KR20110138754A - Light unit and method for driving the same - Google Patents

Abstract

PURPOSE: A light unit and a driving method are provided to improve reliability by maintaining constant brightness for a long time. CONSTITUTION: A light unit comprises a plurality of light emitting devices(12), a driving part(30), an optical sensor(20), a controller(40), and a alarm signal generator(50). The driving part applies a driving current to a plurality of light emitting devices. The optical sensor senses the light which is emitted from the plurality of the light emitting devices and converts a sensed result into a voltage value. The controller compares the voltage value with a reference voltage value and generates the size control signal and current deviation signal of the driving current. The alarm signal generator generates an alarm signal when the current deviation signal offered from the controller has over a predetermined value.

Description

LIGHT UNIT AND METHOD FOR DRIVING THE SAME

An embodiment relates to a light unit and a driving method thereof.

Light emitting diodes (LEDs) are a type of semiconductor device that converts electrical energy into light. Light emitting diodes have the advantages of low power consumption, semi-permanent life, fast response speed, safety and environmental friendliness compared to conventional light sources such as fluorescent and incandescent lamps. Accordingly, many researches are being conducted to replace existing light sources with light emitting diodes, and the use of light emitting diodes is increasing as a light source for light units such as various lamps, display devices, electronic signs, and street lamps that are used indoors and outdoors.

Meanwhile, the light emitting diode may change in brightness and color depending on an external environment such as time and temperature. Therefore, various methods for maintaining the brightness and color of light emitting diodes by minimizing such changes have been studied.

The embodiment provides a light unit and a driving method thereof for keeping the luminance constant for a long time.

The embodiment provides a light unit having improved reliability and a driving method thereof.

The light unit according to the embodiment includes a plurality of light emitting elements; A driving unit applying a driving current to the plurality of light emitting devices; An optical sensor that detects light emitted from the plurality of light emitting elements and converts the sensing result into a voltage value; A controller configured to control the magnitude of the drive current by comparing the voltage value with a pre-stored reference voltage value and generate a current deviation signal comparing the magnitude of the drive current with a magnitude of the pre-stored reference drive current; And a warning signal generator for generating a warning signal when the current deviation signal provided from the controller has a predetermined value or more.

In one embodiment, a light unit driving method includes: emitting light by a plurality of light emitting devices by a driving current applied from a driver; An optical sensor detecting the light and converting the detection result into a voltage value; A control unit generating a control signal by comparing the voltage value with a previously stored reference voltage value, and generating a current deviation signal by comparing the magnitude of the driving current with the magnitude of a reference driving current; Controlling the magnitude of the driving current using the control signal in the driver; And generating a warning signal when the current deviation signal is greater than or equal to a predetermined value by the warning signal generator.

The embodiment can provide a light unit and a driving method thereof for keeping the luminance constant for a long time.

The embodiment can provide a light unit having improved reliability and a method of driving the same.

1 is a view showing a light unit according to an embodiment
2 is a flowchart illustrating a method of driving a light unit according to an embodiment.

In the description of the embodiments, it is to be understood that each layer (film), region, pattern or structure is formed "on" or "under" a substrate, each layer The terms " on "and " under " encompass both being formed" directly "or" indirectly " In addition, the criteria for the top or bottom of each layer will be described with reference to the drawings.

In the drawings, the thickness or size of each layer is exaggerated, omitted, or schematically illustrated for convenience and clarity of description. In addition, the size of each component does not necessarily reflect the actual size.

Hereinafter, a light unit and a driving method thereof according to embodiments will be described with reference to the accompanying drawings.

1 is a view showing a light unit according to an embodiment.

Referring to FIG. 1, a light unit according to an embodiment includes a plurality of light emitting elements 12 generating light, a driving unit 30 applying a driving current CC to the plurality of light emitting elements 12, and The optical sensor 20 which detects light emitted from the plurality of light emitting elements 12 and converts the sensing result into a voltage value SS, and compares the voltage value SS with a pre-stored reference voltage value to drive the light. A controller 40 for generating a control signal CS for controlling the magnitude of the current CC and a current deviation signal CDS comparing the magnitude of the driving current CC with a magnitude of a reference driving current stored in advance; It may include a warning signal generator 50 for generating a warning signal (ES) when the current deviation signal (CDS) provided from the controller 40 has a predetermined value or more.

The light unit according to the embodiment may self-correct the luminance and the color of the light of the plurality of light emitting elements 12 by including the optical sensor 20. The self-correction function may be performed by the control signal CS generated by the controller 40. The control signal CS may be formed by comparing the voltage value SS generated by the optical sensor 20 with the reference voltage value previously stored in the controller 40. Therefore, the light unit can maintain the light emission quality relatively even when the surrounding environment such as time and temperature changes.

However, since the luminance of the plurality of light emitting elements 12 is generally decreased as time passes when the same driving current is applied, the self-correction function as described above is driven to be applied to the plurality of light emitting elements 12. Most of this is done by increasing the magnitude of the current CC.

Therefore, when the self-correction function is maintained for the light unit according to the embodiment, in the long term, the magnitude of the driving current CC applied to the plurality of light emitting elements 12 becomes excessively large, so that the plurality of light emission There may be a risk of damage to the device 12 or damage to other components of the light unit according to the embodiment.

Accordingly, the light unit according to the embodiment may further include the warning signal generator 50, and may have a warning function of generating the warning signal ES when the magnitude of the driving current CC is excessively large. have.

The warning signal ES is a current deviation signal CDS comparing the magnitude of the driving current CC currently flowing through the plurality of light emitting elements 12 with the magnitude of the reference driving current stored in the controller 40 in advance. The occurrence thereof may be determined according to the size of.

That is, when the current deviation signal CDS has a predetermined value or more, the warning signal generator 50 generates the warning signal ES. When the current deviation signal CDS is less than the predetermined value, the warning signal ES is generated. Will not occur.

Hereinafter, with reference to each component constituting the light unit according to the embodiment will be described in detail.

The plurality of light emitting elements 12 and the optical sensor 20 may be installed on the substrate 15. In addition, the driver 30, the controller 40, and the warning signal generator 50 may also be installed on the substrate 15, but may be separately formed on other support members, but the present invention is not limited thereto.

The substrate 15 may be formed by printing a circuit pattern on an insulator. For example, a printed circuit board (PCB), a metal core PCB (Metal Core PCB), or a flexible PCB (Flexible PCB) may be formed. It can be either.

The circuit patterns of the substrate 15 are electrically connected to the plurality of light emitting elements 12 and the optical sensor 20 to supply power to the plurality of light emitting elements 12 and the optical sensor 20. I can drive it.

Each of the plurality of light emitting elements 12 may include at least one light emitting diode (LED). The light emitting diode (LED) may be, for example, at least one of a colored light emitting diode emitting red, green, and blue colored light, a white light emitting diode emitting white light, or an ultraviolet (Ultra Violet) light emitting diode emitting ultraviolet light. It may include, but is not limited to this.

The plurality of light emitting devices 12 may be driven by adjusting the brightness and the color sense according to the magnitude of the current applied from the driver 30.

On the other hand, when the plurality of light emitting elements 12 includes the light emitting diodes (LEDs), the brightness and the color of the plurality of light emitting elements 12 may change according to time and temperature.

Furthermore, when the plurality of light emitting devices 12 includes various types of light emitting diodes (LEDs), variations in luminance and color may occur between the light emitting devices 12 according to the types of light emitting diodes (LEDs) included therein. Can be.

Therefore, the light unit according to the embodiment may include the optical sensor 20 and the controller 40, thereby minimizing changes in luminance and color due to time and temperature.

The optical sensor 20 may be installed on the substrate 15. The optical sensor 20 may be a semiconductor light receiving device, and may include, for example, a photo diode, but is not limited thereto.

The optical sensor 20 may detect light emitted from the plurality of light emitting elements 12 and external light of the surroundings, and convert the light into the voltage value SS. In addition, the optical sensor 20 may provide the voltage value SS to the controller 40.

The optical sensor 20 may detect light at predetermined cycle intervals, or detect light when the light unit is turned on or off, but is not limited thereto.

That is, since the luminance and color of the plurality of light emitting elements 12 are not suddenly changed, rather than driving the optical sensor 20 continuously, the predetermined interval or power of the light unit is turned on or off. By driving the optical sensor 20 it is possible to reduce the power consumption of the light unit.

However, the driving method of the optical sensor 20 is not limited thereto. For example, the optical sensor 20 may be continuously driven.

In the case where the optical sensor 20 is driven at the predetermined cycle interval, the cycle is preferably set to 24 hours to 1000 hours without exceeding 1000 hours.

As shown in (Equation 1) below, a value obtained by comparing the initial luminance of the light unit with the luminance after 1000 hours and expressed as a percentage is called luminous flux retention. Therefore, high quality light can be provided to the user.

Luminous flux retention = luminance after 1000 hours / initial luminance * 100 ...... (Equation 1)

Therefore, the light unit according to the embodiment is to set the predetermined period of the optical sensor 20 does not exceed 1000 hours for detecting the light to maintain the luminous flux retention at least 95% or more.

Meanwhile, the predetermined period may be set to increase gradually or decrease gradually. For example, the first period may be increased in units of 100 hours, such as 100 hours, 200 hours, 300 hours, or decreased in units of 100 hours, such as 300 hours, 200 hours, 100 hours, but is not limited thereto.

As such, the reason for setting the predetermined period variably is that the characteristics such as the lifespan of the plurality of light emitting elements 12 are different for each light emitting element, and thus a period optimized for the characteristics of each light emitting element 12 is determined. To set.

The detection result of the luminance and color of light emitted from the light emitting elements 12 sensed by the optical sensor 20 and ambient light of the surroundings is transferred to the voltage value SS by the optical sensor 20. It may be converted and provided to the controller 40.

The controller 40 provides a self-correcting function to the light unit according to the embodiment by controlling the magnitude of the driving current CC flowing through the plurality of light emitting elements 12 using the voltage value SS. In addition, the controller 40 maintains the self-correction function for a long time so that the warning signal generator 50 may generate a warning signal when the driving current CC becomes excessively large, thereby improving reliability of the light unit. Improved.

To this end, the control unit 40 may store the reference voltage value to be compared with respect to the voltage value SS and the reference drive current to be compared with respect to the magnitude of the driving current CC in advance.

Specifically, the control unit 40 controls the magnitude of the driving current CC by comparing the voltage value SS provided from the optical sensor 20 with a reference voltage value stored in advance. May occur. The control signal CS may be provided to the driver 30.

In addition, the controller 40 may generate a current deviation signal CDS comparing the magnitude of the driving current CC with a magnitude of a reference driving current stored in advance, and generate the warning signal using the current deviation signal CDS. The part 50 can be provided.

The warning signal generator 50 may generate a warning signal ES when the current deviation signal CDS provided from the controller 40 has a predetermined value or more.

The reason why the warning signal generator 50 is provided in the light unit according to the exemplary embodiment is that when the driving currents having the same luminance of the plurality of light emitting elements 12 are applied, it is generally decreased as time passes. This is because most of the self-correction functions as described above are made by increasing the magnitude of the driving current CC applied to the plurality of light emitting elements 12.

That is, in the case where the self-correction function is maintained for the light unit according to the embodiment, in the long term, the magnitude of the driving current CC applied to the plurality of light emitting elements 12 becomes excessively large, so that the plurality of light emission units There may be a risk of damage to the device 12 or damage to other components of the light unit according to the embodiment.

Therefore, the light unit according to the embodiment may further include the warning signal generator 50, and may have a warning function for generating the warning signal ES when the magnitude of the driving current CC is excessively large. have.

The occurrence of the warning signal ES may be determined according to the magnitude of the current deviation signal CDS provided from the controller 40.

That is, when the current deviation signal CDS has a predetermined value or more, the warning signal generator 50 generates the warning signal ES. When the current deviation signal CDS is less than the predetermined value, the warning signal ES is generated. Will not occur.

The current deviation signal CDS may represent how much the magnitude of the driving current CC has to the magnitude of the reference driving current as shown in Equation 2 below.

Current deviation signal (CDS) = drive current (CC) / reference drive current * 100 (unit:%)

... (Equation 2)

For example, the warning signal generator 50 may generate the warning signal ES when the current deviation signal CDS has a value of 130%. That is, the warning signal ES may be designed to generate the warning signal ES when the magnitude of the driving current CC becomes 30% larger than the reference driving current.

Hereinafter, a driving method of the light unit according to the embodiment will be described.

2 is a flowchart illustrating a method of driving a light unit according to an embodiment.

Referring to FIG. 2, first, the plurality of light emitting devices 12 emit light by the driving current CC applied from the driving unit 30 (S101).

Next, the light emitted from the plurality of light emitting elements 12 may be detected by the optical sensor 20, and the detected result may be converted into the voltage value SS (S103).

Next, the controller 40 generates the control signal CS by comparing the voltage value SS with a pre-stored reference voltage value, and compares the magnitude of the driving current CC with the magnitude of the reference driving current. The current deviation signal CDS may be generated (S105 and S107).

Next, the driving unit 30 may control the size of the driving current CC to emit light having the desired brightness and color with the plurality of light emitting elements 12 using the control signal CS ( S109).

In addition, the warning signal generator 50 may generate the warning signal ES when the current deviation signal CDS is greater than or equal to a predetermined value.

In addition, the driving method of the light unit according to the above-described embodiment may be repeatedly performed.

Features, structures, effects, and the like described in the above embodiments are included in at least one embodiment of the present invention, and are not necessarily limited to only one embodiment. Furthermore, the features, structures, effects, and the like illustrated in the embodiments may be combined or modified with respect to other embodiments by those skilled in the art to which the embodiments belong. Therefore, it should be understood that the present invention is not limited to these combinations and modifications.

In addition, the above description has been made with reference to the embodiment, which is merely an example, and is not intended to limit the present invention. Those skilled in the art to which the present invention pertains will be illustrated as above without departing from the essential characteristics of the present embodiment. It will be appreciated that various modifications and applications are possible. For example, each component specifically shown in the embodiment can be modified. And differences relating to such modifications and applications will have to be construed as being included in the scope of the invention defined in the appended claims.

12: a plurality of light emitting elements 15: the substrate
20: optical sensor 30: drive unit
40: control unit 50: warning signal generating unit

Claims (11)

A plurality of light emitting elements;
A driving unit applying a driving current to the plurality of light emitting devices;
An optical sensor that detects light emitted from the plurality of light emitting elements and converts the sensing result into a voltage value;
A controller configured to control the magnitude of the drive current by comparing the voltage value with a pre-stored reference voltage value and generate a current deviation signal comparing the magnitude of the drive current with a magnitude of the pre-stored reference drive current; And
And a warning signal generator for generating a warning signal when the current deviation signal provided from the controller has a predetermined value or more. The method of claim 1,
The optical sensor detects light emitted from the plurality of light emitting elements at predetermined periodic intervals. The method of claim 3, wherein
And the predetermined period is from 24 hours to 1000 hours. The method of claim 1,
And the plurality of light emitting elements and the optical sensor are provided on a substrate. The method of claim 1,
The plurality of light emitting devices includes at least one of blue, red, and green light emitting diodes. The method of claim 1,
And the current deviation signal represents a percentage of the magnitude of the drive current relative to the magnitude of the reference drive current. The method of claim 6,
And the warning signal generator generates a warning signal when the current deviation signal is 130% or more. Emitting light by a plurality of light emitting devices by a driving current applied by the driver;
An optical sensor detecting the light and converting the detection result into a voltage value;
A control unit generating a control signal by comparing the voltage value with a previously stored reference voltage value, and generating a current deviation signal by comparing the magnitude of the driving current with the magnitude of a reference driving current;
Controlling the magnitude of the driving current using the control signal in the driver; And
And generating a warning signal when the current deviation signal is equal to or greater than a predetermined value by a warning signal generator. The method of claim 8,
And the optical sensor detects light emitted from the plurality of light emitting elements at predetermined periodic intervals. The method of claim 8,
And the current deviation signal is a value representing the magnitude of the driving current as a percentage with respect to the magnitude of the reference driving current. The method of claim 10,
And the warning signal generator generates a warning signal when the current deviation signal is 130% or more.

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