JPH07153586A - Lighting system - Google Patents

Abstract

PURPOSE:To start a lighting system reliably by applying sufficient starting voltage to a lamp load. CONSTITUTION:High frequency electric power supply A outputs a high frequency current having a constant amplitude to a series circuit of the primary winding of electric current transformers T1, T2,.... Discharge lamps FL1, FL2,... are respectively connected to the secondary winding of the respective electric current transformers T1, T2,.... A starting control circuit C makes an electric current amplitude of the high frequency current in the series circuit of the primary winding of the electric current transformers T1, T2,... larger in a constant period than at steady lighting time. Thereby, since starting voltage higher than at the steady lighting time can be intermittently impressed on the discharge lamps FL1, FL2,..., startability is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device for supplying a high frequency current output from a high frequency power source to a lamp load through a current transformer and lighting the lamp load.

[0002]

2. Description of the Related Art Conventionally, as shown in FIG. 10, a high-frequency power source A that outputs a constant high-frequency current is used to light a plurality of discharge lamps FL _{1 to} FL ₃ such as fluorescent lamps, which are lamp loads. A lighting device according to the above has been proposed. The lighting device, lighting fixture B ₁ comprise along with current transformer T ₁ through T ₃ corresponding to the discharge lamps FL ₁ to FL ₃ respectively
Has .about.B _3, each luminaire B ₁ .about.B ₃ is arranged in a dispersed away from the high frequency power source A. The high frequency power supply A is
It is those commercial power source Vs is inputted to output a high frequency constant current, the primary winding of the series circuit of the current transformer T ₁ through T ₃ is connected between the output ends, the current transformer T ₁ through T
_The discharge lamps FL _{1 to} FL ₃ are connected between both ends of the secondary winding of No. ₃ , respectively. Each of the current transformers T _{1 to} T ₃ has a structure in which a secondary winding is wound around an iron core that forms a closed magnetic circuit like a toroidal core, and one electric wire to be the primary winding is installed in the iron core. The primary winding and the secondary winding are electromagnetically coupled to each other by being inserted into.

The configuration of FIG. 10 will be described in more detail. As shown in FIG. 11, the commercial power supply Vs is input to a full-wave rectification circuit 2 composed of a diode bridge through a noise prevention filter circuit 1 composed of a choke coil L ₁ and two capacitors C ₁ and C ₂ and is fully input. Wave rectified. The filter circuit 1 is a low-pass filter and has a function of reducing current feedback noise and input current distortion. A chopper circuit 3 is connected between the DC output terminals of the full-wave rectifier circuit 2. The chopper circuit 3 is
A switching element Q ₁ composed of a MOSFET, an inductor L ₂ for energy storage, and a smoothing capacitor C
It has a series circuit with ₄ and this series circuit is a full wave rectifier circuit 2
Connected between the DC output terminals of. Also, inductor L
A diode D ₁ for flowing a regenerative current is connected to the series circuit of ₂ and the capacitor C ₄ with the polarity shown. Further, a high-frequency bypass capacitor C ₃ is connected between the DC output terminals of the full-wave rectifier circuit 2. The switching element Q ₁ is, are high frequency turned on and off by the chopper control circuit 31, the ON period of the switching element Q _1, the switching element Q ₁ - inductor L ₂ - inductor L ₂ and a current flows through a path of the capacitor C ₄ the energy is stored, the energy stored in the inductor L ₂ is in the oFF period of the switching element Q _1, a capacitor C ₄ - is being discharged through the diode D _1.
Therefore, the terminal voltage of the capacitor C ₄ is determined by the ratio of the ON period and the OFF period of the switching element Q ₁ , and the chopper circuit 3 outputs a DC voltage lower than the input voltage.

The output of the chopper circuit 3 is supplied to the inverter circuit 4. The inverter circuit 4 includes a pair of four switching elements Q _{2 to} Q ₅ each composed of a MOSFET connected in series, and a bridge circuit of switching elements Q _{2 to} Q ₅ in which both series circuits are connected in parallel. A series resonant circuit including an inductor L ₃ and a capacitor C ₅ is connected between the connection points of the pair of switching elements Q ₂ , Q ₃ , Q ₄ , Q ₅ . The capacitor C ₅ is connected parallel primary winding of the isolation transformer Tf, the secondary winding of the isolation transformer Tf, the sine wave filter circuit consisting of the choke coil L ₄ and two capacitors C _6, C ₇ A series circuit of the load circuit 5 and the primary winding of the current detection transformer CT is connected via the. As the load circuit 5, as shown in FIG. 10, the current transformers T _{1 to} T ₃ and the discharge lamp FL _{1 are used.}
To FL ₃ are used.

Each switching element Q of the inverter circuit 4
_{2 to} Q ₅ are on / off controlled at high frequencies by the output of the inverter control circuit 41. Inverter control circuit 4
1 divides the output of the oscillation circuit 42, for each pair in the switching element _{Q 2, Q 5, Q 3} , and Q ₄ pairs of diagonal positions of the bridge circuit composed of switching elements Q ₂ to Q ₅ Outputs that alternately turn on and off are generated. That is, while the switching elements Q ₂ and Q ₅ are on, the switching elements Q ₃ and Q ₄ are off and the switching element Q
_3, the period of the Q ₄ is turned on, the switching element Q _2, Q
₅ is off. Therefore, the high frequency current flows through the primary winding of the insulating transformer Tf, and the high frequency current is supplied to the load circuit 5.

By the way, the secondary winding of the current detection transformer CT in which the primary winding is connected in series to the load circuit 5 has a center tap, and the output at both ends of the secondary winding is the diode D ₂ ,
Full-wave rectified by D ₃ and input to the current detection circuit 6,
The current detection circuit 6 outputs a voltage value according to the input current.
The output voltage of the current detection circuit 6 has a constant voltage Vcc and a resistance R
₁ is input to the differential amplifier circuit 7 together with the reference voltage divided by the variable resistor VR, and the output of the differential amplifier circuit 7 is input to the chopper control circuit 31, whereby the chopper circuit 3 is transferred to the load circuit 5. Feedback control is performed in the direction in which the supplied current is kept constant.

A soft start circuit 8 is connected to the AC input terminal of the full-wave rectifier circuit 2 via diodes D ₄ and D ₅ , and the soft start circuit 8 has a commercial power source V.
When the input of s is detected, the chopper control circuit 31 is controlled so that the supply current to the load circuit 5 increases to a constant current with the passage of time. As described above, the chopper circuit 3 and the inverter circuit 4 constitute the high frequency power supply A.

Next, the operation of the above circuit will be described. When the commercial power supply Vs is turned on, the soft start circuit 8 operates as described above, and the on-duty of the switching element Q ₁ is controlled to gradually increase. In addition, after the control by the soft start circuit 8 is completed and the steady state is entered, the load current supplied to the load circuit 5 is detected through the current detection transformer CT, and the switching element Q is detected according to the magnitude of the load current. By adjusting the on-duty of ₁ , the output voltage of the chopper circuit 3 is changed so as to keep the load current constant.

In the inverter circuit 4, each of the switching elements Q _{2 to} Q ₅ is switched at a constant frequency in the range of 40 to 100 kHz, so that the isolation transformer Tf is converted.
A high-frequency current through the primary winding of the inductor L ₃ , a series resonant circuit including an inductor L ₃ and a capacitor C ₅ , an insulating transformer Tf, an inductor L ₄ , capacitors C ₆ , C
_A sine wave filter circuit composed of ₇ etc. is configured to output a current having a current waveform close to a sine wave.
Thus, when the output current waveform is close to a sine wave, the radiation noise generated from the wiring path that feeds the load circuit 5 can be significantly reduced as compared with the case where the output current waveform is a rectangular wave. Further, the output of the inverter circuit 4 is the isolation transformer T.
Since insulation is provided via f, it is possible to prevent the risk of electric shock during construction, and reduce leakage current to the ground to reduce wiring loss.

[0010]

By the way, in the above-mentioned conventional configuration, the discharge lamps FL _{1 to} FL ₃ are used in the load circuit 5, and the lamp loads such as the discharge lamps FL _{1 to} F ₃ are not used. It is known that it is necessary to apply a higher voltage at the time of starting than at the time of steady lighting. Therefore, in order to improve the startability of the discharge lamps FL _{1 to} FL ₃ , it is conceivable to increase the winding ratio of the current transformers T _{1 to} T ₃ used in the load circuit 5 to generate a sufficiently high starting voltage. To be However, the lamp current of the discharge lamps FL ₁ to FL ₃ is primary current × the current transformer T ₁ through T ₃
(The number of turns of the primary winding / the number of turns of the secondary winding), and the output current of the high-frequency power supply A, which is the primary side current, is kept constant, so the secondary of the current transformers T _{1 to} T ₃ Discharge lamp FL on the side
If the rated current of _{1 to} FL ₃ is to be obtained, the winding ratio of the current transformers T _{1 to} T ₃ is uniquely determined, and the winding ratio cannot be increased, and the discharge lamps FL _{1 to} FL ₃ are not able to be increased. However, there is a problem that the startability of the vehicle cannot be improved.

An object of the present invention is to solve the above-mentioned problems, and it is possible to give a sufficient starting voltage to a lamp load so that the lamp load can be reliably started. It is intended to provide a lighting device.

[0012]

According to a first aspect of the present invention, a series circuit of primary windings of a plurality of current transformers is connected between output terminals of a high-frequency power source that outputs a high-frequency current with a constant amplitude, and each current is connected to the other. In a lighting device in which a lamp load is connected between both ends of a secondary winding of a transformer for lighting, a current superposition means for intermittently superposing a large amplitude current having a current amplitude larger than the high frequency current on the high frequency current is provided. It is characterized by consisting of.

According to a second aspect of the invention, in the first aspect of the invention, there is provided a current control means for stopping the large amplitude current when the output voltage of the high frequency power source reaches a predetermined threshold value.

[0014]

According to the structure of the invention of claim 1, a large amplitude current having a larger current amplitude than the constant amplitude high frequency current output from the high frequency power supply is intermittently superimposed on the high frequency current output from the high frequency power supply. By providing the current superimposing means, it is possible to intermittently flow a large amplitude current to the primary winding of the current transformer, and intermittently to the lamp load connected to the secondary winding of the current transformer. By applying a high voltage, the lamp load can be easily started. That is, the startability of the lamp load is improved. Further, although a plurality of lamp loads are provided, a high voltage is sequentially applied to each lamp load to start and light them in order, so that all of the plurality of lamp loads can be reliably turned on.

According to the second aspect of the present invention, when the output voltage of the high frequency power source reaches a predetermined threshold value, the large amplitude current is stopped so that all the lamp loads are started and turned on. After all the lamp loads are lit by voltage detection, stop the unnecessary large-amplitude current to keep the current amplitude constant and prevent flickering of the lamp load and radiation noise. You can

[0016]

【Example】

(Basic Structure) The present invention is basically as shown in FIG.
10 is different from the conventional configuration shown in FIG. 10 in that a start control circuit C as a current superimposing means for periodically superimposing a high-amplitude high-frequency current on a high-frequency current of a constant amplitude output from the high-frequency power supply A is added. It is different. That is, in the starting control circuit C, the discharge transformers FL _{1 to} FL ₃ serving as lamp loads are connected to the secondary windings of the current transformers T ₁ to FL _3.
The amplitude of the high frequency current I flowing through the series circuit of the primary winding of T ₃ is periodically increased as shown in FIG. 1 (b).

(Embodiment 1) FIG. 2 shows a specific configuration for realizing the above basic configuration. The high frequency power supply A of this embodiment uses a direct current power supply E such as a battery as an input power supply, boosts the direct current voltage by the chopper circuit 3, and then generates a high frequency current by the inverter circuit 4 and supplies the high frequency current to the load circuit 5. Configured. Further, the start control circuit C controls the inverter control circuit 41 to cause the inverter circuit 4 to operate.
It is constituted by a starting pulse control circuit 11 which periodically makes a high-frequency current output from the device have a large amplitude.

In the chopper circuit 3, a series circuit of an inductor L ₁₀ and a switching element Q ₁₀ is connected across the DC power source E, and a series circuit of a diode D ₁₀ and a capacitor C ₁₀ is connected in parallel with the switching element Q _10. In addition, a high-frequency bypass capacitor C ₁₁ is connected between both ends of the DC power source E. As is well known, the switching element Q ₁₀ is controlled by the chopper control circuit 31 to be turned on and off at a high frequency.
_The energy accumulated in the inductor L ₁₀ during the on period of ₁₀ is added to the output of the DC power source E during the off period of the switching element Q ₁₀ and is given to the capacitor C ₁₀ .
The terminal voltage of the capacitor C ₁₀ is set to be higher than the input voltage of the DC power source E. The terminal voltage of the capacitor C ₁₀ changes depending on the on-duty of the switching element Q ₁₀ .

The chopper control circuit 31 includes a triangular wave oscillator 3
An output monitoring circuit 10 including a PWM control circuit 2 and a comparator 33, which has a configuration corresponding to the current detection circuit 6 and the differential amplifier circuit 7 in the conventional configuration shown in FIG.
The comparator 33 is configured to output a rectangular wave having an on-duty corresponding to the control voltage by comparing the control voltage from the output voltage of the triangular wave oscillator 32 with the output voltage of the triangular wave oscillator 32. That is, the output frequency of the chopper control circuit 31 is determined by the output frequency of the triangular wave oscillator 32, and as shown in FIG. 3A, the output voltage Vt of the triangular wave oscillator 32 is higher than the control voltage Vc from the output monitoring circuit 10. Since the on-duty is determined so as to turn on the switching element Q ₁₀ during the period (see FIG. 3B), the switching element Q ₁₀ is controlled by the PWM method. Therefore, when the output voltage of the output monitoring circuit 10 rises, the on-duty of the switching element Q ₁₀ becomes small and the output voltage of the chopper circuit 3 drops.

The inverter circuit 4 has the same structure as the conventional structure shown in FIG. 11, and a DC blocking capacitor C ₁₂ is added to the series resonance circuit of the inductor L ₃ and the capacitor C ₅ and connected in series. There is. In addition, the switching elements Q _{2 to} Q ₅ that form the inverter circuit 4 are
It is controlled by an inverter control circuit 41 which generates a control signal as will be described later based on the output of 2. Between the both ends of the secondary winding of the isolation transformer Tf, current transformers T ₁ and T in which discharge lamps FL ₁ and FL ₂ are connected to the secondary windings, respectively.
A series circuit of the primary winding of No. ₂ and the current detection means 9 such as a current detection transformer is connected. The current detection means 9 detects the load current supplied to the load circuit 5 and inputs the detected load current to the output monitoring circuit 10 to adjust the output voltage of the chopper circuit 3 in accordance with the load current to The current is kept almost constant. That is, when the load current increases, the control voltage output from the output monitoring circuit 10 rises, the output voltage of the chopper circuit 3 is lowered, and as a result, the output current of the inverter circuit 4 decreases. Similarly, if the load current increases, the output voltage of the chopper circuit 3 increases and the output current of the inverter circuit 4 increases.

The inverter control circuit 41 uses a PS (Phase
-Shifted) Each switching element Q _{2 to} Q by PWM method
Control ₅ That is, in the PSPWM method, as shown in FIG. 4, the time width T for turning on each of the switching elements Q _{2 to} Q ₅ is kept constant, and a pair of switching elements Q ₂ , which are allowed to turn on at the same time, Q ₅ or Q
Regarding ₃ , Q ₄ , the timings of the period in which one is on and the period in which the other is on are shifted (that is, the phase of the on period is shifted), and the switching elements Q ₂ , Q ₅ or Q forming a pair are shifted. _The time width t in which ₃ and Q ₄ are simultaneously turned on can be adjusted. Therefore, the output voltage V _F of the inverter circuit 4 has a cycle of 2T, and is generated every half cycle only during the period t / T.
This means that the phase of a rectangular wave with a constant cycle with alternating polarities is controlled. Here, as the period t / T is longer, the inverter circuit 4
Since the power output increases from can be shifted timing of the on-period of the switching element Q ₂ to Q ₅ so as to extend the period t / T, to increase the load current supplied to the load circuit 5.

Therefore, in the starting pulse control circuit 11, as shown in FIG. 5 (a), the starting pulse having a constant cycle is generated, and during the ON period of the starting pulse, the inverter as shown in FIG. 5 (b) is generated. The inverter control circuit 41 is controlled so that the period t / T in which the output of the circuit 4 is generated is made larger than that during steady lighting. Therefore, the inverter control circuit 41
As shown in FIG. 5C, the current amplitude of the output of the discharge lamp FL ₁ , the voltage generated on the secondary side of the current transformers T ₁ , T ₂ periodically increases, and the discharge lamp FL ₁ , This makes it easier to start FL ₂ . Here, the output monitoring circuit 10 described above feeds back the control voltage corresponding to the load current also to the inverter control circuit 41, and is configured to keep the load current constant by controlling the inverter circuit 4. There is.

(Embodiment 2) In this embodiment, as shown in FIG. 6, one switching element Q is used as an inverter circuit 4.
_A one-stone separately excited inverter circuit that oscillates at ₆ is used. The configuration corresponding to the inverter control circuit 41 and the oscillation circuit 42 for controlling the on / off of the switching element Q ₆ is as follows: a commercially available integrated circuit IC ₁ as a PWM controller for a switching power supply, resistors R _{11 to} R ₁₃ and a capacitor C. ₁₃ and ₁₃ are attached externally. Further, the starting pulse control circuit 11 is configured by using a pulse oscillation circuit 12 that generates a pulse at a constant cycle. Since the integrated circuit IC ₁ determines the on-duty of the switching element Q ₆ by the resistors R _{11 to} R ₁₃ and the capacitor C ₁₃ , the starting pulse generating circuit 11 short-circuits the resistor R ₁₂ at regular intervals, and By connecting the resistor R ₁₄ in parallel with R ₁₃ , the on-duty of the switching element Q ₆ is changed at a constant cycle. Other configurations are the same as those of the conventional configuration shown in FIG. 11, in which a commercial power supply Vs is passed through a filter circuit 1 and full-wave rectified by a full-wave rectification circuit 2 to obtain a DC power supply, which is input to a chopper circuit 3. . The output of the chopper circuit 3 is input to the above-mentioned inverter circuit 4.

In the inverter circuit 4, a series circuit of a primary winding of an insulating transformer Tf and a switching element Q ₆ is connected between the output terminals of the chopper circuit 3, and a capacitor C ₁₄ is connected in parallel to the switching element Q _6. There is. Therefore, by controlling ON / OFF of the switching element Q ₆ , an alternating current can be passed through the secondary output of the insulating transformer Tf.

A series circuit of the primary windings of the current transformers T ₁ and T _{2 and} the primary winding of the current detection transformer CT is connected between both ends of the secondary winding of the isolation transformer Tf, and Discharge lamps FL ₁ and FL ₂ which are lamp loads are connected to the secondary windings of the transformers T ₁ and T ₂ . In addition, the output of the secondary winding of the current detection transformer CT is the diodes D ₂ and D ₃
And a current detection circuit 6 are input to the differential amplifier circuit 7 and a constant voltage is divided by resistors R ₁ and R ₂ to obtain a difference in output proportional to the difference between the reference voltage and the output voltage of the current detection circuit 6. It is output from the dynamic amplification circuit 7. This differential amplifier circuit 7
The output of the chopper circuit 3 is feedback-controlled so as to keep the load current constant.

With the above structure, the pulse oscillation circuit 12 produces a rectangular wave output as shown in FIG. 7 (a) at a constant cycle, and the voltage across the capacitor C ₁₃ changes as shown in FIG. 7 (b). To do. Therefore, the on-duty of the control signal output from the integrated circuit IC ₁ is as shown in FIG.
It increases only during the period when the rectangular wave is output from the pulse oscillation circuit 12, and the output current of the inverter circuit 4 increases during this period as shown in FIG. 7D. Other configurations and operations are similar to those of the first embodiment.

(Embodiment 3) In this embodiment, as shown in FIG. 8, a voltage detection circuit 13 for detecting the output voltage of the inverter circuit 4 is provided in the configuration of the embodiment 1, and the output of the voltage detection circuit 13 is used. The operation of the starting pulse control circuit 11 is controlled. That is, since the voltage detection circuit 13 is connected between both ends of the secondary winding of the insulation transformer Tf to detect the output voltage of the inverter circuit 4, the output current of the inverter circuit 4 is kept substantially constant. Due to the dripping, as the discharge lamps FL ₁ , FL ₂ , ... Light up, the output voltage of the inverter circuit 4 increases stepwise as shown in FIG. 9A. Therefore, a threshold voltage is set according to the output voltage of the inverter circuit 4 at the stage when all the discharge lamps FL ₁ , FL ₂ , ... Are lit (four discharge lamps are assumed in FIG. 9) ( When the voltage detected by the voltage detection circuit 13 exceeds the threshold voltage,
As shown in FIG. 9B, the voltage detection circuit 13 outputs a stop signal to stop the operation of the start pulse control circuit 11. Here, FIG. 9C shows the output from the starting pulse control circuit 11.

With the above configuration, all discharge lamps F
Until the L ₁ , FL ₂ , ... Are started and lighted, a pulse is generated from the starting pulse control circuit 11 and each discharge lamp F
The starting voltage is periodically applied to L ₁ , FL ₂ , ... And the application of the starting voltage is stopped after the discharge lamps FL ₁ , FL ₂ ,. As a result, it is possible to prevent flicker and the like due to intermittent application of the starting voltage during steady lighting. Also,
When the output voltage of the inverter circuit 4 reaches the set threshold voltage, the operation of giving the starting voltage is stopped, so that the discharge lamps FL ₁ , FL ₂ , ... Protection against.

[0029]

According to the first aspect of the present invention, a current superposition is provided in which a large amplitude current having a larger current amplitude than the constant amplitude high frequency current output from the high frequency power supply is intermittently superimposed on the high frequency current output from the high frequency power supply. Since the means is provided, a large amplitude current can be intermittently passed through the primary winding of the current transformer, and intermittently with respect to the lamp load connected to the secondary winding of the current transformer. There is an advantage that a high voltage can be applied to easily start the lamp load.
That is, there is an effect that the startability of the lamp load is improved.

According to the second aspect of the present invention, when the output voltage of the high frequency power source reaches a predetermined threshold value, the large amplitude current is stopped.
It is detected by the output voltage of the high-frequency power supply that all lamp loads have started and turned on, and after all lamp loads have turned on, the unnecessary large amplitude current is stopped to keep the current amplitude constant. As a result, it is possible to prevent flickering of the lamp load and generation of radiation noise. Further, by detecting the load capacity and stopping the starting pulse voltage, it is possible to prevent the lamp loads of more than the rated load lamps from lighting, and there is also an effect of having a protection function against overload.

[Brief description of drawings]

FIG. 1 shows a basic configuration, (a) is a block diagram, and (b) is a block diagram.
Is an operation explanatory diagram.

FIG. 2 is a circuit diagram showing a first embodiment.

FIG. 3 is an operation explanatory diagram of the chopper control circuit according to the first embodiment.

FIG. 4 is an operation explanatory diagram of the inverter control circuit according to the first embodiment.

FIG. 5 is an operation explanatory diagram of the first embodiment.

FIG. 6 is a circuit diagram showing a second embodiment.

FIG. 7 is an operation explanatory diagram of the second embodiment.

FIG. 8 is a circuit diagram showing a third embodiment.

FIG. 9 is an operation explanatory diagram of the third embodiment.

FIG. 10 is a block diagram showing a conventional example.

FIG. 11 is a specific circuit diagram showing a conventional example.

[Explanation of symbols]

3 Chopper circuit 4 Inverter circuit 5 Load circuit 11 Start pulse control circuit 13 Output voltage detection circuit A High frequency power supply C Start control circuit FL ₁ discharge lamp FL ₂ discharge lamp FL ₃ discharge lamp T ₁ current transformer T ₂ current transformer T ₃ current transformer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Fujimoto 1048 Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (2)

[Claims] 1. A series circuit of primary windings of a plurality of current transformers is connected between output terminals of a high-frequency power source that outputs a high-frequency current of a constant amplitude, and each series is connected between both ends of a secondary winding of each current transformer. A lighting device for connecting and lighting a lamp load, comprising a current superimposing means for intermittently superimposing a large amplitude current having a current amplitude larger than the high frequency current on the high frequency current. 2. The lighting device according to claim 1, further comprising current control means for stopping the large amplitude current when the output voltage of the high frequency power source reaches a predetermined threshold value.