KR100773815B1 - Electronic Ballast Control Circuit with Temperature Compensated Frequency Characteristics - Google Patents

Abstract

The present invention includes a reference voltage generator for generating a reference signal of a set level regardless of a change in ambient temperature; A switching unit which determines whether the entire circuit is operated; A temperature sensing unit for sensing an ambient temperature in the entire circuit and generating a temperature sensing signal corresponding thereto; An oscillator for generating an oscillation frequency to vary the variable current of the oscillator according to the sensed ambient temperature; In the electronic ballast circuit comprising a logic circuit and an output terminal connected to the oscillator, the temperature sensing unit is composed of a resistor (R ₂ , R ₃ , R ₄ ) and a transistor (Q ₂ ) which is a peripheral passive element, the resistance Temperature compensation is achieved by adjusting the ratio between the electronic ballasts having a temperature compensated frequency characteristic, characterized in that to sense the ambient temperature in the entire circuit and thereby to vary the current of the oscillator to maintain a constant frequency Circuit.

The present invention is equipped with a separate temperature sensing unit in the control circuit in order to prevent the frequency is reduced as the ambient temperature rises, the temperature compensation is made to maintain a constant frequency stably within the operating temperature at night, ultimately constant power consumption It is intended to extend the life of lighting fixtures such as light fixtures.

Description

Electronic stabilizer circuit of temperature-compensated frequency characteristics

1A and 1B are diagrams illustrating frequency characteristics and power consumption characteristics that appear as the ambient temperature increases in the electronic ballast according to the related art.

2 is a circuit diagram illustrating an embodiment of an electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention;

3A and 3B are diagrams illustrating characteristics of the reference voltage V _BG and the first to third currents I ₁ to I _{CT that} appear as the ambient temperature increases in the circuit diagram shown in FIG. 2.

4A and 4B illustrate a first embodiment of improved frequency characteristics and power consumption characteristics through an electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention;

5A and 5B illustrate a second embodiment of improved frequency characteristics and power consumption characteristics through an electronic ballast control circuit having temperature compensated frequency characteristics according to the present invention.

<Description of Major Symbols in Drawing>

10: reference current source generator

20: switching unit

60: temperature detection unit

The classification of fluorescent lamp ballasts is classified into magnetic circuit ballasts and electronic circuit ballasts by the principle of circuit operation. Magnetic circuit ballasts are used in the form of iron core chokes or transformers wound around copper cores and used as capacitors to improve power factor or noise protection, and to light the lamps properly. Since the magnetic circuit ballast uses a choke coil, a leakage transformer, and a large-capacity capacitor, a lot of power loss is generated by about 8 W or more due to heat generation by the iron core and copper wire of the ballast itself, other than the power consumed by light in a fluorescent lamp. In addition, the lamp is turned on with a commercial power supply of 60 Hz, causing flicker. When the power is bad and the ballast ages, the flicker may be worse when the ambient temperature is low or the humidity is high.

To compensate for this drawback, the electronic ballast rectifies AC 60Hz commercial power by using a semiconductor device to make DC (direct current), and converts it into high frequency of 25kHz ~ 50kHz in the inverter circuit so that it is stable through the output current limiting circuit. Lights up. Since the electronic ballast is turned on by a high frequency power source compared to the magnetic ballast, the luminous efficiency is improved by about 15%. Since the semiconductor element is used, self-heating in the choke coil can reduce the following losses by about 25%. 35% or more power savings can be achieved compared to the type ballast.

The conventional electronic ballast includes a semiconductor element in the ballast, and the electrode is preheated by the switching action or the electrode heating winding, the lamp is started by the semiconductor switching action, and the lamp is turned on by the lamp current and the electrode heating winding during the lighting. Electronic ballasts are systems that are likely to be used even at high temperatures, such as 125 ° C or higher.

However, if the frequency drops due to the oscillator temperature characteristic of the control circuit and the temperature characteristic of the external capacitor when the system's ambient temperature rises, the power consumption of the whole system increases.If the frequency drops, the brightness of the lamp gradually increases. The excessively brighter will also adversely affect the life of the lamp. This can be confirmed through a graph of frequency characteristics and power consumption characteristics that appear as the ambient temperature rises in the electronic ballast according to the related art shown in FIGS. 1A and 1B. In addition, when the power is turned on / off at too low illuminance setting during the illuminance setting process, the ballast does not operate, and even if it operates, the ballast cannot maintain the lamp current. In addition, even if the ballast is installed in several places, even if the same product, there is a difference in the illuminance, it is difficult to produce a constant product according to the difference of the lamp temperature or ambient temperature every time it is produced, There is a problem that must compensate for the set power according to the ambient temperature.

 The present invention has been devised to solve the above-mentioned problems, and in order to prevent the frequency from decreasing as the ambient temperature rises, a separate temperature sensing unit is mounted in the control circuit so that temperature compensation is made to maintain a constant frequency within the operating temperature range. By doing so, the power consumption is ultimately kept constant so as to extend the life of lighting fixtures such as electric lights. In addition, in order to improve the lighting characteristic at low temperature such as 0 ℃ or less, it is possible to surely turn on at a slightly lower frequency than the normal frequency, and to protect the system by continuously increasing the frequency in proportion to the temperature in the high temperature state.

The control circuit of the temperature compensated electronic ballast according to the present invention for achieving the above object comprises a reference voltage generator for generating a reference signal of a set level irrespective of changes in ambient temperature; A switching unit which determines whether the entire circuit is operated; A temperature sensing unit for sensing an ambient temperature in the entire circuit and generating a temperature sensing signal corresponding thereto; An oscillator for generating an oscillation frequency to vary the variable current of the oscillator according to the sensed ambient temperature; In the electronic ballast circuit comprising a logic circuit and an output terminal connected to the oscillator, the temperature sensing unit is a temperature compensation by adjusting the ratio between the resistor, the ambient temperature in the entire circuit senses the oscillator accordingly By varying the current of the frequency is characterized in that to maintain a constant.

The reference voltage generator includes an OP-AMP for amplifying the applied reference voltage (V _BG ), a first transistor Q ₁ having an output voltage of the OP-AMP as a base voltage, and the first transistor ( _One end is connected to the emitter of Q ₁ ) and the other end is composed of a first resistor R ₁ , which is an external resistor that is grounded. At this time, the reference voltage generating unit changes the temperature gradient of the reference voltage (V _BG ) maintaining a constant voltage according to the temperature by dropping the reference voltage (VBG) as the temperature drops at a low temperature below a certain temperature, The magnitude of the reference current is also reduced, and as a result, it is desirable to design the power to lower the lighting frequency to enhance the lighting characteristics.

Meanwhile, the temperature sensing unit has one end of the second resistor R ₂ connected to the reference voltage V _BG , and the other end of the second resistor R ₂ has a third resistor R ₃ and the second transistor ( Q ₂ ), the emitter of the second transistor Q ₂ is connected to the fourth resistor R ₄ , and the collector of the second transistor Q ₂ is connected to the third transistor Q of the switching unit. ₃ ), the third and fourth resistors R ₃ and R ₄ are grounded.

More specifically, when the ambient temperature is changed so that the value of the second to fourth resistors R ₂ to R ₄ is changed, the second transistor Q ₂ has a detected ambient temperature of 100. As it rises above the degree, the temperature sensing signal is gradually increased by turning on, so that the frequency is constant by varying the current input to the oscillator, or the ambient temperature is varied so that the second transistor Q ₂ is detected. As the ambient temperature rises to a high temperature above a certain temperature such as 100 ° C., the temperature is turned on by gradually turning on, thereby increasing the current input to the oscillator and varying the frequency to decrease the output power. .

Lastly, the switching unit may be configured of third and fourth transistors which receive a signal output from the reference current source generator and a temperature sensing signal output from the temperature sensing unit and output a variable current to the oscillator.

Hereinafter, an embodiment of an electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosed contents may be thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art.

2 is a circuit diagram illustrating an embodiment of an electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention.

As shown in FIG. 2, the electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention includes a switching unit 20 and an oscillation frequency that largely determine an operation state of the reference current source generator 10 and the entire integrated circuit. In the electronic ballast control circuit consisting of an oscillator 30 and logic circuit 40 and an output terminal 50 connected to an external driving circuit for applying the, the external temperature sensor 60 is connected.

The reference current source generator 10 includes an OP-AMP, a first transistor Q ₁ , and a first resistor R ₁ , and a reference voltage V _BG is applied to the anode terminal of the OP-AMP and amplified. do. The current I ₁ flowing in the first transistor Q ₁ is kept constant at a low temperature or more close to 0 degrees, and the first resistor R ₁ is an external resistance, and the temperature is nearly 0 ° C. The constant current I ₁ also changes with the ambient temperature, which means that the frequency is constant and thus the power consumption is constant. The first resistor R ₁ may be embedded in the integrated circuit IC. In this case, the first resistor R ₁ may have the same effect as using an external resistor through temperature compensation by the temperature coefficient of the resistance in the integrated circuit IC.

Meanwhile, the collector of the first transistor Q ₁ is connected to the emitter of the third transistor Q ₃ of the switching unit 20. The switching unit 20 has a base connected to the third transistor Q ₃ and the fourth transistor Q ₄ , and the emitter of the fourth transistor Q ₄ is connected to the capacitor, the second switch, and the oscillator. Therefore, the switching unit 20 is turned on when the total temperature of the entire integrated circuit is within a predetermined range, and thus the first current I ₁ received from the reference current source generator 10 and the temperature sensing unit 60 to be described later. The third current (I _CT ) of the sum of the second current (I ₂ ) received from the output is output, and the operation is stopped by turning OFF at an extremely high temperature such as 160 ° C.

The flow path of the third current I _CT received from the switching unit 20 is connected to the oscillator 30, the logic circuit 40, and an external output terminal 50.

Here, the temperature sensing unit 60 indirectly connected to the entire integrated circuit is a kind of sensor, and senses the temperature inside the entire integrated circuit to start operation when the temperature inside the entire circuit reaches a predetermined temperature or more. Frequency temperature characteristics can be adjusted by sensing the temperature of the sensor, thereby maintaining a constant brightness and power consumption over the operating temperature range. As shown in FIG. 2, the temperature sensing unit 60 includes second to fourth resistors R ₂ to R ₄ and a second transistor Q ₂ . One end of the second resistor R ₂ is connected to the reference voltage V _BG , and the other end thereof is connected to a third resistor R ₃ and a base of the second transistor Q ₂ . The third other end of the resistor (R ₃₎ is grounded, is connected to the emitter a fourth resistance (R ₄₎ of the second transistor (Q _2), the other end of said fourth resistor (R ₄₎ is grounded. In addition, the second collector of the transistor (Q ₂₎ is the third is connected to the emitter of the transistor (Q _3), the switching consisting of the third transistor (Q ₃₎ and fourth transistor (Q ₄₎ connected to its base The unit 20 outputs a variable current to the oscillator 30 through the collector of the fourth transistor Q ₄ .

In the temperature sensing circuit having the above configuration, since the base of the second transistor Q ₂ is connected in parallel to the connection node of the second and third resistors R ₂ and R ₃ , the second transistor Q The base voltage of ₂ ) is the voltage at both ends of the third resistor R ₃ . Therefore, the base voltage of the second transistor Q ₂ is determined by the resistance values of the second and third resistors R ₂ and R ₃ .

For example, the turn-on voltage of the second transistor Q ₂ drops by -2 mV whenever the ambient temperature rises by one degree. In addition, since the resistance value of the resistance rises by 0.03% of the initial resistance value each time the temperature rises by one degree, the variation of the resistance value according to the temperature of the resistance is generally ignored. Thus, the second base voltage of the transistor (Q ₂₎ acts as a positive function for temperature, and the second transistor (Q ₂₎ turn-on voltages of the peripheral by acting as a function of the sound with respect to the temperature temperature As R rises, the base voltage and turn-on voltage of the second transistor Q ₂ coincide with a specific temperature. Then, the output signal of the temperature sensing circuit output through the collector of the second transistor Q ₂ outputs a low level signal from a high level signal, so that the temperature around the circuit has reached a predetermined temperature. You will be notified. Here, the temperature to be detected by the temperature sensing circuit can be changed. Since the base voltage of the second transistor Q ₂ is a voltage between both ends of the third resistor R ₃ , the base voltage of the second transistor Q ₂ can be adjusted as the resistance ratio of the second and third resistors R ₂ and R ₃ . The second adjustment of the base voltage of the transistor (Q ₂₎ of the second means to adjust the current (I _2), and wherein the adjusting a second current (I ₂₎ a first current (I ₂₎ and the combined third current Through I _CT , the frequency increases as the temperature inside the entire integrated circuit rises above a certain temperature. That is, the temperature compensation to be performed in the control circuit of the electronic ballast according to the present invention is made through the resistance ratio of the second and third resistors R ₂ and R ₃ .

In the electronic ballast according to the present invention, the low and high temperature levels that hinder the operation of the system are specified in the circuit. In this case, as a method for stably operating the ballast, since additional temperature compensation is required through frequency adjustment, 0 degrees and 100 degrees are required. As in the example, a specific temperature to be detected by the temperature sensor 60 may be set.

The electronic ballast may not be turned on or may be incompletely lit due to insufficient heating of the filament even with the same preheating time at low temperatures such as 0 ° C. or less. At this time, the operating frequency should be lowered a little than normal temperature so that it can be turned on in any case. In addition, when the frequency drops at a high temperature such as 100 ° C. or higher, since excessive heat generation may adversely affect the life of a system including the light, the second to fourth resistances may be determined by the temperature sensing unit 60 by setting a specific temperature. When the value of the passive element such as R ₂ to R ₄ ) is changed, the frequency is constant by varying the current applied to the oscillator 30.

In this way, if the temperature of the integrated circuit is variable, the temperature sensing unit 60 detects a temperature when the value of the passive element is changed, or detects a temperature when the temperature of the integrated circuit rises above a predetermined specific temperature. There are ways to do this.

As a result, when the ambient temperature rises above a certain temperature in the integrated circuit, it is possible to obtain a kind of protective effect of gradually increasing the operating frequency in proportion thereto and gradually reducing power consumption. In addition, when the ultra-high temperature, such as about 160 ° C., turns off the entire integrated circuit in the switching unit 20 to stop the operation of the entire integrated circuit, it is possible to protect the circuit and the entire system at a high temperature.

The characteristics of the reference voltage V _BG in the circuit shown in FIG. 2 can be seen in FIG. 3A. The reference voltage uses a commonly used bandgap reference voltage circuit, which maintains a substantially constant voltage within the normal operating temperature range, and when the ambient temperature falls below a specific temperature such as 0 ° C, the voltage also falls together. By reducing the value of the first current I ₁ , the lighting characteristic at low temperature can be enhanced. At this time, the temperature gradient characteristic of the bandgap reference voltage can be arbitrarily manipulated on the circuit, and it can be used to designate the magnitude of the current value according to the temperature within the operating temperature range including the low temperature. The first current I ₁ flowing at a constant value within a normal operating temperature range and the second current I ₂ gradually increasing above a certain high temperature such as 100 ° C. or higher and having a value of almost zero below 100 ° C .; The characteristics of the third current I _CT decreasing at a low temperature below 0 ° C. and gradually increasing at a high temperature above 100 ° C. while maintaining a constant value in a predetermined temperature range as a sum of the first and second currents are shown in FIG. 3B. can do.

4A and 4B are diagrams showing improved frequency characteristics and power consumption characteristics even with an increase in the ambient temperature through an electronic ballast control circuit having a temperature compensated frequency characteristic according to the present invention as shown in FIG. The amount of power consumed is proportional to the brightness of a lighting such as a fluorescent lamp which is ultimately connected through the output terminal 50. By reducing the power consumption at high temperature in FIG. 4B, even if the brightness of the light is slightly reduced, the life of the lighting such as a fluorescent lamp is extended. You can.

5A and 5B show that when the ambient temperature increases to the maximum temperature of about 160 ° C to 180 ° C in the electronic ballast control circuit according to the present invention as shown in FIG. For the protection of the system, the frequency characteristics and power consumption characteristics are shown when the entire bias circuit is stopped by switching off. In this case, the entire circuit and the system can be protected at an ultrahigh temperature of 160 ° C or higher.

In the above described and described with respect to the preferred embodiment of the present invention, this invention is not limited to the specific embodiments described above, gunshot in the technical field to which the subject innovation belongs without departing from the gist of the subject innovation claimed in the claims Anyone of ordinary skill in the art can make various modifications as well as such modifications are within the scope of the claims.

Electronic ballast control circuit according to the present invention to prevent the life is shortened by the frequency reduction and the increase of power consumption caused by the increase of the ambient temperature during the operation of the characteristics of the article, the temperature compensation through the frequency adjustment over a certain temperature In the case of increasing the current flow by using the resistance ratio, the frequency and power consumption are kept constant or slightly reduced, thereby extending the lifespan.

Claims (7)

A reference voltage generator for generating a reference signal having a set level regardless of a change in ambient temperature; A switching unit which determines whether the entire circuit is operated; A temperature sensing unit for sensing an ambient temperature in the entire circuit and generating a temperature sensing signal corresponding thereto; An oscillator for generating an oscillation frequency to vary the variable current of the oscillator according to the sensed ambient temperature; In the electronic ballast circuit comprising a logic circuit and an output terminal connected to the oscillator, The temperature sensing unit includes resistors R ₂ , R ₃ , and R ₄ , which are peripheral passive elements, and a transistor Q _2. Temperature compensation is performed by adjusting a ratio between the resistors. Accordingly, the electronic ballast control circuit having a temperature compensated frequency characteristic, characterized in that to maintain a constant frequency by varying the current of the oscillator. The method of claim 1, The reference voltage generator includes an OP-AMP for amplifying a reference voltage V _BG to be applied, a first transistor Q ₁ having an output voltage of the OP-AMP as a base voltage, and the first transistor Q _1. An electronic ballast control circuit having a temperature compensated frequency characteristic, characterized in that the first end (R ₁ ) is connected to one of the emitter and the other end is grounded external resistance. The method of claim 2, The reference voltage generator partially changes the temperature gradient of the reference voltage V _BG that maintains a constant voltage according to temperature so that the reference voltage VBG also drops as the temperature drops at a low temperature below a specific temperature, thereby reducing the reference current. The size of the electronic ballast is also reduced, and as a result, the electronic ballast control circuit designed to enhance the lighting characteristics by lowering the lighting frequency The method of claim 1, One end of the second resistor R ₂ is connected to the reference voltage V _BG , and the other end of the second resistor R ₂ is connected to the third resistor R ₃ and the second transistor Q _2. ) Is connected to a base of the second transistor (Q ₂ ) is connected to a fourth resistor (R ₄ ), the collector of the second transistor (Q ₂ ) is the third transistor (Q ₃ ) of the switching unit. Is connected to the emitter of the electronic ballast control circuit having a temperature compensated frequency characteristic, characterized in that the third and fourth resistors (R ₃ and R ₄ ) are grounded. The method of claim 4, wherein When the ambient temperature is changed so that the value of the second to fourth resistors R ₂ to R ₄ is changed, the second transistor Q ₂ increases as the sensed ambient temperature rises above 100 degrees. The electronic ballast control circuit having a temperature-compensated frequency characteristic, characterized in that the frequency is constant by turning the ON to increase the temperature detection signal, thereby varying the current input to the oscillator. The method of claim 4, wherein When the ambient temperature of the entire circuit rises above a predetermined specific temperature, the second transistor Q ₂ is turned on as the detected ambient temperature rises above a specific high temperature such as 100 ° C. An electronic ballast control circuit having a temperature compensated frequency characteristic, characterized in that the temperature sensing signal is gradually increased, thereby reducing the output power by varying the frequency by varying the current input to the oscillator. The method of claim 1, The switching unit is a temperature compensated frequency comprising a third and fourth transistor for receiving a signal output from the reference current source generator and a temperature sensing signal output from the temperature sensing unit and outputs a variable current to the oscillator Electronic ballast control circuit with characteristics.

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