KR100900259B1 - Planar light-source pulse-type driving circuit adopting a transformer - Google Patents

Abstract

A transformer having a secondary winding coupled to both ends of the power supply terminal of the surface light source to supply driving voltage to the surface light source; A switching module connected to the primary winding of the transformer, the switching module including one or more switches and converting the voltages output from an input voltage source and a capacitor into pulses according to on / off operations of the one or more switches and applying them to the transformer; A diode module including one or more diodes connected in parallel to each of said one or more switches for soft switching and power recovery driving; An inductor connected to one end of a primary winding of the transformer and configured to pass a current supplied to the transformer or a current output from the transformer; And a capacitor connected between the inductor and the ground and charged with a predetermined voltage to operate as a DC voltage source. The surface light source driving circuit according to the present invention implements a function of an energy recovery circuit for optimal efficiency driving of the surface light source, and can minimize the power loss generated in the driving circuit and the energy recovery circuit. By simplifying the components put into production, the size and cost of the product can be minimized.

Surface light source, drive, transformer, pulse

Description

Planar light-source pulse-type driving circuit adopting a transformer}

The present invention relates to a pulsed surface light source driving circuit employing a transformer, and in detail, to reduce power consumption through energy recovery circuit technology to optimize the light efficiency, and to use the transformer to manufacture components for high voltage pulse driving circuits. The present invention relates to a surface light source driving circuit capable of minimizing product size and cost by simplifying.

The development of high quality light emitting technology and low cost technology for light source systems, which are being actively researched in the display and lighting market, and high efficiency technologies to reduce power consumption, can be achieved in the existing one-dimensional or none-dimensional state. This is achieved through a new planar light source, which is completely different from the method of spreading light from a light source into a plane. 1 is a photograph showing a front discharge state of a surface light source as an example of the operation of the planar light source described above. Furthermore, in preparation for the upcoming environmental regulations, new researches are being made at home and abroad on the manufacturing technology for mercury-free flat panel light sources and various driving methods for them.

Currently available is the use of xenon gas instead of mercury, which results in a significantly higher drive voltage. Cold Cathode Fluorescent Lamp (CCFL), which is used as a back light unit (BLU) light source of existing LCD screens, is diffused to utilize environmental pollution and mercury light as surface light source by using mercury. There is a disadvantage that the energy efficiency is reduced by the plate (Diffusion layer). On the contrary, in the case of the mercury-free surface type light source, mercury is not used to prepare for the upcoming environmental regulations, and further, the manufacturing cost is reduced by not requiring a diffusion plate.

 However, these light sources require a new driving waveform in the form of a pulse having a significantly shorter width than the switching period. 2 is a graph illustrating an exemplary driving waveform in the above-described pulse form. As shown in FIG. 2, the lamp voltage 1 and the lamp current 2, which are driving waveforms of the surface light source, appear in the form of pulses according to the on / off of the gating signal S. FIG. In order to drive the surface light source, a driving waveform in the form of a pulse as shown in FIG. 2 is required, and thus a need for a driving circuit for generating a driving waveform in the form of a pulse has also been raised.

In addition, an energy recovery circuit is essential to increase the power conversion efficiency of the mercury or mercury-type flat light source. However, since such a surface light source did not exist in the past, the surface light source was driven using a general-purpose high pressure pulse generator. However, this is not possible to recover energy, hard-switching at high pressure (Hard-switching) is not possible to obtain high efficiency, there was a large size problem due to many components.

The present invention for solving the above-described problems of the prior art, improves the power consumption and light efficiency, which was a problem of the driving method according to the prior art, and makes it possible to implement a high voltage pulse type drive inverter having an extremely small conduction rate with a simple structure It is also an object of the present invention to provide a pulse type surface light source driving circuit employing a transformer that can be applied to various devices by realizing high efficiency and low cost of the device through energy recovery circuit technology.

According to an aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer having a secondary winding coupled to both ends of a power terminal of a surface light source to supply a driving voltage to the surface light source; A switching module connected to the primary winding of the transformer, the switching module including one or more switches and converting the voltages output from an input voltage source and a capacitor into pulses according to on / off operations of the one or more switches and applying them to the transformer; A diode module including one or more diodes connected in parallel to each of said one or more switches for soft switching and power recovery driving; An inductor connected to one end of a primary winding of the transformer and configured to pass a current supplied to the transformer or a current output from the transformer; And the capacitor connected between the inductor and the ground and charged with a predetermined voltage to operate as a DC voltage source.

In accordance with another aspect of the present invention, a surface light source driving circuit includes: a transformer having a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A switching module connected to the primary winding of the transformer, the switching module including one or more switches and converting the voltages output from an input voltage source and a capacitor into pulses according to on / off operations of the one or more switches and applying them to the transformer; A diode module including one or more diodes connected in parallel to each of said one or more switches for soft switching and power recovery driving; An inductor connected to the diode module to pass a current supplied to the transformer or a current output from the transformer; And the capacitor connected between the inductor and the ground and charged with a predetermined voltage to operate as a DC voltage source.

In accordance with another aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer including a magnetizing inductor at a primary side, and a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A switching module connected to the primary winding of the transformer, the switching module including one or more switches and converting the voltage output from an input voltage source into pulses according to on / off operation of the one or more switches to apply the voltage to the transformer; And a diode module including one or more diodes connected in parallel to the one or more switches for soft switching and power recovery driving.

In the surface light source driving circuit according to another aspect of the present invention, the primary winding and the secondary winding are located on the primary side, and one end of the secondary winding is connected to one end of the primary winding, and the magnetization inductor and the tertiary winding are connected to the secondary side. A transformer in which the third winding is coupled to both ends of the power supply terminal of the surface light source and supplies a driving voltage to the surface light source; And at least one switch connected to each of the primary winding, the secondary winding, and the magnetizing inductor of the transformer, and converts the voltage output from the input voltage source into a pulse form according to the on / off operation of the at least one switch. Applying a switching module; And a diode module including one or more diodes connected in parallel to the one or more switches for soft switching and power recovery driving.

According to another aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer having a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A switching module connected to the primary winding of the transformer, the switching module including one or more switches and converting the voltage output from an input voltage source into pulses according to on / off operation of the one or more switches to apply the voltage to the transformer; A diode module comprising one or more diodes connected in parallel to the one or more switches for soft switching and power recovery driving; A first inductor connected to one end of a primary winding of the transformer and configured to pass a current supplied to the transformer or a current output from the transformer; And a second inductor connected to the other end of the primary winding of the transformer to pass a current supplied to the transformer or a current output from the transformer.

According to another aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer having a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A first switch including one or more switches connected to one end of the primary winding of the transformer, and converting a voltage output from an input voltage source and a capacitor into pulses according to on / off operation of the one or more switches and applying the same to the transformer; Switching module; A diode module comprising one or more diodes connected in parallel to the one or more switches for soft switching and power recovery driving; An inductor connected to one end of a primary winding of the transformer and configured to pass a current supplied to the transformer or a current output from the transformer; A second switching module connected between the inductor and the capacitor and configured to pass a bidirectional current; And the capacitor connected between the second switching module and the ground and charged with a predetermined voltage to operate as a DC voltage source.

According to another aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer having a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A first switch connected to the primary winding of the transformer and including one or more switches, and converting voltages output from an input voltage source and a capacitor into pulses according to on / off operations of the one or more switches and applying the same to the transformer; module; A diode module comprising one or more diodes connected in parallel to the one or more switches for soft switching and power recovery driving; A first inductor connected to one end of a primary winding of the transformer and configured to pass a current supplied to the transformer or a current output from the transformer; A second inductor connected to the other end of the primary winding of the transformer to pass a current supplied to the transformer or a current output from the transformer; A first capacitor connected between the first inductor and ground and charged with a predetermined voltage to operate as a DC voltage source; A second capacitor connected between the second inductor and ground and charged with a predetermined voltage to operate as a DC voltage source; And a second switching module connected between the first inductor and the first capacitor and between the second inductor and the second capacitor to pass a bidirectional current.

In accordance with another aspect of the present invention, there is provided a surface light source driving circuit comprising: a transformer including a magnetizing inductor at a primary side, and a secondary winding coupled to both ends of a power supply terminal of the surface light source to supply a driving voltage to the surface light source; A switching module including one or more switches connected to one end of the primary winding of the transformer, and converts the voltage output from the input voltage source and the capacitor in the form of a pulse according to the on / off operation of the at least one switch to apply to the transformer ; A diode module comprising one or more diodes connected in parallel to the one or more switches for soft switching the one or more switches; And the capacitor connected between the other end of the primary winding of the transformer and the ground and charged with a predetermined voltage to operate as a DC voltage source.

Using a pulsed surface light source driving circuit adopting a transformer in accordance with the present invention, high voltage pulse driving is possible by the simplest power converter structure that is responsible for boosting the voltage to high voltage for driving the surface light source in the transformer, thereby reducing the cost and The effect of efficiency increase can be acquired. In addition, the present invention enables pulse driving having an extremely short conductance rate through proper control of the switch module, and can also function as an energy recovery circuit for optimum efficiency driving when driving a surface light source. . In addition, the present invention can minimize the size and cost of the product by minimizing the power loss generated in the driving circuit and the energy recovery circuit, and simplify the components put into the circuit fabrication.

Hereinafter, with reference to the accompanying drawings looks at in detail with respect to the preferred embodiment of the present invention.

Example 1

3 is a block diagram showing a surface light source driving circuit according to a first embodiment of the present invention. The surface light source driving circuit according to the first embodiment is a unidirectional driving circuit in which the voltage applied to the surface light source has only one sign. Referring to FIG. 3, the surface light source driving circuit according to the first embodiment includes a capacitor C1, a transformer Tx, two diodes d1 and d2, two switches S1 and S2, and an inductor L1. It includes.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10.

The switching module composed of the first and second switches S1 and S2 adjusts an input voltage applied to the transformer Tx so that a pulsed voltage is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between the other end of the primary winding of the transformer Tx and ground. The first and second switches S1 and S2 periodically perform an on / off switching operation.

Diode modules composed of the first and second diodes d1 and d2 are connected in parallel to each switch so that the switches are soft switched. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to the other end of the primary winding of the transformer Tx and an anode electrode connected to ground. The first and second diodes d1 and d2 pass forward current and block reverse current.

An inductor L1 is connected between one end of the primary winding of the transformer Tx and the first capacitor C1 to pass a current.

The capacitor C1 is connected between the inductor L1 and the ground and charged to a preset voltage. The capacitor C1 has a very large capacitance and operates as a direct current voltage source supplying a voltage to the primary winding of the transformer Tx.

The operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 4 to 7. 4 is a timing diagram showing the operation of the surface light source driving circuit according to the first embodiment of the present invention. In each waveform of the timing diagrams included in the present specification, resonance due to parasitic components was ignored. Referring to FIG. 4, the surface light source driving circuit according to the first embodiment is driven while the four modes are periodically circulated according to on / off of the first and second switches S1 and S2.

5 to 7 are diagrams showing equivalent circuits of the surface light source driving circuit in each mode. First, the first and second switches S1 and S2 are OFF before mode 1 starts, so there is no current flow. At this time, the mode 1 starts while the second switch S2 is turned on (soft switching).

Mode 1: Referring to Fig. 5, Mode 1 in which the first switch S1 is off and the second switch S2 is on will be described. When the second switch S2 is turned on, the voltage of the capacitor C1 is applied to the inductor L1, so that the inductor current i _L starts to increase. Since the capacitor C1 has a large capacitance, the capacitor C1 operates as a DC voltage source Vc that outputs a voltage of Vc substantially. The current exits capacitor C1 and is freewheeled through second switch S2 via transformer Tx. When the voltage across the transformer Tx primary is equal to Vcc due to resonance between the inductor L1 and the capacitor component of the surface light source 10 and the parasitic capacitor on the circuit, the first diode d1 is turned on to obtain soft switching. When the first diode d1 is turned on, the current i _L flows to the input voltage source Vcc, and the ramp voltage V _lamp increased by the turns ratio (1: n) while the transformer Tx primary side voltage is fixed at Vcc. ) Is also fixed. When the primary side voltage of the transformer Tx does not reach Vcc, the first diode d1 does not conduct and goes to the next mode while the primary side voltage is close to Vcc.

Mode 2: Referring to FIG. 6, Mode 2 in which the first and second switches S1 and S2 are turned on will be described. While the first diode d1 is turned on, the first switch S1 is also conducted to obtain soft switching. Since voltage V _cc of the input voltage source is much higher than the voltage (Vc) of the capacitor (C1), the continued reverse voltage to the inductor (L1) is caught, the current (i _L) is reduced while the direction change. As soon as the direction of the current changes, the first diode d1 is turned off and the current flows to the first switch S1. A current is supplied to the surface light source 10 by a current n · i _lamp flowing through the first switch S1 to the transformer Tx, and light emission occurs in mode 2. FIG.

Mode 3: Referring to FIG. 7, Mode 3 in which the first switch S1 is off and the second switch S2 is on will be described. When the section in which the surface light source 10 emits light ends, the first switch S1 is turned off. As soon as the first switch S1 is turned off, the current flowing into the surface light source 10 is cut off, so the surface light source is turned off, and since the current cannot be supplied from the input voltage source Vcc through the first switch S1, As the charge accumulated in the surface light source 10 is removed through the transformer Tx, the lamp voltage V _lamp , which is the voltage of the surface light source 10, is drastically reduced. In addition, the current i _L is reduced to the capacitor C1. Since the charge in the surface light source 10 is reduced back to the capacitor C1 operating as the voltage source Vc, energy can be recovered.

When the surface light source voltage V _lamp reaches near zero, the surface light source voltage V _lamp is fixed to zero while the second diode d2 is turned on, and the primary side voltage of the transformer Tx is also fixed to zero. The second switch S2 is turned off while current flows to the diode d2 to obtain soft switching. If the voltage of the transformer Tx does not reach zero, the second switch S2 is forcibly turned off (hard switching).

Mode 4: Mode 4 is a state in which the first and second switches S1 and S2 are both off and no current flows. After mode 4, it repeats from mode 1 again.

The circuit according to the first embodiment of the present invention described above uses a transformer as an ideal boosting element so that leakage and magnetization inductance do not participate in the main operation, and the input voltage source Vcc of the front end is more than several hundred volts (V). There is an advantage that can be designed so as not to increase the ramp voltage.

Example 2

8 is a block diagram showing a surface light source driving circuit according to a second embodiment of the present invention. Referring to FIG. 8, the surface light source driving circuit according to the second embodiment includes a circuit in which a second capacitor C2 is added to the surface light source driving circuit according to the first embodiment described above with reference to FIGS. 3 to 7. to be.

The second capacitor C2 is connected between the inductor L1 and the input voltage source Vcc and charged to a preset voltage. In driving the surface light source 10, the second capacitor C2 operates as a DC voltage source like the first capacitor C1. Since the operation of the surface light source driving circuit according to the second embodiment is the same as the operation of the surface light source driving circuit according to the first embodiment described with reference to FIGS. 3 to 7, it will be easily understood by those skilled in the art. It will be omitted.

Example 3

9 is a block diagram showing a surface light source driving circuit according to a third embodiment of the present invention. The surface light source driving circuit according to the third embodiment is a circuit in which the current injection mode for soft switching is added to the surface light source driving circuit according to the first embodiment described above.

As shown in FIG. 9, the surface light source driving circuit according to the third embodiment is a circuit in which the third switch S3 is added to the surface light source driving circuit according to the first embodiment described above with reference to FIGS. 3 to 7. to be. The third switch S3 is connected between one end of the primary winding of the transformer Tx and the ground to periodically perform an on / off switching operation.

An operation of the surface light source driving circuit according to the third embodiment will be described with reference to FIG. 10 which is a timing diagram showing the operation of the surface light source driving circuit. As shown, the surface light source driving circuit according to the third embodiment is the same as the first embodiment of the mode 1 to mode 4 by the operation of the first and second switches (S1, S2) of the third switch (S3) Five driving modes of mode 0 by the operation are cycled periodically.

Mode 0: Referring to FIG. 11, Mode 0 in which the third switch S3 is on and the first and second switches S1 and S2 are off will be described. When the third switch S3 is turned on, current due to the voltage Vc of the capacitor C is refluxed through the inductor L1 and the third switch S3. Therefore, the voltage Vc of the capacitor C is applied to the inductor L1 so that the current i _L constantly rises. After the value of the current i _L flowing through the inductor L1 is uniformly formed, the second switch S2 is turned on and mode 1 starts. Since the operation of the surface light source driving circuit according to the third embodiment in Modes 1 to 4 is the same as the operation of the surface light source driving circuit according to the first embodiment described above, a detailed description thereof will be omitted.

The surface light source driving circuits according to the first and second embodiments attempted soft switching only by voltage resonance by the capacitor C, but the surface light source driving circuit according to the third embodiment uses the inductor L1 in mode 0. By increasing the current of the constant and then injecting it into the resonance, there is an advantage that can compensate for the energy insufficient for soft switching. 9 illustrates a circuit in which a third switch is added to the surface light source driving circuit according to the first embodiment shown in FIG. 3, but a third switch is applied to the surface light source driving circuit according to the second embodiment shown in FIG. 8. It is obvious that the same effect can be obtained even if added.

In the first to third embodiments described with reference to FIGS. 3 to 10, as a unidirectional driving circuit, a pulse of an output voltage (lamp voltage) is generated in only one direction, but an output voltage ( Pulses of the ramp voltage) may be generated in both directions. Hereinafter, the bidirectional driving will be described with reference to FIGS. 9 to 16.

Example 4

12 is a block diagram showing a surface light source driving circuit according to a fourth embodiment of the present invention. The surface light source driving circuit according to the fourth embodiment is a surface light source driving circuit which can configure the sign of the voltage applied to the surface light source in both directions using one inductor. Referring to FIG. 9, the surface light source driving circuit according to the fourth embodiment includes an inductor L, a transformer Tx, a capacitor C, five diodes d0 to d4, and five switches S0 to S4. ).

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10.

The switching module composed of the connection switch S0 and the first to fourth switches S1 to S4 controls an input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the connection switch S0, and the connection switch S0 is connected between the first switch S1 and the input voltage source Vcc. Connected. The second switch S2 is connected between one end of the primary winding of the transformer Tx and ground, and the third switch S3 is connected between the other end of the primary winding of the transformer Tx and the inductor L. The fourth switch S4 is connected between the other end of the primary winding of the transformer Tx and the ground. The five switches S0 to S4 periodically perform an on / off switching operation.

The diode module including the connection diode d0 and the first to fourth diodes d1 to d4 serves to soft switch each switch. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the anode electrode of the connection diode d0. In the connection diode d0, an anode electrode is connected to the cathode electrode of the first diode d1, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx and an anode electrode connected to ground. In the third diode d3, an anode electrode is connected to the other end of the primary winding of the transformer Tx, and a cathode electrode is connected to the inductor L. The fourth diode d4 has a cathode electrode connected to the other end of the primary winding of the transformer Tx, and an anode electrode connected to ground. The five diodes d0 to d4 pass forward current and block reverse current.

The inductor L is connected between the anode electrode of the connection diode d0, the cathode electrodes of the first and third diodes d1 and d3, and the capacitor C, and outputs the current i from the capacitor C. _L ) or through the current output from the transformer (Tx) direction.

The capacitor C is connected between the inductor L and ground and charged to a preset voltage. The capacitor C has a very large capacitance and operates as a direct current voltage source for supplying a voltage to the transformer Tx.

The operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 13 to 19 to be described later. 13 is a timing diagram showing the operation of the surface light source driving circuit according to the fourth embodiment of the present invention. Referring to FIG. 13, the surface light source driving circuit according to the fourth embodiment is driven while the eight modes are periodically cycled according to the on / off of the connection switch S0 and the first to fourth switches S1 to S4. do.

14 to 19 are diagrams showing equivalent circuits in each mode of the surface light source driving circuit according to the fourth embodiment. Operation in each mode of the surface light source driving circuit according to the fourth embodiment is the same as in the first embodiment, and only the path through which the current flows is different.

Mode 1: Referring to FIG. 14, Mode 1 in which the connection switch S0, the second and third switches S2 and S3 are turned off and the first and fourth switches S1 and S4 are turned on will be described. do. Since the capacitor C has a very large capacitance, the capacitor C operates substantially as the voltage source Vc, and as the voltage Vc is applied to the inductor L, the current i _L starts to increase. The current i _L exits the capacitor C, passes through a transformer Tx, and is refluxed through the fourth switch C4. When the voltage across the transformer Tx primary is equal to Vcc due to the resonance between the inductor L and the capacitor component of the surface light source 10 and the parasitic capacitor on the circuit, the connecting diode d0 is turned on (soft switching), Current i _L flows to the input voltage source Vcc. At this time, while the primary voltage of the transformer Tx is fixed to Vcc, the lamp voltage V _lamp increased by the turns ratio by the transformer Tx is also fixed. If the voltage does not reach Vcc, the connection diode d0 goes to mode 2 without the conduction while the voltage is close to Vcc.

Mode 2: Referring to FIG. 15, Mode 2 in which the second and third switches S2 and S3 are off and the connection switch S0 and the first and fourth switches S1 and S4 are turned on will be described. do. Soft switching is obtained by conducting the connection switch SO while the connection diode do is turned on. Since the voltage Vcc of the input voltage source is much higher than the capacitor voltage Vc, the inductor L is continuously subjected to reverse voltage, so that the current i _L continues to decrease and change direction. As soon as the direction of the current changes, the connection diode d0 is turned off and the current flows to the connection switch S0. A current is supplied to the surface light source 10 through a current n · i _lamp toward the transformer Tx through the connection switch S0, and light emission of the surface light source 10 occurs in mode 2.

Mode 3: Referring to FIG. 16, Mode 3 in which the connection switch S0, the second and third switches S2 and S3 are turned off and the first and fourth switches S1 and S4 are turned on will be described. do. After the section in which the surface light source 10 emits light in mode 2, the connection switch S0 is turned off. As soon as the connection switch S0 is turned off, the current flowing into the surface light source 10 is cut off, so the surface light source is turned off, and since the current cannot be supplied through the connection switch S0 from the input voltage source, the transformer Tx. The lamp voltage (V _lamp ) is drastically reduced while extracting the charge accumulated in the surface light source 10 through. In addition, the current i _L is reduced to the capacitor C. The charges in the surface light source 10 are recovered by the capacitor C again, whereby an energy recovery effect can be obtained.

When the lamp voltage V _lamp reaches near zero, the second and third diodes d2 and d3 are turned on and the lamp voltage V _lamp is fixed at zero, and the primary side voltage of the transformer Tx is also zero. It is fixed. Soft switching is obtained by turning off the first and fourth switches S1 and S4 while current flows to the second and third diodes d2 and d3. When the primary side voltage of the transformer Tx does not reach zero, the first and fourth switches S1 and S4 are forcibly turned off.

Mode 4: In mode 4, both the connection switch SO and the first to fourth switches S1 to S4 are turned off. Mode 4 is a rest period without current flow, and mode 5 to mode 8 begins after mode 4.

17 to 19, the operation in the mode 5 to mode 8 of the surface light source driving circuit according to the fourth embodiment is the same as the operation in the mode 1 to mode 4 except for the sign of the lamp voltage (V _lamp ). Therefore, detailed description will be omitted since those skilled in the art can easily understand.

The surface light source driving circuit according to the fourth embodiment of the present invention described above is capable of driving in both directions using one inductor, and the current frequency of the inductor and the connection switch is applied to a conventional full-bridge circuit. There is an advantage that is doubled.

Example 5

20 is a timing diagram showing the operation of the surface light source driving circuit according to the fifth embodiment of the present invention. The surface light source driving circuit according to the fifth embodiment adds a current injection mode for soft switching to the surface light source driving circuit according to the fourth embodiment. The configuration of the surface light source driving circuit according to the fifth embodiment is the same as that of the surface light source driving circuit according to the fourth embodiment, except that only the operation of each switch is different as shown in FIG. 20.

Referring to FIG. 20, in the surface light source driving circuit according to the fifth embodiment, before the mode 1 starts, the mode 0 in which the first and second switches S1 and S2 are turned on is present, so that Five modes are driven by cycling periodically. 21 is a configuration diagram showing an equivalent circuit in mode 0 of the surface light source driving circuit according to the fifth embodiment.

Mode 0: Referring to FIG. 21, Mode 0 in which the first and second switches S1 and S2 are on and the third and fourth switches S3 and S4 are off will be described. When the first and second switches S1 and S2 are turned on, current due to the voltage Vc of the capacitor C is refluxed through the inductor L1 and the first and second switches S1 and S2. Accordingly, the voltage Vc of the capacitor C is applied to the inductor L1 and the current i _L constantly rises. After the value of the current i _L flowing through the inductor L1 is uniformly formed, the third switch S3 is turned on and mode 1 starts. Since the operation of the surface light source driving circuit according to the fifth embodiment in the modes 1 to 4 is the same as the operation of the surface light source driving circuit according to the fourth embodiment, detailed description thereof will be omitted.

After mode 4, mode 4 'is started in which the first and second switches S1 and S2 are on and the third and fourth switches S3 and S4 are off. The operation in mode 4 'is the same as the operation in mode 0 described above, and after mode 4', mode 5 starts. Since the operation of the surface light source driving circuit according to the fifth embodiment in the mode 5 to mode 8 is the same as the operation of the surface light source driving circuit according to the fourth embodiment described above, detailed description thereof will be omitted.

 The surface light source driving circuit according to the fifth embodiment injects the current of the inductor L1 into resonance in modes 0 and 4 ', thereby replenishing energy insufficient for soft switching. In FIG. 20, a timing diagram in which mode 0 is driven by turning on the first and second switches S1 and S2 and turning off the third and fourth switches S3 and S4 is illustrated. It is apparent that the same effect can be obtained when the mode 0 is driven by turning on S3 and S4 and turning off the first and second switches S1 and S2.

Example 6

22 is a block diagram showing a surface light source driving circuit according to a sixth embodiment of the present invention. The surface light source driving circuit according to the sixth embodiment is a surface light source driving circuit for implementing bidirectional driving by using an input voltage source (without a capacitor) and a magnetizing inductor of a transformer. Referring to FIG. 22, the surface light source driving circuit according to the sixth embodiment includes a transformer Tx, four diodes d1 to d4, and four switches S1 to S4.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10. The transformer Tx includes a magnetizing inductor L _M on the primary side.

In the sixth embodiment, the magnetizing inductor L _M of the transformer Tx acts as a current source, acting as a resonant energy source. In the above-described first to fifth embodiments, the transformer Tx is designed to boost voltage, so that the inductance of the magnetizing inductor L _M is designed to be as large as possible to operate in an ideal transformer form, whereas in the sixth embodiment, the transformer Tx is designed to be large. ) Appropriately configures the value of the magnetizing inductor L _M and drives it to resonate with the parasitic capacitance of the circuit. When the inductance of the magnetizing inductor L _M becomes too large, the resonance period becomes long, and thus the rise and fall times of the pulse become long, thereby losing the function as a pulse waveform. Thus magnetizing inductor in consideration of the voltage and frequency, conduction rate, such as applied to the (L _M) to be designed for a transformer (Tx) have an inductance value of an appropriate magnetizing inductor (L _M).

The switching module including the first to fourth switches S1 to S4 controls an input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. The third switch S3 is connected between the other end of the primary winding of the transformer Tx and the input voltage source Vcc, and the fourth switch S4 is connected to the primary winding of the transformer Tx. It is connected between the other end and ground. The four switches S1 to S4 periodically perform an on / off switching operation.

The diode modules composed of the first to fourth diodes d1 to d4 serve to soft switch the switches S1 to S4. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx and an anode electrode connected to ground. In the third diode d3, an anode electrode is connected to the other end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The fourth diode d4 has a cathode electrode connected to the other end of the primary winding of the transformer Tx, and an anode electrode connected to ground. Four diodes (d1 to d4) serve to pass forward current and block reverse current.

The operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 23 to 27 to be described later. Fig. 23 is a timing diagram showing the operation of the surface light source driving circuit according to the sixth embodiment of the present invention. Referring to FIG. 23, the surface light source driving circuit according to the sixth embodiment is driven while the four modes are periodically cycled according to on / off of the first to fourth switches S1 to S4.

24 and 25 are diagrams showing equivalent circuits in Mode 1 and Mode 2 of the surface light source driving circuit according to the sixth embodiment. The surface light source driving circuit according to the sixth embodiment implements an energy recovery function and a soft switching function by using the magnetizing inductor L _M of the transformer Tx. The operation in each mode is as follows.

Before mode 1 starts, the first and third switches S1 and S3 are off and the second and fourth switches S2 and S4 are in an on state. At this time, the current i _Lm is refluxed through the second and fourth switches S2 and S4. When the second switch S2 is turned off, the inductor current i _Lm conducts the first diode d1, and at the same time or slightly later, the mode 1 starts.

Mode 1: Referring to FIG. 24, Mode 1 in which the second and third switches S2 and S3 are turned off and the first and fourth switches S1 and S4 are turned on will be described. Soft switching is obtained by turning on the first switch S1 while the first diode d1 is turned on. When the first switch S1 is turned on, the direction of the current is changed so that the first diode d1 is turned off and the current flows to the first switch S1. Then, a reverse voltage is applied to the magnetizing inductor L _M by the voltage of the input voltage source Vcc, and the value of the inductor current i _Lm decreases and then changes direction. Current is supplied to the surface light source 10 through the first switch S1, and the surface light source 10 emits light in Mode 1.

Mode 2: Referring to FIG. 25, Mode 2 in which the first and third switches S1 and S3 are off and the second and fourth switches S2 and S4 are on will be described. When the section in which the surface light source 10 emits light in mode 1 ends, the first switch S1 is turned off. As soon as the first switch S1 is turned off, the current flowing into the surface light source 10 is cut off so that the surface light source 10 is turned off, and the current is supplied from the input voltage source Vcc through the first switch S1. Therefore, the lamp voltage (V _lamp ) is drastically reduced while removing the charge accumulated in the surface light source 10 through the transformer (Tx). When the lamp voltage V _lamp reaches near zero, the second diode d2 is turned on and the transformer Tx primary side voltage is fixed to zero. Soft switching is obtained by turning on the second switch S2 while the inductor current i _Lm flows to the second diode d2. When the voltage of the transformer Tx does not reach zero, the second switch S2 is forcibly turned on. Thereafter, the inductor current i _Lm is refluxed through the second and fourth switches S2 and S4.

Mode 3: Operation in Mode 3, where the first and fourth switches S1 and S4 are off, and the second and third switches S2 and S3 are on, operates in Mode 1 and the surface light source 10 Since only the direction of the current and the lamp voltage (V _lamp ) are reversed, and the operating principle is the same, a detailed description will be omitted since a person skilled in the art can easily understand.

Mode 4: the first and third switches (S1, S3) is off and the second and fourth switches (S2, S4) is turned on the mode of operation from 4 operates and the inductor current in the mode 2 (i _Lm Since only the direction is reversed and the operating principle is the same, a detailed description will be omitted since a person skilled in the art can easily understand.

In the surface light source driving circuit according to the sixth embodiment described above, the surface light source is driven in both directions in modes 1 and 3, and the configuration and operation of the circuit are simple. In addition, the magnetization inductor of the transformer is used as a current source, and the transformer itself is used as an ideal boosting element so that the leakage inductance does not participate in the main operation, and the ramp voltage at which the input voltage source (Vcc) of the front end is several hundred volts (V) or more. Designed not to go up, the overall system configuration has the advantage of simplicity.

Example 7

Fig. 26 is a configuration diagram showing a surface light source driving circuit according to the seventh embodiment of the present invention. The surface light source driving circuit according to the seventh embodiment is a circuit modified from the surface light source driving circuit according to the sixth embodiment, and has the same four operating modes and similar operation waveforms as the surface light source driving circuit according to the sixth embodiment. Magnetization inductors are used to implement energy recovery and soft switching. However, since each switch uses a push-pull type rather than a bridge type, no high-side driver is required.

Referring to FIG. 26, the surface light source driving circuit according to the seventh embodiment includes a transformer Tx, four diodes d1 to d4, and four switches S1 to S4.

The transformer Tx has a primary winding and a secondary winding on the primary side, a tertiary winding and a magnetizing inductor L _{M on the} secondary side, and both ends of the tertiary winding are both ends of the power terminal of the surface light source 10. It is coupled to supply the driving voltage to the surface light source (10). That is, the voltage applied across both the primary and secondary windings is induced in the both ends of the primary winding in proportion to the (primary: tertiary) or (secondary: tertiary) winding ratio of the transformer Tx, so that the surface light source ( 10) is applied as a driving voltage.

The driving mode according to the operation of each switch of the surface light source driving circuit according to the seventh embodiment is the same as the driving mode of the surface light source driving circuit according to the sixth embodiment shown in FIG. The operation in each mode is as follows.

Before mode 1 starts, the first and third switches S1 and S3 are off and the second and fourth switches S2 and S4 are in an on state. At this time, the current i _Lm is refluxed through the second and fourth switches S2 and S4. When the second switch S2 is turned off, the inductor current i _Lm conducts the first diode d1, and at the same time or slightly later, the mode 1 starts.

Mode 1: Referring to FIG. 27, Mode 1 in which the second and third switches S2 and S3 are turned off and the first and fourth switches S1 and S4 are turned on will be described. The operation in mode 1 of the surface light source driving circuit according to the seventh embodiment is similar to the operation in mode 1 of the surface light source driving circuit according to the sixth embodiment. A first switch (S1) that when the on-current is out of the voltage source (Vcc) and refluxed through a first switch (S1), magnetizing inductor (L _M) the current (i _Lm) induced in the fourth switch (S4) Reflux through. In mode 1, light emission of the surface light source 10 occurs.

Operation in the mode 2 and the mode 4 is the same as the surface light source driving circuit according to the sixth embodiment described above with reference to FIG. Also, the operation in mode 3 is the same as the operation in mode 1 except that the direction of the current i _Lm applied to the magnetizing inductor L _M is reversed. Therefore, a detailed description of the operation in the driving modes other than the mode 1 is omitted.

The surface light source driving circuit according to the seventh embodiment may further include a reset circuit for preventing saturation of the transformer Tx. The reset circuit is a circuit for making a sum of voltages applied to a transformer to zero in one period to prevent the DC component of the voltage applied to the transformer Tx from accumulating and saturation. It can be configured as. In the seventh embodiment, the reset circuit may be connected in series to the magnetizing inductor L _M located at the secondary side of the transformer Tx.

In the surface light source driving circuit according to the seventh embodiment described above, unlike the conventional push-pull inverter, the third and fourth switches S3 and S4 for pulse driving are used. Instead of using a high side driver as compared to a full bridge circuit, the voltage applied to the first and second switches S1 and S2 is twice the input voltage and is applied to the third and fourth switches S3 and S4. The voltage is a voltage changed by the turn ratio from the input voltage.

Example 8

28 is a block diagram showing a surface light source driving circuit according to an eighth embodiment of the present invention. Referring to FIG. 28, the surface light source driving circuit according to the eighth embodiment includes an inductor L, a transformer Tx, four diodes d1 to d4, and four switches S1 to S4.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10. One end of the primary winding of the transformer Tx is connected to ground.

The switching module including the first to fourth switches S1 to S4 controls an input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S3 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. The third switch S3 is connected between the inductor L and the input voltage source Vcc, and the fourth switch S4 is connected between the inductor L and the ground. The four switches S1 to S4 periodically perform an on / off switching operation.

Diode modules composed of first to fourth diodes d1 to d4 are connected to each switch in parallel to soft switch the switches. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx, and an anode electrode connected to ground. In the third diode d3, an anode electrode is connected to the inductor L, and a cathode electrode is connected to the input voltage source Vcc. The fourth diode d4 has a cathode electrode connected to the inductor L, and an anode electrode connected to the ground. Four diodes (d1 to d4) serve to pass forward current and block reverse current.

An operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 29 to 33. 29 is a timing diagram showing the operation of the surface light source driving circuit according to the eighth embodiment of the present invention. Referring to FIG. 29, the surface light source driving circuit according to the eighth embodiment is driven while the four modes are periodically cycled according to on / off of the first to fourth switches S1 to S4.

30 to 33 are block diagrams showing equivalent circuits in the respective modes of the surface light source driving circuit according to the eighth embodiment. The operation in each mode is as follows.

First, before the start of mode 1, the first, third and fourth switches S1, S3, S4 are off and only the second switch S2 is continuously on, so there is no current flow in the circuit. . At this time, the mode 1 starts while the third switch S3 is turned on. When the third switch S3 is turned on, the second switch S2 is turned off at the same time or with a slight time difference.

Mode 1: Referring to FIG. 30, Mode 1 in which the first, second and fourth switches S1, S2, S4 are off and the third switch S3 is on will be described. When the third switch S3 is turned on, the voltage Vcc is applied to the inductor L, and the current i _L starts to increase. The current i _L exits the voltage source Vcc and is refluxed via the transformer Tx. When the voltage across the transformer Tx primary is equal to Vcc due to resonance between the inductor L and the capacitor component of the surface light source 10 and the parasitic capacitor on the circuit, the first diode d1 is turned on to obtain soft switching. do. When the first diode d1 is turned on, the current i _L flows into the input voltage source Vcc and the voltage of the ramp T1 is increased by the turns ratio at the primary voltage while the primary voltage of the transformer Tx is fixed at Vcc. (V _lamp ) is also fixed. When the primary side voltage of the transformer Tx does not reach Vcc, the first diode d1 is switched to mode 2 without conduction while the voltage is close to Vcc.

Mode 2: Referring to FIG. 31, Mode 2 in which the first switch S1 is on and the second to fourth switches S2 to S4 are off will be described. Soft switching is obtained by turning on the first switch S1 while the first diode d1 is turned on. Thereafter, the current i _Tx from the input voltage source Vcc passes through the first switch S1 and flows in the direction of the transformer Tx, thereby causing light emission to the surface light source 10. The current i _L is refluxed while the value stays near zero.

Mode 3: Referring to Fig. 32, Mode 3 in which the first to third switches S1 to S3 are turned off and the fourth switch S4 is turned on will be described. When the section in which the surface light source 10 emits light ends, the first switch S1 is turned off. As soon as the first switch S1 is turned off, since the current flowing into the surface light source 10 is cut off, the surface light source 10 is turned off, and a reverse voltage is applied to the inductor L, so that the current i _L is reversed. It starts to flow. The lamp voltage V _lamp rapidly decreases as the current i _L extracts the charge accumulated in the surface light source 10 through the transformer Tx.

Thereafter, while turning off the fourth switch S4, the current i _L is redirected to the third diode d3 and is reduced to the input voltage source Vcc. At this time, the charge in the surface light source 10 is reduced back to the input voltage source (Vcc), thereby implementing an energy recovery function. When the lamp voltage V _lamp of the surface light source reaches near zero, the lamp voltage V _lamp is fixed at zero while the second diode d2 is turned on, and the primary side voltage of the transformer Tx is also fixed at zero. . Soft switching is obtained by turning on the second switch S2 while the current i _L flows to the second diode d2. If the primary voltage of the transformer Tx does not reach 0, the second switch S2 is forcibly turned on to perform hard switching.

Mode 4: Mode 4, in which the equivalent circuit is shown in FIG. 33, has no idle current because the first, third and fourth switches S1, S3, S4 are off and the second switch S2 is on. to be. After Mode 4, Mode 1 is repeated.

The surface light source driving circuit according to the eighth embodiment described above is characterized in that the light emission time (mode 2) and resonance time (mode 1, mode 3) of the surface light source can be easily adjusted. In addition, by using a transformer as an ideal boost element, leakage and magnetizing inductance do not participate in the main operation, and the design can be designed so that the input voltage source (Vcc) of the front end does not rise to the lamp voltage which is several hundred volts (V) or more. There is this.

Example 9

34 is a timing diagram showing the operation of the surface light source driving circuit according to the ninth embodiment of the present invention. The surface light source driving circuit according to the ninth embodiment adds a current injection mode for soft switching to the surface light source driving circuit according to the eighth embodiment. The configuration of the surface light source driving circuit according to the ninth embodiment is the same as that of the surface light source driving circuit according to the eighth embodiment described above, except that only the operation of each switch is different.

Referring to FIG. 34, in the surface light source driving circuit according to the ninth embodiment, before the mode 1 starts, the second and third switches S2 and S3 are turned on and the first and fourth switches S1 and S4 are turned on. There is a mode 0 that is off, and a mode 2 'exists between the mode 2 and the mode 3, wherein the first and fourth switches S1 and S4 are on and the second and third switches S2 and S3 are off. . The surface light source driving circuit according to the ninth embodiment is driven while the six modes of modes 0 to 4 and mode 2 'are cyclically cycled. 35 and 36 are diagrams showing equivalent circuits in mode 0 and mode 2 'of the surface light source driving circuit according to the ninth embodiment, respectively.

Mode 0: Referring to FIG. 35, Mode 0 in which the second and third switches S2 and S3 are on and the first and fourth switches S1 and S4 are off will be described. When the second and third switches S2 and S3 are turned on, current flows from the input voltage source Vcc to the third switch S3, the inductor L and the second switch S2 in turn. Accordingly, the input voltage Vcc is applied to the inductor L1 and the current i _L constantly rises. After the value of the current i _L flowing through the inductor L1 is uniformly formed, the second switch S2 is turned off, and mode 1 starts. Since the operation of the surface light source driving circuit according to the ninth embodiment in the mode 1 and the mode 2 is the same as the operation of the surface light source driving circuit according to the eighth embodiment described above, a detailed description thereof will be omitted.

After mode 2, mode 2 'is started in which the first and fourth switches S1 and S4 are on and the second and third switches S2 and S3 are off. Since the operation in the mode 2 'is the same as the operation in the mode 0 described above, only the direction of the current i _L is reversed, and thus a detailed description thereof is omitted. After the mode 2 ', the mode 3 starts with the first switch S1 turned off. Since the operation of the surface light source driving circuit according to the ninth embodiment in the mode 3 and the mode 4 is the same as the operation of the surface light source driving circuit according to the eighth embodiment described above, detailed description thereof will be omitted.

The surface light source driving circuit according to the ninth embodiment injects the current of the inductor (L) to the resonance in the mode 0 and the mode 2 'has the advantage that can compensate for the energy insufficient for soft switching.

Example 10

37 is a block diagram showing a surface light source driving circuit according to a tenth embodiment of the present invention. Referring to FIG. 37, the surface light source driving circuit according to the tenth embodiment may include first and second inductors L1 and L2, a transformer Tx, eight diodes d1 to d8, and eight switches S1 to. S8).

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10.

The switching module including the first to eighth switches S1 to S8 controls the input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. The third switch S3 is connected between the other end of the primary winding of the transformer Tx and the input voltage source Vcc, and the fourth switch S4 is connected to the primary winding of the transformer Tx. It is connected between the other end and ground. The four switches S1 to S4 periodically perform an on / off switching operation.

Diode modules composed of first to eighth diodes d1 to d8 are connected to each switch in parallel to soft switch the switches. The first diode d1 has an anode electrode connected to one end of a primary winding of the transformer Tx and a cathode electrode connected to an input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx and an anode electrode connected to ground. In the third diode d3, an anode electrode is connected to the other end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The fourth diode d4 has a cathode electrode connected to the other end of the primary winding of the transformer Tx, and an anode electrode connected to ground. The four diodes d1 to d4 pass forward current and block reverse current.

Meanwhile, the first inductor L1 is connected to one end of the primary winding of the transformer Tx, and the second inductor L2 is connected to the other end of the primary winding of the transformer Tx. The fifth to eighth diodes d5 to d8 and the fifth to eighth switches S5 to S8 are connected to the first and second inductors L1 and L2.

The fifth switch S5 is connected between the first inductor L1 and the input voltage source Vcc, and the sixth switch S6 is connected between the first inductor L1 and ground and the seventh switch ( S7 is connected between the second inductor L2 and the input voltage source Vcc, and an eighth switch S8 is connected between the second inductor L2 and ground. The four switches S5 to S8 also periodically perform on / off switching operations.

A fifth diode d5 has an anode electrode connected to the first inductor L1 and a cathode electrode connected to an input voltage source Vcc. In the sixth diode d6, a cathode electrode is connected to the first inductor L1, and an anode electrode is connected to ground. In the seventh diode d7, an anode electrode is connected to the second inductor L2, and a cathode electrode is connected to the input voltage source Vcc. In the eighth diode d8, a cathode electrode is connected to the second inductor L2, and an anode electrode is connected to ground. The four diodes d5 to d8 also serve to pass forward current and block reverse current.

An operation of the surface light source driving circuit according to the tenth embodiment of the present invention configured as described above will be described with reference to FIG. 38 to be described later. 38 is a timing diagram showing the operation of the surface light source driving circuit according to the tenth embodiment of the present invention. Referring to FIG. 38, the surface light source driving circuit according to the tenth embodiment is driven while the eight modes of the modes 1 to 8 are periodically cycled according to the on / off of the first to eighth switches S1 to S8. do.

In the tenth embodiment, the operation of the surface light source driving circuit in each mode is the same as the operation of the eighth embodiment described with reference to Figs. However, the left and right bridges of the full bridge circuit are switched 180 degrees with respect to the surface light source 10, so that the lamps of the surface light source 10 are changed in accordance with the operation of the second, third, seventh and eighth switches. The only difference is that the voltage V _lamp alternates between a positive and a negative value. Therefore, since the operation of the surface light source driving circuit according to the tenth embodiment can be easily understood by those skilled in the art from the surface light source driving circuit according to the eighth embodiment, a detailed description thereof will be omitted.

The surface light source driving circuit according to the tenth embodiment may further include a reset circuit for preventing saturation of the transformer Tx. As the reset circuit, various types of circuits known in the art may be used, and most simply, may be composed of one capacitor connected in series to the primary side of the transformer Tx. Here, the reset circuit connected to the surface light source driving circuit according to the tenth embodiment has been described, but the reset circuit may be included in all of the surface light source driving circuits according to other embodiments of the present invention.

Example 11

Fig. 39 is a timing diagram showing the operation of the surface light source driving circuit according to the eleventh embodiment of the present invention. The surface light source driving circuit according to the eleventh embodiment adds a current injection mode for soft switching to the surface light source driving circuit according to the tenth embodiment. The configuration of the surface light source driving circuit according to the eleventh embodiment is the same as that of the surface light source driving circuit according to the tenth embodiment described above, except that only the operation of each switch is different as shown in FIG.

Referring to FIG. 39, in the surface light source driving circuit according to the eleventh embodiment, the mode 0 in which the second, fourth and fifth switches S2, S4, and S5 are on and the remaining switches are off before the mode 1 starts. Is present, and there is a mode 2 'between the first and fourth switches S1, S4, and S6 that are on and the other switches are off between modes 2 and 3. In addition, between the mode 4 and the mode 5, the second, fourth and seventh switch (S2, S4, S7) is on and the other switch is off mode 4 'is present, and between the mode 6 and mode 7 There is a mode 6 'in which the third and eighth switches S2, S3, S8 are on and the remaining switches are off. The surface light source driving circuit according to the eleventh embodiment is driven while the 12 modes of modes 0 to 8, mode 2 ', mode 4' and mode 6 'are periodically cycled.

In the eleventh embodiment, the operation of the surface light source driving circuit in each mode is the same as that of the ninth embodiment described with reference to FIGS. 34 to 36. However, the left and right bridges of the full bridge circuit are switched 180 degrees with respect to the surface light source 10, so that the second, third, seventh and eighth switches S2, S3, S7, and S8 operate. The only difference is that the _lamp voltage V _lamp of the surface light source 10 alternates between a positive value and a negative value. Therefore, since the operation of the surface light source driving circuit according to the eleventh embodiment can be easily understood by those skilled in the art from the surface light source driving circuit according to the ninth embodiment, a detailed description thereof will be omitted.

Example 12

40 is a block diagram showing a surface light source driving circuit according to a twelfth embodiment of the present invention. Referring to FIG. 40, the surface light source driving circuit according to the twelfth embodiment includes an inductor L1, a capacitor C, a transformer Tx, two diodes d1 and d2, and four switches S1 to S4. It includes.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10. The other end of the primary winding of the transformer Tx is connected to ground.

The inductor L1 is connected to one end of the primary winding of the transformer Tx, and passes the current directed to the transformer Tx and the current output from the transformer Tx.

The first switching module composed of the first and second switches S1 and S2 controls the input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. Is connected to. In addition, the second switching module composed of the third and fourth switches S3 and S4 passes current in both directions according to the operation of each switch.

The third and fourth switches S3 and S4 are connected in parallel between the inductor L1 and the capacitor C so as to pass current in both directions. Switching devices used in power switches include various devices such as an insulated gate bipolar transistor (IGBT), a MOS field effect transistor (MOST), a silicon controlled rectifier (SCR), or a gate turn off thyristor (GTO). For example, when the third and fourth switches S3 and S4 are configured to block voltage applied in both directions when off, such as IGBT, and pass current in one direction in the on state, both currents in both directions are allowed to pass. To do this, as shown in FIG. 40, the two switches may be connected in parallel in opposite directions.

On the other hand, when the third and fourth switches S3 and S4 are generally constituted by MOSFETs which are widely used in power switching circuits, the surface light source driving circuit according to the twelfth embodiment is configured as shown in FIG. The MOSFET contains a reverse conducting diode therein, which is shown in FIG. 41 as a diode connected in parallel with the switch in the third and fourth switches S3 and S4. When the reverse voltage is applied to the third and fourth switches S3 and S4 constituted by the MOSFET, the reverse conduction diode is turned on so that it cannot function as a switch. Therefore, in this case, the third and fourth switches S3 and S4 are connected to each of the third and fourth switches S3 and S4 by connecting the diodes d3 and d4 connected in series to the opposite directions of the reverse conducting diode. It can be configured to block bidirectional voltages.

The diode module including the first and second diodes d1 and d2 is connected to the first and second switches S1 and S2 in parallel to soft switch each switch. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx, and an anode electrode connected to ground. The first and second diodes d1 and d2 serve to pass forward current and block reverse current.

The capacitor C is connected between the third and fourth switches S3 and S4 and ground and is charged to a predetermined voltage. The capacitor C has a very large capacitance and operates as a direct current voltage source for supplying a voltage to the transformer Tx.

The operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 42 to 46 to be described later. Fig. 42 is a timing diagram showing the operation of the surface light source driving circuit according to the twelfth embodiment of the present invention. Referring to FIG. 42, the surface light source driving circuit according to the twelfth embodiment is driven while the four modes are periodically circulated according to on / off of the first to fourth switches S1 to S4.

43 to 46 are block diagrams showing equivalent circuits in each mode of the surface light source driving circuit according to the twelfth embodiment. The operation in each mode is as follows.

First, before mode 1 starts, the first, third and fourth switches S1, S3, S4 are off, and the second switch S2 remains in the on state so that no current flows on the circuit. At this time, the mode 1 starts while the third switch S3 is turned on. When the third switch S3 is turned on, the second switch S2 is turned off at the same time or with a slight time difference.

Mode 1: Referring to FIG. 43, Mode 1 in which the first, second and fourth switches S1, S2, S4 are turned off and the third switch S3 is turned on will be described. When the third switch S3 is turned on, the predetermined capacitor C voltage Vcc / 2 is applied to the inductor L, and the current i _L starts to increase. The current i _L emerges from the voltage source Vcc and is refluxed via the transformer Tx. When the voltage across the transformer Tx primary is equal to Vcc due to resonance between the inductor L and the capacitor component of the surface light source 10 and the parasitic capacitor on the circuit, the first diode d1 is turned on to obtain soft switching. do. When the first diode d1 is turned on, the current i _L flows into the input voltage source Vcc and the voltage of the ramp T1 is increased by the turns ratio at the primary voltage while the primary voltage of the transformer Tx is fixed at Vcc. (V _lamp ) is also fixed. When the primary side voltage of the transformer Tx does not reach Vcc, the first diode d1 is switched to mode 2 without conduction while the voltage is close to Vcc.

Mode 2: Referring to FIG. 44, Mode 2 in which the first switch S1 is in an on state and the second to fourth switches S2 to S4 are in an off state will be described. Soft switching is obtained by turning on the first switch S1 while the first diode d1 is turned on. Thereafter, the current i _Tx is output from the input voltage source Vcc through the first switch S1 and flows in the direction of the transformer Tx. In mode 2, light emission of the surface light source 10 occurs by the current i _Tx . The inductor current i _L is refluxed while the value stays near zero.

Mode 3: Referring to FIG. 45, Mode 3 in which the first to third switches S1 to S3 are turned off and the fourth switch S4 is turned on will be described. When the section in which the surface light source 10 emits light ends, the first switch S1 is turned off. As soon as the first switch S1 is turned off, since the current flowing into the surface light source 10 is cut off, the surface light source 10 is turned off, and a reverse voltage is applied to the inductor L, so that the current i _L is reversed. It starts to flow. The lamp voltage V _lamp rapidly decreases as the current i _L extracts the charge accumulated in the surface light source 10 through the transformer Tx.

When the lamp voltage V _lamp of the surface light source 10 reaches near zero, the second diode d2 is turned on to fix the lamp voltage V _lamp to zero, and the transformer Tx primary voltage is also zero. It is fixed. Soft switching is obtained by turning on the second switch S2 while the current i _L flows to the second diode d2. If the primary voltage of the transformer Tx does not reach 0, the second switch S2 is forcibly turned on to perform hard switching.

Mode 4: Mode 4, in which the equivalent circuit is shown in FIG. 46, has no idle current because the first, third and fourth switches S1, S3, S4 are off and the second switch S2 is on. to be. After Mode 4, Mode 1 is repeated.

The surface light source driving circuit according to the twelfth embodiment described above is characterized in that the light emission time (mode 2) and resonance time (mode 1, mode 3) of the surface light source can be easily adjusted.

Example 13

Fig. 47 is a timing diagram showing the operation of the surface light source driving circuit according to the thirteenth embodiment of the present invention. The surface light source driving circuit according to the thirteenth embodiment adds a current injection mode for soft switching to the surface light source driving circuit according to the twelfth embodiment. The configuration of the surface light source driving circuit according to the thirteenth embodiment is the same as that of the surface light source driving circuit according to the twelfth embodiment described above, except that only the operation of each switch is different.

Referring to FIG. 47, in the surface light source driving circuit according to the thirteenth embodiment, before the mode 1 starts, the second and third switches S2 and S3 are turned on and the first and fourth switches S1 and S4 are turned on. There is a mode 0 that is off, and a mode 2 'exists between the mode 2 and the mode 3, wherein the first and fourth switches S1 and S4 are on and the second and third switches S2 and S3 are off. . The surface light source driving circuit according to the thirteenth embodiment is driven while the six modes of mode 0 to mode 4 and mode 2 'are cyclically cycled. 48 and 49 are diagrams showing equivalent circuits in mode 0 and mode 2 'of the surface light source driving circuit according to the thirteenth embodiment, respectively.

Mode 0: Referring to FIG. 48, Mode 0 in which the second and third switches S2 and S3 are on and the first and fourth switches S1 and S4 are off will be described. When the second and third switches S2 and S3 are turned on, current flows back from the input voltage source Vcc through the third switch S3, the inductor L and the second switch S2. Accordingly, the input voltage Vcc is applied to the inductor L1 and the current i _L constantly rises. After the value of the current i _L flowing through the inductor L1 is uniformly formed, the second switch S2 is turned off, and mode 1 starts. Since the operation of the surface light source driving circuit according to the thirteenth embodiment in Mode 1 and Mode 2 is the same as the operation of the surface light source driving circuit according to the twelfth embodiment, detailed description thereof will be omitted.

After mode 2, mode 2 'is started in which the first and fourth switches S1 and S4 are on and the second and third switches S2 and S3 are off. Since the operation in the mode 2 'is the same as the operation in the mode 0 described above, only the direction of the current i _L is reversed, and thus a detailed description thereof is omitted. After the mode 2 ', the mode 3 starts with the first switch S1 turned off. Since the operation of the surface light source driving circuit according to the thirteenth embodiment in the mode 3 and the mode 4 is the same as the operation of the surface light source driving circuit according to the twelfth embodiment, detailed description thereof will be omitted.

In the surface light source driving circuit according to the thirteenth embodiment, the current of the inductor L is injected into the resonance in modes 0 and 2 ', thereby replenishing energy insufficient for soft switching. The twelfth and thirteenth embodiments are unidirectional drive circuits in which the lamp voltage has only one sign. A circuit in which the surface light source driving circuit according to the twelfth embodiment is modified to enable bidirectional driving is described in the fourteenth embodiment.

Example 14

50 is a configuration diagram showing a surface light source driving circuit according to a fourteenth embodiment of the present invention. Referring to FIG. 50, the surface light source driving circuit according to the fourteenth embodiment may include first and second inductors L1 and L2, first and second capacitors C1 and C2, a transformer Tx, and four diodes. (d1 to d4) and eight switches S1 to S8.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10.

The first switching module including the first to fourth switches S1 to S4 controls the input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. Is connected to. The four switches S1 to S4 periodically perform an on / off switching operation.

Diode modules composed of first to fourth diodes d1 to d4 are connected to the first to fourth switches S1 to S4 in parallel to soft switch each switch. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx and an anode electrode connected to ground. In the third diode d3, an anode electrode is connected to the other end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The fourth diode d4 has a cathode electrode connected to the other end of the primary winding of the transformer Tx, and an anode electrode connected to ground. Four diodes (d1 to d4) serve to pass forward current and block reverse current.

The first and second inductors L1 and L2 pass a current to the transformer Tx or a current output from the transformer Tx. The first inductor L1 is connected to one end of the primary winding of the transformer Tx, and the second inductor L2 is connected to the other end of the primary winding of the transformer Tx.

The second switching module composed of the fifth to eighth switches S5 to S8 is connected between each inductor and a capacitor to pass current in both directions according to the on / off operation of each switch. Fifth and sixth switches S5 and S6 are connected in parallel between the first inductor L1 and the first capacitor C1, and seventh and eighth switches S7 and S8 are connected to the second inductor. It is connected in parallel with each other between (L2) and the second capacitor (C2). The four switches S5 to S8 also periodically perform on / off switching operations.

As described above with respect to the twelfth embodiment, the fifth to eighth switches S5 to S8 may block bidirectional voltages when they are turned off, and are configured as an element such as an IGBT that passes a current in one direction when turned on. Can be. In this case, each of the fifth and sixth switches S5 and S6 and the seventh and eighth switches S7 and S8 are connected in parallel in opposite directions to pass both currents in both directions. As in the twelfth embodiment, when the fifth and eighth switches S5 to S8 are constituted of a device such as a MOSFET having a reverse conducting diode therein, the fifth and eighth switches ( Each of S5 to S8 requires fifth to eighth diodes d5 to d8 connected in series in a direction opposite to that of the reverse conducting diode, and the surface light source driving circuit according to the fourteenth embodiment configured as described above is illustrated in FIG. 51. Is shown.

The first and second capacitors C1 and C2 have very large capacitances and operate as direct current voltage sources supplying voltage to the transformer Tx. The first capacitor C1 is connected between the fifth and sixth switches S5 and S6 and the ground and charged to a preset voltage. In addition, the second capacitor C2 is connected between the seventh and eighth switches S7 and S8 and the ground and charged to a predetermined voltage.

An operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIG. 52 to be described later. Fig. 52 is a timing diagram showing the operation of the surface light source driving circuit according to the fourteenth embodiment of the present invention. Referring to FIG. 52, the surface light source driving circuit according to the fourteenth embodiment is driven while the eight modes of the modes 1 to 8 are periodically cycled according to the on / off of the first to eighth switches S1 to S8. do.

In the fourteenth embodiment, the operation of the surface light source driving circuit in each mode is the same as that of the twelfth embodiment described with reference to Figs. However, the left and right bridges of the full bridge circuit are switched 180 degrees with respect to the surface light source 10, so that the second, third, seventh and eighth switches S2, S3, S7, and S8 operate. The only difference is that the surface light source 10 lamp voltage V _lamp alternates between a positive value and a negative value. Therefore, since the operation of the surface light source driving circuit according to the fourteenth embodiment can be easily understood by those skilled in the art from the surface light source driving circuit according to the twelfth embodiment, a detailed description thereof will be omitted.

Example 15

Fig. 53 is a timing diagram showing the operation of the surface light source driving circuit according to the fifteenth embodiment of the present invention. The surface light source driving circuit according to the fifteenth embodiment adds a current injection mode for soft switching to the surface light source driving circuit according to the fourteenth embodiment. The configuration of the surface light source driving circuit according to the fifteenth embodiment is the same as that of the surface light source driving circuit according to the fourteenth embodiment described above, except that only the operation of each switch is different as shown in FIG.

Referring to FIG. 53, in the surface light source driving circuit according to the fifteenth embodiment, mode 0 in which the second, fourth, and fifth switches S2, S4, and S5 are on and the remaining switches are off before the mode 1 starts. Is present, and there is a mode 2 'between the first and fourth switches S1, S4, and S6 that are on and the other switches are off between modes 2 and 3. In addition, between the mode 4 and the mode 5, the second, fourth and seventh switch (S2, S4, S7) is on and the other switch is off mode 4 'is present, and between the mode 6 and mode 7 There is a mode 6 'in which the third and eighth switches S2, S3, S8 are on and the remaining switches are off. The surface light source driving circuit according to the fifteenth embodiment is driven while the 12 modes of modes 0 to 8, mode 2 ', mode 4' and mode 6 'are periodically cycled.

In the fifteenth embodiment, the operation of the surface light source driving circuit in each mode is the same as that of the thirteenth embodiment described with reference to FIGS. 47 to 49. However, the left and right bridges of the full bridge circuit are switched 180 degrees with respect to the surface light source 10, so that the second, third, seventh and eighth switches S2, S3, S7, and S8 operate. The only difference is that the _lamp voltage V _lamp of the surface light source 10 alternates between a positive value and a negative value. Therefore, since the operation of the surface light source driving circuit according to the fifteenth embodiment can be easily understood by those skilled in the art from the surface light source driving circuit according to the thirteenth embodiment, a detailed description thereof will be omitted.

Example 16

54 is a block diagram showing a surface light source driving circuit according to a sixteenth embodiment of the present invention. The surface light source driving circuit according to the sixteenth embodiment is a half bridge type surface light source driving circuit capable of bidirectional driving of the surface light source. Referring to FIG. 55, the surface light source driving circuit according to the sixteenth embodiment includes a capacitor C1, a transformer Tx, two diodes d1 and d2, and four switches S1 to S4.

The transformer Tx is coupled to both ends of the power supply terminal of the surface light source 10 to supply a driving voltage to the surface light source 10. That is, the voltage applied to both ends of the primary winding is induced at both ends of the secondary winding in proportion to the winding ratio of the transformer Tx and is applied as the driving voltage to the surface light source 10. The transformer Tx includes a magnetizing inductor L _M on the primary side.

The capacitor C1 is connected between the other end of the primary winding of the transformer Tx and ground and is charged with a predetermined voltage. The capacitor C1 has a very large capacitance and operates as a voltage source for supplying a voltage to the transformer Tx.

The switching module including the first to fourth switches S1 to S4 controls an input voltage applied to the transformer Tx so that a voltage in the form of a pulse is applied to the surface light source 10. The first switch S1 is connected between one end of the primary winding of the transformer Tx and the input voltage source Vcc, and the second switch S2 is connected between one end of the primary winding of the transformer Tx and ground. The third and fourth switches S3 and S4 are connected in parallel in opposite directions between one end and the other end of the primary winding of the transformer Tx. The four switches S1 to S4 periodically perform an on / off switching operation.

As described above in connection with the twelfth and fourteenth embodiments, the third and fourth switches S3 and S4 may block the bidirectional voltage when turned off and the IGBT which passes current in one direction when turned on. It may be composed of the same element. In this case, the third and fourth switches S3 and S4 are connected in parallel in opposite directions to pass both currents in both directions. As in the twelfth and fourteenth embodiments, when the third and fourth switches S3 and S4 are constituted of a device such as a MOSFET having a reverse conducting diode therein, the third and fourth switches S3 and S4 may be used to stop the bidirectional voltage. And fourth and fifth diodes d4 and d5 connected in series to opposite directions of the reverse conducting diode to each of the fourth switches S3 and S4, and the surface light source according to the sixteenth embodiment configured as described above. The drive circuit is shown in FIG.

The diode module composed of the first and second diodes d1 and d2 is connected to the first and second switches S1 and S2 in parallel to soft switch each switch. In the first diode d1, an anode electrode is connected to one end of the primary winding of the transformer Tx, and a cathode electrode is connected to the input voltage source Vcc. The second diode d2 has a cathode electrode connected to one end of the primary winding of the transformer Tx, and an anode electrode connected to ground. The two diodes d1 and d2 serve to pass forward current and block reverse current.

An operation of the surface light source driving circuit according to the embodiment of the present invention configured as described above will be described with reference to FIGS. 56 to 60. 56 is a timing diagram showing the operation of the surface light source driving circuit according to the sixteenth embodiment of the present invention. Referring to FIG. 56, the surface light source driving circuit according to the sixteenth embodiment is driven while the four modes are periodically cycled according to on / off of the first to fourth switches S1 to S4.

57 to 60 are block diagrams showing equivalent circuits in each mode of the surface light source driving circuit according to the sixteenth embodiment. The surface light source driving circuit according to the sixteenth embodiment implements an energy recovery function and a soft switching operation by using the magnetization inductor L _M. The operation in each mode is as follows.

Mode 1: Referring to FIG. 57, Mode 1 in which the first to third switches S1 to S3 are off and the fourth switch S4 is on will be described. In mode 1, current i _Lm is refluxed through fourth switch S4. At this time, when the fourth switch S4 is turned off, the inductor current i _Lm conducts the first diode d1 and turns on the first switch S1 simultaneously with or slightly later than the conduction of the first diode d1. Mode 2 starts.

Mode 2: Referring to FIG. 58, Mode 2 in which the second to fourth switches S2 to S4 are turned off and the first switch S1 is turned on will be described. Soft switching is obtained by turning on the first switch S1 while the first diode d1 is turned on. If the inductor current i _Lm is insufficient due to the conduction of the first diode d1, the first switch S1 is turned on without the conduction of the first diode d1 (hard switching). When the first switch S1 is turned on, a current may flow in the first switch S1, and a voltage Vcc / 2 is applied to the inductor L _M. The current i _Lm decreases as voltage is applied and then changes direction. Accordingly, the lamp voltage V _lamp also increases and then decreases, so that the surface light source 10 emits light in Mode 2. FIG.

Mode 3: Referring to Fig. 59, Mode 3 in which the first, second and fourth switches S1, S2, S4 are off and the third switch S3 is on will be described. When the section in which the surface light source 10 emits light ends, the first switch S1 is turned off. As soon as the first switch S1 is turned off, the current flowing into the surface light source 10 is cut off, so that the surface light source 10 is turned off, and the current is supplied from the input voltage source Vcc through the first switch S1. Therefore, the lamp voltage V _lamp is drastically reduced while the current i _Lm extracts the charge accumulated in the surface light source 10 through the transformer Tx. When the lamp voltage V _lamp of the surface light source 10 reaches near zero, since the third switch S3 is turned on, the current i _Lm is refluxed through the third switch S3.

Mode 4: Mode 4 in which the equivalent circuit is shown in FIG. 60 has no flow of current since the first, third and fourth switches S1, S3, S4 are off and the second switch S2 is on. It's a rest period. When the third switch S3 is turned off, the second diode d2 is turned on by the current i _{Lm which} is refluxed, and soft switching is obtained by turning on the second switch S2. If the inductor current i _Lm is insufficient due to the conduction of the second diode d2, the second switch S2 is turned on without the conduction of the second diode d2 (hard switching). The current flowing through the second switch S2 changes direction when the magnetizing inductor L _M receives the reverse voltage of Vcc / 2 output from the capacitor C, and the light emission of the surface light source 10 Happens. After Mode 4, Mode 1 is repeated.

This circuit not only uses the magnetizing inductor of the transformer as a current source, but also the transformer itself as an ideal boost element, so that the leakage inductance does not participate in the main operation. As a half-bridge type applied, the current stress of the switch and the turn ratio of the transformer can be configured differently from the full bridge.

Example 17

Fig. 61 is a block diagram showing the surface light source driving circuit according to the seventeenth embodiment of the present invention. Referring to FIG. 61, the surface light source driving circuit according to the seventeenth embodiment includes a second capacitor C2 added to the surface light source driving circuit according to the sixteenth embodiment described above with reference to FIGS. 54 through 60. to be.

The second capacitor C2 is connected between the other end of the primary winding of the transformer Tx and the input voltage source Vcc and is charged with a preset voltage. In driving the surface light source 10, the second capacitor C2 operates as a voltage source similarly to the first capacitor C1. The operation of the surface light source driving circuit according to the seventeenth embodiment is the same as the operation of the surface light source driving circuit according to the sixteenth embodiment described with reference to FIGS. 54 to 60, and thus can be easily understood by those skilled in the art. Will be omitted.

While specific embodiments of the present invention have been illustrated and described, the technical spirit of the present invention is not limited to the accompanying drawings and the above description, and various modifications can be made without departing from the spirit of the present invention. It will be apparent to those skilled in the art, and variations of this form will be regarded as belonging to the claims of the present invention without departing from the spirit of the present invention.

1 is a photograph showing a front discharge state according to glow discharge of a surface light source lamp.

2 is a graph illustrating a lamp voltage and a lamp current for driving a surface light source.

3 is a block diagram showing a surface light source driving circuit according to a first embodiment of the present invention.

4 is a timing diagram showing the operation of the surface light source driving circuit according to the first embodiment of the present invention.

5 is a configuration diagram showing an equivalent circuit in Mode 1 of the surface light source driving circuit according to the first embodiment of the present invention.

6 is a configuration diagram showing an equivalent circuit in mode 2 of the surface light source driving circuit according to the first embodiment of the present invention.

7 is a block diagram showing an equivalent circuit in mode 3 of the surface light source driving circuit according to the first embodiment of the present invention.

8 is a block diagram showing a surface light source driving circuit according to a second embodiment of the present invention.

9 is a block diagram showing a surface light source driving circuit according to a third embodiment of the present invention.

10 is a timing diagram showing the operation of the surface light source driving circuit according to the third embodiment of the present invention.

Fig. 11 is a block diagram showing an equivalent circuit in mode 0 of the surface light source driving circuit according to the third embodiment of the present invention.

12 is a block diagram showing a surface light source driving circuit according to a fourth embodiment of the present invention.

13 is a timing diagram showing the operation of the surface light source driving circuit according to the fourth embodiment of the present invention.

Fig. 14 is a block diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the fourth embodiment of the present invention.

FIG. 15 is a configuration diagram showing an equivalent circuit in mode 2 of the surface light source driving circuit according to the fourth embodiment of the present invention.

16 is a block diagram showing an equivalent circuit in mode 3 of the surface light source driving circuit according to the fourth embodiment of the present invention.

17 is a block diagram showing an equivalent circuit in mode 5 of the surface light source driving circuit according to the fourth embodiment of the present invention.

18 is a block diagram showing an equivalent circuit in mode 6 of the surface light source driving circuit according to the fourth embodiment of the present invention.

19 is a block diagram showing an equivalent circuit in mode 7 of the surface light source driving circuit according to the fourth embodiment of the present invention.

20 is a timing diagram showing the operation of the surface light source driving circuit according to the fifth embodiment of the present invention.

21 is a block diagram showing an equivalent circuit in mode 0 and mode 4 'of the surface light source driving circuit according to the fifth embodiment of the present invention.

22 is a block diagram showing a surface light source driving circuit according to a sixth embodiment of the present invention.

Fig. 23 is a timing diagram showing the operation of the surface light source driving circuit according to the sixth embodiment of the present invention.

24 is a configuration diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the sixth embodiment of the present invention.

Fig. 25 is a block diagram showing an equivalent circuit in mode 2 of the surface light source driving circuit according to the sixth embodiment of the present invention.

26 is a block diagram showing a surface light source driving circuit according to a seventh embodiment of the present invention.

27 is a block diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the seventh embodiment of the present invention.

28 is a block diagram showing a surface light source driving circuit according to an eighth embodiment of the present invention.

29 is a timing diagram showing the operation of the surface light source driving circuit according to the eighth embodiment of the present invention.

30 is a configuration diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the eighth embodiment of the present invention.

Fig. 31 is a block diagram showing an equivalent circuit in mode 2 of the surface light source driving circuit according to the eighth embodiment of the present invention.

32 is a block diagram showing an equivalent circuit in mode 3 of the surface light source driving circuit according to the eighth embodiment of the present invention.

Fig. 33 is a block diagram showing an equivalent circuit in mode 4 of the surface light source driving circuit according to the eighth embodiment of the present invention.

34 is a timing diagram showing the operation of the surface light source driving circuit according to the ninth embodiment of the present invention.

35 is a block diagram showing an equivalent circuit in mode 0 of the surface light source driving circuit according to the ninth embodiment of the present invention.

36 is a block diagram showing an equivalent circuit in mode 2 'of the surface light source driving circuit according to the ninth embodiment of the present invention.

37 is a block diagram showing a surface light source driving circuit according to a tenth embodiment of the present invention.

38 is a timing diagram showing the operation of the surface light source driving circuit according to the tenth embodiment of the present invention.

39 is a timing diagram showing the operation of the surface light source driving circuit according to the eleventh embodiment of the present invention.

40 is a block diagram showing a surface light source driving circuit according to a twelfth embodiment of the present invention.

41 is still another configuration diagram showing the surface light source driving circuit according to the twelfth embodiment of the present invention.

42 is a timing diagram showing the operation of the surface light source driving circuit according to the twelfth embodiment of the present invention.

Fig. 43 is a block diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the twelfth embodiment of the present invention.

Fig. 44 is a block diagram showing an equivalent circuit in mode 2 of the surface light source driving circuit according to the twelfth embodiment of the present invention.

45 is a configuration diagram showing an equivalent circuit in mode 3 of the surface light source driving circuit according to the twelfth embodiment of the present invention.

Fig. 46 is a block diagram showing an equivalent circuit in mode 4 of the surface light source driving circuit according to the twelfth embodiment of the present invention.

Fig. 47 is a timing diagram showing the operation of the surface light source driving circuit according to the thirteenth embodiment of the present invention.

48 is a block diagram showing an equivalent circuit in mode 0 of the surface light source driving circuit according to the thirteenth embodiment of the present invention.

Fig. 49 is a block diagram showing an equivalent circuit in mode 2 'of the surface light source driving circuit according to the thirteenth embodiment of the present invention.

50 is a configuration diagram showing a surface light source driving circuit according to a fourteenth embodiment of the present invention.

FIG. 51 is still another configuration diagram showing the surface light source driving circuit according to the fourteenth embodiment of the present invention.

52 is a timing diagram showing the operation of the surface light source driving circuit according to the fourteenth embodiment of the present invention.

Fig. 53 is a timing diagram showing the operation of the surface light source driving circuit according to the fifteenth embodiment of the present invention.

54 is a block diagram showing a surface light source driving circuit according to a sixteenth embodiment of the present invention.

55 is still another configuration diagram showing the surface light source driving circuit according to the sixteenth embodiment of the present invention.

56 is a timing diagram showing the operation of the surface light source driving circuit according to the sixteenth embodiment of the present invention.

Fig. 57 is a block diagram showing an equivalent circuit in mode 1 of the surface light source driving circuit according to the sixteenth embodiment of the present invention.

58 is a configuration diagram showing an equivalent circuit in Mode 2 of the surface light source driving circuit according to the sixteenth embodiment of the present invention.

Fig. 59 is a block diagram showing an equivalent circuit in mode 3 of the surface light source driving circuit according to the sixteenth embodiment of the present invention.

60 is a configuration diagram showing an equivalent circuit in mode 4 of the surface light source driving circuit according to the sixteenth embodiment of the present invention.

Fig. 61 is a block diagram showing the surface light source driving circuit according to the seventeenth embodiment of the present invention.

Claims (5)

A transformer having a primary winding and a magnetizing inductor connected to each other on a primary side, the secondary winding being coupled to both ends of a power terminal of the surface light source to supply a driving voltage to the surface light source; A switching module connected to the primary winding of the transformer and the magnetizing inductor, and converting a voltage output from an input voltage source into a pulse to apply the voltage to the transformer; And And a diode module connected to the switching module for soft switching and power recovery driving. The method of claim 1, The diode module, A first diode having an anode electrode connected to one end of the primary winding of the transformer and a cathode electrode connected to an input voltage source; A second diode having a cathode electrode connected to one end of the primary winding of the transformer and an anode electrode connected to ground; A third diode having an anode electrode connected to the other end of the primary winding of the transformer and a cathode electrode connected to an input voltage source; And And a fourth diode having a cathode electrode connected to the other end of the primary winding of the transformer and an anode electrode connected to ground. The method of claim 1, The switching module, A first switch connected between one end of the primary winding of the transformer and an input voltage source; A second switch connected between one end of the primary winding of the transformer and ground; A third switch connected between the other end of the primary winding of the transformer and an input voltage source; And And a fourth switch connected between the other end of the primary winding of the transformer and the ground. The method of claim 3, wherein The switching module, Four modes are sequentially operated according to the on / off of the first to fourth switches. The four modes, Mode 1, wherein the second and third switches are off and the first and fourth switches are on; Mode 2, wherein the first and third switches are off and the second and fourth switches are on; Mode 3, wherein the first and fourth switches are off and the second and third switches are on; And a mode 4 in which the first and third switches are off and the second and fourth switches are on. The method of claim 1, And a reset circuit connected to the primary winding of the transformer to prevent the transformer from being saturated.

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