KR101333683B1 - Apparatus lighting LED and method thereof - Google Patents

Abstract

Disclosed are a light emitting device and a method of controlling the light emitting device. The light emitting device includes a compensator for varying and compensating the current detected through the sensing element, and a controller for generating a target output current based on the variable current from the compensator and supplying it to the light source. As a result, the current detected from the sensing element can be variably compensated according to the output current, which is the target current, in order to reduce the offset influence and maintain the normal operation of the sensing element used for the high current LED control.

Light emitting device, LED control, current drive control

Description

Control method of light emitting device and light emitting device

1 is a block diagram of a light emitting device according to an embodiment of the present invention;

2 is a view showing an example of a linear light emitting device according to an embodiment of the present invention;

3 is a view showing an example of a switching type light emitting device according to another embodiment of the present invention;

4 is a flowchart provided to explain a method of operating a light emitting device according to an embodiment of the present invention; and

5 illustrates an example of a light emitting device driven by a plurality of channels according to the present invention.

Explanation of symbols on the main parts of the drawings

100: light emitting device 110: driving unit

120: compensation unit 130: storage unit

140: input unit 150: control unit

160: light source

The present invention relates to a light emitting device and a method of controlling the light emitting device, and more particularly, a light emitting device and a method of controlling the light emitting device which can stably supply a target output current to a light source by compensating for a current detected through a sensing element. It is about.

Solid semiconductor light emitting devices are devices that convert electricity into light, and typical light emitting devices include light emitting diodes (LEDs) and semiconductor lasers (LDs).

Solid-state semiconductor light emitting devices such as light emitting diodes (LEDs) and laser diodes (LDs) include LED backlighting devices and digital lighting processing (DLP) devices using three-color (R, G, B) LEDs with a wide color gamut. Is attracting attention as an element for displaying an image.

In order to improve image quality and reduce power consumption in driving an LED backlight device or a DLP image display device, brightness of the LED is required. There is an analog dimming method (Analog dimming), a typical method of adjusting the brightness of the LED, the analog dimming method is a method of adjusting the brightness of the LED device by changing the magnitude (amplitude) of the current supplied to the LED device.

Changing the amplitude of the PWM pulse using the analog dimming method changes the absolute amount of current supplied to the LED device and changes the wavelength of the light output from the LED device. The chromaticity output through the light emission of the LED device may be adjusted by using the wavelength change of the output light.

However, when the absolute amount of the current to be supplied to the LED device is rapidly changed, the current detected from the sensing element is passed through the operational amplifier or comparator under the influence of the offset voltage in the operation amplifier (OPAMP) or comparator Has a large error with the target output current.

On the other hand, when using a sensing element having a large value in order to reduce the offset effect, if the current to be supplied to the LED element is large, the power of the sensing element is increased, the sensing element does not operate normally.

Accordingly, it is an object of the present invention to variably compensate for the current detected from the sensing element in accordance with the output current, which is a target current, in order to reduce the offset influence and maintain the normal operation of the sensing element used for the high current LED control. The present invention provides a light emitting device and a method of controlling the light emitting device.

According to an aspect of the present invention, there is provided a light emitting device, including: a controller configured to search for a gain value corresponding to a target current, which is a current value to be output, and to output a current command including the gain value; And a compensator for varying and outputting the detected current according to the gain value included in the current command received from the controller.

Preferably, the controller may further include a driver configured to generate and output a target current using the variable current input from the compensator, and control the light source by receiving the target current from the controller. In this case, the compensator may vary and output the detected current by amplifying the current detected through the resistor included in the driver to a gain value.

Also, the storage device may further include a storage unit in which a lookup table including a gain value corresponding to a target current is stored. In this case, the controller may search for a gain value corresponding to the target current in the lookup table by referring to the storage unit.

Also, preferably, the compensator may include at least one resistor and an operational amplifier.

On the other hand, the light emission control method of the present invention comprises the steps of: searching for a gain value corresponding to a target current which is a current value to be output, and outputting a current command including the gain value; And varying and outputting a detected current through a resistor used to drive a light source with the gain value included in the current command.

Hereinafter, with reference to the drawings will be described the present invention in more detail.

1 is a block diagram of a light emitting device according to an embodiment of the present invention. Referring to FIG. 1, the light emitting device 100 includes a driver 110, a compensator 120, a storage 130, an input unit 140, a controller 150, and a light source 160.

As shown in FIG. 2, the driving unit 110 includes a power supply 111, a MOSFET 113, and a resistor 115. The power supply 111 supplies power to the light emitting device 100, the resistor 115 uses a sensing resistor, and the MOSFET 113 provides a target current input from the controller 150 to be described later to the light source 160. do. Here, an example of the light source 160 may be a laser diode or an LED.

The compensator 120 amplifies and outputs the current value detected through the resistor 115 according to the current command received from the controller 150 to be described later.

That is, for example, when the current command received from the controller 150 is 10 times (x10) amplification and the current value detected through the resistor 115 is 1A, the compensator 120 is connected to the resistor 115. The expected target current value 10A, which is a current value obtained by multiplying the detected current value by 10 times according to the current command, is output. In this case, the compensator 120 may output the expected target current value detected using the resistor and the operational amplifier.

The storage unit 130 stores a lookup table in which an amplification factor, that is, a gain value, is amplified for amplifying the current value detected through various programs and resistors 115 required for driving the light emitting device 100. Table 1 below is an example of a lookup table stored in the storage 130.

Target current value (I _ref ) Amplification factor (gain) 0-10A x1 10.01 ~ 20A x10 20.01 ~ 30A x20 30.01-40A x30

Here, the lookup table includes a target current value and an amplification factor corresponding to the target current value input from the user through the input unit 140, and the lookup table is configured to increase the amplification factor as the target current value increases.

When the target current value is input from the input unit 140, the controller 150 searches for the amplification factor corresponding to the target current value from the lookup table by referring to the storage unit 130. The controller 150 outputs a current command including the found amplification factor to the compensator 120.

In addition, the controller 150 generates a target current using either the comparator or the operational amplifier from the expected target current value received from the compensator 120, and outputs the generated target current to the driver 110. Here, the expected target current value is a current value obtained by amplifying the current value detected through the resistor 115 by the amplification factor included in the current command.

2 is a view showing an example of a linear light emitting device according to an embodiment of the present invention.

In FIG. 2, the compensator 120 includes resistors R1, R2, and Rf and associative amplifiers, and the controller 150 controls the current command to manipulate the resistors R1 and R2 according to the input target current. ) To output the expected target current. In this case, the compensator 120 outputs the expected target current by grounding or turning off both the resistors R1 and R2 or by grounding any one of the resistors R1 and R2.

3 is a view showing an example of a switching type light emitting device according to another embodiment of the present invention. In FIG. 2, the compensator 120 outputs the expected target current using the resistors R1 and R2, whereas the compensator 120 outputs the expected target current using the digital variable resistor Rd in FIG. 3.

4 is a flowchart provided to explain a method of operating a light emitting device according to an exemplary embodiment of the present invention. Referring to FIG. 4, when a target current value is input from the input unit 140 (S410: Y), the controller 150 refers to the storage unit 130 to search for an amplification factor corresponding to the target current value from the lookup table. (S420).

Subsequently, the controller 150 outputs a current command including the found amplification factor to the compensator 120 (S430).

The compensator 120 outputs an expected target current value obtained by amplifying the current value detected through the resistor 115 according to the current command input from the controller 15 (S440).

Subsequently, the controller 150 generates and outputs a target current based on the input target target current value (S450).

In detail, the controller 150 generates the target current using either the comparator or the operational amplifier from the expected target current value received from the compensator 120, and outputs the generated target current to the driver 110.

In addition, the driving unit 110 provides the target current received from the controller 150 to the light source 160 to control the light source 160 (S460). That is, the light source 160 outputs the brightness input from the user through the input unit 140. Here, an example of the light source 160 may be a laser diode or an LED.

Meanwhile, the light emitting device according to the present invention can be driven not only by one channel but also by a plurality of channels. FIG. 5 is a view illustrating an example of a light emitting device driven by a plurality of channels according to the present invention, and may be mainly used as an LCD backlight unit.

 On the other hand, in the light emitting device according to the present invention, the compensation unit 120 has been described as outputting the expected target current value using a resistor and the operational amplifier, but is not necessarily limited to this, the compensation unit 120 is a resistor Any means capable of amplifying the current detected through 150 at a desired magnification, i.e., a magnification to make the detected current a target current value, can be used.

On the other hand, in the light emitting device according to the present invention, in the embodiment of the light emitting device shown in Figs. 2, 3, and 5, the input unit and the storage unit are omitted for convenience of description, Figs. 2, 3, and The light emitting device shown in FIG. 5 may include an input unit and a storage unit.

As described above, according to the present invention, it is possible to minimize the occurrence of an irregular error in the output current of the target current by the offset voltage of the operational amplifier or the comparator.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the present invention.

Claims (5)

A controller for searching for a gain value corresponding to a target current which is a current value to be output, and outputting a current command including the gain value; A compensator for varying and outputting the detected current according to the gain value included in the current command received from the controller; And And a storage unit storing a lookup table including a gain value corresponding to the target current. The lookup table is configured such that the gain value increases as the target current increases, The control unit may search for a gain value corresponding to the target current in the lookup table by referring to the storage unit. The method of claim 1, The control unit, Generating and outputting the target current using the variable current input from the compensator, And a driver configured to control the light source by receiving the target current from the controller. The compensation unit, And amplifying the detected current through the resistor included in the driving unit to the gain value to output the variable current. delete The method of claim 1, The compensation unit, Light emitting device comprising at least one resistor and the operational amplifier. By referring to a storage unit having a lookup table including a gain value corresponding to a target current, a search is made for a gain value corresponding to a target current which is a current value to be output from the lookup table, and a current command including the gain value. Outputting; And And varying and outputting a detected current through a resistor used to drive a light source with the gain value included in the current command.

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