KR100864905B1 - Driving circuit of lamps - Google Patents

Abstract

A lamp driving circuit is provided to minimize a circuit and to shorten a manufacturing process by using a transformer to implement a current balance of a driving voltage. A lamp driving circuit includes a rectifying unit(110), a PFC(Power Factor Correction) unit(120), a switching unit(130), and a transformer unit(140). The rectifying unit rectifies an input voltage. The PFC unit corrects a power factor of a voltage rectified by the rectifying unit, and converts the rectified voltage into DC voltage. The switching unit converts the DC voltage of the PFC unit into a square wave by switching the DC voltage of the PFC unit. The transformer unit has a transformer having a first input terminal and a second output terminal which are opposite to each other. The transformer receives the square wave voltage outputted from the switching unit, and outputs a plurality of driving voltages for driving the lamps.

Description

Lamp driving circuit {DRIVING CIRCUIT OF LAMPS}

The present invention relates to a lamp driving circuit, and more specifically, a circuit can be miniaturized by driving a plurality of lamps by using a transformer in which an input terminal on a primary side and an output terminal on a secondary side face each other. The present invention relates to a lamp driving circuit capable of shortening a manufacturing process as the lamp driving circuit can be manufactured.

Recently, due to the development of display technology, a monitor, which is a liquid crystal display (LCD), has been increasingly used in a computer or other display device field. When comparing a liquid crystal display and a CRT monitor (Cathode-Ray Tube monitor), the liquid crystal display has the advantage of a slim longitudinal section and reduced flicker.

Such a liquid crystal display device has no self-luminous property and needs to have a back-light module for supplying a light source, and the backlight module has a fluorescent lamp driven at a high pressure.

On the other hand, an inverter is used to drive the fluorescent lamp of the backlight module. The inverter has a high voltage transformer, and the transformer generates a high AC output voltage with a low AC input voltage and supplies it to a lamp constituting the LCD panel. It plays a role.

In this case, since the conventional transformer supplies one lamp driving voltage through one transformer, a plurality of External Electrode Fluorescent Lamps (EEFL) or Cold Cathode Fluorescent Lamps (CCFL) are paralleled. In the case of driving with a large number of transformers are required to drive them.

In addition, as the LCD TV and monitor market matures, the price of backlight module-related components continues to fall as sales prices fall.

Therefore, due to the price pressure of the backlight module-related components, efforts have been made to reduce the number of parts and the unit cost, and as part of this effort, to develop a product capable of driving multiple lamps using a single transformer The movements are active.

With such product development, recently, a transformer has been developed that can output a driving voltage for driving a plurality of lamps respectively using one transformer. At this time, a plurality of driving voltages output from a transformer having multiple outputs are output with different magnitudes.

When the magnitudes of the driving voltages are not the same, there is a problem in that the brightness of the plurality of lamps is changed and the reliability of the backlight module is lowered. Accordingly, a coil for balancing the driving voltage is provided at the output terminal of the transformer, and one coil is provided in each lamp to achieve current balance with neighboring lamps.

However, since the coils for achieving the current balance must be provided for each lamp, when the number of lamps increases, there is a problem in that the size and manufacturing cost of the lamp driving circuit increases, and in order to output a plurality of driving voltages, There was a problem that the size is increased and the insulation is vulnerable.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and the circuit can be miniaturized by driving a plurality of lamps by using a transformer in which the input terminal on the primary side and the output terminal on the secondary side face each other, and on one board As the lamp driving circuit can be manufactured, an object thereof is to provide a lamp driving circuit that can shorten the manufacturing process.

The present invention is to achieve the above object, the lamp driving circuit according to the present invention, the rectifier for rectifying the input voltage; A PFC unit for compensating a power factor of the voltage rectified by the rectifier and converting the rectified voltage into a DC voltage; A switching unit which converts the DC voltage of the PFC unit into a square wave voltage; And a transformer provided on the side of which the input terminal on the primary side and the output terminal on the secondary side face each other, and receive a square wave voltage output from the switching unit, and have a same magnitude to each other and drive a plurality of lamps, respectively. It includes a transformer for outputting a driving voltage.

In this case, the switching unit, characterized in that configured in the half-bridge or full bridge type, the transformer of the transformer, characterized in that the first and second secondary side having one output side and two output terminals, respectively.

The transformer may include a plurality of transformers including one primary side and first and second secondary sides each having two output terminals, and the plurality of transformers may be connected in parallel with each other. It is done.

The transformer may include: a primary winding unit in which a coil of a primary side is wound and having an input terminal and a ground terminal; A first secondary winding unit in which a coil of a first secondary side is wound on one side of the primary winding unit, and having two output terminals; And a second secondary winding unit in which a coil of the second secondary side is wound on the other side of the primary winding unit, and having two output terminals.

In addition, the coil wound on the first secondary winding portion and the second secondary winding portion, characterized in that the number of windings are the same, the coil of the primary side is the winding is started from the input terminal and the winding is terminated at the ground terminal, The input terminal and the ground terminal is characterized in that provided on the same side of the transformer.

In addition, the coils of the first and second secondary side may start winding from one output terminal and finish winding at another output terminal, and two output terminals may be provided on the side facing the input terminal and the ground terminal of the primary side. It is characterized by.

The lamp driving circuit according to the present invention has an effect that the circuit can be miniaturized by using a transformer in which the input terminal on the primary side and the output terminal on the secondary side face each other so that current balancing of the driving voltage is achieved.

In addition, the lamp driving circuit according to the present invention can manufacture a lamp driving circuit for driving a plurality of lamps on one board by using a transformer of the current balance, there is an effect that can shorten the manufacturing process.

Details of the configuration and effects of the lamp driving circuit according to the present invention will be clearly understood by the following detailed description with reference to the drawings showing preferred embodiments of the present invention.

Hereinafter, a lamp driving circuit according to the present invention will be described in more detail with reference to the accompanying drawings.

1 is a block diagram of a lamp driving circuit according to the present invention, Figure 2 is a circuit diagram showing a lamp driving circuit according to the present invention, Figure 3 is a plan view showing a transformer of the lamp driving circuit according to the present invention.

First, as shown in FIG. 1, the lamp driving circuit according to the present invention includes a rectifying unit 110, a PFC unit 120, a switching unit 130, and a transformer unit 140. L2, L3, L4 are driven at the same brightness.

As shown in FIG. 2, the rectifier 110 includes a plurality of diodes, and is full-wave rectified by receiving an input voltage Vin. In this case, the plurality of diodes are configured in a half bridge structure or a full bridge structure.

The PFC unit 120 includes an inductor L, a PWM switching unit M1, and a capacitor C. The PFC unit 120 compensates the power factor of the voltage rectified by the rectifying unit 110 and pre-compensates the rectified voltage. Convert to DC voltage of fixed size.

One end of the inductor L of the PFC unit 120 is connected to the rectifier 110, and the other end thereof is connected to the drain of the PWM switching unit M1 and one end of the capacitor C. In addition, the PWM switching unit M1 has a drain connected to the common node of the inductor L and the capacitor C, the source is grounded, and the PWM control signal P is applied to the gate to control the on / off.

In addition, one end of the capacitor C is connected to the drain of the inductor L and the PWM switching unit M1 and the other end is grounded, thereby being charged by a voltage controlled and transmitted by the PWM switching unit M1. .

The PFC unit 120 having such a configuration converts the voltage applied through the inductor L into a predetermined DC voltage by controlling the PWM switching means M1 by the PWM control signal P.

That is, when the magnitude of the DC voltage is smaller than the magnitude of the predetermined voltage, by increasing the duty width on interval of the PWM control signal (P), by increasing the on interval of the PWM switching means (M1), Increase the magnitude of the DC voltage.

In addition, when the magnitude of the DC voltage is larger than the predetermined voltage, the duty width on period of the PWM control signal P is reduced to decrease the on period of the PWM switching means M1, thereby reducing the magnitude of the DC voltage. Can be reduced.

The switching unit 130 includes a plurality of switching means and a switching controller 131 for controlling the switching means, and converts the DC voltage converted through the PFC unit 120 into a square wave voltage and outputs the square wave voltage. In this case, the switching unit 130 may be of a half bridge type (full bridge type) or a full bridge type (full bridge type), in the present invention is provided with first and second switching means (M2, M3) The half bridge type switching unit 130 will be described.

The first switching unit M2 has a drain connected to a contact point of the inductor L, the PWM switching unit M1 and the capacitor C of the PFC unit 120, and the source of the second switching unit M3. And a first switching signal S1 output from the switching controller 131 to a gate to control the on / off.

In addition, the second switching means M3 has a drain connected to a source of the first switching means M2, a source is grounded, and a second switching signal S2 output from the switching controller 131 to a gate. The on / off control is applied.

In addition, the switching controller 131 controls the first and second switching means M2 and M3 in order to always output a square wave voltage having a constant magnitude in response to the driving voltage output through the transformer 140. The first and second switching signals S1 and S2 are output.

The switching unit 130 having such a configuration includes the first and second switching means M2 and M3 connected to the first and second switching signals S1 and S2 output from the switching controller 131. By cross on / off, the DC voltage output through the PFC unit 120 is output as a square wave voltage.

For example, when the first switching means M2 is turned on by the high level first switching signal S1, the second switching means M3 is a low level second switching. By being turned off by the signal S2, the DC voltage output from the PFC unit 120 is transferred to the transformer unit 140 through the first switching means M2.

In addition, when the second switching means M3 is turned on by the high level second switching signal S2, the first switching means M2 is turned off by the low level first switching signal S1. The DC voltage output from the PFC unit 120 is cut off from supplying the transformer unit 140 to prevent supply of the DC voltage.

By repeating such an operation, the switching unit 130 may convert the DC voltage output from the PFC unit 120 into a square wave voltage and supply it to the transformer unit 140.

In addition, the switching unit 130 may output a DC voltage having a high voltage such as 380 V as a square wave voltage such as 1.8 KVa or 1.1 KVa through the above switching operation, thereby lowering the DC voltage of 380 V. It is not necessary to provide a separate DC to DC converter (DC to DC converter) to make.

Accordingly, the lamp driving circuit according to the present invention can simplify the configuration of the circuit and has an advantage of miniaturization.

The transformer 140 converts the square wave voltage supplied through the switching unit 130 into a plurality of driving voltages to output the plurality of lamps.

At this time, the transformer 140 is composed of one transformer (T1) when outputting four driving voltages to drive four lamps (L1 ~ L4) as shown in Figure 1, a plurality of lamps as shown in FIG. In order to drive (L1 to Ln), it is composed of n / 4 transformers (T1 to T (n / 4)).

First, a case in which one transformer T1 is configured through FIG. 3 will be described.

The transformer T1 has one primary side Np and two first and second secondary sides Ns1 and Ns2. At this time, the primary side Np of the transformer T1 has an input terminal 145a and an output terminal 145b, and the primary coil 142 on the primary winding part 141 provided at the center of the transformer T1. ) Is wound.

In particular, the winding of the primary coil 142 of the transformer T1 starts with the input terminal 145a and the winding ends with the ground terminal 145b. The input terminal 145a and the ground terminal 145b are arranged side by side on one side of the transformer T1.

In addition, the first secondary side Np1 of the transformer T1 is wound around the first secondary winding 143a provided on one side of the primary winding 141, and two output terminals 146a and 146b are wound. It is provided.

In this case, the winding of the first secondary coil 144a wound on the first secondary winding unit 143a starts from one output terminal 146a, and the winding ends at the other output terminal 146b, and the output terminal ( 146a and 146b are formed on the other side of the transformer T1 facing the input terminal 145a and the ground terminal 145b of the primary coil 142a.

As such, the output terminals 146a and 146b of the first secondary coil 144a are not formed on the same side of the input terminal 145a and the ground terminal 145b of the primary coil 142 but on the side facing each other. The reason for this is to ensure insulation by high voltage at the first secondary side Ns1 of the transformer T1.

That is, when one output terminal of the output terminals 146a and 146b of the first secondary coil 144a is formed on the same side as the input terminal 145a, the driving voltage outputted through the first secondary coil 144a to the lamp is again provided. It must be delivered to the side facing the input terminal 145a.

At this time, high voltage flows in the first secondary winding part 143a, and an output terminal on the input terminal 145a side is disconnected by the high voltage, thereby causing a failure, and thus output terminals 146a and 146b for insulation of the transformer T1. ) Are preferably provided on the side facing the input terminal 145a and the ground terminal 145b.

In addition, the second secondary side Ns2 of the transformer T1 is wound around the second secondary winding 143b provided on the side facing the first secondary winding 143a around the primary winding 141. Two output terminals 146c and 146d are provided.

In this case, the second secondary winding 143b also has the same configuration as the first secondary winding 143a, and the output terminals 146c and 146d also face the input terminal 145a and the ground terminal 145b. It can be provided in the insulation.

In particular, the transformer T1 included in the lamp driving circuit according to the present invention may include first and second first and second secondary winding parts 143a and 143b provided at both sides of the primary winding part 141. Since the number of turns of the second secondary coils 144a and 144b is the same, the driving voltages having the same magnitude are output.

Accordingly, when a plurality of driving voltages are output, the first and second secondary coils 144a and 144b of the same number of windings are wound even if a balance portion for outputting and balancing the driving voltages having different magnitudes is not provided separately. By outputting a plurality of driving voltages always having a constant size through the first and second secondary windings 143a and 143b, the size of the circuit can be reduced.

In addition, the transformer T1 of the transformer unit 140 according to the present invention is capable of outputting four driving voltages from one transformer T1, thereby driving one transformer when driving four lamps L1 to L4. By using only T1, all four lamps L1 to L4 can be driven, thereby reducing the volume.

And, as shown in Figure 2, when driving a plurality of lamps (L1 ~ Ln) consisting of four or more, the primary side (Np) of a plurality of transformers (T1 ~ T (n / 4)) having the configuration as described above ) In parallel with each other, it is possible to drive a plurality of lamps (L1 ~ Ln) with the same brightness.

In particular, in order to drive the plurality of lamps (L1 ~ Ln), produced by dividing into an inverter board (inveretr board) having a lamp driving circuit for outputting a plurality of driving voltages, and a balance board (balance board) with a balance As a result, the present invention is configured to output a driving voltage of the same size through only one board provided with a lamp driving circuit, thereby shortening the manufacturing process and manufacturing time. Can be.

On the other hand, as shown in Figure 4 showing a modified example of the lamp driving circuit according to the present invention, when driving the "U" shaped lamp, not a straight lamp, one end of the first lamp (L1) to the transformer (T1) Is connected to the first secondary side (Ns1) of the high pressure terminal (N1), and the other end of the first secondary side (Ns1) to the low pressure terminal (N2).

In addition, one end of the second lamp (L2) is connected to the high pressure terminal (N3) of the second secondary side (Ns2) of the transformer (T1), and the other end to the low pressure terminal (N4) of the second secondary side (Ns2). Connect.

Accordingly, the two "U" shaped lamps can be driven through one transformer T1, and thus, fewer transformers are required than when driving one "U" shaped lamp in the conventional transformer. , Can reduce the volume of the circuit.

Preferred embodiments of the present invention described above are disclosed for the purpose of illustration, and various substitutions, modifications, and changes within the scope without departing from the spirit of the present invention for those skilled in the art to which the present invention pertains. It will be possible, but such substitutions, changes and the like should be regarded as belonging to the following claims.

1 is a block diagram of a lamp driving circuit according to the present invention;

2 is a circuit diagram showing a lamp driving circuit according to the present invention.

3 is a plan view illustrating a transformer of a lamp driving circuit according to the present invention;

4 is a circuit diagram showing a modification of the lamp driving circuit according to the present invention.

<Description of Symbols for Major Parts of Drawings>

110: rectifier 120: PFC unit

130: switching unit 131: switching control unit

140: transformer 141: primary winding

143a: first secondary winding 143b: second secondary winding

Claims (9)

A rectifier for rectifying the input voltage; A PFC unit for compensating a power factor of the voltage rectified by the rectifier and converting the rectified voltage into a DC voltage; A switching unit which converts the DC voltage of the PFC unit into a square wave voltage; And It includes a transformer provided on the side that the input terminal of the primary side and the output terminal of the secondary side facing each other, a plurality of driving for driving a plurality of lamps each having the same size and receiving the square wave voltage output from the switching unit It includes; a transformer for outputting a voltage, The transformer of the transformer part, 1. A lamp driving circuit comprising one primary side and first and second secondary sides each having two output terminals. The method of claim 1, The switching unit is a lamp driving circuit, characterized in that configured in the half bridge or full bridge type. delete A rectifier for rectifying the input voltage; A PFC unit for compensating a power factor of the voltage rectified by the rectifier and converting the rectified voltage into a DC voltage; A switching unit which converts the DC voltage of the PFC unit into a square wave voltage; And It includes a transformer provided on the side that the input terminal of the primary side and the output terminal of the secondary side facing each other, a plurality of driving for driving a plurality of lamps each having the same size and receiving the square wave voltage output from the switching unit It includes; a transformer for outputting a voltage, The transformer unit, A lamp driving circuit comprising a plurality of transformers comprising one primary side and first and second secondary sides each having two output terminals. The method of claim 4, wherein The plurality of transformers are lamp driving circuit, characterized in that the primary side is connected in parallel with each other. The method according to claim 1 or 4, The transformer, A primary coil wound on the primary side and having an input terminal and a ground terminal; A first secondary winding unit in which a coil of a first secondary side is wound on one side of the primary winding unit, and having two output terminals; And A second secondary winding unit having a second secondary coil wound on the other side of the primary winding unit and having two output terminals; Lamp driving circuit comprising a. The method of claim 6, The coil wound around the first secondary winding portion and the second secondary winding portion, the lamp driving circuit, characterized in that the same number of turns. The method of claim 6, The primary coil has a winding starting from the input terminal and the winding is terminated at the ground terminal, the input terminal and the ground terminal lamp driving circuit, characterized in that provided on the same side of the transformer. The method of claim 6, The coils of the first and second secondary side may start winding from one output terminal and finish winding at another output terminal, and the two output terminals may be provided on the side facing the input terminal and the ground terminal of the primary side. Lamp driving circuit characterized in that.

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