JP2009135072A - High pressure discharge lamp electronic ballast - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp electronic ballast which does not operate with an overcurrent close to short circuit which may occur in starting, and which protects and stops when the overcurrent close to the short circuit continuously flows in an end of a life. <P>SOLUTION: The high pressure discharge lamp electronic ballast includes a current detection resistance for detecting a current which flows through a high pressure discharge lamp, and a voltage detection resistance for detecting a voltage of the high pressure discharge lamp. A control circuit detects a voltage of the current detection resistance after a power is applied to the high pressure discharge lamp. When the voltage of the current detection resistance reaches beyond a predetermined value, a voltage detected by the voltage detection resistance around a phase 170° or 350° is observed. When the voltage detected by the voltage detection resistance is beyond the predetermined value, one is counted and when the number of counts reaches beyond a predetermined value, an output current of the high pressure discharge lamp electronic ballast is stopped. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp electronic ballast which is a lighting device for a high pressure discharge lamp (hereinafter also referred to as a lamp) such as a metal halide lamp. More particularly, the present invention relates to an electronic ballast for a high pressure discharge lamp that does not operate at an overcurrent close to a short circuit that may occur at the start, and that stops protection when an overcurrent close to a short circuit flows continuously at the end of its life.

Supply to high-pressure discharge lamps to protect electronic ballasts and high-pressure discharge lamps in the event of abnormal phenomena at the end of the life of high-pressure discharge lamps (astigmatism, half-wave discharge, slow leak or outer tube discharge) An inverter circuit that adjusts power, a first lighting determination circuit that determines the lighting state of the high-pressure discharge lamp, and a second lighting that continues or stops the operation of the inverter circuit in response to the determination result of the first lighting determination circuit The first lighting determination circuit determines the lighting state of the high pressure discharge lamp, and the second lighting determination circuit continues the operation of the inverter circuit according to the substantially total of the determination results of the first lighting determination circuit, or A high-pressure discharge lamp electronic ballast for determining stoppage has been proposed (see, for example, Patent Document 1).
JP 2005-100830 A

  However, in general, high pressure discharge lamp electronic ballasts may behave like an abnormal event at the end of life at start-up. When an abnormal phenomenon such as a slow leak occurs, the high-pressure discharge lamp electronic ballast described in Patent Document 1 stops protection when the abnormal state continues for a specified time. In this case, there is a problem that a good lamp having a long starting time may be protected and stopped. If the specified time is lengthened, it is possible to distinguish (discriminate) the end-of-life lamp from the normal lamp. However, if the specified time is long, the end-of-life lamp is operated for a long time. There has been a problem that the stress applied to the electronic ballast of the high-pressure discharge lamp increases.

  The present invention has been made to solve the above-described problems, and does not operate at an overcurrent close to a short circuit that may occur at the start, and an overcurrent close to a short circuit flows continuously at the end of the life. An object of the present invention is to provide a high-pressure discharge lamp electronic ballast that stops protection.

  In addition, by detecting the range and duration of the lamp current value at the time of starting, a high-pressure discharge lamp electronic ballast that protects the electronic ballast and the high-pressure discharge lamp in the event of an abnormal phenomenon at the end of the life of the high-pressure discharge lamp The purpose is to provide.

An electronic ballast for a high-pressure discharge lamp according to the present invention includes a starting means for generating a starting voltage for starting discharge of the high-pressure discharge lamp, a current supply means for controlling a current flowing during discharge of the high-pressure discharge lamp, and a starting A high pressure discharge lamp electronic ballast having a control circuit for controlling the means and the current supply means,
A current detection resistor for detecting the current flowing through the high-pressure discharge lamp;
A voltage detection resistor for detecting the voltage of the high-pressure discharge lamp,
The control circuit
After turning on the high-pressure discharge lamp, detect the voltage of the current detection resistor,
When the voltage of the current detection resistor exceeds a predetermined value, the voltage detected by the voltage detection resistor having a phase near 170 ° or a phase near 350 ° is observed.
If the voltage detected by this voltage detection resistor is greater than or equal to a predetermined value, 1 is counted,
When the count number exceeds a predetermined number, the output current of the high-pressure discharge lamp electronic ballast is stopped.

An electronic ballast for a high-pressure discharge lamp according to the present invention includes a starting means for generating a starting voltage for starting discharge of the high-pressure discharge lamp, a current supply means for controlling a current flowing during discharge of the high-pressure discharge lamp, and a starting A high pressure discharge lamp electronic ballast having a control circuit for controlling the means and the current supply means,
A current detection resistor for detecting the current flowing through the high-pressure discharge lamp;
A voltage detection resistor for detecting the voltage of the high-pressure discharge lamp,
The control circuit
After turning on the high-pressure discharge lamp, detect the voltage of the current detection resistor,
When the voltage of the current detection resistor exceeds a predetermined value, the voltage detected by the voltage detection resistor having a phase near 170 ° or a phase near 350 ° is observed.
If the voltage detected by this voltage detection resistor is greater than or equal to a predetermined value, 1 is counted,
When the count number exceeds the predetermined number, 1 is counted as the protection count and the count number is reset.
When the protection count exceeds a predetermined number, the output current of the high-pressure discharge lamp electronic ballast is stopped.

  The high-pressure discharge lamp electronic ballast according to the present invention is characterized in that the generation of the starting voltage of the starting means is stopped when the protection count number exceeds a predetermined number.

An electronic ballast for a high-pressure discharge lamp according to the present invention includes a starting means for generating a starting voltage for starting discharge of the high-pressure discharge lamp, a current supply means for controlling a current flowing during discharge of the high-pressure discharge lamp, and a starting A high pressure discharge lamp electronic ballast having a control circuit for controlling the means and the current supply means,
A current detection resistor for detecting the lamp current flowing in the high-pressure discharge lamp,
The control circuit
Detecting the lamp current flowing in the current detection resistor after the starting means has applied a starting voltage to the high pressure discharge lamp,
When the detected lamp current is within a predetermined range smaller than the lamp current flowing through the current detection resistor after applying the starting voltage to a normal high-pressure discharge lamp, and detected for a predetermined time, the output of the high-pressure discharge lamp electronic ballast The current is stopped.

An electronic ballast for a high-pressure discharge lamp according to the present invention includes a starting means for generating a starting voltage for starting discharge of the high-pressure discharge lamp, a current supply means for controlling a current flowing during discharge of the high-pressure discharge lamp, and a starting A high pressure discharge lamp electronic ballast having a control circuit for controlling the means and the current supply means,
A current detection resistor for detecting the lamp current flowing in the high-pressure discharge lamp,
The control circuit
Detecting the lamp current flowing in the current detection resistor after the starting means has applied a starting voltage to the high pressure discharge lamp,
When the detected lamp current is within a predetermined range smaller than the lamp current flowing through the current detection resistor after applying the starting voltage to a normal high-pressure discharge lamp and is detected for a predetermined time, the starting voltage of the high-pressure discharge lamp for a predetermined time is detected. The application is paused.

  According to the above configuration, the high voltage discharge lamp electronic ballast according to the present invention does not operate with an overcurrent close to a short circuit that may occur at the time of start-up. The discharge lamp and high pressure discharge lamp electronic ballast can be protected.

Embodiment 1 FIG.
First, an abnormal phenomenon at the end of life in a high pressure discharge lamp such as a metal halide lamp will be described.

The following are known as abnormal phenomena that occur at the end of the life of high-pressure discharge lamps such as metal halide lamps.
(1) Astigmatism A pair of electrodes (tungsten) is installed in the arc tube of the lamp. At the end of the lamp life, a phenomenon occurs in which the lamp cannot be started and lit due to wear of the electrodes.
(2) Half-wave discharge phenomenon Occurs due to deterioration of the electrode on one side with the life of the lamp. In this state, the lamp current flowing in the lamp is asymmetrical between positive and negative, and is almost short-circuited on one side and almost unloaded on the other side.
(3) Slow Leak Phenomenon This is a phenomenon in which gas in the arc tube of the lamp leaks into the outer tube and discharge continues in a state where the lamp voltage is lower than normal.
(4) Outer tube discharge This is a phenomenon in which a slow leak further proceeds and discharge occurs between electrodes in the outer tube.

  When an abnormal phenomenon as described above occurs, the lamp often leaks, and an overcurrent close to a short circuit continuously flows through the lamp. At this time, the high pressure discharge lamp electronic ballast may be overloaded and break down. However, a similar phenomenon may occur when a normal lamp that is not at the end of its life starts. Therefore, even if a protective device for protecting the high-pressure discharge lamp electronic ballast is created when the above-mentioned abnormal phenomenon occurs, there is a possibility that a protective malfunction occurs at the start of a normal lamp.

  The inventors of the present invention have compared the starting waveform (lamp current and lamp voltage) at the time of starting a normal lamp and the starting waveform of the leak clamp, and as a result, found that there is a difference described later. Taking advantage of this difference, an example of protection that does not perform protection even if the above abnormal phenomenon occurs when a normal lamp starts, and that can perform protection only for leak clamp at the end of life explain.

  FIGS. 1 to 5 are diagrams showing the first embodiment. FIG. 1 is a circuit diagram of a high-pressure discharge lamp electronic ballast 100. FIG. 2 is a starting waveform (lamp current, lamp) of a non-defective lamp (a) and a leak lamp (b). FIG. 3 is a control flowchart for detecting leak clamp, FIG. 4 is a control flowchart for detecting a leak clamp, and FIG. 5 is a commercial power source 1 for a modified high voltage discharge lamp electronic ballast 100. FIG. 4 is a circuit diagram in which the rectifier circuit 2 and the booster inverter 3 are omitted.

  The configuration of the high-pressure discharge lamp electronic ballast 100 will be described with reference to FIG. The rectifier circuit 2 is composed of a diode bridge composed of a diode D21, a diode D22, a diode D23, and a diode D24 that performs rectification by taking in AC power from the commercial power supply 1, and a capacitor 21 connected between both output terminals of the diode. Composed.

  The step-up inverter 3 has an inductance L31 connected at one end to the high potential side output end of the rectifier circuit 2, an FET Q31 (connected to the other end of the inductance L31 and the low potential side output end of the rectifier circuit 2 respectively at the drain and source. Field effect transistor), a diode D31 to which the other end of the inductance L31 and the anode are connected, and a capacitor C31 connected between the cathode of the diode D31 and the low potential side output end of the rectifier circuit 2.

  The step-down inverter 4 includes a FET Q41 (an example of a switching element) to which a cathode and a drain of a diode D31 are connected, a diode D41 to which the cathode and an anode are connected to the source of the FET Q41 and the low-potential side output terminal of the rectifier circuit 2, The capacitor L41 is connected between the other end of the inductance L41 and the low-potential side output end of the rectifier circuit 2.

  The lighting circuit 5 includes a series-connected FETQ51 and FETQ52 connected in parallel with the capacitor C41, a series-connected FETQ53 and FETQ54 connected in parallel with the FETQ51 and FETQ52, and a starting voltage generating circuit 6 (an example of a starting unit). . A high-pressure discharge lamp 7 (hereinafter also referred to as a lamp) is connected in series to the starting voltage generation circuit 6. A voltage obtained by superimposing a starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6 on the output voltage (rectangular wave) output from the lighting circuit 5 is applied to the high pressure discharge lamp 7. The rectifier circuit 2, the step-up inverter 3, the step-down inverter 4, and the lighting circuit 5 are examples of current supply means.

  A current detection resistor 20 for detecting the lamp current is connected to the low potential side between the lighting circuit 5 and the step-down inverter 4.

  The voltage of the current detection resistor 20 is input to the control circuit 10.

  Two voltage detection resistors 30 for measuring the lamp voltage are connected to the high potential side of the lighting circuit 5.

  A voltage between the two voltage detection resistors 30 is input to the control circuit 10.

  FIG. 2 is a diagram comparing the starting waveforms (lamp current and lamp voltage) of the non-defective lamp (a) and the leak clamp (b). As shown in FIG. 2A, in the non-defective lamp, after the dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6, the lamp current continues to flow until the rectangular wave is switched. On the other hand, as shown in FIG. 2B, in the leak clamp, a lamp current flows after dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6, but the base voltage is being applied. In some cases, current may not flow.

  Using this characteristic difference, after detecting the lamp current of dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6, the lamp voltage of phase 170 ° or phase 350 ° is observed, NG is counted when the lamp voltage is higher than a predetermined value, and protection is stopped when the NG count exceeds a predetermined number (for example, 100 times) (the output current of the high-pressure discharge lamp electronic ballast 100 is stopped). To do).

  The reason why the lamp voltage at the phase of 170 ° or the phase of 350 ° is observed is that the leakage voltage can be reliably detected by looking at the lamp voltage immediately before the polarity is switched.

  Here, the dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generation circuit 6 is detected by the lamp current, but this may be detected by the lamp voltage.

  Further, although the lamp voltage having a phase of 170 ° or a phase of 350 ° is observed, it may be observed by a lamp current.

  A control flow in which the control circuit 10 detects leak clamp will be described with reference to FIG. The following control is performed by the microcomputer executing a program stored in the microcomputer (microcomputer).

  In S10, the commercial power source 1 is turned on.

  In S <b> 11, the control circuit 10 determines whether or not the lamp current of dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6 is detected based on the voltage of the current detection resistor 20.

  When a lamp current of dielectric breakdown (discharge) is detected in S11, the process proceeds to S12, and a lamp voltage with a phase of 170 ° or near 350 ° is observed.

  If the lamp current of dielectric breakdown (discharge) is not detected in S11, the process proceeds to S17. The operation of S17 will be described later.

  It is determined whether the lamp voltage observed in S13 is equal to or higher than a specified value.

  When the lamp voltage observed in S13 is equal to or higher than the specified value, the process proceeds to S14 and NG is counted (1 is counted).

  If no lamp voltage exceeding the specified value is observed in S13, the process proceeds to S17.

  In S15, it is determined whether the NG count exceeds a predetermined number.

  When the NG count exceeds the predetermined number in S15, the process proceeds to S16, and the output current of the high-pressure discharge lamp electronic ballast 100 is stopped (protection stop). The protection stop may be a method of stopping the generation of the starting voltage of the starting voltage generating circuit 6.

  If the NG count does not exceed the predetermined number in S15, the process proceeds to S17.

  In S17, it is determined whether or not the lamp is lit.

  If it is determined in S17 that the lamp is lit, the process proceeds to S18 (lighting mode).

  If it is determined in S17 that the lamp is not lit, the process returns to S11.

  As described above, according to the present embodiment, the control circuit 10 detects the voltage of the current detection resistor 20 after turning on the commercial power supply 1 to the high-pressure discharge lamp 7, and the voltage of the current detection resistor has a predetermined value. When it exceeds, the voltage detected by the voltage detection resistor 30 whose phase is around 170 ° or near 350 ° is observed. When the voltage detected by the voltage detection resistor 30 is equal to or greater than a predetermined value, 1 is counted. However, if the count exceeds a predetermined number, the output current of the high-pressure discharge lamp electronic ballast 100 is stopped, so that it does not operate at an overcurrent close to a short circuit that may occur at the start, and is short-circuited at the end of its life. When an overcurrent close to is continuously flowing, a high-pressure discharge lamp electronic ballast 100 is obtained that stops protection (protects the high-pressure discharge lamp 7 and the high-pressure discharge lamp electronic ballast 100).

  In the control flowchart for detecting leak clamp in FIG. 3, when the NG count exceeds the predetermined number in S15, the protection is immediately stopped in S16. However, in order to prevent malfunction, the protection is stopped after repeating this several times. May be.

  FIG. 4 is a control flowchart for detecting leak clamp to prevent malfunction. S19 to S21 are added to FIG.

  If the NG count exceeds the predetermined number in S15, the process proceeds to S21 and pauses. That is, the lamp is cooled and returned to the initial state. Then the lamp is restarted. In S19, the protection count is performed (1 is counted as the protection count), and the NG count number is reset.

  Proceeding to S20, it is determined whether the protection count number exceeds a predetermined number (for example, three times).

  When the protection count exceeds the predetermined number in S20, the process proceeds to S16, and the output current of the high-pressure discharge lamp electronic ballast 100 is stopped (protection stop). The protection stop may be a method of stopping the generation of the starting voltage of the starting voltage generating circuit 6.

  If the protection count does not exceed the predetermined number in S20, the process proceeds to S17.

  As described above, when the protection count number exceeds the predetermined number, the output current of the high-pressure discharge lamp electronic ballast 100 is stopped, so that malfunction can be prevented.

  The step-down inverter 4 and the lighting circuit 5 shown in FIG. 1 may be constituted by a half bridge circuit as shown in FIG. In a cycle in which the FET Q53 performs high-frequency switching, the energy of the inductance L41 is fed back to the capacitor C52 when the FET Q53 is turned off. In the cycle in which the FET Q54 is switched at high frequency, the energy of the inductance L41 is fed back to the capacitor C51 when the FET Q54 is turned off.

  Through the above operation, the rectangular wave AC power similar to that of the high-pressure discharge lamp electronic ballast 100 of FIG. 1 can be applied to the lamp.

  When the lamp is a leak clamp at the end of its life, the high pressure discharge lamp 7 and the high pressure discharge lamp electronic ballast 100 are protected in the same manner as in the first embodiment. However, the control circuit 10 detects the lamp voltage based on the difference between the potential between the inductance L41 and the starting voltage generation circuit 6 and the potential between the capacitor C51 and the capacitor C52.

Embodiment 2. FIG.
In the first embodiment, the non-defective lamp continues to flow until the switching of the rectangular wave after the dielectric breakdown (discharge) by the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6. On the other hand, in the leak clamp, the lamp current flows after dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6, but the current may not flow during the application of the base voltage. Using the difference, an example of protection has been described in which a protection operation is not performed even if an abnormal phenomenon occurs when a normal lamp starts, and a protection operation can be performed only for a leak clamp at the end of its life.

  In the present embodiment, another protection example in which a protection operation can be performed only on a leak clamp at the end of life using the phenomenon described below will be described.

  In the non-defective (normal) lamp, the lamp current gradually increases after a predetermined time (about 150 msec) after the dielectric breakdown (discharge) by the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6. On the other hand, the discharge lamp (leak clamp) in the outer tube has a long current that is smaller than the lamp current of a non-defective (normal) lamp after dielectric breakdown (discharge) due to the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6. Keep flowing for hours.

  FIGS. 6 and 7 show the measurement results of the lamp voltage and the lamp current when starting the non-defective lamp and the discharge lamp in the outer tube using the high-pressure discharge lamp electronic ballast 100 of FIG.

  FIG. 6 shows the result of measuring the lamp current after dielectric breakdown (discharge) by the starting voltage (high-voltage pulse) generated by the starting voltage generating circuit 6 for a non-defective (normal) lamp. As shown in FIG. 6, a non-defective (normal) lamp has a lamp current that increases after a current of approximately 0.5 A flows for 50 ms or more at the start, and a lamp current of approximately 1.2 A flows.

  On the other hand, as shown in FIG. 7, the discharge lamp (leak clamp) in the outer tube flows a lamp current of 30 mA or less for a long time when starting. In one example, the lamp current of 30 mA or less is 8 to 23 mA.

  Therefore, the lamp current after dielectric breakdown (discharge) by the starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6 is detected, and the detected lamp current value is within a predetermined range (for example, 8 to 23 mA) for a predetermined time. (For example, when 20 cycles (70 Hz, approximately 280 msec)) are continued, it can be determined that the lamp is a discharge lamp (leak clamp) in the outer tube.

  Next, the operation of the control circuit 10 (FIG. 1 or FIG. 5) will be described. First, for comparison, a general lamp protection operation flow will be described with reference to FIG. The following control is performed by the microcomputer executing a program stored in the microcomputer (microcomputer).

The flow of a general lamp protection operation of the control circuit 10 shown in FIG. 8 is as follows.
(1) S100: The commercial power source 1 is turned on.
(2) S110: Apply a starting voltage (high voltage pulse) generated by the starting voltage generating circuit 6 to the lamp.
(3) S120: determining whether the predetermined value _{A 0} or more of the lamp current detecting a predetermined cycles or more. The predetermined value _{A 0} is, for example, 350mA. Further, the predetermined cycle is, for example, 24 cycles.
(4) S130: If it detects a predetermined cycle over the predetermined value _{A 0} or more lamp current at S120, the process proceeds to the lighting mode.
(5) S140: If not detected a predetermined cycle over the predetermined value _{A 0} or more lamp current at S120, after the commercial power supply 1 is turned on, a predetermined time (e.g., 20 minutes) to determine whether elapsed.
(6) S150: When a predetermined time (for example, 20 minutes) has elapsed after the commercial power source 1 is turned on in S140, the protection is stopped.

  Even in the general flow of FIG. 8, the discharge lamp (leak clamp) in the outer tube can be protected and stopped. However, it takes at least 20 minutes for the protection to stop, for example. Then it takes too much time. The discharge lamp in the outer tube, which is the end-of-life lamp, is operated for a long time, and the stress applied to the outer lamp (leak clamp) and the high-pressure discharge lamp electronic ballast 100 increases.

FIG. 9 is a flowchart showing an example of the lamp protection operation of the control circuit 10 in the present embodiment. A difference from the flow of FIG. 8 is that S160 is provided between S110 and S120. In S160, it determines whether it has detected a predetermined time of the lamp current of a predetermined range _(A 1 ~A _2). Here, A _{1 to} A ₂ <A ₀ . For example, A ₀ is 350 mA, and A _{1 to} A ₂ are 8 to 23 mA. The predetermined time is, for example, 20 cycles (70 Hz, approximately 280 msec). When the lamp current in the predetermined range (A _{1 to} A ₂ ) is detected for a predetermined time in S160, the process proceeds to S150 and the protection is stopped.

  Thus, according to the flow of FIG. 9, if the lamp is a discharge lamp (leak clamp) in the outer tube, it can be detected in a short time of 20 cycles (70 Hz, approximately 280 msec). The stress applied to the high-pressure discharge lamp electronic ballast 100 can be reduced without operating the discharge lamp in the outer tube which is the end-of-life lamp for a long time.

FIG. 10 is a flowchart showing another example of the lamp protection operation of the control circuit 10 in the present embodiment. 9 is different from FIG. 9 in that when a lamp current in a predetermined range (A _{1 to} A ₂ ) is detected for a predetermined time in S160, application of a starting voltage (high voltage pulse) generated by the starting voltage generation circuit 6 for a predetermined time in S170. It is a point to pause. The pause time is, for example, 90 seconds.

  Thereafter, the application of the starting voltage (high voltage pulse) generated by the starting voltage generation circuit 6 is resumed, and the process proceeds to S140. When a predetermined time (for example, 20 minutes) elapses after the commercial power source 1 is turned on in S140, the process proceeds to S150 and the protection is stopped.

  If the lamp is a discharge lamp (leak clamp) in the outer tube, the protection is stopped about 20 minutes after starting. However, since most of about 20 minutes are resting, the stress given to the high pressure discharge lamp electronic ballast 100 is light.

Even when the lamp is normal, the lamp current in a predetermined range (A _{1 to} A ₂ ) may flow for a predetermined time at the start for some reason. In that case, if the lamp is normal, the lamp current A ₀ larger than the lamp current in a predetermined range (A _{1 to} A ₂ ) flows in the second and subsequent startings, and the lighting mode is shifted to.

As described above, the control of FIG. 10 can prevent the normal lamp from being protected and stopped due to a rare phenomenon of a normal lamp (a lamp current in a predetermined range (A _{1 to} A ₂ ) flows for a predetermined time at the start). Have

  Although it takes about 20 minutes to stop the protection of the discharge lamp (leak clamp) in the outer tube, most of it is in a resting state, so that the stress applied to the high-pressure discharge lamp electronic ballast 100 is light.

  Although the high pressure discharge lamp electronic ballast 100 of FIG. 1 has been described, this embodiment is also effective for the high pressure discharge lamp electronic ballast 100 of FIG.

FIG. 3 shows the first embodiment, and is a circuit diagram of a high-pressure discharge lamp electronic ballast 100. The figure which shows Embodiment 1 and the figure which compared the starting waveform (lamp current, lamp voltage) of a non-defective lamp (a) and a leak clamp (b). FIG. 5 is a diagram showing the first embodiment, and is a control flowchart diagram for detecting leakage clamp. FIG. 5 is a diagram showing the first embodiment, and is a control flowchart diagram of a modified example for detecting a leak clamp. FIG. 5 is a diagram illustrating the first embodiment, and is a circuit diagram in which the commercial power source 1, the rectifier circuit 2, and the booster inverter 3 of a modification of the high-pressure discharge lamp electronic ballast 100 are omitted. FIG. 6 is a diagram showing the second embodiment, and shows a waveform of a lamp voltage and a lamp current when a normal lamp is started. FIG. 6 is a diagram illustrating the second embodiment, and is a diagram illustrating waveforms of a lamp voltage and a lamp current at the time of starting an outer tube discharge lamp (leak clamp). The flowchart figure of the protection operation | movement of the general lamp | ramp shown for a comparison. FIG. 9 is a diagram illustrating the second embodiment and is a flowchart illustrating an example of a lamp protection operation. FIG. 9 shows the second embodiment, and is a flowchart showing another example of the protection operation of the lamp.

Explanation of symbols

  1 commercial power supply, 2 rectifier circuit, 3 step-up inverter, 4 step-down inverter, 5 lighting circuit, 6 starting voltage generation circuit, 7 high-pressure discharge lamp, 10 control circuit, 20 current detection resistor, 30 voltage detection resistor, 40 voltage detection resistor, 50 Voltage detection resistor, 100 High pressure discharge lamp electronic ballast.

Claims (5)

A starting means for generating a starting voltage for starting discharge of the high pressure discharge lamp, a current supply means for controlling a current flowing during the discharge of the high pressure discharge lamp, and the starting means and the current supply means are controlled. In a high pressure discharge lamp electronic ballast having a control circuit,
A current detection resistor for detecting a current flowing in the high-pressure discharge lamp;
A voltage detection resistor for detecting the voltage of the high-pressure discharge lamp,
The control circuit includes:
After turning on the high pressure discharge lamp, the voltage of the current detection resistor is detected,
When the voltage of the current detection resistor exceeds a predetermined value, the voltage detected by the voltage detection resistor having a phase near 170 ° or a phase near 350 ° is observed,
If the voltage detected by this voltage detection resistor is greater than or equal to a predetermined value, 1 is counted,
When the count exceeds a predetermined number, the output current of the high-pressure discharge lamp electronic ballast is stopped. A starting means for generating a starting voltage for starting discharge of the high pressure discharge lamp, a current supply means for controlling a current flowing during the discharge of the high pressure discharge lamp, and the starting means and the current supply means are controlled. In a high pressure discharge lamp electronic ballast having a control circuit,
A current detection resistor for detecting a current flowing in the high-pressure discharge lamp;
A voltage detection resistor for detecting the voltage of the high-pressure discharge lamp,
The control circuit includes:
After turning on the high pressure discharge lamp, the voltage of the current detection resistor is detected,
When the voltage of the current detection resistor exceeds a predetermined value, the voltage detected by the voltage detection resistor having a phase near 170 ° or a phase near 350 ° is observed,
If the voltage detected by this voltage detection resistor is greater than or equal to a predetermined value, 1 is counted,
When the count number exceeds a predetermined number, count 1 as a protection count and reset the count number,
The high-pressure discharge lamp electronic ballast characterized by stopping the output current of the high-pressure discharge lamp electronic ballast when the protection count exceeds a predetermined number.   3. The high-pressure discharge lamp electronic ballast according to claim 2, wherein when the protection count exceeds a predetermined number, generation of the starting voltage of the starting means is stopped. A starting means for generating a starting voltage for starting discharge of the high pressure discharge lamp, a current supply means for controlling a current flowing during the discharge of the high pressure discharge lamp, and the starting means and the current supply means are controlled. In a high pressure discharge lamp electronic ballast having a control circuit,
A current detection resistor for detecting a lamp current flowing in the high pressure discharge lamp,
The control circuit includes:
Detecting the lamp current flowing through the current detection resistor after the starting means has applied a starting voltage to the high-pressure discharge lamp;
When the detected lamp current is within a predetermined range smaller than the lamp current flowing through the current detection resistor after applying a starting voltage to the normal high-pressure discharge lamp, and detected for a predetermined time, the high-pressure discharge lamp electron An electronic ballast for a high-pressure discharge lamp characterized by stopping the output current of the ballast. A starting means for generating a starting voltage for starting discharge of the high pressure discharge lamp, a current supply means for controlling a current flowing during the discharge of the high pressure discharge lamp, and the starting means and the current supply means are controlled. In a high pressure discharge lamp electronic ballast having a control circuit,
A current detection resistor for detecting a lamp current flowing in the high pressure discharge lamp,
The control circuit includes:
Detecting the lamp current flowing through the current detection resistor after the starting means has applied a starting voltage to the high-pressure discharge lamp;
When the detected lamp current is within a predetermined range smaller than the lamp current flowing through the current detection resistor after a starting voltage is applied to the normal high-pressure discharge lamp and detected for a predetermined time, the high-pressure discharge lamp for a predetermined time A high-pressure discharge lamp electronic ballast characterized by stopping application of a starting voltage to the lamp.

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