KR20100029597A - Device for driving lamp - Google Patents

Device for driving lamp Download PDF

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Publication number
KR20100029597A
KR20100029597A KR1020080088432A KR20080088432A KR20100029597A KR 20100029597 A KR20100029597 A KR 20100029597A KR 1020080088432 A KR1020080088432 A KR 1020080088432A KR 20080088432 A KR20080088432 A KR 20080088432A KR 20100029597 A KR20100029597 A KR 20100029597A
Authority
KR
South Korea
Prior art keywords
temperature
output current
transformer
thermistor
control unit
Prior art date
Application number
KR1020080088432A
Other languages
Korean (ko)
Inventor
장민석
Original Assignee
엘지이노텍 주식회사
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 엘지이노텍 주식회사 filed Critical 엘지이노텍 주식회사
Priority to KR1020080088432A priority Critical patent/KR20100029597A/en
Publication of KR20100029597A publication Critical patent/KR20100029597A/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V23/00—Arrangement of electric circuit elements in or on lighting devices
    • F21V23/02—Arrangement of electric circuit elements in or on lighting devices the elements being transformers, impedances or power supply units, e.g. a transformer with a rectifier
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/36—Controlling
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/1336—Illuminating devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B1/00—Details of electric heating devices
    • H05B1/02—Automatic switching arrangements specially adapted to apparatus ; Control of heating devices
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
    • H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
    • H05B41/14—Circuit arrangements
    • H05B41/46—Circuits providing for substitution in case of failure of the lamp

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Circuit Arrangements For Discharge Lamps (AREA)

Abstract

PURPOSE: A device for driving a lamp is provided to improve reliability of a product by installing a temperature controller reducing an output current if the temperature of a transformer rises. CONSTITUTION: A transformer(100) receives an input current and supplies the output current. An output current controller(200) controls the output current. A temperature controller(500) reduces the output current when the temperature of transformer is increased. The temperature controller comprises a comparison unit(520) and a temperature sensing part(510) sensing the temperature of the transformer. The comparison unit compares the temperature of detected transformer with a reference temperature. The temperature sensing part comprises a thermistor.

Description

Lamp drive unit {DEVICE FOR DRIVING LAMP}

The present invention relates to a lamp driving device.

In general, since the liquid crystal display does not emit light by itself, a separate light source called a backlight is required, and such a backlight includes a light emitting diode (LED) and a cold cathode fluorescent lamp (CCFL). An external electrode fluorescent lamp (EEFL) is used, and an inverter is required to drive a cold cathode fluorescent lamp or an external electrode fluorescent lamp.

On the other hand, the inverter uses a fluorescent lamp as a load, but due to the characteristics of the lamp is turned on when a high-voltage AC signal is applied, it is necessary to use the FET and Transformer to implement such a signal. The problem is the thermal problem that occurs during switching. In the limited part of the mechanical height and PCB size, the temperature rise of the components reduces the stability of the overall inverter module. If the protection circuit is not configured, the components can be damaged. There was a problem.

The present invention is to provide a lamp driving device that can prevent the parts of the circuit breakage or malfunction due to the rise in temperature.

Lamp driving apparatus according to an embodiment of the present invention includes a transformer for providing an output current by receiving an input current, an output current controller for controlling the output current, and a temperature controller for controlling the output current to decrease when the temperature of the transformer rises do.

The lamp driving apparatus of the present invention has the effect of preventing component damage or malfunction of the circuit caused by the temperature rise.

In addition, the lamp driving apparatus of the present invention has the effect of improving the reliability of the product by preventing malfunction even at high temperatures.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. Specific details of other embodiments are included in the detailed description and the drawings. Advantages and features of the present invention and methods for achieving them will be apparent with reference to the embodiments described below in detail with the accompanying drawings. Like reference numerals refer to like elements throughout.

1 is for explaining a lamp driving apparatus according to an embodiment of the present invention, Figure 2 is for explaining a thermistor that changes according to the temperature of the temperature control unit of the lamp driving apparatus according to an embodiment of the present invention, 3 is for explaining the operation of the lamp driving apparatus according to the temperature according to an embodiment of the present invention.

Lamp driving apparatus according to an embodiment of the present invention as shown in Figure 1, the transformer 100, the output current control unit 200, the current control unit 300, the external electrode fluorescent lamp 400 and the temperature control unit 500 It may be configured to include).

First, the transformer 100 may receive an input current and provide an output current. The first secondary winding of the transformer 100 is connected to the first capacitor C1 and the second capacitor C2. The first capacitor C1 and the second capacitor C2 are disposed in parallel with each other, are arranged in series with the first secondary winding of the transformer 100, and provide a DC of the first secondary side of the transformer 100. It can either block or resonate.

In addition, the second secondary winding of the transformer 100 is connected to a third capacitor C3 capable of resonating the second secondary side of the transformer 100. In this case, the second secondary winding of the transformer 100 may be disposed in parallel with the third capacitor C3. The second secondary winding of the transformer 100 is connected to the external electrode fluorescent lamp 400.

The output current controller 200 is connected to the second secondary winding of the transformer 100 and controls the output current supplied through the transformer 100. The output current controller 200 may be configured of a first resistor R1 and a second resistor R3. The first register R1 and the second register R3 may be arranged in parallel.

The current controller 300 is connected to a main integrated circuit (IC) terminal that receives an output current. The current controller 300 may set the output of the main integrated circuit to be high when the output current is smaller than the set reference current, and to set the output of the main integrated circuit to be low when the output current is larger than the set reference current.

External Electrode Fluorescent Lamp (400, EEFL), unlike ordinary lamps, has an electrode outside the lamp and emits light by inducing plasma discharge in the lamp by an electric field applied to the electrode. As it does not occur, it has little heat dissipation and has a long lifespan. Accordingly, the external electrode fluorescent lamp 400 can drive several lamps in parallel by using a low voltage. Although the external electrode fluorescent lamp is illustrated in the present invention, a cold cathode fluorescent lamp (CCFL) may be used.

The temperature controller 500 controls the output current to decrease as the temperature of the transformer rises. The temperature controller 500 controls the temperature of the output current according to a signal supplied through the temperature detector 510 for detecting the temperature of the transformer, the comparator 520 for comparing the sensed temperature, and the comparator 520. It may be configured to include an output current controller 530.

First, the temperature detector 510 may include a plurality of resistors R4 to R7 and capacitors C5 to C6. At least one of the plurality of registers R4 to R7 may include a thermistor R4. The temperature sensing unit 510 senses the temperature of the transformer and the temperature of the lamp driving device and the ambient temperature. That is, one end of the temperature sensing unit 510 senses the temperature of the transformer, and the other end detects a reference temperature based on the temperature of the lamp driving device and the ambient temperature. Accordingly, one end of the temperature sensing unit 510 for sensing the temperature of the transformer is configured to include a temperature sensitive thermistor (R4). This thermistor will be described later.

The comparator 520 includes a first stage that is a positive end, a second stage that is a negative end, and a third stage that is an output end. The comparator 520 outputs a signal through the third stage by comparing the voltage values received through the first and second stages. Here, the first end of the comparator 520 and one end of the temperature sensor 510 are connected, and the second end of the comparator 520 and the other end of the temperature sensor 510 are connected.

The temperature output current controller 530 controls the output current according to the signal output through the comparator. The temperature output current controller 530 is disposed between the comparator 520 and the output current controller 200, and may include a third resistor R3. Accordingly, one end of the third register R3 is connected to the third end of the comparator 520, and the other end is connected to one end of the first register R1 and one end of the second register R2. Therefore, the first register R1, the second register R2 and the third register R3 are arranged in parallel with each other.

Figure 2 shows that the thermistor resistance value of the thermistor of the temperature control unit changes according to the change in temperature.

Here, thermistor may be characterized by a negative resistance temperature coefficient, in which, unlike a general metal, the resistance decreases with increasing temperature. This is called a negative temperature coefficient thermistor (NTC). In addition, these thermistors (thermistors) are small and can be used as a sensor for temperature control because a sudden resistance change occurs even with a small temperature change. That is, a thermistor is a device whose resistance value varies with temperature. It can be seen from the table shown in FIG. 2 that the resistance value of the thermistor varies from 224.33 0.8 to 0.85 ㏀ according to the temperature, and the thermistor has a small resistance value as the temperature rises from low temperature to high temperature. You can see the loss. The operation of the temperature controller using the characteristics of the thermistor will be described with reference to FIG. 3.

First, one end of the temperature sensing unit 510 senses the temperature of the transformer, and the other end detects a reference temperature based on the temperature of the lamp driving device and the ambient temperature. The temperature sensed at one end and the other end of the temperature detector 510 is supplied through the first and second stages of the comparator 520.

In this case, the change in the temperature sensed at one end of the temperature detector 510 may be known using the temperature sensed at the other end of the temperature detector 510 as a reference temperature.

In other words, when the temperature sensed at one end of the temperature detector 510 is greater than the temperature sensed at the other end of the temperature detector 510, the first stage of the comparator 520 is larger than the second stage. As such, when the first end of the comparator 520 is larger than the second end, the third end of the comparator 520 is in a state of not supplying an output signal. That is, the third end of the comparator 520 is in a floating state in which no voltage is supplied.

As such, the third end of the comparator 520 is in a floating state, and thus the third end of the comparator 520 and the temperature output current controller 530 are not connected to each other. That is, one end of the third resistor R3 and the third end of the comparison unit 520 are not connected, and only the other end of the third resistor R3 and the output current controller 200 are connected. Accordingly, one end of the third register R3 is not connected, and thus the third register R3 cannot function as a register. Therefore, the output current is supplied to the current controller 300 through the first resistor R1 and the second resistor R2 arranged in parallel.

In addition, when the temperature sensed at one end of the temperature detector 510 is smaller than the temperature sensed at the other end of the temperature detector 510, the second stage of the comparator 520 is larger than the first stage. As described above, when the second end of the comparator 520 is larger than the first end, the third end of the comparator 520 is in a reference voltage GND state.

As such, when the third end of the comparator 520 is in the reference voltage GND state, one end of the third resistor R3 is connected to the reference voltage GND, and the other end of the third resistor R3 and the output current. The control unit 200 is connected. Accordingly, the output current is supplied to the current controller 300 through the first resistor R1, the second resistor R2, and the third resistor R3 arranged in parallel.

As described above, when the temperature is high, the output current is controlled by the first resistor R1 and the second resistor R2 arranged in parallel, and when the temperature is normal, the first resistor R1 in which the output current is arranged in parallel, The resistance value of the output current can be varied by being controlled by the second resistor R2 and the third resistor R3.

Therefore, the resistance value of the output current controlled by the two resistors R at a high temperature is relatively larger than the resistance value of the output current controlled by the three R resistors at room temperature. As the resistance value of the output current increases, the voltage value fed back to the main integrated circuit increases. Accordingly, the main integrated circuit sets the output current low, and when the output current is low, the temperature of the transformer can be lowered.

While the invention has been described and illustrated in connection with a preferred embodiment for illustrating the principles of the invention, the invention is not limited to the configuration and operation as such is shown and described.

Rather, those skilled in the art will appreciate that many modifications and variations of the present invention are possible without departing from the spirit and scope of the appended claims.

Accordingly, all such suitable changes and modifications and equivalents should be considered to be within the scope of the present invention.

1 is for explaining a lamp driving apparatus according to an embodiment of the present invention.

2 is for explaining a thermistor that changes according to the temperature of the temperature control unit of the lamp driving apparatus according to an embodiment of the present invention.

3 is for explaining the operation of the lamp driving apparatus according to the temperature according to an embodiment of the present invention.

<Description of Signs of Major Parts of Drawings>

100: transformer 200: output current control unit

300: current control unit 400: external electrode fluorescent lamp

500: temperature control unit 510: temperature detection unit

520: comparison unit 530: temperature output current control unit

Claims (6)

A transformer configured to receive an input current and provide an output current; An output current controller for controlling the output current; And A temperature control unit controlling the output current to decrease as the temperature of the transformer increases; Lamp driving device comprising a. According to claim 1, The temperature control unit A temperature sensing unit sensing a temperature of the transformer; A comparison unit comparing the sensed temperature of the transformer with a reference temperature; And A temperature output current control unit controlling the output current according to the signal supplied through the comparison unit; Lamp driving apparatus comprising a. The method of claim 2, The lamp driving device, characterized in that the temperature sensor comprises a thermistor (Thermistor). The method according to claim 2 or 3, If the temperature detected by the temperature detector is higher than the reference temperature, And the temperature output current control unit and the comparison unit are in a floating state. The method of claim 3, wherein The comparator includes a first end that is a positive end and a second end that is a negative end, And the thermistor is connected to the first end. The method of claim 2, And the output current controller and the temperature output current controller are connected to each other.
KR1020080088432A 2008-09-08 2008-09-08 Device for driving lamp KR20100029597A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
KR1020080088432A KR20100029597A (en) 2008-09-08 2008-09-08 Device for driving lamp

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
KR1020080088432A KR20100029597A (en) 2008-09-08 2008-09-08 Device for driving lamp

Publications (1)

Publication Number Publication Date
KR20100029597A true KR20100029597A (en) 2010-03-17

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Family Applications (1)

Application Number Title Priority Date Filing Date
KR1020080088432A KR20100029597A (en) 2008-09-08 2008-09-08 Device for driving lamp

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