KR100992252B1 - Lamp driving power supply having current balancing fuction - Google Patents

Abstract

The present invention relates to a lamp driving power supply having a current balancing function that maintains the balance of the current supplied to the lamp by employing two switches connected in series to one end of the lamp, the input power is switched in advance An inverter unit for supplying a lamp driving AC power having a set voltage level to the lamp, and switching the lamp driving AC power from the lamp to control the current of the lamp driving AC power to maintain the current balance of the lamp It is to provide a lamp driving power supply having a current balancing function comprising a current balance.

Liquid Crystal Display (LCD), Current Balancing, Digital Control

Description

LAMP DRIVING POWER SUPPLY HAVING CURRENT BALANCING FUCTION}

The present invention relates to a power supply device for driving a lamp, and more particularly, a lamp driving power supply having a current balancing function for maintaining a balance of current supplied to a lamp by employing two switches connected in series to one end of the lamp. It relates to a supply device.

Recently, the liquid crystal display (LCD) is a representative flat panel display in the global display market, and is particularly a display device attracting attention in the monitor, mobile phone and digital TV market.

Since the liquid crystal display is not a display using a light emitting device, a backlight unit (BLU) serving as a light source is required. Light sources of current backlight units include a cold cathode fluorescent lamp (CCFL), a flat fluorescent lamp (FFL), and a light emitting diode (LED).

Meanwhile, in the case of a display device, a user's demand for a wider screen is increasing, and as the screen is wider, the voltage and power supplied to the lamp increase as the number of lamps and the length of the lamps used in the backlight unit increase. .

In the case of a cold cathode fluorescent lamp (CCFL), which is mainly used for a backlight unit, as the length increases, the light emission start voltage for emitting the lamp increases, so as the screen becomes larger, a power supply for stably emitting and driving the lamp is required. . In addition, since the impedance value of the lamp in the pre-lighting state and the lighting state are significantly different, parallel driving is difficult in the general method.

That is, in applying the voltage to the lamp, a high voltage is applied in the pre-lighting state, but when the light is turned on, the voltage applied to the lamp rapidly decreases. As a result, when a lamp is driven by a simple parallel connection, when one lamp is turned on, the applied voltage is lowered, almost all currents flow to the lit lamp, and the rest of the lamps are not turned on. Current balancing is needed to eliminate this problem.

Representative examples of the current balance include a method using a transformer and a method using a ballast capacitor.

The methods using the transformer have been developed circuits named Jin Balance, ZAUlas (Zip As Uni-Lamp System), etc.Current Balance Transformer (Current Balance) is used to light several lamps simultaneously with one inverter. It is a method to light a plurality of lamps at the same time by equalizing the current flowing through each lamp by inserting a transformer) to reduce the difference between lamp currents.

The above-described schemes have a large current balancing circuit and have a trade-off relationship between the initial lighting condition and the tube current deviation, making it difficult to satisfy both conditions.

The method using the ballast capacitor serves to ignore the gap between the lamps because the impedance of the capacitor connected in series to the lamp is equal to or higher than the impedance of the lamp. This ensures the voltage of the other lamps connected in parallel, thus enabling parallel lighting. However, for this purpose, the voltage applied to the capacitor is greater than the driving voltage of the lamp, so that the internal voltage of the capacitor is a considerable high voltage and its price is also expensive. In addition, there is a problem of shortening the life due to the heat generated in the high-voltage capacitor, there is a problem in that the driving circuit to drive the circuit with a large voltage in order to compensate for the voltage applied to the capacitor and to turn on the lamp.

Therefore, there is a demand for a new current balancing circuit that can replace the existing current balancing circuit having the above-described problem.

In order to solve the above problems, an object of the present invention is to provide a lamp driving power supply having a current balancing function to maintain the balance of the current supplied to the lamp by employing two switches connected in series to one end of the lamp To provide.

In order to achieve the above object, one technical aspect of the present invention is an inverter unit for supplying a lamp driving AC power having a predetermined voltage level by switching the input power to the lamp, and for driving the lamp from the lamp It is to provide a lamp driving power supply having a current balancing function characterized in that it comprises a current balancing unit for switching the AC power to control the current of the lamp driving AC power to maintain the current balance of the lamp.

According to one technical aspect of the present invention, the current balance unit is electrically connected to one end of the lamp and the switch group for conducting or inhibiting transmission of AC power for driving a lamp from the lamp, and conduction of the switch group. And a balance switching controller providing a switching control signal for controlling the suppression operation.

According to one technical aspect of the present invention, the switch group may be electrically connected to one end of the lamp, and according to the switching control signal, a first period of half of one cycle of AC power for driving the lamp according to the switching control signal. And a second switch electrically connected in series to the first switch to suppress the transfer of the current of the other half cycle of one cycle of the lamp driving AC power from the first switch according to the switching control signal. have.

According to one technical aspect of the present invention, the switch group includes a first parasitic diode connected in parallel with the first switch, the first parasitic diode having a cathode connected to one end of the lamp and an anode connected to the second switch; A first parasitic capacitor connected in parallel to the parasitic diode and the first switch, a second parasitic diode connected in parallel with the second switch, a second parasitic diode having a cathode connected to one end of the inverter unit and an anode connected to the first switch, The display device may further include a second parasitic capacitor connected in parallel to the second parasitic diode and the second switch.

According to one technical aspect of the present invention, the balance switching controller includes a current sensing unit for detecting a current of an AC power source for driving a lamp from the lamp, and the conduction and suppression operation of the switch group according to the detected current value. A control unit for providing a control signal for controlling the control unit, and amplifying the current and voltage levels of the control signal from the control unit to current and voltage levels that can be driven by each switch in the switch group to provide the switching control signal. It may include a drive unit.

According to one technical aspect of the present invention, the inverter unit may be a parallel resonance half bridge inverter.

Another technical aspect of the present invention is an inverter unit for supplying a lamp driving AC power having a predetermined voltage level by switching an input power supply to the lamp, and connected in series between the inverter unit and the lamp, the inverter And a current balancer for switching the lamp driving AC power from the lamp to control the current of the lamp driving AC power to maintain the current balance introduced into the lamp. To provide a device.

According to another technical aspect of the present invention, the current balance unit is electrically connected to the output terminal of the inverter unit switch group for transmitting or suppressing the AC power for driving the lamp from the inverter unit and the switch group, A balance switching controller may be provided that provides a switching control signal to control the transfer and suppression operation of the.

According to another technical aspect of the present invention, the switch group is electrically connected to the output terminal of the inverter unit and suppresses the transmission of the current of the half cycle of one cycle of the AC power for driving the lamp according to the switching control signal. A second switch electrically connected in series between the first switch and the lamp to suppress transmission of the current of the other half of one cycle of the AC power for driving the lamp from the first switch according to the switching control signal; It may include.

According to another technical aspect of the present invention, the switch group may include a first parasitic diode connected in parallel with the first switch, the first parasitic diode having a cathode connected to an output terminal of the inverter unit and an anode connected to the second switch; A first parasitic capacitor connected in parallel to a first parasitic diode and a first switch, a second parasitic diode having a cathode connected in parallel with the second switch, a cathode connected to the lamp, and an anode connected to the first switch, and the second The parasitic diode may further include a second parasitic capacitor connected in parallel to the second switch.

According to another technical aspect of the present invention, the balance switching controller includes a current sensing unit for detecting a current of a lamp driving AC power delivered to the lamp, the transfer of the switch group according to the detected current value and A control unit providing a control signal for controlling the suppression operation, and amplifying the current and voltage levels of the control signal from the control unit to a current and voltage level that each switch in the switch group can drive to convert the switching control signal. It may include a drive unit to provide.

According to the present invention, the current supplied to the lamp is adopted by employing two switches connected in series to one end of each lamp to control the conduction and suppression of the transfer of current from the lamp, compared to the current balancing method using only a transformer or capacitor. By maintaining the equilibrium, there is an effect of maintaining the equilibrium of the plurality of lamps while suppressing an increase in circuit area and manufacturing cost.

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

BRIEF DESCRIPTION OF THE DRAWINGS It is a block diagram which shows one Embodiment of the power supply apparatus of this invention.

Referring to FIG. 1, the power supply device 100 of the present invention includes an inverter unit 110, a current balance unit 120, and a lamp group 130.

The inverter unit 110 supplies an AC power for driving a lamp having a preset voltage level by switching the input power Vin.

The inverter unit 110 includes a half bridge type switch having capacitors C1 and C2 and at least two switches S1 and S2 connected in parallel to an input power source Vin, and an inductor L1 at a primary side. And a parallel resonant type transformer having a magnetizing inductor Lm.

Although not shown in the drawings, the switch of the inverter unit 110 may be configured as a full bridge type switch or a push-pull type switch.

The AC power for driving the lamp from the inverter unit 110 is transmitted to the lamp group 130.

The lamp group 130 may include at least one lamp, and may include first to Nth lamps 131 to 13N in consideration of a screen area of a display device employing the power supply device of the present invention.

The first to Nth lamps 131 to 13N of the lamp group 130 may receive light from the AC driving power source from the inverter unit 110 to emit light. Impedances of the first to Nth lamps 131 to 13N of the lamp group 130 may not be constant, and thus a current balancing circuit is employed because a variation in the current flowing therein occurs.

The current balancer 120 detects a current from the first to Nth lamps 131 to 13N of the lamp group 130, and controls the transfer or interruption of the current delivered to the ground according to the detected current value. The current balance of the lamp driving AC power flowing into the first to N-th lamps 131 to 13N of the group 130 is controlled.

The current balance unit 120 may include a switch group 121 and a balance switching controller 122, and the switch group 121 may include first to Nth switch groups 121-1 to 121 -N. The first to Nth switch groups 121-1 to 121 -N of the switch group 121 correspond to the first to Nth lamps 131 to 13N of the lamp group 130, respectively.

The first to Nth switch groups 121-1 to 121 -N may include first and second switches Sb1 and Sb2 connected in series between one end of the lamp and the ground, respectively. The semiconductor device may further include first and second parasitic diodes Sbd1 and Sbd2 and first and second parasitic capacitors Sbc1 and Sbc2 connected in parallel to Sb1 and Sb2, respectively.

The balance switching controller 122 senses a current through the first through N-th switch groups 121-1 through 121 -N to transfer current through the first through N-th switch groups 121-1 through 121 -N. And control blocking.

Accordingly, the balance switching controller 122 includes a current sensing unit 122a for detecting current through the first to Nth switch groups 121-1 to 121 -N, and a current detected from the current sensing unit 122a. The control unit 122b for controlling the transfer and suppression of current through the first to Nth switch groups 121-1 to 121-N according to the value, and the voltage and current level of the control signal of the control unit 122b. A driving unit 122c for amplifying the switch to drive and transferring the switching control signal to the first and second switches of the first to Nth switch groups 121-1 to 121 -N.

In addition, a plurality of ballast capacitors Cb are disposed between the respective lamps 131 to 13N and the output terminal of the inverter unit 110 for initial lighting of the plurality of lamps 131 to 13N of the lamp group 130. Each may be electrically connected.

2 is a configuration diagram showing another embodiment of the power supply device of the present invention.

Referring to FIG. 2, the power supply 200 of the present invention is electrically connected to the lamp groups 130 and 230 and the current balancer 120 and 220 in comparison with the power supply 100 of the present invention shown in FIG. 1. This is different.

That is, the current balance unit 220 receives the AC power for driving the lamp from the inverter unit 210 and controls the transfer or suppression to each lamp of the lamp group 230 to maintain the current balance of each lamp.

The configuration and operation of the switch group 221 and the balance switching controller 222 of the current balance unit 220 are the same as the switch group 121 and the balance switching controller 122 shown in FIG. 1 except for the electrical connection relationship. Therefore, detailed description will be omitted.

Referring to Figure 1 will be described with respect to the principle of the current balance of the present invention. The principle of current balancing of the power supply 200 shown in FIG. 2 is also the same as that of the power supply 100 shown in FIG. 1, so that the details of the principle of current balancing of the power supply 200 shown in FIG. The description is omitted.

The AC power for driving the lamp from the inverter unit 110 shown in FIG. 1 is transmitted to the first to Nth lamps 131 to 13N of the lamp group 130, and the first to Nth of the lamp group 130. The AC power for driving the lamp through the lamps 131 to 13N is transmitted or suppressed by the switching group 121 of the current balance unit 120.

That is, when the switching control signal SSb from the balance switching controller 122 is a switching on signal, the first and second switches of the first to Nth switch groups 121-1 to 121 -N of the switch group 121 are included. (Sb1, Sb2) is turned on (turn on) so that the AC power for driving the lamp from the inverter unit 110 of the first to N-th lamp (131 ~ 13N) of the lamp group 130 and the switch group 121 Paths are formed through the first to Nth switch groups 121-1 to 121 -N to ground, and are transmitted to the first to Nth lamps 131 to 13N of the lamp group 130, and each lamp Emits light.

At this time, the current sensing unit 122a detects the current of the lamp driving AC power, and may separately detect the current passing through each lamp. The detected current is transmitted to the control unit 122b, and the control unit 122b can individually control the current balance of each lamp, and the switching control signal SSb from the drive unit 122c is applied to each switch group. It can be delivered individually to control the current balance of each lamp individually.

On the other hand, if the switching control signal SSb from the balance switching controller 122 is a switching off signal, the first and second of the first to Nth switch groups 121-1 to 121 -N of the switch group 121 may be used. The switches Sb1 and Sb2 are turned off so that the transfer path of the AC power for driving the lamp is not formed. At this time, the first and second switches Sb1 and Sb2 are turned off, but are connected to the first and second parasitic diodes Sbd1 and Sbd2 and the first and second parasitic capacitors Sbc1 and Sbc2 connected in parallel to each switch. The path of the lamp driving AC power may be formed.

However, the first and second parasitic diodes Sbd1 and Sbd2 are connected in reverse with each other in series to block the transmission paths of the positive and negative half periods of the AC power supply for driving the lamps. The two parasitic capacitors Sbc1 and Sbc2 are connected in series to each other to provide an impedance that suppresses the transfer of the AC power for driving the lamp. Accordingly, the transfer is suppressed in both the positive (+) half cycle and the negative (-) half cycle which constitute one cycle of the lamp driving AC power, thereby easily suppressing the current delivered to each lamp.

Accordingly, the current balance unit 120 can easily control the current flowing through each lamp individually, thereby maintaining the current balance of the lamp.

The first and second switches Sb1 and Sb2 may be formed of a transistor, a metal oxide semiconductor field-effect transistor (MOSFET), and the like. Of course, it can be configured in any switch form that can control the.

3 is a graph of the current characteristics of the power supply of the present invention.

1 and 3, in the power supply device 100 of the present invention, the first and second switches Sb1 and Sb2 of the switch group 121 are driven by a switching control signal SSb. It is possible to block all of the cycles so that the current level can be clearly seen at the time of switching on and off of the switching control signal SSb, thereby easily maintaining the balance of the current flowing through each lamp.

The present invention described above is not limited to the above-described embodiment and the accompanying drawings, but is defined by the claims below, and the configuration of the present invention may be modified in various ways without departing from the technical spirit of the present invention. It will be apparent to those skilled in the art that the present invention may be changed and modified.

BRIEF DESCRIPTION OF THE DRAWINGS The block diagram which shows one Embodiment of the power supply apparatus of this invention.

2 is a configuration diagram showing another embodiment of the power supply apparatus of the present invention.

Figure 3 is a current characteristic graph of the power supply of the present invention.

<Detailed Description of Major Symbols in Drawing>

100,200 ... Power supply unit 110,210 ... Inverter section

120,220 ... current balance 121,221 ... switch group

122,222 ... balance switching controller 122a, 222a ... current sensing unit

122b, 222b ... control unit 122c, 222c ... drive unit

130,230 ... lamp group

131-13N, 231-23N ... 1st-Nth lamp

121-1 to 121-N, 221-1 to 221-N ... 1st to Nth switch group

Claims (12)

delete delete An inverter unit for switching the input power to supply a lamp driving AC power having a predetermined voltage level to the lamp; And And a current balancer for switching the lamp driving AC power from the lamp to control the current of the lamp driving AC power to maintain the current balance of the lamp. The current balance unit A switch group electrically connected to one end of the lamp to conduct or inhibit transmission of an AC power source for driving a lamp from the lamp; And A balance switching controller providing a switching control signal for controlling conduction and suppression operations of the switch group, The switch group A first switch electrically connected to one end of the lamp to suppress transmission of a current in one half of one cycle of the lamp driving AC power according to the switching control signal; And A second switch electrically connected to the first switch to suppress transmission of the current of the other half cycle of one cycle of the lamp driving AC power from the first switch according to the switching control signal; Lamp driving power supply having a current balancing function comprising a. The method of claim 3, wherein the switch group A first parasitic diode connected in parallel with the first switch and having a cathode connected to one end of the lamp and an anode connected to the second switch; A first parasitic capacitor connected in parallel to the first parasitic diode and the first switch; A second parasitic diode connected in parallel with the second switch, the second parasitic diode having a cathode connected to one end of the interleaver and an anode connected to the first switch; And And a second parasitic capacitor connected in parallel to the second parasitic diode and the second switch. 4. The balance switching controller of claim 3 wherein A current sensing unit for detecting a current of an AC power source for driving a lamp from the lamp; A control unit for providing a control signal for controlling the conduction and suppression operations of the switch group in accordance with the detected current value; And A drive unit which amplifies the current and voltage levels of the control signal from the control unit to a current and voltage level that each switch in the switch group can drive to provide the switching control signal; Lamp driving power supply having a current balancing function comprising a. The method of claim 3, The inverter unit is a power supply device for driving a lamp having a current balancing function, characterized in that the parallel resonance half-bridge inverter. delete delete An inverter unit for switching the input power to supply a lamp driving AC power having a predetermined voltage level to the lamp; And A current balance unit connected in series between the inverter unit and the lamp to switch a lamp driving AC power from the inverter to control a current of the lamp driving AC power to maintain a current balance flowing into the lamp; The current balance unit A switch group electrically connected to an output terminal of the inverter unit to transfer or suppress an AC power for driving a lamp from the inverter unit to the lamp; And A balance switching controller providing a switching control signal for controlling the transfer and suppression operation of the switch group; The switch group A first switch electrically connected to an output terminal of the inverter unit to suppress transmission of a current of one half of one cycle of the lamp driving AC power according to the switching control signal; And A second switch electrically connected in series between the first switch and the lamp to suppress transmission of the current of the other half cycle of one cycle of the lamp driving AC power from the first switch according to the switching control signal; Lamp driving power supply having a current balancing function comprising a. The method of claim 9, wherein the switch group A first parasitic diode connected in parallel with the first switch and having a cathode connected to an output terminal of the inverter unit and an anode connected to the second switch; A first parasitic capacitor connected in parallel to the first parasitic diode and the first switch; A second parasitic diode connected in parallel with the second switch, the second parasitic diode having a cathode connected to the lamp and an anode connected to the first switch; And And a second parasitic capacitor connected in parallel to the second parasitic diode and the second switch. 10. The system of claim 9, wherein the balance switching controller A current sensing unit detecting a current of a lamp driving AC power delivered to the lamp; A control unit for providing a control signal for controlling the transfer and suppression operation of the switch group according to the detected current value; And A drive unit which amplifies the current and voltage levels of the control signal from the control unit to a current and voltage level that each switch in the switch group can drive to provide the switching control signal; Lamp driving power supply having a current balancing function comprising a. 10. The method of claim 9, The inverter unit is a power supply device for driving a lamp having a current balancing function, characterized in that the parallel resonance half-bridge inverter.

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