for controlling the drive current supplied to the plurality of LEDs of the LED panel 140 according to the external illumination. The drive current table corresponding to the current value of the drive current to be stored is stored. Here, the driving current table will be described in detail with reference to FIG. 2 in a process to be described later.

The LED controller 130 is an LED control means for controlling the overall operation of the LED driving apparatus 100. The LED controller 130 supplies a driving current to the LED panel 140 according to a driving current control program, thereby causing the LED panel 140 to emit a constant light and Let's print out the color.

LED control unit 130 according to a preferred embodiment of the present invention includes a main control unit 132 and a plurality of color control unit, and periodically controls the illuminance detection unit 110 to measure the external illuminance and the measured illuminance value When received, the driving current corresponding to the illuminance value measured in comparison with the driving current table stored in the memory 120 is checked and the corresponding current is supplied to the LED panel 140 so that the LED panel 140 is applied to the external illuminance. Control to output appropriate light and color.

In FIG. 1, only the red control unit 134, the green control unit 136, and the blue control unit 138 are illustrated as a plurality of color control units, but may include a control unit for controlling other colors. However, hereinafter, it will be assumed that the color control unit includes only the red control unit 134, the green control unit 136, and the blue control unit 138 for convenience of description.

Here, the main controller 132 measures the illuminance by controlling the illuminance detecting unit 110 and the memory 120, and controls each of the color control units such as the red control unit 134, the green control unit 136, and the blue control unit 138. It is the main control means for controlling to supply the driving current corresponding to the measured illuminance value to the LED panel 140, respectively. At this time, the main controller 132 detects the driving current corresponding to the illuminance value measured using the driving current table.

The red control unit 134, the green control unit 136, and the blue control unit 138 control the red LED unit 142, the green LED unit 144, and the blue LED of the LED panel 140, respectively, under the control of the main controller 132. Supplying a driving current to the unit 146 is a color control means for controlling each LED unit to output a constant light and color.

To this end, the main control unit 132 is a red control unit 134, the green control unit 136 and the blue control unit 138, respectively, the red LED unit 142, green LED unit 144 connected to the same or different driving current, respectively ), The blue LED unit 146 is supplied to control the LED panel 140 emits various colors.

The LED panel 140 includes a red LED array 142, a green LED array 144, and a blue LED array 146, in which the LEDs of each LED array are connected in series or in parallel to the red, green, and blue light. It emits light, and it is a light emitting means using LED which outputs seven colors of red, green, blue, yellow, magenta, cyan, and white.

Here, the red LED array 142, green LED array 144, blue LED array 146 is composed of an LED array in which a plurality of LEDs are connected in series or in parallel, each LED array is a red control unit 134, green The controller 136 is connected to the blue controller 138 to receive driving currents from each controller to emit red, green, and blue light.

2 is an exemplary view showing a driving current table in accordance with a preferred embodiment of the present invention.

The main control unit 132 compares the measured illuminance value with the driving current table to check the driving current value corresponding to the illuminance value, and controls the red control unit 134, the green control unit 136, and the blue control unit 138, respectively. To increase or decrease the driving current supplied to the red LED array 142, the green LED array 144, and the blue LED array 146 by the identified driving current value. Therefore, the driving current table according to the preferred embodiment of the present invention corresponds to a table corresponding to the increase and decrease of the driving current according to a predetermined range of the illuminance value.

The main control unit 132 controls the red control unit 134, the green control unit 136, and the blue control unit 138 to decrease the driving current by 5 mA when the illuminance value is 10000 Lux or more. That is, when the illuminance value is more than 10000 Lux, the main control unit 132 determines that the surrounding environment is a very bright outdoor environment, and reduces the driving current of each control unit equally, thereby increasing the brightness of the light emitted from the LED panel 140. Decreases.

In addition, when the illuminance value is less than 10000 Lux to 500 Lux or more, the main control unit 132 determines that the surrounding environment is a bright daytime outdoor environment or an environment under a fluorescent lamp in the room to maintain the brightness at the current state. The driving current of the green control unit 144 remains the same, but the blue control unit 146 controls the driving current to increase by 5 mA to adjust the contrast of colors to ensure visibility. Adjust the gamma curve of to blue.

In addition, when the illuminance value is less than 500 Lux to 5 Lux or more, the main controller 132 determines that the surrounding environment is an indoor fluorescent lamp or a slightly dark environment at night, and maintains the brightness in the present state. The driving current of 146 is kept the same, but in order to ensure visibility by highlighting the contrast of colors, the red control unit 146 is controlled to increase the driving current by 5 mA to adjust the gamma curve of the screen to the red side. . Here, in the bright environment, the gamma curve is adjusted to the blue side, and in the dark environment, the gamma curve is adjusted to the red side, which is advantageous to ensure visibility.

In addition, when the illuminance value is less than 5 Lux, the main controller 132 determines that the surrounding environment is a very dark environment at night, and causes the red control unit 134, the green control unit 136, and the blue control unit 138 to respectively drive the driving current. By controlling the increase by 5 mA, the driving current of each control unit is equally reduced to increase the brightness of light emitted from the LED panel 140.

The driving current table described above is merely illustrative, and the range of the illuminance value and the numerical value of the increase and decrease of the driving current of each control unit may be changed and may be set differently according to the characteristics of the surrounding LED driver.

3 is a flowchart illustrating an LED control method considering external illumination according to a preferred embodiment of the present invention.

LED driving device 100 is mainly attached to the rear of the LCD that outputs the screen is used as a rear light source of the LCD. When the LCD is driven to supply power to the LED driver 100, the LED driver 100 may be configured as the red LED array 142, the green LED array 144, and the blue LED array 146 of the LED panel 140, respectively. The red, green, and blue light is emitted from the red, green, and blue light to be mixed so that the LED panel 140 emits white light.

Thereafter, the LED driving apparatus 100 measures the peripheral illuminance using the illuminance detecting unit 110 provided (S310), and compares the measured illuminance value with the driving current table stored in the memory 120. Check the drive current value corresponding to (S320). That is, the LED driving apparatus 100 confirming the driving current value checks whether the illumination value corresponds to which range of each range of the driving current table. First, the LED driving apparatus 100 checks whether the illuminance value is 10000 Lux or more (S330).

When the LED driving apparatus 100 confirms that the illuminance value is 10000 Lux or more, the LED driving apparatus 100 causes the red control unit 134, the green control unit 136, and the blue control unit 138 to display each LED array of the LED panel 140. The brightness of light emitted from the LED panel 140 is reduced by controlling the driving currents supplied to the red LED array 142, the green LED array 144, and the blue LED array 146 to be equally reduced by 5 mA, respectively. (S340).

In addition, the LED driving device 100 checks whether the illuminance value is less than 10000 Lux to 500 Lux or more when the illuminance value is not 10000 Lux or more (S350). When the LED driving device 100 confirms that the illuminance value is less than 10000 Lux to 500 Lux or more as a result of checking in step S350, the LED driving device 100 maintains the driving current supplied from the red control unit 134 and the green control unit 136 to the LED panel 140. The driving current supplied from the blue control unit 138 is increased by 5 mA to adjust the gamma curve toward the blue side to adjust the contrast of the color to secure visibility (S360).

In addition, the LED driving apparatus 100 checks whether the illuminance value is less than 500 Lux to 5 Lux or more when the illuminance value is not less than 10000 Lux to 500 Lux or more (S370). As a result of checking in step S370, the LED driving apparatus 100 maintains the driving current supplied from the green control unit 136 and the blue control unit 138 to the LED panel 140 when the illuminance value is less than 500 Lux to 5 Lux or more. However, by increasing the driving current supplied from the red control unit 134 by 5 mA to adjust the gamma curve toward the red to adjust the contrast of the color to secure visibility (S380).

In addition, when the LED driving device 100 confirms that the illuminance value is less than 5 Lux as a result of checking in step S370, the LED panel 140 is controlled from each control unit, that is, the red control unit 134, the green control unit 136, and the blue control unit 138. Emitting light from the LED panel 140 by controlling the driving currents supplied to each of the LED arrays ie, the red LED array 142, the green LED array 144, and the blue LED array 146 to increase by 5 mA, respectively. Increase the brightness of the light (S390). As a result, the LED driving apparatus 100 may reduce or increase the brightness of the light according to the ambient illumination and secure visibility.

In FIG. 3, a preferred embodiment of the present invention has been described using the numerical values of the driving current table described with reference to FIG. 2. However, as described above, these figures are by way of example only, and the present invention is not limited to these figures. In addition, although the range of illuminance values is set in four ranges as described with reference to FIG. 2 in FIG.

That is, the present invention is an invention used to measure the illumination value of the ambient light to adjust the contrast of the brightness and color of the light output from the LED driver 100 according to the illumination value, the illumination value is a plurality of two or more It is possible to secure visibility by adjusting the contrast of colors by adjusting the brightness of light and adjusting the gamma curve by increasing or decreasing the supply current supplied from each color control part to each LED part according to each range. will be.

The above description is merely illustrative of the technical idea of the present invention, and those skilled in the art to which the present invention pertains may make various modifications and changes without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention but to describe the present invention, and the scope of the technical idea of the present invention is not limited by these embodiments. The protection scope of the present invention should be interpreted by the following claims, and all technical ideas within the equivalent scope should be interpreted as being included in the scope of the present invention.

As described above, according to the present invention, a display device such as an LCD may measure ambient illumination and output light or color having an appropriate brightness according to the brightness of the surrounding light, and display visibility through color contrast. It can be secured.

Claims (13)

In the light emitting device using the LED, Illuminance sensing means for sensing and transmitting an illuminance value by sensing an intensity of external light; A memory for storing a drive current table representing a drive current according to a range of the illuminance value and a drive current control program for adjusting the drive current according to the illuminance value; A plurality of LED panels connected in series or in parallel to emit light according to the driving current; And LED control means for measuring the external illuminance through the illuminance detecting means and controlling the amount of driving current supplied to the LED panel according to the measured illuminance value LED driving device in view of the external illuminance comprising a. The method of claim 1, wherein the LED panel, LED driving apparatus in consideration of the external illumination, characterized in that the plurality of LEDs emitting the same color of the LED comprises a plurality of color LED array (Array) connected in series or in parallel. The method of claim 2, wherein the plurality of color LED array, LED driver with external illuminance comprising red LED array, green LED array and blue LED array. The method of claim 2, wherein the LED control means, A plurality of color control means connected to the plurality of color LED arrays one-to-one to supply the driving current to each color LED array; And And external control means for measuring the external illuminance using the illuminance sensing means and determining the driving current to control the color control unit to supply the driving current to the color LED array. LED driver considering the. The method of claim 4, wherein the main control means, The LED driving apparatus in consideration of external illuminance by using the driving current table to adjust the brightness of the light by the respective color control means to increase or decrease the driving current by the increment by the same according to the illuminance value. The method of claim 4, wherein the main control means, The light is generated by causing one of the plurality of color control means to increase the drive current by only an increment by an increase and decrease according to the illuminance value using the drive current table, and to allow the remaining color control means to maintain the drive current. LED driver considering the external illumination, characterized in that to adjust the contrast (contrast) of the color. delete In the light emission method using LED, (a) measuring the illuminance value by sensing the intensity of external light; (b) determining a driving current according to the illuminance value; And (c) supplying the driving current to the plurality of LEDs to adjust contrast or brightness of light of the LEDs; The drive current is determined by checking the drive current corresponding to the illuminance value in a drive current table including the drive current corresponding to a plurality of ranges in which illuminance is divided into a predetermined range in step (b). LED control method considering the external illuminance, characterized in that. The method of claim 8, wherein step (c) comprises: (c1) when the illuminance value falls within the first range, reducing the brightness of the light by supplying the plurality of colors of light equally to the plurality of LEDs; (c2) when the illuminance value is within the second range, increase the light of one color of the light of the plurality of colors, maintain the same light of the remaining colors, and supply the same to the plurality of LEDs. Adjusting the control; And (c3) if the illuminance value is within the third range, increasing the brightness of the light by increasing the light of the plurality of colors equally and supplying the light to the plurality of LEDs; LED control method considering the external illuminance comprising a. The method of claim 9, The first range is more than 10000 Lux, the second range is more than 5 Lux 10000 Lux, the third range is less than 5 Lux LED control method in consideration of external illuminance. The method of claim 9, wherein step (c2), (c11) When the illuminance value corresponds to the 2-1 range of the second range, the gamma curve is increased by increasing the light of the blue color among the lights of the plurality of colors and keeping the light of the remaining colors the same. Adjusting the contrast of the color by supplying the plurality of LEDs by adjusting a curve toward blue; and (c12) when the illuminance value falls within the second range of the second range, the gamma curve is increased by increasing the light of the red color among the lights of the plurality of colors and keeping the light of the remaining colors the same. Adjusting the contrast of the color by supplying to the plurality of LEDs by adjusting to the red direction LED control method considering the external illuminance comprising a. The method of claim 11, The 2-1 range is 500 Lux or more and less than 10000 Lux, and the 2-2 range is 5 Lux or more and less than 500 Lux in consideration of external illuminance. The method of claim 8, wherein the plurality of ranges of the division criteria, LED control method in consideration of the external illumination, characterized in that the range of the illumination divided according to one or more of whether it is day or night or indoors or outdoors.

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