JP2013222640A - Illumination protective circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination protective circuit which appropriately protects a circuit in accordance with a situation of opening and closing of an illumination load and suppresses high heat generated by voltage drop by a resistor.SOLUTION: A protective circuit applied to an illumination device which has a high frequency transformer having a primary coil and a secondary coil, and a bridge driver unit includes: a common grounding unit configured by connecting the primary coil and the secondary coil of the high frequency transformer with a ground end of the bridge driver unit; a rectifier unit which is a half-wave rectifier unit or a full-wave rectifier unit for supplying a current by connecting to the common grounding unit; and an illumination load to which a high-frequency current of the secondary coil of the high frequency transformer is input by connecting to the half-wave rectifier unit or the full-wave rectifier unit.

Description

  The present invention relates to a protection circuit for lighting, and more particularly to a protection circuit suitable for application to a lighting device including a high-frequency transformer and a half-bridge driver unit.

  In the lighting circuit, for example, a half-bridge or full-bridge circuit is used for an electronic ballast commonly used in a cold cathode tube or a hot cathode tube, and the product name is referred to as an HD lamp controller. IR2153, UCC3305, or UC1871 is commercially available. Regarding these characteristics, the electronic ballast integrated circuit such as a driver integrated circuit power supply circuit and a driver integrated circuit shutdown circuit are provided in the secondary circuit of the high frequency transformer of the lighting circuit from the product description. There is no description of technology related to protection of

  According to the prior art, power is supplied by a half-bridge or full-bridge driver unit via a voltage drop resistor having a large wattage. For this reason, high heat is generated and affects the circuit. Therefore, an illumination protection circuit is required that appropriately protects the circuit in accordance with the opening / closing state of the illumination load and suppresses the high heat generated due to the voltage drop by the resistor.

  US Pat. Nos. 7042161 and 8018173 both disclose an electronic ballast provided with a half-bridge driver circuit, and US Pat. No. 7,369,421 discloses an electronic ballast including a full-bridge driver circuit. A vessel is disclosed. However, the techniques disclosed in these publications are electronic devices such as, for example, providing a secondary coil of a high-frequency transformer in an illumination circuit with a power supply by a driver integrated circuit and a circuit for performing a shutdown operation by the driver integrated circuit. No technology is discussed that aims to provide protection for integrated circuits in the formula stabilization period.

United States Patent No. 7042161 United States Patent No. 8018173 US Pat. No. 7,369,421

  It is an object of the present invention to provide a lighting protection circuit that appropriately protects a circuit according to the opening / closing state of a lighting load and suppresses high heat generated due to a voltage drop by a resistor.

  Accordingly, the present inventor has conducted intensive research in view of the drawbacks found in the prior art, and as a result, has a high-frequency transformer including at least a primary coil and a secondary coil, and an illumination device including a bridge driver unit. A protection circuit applied to a common ground unit configured by connecting a primary coil and a secondary coil of the high-frequency transformer to the ground terminal of the bridge driver unit; A rectification unit that is a half-wave rectification unit that supplies current, or a full-wave rectification unit; and a high-frequency of the secondary coil of the high-frequency transformer connected to the half-wave rectification unit or the full-wave rectification unit The present invention has been completed based on the knowledge that the problem can be solved by a lighting protection circuit including a lighting load to which a current is input.

  In the lighting protection circuit having the above-described configuration, when the lighting load is on, the rectifier circuit supplies current from the bridge driver unit, and when the lighting load is off, the current supply from the bridge driver unit is stopped to perform lighting. Achieve circuit protection.

  Further, it is possible to meet different lighting needs by providing a full-wave rectification unit, a half-wave rectification unit and / or a photoelectric coupler circuit based on the magnitude of the resistance of the illumination load. The illumination load may be a hot cathode tube, a cold cathode tube, an external electrode fluorescent tube, or a ceramic fluorescent lamp tube.

The present invention will be specifically described below.
The protection circuit according to claim 1 is a protection circuit applied to a lighting device including a high-frequency transformer including at least a primary coil and a secondary coil, and a bridge driver unit.
A common ground unit configured such that a primary coil and a secondary coil of the high-frequency transformer are connected to a ground terminal of the bridge driver unit;
A half-wave rectifier unit comprising one voltage drop resistor and one rectifier diode, or a full-wave rectifier unit comprising two voltage drop resistors and two rectifier diodes, and the half-wave rectifier unit A rectification unit, or a rectification unit that the full wave rectification unit connects to the common ground unit to provide current;
A lighting load connected to the half-wave rectification unit or to the full-wave rectification unit and to which a high-frequency current of the secondary coil of the high-frequency transformer is input.

  The protection circuit according to claim 2 is the half-wave rectification unit according to claim 1 or the full-wave rectification unit connected in series to the lighting load, and further connected in parallel with both ends of the secondary coil of the high-frequency transformer. To do.

  According to a third aspect of the present invention, the protection circuit according to the third aspect further includes an output end of the half-wave rectification unit according to the first aspect or the full-wave rectification unit connected to a power supply end of the bridge driver unit.

  According to a fourth aspect of the present invention, the bridge driver unit according to the first aspect is a half-bridge driver or a full-bridge driver.

  According to a fifth aspect of the present invention, there is provided the protection circuit according to the first aspect, wherein the protection circuit includes a plurality of transistors and a plurality of photoelectric coupler units, and emitters of the plurality of transistors are connected to the common ground unit. A shutdown unit configured to stop the operation of the bridge driver unit in accordance with the opening / closing state of the illumination load.

  In the protection circuit according to the sixth aspect, the photoelectric coupler unit according to the fifth aspect and the illumination load are connected in series.

  In a protection circuit according to a seventh aspect, any one of the plurality of photoelectric coupler units according to the sixth aspect further includes a light-emitting diode having a P-type end and an N-type end, and a phototransistor.

  In the protection circuit according to an eighth aspect, the P-type end of the light emitting diode according to the seventh aspect is connected to one end of the high-frequency transformer, and the N-type end is connected to one end of the lighting load.

  According to a ninth aspect of the present invention, the P-type end of the light emitting diode according to the eighth aspect is connected to the other end of the high-frequency transformer, and the N-type end is connected to the other end of the lighting load.

  According to a tenth aspect of the present invention, in the protection circuit according to the fifth aspect, the phototransistor of the photoelectric coupler unit according to the fifth aspect includes a first phototransistor and a second phototransistor, and the emitters of the first phototransistor and the second phototransistor. Is connected to the base electrode of the second transistor, the collector of the second transistor is connected to the base electrode of the first transistor, and the collector of the first transistor is connected to the shutdown unit of the bridge driver unit.

It is a circuit diagram by the 1st Example of the protection circuit for illumination of this invention. It is a circuit diagram by the 2nd Example of the protection circuit for illumination of this invention. It is a circuit diagram by the 3rd Example of the protection circuit for illumination of this invention.

  The present invention provides a lighting protection circuit that appropriately protects a circuit according to the switching state of a lighting load and suppresses high heat generated due to a voltage drop by a resistor, and at least a primary coil And a secondary coil, a protection circuit applied to a lighting device comprising a bridge driver unit, and the primary coil and secondary coil of the high-frequency transformer are connected to the bridge driver unit. A common ground unit configured to be connected to the ground end, a half-wave rectifier unit that is connected to the common ground unit to supply current, a rectifier unit that is a full-wave rectifier unit, and the half-wave rectifier unit. Or a lighting load connected to the full-wave rectifying unit and receiving a high-frequency current of the secondary coil of the high-frequency transformer. In order to describe in detail the structure and characteristics of such a protection circuit for illumination, a specific example will be given and described below with reference to the drawings.

  FIG. 1 discloses a first embodiment of a lighting protection circuit according to the present invention. In the circuit disclosed in the drawing, when an alternating current AC is input from a power supply input terminal, it is input to the full bridge rectifier BD from the input terminal of the full bridge rectifier BD connected to the fuse FS via the fuse FS.

  The positive and negative voltage output terminals of the full bridge rectifier BD are connected in parallel to both ends of the smoothing capacitor C1. A voltage drop resistor R1 is connected to one end of the smoothing capacitor C1, and a smoothing capacitor C2 and a constant voltage diode are connected to the other end. The current output from the full bridge rectifier BD reaches the voltage drop resistor R1 and is filtered by the smoothing capacitor C2 and the constant voltage diode to obtain a constant voltage.

  Further, when the current reaches the power supply terminal VCC of the half bridge driver integrated circuit HBDIC, the field effect transistor M1 and the field effect transistor M2 are also activated.

  Next, current is input from both ends of the secondary coil S of the high-frequency transformer TR to the illumination load LD and the diodes D1 and D2 in the full-wave rectifier circuit. The A terminal of the secondary coil S, the voltage drop resistor R2, the voltage drop resistor R3, and the B terminal of the lighting load LD are connected in series, and the D terminal is used as a common ground terminal.

  When the illumination load LD is at an arbitrary load, a voltage drop occurs at both ends of the voltage drop resistor R2 and the voltage drop resistor R3.

  According to the principle of operation when current is supplied to the half-bridge driver integrated circuit HBDIC, when the A terminal is at a positive potential, the positive voltage is charged from the diode D1 to the smoothing capacitor C2, and the half-bridge driver integrated circuit HBDIC. When the illumination load LD is on, no current is supplied to the power supply terminal VCC of the half bridge driver integrated circuit HBDIC, and the object of protecting the illumination circuit is achieved.

  When the illumination load LD is off, the object of protecting the illumination circuit is achieved without supplying current to the power supply terminal VCC of the half-bridge driver integrated circuit HBDIC.

  When the B terminal is a positive voltage, the positive voltage is charged from the diode D2 to the smoothing diode C2, supplied to the power supply terminal VCC of the half bridge driver integrated circuit HBDIC, and when the illumination load LD is on, the half bridge driver integrated circuit HBDIC The purpose of protecting the illumination circuit is achieved without supplying current to the power supply terminal VCC.

  As is clear from this, the output of the full-wave rectifier circuit is the cathode end (N end) of the diodes D1 and D2, and is connected to the power supply end VCC of the half-bridge driver integrated circuit HBDIC. The voltage drop resistor R1 has only a starting action, and the full-wave rectifier circuit supplies current to the rear half-bridge driver integrated circuit HBDIC. Therefore, the thermal wattage value of the voltage drop resistor R1 is greatly reduced. In this case, the negative potential at the D end and the ground end of the primary coil P of the high-frequency transformer TR are connected to form a common ground end.

  The half-bridge driver integrated circuit HBDIC in the embodiment described above may be a full-bridge driver integrated circuit.

  FIG. 2 discloses a second embodiment of the illumination protection circuit according to the present invention. In the circuit disclosed in the drawing, when an alternating current is input from a power supply input terminal, it is input to the full bridge rectifier BD from the input terminal of the full bridge rectifier BD connected to the fuse FS via the fuse FS.

  The positive and negative voltage output terminals of the full-bridge rectifier BD are connected in parallel to both ends of the smoothing capacitor C1, and supply current to the voltage drop resistor R1. When a constant voltage is obtained by filtering of the smoothing capacitor C2 and the constant voltage diode ZD1, and a current is supplied to the power supply terminal VCC of the half bridge driver integrated circuit HBDIC, the half bridge driver integrated circuit HBDIC is activated, and the field effect transistor M1 and the field effect Transistor M2 is also activated.

  Next, the A terminal and C terminal of the secondary coil S of the high frequency transformer TR supply current to the illumination load LD, the diode D4 of the half-wave rectifier circuit, and the voltage drop resistor R4.

  The B terminal of the illumination load LD and the voltage drop resistor R4 are connected in series. When the illumination load LD is in an arbitrary load, the voltage is effective at both ends of the voltage drop resistor R4.

  Speaking from the principle of the power supply operation of the half-bridge driver integrated circuit HBDIC, when the B terminal is a positive potential, the positive voltage is charged from the diode D4 to the smoothing capacitor C2, and is supplied to the power supply terminal VCC of the half-bridge driver integrated circuit HBDIC. Provided and the object of protecting the lighting circuit is achieved.

  As is clear from this, the output terminal of the half-wave rectifier circuit is the cathode terminal (N terminal) of the diode D4 and is connected to the power supply terminal VCC of the half-bridge driver integrated path HBDIC.

  The action of the voltage drop resistor R1 is only for start-up, and the half-wave rectifier circuit provides all the power for the half-bridge driver integrated circuit HBDIC. Thus, the thermal wattage value of the voltage drop resistor R1 is greatly reduced.

  In this case, the A end is connected to the negative potential and the ground end of the primary coil P of the high-frequency transformer TR to form a common ground end. The diode D3 (also referred to as a backflow prevention diode) is provided to prevent the positive voltage at the B end from flowing back to the A end.

  The half bridge driver integrated circuit HBDIC in this embodiment may be a full bridge driver integrated circuit.

  FIG. 3 discloses a third embodiment of a lighting protection circuit according to the present invention. According to the drawing, the circuit disclosed in FIG. 2 is provided with a shut-out circuit for stopping the operation of the half-bridge driver integrated circuit HBDIC, so that a more complete illumination protection circuit is obtained.

  As is apparent from the drawing, according to the theory of operation of the shut-out circuit of the half-bridge driver integrated circuit HBDIC, when the C terminal of the secondary coil S of the high-frequency transformer TR is a positive potential, the positive current is the first photoelectric coupler. From the PHI photodiode and the shunt resistor RS1, the illumination load LD is passed through to the shunt resistor RS2 and the diode D8 of the second photoelectric coupler PH2, and further returns to the B end of the secondary coil S.

  At the same time, from the positive end of the full-bridge rectifier BD, through the voltage drop resistor R5 and the diode D5, the collector and emitter of the phototransistor on the secondary side of the first photoelectric coupler PHI are reached, and further to the base electrode of the transistor Q2. . In this case, the collector and emitter of the transistor Q2 are energized, and the base electrode of the transistor Q1 is turned on. Therefore, the operation of the half bridge driver integrated circuit HBDIC is not affected.

  When the illumination load LD is off, the collector and emitter of the secondary transistor of the first photoelectric coupler PH1 are turned off, the base electrode of the transistor Q1 is at a high potential, and the collector and emitter of the transistor Q1 are short-circuited. Therefore, the operations of the half bridge driver integrated circuit and the HBDIC are stopped.

  In this case, the base electrode of the transistor Q1 has a high potential, and from the positive voltage terminal of the smooth rectifier C1 at the positive and negative voltage output terminals of the full bridge rectifier BD, through the voltage drop resistor R5, and further through the constant voltage diode ZD3, It is supplied to the base electrode of the transistor Q1.

  When the B terminal of the secondary coil S of the high-frequency transformer has a positive potential, a positive current flows from the photoelectric diode of the second photoelectric coupler PH2 and the shunt resistor RS2 to the C terminal of the secondary coil S through the illumination load LD and the diode D7. Go back.

  At the same time, from the positive voltage output terminal of the full-bridge rectifier BD, through the voltage drop resistor R5, further through the diode D6, to the collector and emitter of the secondary photoelectric transistor of the second photoelectric coupler PH2, and further to the base electrode of the transistor Q2 To.

  In this case, the collector and emitter of the transistor Q2 are energized, and the base electrode of the transistor Q1 is at a low potential. Therefore, the operation of the half bridge driver integrated circuit HBDIC is not affected.

  When the illumination load LD is off, the collector and emitter of the transistor Q2 are turned off, the base electrode of the transistor Q1 is at a high potential, and the collector and emitter of the transistor Q1 are short-circuited. Therefore, the operations of the half bridge driver integrated circuit and the HBDIC are stopped.

  In this case, the base electrode of the transistor Q1 is at a high potential, and from the positive voltage terminal of the smoothing capacitor C1 at the positive voltage output terminal of the full bridge rectifier BD, through the voltage drop resistor R5, and further through the constant voltage diode ZD3, Supplied to the base electrode.

  The half bridge driver integrated circuit HBDIC in this embodiment may be a full bridge driver integrated circuit.

  The above is a preferred embodiment of the present invention, and does not limit the scope of the present invention. Therefore, any modifications or changes that can be made by those skilled in the art, which are made within the spirit of the present invention and have an equivalent effect on the present invention, belong to the scope of the claims of the present invention. And

HBDIC half-bridge driver integrated circuit.
AC AC current FS Fuse BD Full bridge rectifier C1, C2 Smoothing capacitor R1, R2, R3, R4, R5 Voltage drop resistor RS1, RS2 Shunt resistor obstruction.
VCC power supply terminals M1, M2 field effect transistor TR high frequency transformer P primary coil S secondary coil LD lighting load D1, D2, D3, D4, D5, D6, D7, D8 diode Q1, Q2 transistor ZD1, ZD3 constant voltage diode PH1 1st photoelectric coupler PH2 2nd photoelectric coupler

Claims (10)

A protection circuit applied to a lighting device comprising a high-frequency transformer comprising at least a primary coil and a secondary coil and a bridge driver unit,
A common ground unit configured such that a primary coil and a secondary coil of the high-frequency transformer are connected to a ground terminal of the bridge driver unit;
A half-wave rectifier unit comprising one voltage drop resistor and one rectifier diode, or a full-wave rectifier unit comprising two voltage drop resistors and two rectifier diodes, the half-wave rectifier unit A rectifying unit, or the full wave rectifying unit connected to the common ground unit to provide current;
A protection circuit comprising: a half-wave rectification unit; or a lighting load connected to the full-wave rectification unit and receiving a high-frequency current of the secondary coil of the high-frequency transformer. The protection according to claim 1, wherein the half-wave rectification unit or the full-wave rectification unit is connected in series with the lighting load, and is further connected in parallel with both ends of the secondary coil of the high-frequency transformer. circuit. The protection circuit according to claim 1, wherein the half-wave rectification unit or the full-wave rectification unit further includes an output terminal connected to a power supply terminal of the bridge driver unit. The protection circuit according to claim 1, wherein the bridge driver unit is a half-bridge driver or a full-bridge driver. The protection circuit includes a plurality of transistors and a plurality of photoelectric coupler units, and the emitters of the plurality of transistors are connected to the common ground unit, and the plurality of photoelectric couplers according to the open / close state of the lighting load. The protection circuit according to claim 1, further comprising a shutdown unit configured to stop the operation of the bridge driver unit. 6. The protection circuit according to claim 5, wherein the photoelectric coupler unit and the illumination load are connected in series. The protection circuit according to claim 6, wherein any one of the plurality of photoelectric coupler units further includes a light emitting diode having a P-type end and an N-type end, and a phototransistor. The protection circuit according to claim 7, wherein a P-type end of the light emitting diode is connected to one end of the high-frequency transformer, and an N-type end is connected to one end of the lighting load. 9. The protection circuit according to claim 8, wherein a P-type end of the light emitting diode is connected to the other end of the high-frequency transformer, and an N-type end is connected to the other end of the lighting load. The phototransistor of the photoelectric coupler unit is composed of a first phototransistor and a second phototransistor, the emitters of the first phototransistor and the second phototransistor are connected to the base electrode of the second transistor, and 6. The protection circuit according to claim 5, wherein a collector of the second transistor is connected to a base electrode of the first transistor, and a collector of the first transistor is connected to the shutdown unit of the bridge driver unit.

Images