JPS6262037B2 - - Google Patents

Description

and selective isolation and supply means 17.

2. A tunable oscillator ballast circuit according to claim 1, wherein means 121 for compensating for transient currents are coupled to said DC potential supply means 7 and said energy storage and selective isolation and supply means 17.

3. A tuned oscillation type ballast circuit according to claim 2, wherein said transient current compensating means 121 is in the form of a Zener diode.

4. The high-frequency output potential supply means 9 includes an oscillator, and the oscillator includes a pair of series-connected transistors that shunt the DC potential supply means, and a series-connected capacitor and inductor that are coupled to these transistors and supply the output potential. A tuned oscillation type ballast circuit according to claim 1, comprising a resonant circuit comprising:

5. The load energizing means 11 includes a first transformer having a primary winding coupled to the high frequency output potential supply means and a secondary winding coupled to the load circuit, the load circuit having a filament. 2. A tuned oscillation type ballast circuit according to claim 1, which includes a lamp and includes a drive winding and a filament winding in which said secondary winding is connected in series.

6 said load energizing means 11 is in the form of a first transformer having a primary winding coupled to said high frequency output potential supply means and a secondary winding coupled to said load circuit; includes a primary winding connected in series to the secondary winding of the first transformer and a secondary winding coupled to the high frequency output potential supply means, and the intermittent current flowing through the load circuit is connected to the drive circuit. 2. A tuned oscillation type ballast circuit according to claim 1, wherein the means generates an intermittent current.

7. said load circuit 13 is in the form of a pair of fluorescent lamps, said load energizing means having a primary winding coupled to said high frequency output potential supply means, and a series circuit each coupled to said pair of fluorescent lamps; a first transformer having three secondary windings comprising a connected filament winding and a drive winding, said drive means 19 comprising at least one of said series connected filament and drive windings of said load energizing means; Tuning according to claim 1, comprising a second transformer having at least one primary winding connected in series with the second transformer and at least one secondary winding coupled to the high frequency output potential supply means. Oscillation type ballast circuit.

8. said load circuit is in the form of a pair of lamps;
The load energizing means comprises a primary winding coupled to the high frequency output potential supply means and three secondary windings each including a series connected filament and a drive winding coupled to the pair of lamps. a first transformer having a primary winding in series with each one of the three secondary windings of the first transformer of the load energizing means; and a pair of the high frequency output potential supply means. A tunable oscillator ballast circuit as claimed in claim 1, including a second transformer having a secondary winding coupled to a respective one of the transistors.

9 said rectifier means is in the form of a voltage doubler rectifier circuit, said voltage doubler rectifier circuit comprising an inductor coupling said load energizing means to a potential reference level, a series connected diode and a capacitor shunting said inductor; A tunable oscillator ballast circuit as claimed in claim 1, comprising a series connected capacitor and a diode coupling the junction of the diode to said energy storage and selective isolation and supply means.

10. The rectifier means includes an inductor of selectable value coupling the load energizing means to a potential reference level, the value of the inductor controlling the power supplied to the load circuit. A tuned oscillation type ballast circuit as described in range 1.

11. Claim 1, wherein the high-frequency output potential supply means includes a pair of series-connected transistors each having a base and an emitter electrode, and a switching auxiliary circuit coupled between the base and emitter electrodes of each of these transistors. Tuned oscillation type ballast circuit described in .

12. A tuned oscillator ballast circuit according to claim 11, wherein said switching auxiliary circuit is in the form of a series connected diode and resistor.

13 an alternating current potential source 3, a direct current potential supply circuit 7 coupled to the alternating current potential source and supplying a pulsating direct current potential to the tuned oscillator 9, an oscillator drive circuit 19, a rectifier circuit 15, charge storage and selective isolation and the tuned oscillator supplies the high frequency output potential to the first transformer 67 of the load energizing circuit 11;
The first transformer has three secondary windings 75, 81, 87, each secondary winding having a filament connected in series to the load circuit 13 and a drive winding. 79,77;85,
83; 91, 89, said oscillator drive circuit having a second transformer 99, said second transformer connecting said series connected filaments of said secondary winding of said first transformer and a drive winding; at least one primary winding in series with at least one of the following: and a secondary winding coupled to the tuned oscillator;
A tuned oscillator ballast circuit in which the charge storage and selective isolation and supply circuit couples the load energization circuit to the DC potential supply circuit, wherein the load energization circuit and the charge storage and selective isolation and supply circuit Tuned oscillation characterized in that it includes transient current compensation means 121, 153 coupled and shunting said rectifier circuit to supply initial surge energy to said charge storage and selective isolation and supply circuit for initial charging. Shape ballast circuit.

14. Tuned oscillation according to claim 13, wherein said transient current compensation means is in the form of a diode shunting said rectifier circuit and coupling said load energizing circuit to said charge storage and selective isolation and supply circuit. Shape ballast circuit.

15 said transient current compensation means is in the form of a diode connected to said primary winding of said first transformer of said load energizing circuit and to said charge storage and selective isolation and supply circuit; Claim 13 shunting the rectifier circuit
Tuned oscillation type ballast circuit described in .

16 said charge storage and selective isolation and supply circuit is in the form of a diode and capacitor coupled in series and shunting said DC potential supply circuit, and said transient current compensation means is in the form of a diode and capacitor coupled in series and shunting said DC potential supply circuit; 14. The tunable oscillator ballast circuit of claim 13, wherein the oscillating ballast circuit is coupled to the load energizing circuit.

[Detailed description of the invention]

The present invention relates to a high efficiency ballast circuit suitable for a fluorescent lamp load, and more particularly to a tuned oscillation type ballast circuit that uses feedback from a load circuit to drive an oscillator.

Currently, the fluorescent lamp lighting device commonly used is an autotransformer type ballast, but this type of device is known to have the disadvantage that it is heavier and difficult to handle than an electronic type ballast. Additionally, devices of this type are known to be relatively inefficient, generate unwanted heat and waste energy, and operate at frequencies within the audio range (60 Hz).

Other common ballast circuits use flip-flop oscillators and saturated core transformers, but the saturation characteristics of the core are used to limit the current, which is difficult to predict and control accurately. . Therefore, this type of device lacks reliability.

Another type of ballast circuit is a sine wave oscillator circuit which includes circuitry to compensate for the "storage time" of the transistors of the oscillator circuit. Although this circuit has improved capabilities compared to previously known devices, it suffers from the disadvantage that improved efficiency cannot be achieved without a disproportionate increase in cost.

Other types of ballast circuits have storage capabilities in which the pulsating DC potential (voltage) supplied to the tuned oscillator is converted to provide a substantially constant DC potential to the lamp load. However, this circuit has been found to have a drawback in response to sudden changes in load.
There has been a strong demand for protective measures to eliminate this problem.

It is therefore an object of the present invention to eliminate, or at least significantly reduce, the aforementioned disadvantages and to provide a ballast circuit with improved self-protection capabilities.
Another object of the present invention is to improve the reliability of the ballast circuit against lamp loads and to provide a ballast circuit with compensatory protection during load removal and initial start-up.

Embodiments of the present invention will be described in detail below with reference to the drawings.

The high efficiency tuned oscillator ballast circuit of FIG. 1 includes an alternating current potential source (hereinafter referred to as an alternating current power supply) 3 coupled to a pulsating direct current potential source (hereinafter referred to as a direct current voltage source) 7 through a power supply conditioning circuit 5. A tuned oscillator 9 functioning as a high frequency inverter is coupled to a DC voltage source 7 and a load energizing circuit 11 , which in turn is coupled to a load 13 . The rectifier circuit 15 is coupled to the load energizing circuit 11 and is a circuit for selectively isolating and supplying charge storage and accumulated charge that shunts the DC voltage source 7 (hereinafter referred to as a charge storage and selective isolation and supply circuit). (call) is connected to 17. A drive circuit 19 is coupled to the load energizing circuit 11 and the tuned oscillator 9 and applies a drive voltage to the tuned oscillator 9.

Specifically, the power supply regulating circuit 5 includes a transient state suppressor 20 that shunts the AC power supply 3, a switch 21 that couples one side of the AC power supply 3 to the DC voltage source 7, a fuse 23, and a first inductor 2
Contains 5. The other side of the AC power supply 3 is coupled to the DC voltage source 7 via a second inductor 27 . The first capacitor 29 is interposed between the first inductor 25 and ground, and the second capacitor 31 is interposed between the second inductor 27 and ground. Further, the capacitor 33 shunts the DC voltage source 7, and is used to improve the power factor in conjunction with the power supply adjustment circuit 5.

The DC voltage source 7 has first and second diodes 35 and 37 coupled to the connection point between the first inductor 25 and the capacitor 29 of the power adjustment circuit 5, and also has a second
It is composed of a diode bridge in which third and fourth diodes 39 and 41 are coupled to the connection point between the inductor 27 and the capacitor 31. Therefore, the DC voltage source 7 is coupled to the AC power supply 3 via the power supply regulating circuit 5 . The tuned oscillator 9 includes first and second transistors 43 connected in series, which shunt the DC voltage source 7;
45. Diode 47 and capacitor 4
A bias circuit formed by 9 parallel connections is connected to the base of the first transistor 43 and the collector via the resistor 51. This first transistor 4
The switching auxiliary circuit No. 3 includes a resistor 53 and a diode 55 connected to the emitter and base.
The second bias circuit includes a second transistor 45
A diode 57 and a capacitor 59 are connected in parallel to the base and collector of the capacitor 57 via a resistor 61. The switching auxiliary circuit of the second transistor 45 includes a resistor 63 and a diode 65 connected to the emitter and base.

The load energizing circuit 11 includes a transformer 67 having a primary winding 69, which is connected to the emitter of the first transistor 43 of the tuned oscillator 9 through a series connection circuit of an inductor 71 and a capacitor 73. One side is connected to the connection point with the collector of the transistor 45, and the other side is connected to the rectifier circuit 15. The transformer 67 has the following three secondary windings 75, 81 and 87. The first secondary winding 75 is a series connection of a drive winding 77 and a filament winding 79, and the second secondary winding 81 is a series connection of a drive winding 83 and a filament winding 85. ,
The third secondary winding 87 is a series connection of a drive winding 89 and a filament winding 91. The first, second and third secondary windings 75, 81 and 87 are respectively connected to the first, second and third primary windings 93, 95 and 97 of the transformer 99 of the drive circuit 19, and It is also coupled to load circuit 13 . A ground return path for the voltage of the load circuit 13 and the starting aid is formed by a resistor 96 and a capacitor 98 connected in parallel.

The first, second and third primary windings 93, 95, 97 of the transformer 99 of the drive circuit 19 are
are coupled to secondary windings 101 and 103 of the tuned oscillator 9, which are coupled to the first and second transistors 43 and 45, respectively, of the tuned oscillator 9 to provide its drive voltage. Furthermore, the load circuit 13 is comprised of two fluorescent lamps 105 and 107 coupled to the three secondary windings 75, 81, 87 of the transformer 67, respectively.

Rectifier circuit 15 is also coupled to primary winding 69 of transformer 67 of energizing circuit 11 . This rectifier circuit 15
comprises a variable inductive winding 109 connecting the primary winding 69 in series to a potential reference level and a capacitor 111 coupling this winding 109 to the connection point of the series connection of first and second diodes 113, 115. I can do it.

Diode 115 of rectifier circuit 15 is connected to capacitor 117 and diode 1 of charge storage and selective isolation and supply circuit 17 which shunts DC voltage source 7.
It is coupled to 19 connection points. Furthermore, a transient (current) protector formed by a Zener diode 121 is provided to the junction of the capacitor 117 and the diode 119 of the charge storage and selective isolation and supply circuit 17 and to the diode 115 of the rectifier circuit 15 and to the DC voltage source 7. Ru.

Another specific example of the tuned oscillation type ballast circuit of FIG. 1 is shown in FIG. Substantially the same parts except for the diode 121 are designated by the same numbers. In this other embodiment of FIG.
A transformer 123 is included having a primary winding 125 coupled to the junction of transistors 43 and 45 of tuned oscillator 9 via a series connection of 1 and capacitor 73. The primary winding 125 is connected to circuit ground via the adjustable inductor 109 of the rectifier circuit 15.

The transformer 123 includes the following three secondary windings, the first secondary winding 127 is a series connection of a drive winding 129 and a filament winding 131, and the second secondary winding is a series connection of a drive winding 129 and a filament winding 131. 133 is a series connection of a drive winding 135 and a filament winding 137, and a third secondary winding 139 is a series connection of a drive winding 141 and a filament winding 143. However, oscillator drive circuit 19 comprises a transformer having a single primary winding 147 connected in series with the second secondary winding of transformer 123. Furthermore, its primary winding 147 is connected to a pair of transistors 43 of the tuned oscillator 9.
and 45, respectively.

The transient protection in the circuit of FIG. coupled to circuit 17;

Regarding the operation in the embodiment of FIG.
Both filters are useful. Transient suppressor 20, which is a suppressor of transient phenomena, clips signals during undesired transients.
It also acts as a filter for clipped but unwanted signals. Furthermore, these signals are filtered by one of the first or second inductors 25,27. In addition, the first and second inductors 2
5 and 27 work together with capacitors 29 and 31 to serve as a filter for suppressing the RFI signal appearing in the AC power supply 3.

Next, the operation of the tuned oscillation type ballast circuit according to the present invention having the above configuration will be explained.

When the switch 21 is turned on, the alternating current potential (voltage) from the alternating current power supply 3 is applied to the power supply regulating circuit 5, and undesired transient phenomena and RFI signals are removed, resulting in a relatively pure alternating current potential (voltage). It is supplied to a DC voltage source 7. In this DC voltage source 7, the AC potential is voltage doubled and rectified, for example, when an AC input is
If it is 60Hz, it will be converted to a pulsating DC potential (voltage) of 120Hz. This pulsating DC voltage is smoothed by a capacitor 33 and then supplied to a tuned oscillator 9 which functions as a high frequency inverter. Tuned oscillator 9
When a DC voltage is applied to the resistor 51, a current flows through the base-emitter junction of the transistor 43, the resistor 61, and the base-emitter junction of the transistor 45, and one of the transistors turns on first. This initial turn-on of one transistor couples the series resonant circuit including capacitor 73, inductor 71, and primary winding 69 of transformer 67 (FIG. 1) or primary winding 125 of transformer 127 (FIG. 2) to the transistor; As a result, oscillation occurs. In this embodiment, this series resonant circuit has a resonant frequency of approximately 20 KHz. Since this series resonant circuit provides a low impedance path for the flowing current, the current flowing in the primary winding 69 increases and the current flowing in the secondary windings 75, 81 and 87, the filament windings 79, 85 and 91, and The current flowing through the load driving windings 77, 83 and 89 increases.

Importantly, the oscillator drive circuit 19 has its transformer 99 primary windings 93, 95, 97 connected in series with the transformer secondary windings 75, 81, 87 of the load energizing circuit 11; This means that the current flowing through the primary windings 93, 95, and 97 of 99 also increases. The drive current of the oscillator increases because the current in the secondary windings 101, 103 of the transformer 99 increases, and the drive currents of the first and second transistors 43, 45 correspondingly increase. As a result, the current flowing through the transformer primary winding 69 of the load energizing circuit 11 further increases, and the current increases rapidly in the same manner, resulting in lamp loads 105, 1
The voltage across 07 increases rapidly. The lamp loads 105, 107 are thus lit, and the voltage across the loads remains at a voltage sufficient to maintain the lamps lit.

On the other hand, if the pulsating DC voltage drops below a predetermined reference level due to a sudden increase in current, the rectifier circuit 1
Since the pulsating DC voltage rectified by 5 has a higher potential, this voltage is supplied to the DC voltage source 7, and therefore the DC voltage supplied to the oscillator 9 does not fall below a predetermined reference level. , resulting in a nearly constant DC voltage. Specifically, the variable inductive winding 109, or inductor, is connected to the load energizing circuit 11.
The transformer is connected in series with the primary winding 69 of the transformer, and as the current flowing through the primary winding 69 increases, the current increases accordingly. The current flowing through this inductor is rectified, in this embodiment voltage doubled, and fed to a capacitor 117 of charge storage and selective isolation and supply circuit 17 for storage. When the voltage of the DC voltage source 7 drops below the charge accumulated in the capacitor 117, the isolation diode 119 becomes conductive, so that the charge accumulated in the capacitor 117 becomes lower than the charge accumulated in the DC voltage source 7.
This prevents the voltage from dropping. The voltage of the DC voltage source 7 drops when the current flowing through the load energizing circuit 11 increases. At this time, the current flowing through the inductor 109 also increases, so the rectified voltage of the rectifier circuit 15 increases, and the voltage of the DC voltage source 7 decreases. 7
will be supplied to The DC voltage applied and used to the tuned oscillator 9 and the energizing circuit is thus at a substantially constant potential, and undesirable strobe effects in the load circuit are eliminated. In addition, the isolation diode 119 blocks energy that has a deleterious effect on the power factor, such as that found in the rectifier circuit 15 and the DC voltage source 7.

The reason why the rectifier circuit 15 is a voltage doubler rectifier circuit is based on the circuit design to obtain a DC voltage higher than a predetermined reference voltage level when the current increases.
Of course, other rectifier circuits may be used that achieve the intended purpose.

In addition, it has been known for some time that the excitation or initial start-up of the circuit involves transient currents that may be harmful or even destructive to the transistors 43 and 45 of the tuned oscillator 9. This undesired initial current transient turns on transistors 43 and 45 simultaneously, creating a so-called "totem pole" effect in which the power supply is essentially shorted by transistors 43 and 45 and excessive current flows through transistors 43 and 45. There is a good chance that it will. However, in this embodiment, the Zener diode 121 is used as a transient state protector against such a transient current between the connection point of the first and third diodes 35 and 37 of the DC voltage source 7 and the charging capacitor 117 of the circuit 17. During excitation or initial start-up of the circuit, the series circuit of the Zener diode 121 and the capacitor 117 shunts the DC voltage source 7 until the capacitor 117 is charged to a predetermined voltage value, thus The unwanted initial transient current flows through Zener diode 121 to capacitor 117 and no "totem pole" effect occurs. That is, the undesired initial transient current is absorbed during the initial charging of the charging capacitor 117,
No "totem pole" effect occurs. Once the charging capacitor is fully charged, the transient protector, eg, Zener diode 121, is no longer necessary for actual circuit operation.

The inductor 109 of the rectifier circuit 15 is adjustable not only as a filter yoke but also to enable control of the output voltage applied to the load circuit 13, and the inductor 71 eliminates undesirable spike voltages and transient voltages. It is noteworthy that it acts as a smoothing surface. Thus, the adjustable inductor 109 could also be used for so-called dimming control of the load circuit 13 when the load is a lamp. Furthermore, transistors 43 and 4
Each of numerals 5 and 5 has a switching auxiliary circuit consisting of a series connection of a resistor and a diode, that is, a resistor 53 and a diode 55 for the transistor 43, and a resistor 63 and a diode 65 for the transistor 45. Also, a ground return path in the form of a parallel connection of a resistor 96 and a capacitor 98 leading to the load circuit 3 assists in the initial current flow into the load circuit.

In the embodiment shown in FIG. 2, transformer 1 of the load energizing circuit
2 is the first, second and third secondary winding 127, 13
Contains 3,139. However, the second secondary winding 13
3 drive winding 135 and filament winding 13
The series connection of 7 is connected in series to a single primary winding 147 of the transformer 145 of the oscillator drive circuit 19. This single primary winding 147 is alternately utilized by secondary windings 149 and 151 associated with transistors 43 and 45, respectively, to provide base drive voltages.

Furthermore, the transient state protector may include, for example, a diode 153 connected across the rectifier circuit 15.
is formed. The initial transient voltage that causes a "totem pole" current in the first and second transistors 43 and 45 is then applied to capacitor 73, inductor 71, primary winding 125, and diode to charge capacitor 117, which is a power storage device. 1
53 is bypassed via a low impedance path through the resonant circuit. Once the charging capacitor 117 is charged, the connection point between the diode 153 and the inductor 109 becomes a negative potential, and the diode 153 is reverse biased. As a result, once the initial charging of charging capacitor 117 is completed, diode 153 or the transient protector becomes a virtually inactive component. It has also been found that relatively inexpensive diodes can be used as transient protectors in preference to the relatively expensive Zener diodes shown in FIG.

As described above, a unique tuned oscillation type ballast circuit is provided which has the function of using the current flowing through the filament circuit of the load as the drive current of the tuned oscillator. In this scheme, removal of the load, such as removal of the lamp, greatly reduced the drive current of the tuned oscillator. The oscillator is thus protected from harmful high currents due to failure or removal of the load.

In addition, a circuit that uses one filament winding connected in series with one drive winding to drive the oscillator associated with the lamp load of two lamps or to drive the base of the oscillator is a circuit that uses one filament winding connected in series with one drive winding. is presented for circuits that utilize . Clearly, the use of a single winding reduces component cost as well as circuit complexity.

Furthermore, the transient protector actually eliminates the serious problem of damage to transistor components due to initial transient currents. Furthermore, a circuit that increases the protection capability of the protection circuit has been achieved using relatively inexpensive components.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing one embodiment of a ballast circuit according to the present invention, and FIG. 2 is an electric circuit diagram showing another embodiment of the present invention. 3: AC potential source, 7: Pulsating DC potential source, 9: Tuned oscillation circuit, 11: Load energizing circuit, 13: Load circuit, 15: Rectifier circuit, 17: Charge accumulation and selective isolation of accumulated charges, Supply circuit, 19: Drive circuit.

Claims (1)

[Scope of Claims] 1. AC potential source 3; DC potential supply means 7 coupled to the AC potential source and supplying a pulsating DC potential; and a high frequency electrical potential supply means 7 coupled to the DC potential supply means and supplying a high frequency output potential. output potential supply means 9; load energization means 11 coupled to the high frequency output potential supply means for energizing the load circuit 13; a rectifying means 15 coupled to the load energizing means and rectifying the high frequency output potential; a rectifying means 15 coupled to the rectifying means and storing energy;
an energy storage device for selectively isolating the stored energy and selectively supplying the DC potential supply means to supply stored energy when the pulsating DC potential falls below a predetermined DC potential reference level;