JPH02256191A - El luminous power circuit - Google Patents

Abstract

PURPOSE:To obtain an EL luminous power circuit with no energy loss and high energy efficiency by providing an inductor between an inverter and an EL. CONSTITUTION:An inverter having a pair of switches Tr1 and Tr2 is connected to +E and -E DC power sources in a power circuit, and switches Tr1 and Tr2 are opened or closed in turn with the switching frequency (f). A power transistor with the withstanding voltage of 2E or above is used for the switches Tr1 and Tr2. An EL (bipolar capacitor) as capacitance and a coil L as an inductor are connected in series and grounded in the inverter having the switches Tr1 and Tr2. When the phase between the load voltage and the load current is staggered, the switching energy loss by the power transistor is dissolved. A power circuit with high energy efficiency is obtained.

Description

[Detailed description of the invention] <Industrial application field> The present invention relates to an EL light emitting power supply circuit.

<Prior Art> EL is widely used as a backlight for EL displays and liquid crystal displays.

When the EL is used as a load, the EL is mainly a capacitance load and is usually used as an AC load. The emission brightness and the corresponding surface illuminance are EL
It is highly dependent on both the voltage and the AC frequency applied to the AC.

In order to make the EL emit brighter light, it is possible to increase the effective load voltage, increase the load frequency, or use a combination of both.

Therefore, a normal AC power supply (e.g. effective value 100V, 50V
If you want to emit light directly from an EL at a frequency of 60 Hz, you don't need much effort, but if you want to emit brighter light, you need to increase the frequency and the voltage within the withstand voltage range of the EL. When a normal 100VAC power supply, which requires
The absolute value peak of the maximum voltage applied to L is 140V (280V peak-to-peak), but the rated withstand voltage of normal EL is approximately 210V (480V peak-to-peak).
20V). Further, from the lifetime of EL, the practical upper limit of the frequency used is around 400 Hz.

Now, to explain the case of increasing the load frequency of EL, AC power is once rectified to become a DC power supply of about ±140V, and then, for example, a push-pull circuit is used to alternately connect positive and negative power supply circuits at the desired frequency f. It is normal to use an EL alternating current load with a frequency of f.

In this case, a power transistor, power MOSFET, or the like is usually used as a switch in the push-pull circuit.

<Problem to be solved by the invention> However, in such cases, power transistors and power M
Switching energy loss of OS FETs becomes a big problem, and it becomes necessary to use a relatively large heat sink, which results in large energy loss, and consideration must also be given to the location and method of installation.

A main object of the present invention is to provide an EL light emitting power supply circuit that eliminates energy loss and improves energy efficiency.

<Means for Solving the Problems> Such objects are achieved by the following inventions (1) to (9).

(1) In an EL light emitting power supply circuit that has a DC power supply and an inverter circuit and applies a voltage load to the EL or EL string from the DC power supply through the inverter to emit light, an inductor is provided between the inverter and the EL. An EL light emitting power supply circuit characterized by the following.

(2) It has a DC power supply and an impark circuit, applies an AC voltage load from this DC power supply to a bipolar capacitor via an inverter, and provides a transformer between the inverter and the bipolar capacitor, and a secondary An ELL optical power supply circuit characterized in that an EL or an EL array is turned on using AC output power from a side coil.

(3) The ELL optical power supply circuit according to (1) or (2) above, wherein a bipolar capacitor is connected in parallel to the EL.

(4) The inductance of the inductor or transformer reduces the current during the switch opening/closing operation of the inverter, and the charge that has been charged up in the EL and/or bipolar capacitor via the inverter and inductor or transformer is transferred to the supply power. The ELL optical power supply circuit according to any one of (1) to 3) above, wherein the ELL optical power supply circuit collects backflow current to the side.

(5) The EL power source circuit according to any one of (1) to 4) above, wherein a buffer capacitor is provided between the inverter and the DC power source. The ELL optical power supply circuit according to any one of (1) to 5) above, wherein a second inverter that performs an opening/closing operation opposite to that of the inverter is provided in between.

(7) The ELL optical power supply circuit according to (6) above, wherein a phase control coil is provided between the DC power supply and the second inverter.

(8) The ELL optical power supply circuit according to any one of (1) to 7), wherein the frequency and/or pulse width duty ratio of the switching signal wave of the inverter can be variably set.

(9) The inverter is composed of a charging inverter and a feedback inverter, both inverters are driven by a switching signal wave of the same frequency at the same rising edge, and the pulse width duty of the feedback inverter is
The ELL optical power supply circuit according to any one of (1) to 8) above, wherein the ratio is larger than the pulse width duty ratio of the charging inverter.

Effect> It is possible to make the EL emit light by shifting the phases of the load voltage and current by some method to reduce the switching loss.

In addition to this, the present invention aims to recover surplus power from the load by using a reverse current, so that the following two effects can be realized simultaneously in terms of energy efficiency.

■ By shifting the phase of load voltage and load current, switching energy loss due to power transistors and power MO3FETs is eliminated.

■Improve power efficiency by recovering surplus load power for EL using reverse current.

<Example> A specific circuit configuration of the first aspect of the present invention will be described with reference to FIG.

In the power supply circuit of the present invention, a pair of switches Tr+
, Trz is connected to the +E1-H DC power supply.

The inverter may be any known inverter, and the switches Tr+ and Trz are alternately opened and closed depending on the switching signal frequency f. Switch T r + T
As r w, it is preferable to use a power transistor with a breakdown voltage of 2E or more, a power MOSFET, or the like to configure a push-pull inverter.

In addition, in the illustrated example, the power M is used as T r + , T r 2 and T r s , T r 4 described later
O3FET is used, but Tr+Trx, Trs
, Tr4 may be a power transistor, a normal transistor, a MOS FET, or the like.

When using a power MO3FET, normally P channel and N channel complementary bare switches are selected as switches T r + and T r 2, respectively. For example, enhancement mode (Normal)
As a power MOSFET (ly off mode),
Hitachi's r2sK310J and r2sJ117J can be used.

An inverter having such switches Tr+ and Trz is connected to EL with a capacitance C and grounded.

A coil L is connected as an inductor between the EL and the inverter.

The relationship between L and C is given by f=1/4πi (ideal state) if the R component of the circuit or the equivalent component of R is negligibly small. Since the capacitance C of the load EL is known in advance and the frequency f is determined depending on the desired brightness, L can be determined by taking f and C as given.

π is pi.

In addition, normally f is 501 (z ~ 600Hz, C is 0.1μ
Since F is about 10 μF, L is about 30 mH to 10 H.

With this circuit configuration, when a load is applied to EL, EL
The voltage value ■ and current value applied to are the R (resistance component) of the circuit.
If it is assumed to be negligibly small, the result will be as shown in FIG.

In other words, te. =1/2f=2π5[], and the load voltage ■ is 2. It changes with an amplitude of ±2E with a period of .

At this time, the load current ■ is out of phase due to the presence of the coil L, and furthermore, the phase is τ.

It changes with an amplitude of ±CE/−J□− with a period of .

Therefore, during the opening/closing operation of the switches T r + and T r 2 (at the instant of the opening/closing operation), almost no current flows through the circuit.

Therefore, although the loss is not zero due to R etc., the energy loss at that time can still be extremely small.

As a result, the current in the inverter circuit becomes zero or extremely small at the time of rising or falling of the opening/closing operation of the switch, and the switching energy loss becomes extremely small.

Furthermore, as is clear from the above, when coiling, f=1/4
In addition to the inductance determined by πi, the maximum current capacity that can be passed through the coil must be greater than 1, = CE/ff.

Further, it is necessary to select a core material for the coil that has good magnetic flux transmittance at the frequency f.

Now, when the EL is loaded using this method, one switch of the inverter in the switching section, for example, T
The voltage between the drain and source of r +. 3 and current■DI
+ becomes as shown in Figure 3a. Further, the voltage VtL applied to EL is as shown in FIG. 3b.

That is, ■D11 of the switch T r + is τ. ~
2. It is a rectangular pulse voltage of 2E between. On the other hand, engineering. The phase of S is shifted by the coil, and between 0 and τ0, the charge charged up to EL flows through the coil as a positive current a, and as the load current ■ reverses, ,~T,. During this period, a reverse current will flow.

The shaded part of IDB in Fig. 3a is the reverse current,
The electric power (charge) corresponding to this is recovered as surplus electric power to the same power source.

In the above, if R (resistance component) is zero and the energy required for EL light emission is zero, the areas of a and b in FIG. 3a will be equal, and in fact, it will be like a perpetual motion machine. However, this is possible; in reality, power is consumed by the R equivalent component of the circuit, the magnetic field loss in L, the luminous energy of EL, etc., and as shown in the figure, a > b. Become.

Moreover, b is considerably larger than a.

On the other hand, (1) also does not have a clean, symmetrical waveform as shown in FIG. 2, but is vertically shifted by ±ΔE as shown in FIG. 3b. In other words, the charge corresponding to ΔE−C could not be returned due to the light emission of the EL, dielectric loss, and the like.

However, the important thing is that the power equivalent to the area is
This is definitely recovered on the power supply side, which is a fact that improves power efficiency. In conventional EL light emitting systems, the power corresponding to this backflow component is wasted to the other side's power source, and even if it does not become a switching loss, it is wasted as a loss in the power transmission line.

Here, the principle of power recovery will be explained in more detail using the LCR circuit shown in FIG. 4.

In such an LCR series circuit, the voltage across the capacitor C after the switch S is closed. , the change over time of the current I in the circuit is known as the dynamism of the transient phenomenon of the LCR circuit (as is known, as shown in FIG. 5. In this case, τ1, τ0 are L, C
, H is a time constant determined by the values of .

The lighting method of the present invention assumes that the capacitor C is an EL or a bipolar capacitor which will be described later, and that the switch S is likened to one of the switching elements of an inverter.
time constant τ.

Switching is performed while synchronizing at the center.

That is, the lighting system of the present invention utilizes the vibration phenomenon, which is a transient phenomenon in the LCR circuit. The transient phenomenon when the power source is set to +E as shown in FIG. 4 and the transient phenomenon when the power supply is set to -E (not shown) are determined by a time constant τ.

By switching alternately in synchronization with the lighting circuit, a stable steady state of the lighting circuit is achieved.

However, in the LCR circuit, when the value of R exceeds a certain value, the vibration phenomenon shown in FIG. 5 does not occur. In other words, in the lighting circuit of the present invention, when the equal polarized component corresponding to R is equal to or greater than a certain value, no backflow of charges occurs.

The equal polarized components of the lighting circuit corresponding to R of the LCR circuit are resistance in the circuit, magnetic flux loss of the coil, DC resistance of the coil, magnetic flux saturation of the coil, dielectric loss in the EL, luminous flux divergence in the EL, etc., and this R The smaller the equivalent component is, the greater the backflow current, that is, the amount of charge feedback, and if it is zero, the ideal state as explained based on FIG. 2 is achieved.

Therefore, when configuring a lighting circuit, the selection of the coil is important, and special care must be taken to meet the above conditions, and it is desirable that the switching element has as little on-resistance as possible.

In the lighting circuit of the present invention, the power supply voltage is switched from +E to -E, but the setting can be done using various known methods (e.g., by adjusting the switching frequency f, All you have to do is synchronize.

In this case, if the synchronization is erroneously performed with τ1, the circuit becomes extremely unstable, which may lead to damage to the EL, so care must be taken.

In the present invention, the electric charge that has been charged up to the EL is recovered by the force of the coil to the same power source to which this electric charge was supplied, thereby reducing the loss of the electric charge to the other power source. It improves efficiency.

For example, if you want to make the inductance smaller than f=1/4πi in an ideal circuit, as shown in FIG.
A bipolar capacitor C0' may be connected in parallel with .

And the capacitance Co of this dummy capacitor
' and the capacitance C8 of EL is set as C, and the inductance obtained from this equation can be set.

However, in such a case, although the inductance can be made small, the current value, especially the maximum current value 1. ,
, = CE/- "17 stones" will be increased, so the diameter of the coil must be increased to compensate for the decrease in inductance.

Also, most switching devices such as power MOSFETs do not only flow drain-to-source as long as the channel is open (current flows almost the same from source-to-drain, but from drain-to-source). When using a switching element with diode characteristics only in the source direction, such as a power transistor, use an appropriate diode D II, D, 2, DI8, DI4, D2+, D2□
, I) as, D 24 to create a configuration as shown in FIG.

With such a configuration, both forward current and reverse current always flow only from the collector to the emitter or from the emitter to the collector in the switching element.

In the present invention, there is no particular restriction on the DC power source used.

However, the present invention is particularly effective in terms of power saving when a secondary battery power source or a solar battery power source is used as a power source.

However, recharging the secondary battery with the reverse current not only shortens the current life but also may be difficult due to the characteristics of the battery itself.

Therefore, when a battery is used as a power source, diodes D, D2 are inserted between the power source and switching elements Tr+ and Trg, as shown in FIG. 8, and capacitors C, C, are provided as reverse power buffers. It is preferable.

Alternatively, as shown in FIG. 9, the buffer capacitors CI, C, and the same frequency f on the power supply side
It is also preferable to connect a second inverter having switching elements T r m , T r a which switch at 1 and are closed during reverse flow. On this occasion,
One solution is to further provide coils La and L3 as phase adjustment inductors between the inverter and the power source.
In this case, since it is possible to prevent the power supply from charging the capacitor C3 when charge is supplied to the EL and when charge flows backward from the EL, the loss can be further reduced by a considerable amount.

Alternatively, as shown in FIG. 10, if the coil L3 is provided after the second inverter having T r s and T r a connected to the power source, only one coil is required.

At this time, in FIGS. 9 and 10, f l= f
t, Trs is closed when Tr+ is in the oven, and Trs is in the oven when Tr+ is closed.

That is, the oven closing relationships of Tr+, Tri, Tri, and Tr4 are as follows.

0~τ0 τ. ~2 τ0T r +
Oven Close Trg Close
Oven T r s Close
Oven Tr4 Oven closed,
In this case, 1/C = 1/C, + 1/C2 (C
1 is EL), then the relational expression f=1/4π in the previous ideal state holds true as is.C+>>C
In the case of 2, it may be set at Cα02.

In addition, the coil L3 is inserted into the switching element T.
This is to avoid switching energy loss at rs, Tr<, and the relationship between L3 and C1 is still f≧1/
It is sufficient to set it to around T.
At this time, the loss is reduced to almost zero.

Note that when a plurality of ELs are connected to one DC power source, the plurality of ELs may be connected in parallel after the coil L.

When lighting an EL using the lighting circuit of the present invention, the EL
The dynamism of the charge operation within the circuit that returns the charged up charges as a reverse current is determined by the capacitance of the EL and capacitor, the inductance of the inductor, and the frequency and waveform of the switching signal.

Therefore, in order to light an EL using the lighting circuit of the present invention, these three parameters must be well matched.

There is no limit to the method of fitting the parameters, and various known methods may be used, but the method described below is preferably used because it is easy to operate.

■A method of setting the duty ratio by fixing the switching frequency f(τ) of the inverter and making the duty ratio of the pulse width variable (the ratio of the switch open period -co to the half period τ, 2L0/τ). .

■The duty ratio is fixed and the switching frequency f
A method of keeping f variable and setting the switching frequency f.

(2) A method in which both the switching frequency f and the duty ratio are made variable and both are set.

Using such a method is effective because it can accommodate a wide range of changes in required brightness and when using ELs with different capacitances without changing the inductor.

In particular, the duty ratio setting method (■) is suitable for lighting a small area EL at a relatively low frequency without increasing the size of the coil.

In addition, in FIG. 11, the frequency f is fixed and the duty factor is
Ratio τ. The switching waveform and drain-source current (2) when /τ is set to be smaller than 1 are shown.

When using such a method, for example, the switching frequency and duty ratio may be adjusted and set while observing the current and voltage waveform between the drain and source of one switching element of the inverter using an oscilloscope or the like.

The switching frequency and duty ratio are adjusted and set, for example, by operating a volume for adjustment and setting provided in the oscillation circuit.

Next, the regression synchronization of the reverse flow feedback current is automatically set without manual operation such as volume adjustment.
The L lighting circuit will be explained.

The circuit shown in FIG. 12 uses an automatic setting method that sets the frequency f and follows the current mode.

In this circuit, a charge-up path for a forward current flowing from a power source to an EL and a feedback path for a reverse current are provided separately between the power source and the inductor.

In this case, a charging inverter having inverter switches T r + and T r 2 and a return impark having Tri and Tr4 are provided in each path. Each path also includes a diode D1.
D2. D,, regulated by D4.

Then, each inverter is turned on and off using different signal waves f1 and f2 in accordance with the EL lighting frequency f.

In such a circuit, charges from the positive power supply side are charged to EL through Tr+ as a positive direction current, and T r
It is fed back as a reverse current through s.

Furthermore, charges from the negative power supply side are similarly charged through Trz and fed back through Tr<.

In this case, if fl and f2 are forward synchronization pulses, Tr
+, Tr3 is of the same channel, T r 2 , T
The same channel is also used for r4, and complementary pairs of different channels are selected for T r + and T r z and T r s and T r 4, respectively.

On the other hand, if f+ and fz are synchronization pulses that are inverted with each other, T r + and T r z are of different channels,
Tra and Tr4 are also of different channels, and Tr
+ and T r 2 and T r s and T r a select different complementary pairs of channels, respectively.

The signal wave f1 for switching T r 3 and T r 4 of the feedback inverter is a rectangular wave, and its frequency is set to be the same as the lighting frequency f of the EL. Note that the duty ratio of the pulse width of the signal wave f1 is τ. /τ
Any value greater than or equal to that is sufficient, and is selected to be a predetermined value, which is usually a fixed value. In the illustrated case, the duty ratio is 1.

On the other hand, the signal wave f2 for switching the charging inverter Tr, Trz is a rectangular wave, and its frequency is set to be the same as the EL lighting frequency f. The duty ratio 2/τ of the pulse width 2 of the signal wave f2 may be fixed or variable, but there are certain restrictions as will be described later. /τ or less, preferably τ1/
So that's it, τ. /τ or less.

Note that the frequency and duty ratio are arbitrary as long as the above conditions are satisfied, and are determined as appropriate.

Here, regarding the operation of charging and feedback from the positive power supply side, the drain-source current of Tr+ and Tra is 1.
This will be explained using 3Dg and signal waves f+ and f2.

Signal waves f, , f and currents III, Il, 8I, s
is as shown in FIG.

In addition, the current waveform shown by the dotted spring in the figure is the drain-source current flowing through Trt and Tr4 on the negative power supply side.
゜i, I'os.

In the lighting circuit shown in FIG. 12, the time constants τ1 and τ.

is a variable value determined by the capacitance, inductance, resistance, etc. in the circuit, but as shown in FIG. 13, the value of the pulse width -c2 is τ, or possibly. does not have to be the same as However, as mentioned above, τ2≦
τ. Must. If τ2〉τ. So,
This is because the charge returned to the power supply is recharged to the EL through T r +. If 2<τ1, switching energy loss becomes a problem, so it is preferable that τ2≧τ1.

However, in this lighting circuit, τ2≦τ. As long as this is true, current feedback can be automatically realized even if the signal waves f+ and fx are set once and then fixed. Therefore, even if the value of τ0 changes due to a change in capacitance over time, which is the weak point of EL, the current backflow feedback mode is automatically achieved.

When an EL is left on for many years, its capacitance decreases. Therefore, if the automatic setting method is not used, as shown in FIG. 14, the switching frequency f will initially match the value of τ of the switching frequency f. As the value of τ decreases. Which timing is off? In addition, in Figure 14, ■.

. The drain-source current I'D9 at the time of setting is the drain-source current after the EL changes over time. Further, (+) indicates the current on the positive power supply side, and (-) indicates the current on the negative power supply side.

In such a case, a recharging current shown in the shaded area shown in FIG. 14 occurs, which causes a decrease in the EL lighting efficiency.

However, if the automatic setting method shown in Fig. 12 is used,
τ1≦τ2≦τ. As long as this is true, it is possible to eliminate switching loss and prevent the generation of re-charging current due to changes in EL over time.

In this case as well, for the reasons mentioned above, diodes are inserted between the power source and Tr+ and Tr2 of the charging inverter, which are switching elements, as shown in FIG. 15, and a capacitor is also inserted as a reverse power buffer. It is preferable to provide C1 and C3. Or the 9th
If a second inverter or a phase adjustment inductor as shown in FIGS. 1 and 10 is provided, the loss can be further reduced.

Although not shown, the frequency f is τ. 1/2τ automatically according to the change in . An automatic tracking system may be used at a frequency that automatically opens and closes the switch when the reverse current returns completely.

Alternatively, the frequency f may be set variably, and an automatic tracking system of the pulse width duty ratio may be used in which the switch is automatically closed only when the reverse current returns.

These circuits can be realized by using a switching element such as a triac that automatically turns off when the current value becomes zero, and by devising the circuit. Alternatively, this can be realized by devising an oscillation circuit so that the frequency of the switching signal wave of the inverter and its pulse width duty ratio follow in sync when the feedback of the reverse current is achieved.

When lighting an EL according to the present invention, a ±EV dual mode power source is required, and one end of the EL is grounded to an intermediate potential terminal (zero volt terminal). Therefore, when the -order power source is a single mode power source, it is converted into a dual mode power source with an intermediate potential terminal, and then used as an input power source for the lighting circuit of the present invention.

Various known methods may be used to convert a single mode input voltage to a dual mode output voltage.
For example, the following method can be used.

The first method is to use a dual mode DC-DC converter. This method is effective because the voltage can be raised or lowered at the same time.

In addition, when the -order power supply voltage is 2EV, as shown in Fig. 16, the single mode power supply voltage of 2EV is ±
It may be divided into EV and intermediate potential. In this case, terminal 1 is +EV with respect to terminal 2, and terminal 3 is -EV with respect to terminal 2.
becomes.

Therefore, terminal 1.3 may be used as the inverter input power supply terminal, and terminal 2 may be used as the EL ground terminal.

Furthermore, if the -order power supply voltage e■ is not 2EV, the dual-mode DC-DC converter described above may be used, but a single-mode DC-DC converter may be used to e
The voltage of V may be converted to a voltage of 2EV and then divided into ±EV and an intermediate potential using a capacitor as described above.

In these cases, as shown in FIG.
It is effective to provide backflow prevention diodes D, D, between the C-DC converter and the potential dividing capacitor C4, since the capacitor C4 can also be used as a backflow power buffer capacitor.

In addition, the output voltage of DC-DC converters that are available off-the-shelf is limited, and there are especially few types of dual-mode converters, so single-mode DC-DC converters are
An effective method is to use a converter to divide the potential with a capacitor.

Next, an example of the second aspect of the present invention will be described.

In this case, the principle is the same as the first embodiment in that a reverse current is realized.

However, in this case, consideration is given to the case where the DC power supply voltage ±E is further boosted and an AC load is applied to the EL. When the capacitor C1 is provided, the coil L serving as an inductor is replaced with a transformer T, and the EL is turned on by AC power on the secondary side of the transformer T.

That is, the circuit configuration is as shown in FIG. 17 or 1, for example.
The result is as shown in Figure 8.

Further, FIG. 19 shows an example in which a coil L' is further added to this circuit as a compensation inductor.

Although not shown, an example of the second aspect of the present invention is as follows:
It can be used in all the circuits described for the embodiments of the first aspect.

The above description of the embodiment is based on the enhancement mode (normally) switching element of the inverter.
OFF mode), but the same operation can be achieved using a deep gin mode (Normal mode).

Examples of depletion mode power MO3FETs include rMTP2N50J and rMT manufactured by Motorola.
P2P50J can be used.

In this case, normally the positive power supply side is an N channel, and the negative power supply side is a P channel.

<Effects of the Invention> According to the present invention, the inductor (transformer T) provided between the inverter and EL (bipolar capacitor C3) shifts the phase and cycle of the load current and load voltage, so that the opening/closing operation of the inverter switch is At the moment of , all the current in the circuit (no or very little) flows.

This allows power transistors and power MOSFEs to
Switching energy loss of switches such as T is eliminated.

Moreover, a considerable portion of the charge charged up to the EL is recovered as a reverse current to the same power supply side to which the charge was supplied by the force of the inductor (transformer), reducing the loss of flow to the other power supply side. Power efficiency is significantly improved.

Therefore, the luminance and amount of light emitted by the EL can be extremely high.

Moreover, the heat generated by switches such as power transistors and power MOSFETs is significantly reduced, increasing safety.
There is no need to provide heat radiation means.

The present inventors conducted various experiments in order to confirm the effects of the present invention. An example is shown below.

Experimental example Four blue-green ELs with a light emitting area of 572 cm2 (C = 200 nF) were used and connected in parallel, and E = 14.
Each EL was driven by push-pull at f=400Hz with an inverter using a power MO3FET at 0V.
The emission intensity and the heat generation amount of the power MOS FET are:
It was as shown in Table 1 below.

On the other hand, according to the present invention, 50
When mH wires were connected, the results were as shown in Table 1 below.

Table 1 Present invention 500Lx 42℃Next, four dispersion EL panels of the same blue-green color with a light emitting area of 572 cm2 (C=200nF) each were connected in parallel at a frequency of 400Hz and an effective voltage E=60. .80
．． We will compare the power consumption per EL unit area (1cm") when illuminated at 100.120.140■.The comparison was made with a conventional EL in which a sine wave effective value E of 400Hz is directly applied to the EL. The lighting method and the method of the present invention. In this case, in the present invention, f = 400 Hz, L = 5
It was set to 0 mH.

Table 2 (Conventional) E: Effective voltage (V) 60 80 10
0 120 140 Brightness [Cd7m”1 Surface illuminance [Lxl Power consumption 12.6 24.6 38.2 52.
33.30 6.48 11.40 18
．． 2466.8 27, 58 Table 3 (present invention) E: Effective voltage (V) 60 80 too 120
140 Brightness [Cd7m”1 Surface illuminance [Lxl Power consumption 24.8 43.0 68.4 117.
8 159.22.814 5.032 6
．． 8g 9.108 12.125 or more As can be seen by comparing the actual measured values, the present method shows a significant improvement in both brightness and power consumption compared to the conventional method.

What is surprising is that even though the frequency and effective voltage are the same, there is a significant improvement in both brightness and power consumption for all voltage parameters, and the fact that brightness has increased and power consumption has decreased. It is. The synergistic effect of improving brightness and improving power consumption can be quantitatively understood more clearly when the objective is to obtain the same brightness, that is, when brightness is determined as a parameter.

In Tables 2 and 3, there is a point in common that happens to give the same surface illuminance. That is, 80V, 78Lux in Table 2 and 60V, 78Lux in Table 3.
140V in Table 2.

214Lux and 100V, 215Lux in Table 3.

Regarding 78Lux, the power consumption in Table 2 is 6,
48 m/mVA Table 3 is 2.814 m/mVA,
The power consumption in Table 3 is 1/2.3 of Table 2, or approximately 43%,
Looking at 214Lux, the power consumption in Table 2 is 27
．． 58 m/mVA, Table 3 shows 6.88 m/mVA, which is about 1/4.

From the above, the effects of the present invention are clear.

[Brief explanation of drawings]

Figure 1, Figure 6, Figure 7, Figure 8, Figure 9, Figure 10,
Figures 12, 15, 17, 18 and 19
The figures are circuit diagrams showing different examples of the ELL optical power supply circuit of the present invention. Figures 2, 3a and 3b show the EL negative load voltage, current flow, drain-source voltage V n++ and current I, respectively. 3 and EL are diagrams showing temporal changes in the voltage VEL actually applied to the voltage VEL. FIG. 4 is a circuit diagram showing an LCR series circuit. Figure 5 shows the voltage of capacitor C in the LCR series circuit. FIG. Figure 11 shows the switching waveform and train-source current I when the duplex ratio is set smaller than 1.
FIG. FIG. 13 shows signal waves f+, f- and drain/source current flow 1□ Ix by the automatic reverse feedback current mode setting method of the present invention. *+Ijos, is a diagram showing the time change of I'DI. Figure 14 shows the drain-source current I '''DI % I '-' when the automatic setting method is not used.
Drain-source current I after aging of DI and EL
""os, engineering 1-1. ．． FIG. 2 is a diagram showing changes over time. FIG. 16 is a circuit diagram showing an example of converting a single mode power supply voltage to a dual mode output voltage. C3...Bipolar capacitor

Claims (9)

[Claims] (1) In an EL light emitting power supply circuit that has a DC power supply and an inverter circuit and applies a voltage load to the EL or EL string from the DC power supply through the inverter to emit light, an inductor is provided between the inverter and the EL. An EL light emitting power supply circuit characterized by the following. (2) It has a DC power supply and an inverter circuit, applies an AC voltage load from the DC power supply to a bipolar capacitor via an inverter, and provides a transformer between the inverter and the bipolar capacitor, and the secondary side of this transformer. An EL light emitting power supply circuit characterized by lighting an EL or an EL array using AC output power from a coil. (3) The EL light emitting power supply circuit according to claim 1 or 2, wherein a bipolar capacitor is connected in parallel to the EL. (4) The inductance of the inductor or transformer reduces the current during the switch opening/closing operation of the inverter, and the charge that has been charged up in the EL and/or bipolar capacitor via the inverter and inductor or transformer is transferred to the supply power. The EL according to any one of claims 1 to 3, wherein the EL is collected as a backflow current to the side.
Light emitting power circuit. (5) The EL light emitting power supply circuit according to any one of claims 1 to 4, wherein a buffer capacitor is provided between the inverter and the DC power supply. (6) The EL light emitting power supply circuit according to any one of claims 1 to 5, further comprising a second inverter that performs an opening/closing operation opposite to that of the inverter, provided between the inverter and the DC power supply. (7) The EL light emitting power supply circuit according to claim 6, further comprising a phase control coil provided between the DC power supply and the second inverter. (8) The EL according to any one of claims 1 to 7, wherein the frequency and/or pulse width duty ratio of the switching signal wave of the inverter can be variably set.
Light emitting power circuit. (9) The inverter is composed of a charging inverter and a feedback inverter, and both inverters are driven with a switching signal wave of the same frequency at the same rise, and the pulse width duty ratio of the feedback inverter is 9. The EL according to claim 1, wherein the pulse width duty ratio of the charging inverter is larger than the duty ratio of the charging inverter.
Light emitting power circuit.