JP3157174U - Electronic ballast - Google Patents

Abstract

An electronic ballast capable of preventing abnormal heating of a filament is provided. A high-frequency resonant lighting circuit electrically connected to both ends of a fluorescent lamp, a level setting circuit for setting and outputting an upper limit voltage and a lower limit voltage, and a detection circuit electrically connected to both ends of the fluorescent lamp And a control circuit connected between the level setting circuit and the detection circuit, and a protection circuit connected between the control circuit and the high frequency resonant lighting circuit. [Selection] Figure 1

Description

  The present invention relates to an electronic ballast used to stabilize lighting of a fluorescent lamp.

  In general, when a fluorescent lamp is directly connected to a power source due to its negative characteristics, once the lamp current starts to flow, the current rapidly increases, and the electrodes and sealing portions of the arc tube are instantaneously destroyed. Therefore, if an electronic ballast that oscillates at a high frequency of several tens of kilohertz to turn on the fluorescent lamp is inserted and connected between the AC power supply and the lamp, the lamp current is properly controlled and the discharge of the lamp is maintained in a stable state. It is possible to reduce the noise and flickering, reduce the power used for lighting, and extend the life of the fluorescent lamp. For this reason, such fluorescent lamps are being generalized.

  As the fluorescent lamp is used, the filament on one side may usually be worn first at both ends of the arc tube. Therefore, the degree of wear of the filament at both ends differs at the end of the life of the fluorescent lamp. Overcurrent may flow through the filament, causing abnormal heating, melting the lamp holder, or burning the ballast.

  The present invention has been made in view of the above problems, and an object thereof is to provide an electronic ballast capable of preventing abnormal heating of a filament by detecting a rectifying effect in advance.

  In order to achieve the above object, the present invention provides an electronic ballast for lighting a fluorescent lamp disposed between a power source and a fluorescent lamp, wherein the fluorescent lamp is electrically connected to both ends of the fluorescent lamp. A high-frequency resonant lighting circuit that generates and oscillates a high-frequency voltage to be lit, a level setting circuit that sets and outputs an upper limit voltage and a lower limit voltage, and is electrically connected to both ends of the fluorescent lamp. A detection circuit that detects a change, and is connected between the level setting circuit and the detection circuit so that a signal can be input and output, and an upper limit voltage or a lower limit voltage from the level setting circuit and a voltage change value from the detection circuit When the voltage change value is equal to or higher than the upper limit voltage or lower than the lower limit voltage, a control circuit that generates a comparison voltage and outputs it as an abnormal signal can be input / output Protection that is connected between the control circuit and the high-frequency resonant lighting circuit and that operates to stop the lighting of the fluorescent lamp while disabling the high-frequency resonant lighting circuit when the abnormal signal is input. An electronic ballast characterized by comprising a circuit.

  In the electronic ballast, the control circuit is preferably connected to the level setting circuit and the detection circuit so that signals can be input and output, and the voltage change value is not less than the upper limit voltage or not more than the lower limit voltage. And a voltage comparison unit that generates a comparison voltage and outputs it as the abnormal signal, and a switch unit that is driven by the abnormal signal to conduct and outputs the abnormal signal to the protection circuit.

  In the electronic ballast, the voltage comparison unit preferably has an inverting input terminal and a non-inverting input terminal to which the upper limit voltage and the voltage change value are input, respectively, and the voltage change value is equal to or higher than the upper limit voltage. And an inverting amplifier that generates a comparison voltage and outputs the comparison signal, and an inverting input terminal and a non-inverting input terminal to which the voltage change value and the lower limit voltage are input, respectively, and the voltage change value is When the voltage is lower than the lower limit voltage, a non-inverting amplifier that generates a comparison voltage and outputs it as the abnormal signal is formed.

  In the electronic ballast, the switch unit is preferably electrically connected to an output terminal of the inverting amplifier and the non-inverting amplifier, and is electrically connected to the protection circuit, and is conducted by the abnormal signal. It consists of two diodes.

  In the electronic ballast, the voltage change value by the detection circuit is, for example, a partial pressure on one side at both ends of the fluorescent lamp.

  According to the electronic ballast of the present invention, the control circuit compares the voltage change value from the detection circuit with the upper limit voltage or the lower limit voltage set in accordance with the fluorescent lamp, thereby making the high frequency resonant lighting circuit inoperable. A signal is output so that the fluorescent lamp can be prevented from being turned on. Therefore, by detecting the rectifying effect due to the difference in the degree of aging of the filaments generated at both ends of the fluorescent lamp, it is possible to prevent the fluorescent lamp from being turned on as appropriate, so that abnormal heating of the filament can be prevented and the use of the lighting device is safe It is possible to improve the performance.

It is a circuit diagram of the electronic ballast concerning one embodiment by this invention used for a fluorescent lamp. It is a block diagram of FIG.

  Next, embodiments of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a circuit diagram of an electronic ballast according to an embodiment of the present invention used in a fluorescent lamp, and FIG. 2 is a block diagram of FIG. In the figure, 201 indicates an external power source, 200 indicates a lighting facility connected to the external power source 201, such as a fluorescent lamp, and 100 indicates an electronic ballast connected to the external power source 201 and electrically connected to the fluorescent lamp 200. The fluorescent lamp may be a general fluorescent lamp, and may be a T8, T5, or other standard lamp.

  The electronic ballast 100 is electrically connected to the fluorescent lamp 200 and operates to turn on the fluorescent lamp 200. As an example, the electronic ballast 100 is electrically connected to both ends of the fluorescent lamp 200, and the fluorescent lamp 200 is A high-frequency resonant lighting circuit 3 that generates and oscillates a high-frequency voltage to be lit, a level setting circuit 4 that is connected in parallel to a DC input power source (Vdc) 201, a detection circuit 5 that is connected in parallel to both ends of the fluorescent lamp 200, A control circuit 6 connected between the level setting circuit 4 and the detection circuit 5 so that signals can be input / output, and a protection circuit connected between the control circuit 6 and the high-frequency resonance lighting circuit 3 so that signals can be input / output 7 is included.

  The high-frequency resonant lighting circuit 3 includes, for example, a high-frequency half-bridge chip IC01 and transistors Q01 and Q02 so that a high-frequency voltage for lighting the fluorescent lamp 200 can be stably output. Since the high frequency resonant lighting circuit 3 has been widely used conventionally, detailed description thereof is omitted.

  The detection circuit 5 includes, for example, capacitors C04 and C05, a resistor R05, and a diode Z01 so as to detect a change in voltage caused by the fluorescent lamp 200. In this example, the voltage change due to the fluorescent lamp 200 is the divided voltage V1 of the end voltage of the capacitor C04. In this configuration, when the rectification effect has not yet occurred, that is, when the aging state in the filaments (not shown) at both ends of the fluorescent lamp 200 is substantially the same, the end voltage of the capacitor C04 is half of the power source (Vdc) 201. However, when one of the filaments at both ends of the fluorescent lamp 200 ages first, the end voltage of the capacitor C04 also changes greatly. Therefore, the detection circuit 5 can obtain the voltage change value V1 by the fluorescent lamp 200 as the detection voltage by detecting the end voltage of the capacitor C04. When the aging state of the filaments at both ends reaches a predetermined difference, a rectifying effect occurs. For example, when the rectifying effect is first generated in the filament electrically connected to the end of the inductance T01, the detection voltage V1 changes greatly, and when the rectifying effect is generated in the filament electrically connected to the end of the capacitor C4, The detection voltage V1 changes relatively small.

  The level setting circuit 4 sets the upper limit voltage VA and the lower limit voltage VB based on the upper limit value and the lower limit value of the divided voltage V1 at the capacitor C04 end and outputs them to the control circuit 6, for example, resistors R01, R02, R03. And capacitors C01 and C02.

  The control circuit 6 can input and output a signal between the level setting circuit 4 and the detection circuit 5 so as to compare the upper limit voltage or the lower limit voltage from the level setting circuit 4 with the voltage change value from the detection circuit 5. It is connected. In this example, the control circuit 6 is connected to the level setting circuit 4 and the detection circuit 5 so that signals can be input and output, and the upper limit voltage VA or the lower limit voltage VB from the level setting circuit 4 and the voltage from the detection circuit 5. When the voltage change value is greater than or equal to the upper limit voltage or less than the lower limit voltage, the comparison value is generated and output as an abnormal signal to the voltage comparison unit 61 that is driven by the abnormal signal and is conducted. Is provided to the protection circuit 7.

  For example, the voltage comparison unit 61 receives an inverting amplifier OP1 having an inverting input terminal and a non-inverting input terminal to which an upper limit voltage VA and a voltage change value V1 are input, and a voltage change value V1 and a lower limit voltage VB, respectively. And a non-inverting amplifier OP2 having an inverting input terminal and a non-inverting input terminal.

  The inverting amplifier OP1 generates a comparison voltage when the voltage change value V1 is equal to or higher than the upper limit voltage, that is, when a rectification effect is generated in the filament electrically connected to the inductance T1, and sends the comparison voltage to the switch unit 62 as an abnormal signal. Output.

  The non-inverting amplifier OP2 generates a comparison voltage and outputs it as an abnormal signal when the voltage change value V1 is equal to or lower than the lower limit voltage VB, that is, when a rectification effect occurs in the filament electrically connected to the capacitor C04.

  In this example, the switch unit 62 is electrically connected to the output terminals of the inverting amplifier OP1 and the non-inverting amplifier OP2 and electrically connected to the protection circuit 7 so as to be conducted by the abnormal signal. It consists of two diodes D02 and D02. When the diode D02 or D02 is turned on by the abnormal signal from the inverting amplifier OP1 or the non-inverting amplifier OP2, the abnormal signal is output to the protection circuit 7.

  The protection circuit 7 is connected between the control circuit 6 and the high frequency resonance lighting circuit 3 so that signals can be input and output. When an abnormal signal is input, the protection circuit 7 is operated so as to ground the power source of the high-frequency half-bridge chip IC01 in the high-frequency resonant lighting circuit 3. By driving the high-frequency half-bridge chip IC01, the driving of the transistors Q01 and Q02 can be stopped, and the fluorescent lamp 200 can be prevented from being turned on. The configuration of the protection circuit 7 is conventionally known, and detailed description thereof is omitted here.

  When the fluorescent lamp 200 to which the electronic ballast 100 of the present invention is attached is turned on, the control circuit 6 compares the detection voltage V1 with the upper limit voltage VA or the lower limit voltage VB as needed. When the rectifying effect occurs in the fluorescent lamp 200, a result that the detection voltage V1 is equal to or higher than the upper limit voltage VA or lower than the lower limit voltage VB is obtained, and is output to the protection circuit 7 as an abnormal signal. When an abnormal signal is input to the protection circuit 7, the high-frequency resonant lighting circuit 3 can be disabled so that the fluorescent lamp is not lit. Therefore, the filament on one side of the fluorescent lamp 200 does not become high temperature due to the rectifying effect, so that the ballast can be prevented from being burned out and the life of the lamp can be extended.

  The upper limit voltage VA and the lower limit voltage VB by the level setting circuit 4 are determined depending on the type of the lamp. Therefore, the constituent elements can be changed to set different upper limit voltage and lower limit voltage depending on the type of the lamp 200. It is not limited to the configuration.

  As described above, according to the electronic ballast of the present invention, when the rectifying effect is generated, the fluorescent lamp 200 can be prevented from being lit, so that the use safety of the lamp 200 and the electronic ballast 100 can be improved.

DESCRIPTION OF SYMBOLS 201 Power supply 200 Fluorescent lamp 100 Electronic ballast 3 High frequency resonance lighting circuit 4 Level setting circuit 5 Detection circuit 6 Control circuit 61 Voltage comparison part 62 Switch part 7 Protection circuit

Claims (5)

In an electronic ballast for lighting a fluorescent lamp arranged between a power source and a fluorescent lamp,
A high-frequency resonant lighting circuit that is electrically connected to both ends of the fluorescent lamp and oscillates by generating a high-frequency voltage for lighting the fluorescent lamp;
A level setting circuit that sets and outputs an upper limit voltage and a lower limit voltage;
A detection circuit that is electrically connected to both ends of the fluorescent lamp and detects a change in voltage due to the fluorescent lamp;
Connected between the level setting circuit and the detection circuit so that a signal can be input and output, and compares an upper limit voltage or a lower limit voltage from the level setting circuit with a voltage change value from the detection circuit, and the voltage change A control circuit that generates a comparison voltage when the value is equal to or higher than the upper limit voltage or lower than the lower limit voltage, and outputs an abnormal signal;
When the abnormal signal is input and connected between the control circuit and the high frequency resonance lighting circuit so that a signal can be input and output, the high frequency resonance lighting circuit is disabled and the fluorescent lamp is turned on. An electronic ballast comprising a protection circuit that operates to stop. The control circuit includes:
When the voltage change value is equal to or higher than the upper limit voltage or lower than the lower limit voltage, a comparison voltage is generated and output as the abnormal signal. A voltage comparator;
2. The electronic ballast according to claim 1, further comprising: a switch unit that is driven by the abnormal signal to be conductive and outputs the abnormal signal to the protection circuit. The voltage comparison unit
It has an inverting input terminal and a non-inverting input terminal to which the upper limit voltage and the voltage change value are input, respectively. If the voltage change value is equal to or higher than the upper limit voltage, a comparison voltage is generated and output as the abnormal signal. An inverting amplifier;
It has an inverting input terminal and a non-inverting input terminal to which the voltage change value and the lower limit voltage are input, respectively. If the voltage change value is less than or equal to the lower limit voltage, a comparison voltage is generated and output as the abnormal signal. The electronic ballast according to claim 2, comprising a non-inverting amplifier.   The switch unit is composed of two diodes that are electrically connected to the output terminals of the inverting amplifier and the non-inverting amplifier, and are electrically connected to the protection circuit, and are conducted by the abnormal signal. The electronic ballast according to claim 3.   5. The electronic ballast according to claim 2, wherein the voltage change value by the detection circuit is a partial pressure on one side at both ends of the fluorescent lamp.

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