KR100672038B1 - Electronic ballast having a dimming-controlling part of which the lamp current is maintained uniformly by feedback-controlling with the detected current - Google Patents

Abstract

An electronic ballast having a dimming-controlling function to maintain a constant current by comparison of a detected current is provided to maintain constant intensity of illumination regardless of variation of temperature of a lamp or surrounding temperature or operation stop of the ballast, by providing an initial dimming control circuit helping lamp discharge in case of ON/OFF of an input voltage. An electronic ballast has a voltage input part(1), a bridge rectification part(2) rectifying a voltage of the voltage input part, an inverter part(5) driving a lamp(14) by inverting a rectified voltage into a high frequency signal, a frequency oscillation part(4) applying an oscillation frequency to the inverter part and a resonant part(8) forming a resonant circuit with the lamp. A current sensing part(7) senses a current of the inverter part or the lamp. A current comparison part(9) outputs an output value of comparing a voltage of an input terminal with a reference voltage of another input terminal, as a dimming controlling signal. A frequency control part(6) controls the oscillation frequency of the frequency oscillation part according to the dimming controlling signal.

Description

ELECTROLNIC BALLAST HAVING A DIMMING-CONTROLLING PART OF WHICH THE LAMP CURRENT IS MAINTAINED UNIFORMLY BY FEEDBACK-CONTROLLING WITH THE DETECTED CURRENT}

1 is a block diagram of an illumination control electronic ballast according to the present invention;

2 is a detailed circuit diagram of a first embodiment of the light control electronic ballast according to the present invention;

3A is an operation characteristic diagram of the initial dimming control unit of the embodiment shown in FIG. 2;

Fig. 3B is a detailed circuit diagram of the initial dimming control unit of the ballast of the second embodiment of the present invention.

3C is an operation characteristic diagram of the initial dimming controller of the embodiment shown in FIG. 3B.

4A is a detailed circuit diagram of a current sensing unit of a ballast of a third embodiment of the present invention.

4b is an operational characteristic diagram of a current sensing unit according to the present invention;

Fig. 5 is a detailed circuit diagram of a dimming control unit of the ballast of the fourth embodiment of the present invention.

Fig. 6 is a detailed circuit diagram of a dimming control unit of the ballast of the fifth embodiment of the present invention.

Fig. 7 is a detailed circuit diagram of a dimming control unit of the ballast of the sixth embodiment of the present invention.

<Description of the symbols for the main parts of the drawings>

1. Power input 2. Bridge rectifier

3. Constant Power Supply (PFC) 4. Frequency Oscillator

5. Inverter section 6. Frequency control section

7. Current sensing unit 8. Resonant circuit unit

9. Current comparator 10. Initial dimming controller

11. Dimming voltage generator 12. External controller

13. DC voltage generator 14. Lamp

The present invention relates to an electronic ballast having a dimming control function, and more particularly to an electronic ballast having a dimming control function capable of maintaining a constant current by comparison of the detected current.

In particular, the electronic ballast having the dimming control function according to the present invention maintains the constant current of the inverter and the lamp current by detecting the output current and performing feedback control in comparison with the reference voltage, so that the brightness of the lamp is kept constant. The present invention relates to an electronic ballast having a possible dimming control function. Furthermore, a dimming control electronic ballast capable of uniformly maintaining indoor illumination by selecting a desired illuminance with a selected function (step 4), wherein the first stage is 100% illuminance and the second stage is The electronic stage 4 has the advantage of selecting the illumination of the ballast for each location by using 80% ~ 70%, 50% ~ 40% for the third stage, and 30% ~ 15% for the fourth stage. It relates to a ballast for dimming control electronic fluorescent lamps.

Electronic ballasts contain a starting semiconductor element in the ballast, which preheats the electrode with its switching action or electrode heating winding and starts the lamp by the semiconductor switching action, while the lamp is heated by the lamp current and the electrode heating winding during lighting. It is a ballast used for the circuit method

Conventional dimming control electronic ballast shows the difference in illuminance when ballasts are installed in several places even for the same product, and it is difficult to produce a constant product according to the difference of lamp temperature or ambient temperature every time it is produced. It has a problem to manage the temperature and to supplement the set power according to the ambient temperature.When the power is turned on / off at too low illuminance setting in the illuminance setting process, the ballast does not operate. In many cases, the ballast may be turned off or fail.

In addition, the group dimming control has a problem that the phase of the power supply line is changed with each other causing a failure of the ballast.

Accordingly, the present invention is to detect the current at the inverter and the lamp output stage, and to perform the dimming control to a value comparing the detected current with the reference value, so that the problems with the conventional dimming control electronic ballast as described above, Dimming control not only makes it possible to keep the brightness of the lamp constant, but also controls the ballast to start at 100% brightness at the beginning, and sets the desired level to several levels after startup. It relates to an electronic ballast having a function.

In other words, the inverter and lamp current are detected to form a comparison voltage, and the comparison circuit calculates the reference voltage and the comparison voltage to keep the inverter and lamp current constant, and lamp discharges when the input voltage is ON / OFF at the minimum dimming level. By developing an initial dimming control circuit to assist the system, the illuminance stops operating due to the lack of minimum dimming level, the unlit state and the lamp current due to cold winter temperature, or the illuminance is maintained even if the lamp temperature or the ambient temperature difference occurs. The present invention provides a dimming control electronic ballast circuit that can be maintained at a high level.

In addition, the dimming control unit was operated by forming a separate power source from the power line so as to separate the power control circuits of the dimming control unit and the ballast and control several ballasts in groups.

Further objects and effects of the present invention will become more apparent from the following detailed description of the invention described with reference to the accompanying drawings.

In order to achieve the above object, the electronic ballast having a dimming control function capable of maintaining a constant current by comparison of the detection current according to the present invention, the power input unit 1, the bridge rectifier 2 for rectifying the power supply of the power input unit The inverter rectifies the voltage rectified by the bridge rectifier into a high frequency signal to drive the lamp 14, generates an oscillation frequency for adjusting the brightness of the lamp, and applies it to the inverter 5. An electronic ballast having a dimming control function, comprising a frequency oscillation unit 4 and a resonator unit 8 forming a resonant circuit with the lamp, for sensing current of the inverter unit 5 or the lamp 14. A current sensing unit 7; 7 '; A current that receives a voltage value corresponding to the current sensed by the current sensing unit as the voltage V1 of one input terminal and outputs an output value V3 compared with the reference voltage V2 of the other input terminal as a dimming control signal. Comparison section 9; And a frequency controller (6) coupled to the frequency oscillator (4) for controlling the oscillation frequency of the frequency oscillator (4) according to the dimming control signal from the current comparator (9). Characterized in that it comprises a.

Preferably, the current sensing unit 7; 7 'is inductively coupled to one side of the inverter unit 5 or the lamp 14 by a transformer T4 to detect current,

A current is detected by detecting a voltage of the detection resistor by connecting a detection resistor R44 by tapping one side of the inverter section 5 or the lamp 14.

The dimming voltage generator 11 may further include a dimming voltage generator 11 outputting at least two or more reference voltages V2 by the external controller 12 or by preset dimming steps. The other input terminal of the unit 9 is connected to the dimming voltage generator 11, the variable output value of the dimming voltage generator is input to the reference voltage (V2) of the other input terminal,

More preferably, the dimming voltage generator 11 applies the output of the DIP switch SW DIP-3 for outputting at least two different preset reference voltage values to the current comparator 9 of the next stage. Characterized in that,

Most preferably, further comprising an initial dimming control unit 10, the other input terminal of the current comparison unit 9 is connected to the initial dimming control unit 10, the initial dimming control unit 10 at the start of ballast The ballast is started brightly by the reference voltage by the output of), and after a predetermined time elapses, the ballast oscillates in a preset dimming step.

As a result, the electronic ballast having a dimming control function according to the present invention includes a bridge rectifier circuit for generating an AC input and a pulse current, and a current of the input (AC) generated during the conversion of the pulse current to a DC (direct current) voltage. PFC (Power Factor Correction) circuit and PFC (Power Factor Correction) circuit that controls current harmonics according to the phase difference of voltage and keeps the output power constant even if the input voltage changes by ± 20%. Inverter for high frequency switching by receiving operating voltage, frequency oscillator for stably controlling lamp current by adjusting switching frequency of inverter, frequency controller for controlling oscillation frequency of frequency oscillator by processing signal of dimming controller And an inverter and lamp current sensing unit for detecting a lamp current to maintain a constant lamp current, and an inverter and a lamp current sensing unit. Inverter current comparator for comparing control current to generate control signal of frequency controller, dimming voltage generator for four-stage setting, initial dimming controller for smoothly maintaining dimming during initial power ON / OFF, and external controller It is characterized by.

Best Mode for Carrying Out the Invention The best mode of the present invention will be described in detail with reference to the accompanying drawings.

1 is a block diagram of a dimming control electronic ballast according to the present invention, and FIG. 2 is a detailed circuit diagram of a first embodiment of the dimming control electronic ballast according to the present invention.

First, the A.C input voltage outputs a pulsation voltage from the bridge rectifier circuit 2 including the diodes D1 to D4 and the capacitors C2 and C3 through the fuse FUSE and the line filter L1. The pulsed voltage, which is the output of the bridge rectifier, is connected to the resistors R1 to R14, the capacitors C4 to C8, the diodes D5, D6 and D7, the first IC IC1, the FET Q1, and the boost transformer T1. It is applied to the PFC (Power Factor Correction) circuit which is comprised.

The PFC circuit operates the FET Q1 by adjusting a reference pulse width corresponding to the height of the pulse voltage by breathing the pulse voltage of the input voltage from the resistors R1 to R3 and the capacitor C4.

The operation of the FET Q1 generates a high induced voltage in the boost transformer T1. The induced voltage of the boost transformer T1 is VL = -L · (di / dt) (V). The induced voltage VL of the boost transformer is charged to the capacitors C7 and C8 via the diode D7.

The charging voltages of the capacitors C7 and C8 are breathed by the resistors R10, R11, and R12, and calculated with a comparison voltage (for example, 2.5V) inside the first IC to pulse the gate of the FET Q1. After adjustment, the capacitors C7 and C8 are charged again.

At this time, when the charging voltage of the capacitors C7 and C8 is higher than the predetermined set voltage, the gate pulse width of the FET Q1 is reduced, and when the charging voltage is low, the pulse voltage is widened to maintain the charging voltage constant.

In addition, the pulse voltage is applied to the initial operation voltage to the second IC (IC2) that is the IC of the frequency generator (4).

When an initial voltage is applied to the second IC IC2, a frequency is generated by the resistors R15, R16, and R17 and the capacitors C10 and C11. The oscillation frequency of the frequency generator is derived from the transformer T2 and applies an operating frequency to the inverter unit 5.

That is, according to the induction frequency of the transformer T2, the inverter unit including the diodes D8 to D13, the resistors R18 and R19, and the FETs Q2 and Q3 performs a high speed switching operation.

In addition, the high frequency high voltage generated by the high speed switching operation of the inverter unit 5 is waveform-shaped by a square wave in the resonator unit consisting of the resonant transformer T4 and the capacitors C13, C14, and C15 via the capacitor C12. Discharge.

In addition, the high frequency high voltage generated by the operation of the inverter unit generates a power supply voltage of the frequency oscillator in the resistor R39, the capacitor C21, and the diodes D22 and D23 to smoothly maintain the operation of the frequency oscillator.

On the other hand, the secondary winding of the resonant transformer T4 generates a DC voltage Vcc by the DC voltage generator 13 including the resistors R24 and R28, the diode D14, and the capacitor C16 by receiving the resonance current. In this way, operating power is applied to the dimming voltage generator 11, the inverter current comparator 9, and the initial dimming controller 10.

Therefore, the operation power source Vcc of the dimming voltage generator 11, the inverter current comparator 9 and the initial dimming controller 10 is connected to the main circuits 1, 2, 3, 4, 5, 6, 14 of the ballast. Since it is separated from the power supply circuit of the power supply circuit and the inverter unit 5 and the resonator unit 8, it is possible to solve the problem of the prior art that the phase of the power supply line is changed with each other during group dimming control, resulting in a failure of the ballast. By separating the dimming control unit and the power supply circuit of the ballast, it is possible to control several ballasts in groups. Furthermore, as will be described later, the dimming control circuits 9, 10, 11, 12, 13 are also connected to the frequency control section 6 through the photocoupler (O.C1), so that the ballast main circuit section according to the application of the control signal In addition, the influence of the can be minimized.

On the other hand, in order to detect and feedback the resonant current, current detection is required. The inverter and the lamp current are detected by the third transformer T3, which is another transformer, so that the resistors R25, R26, R27, capacitor C17, Inverter current comparison section 8 composed of a fourth IC (IC4), resistor R31, and capacitor C18 as a second comparator by forming a control voltage in current sensing section 7 composed of diode D15. Is applied via a resistor R29. More specifically, the output terminal of the current sensing unit is connected to the negative input terminal of the second comparator IC4 through the resistor R41.

Thus, when the resonant current of the resonator 8 is high, the inverter current comparator 9 increases the negative input voltage V1 of the second comparator IC2, thereby lowering the output of the second comparator IC2. Low to stop the operation of the photocoupler (O. C1) via the diode (D16) and the resistor (R30), thereby making the base voltage of the transistor (Q4) high (high), and thus the transistor (Q4). ) Will work. When the transistor Q4 operates, the resistors R15 and R39 become parallel resistors, so that the total resistance value is lowered and the frequency is increased. In addition, the increased oscillation frequency of the frequency oscillator 4 reduces the resonance current of the resonance circuit, so that the resonance current is kept constant. The above is briefly shown as follows.

Operation path 1

Resonant current high → IC4 output low → O.C1 off → Q4 turn on → Total resistance decrease → Frequency increase → Resonance current decrease

On the other hand, the other input (+) of the second comparator IC4 of the inverter current comparator 9 has resistors R36 and R34, a capacitor C20, a DIP switch SW DIP-3, and a diode D19. It is connected to the dimming voltage generator 11 consisting of, D20, D21.

The dimming voltage of this embodiment is, for example, composed of three different constant voltage sources, and is applied to the reference voltage V2 of the inverter current comparison unit 9 through the resistor R34.

Therefore, when the set dimming voltage V2 generated by the dimming voltage generator 11 is high, the reference voltage V2 of the second comparator IC4 becomes higher than the comparison voltage V1, and thus the second comparator IC2. ) Is made high, so that the operation is reversed to the 'operation path 1', and the inverter current and the lamp current are increased, resulting in a high illumination (see 'operation path 2'), On the contrary, when the dimming voltage V2 set generated by the dimming voltage generator 11 is low, the dimming voltage V11 operates as in the operation path 1, and thus the illumination intensity is low.

Operation path 2

Resonant current low → IC4 output high → O.C1 operation → Q4 off → Total resistance increase → Frequency decrease → Resonance current increase

Now, when the initial dimming control unit 10 is described in detail, it comprises a resistor (R33, R35), a capacitor (C19), and a third IC (IC3), which is a first comparator, and dimming the dimming voltage generator when the initial power is turned on. Maximize the voltage so that the circuit operates at 100%.

In detail, when the power is turned on, the positive input of the first comparator IC3 is inputted with the dimming voltage V5 of the dimming voltage generator 11, and the negative input is connected with the resistor R33. The voltage divider R33 and R35 of the integrating circuit of the capacitor C19 and the voltage V4 of the connection point of the capacitor C19 are input.

Therefore, the integrating circuit of the resistor R33 and the capacitor C19 gradually charges the voltage by the integral constant. As such, the negative input V4 of the first comparator IC3 is lower than the positive input V5 for a considerable time (for example, 20 seconds) so that the output of the first comparator IC3 is high. The high signal is input to the inverter current comparison section 9 via the diode D17. Therefore, since the positive input V2 of the second comparator IC4 of the inverter current comparator 9 is higher than the negative input V1, the output V3 of the second comparator IC4 is changed. Since it outputs high, the oscillation frequency of the frequency oscillator 4 is lowered, thereby maintaining 100% lamp power. In summary, it is as follows 'operation path 3'.

Operation path 3

Ballast turn-on → IC3 output high → IC4 output high → O.C1 operation → Q4 off → Total resistance increase → Frequency decrease → Resonance current increase

However, the negative input of the first comparator IC3 of the initial dimming controller 10 becomes higher than the positive input after a predetermined time (for example, 20 seconds), and the first comparator IC3 is low. ), So that the dimming circuit of the current comparator 9 is no longer affected.

Therefore, in the initial state when the power is initially turned on, the lamp current is maintained at 100% for a certain time, and after a certain time, the lamp output is maintained at a predetermined state according to the DIP switch.

However, the resistor R37, the second photocoupler (O.C2) and the diode D18 of the dimming voltage generator 11 are connected to the external controller 12 and operate according to a signal of the external controller. For example, when the signal of the external controller 12 is input to high, the positive input of the second comparator IC4 of the inverter current comparator 9 is made higher than the negative input of the second comparator ( Since IC4) is output high, the lamp current is maintained at 100% as shown in the following 'Operation Path 4'.

Operation path 4

External controller signal high → IC4 output high → O.C1 operation → Q4 off → Total resistance increase → Frequency decrease → Resonance current increase

When this function is installed in the office or other places (corridor, stairs), the lamp current is maintained at 100% if there is a person inside, and the lamp output is supplied to the DIP switch if it does not exist, such as when a person is out. Therefore, the illumination is maintained in a preselected state.

Like the circuit of the present invention, the external controller 12, the dimming controllers 7, 9, 10, 11, 13 and the ballast circuits 1, 2, 3, 4, 5, 6, 8, 14 are insulated transformer ( T3, T4) or photocouplers (O.C1, O.C2) isolate the power lines between circuits, and even if a lot of ballasts are dimmed, the phases of the power lines do not cross each other. The ballast will operate stably.

The operation of the electronic ballast of the present invention will be described below with reference to FIGS. 3A to 7.

3A is an operation characteristic diagram of the initial dimming control unit 10 of the embodiment shown in FIG. 2, FIG. 3B is a detailed circuit diagram of the initial dimming control unit 10 'of the ballast of the second embodiment of the present invention, and FIG. FIG. 3B is an operation characteristic diagram of the initial dimming control unit 10 'of the second embodiment shown in FIG.

As shown in the operating characteristic diagram of FIG. 3A, when the power supply of the ballast is turned ON, since the charging voltage V4 of the integrating circuit by the resistor R33 and the capacitor C19 is still a low voltage, Since the negative input of the first comparator IC3 of the dimming controller 10 is low, the outputs of both the first comparator IC3 and the second comparator IC4 of the inverter current comparator 9 are both high. It becomes (High), and since the oscillation frequency is low, the lamp current is maintained at 100%.

However, after a predetermined time to (for example, 20 seconds), since the charging voltage V4 of the integrating circuits R33 and C19 rises to a high voltage, the (-) of the first comparator IC3 is negative. Since the input becomes high, the output of the first comparator IC3 becomes low and the dimming control unit does not affect the input terminal of the second comparator IC4 of the inverter current comparator 9. Affected by the generator 11, it maintains the selected illuminance according to the setting of the DIP switch. Therefore, in general, since it is set to a lower illuminance, the oscillation frequency of the frequency oscillator 4 becomes higher after time to, and the final lamp current is lowered.

3B shows an initial dimming controller 10 'of another embodiment of the present invention. In the second embodiment, a PNP transistor Q4 is used instead of the first comparator IC3. The base voltage of the transistor Q4 is connected to the connection point of the integrating circuit by the resistor R43 and the capacitor C19,

At initial startup of the ballast, the transistor is turned on because the base voltage of the transistor Q4 is a low voltage, and the positive input of the second comparator IC4 of the inverter current comparator 9 is set to High. The output of the IC4 also becomes high, and eventually the lamp current is maintained at 100%.

However, as can be seen from the characteristic diagram of Fig. 3C, the initial dimming control using the transistor of the second embodiment is similarly oscillated with the output voltage of the transistor Q4 gradually dropping over time at the 100% output at the initial startup. Frequency also gradually increases in frequency, resulting in a slow drop in illumination. In this respect, the first embodiment using the OP AMP as a comparator and the second embodiment using the transistor Q4 are different.

In addition, after a predetermined time (to), the output voltage of the transistor Q4 drops below the zener voltage, so that the transistor Q4 is turned off and does not affect the input terminal of the second comparator IC4 of the inverter current comparator 9. Since the dimming controller is affected by the dimming voltage generator 11, the dimming control unit maintains the selected illuminance according to the setting of the DIP switch.

The operation of the current sensing unit 7 of the present invention will now be described with reference to FIGS. 4A and 4B.

4A is a detailed circuit diagram of the current sensing unit of the ballast of the third embodiment of the present invention, and FIG. 4B is an operation characteristic diagram of the current sensing unit according to the present invention.

As shown in the operation characteristic diagram of FIG. 4B, when it is assumed that the voltage V2 of the positive input terminal of the second comparator IC4 of the inverter current comparator 9 is constant (see FIG. 4B (b)). When the voltage V1 at the negative input terminal of the second comparator IC4 due to the inverter and the lamp current is low (see (a) of FIG. 4B), the output V3 of the second comparator IC4 is Goes high; conversely, when V1 is high, V3 goes low.

On the other hand, as shown in FIG. 4A, instead of the transformer T of the first embodiment of FIG. 2, the resistor R44 is used in the current sensing unit 7 ′ of the third embodiment of the present invention. Can be.

The circuit of using the resistor R44 of the third embodiment is simpler than the circuit of using the transformer T3 of the first embodiment, but the disadvantage thereof is that the value of the resistor R44 becomes large in order to detect current. At% power, there is a loss of resistance and a thermal problem. However, the circuit design is easy.

As shown in the characteristic diagram of Fig. 4B, when the inverter current rises (Fig. 4B (a)), the output of IC4 is relatively decreased (Fig. 4B (c)). When the output of the IC4 decreases, the frequency generator increases the frequency to drop the lamp current to maintain stable operation.

Lastly, FIGS. 4 to 7 show circuits for the dimming control unit of the individual dimming control method, which is a modification of the present invention. 5 is a detailed circuit diagram of the dimming control unit of the ballast of the fourth embodiment of the present invention, FIG. 6 is a detailed circuit diagram of the dimming control unit of the ballast of the fifth embodiment of the present invention, and FIG. 7 is a detailed circuit diagram of the ballast of the sixth embodiment of the present invention. Detailed circuit diagram of the dimming control unit.

An individual dimming ballast having a dimming voltage generator 11 'using the variable resistor of FIG. 5 generates a dimming voltage individually for each ballast as the resistance value of the variable resistor VR1 is changed, thereby comparing the inverter current. The dimming control is individually performed for each ballast by changing the input terminal V2 of the positive terminal of the second comparator IC4 of the section 9.

An individual dimming ballast having a dimming voltage generator 11 "using the CDS of FIG. 6 generates a dimming voltage for each ballast individually by using a CDS, so that dimming of the ballast is performed according to the surrounding weather. Control method.

The individual dimming ballasts having the dimming voltage generator 11 "'using the phototransistor Q5 of FIG. 7 also generate dimming voltages individually for each ballast according to the photosensitivity of the phototransistors, respectively, and also individually dimming. This is the light control method of the ballast.

Although the present invention has been described above with reference to the embodiments shown in the accompanying drawings, the present invention is not limited thereto, and various modifications may be made within a range easily understood by those skilled in the art. Therefore, the limitation of the present invention should be limited only by the following claims.

As described above, according to the ballast according to the present invention, the brightness of the lamp is kept constant by detecting the current at the inverter and the lamp output stage, and performing dimming control to a value comparing the detected current with a reference value. In addition, it is also possible to perform dimming control of the ballast so as to start at 100% brightness at the beginning, and to set desired stages of various stages after the start-up. In addition, by developing an initial dimming control circuit that helps to discharge the lamp when the input voltage is ON / OFF at the minimum dimming level, the ballast does not operate due to the lack of minimum dimming level or unlit state and lamp current due to cold winter temperature. It is possible to maintain the constant illuminance even when the lamp is stopped or a difference between the temperature of the lamp and the ambient temperature occurs, and it is possible to control several ballasts in groups by separating the power control circuit of the light control unit and the ballast.

Claims (6)

The power input unit 1, the bridge rectifier 2 for rectifying the power of the power input unit, the inverter unit 5 for driving the lamp 14 by inverting the voltage rectified by the bridge rectifier into a high frequency signal, the lamp An electronics having a dimming control function, comprising a frequency oscillation unit 4 for generating an oscillation frequency for adjusting the brightness of the light source and applying it to the inverter unit 5, and a resonance unit 8 for forming a resonance circuit with the lamp. As a ballast, A current sensing unit (7; 7 ') for sensing current of the inverter unit (5) or the lamp (14); A current that receives a voltage value corresponding to the current sensed by the current sensing unit as the voltage V1 of one input terminal and outputs an output value V3 compared with the reference voltage V2 of the other input terminal as a dimming control signal. Comparison section 9; And A frequency controller (6) coupled to the frequency oscillator (4) and controlling the oscillation frequency of the frequency oscillator (4) according to the dimming control signal from the current comparator (9); Electronic ballast having a dimming control function capable of maintaining a constant current by comparison of the detection current comprising a. The method of claim 1, The current sensing unit 7; 7 ', An electronic ballast having a dimming control function, which is inductively coupled to one side of the inverter unit (5) or the lamp (14) by a transformer (T4) to detect a current. The method of claim 1, The current sensing unit 7 ', An electronic ballast having a dimming control function, characterized in that a current is detected by tapping one side of the inverter unit 5 or the lamp 14 and connecting a detection resistor R44 to detect a voltage of the detection resistor. . The method of claim 1, And a dimming voltage generator 11 outputting at least two or more reference voltages V2 by the external controller 12 or by preset dimming steps. The other input terminal of the current comparator 9 is connected to the dimming voltage generator 11 so that a variable output value of the dimming voltage generator is input to the reference voltage V2 of the other input terminal. Electronic ballast with dimming control function. The method of claim 4, wherein The dimming voltage generator 11, An electronic ballast having a dimming control function, characterized in that an output of a DIP switch (SW DIP-3) for outputting at least two preset different reference voltage values is applied to a current comparing section (9) of the next stage. The method according to any one of claims 1 to 5, Further includes an initial dimming control unit 10, The other input terminal of the current comparator 9 is connected to the initial dimming control unit 10, so that the ballast is started brightly by a reference voltage by the output of the initial dimming control unit 10 at the initial stage of ballast starting. An electronic ballast having a light control function, characterized in that after the predetermined time has elapsed, the ballast oscillates in a preset light control step.

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