HK1069005B - High-voltage transformer and discharge lamp driving apparatus - Google Patents

Description

High-voltage transformer and discharge lamp driving device

RELATED APPLICATIONS

This application claims priority from japanese patent application No.2003-12248, filed on 25/4/2003, which is incorporated by reference into this application.

Technical Field

The present invention relates to a high-voltage transformer and a discharge lamp driving device used in a discharge lamp lighting circuit used for a backlight in a liquid crystal display panel, for example, and particularly relates to a high-voltage transformer and a discharge lamp driving device used in a DC/AC inverter circuit that simultaneously lights many discharge lamps.

Background

For example, it is generally known to use many of them simultaneously as a PC in a notebook_sCold cathode fluorescent lamp (hereinafter referred to as CCFL) for backlighting various liquid crystal display panels used in the same_s) Discharge/glow. Using many CCFLs like this_sCan be adapted to the need for high brightness and the need for uniform illumination in liquid crystal display panels.

A typical circuit for lighting such a CCFL is known as an inverter circuit which converts a voltage of about 12VDC to a high frequency voltage of about 2000V or up to 60kHz by using a high voltage transformer so as to start discharging. After the discharge is initiated, the inverter circuit adjusts the high frequency voltage down to a voltage of about 800V, which is required to maintain the CCFL discharge.

As high-voltage transformers (inverter transformers) used in an inverter circuit such as this, those of small size have been used in view of the demand for making the liquid crystal display panel thinner. Since many CCFLs are required in a single liquid crystal display_sThe number of high voltage transformers, and therefore there is a pressing need to create a technical solution that further saves space and manufacturing costs. A discharge lamp driving circuit shown in fig. 12 is known as an example adapted to such a demand.

Such a discharge lamp driving circuit is configured to supply a DC input voltage to the primary side of the high-voltage transformer 610 through a known Royer oscillation circuit so that a high voltage of about 2000V or more is generated on the secondary side of the high-voltage transformer 610 at the time of starting lighting of the discharge lamp, while the high voltage on the secondary side is applied to the cold cathode fluorescent lamps CCFL1, CCFL2 through the ballast capacitors Cb1, Cb2, respectively. The ballast capacitors Cb1, Cb2 connected in series with the CCFLs 1, 2, respectively, can eliminate fluctuations in starter voltage of the respective lamps, and thus can light up many CCFLs by a single dimmer while suppressing fluctuations in discharge operation of the respective CCFLs_s。

However, a voltage 2 to 2.5 times (1600 to 2000V between both ends of the CCFL) of the normal lighting (800V between both ends) is required when the CCFL starts to emit light and a voltage of about 400V or more is separately applied between both ends of the ballast capacitor Cb connected to the CCFL, and thus a high voltage of at least about 2000V is output from the transformer secondary side when the CCFL starts to emit light and maintains the normal lighting.

Continuously outputting such a high voltage lowers the reliability of the transformer, and thus it is difficult to ensure safety against the insulation voltage between the transformer and the secondary coil in the like.

The secondary voltage may be changed at the time when the CCFL starts to emit light and at the time of normal light emission so as to be lowered at the time of normal light emission. However, the high voltage transformer 610 does not have a function of adjusting its voltage. Even though the circuit part for driving the high voltage transformer 610 as a whole has the PWM control function, this is generally a voltage control function for keeping the lamp lighted at the time of normal lighting, and thus it is substantially difficult to convert the starter voltage of about 2000V or more to the normal lighting voltage of about 800V.

Therefore, when applying a technique of converting the secondary voltage between the initial light-emitting time and the normal light-emitting time, it is required that the structure to be improved is substantially different from the conventional structure.

Disclosure of Invention

An object of the present invention is to provide a secondary voltage-switchable high voltage transformer and a discharge lamp driving apparatus capable of stably lighting a plurality of discharge lamps with a single transformer, improving the reliability of the transformer, and ensuring safety against an insulation voltage between secondary coils such as the transformer.

In order to achieve the above object, the present invention provides a high voltage transformer for lighting a plurality of discharge lamps, the high voltage transformer including a primary coil to which an AC voltage is input and a secondary coil outputting a predetermined AC voltage higher than the input AC voltage.

Wherein the primary coil includes a starter primary winding for initially lighting the discharge lamp and a normal lighting winding for normally lighting the discharge lamp.

The starter primary winding may be formed by a portion of the normally luminous primary winding by providing a center tap in the normally luminous primary winding, or may be formed separately from the normally luminous primary winding so as to have a smaller diameter than that of the normally luminous primary winding.

Most preferably, the starter primary winding has fewer turns than the normally lit primary winding.

The high voltage transformer may be an inverter transformer.

The discharge lamp may be a cold cathode fluorescent lamp.

The present invention provides a discharge lamp driving apparatus including the high voltage transformer of the present invention, the apparatus further comprising:

the first switching converter is used for controlling the electrifying state of the primary winding of the starter; and

and a second switching converter for controlling the energization state of the normal light emitting primary winding.

Most desirably, the switching frequency for driving the first switching converter and the switching frequency for driving the second switching converter are switchable therebetween.

Most desirably, the first and/or second switching converter is a full bridge circuit.

Most preferably, the first and second switching converters are partially shared.

Most preferably, the first switching converter energizes the starter primary winding for a predetermined time, and then the second switching converter energizes the normally lit primary winding.

Drawings

FIG. 1 is a general plan view of a high voltage transformer according to an embodiment of the present invention;

fig. 2 is a wiring diagram of a high voltage transformer according to the above embodiment;

fig. 3 is a circuit diagram showing a discharge lamp (apparatus) according to an embodiment of the present invention;

FIG. 4 is a block diagram illustrating the lighting controller shown in FIG. 3;

fig. 5A and 5B are flowcharts showing a CPU processing routine of the oscillation frequency controller shown in fig. 4;

FIG. 6 is an external view showing a modified mode of the transformer wiring diagram of FIG. 2;

fig. 7 is a sectional view showing an example of application of the present invention to a high voltage transformer of a so-called double transformer type;

fig. 8 is a circuit diagram showing a modified mode of the discharge lamp driving circuit of fig. 3;

fig. 9 is a circuit diagram showing a modified mode of the discharge lamp driving circuit of fig. 3;

fig. 10 is a schematic plan view showing a modified mode of the high voltage transformer shown in fig. 1;

fig. 11 is a transformer wiring diagram showing a high voltage transformer according to the prior art; and

fig. 12 is a circuit diagram showing a discharge lamp driving circuit according to the prior art.

Description of the preferred embodiments

Hereinafter, a high voltage transformer according to one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Fig. 1 is a plan view showing an external appearance of a high voltage transformer according to an embodiment of the present invention, and fig. 2 is a wiring diagram showing a principle of characteristics of the high voltage transformer.

The high voltage transformer 11 according to this embodiment shown in FIG. 1 is a two CCFL_sAn inverter transformer used in a DC/AC inverter circuit for simultaneous discharge/light emission (cold cathode fluorescent lamp). Its primary coil 45 and secondary coil 47 are wound around a common strip core (not visible in fig. 1) made of ferrite or such a soft magnetic material and are mutually electromagnetically connected by the common strip core.

The insulating portion 44 is disposed between the primary coil 45 and the secondary coil 47.

In practice, the primary coil 45 and the secondary coil 47 are wound around the outer periphery of the hollow bobbin 21 having a rectangular cross section, and the bar-shaped magnetic core is inserted into the bobbin 21. Both end faces of the winding frame 21 are provided with caps 41a, 41 b.

The strip-shaped magnetic core is electromagnetically connected to a frame-shaped magnetic core 29 made of the same material as the strip-shaped magnetic core, thereby forming a magnetic path.

At this time, the gap amount between the strip-shaped core and the frame-shaped core 29 is determined from the amount of leakage magnetic flux to be generated; and the amount of gap between the strip-shaped magnetic core and the frame-shaped magnetic core 29 can be made zero. Further, in the case where the frame-shaped magnetic core 29 is not provided, the magnetic core can be constituted by using only the strip-shaped magnetic core, so that the open magnetic path structure is formed.

The front end, the intermediate terminal 45T and the terminal of the primary coil 45 are connected to terminal leads 17a, 17b, 17d fixed to the terminal holder 27 of the coil, respectively. The front end and the terminals of the secondary coil 47 are connected to terminal leads 18a, 18b, respectively, which are fixed to a terminal support 28 of the coil. The terminal brackets 27, 28 are made of an insulating material.

As shown in fig. 2, the high-voltage transformer 11 is wired, both ends of the primary coil 45 are connected to the terminal leads 17a, 17b, and the intermediate terminal 45T is connected to the terminal lead 17 d. On the other hand, the secondary coil 47 is connected to the terminal leads 18a, 18 b. The winding between one end of the primary coil 45 and the intermediate terminal 45T forms a starter winding, while the winding between the ends of the primary coil 45 forms a normally luminous primary winding. This forms two kinds of primary coils contained in the common portion, each having a different number of turns from each other.

As described above, fig. 2 shows the characteristics of the high-voltage transformer 11 according to the present embodiment, which are more clearly seen when compared with fig. 11 showing the wiring state of the conventional high-voltage transformer in which both ends of the primary coil 145 are connected to the terminal leads 117a, 117b, respectively, and both ends of the secondary coil 147 are connected to the terminal leads 118a, 118b, respectively.

Fig. 3 shows a discharge lamp driving circuit equipped with a high-voltage transformer 64 according to the present embodiment.

In the above discharge lamp driving circuitDriving two CCFLs connected to the secondary side of a high voltage transformer 64_s(CCFL1, CCFL2) emits light, and the full bridge circuit 60 and the light emission controller 63 connected on the primary side of the high voltage transformer 64 constitute an inverter circuit.

As shown in fig. 3, a full bridge circuit 60 having a voltage supplied from a DC power supply line (Vcc) generates an AC voltage. The high voltage transformer 64 boosts the AC voltage delivered to the primary coil 64A, thereby enabling the secondary coil 64B to generate an AC high voltage. The generated AC high voltage is then applied to the two CCFLs connected at the secondary coil 64B_s(CCFL1, CCFL 2). In order to make two CCFLs to which AC high voltage is applied_sSecondary coil 64B in high voltage transformer 64 and corresponding CCFL capable of emitting light stably at the same time_sBallast capacitors (Cb1, Cb2) are connected between the CCFLs 1, 2.

In the present embodiment, as explained in relation to fig. 2, the winding between one of the ends (a or c) of the primary coil 64A and the intermediate terminal (b) constitutes the starter primary winding (with a smaller number of turns), and the winding between the ends (a and c) of the primary coil 64A constitutes the normal light emitting primary winding (with a larger number of turns).

In this embodiment, two primary windings are configured for the following reasons:

at the time when the CCFL starts to emit light, a voltage 2 to 2.5 times that at the time of normal light emission is required, and thus a high voltage of about 1600 to 2000V is generally applied between both ends of the CCFL. Therefore, the insulation breakdown voltage between the turns on the secondary winding or the like in use is close to its limit.

In order to allow a single high voltage transformer 64 to stably illuminate multiple CCFLs simultaneously_sThe ballast capacitor Cb is connected to its corresponding CCFL, so that, for example, a voltage of 400V is applied separately to both ends of the ballast capacitor Cb. Therefore, some CCFLs do not start to emit light if the voltage reached by adding, for example, 400V to the above-mentioned voltage of about 1600 to 2000V is not formed on the secondary side 64B.

When the above-mentioned high voltage is continuously generated, it is difficult to secure the safety against the insulation voltage between the secondary coils in the transformer. In addition, the reliability of the transformer is reduced.

Therefore, when the discharge lamp starts to emit light, the starter primary winding (a-B) having a small number of turns (e.g., 10 turns) is used as shown in fig. 2 and 3 in order to obtain a high boosting ratio, thereby enabling the secondary winding 64B to generate a high voltage (e.g., 2000V) required for the discharge lamp to start to emit light. In CCFL_sAfter starting the lighting, instead, the normally lit primary winding (a-c) is used with a larger number of turns (e.g., 18 turns), thus enabling the secondary winding 64B to generate the low voltage (e.g., 1200V) required to maintain the lighting of the discharge lamp.

The full bridge circuit 60 includes a first stage transfer switch section a, a second stage transfer switch section B, and a third stage transfer switch section C, each of which includes two FETs. The starter primary windings (a-B) are energized when the first-stage changeover switch section a and the third-stage changeover switch section C are caused to change over therebetween, and the normally light-emitting primary windings (a-C) are energized when the first-stage changeover switch section a and the second-stage changeover switch section B are caused to change over therebetween.

In other words, the starter primary winding (a-b) is energized while the first state in which the FETs 61A and 62C are turned on and the second state in which the FETs 62A and 61C are turned on are alternately repeated. In fig. 3, a solid line indicates a current path in the first state.

On the other hand, an AC voltage is applied to the normal light emitting primary winding (a-c) while a first state in which the FETs 61A and 62B are turned on and a second state in which the FETs 62A and 61B are turned on are alternately repeated. In fig. 3, the broken line indicates a current path in the first state.

The switching operation of the FETs 61A to 61C and 62A to 62C is controlled by the light emission controller 63. The structure of the light emission controller 63 will be described later.

The specific voltage values that occur in the secondary coil when the predetermined voltage is applied to the starter primary winding (a-b) and the normal light emitting primary winding (a-c) will now be calculated.

In this embodiment, the number of turns of the starter primary winding (a-b) is made smaller than that of the normal light emitting primary winding (a-c), as described above. In the above described example, the number of turns in the primary winding (a-b) of the starter to be used in the following calculations is 10, while the number of turns in the normal lighting primary winding (a-c) is 18.

Let the number of turns Ns of the secondary coil 64B be 1800 and the input voltage Vin on the primary side be 12V.

(1) Output voltage Vout of secondary coil in case of energizing starter primary winding (a-b):

Vout＝Vin×1.1×Ns/Np＝12V×1.1×1800/10＝2376V

(2) output voltage Vout of secondary coil in case of energizing normal light emitting primary winding (a-c):

Vout＝Vin×1.1×Ns/Np＝12V×1.1×1800/18＝1320V

in this case, assuming that each ballast capacitor Cb has a capacitance of 66PF, the voltage Vcb between both ends of the capacitance is 792V when the discharge lamp starts to emit light and 440V when the discharge lamp normally emits light. Therefore, in CCFL_sVoltage V between the two electrodes_L1584V when the discharge lamp starts emitting light and 880V when the discharge lamp normally emits light.

Therefore, in the above specific example, the high voltage of 2376V is generated from the secondary coil 64B at the time of starting lighting of the discharge lamp, and the voltage generated from the secondary coil 64B is decreased to 1320V at the time of normal lighting after the discharge lamp starts lighting. This prevents the secondary winding 64B of the high-voltage transformer 64 from continuously outputting a high voltage of about 2000V or more, thereby improving the reliability of the transformer and the safety against the insulation voltage between the transformer and the like secondary winding.

Even if the voltage is divided between both ends of each ballast capacitor Cb at a predetermined ratio, the above specific example can secure the voltage V between both electrodes of the CCFL at the time of starting lighting of the discharge lamp_LIs 1584V andvoltage V between two electrodes of CCFL during normal lighting of discharge lamp_LIs 800V, and thus can contribute to the operation of initially igniting and normally lighting the discharge lamp.

Fig. 4 is a block diagram showing the structure of the light emission controller 63. The lighting controller 63 regulates the switching of the full bridge circuit 60 with PWM control. In the full bridge circuit 60 in fig. 4, for convenience, the switching conversion portion related to initially lighting the discharge lamp is referred to as a first switching converter 60A and the switching conversion portion related to normally lighting the discharge lamp is referred to as a second switching converter 60B.

The light emission controller 63 includes an oscillation frequency controller 36 that outputs a square wave at a predetermined frequency; a triangular wave oscillator 34 for converting the square of the oscillation frequency controller 36 into a triangular wave; and a comparator 35 for comparing the error level signal for the error amplifier 32 with the triangular wave signal output from the triangular wave oscillator 34 and outputting the PWM control signal reaching the H level during a larger period of the triangular wave signal to a switching controller 37 through a switch 33. During the H-level period of the input PWM control signal, the switching controller 37 adjusts two driving devices 38A, 38B in the driving section 38 to selectively turn on one of the driving devices. When the first driving device 38A is turned on, the first switching converter 60A is driven so as to perform a conversion operation for initially lighting the discharge lamp. When the second driving device 38B is turned on, the second switching converter 60B is driven so as to perform a conversion operation of normally lighting the discharge lamp.

As shown in fig. 3, two CCFLs are used_sThe respective voltages on the ground side of (a) and the reference signal are supplied together as a feedback signal (FB signal) to the error amplifier 32. Since two resistors 66A, 66B are associated with the CCFL on the ground side_sConnected, the feedback signal thus corresponds to the respective voltage value of the resistors 66A, 66B between their ends.

When flowing through any CCFL_sIs decreased, so that the error level signal supplied from the error amplifier 32 to the comparator 35 is electrically equivalentThe level becomes low, so that the H level period of the PWM control signal input to the switching controller 37 becomes long. This lengthens the drive period of each switching converter 60A, 60B, thereby enabling a larger current to flow through the CCFL_s。

The light emission controller 63 further includes an abnormal voltage detector/comparator 31. As shown in fig. 3, the voltage value between the two capacitors 65A, 65B connected to the secondary side of the high voltage transformer 64 is supplied to the abnormal voltage detector/comparator 31 together with the reference voltage. When two CCFLs are damaged, an abnormal high voltage generally occurs on the secondary side of the high voltage transformer 64, thereby generating a concern that the high voltage transformer 64 may be damaged. Therefore, if it is determined that the abnormal voltage detector/comparator 31 detects an abnormally high voltage, a switch open signal is issued from the abnormal voltage detector/comparator 31 to immediately turn off the switch 33, so that the switching controller 37 stops driving the switching converters 60A, 60B, thereby interrupting the voltage supplied to the high voltage transformer 64. This prevents the high voltage transformer 64 from being damaged.

Fig. 5A is a flowchart showing a processing program of a CPU (not shown) for controlling the oscillation frequency controller 36, and a dedicated program thereof is stored in a ROM mounted to the CPU.

Referring to fig. 5A, whether the discharge lamp (CCFL) switch is conductive or non-conductive is determined throughout (S1). If it is determined that the on state is reached, the oscillation frequency controller 36 is enabled to output an oscillation frequency signal at an oscillation frequency for initially lighting the discharge lamp (S2), and a starter switch switching signal is supplied to the first driving device 38A (S3). Thereafter, it is determined whether a predetermined period of time (e.g., 2 to 3 seconds) has elapsed or not elapsed from the time when the discharge lamp starts to emit light (the time when the oscillation frequency signal is output) (S4). If it is determined that the predetermined time period has elapsed, the oscillation frequency controller 36 is enabled to output the oscillation frequency signal at the oscillation frequency for normally lighting the discharge lamp (S5), and the switching changeover signal for normally lighting the discharge lamp is supplied to the second driving device 38B (S6).

Thus, in the present embodiment, the switching frequency for a predetermined period from the time when the CCFL starts to emit light (from the time when the oscillation frequency signal is output) is adjusted high so as to contribute to resonance with the ballast capacitor Cb, and thus the light emission of the CCFL can be improved.

At a higher oscillation frequency, the conversion frequency of the first switching converter 60A is raised, and thus the core loss such as the core loss and the eddy current in the core portion of the high-voltage transformer 64 are increased, which may decrease the conversion efficiency of the transformer 64, or the switching loss caused by the first switching converter 60A is increased, which may increase the heat generation amount. Although as described above, since the period in which the frequency is high is short, the above-described core loss and switching loss are negligible.

The frequency of the oscillation frequency signal from the oscillation frequency control 36 can be stabilized. Fig. 5B is a flowchart showing a processing procedure of a CPU (not shown) that controls the oscillation frequency controller 36 in this case. In this routine, it is determined whether the discharge lamp is turned on or not turned on all the time (S11). If it is determined that the on state is reached, the starter transition signal is delivered to the first driving device 38A (S12). Thereafter, it is determined whether a predetermined period from the time when the discharge lamp starts to emit light (the time when the switching signal is output) or not has elapsed (S13). If it is determined that the predetermined time period has elapsed, the normal light emission switching signal is supplied to the second driving device 38B (S14).

The high-voltage transformer and the discharge lamp driving device according to the present invention are not limited to the above-described embodiments, and can be modified in various ways.

Fig. 6 shows a modification of the transformer wiring diagram of fig. 2. In this mode, the normal light emitting primary coil 45A and the starter primary coil 45B are formed independently of each other. Both ends of the normal light emitting primary coil 45A are connected to the terminal leads 17a, 17B, respectively, and both ends of the starter primary coil 45B are connected to the terminal leads 17c, 17d, respectively. In this case, for example, the number of turns in the starter primary coil 45B is 10 and the number of turns in the normal lighting primary coil 45A is 18.

Fig. 7 is a sectional view showing an example in which the present invention is applied to a so-called double-transformer type high-voltage transformer 11. It is clear that in this mode the starter primary coil 45B and the normally lit primary coil 45A are also formed independently of each other.

As shown in fig. 7, the center core 129A is electromagnetically connected to the frame-shaped core 129B, thereby forming a magnetic path.

Fig. 8 and 9 show a modified mode of the discharge lamp driving circuit of fig. 3. In fig. 8, elements corresponding to those in fig. 3 are denoted by numerals of fig. 3 plus 100. In fig. 9, elements corresponding to those in fig. 3 are denoted by numerals of fig. 3 plus 200. These elements will not be described in detail.

The discharge lamp driving circuit shown in fig. 8 is different from the discharge lamp driving circuit of fig. 3 in that the third stage changeover switch portion of the full bridge circuit 160 thereof includes a single FET 162C, and the starter primary coil 164D and the normal light emitting primary coil 164C thereof are formed independently of each other. In other words, in the discharge lamp driving circuit shown in fig. 8, the switching for initially lighting the discharge lamp is completed by the FET 162C on/off operation in the third stage changeover switch portion alone.

Therefore, the discharge lamp driving circuit shown in fig. 8 is simpler in circuit configuration and switching control as compared with the discharge lamp driving circuit shown in fig. 3, and can reduce the manufacturing cost since the number of FETs is reduced by 1.

The discharge lamp driving circuit shown in fig. 9 uses two FETs 261, 262 instead of the full bridge circuit in order to adjust the input voltage of its primary coil 264A. In other words, turning on or off the FET262 energizes the starter primary windings (a-b), while turning on or off the FET261, which is loaded with the power supply line (Vcc), energizes the normally illuminated primary windings (a-c).

Therefore, the discharge lamp driving circuit shown in fig. 9 is simpler in circuit configuration and switching control, and greatly reduces the manufacturing cost due to the smaller number of FETs, as compared with the discharge lamp driving circuit shown in fig. 3.

Fig. 10 shows a modification of the high-voltage transformer shown in fig. 1. The high-voltage transformer shown in fig. 10 is a high-voltage transformer in which a pair of so-called E-shaped magnetic cores 29A and 29B are opposed to each other to form a core portion. Further, in order to ensure a good insulation state, the secondary coil 47 is provided with insulation caps at a predetermined pitch.

The high-voltage transformer and the discharge lamp driving circuit of the present invention are not limited to the above-described embodiments, and the potentials can be applied to various types of transformers (both types of single transformer and double transformer including a wound primary coil arranged at the outer periphery of a wound secondary coil) such as, for example, transformers disclosed in japanese unexamined patent publication No. 2002-.

Although the above embodiments illustrate examples in which two CCFLs are illuminated by a single transformer, three or more CCFLs may be illuminated by a single transformer.

The high-voltage transformer of the invention can be applied not only to phase-reversal transformers but also to various transformers.

Although, as mentioned above, ferrite is preferred for the core, materials such as permalloy, sendust and carbonyl iron may also be used. It is also possible to use a dust core compacted from a fine powder of these materials.

As described above, while the high voltage is generated from the secondary winding at the time of starting the lighting of the discharge lamp, the high voltage transformer of the present invention switches the primary winding to which the voltage is applied from the starter winding to the normal lighting winding at the normal lighting timing after the starting of the lighting of the discharge lamp, so that the secondary voltage is reduced to a level sufficient for the discharge lamp to maintain the lighting. This enables the secondary winding of the high-voltage transformer to avoid continuing to output the high voltage for initial lighting of the discharge lamp.

Although the secondary is separately applied between both ends of each ballast capacitor at a predetermined ratio, a voltage between both electrodes of each discharge lamp at the time of starting lighting of the discharge lamp and a voltage between both electrodes of each discharge lamp at the time of normal lighting of the discharge lamp can be secured, and thus an operation of initially starting and normally lighting the discharge lamp can be smoothly performed.

Claims (11)

1. A high voltage transformer for lighting a plurality of discharge lamps, said high voltage transformer comprising a primary coil for inputting an AC voltage and a secondary coil for outputting a predetermined voltage higher than said input AC voltage,

wherein the primary coil includes a starter primary winding for initially lighting the discharge lamp and a normal lighting primary winding for normally lighting the discharge lamp.

2. The high voltage transformer of claim 1, wherein said starter primary winding is formed with a portion of said normally illuminated primary winding by providing a tap in said normally illuminated primary winding.

3. The high voltage transformer of claim 1, wherein said starter primary winding is independently disposed from said normally emitting primary winding and has a diameter smaller than that of said normally emitting primary winding.

4. The high voltage transformer of claim 1 wherein said starter primary winding has fewer turns than said normally emitting primary winding.

5. The high voltage transformer of claim 1, wherein said high voltage transformer is an inverter transformer.

6. The high voltage transformer of claim 1, wherein said discharge lamp is a cold cathode fluorescent lamp.

7. A discharge lamp driving apparatus comprising a high voltage transformer according to claim 1, said apparatus further comprising:

the first switch converter is used for controlling the electrifying state of the primary winding of the starter; and

and a second switching converter for controlling the energization state of the normal light emitting primary winding.

8. Discharge lamp driving apparatus according to claim 7, wherein a switching frequency for driving said first switching converter and a switching frequency for driving said second switching converter are switchable therebetween.

9. The discharge lamp driving apparatus according to claim 7, wherein said first and/or second switching converter is a full bridge circuit.

10. The discharge lamp driving apparatus according to claim 7, wherein said first and second switching converters are partially shared.

11. The discharge lamp driving device according to claim 7, wherein said first switching converter energizes said starter primary winding for a predetermined time, and then said second switching converter energizes said normal light emitting primary winding.