JP3823680B2 - Power supply device for discharge lamp - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a discharge lamp power supply apparatus, for example, a discharge lamp power supply apparatus for lighting a high-intensity high-pressure mercury vapor lamp used as a light source for a projector.
[0002]
[Prior art]
Conventionally, metal halide lamps and high-pressure mercury vapor lamps have been used as high-intensity light sources.
[0003]
In recent years, high-pressure mercury vapor lamps with increased vapor pressure of mercury have been effective as a light source for projectors used in luminous flux control devices such as liquid crystals, and the amount of mercury enclosed in the lamp tends to increase. is there.
[0004]
However, as the amount of mercury enclosed in the lamp increases, even if the igniter is successfully started at the time of starting the lamp, there is a problem that the lamp will disappear after several seconds to several tens of seconds. There was found.
[0005]
As a result of experiments and observations under many conditions, the inventors have found that this problem is caused by the condensation and deposition of mercury on the cathode during the cooling period when the lamp is extinguished.
[0006]
To briefly explain this phenomenon, as is well known, electrons are likely to be emitted from liquid mercury, and therefore, when liquid mercury is present on the cathode, a very low interelectrode voltage, for example, 15 volts is used. Arc discharge can be realized at about 20 volts.
[0007]
If the discharge starts with liquid mercury adhering to the cathode, arc discharge first appears, but the mercury on the cathode evaporates quickly. At this time, the mercury on the cathode first evaporates in the portion facing the anode, and the discharge location gradually moves toward the base of the cathode. When mercury completely evaporates from above the cathode, including the one at the base of the cathode, the arc discharge at the low interelectrode voltage is terminated, and a glow discharge is started.
[0008]
At this time, the impedance between the electrodes is low in the arc discharge state but is high in the glow discharge state. Therefore, in order to maintain the glow discharge, it is necessary to supply a relatively high voltage between the electrodes. When the voltage output from the lamp cannot cope with the rapidly increasing voltage, the lamp goes off at the moment of transition to glow discharge.
[0009]
Therefore, if the glow discharge can be maintained without extinguishing, the temperature at the tip of the cathode rises, and it becomes possible to supply thermoelectrons eventually, and then the arc discharge is performed to maintain the steady lighting state of the discharge lamp. be able to.
[0010]
In the past, the problem of this lamp extinguishing was not very obvious because the amount of mercury was so small that liquid mercury on the cathode could be scattered during the igniter's operating period, and therefore the low interelectrode voltage This is because the glow discharge was able to be maintained strongly by the high voltage generated by the igniter after the arc discharge was completed.
[0011]
Therefore, it may be possible to maintain the glow discharge by continuously operating the igniter after the liquid mercury on the cathode is scattered by the operation of the igniter. However, in such a method, the electrode is consumed and the arc tube is blackened. It was not a practical method.
[0012]
Conventionally, a means for solving the problem caused by the adhesion of mercury to the electrode of a high-pressure mercury vapor lamp has been proposed in Japanese Patent Application Laid-Open No. 10-116590.
[0013]
This is to reduce the cooling rate of the cathode in the process of gradually cooling the lamp after the lamp is extinguished by increasing the heat capacity of the cathode or the vicinity thereof. The condensation of mercury is started first from the inner surface of the anode or the envelope, and the condensation of mercury on the cathode is prevented. At the start of lighting the next lamp, even if a lot of liquid mercury remains on the anode, it can easily shift to glow discharge as long as liquid mercury does not adhere to the cathode. is there.
[0014]
[Problems to be solved by the invention]
However, in the method for increasing the heat capacity in the vicinity of the cathode as proposed in the above publication, it is difficult to prevent the condensation of mercury on the cathode when the amount of mercury enclosed is increased. When the lamp was installed vertically so that the cathode was on the bottom and the anode on the top, it was impossible to prevent mercury from adhering to the cathode. In other words, this method makes it impossible to terminate arc discharge at a low electrode voltage during the igniter operation period, and moreover, since the amount of mercury enclosed is large, the glow after the mercury is completely depleted from above the cathode. The interelectrode voltage required for the discharge becomes higher and higher, and there is a problem that the probability of occurrence of lamp extinction increases.
[0015]
Incidentally, the vertical arrangement of the lamp is advantageous in that the devitrification phenomenon that may occur in the lamp envelope can be limited to a site that is harmless for light extraction. The installation with the anode facing upward is advantageous in that flicker is not generated, and is an important matter depending on the use conditions of the lamp.
[0016]
In view of the above-mentioned various problems, the problem to be solved by the present invention is that in a high-pressure mercury vapor lamp having a relatively large amount of mercury enclosed, the lamp completely disappears when mercury completely evaporates from the cathode. An object of the present invention is to provide a power supply device for a discharge lamp that can be prevented.
[0017]
[Means for Solving the Problems]
The present invention employs the following means in order to solve the above problems.
[0018]
A cathode and an anode are installed in a discharge space surrounded by a sealing body, a rare gas and 1 mm of the discharge space are placed in the discharge space. ³ More than 0.15mg of mercury is enclosed per When starting, it has a glow discharge state from an arc discharge state. In a discharge lamp power supply device for lighting a high-pressure mercury vapor lamp, The discharge lamp power supply apparatus includes a pseudo arc discharge resistance substantially equal to an arc discharge resistance during arc discharge of the high pressure mercury vapor lamp and a pseudo 1/7 of a glow discharge resistance during glow discharge of the high pressure mercury vapor lamp. When connecting a test circuit having a glow discharge resistance and switching from a state in which current flows through the pseudo arc discharge resistance to a state in which current flows through the pseudo glow discharge resistance, A characteristic in which a continuous period in which the pseudo glow discharge current is 30% or less of the pseudo arc discharge current is 10 μs or less, and a time until recovery to at least 70% of the pseudo arc discharge current is 100 μs or less. It is characterized by having.
[0019]
The second means is the first means, wherein the discharge lamp power supply device has a function of controlling the lamp current so that the lamp power becomes a predetermined rated power value, and a limit current value where the lamp current is predetermined. And a function of controlling the lamp current so as not to exceed the limit current value, rather than a function of controlling the lamp current so as to be the rated power value. Has a priority function, and when switching to the pseudo glow discharge resistance, there is a period of 50 ms or more that is controlled to recover to at least 70% of the pseudo arc discharge current, and this period is the rated power value. It is characterized by having a function controlled so as to allow exceeding.
[0020]
The third means is that a cathode and an anode are installed in a discharge space surrounded by a sealing body, a rare gas and 1 mm of the discharge space are placed in the discharge space. ³ More than 0.15mg mercury and 1mm per ³ 1 × 10 per ^-7 In a discharge lamp power supply apparatus for lighting a high-pressure mercury vapor lamp encapsulating a mole of halogen, an arc discharge resistance at the time of arc discharge of the high-pressure mercury vapor lamp is approximately equal to an output end of the discharge lamp power supply apparatus. The pseudo arc discharge resistance is connected to the pseudo glow discharge resistance substantially equal to the glow discharge resistance at the time of glow discharge of the high-pressure mercury vapor lamp, and the pseudo arc discharge resistance is connected to the power supply device for the discharge lamp. Then, when the pseudo glow discharge current Iag ′ when the pseudo arc discharge current is switched to the pseudo glow discharge resistance and the output voltage Vag ′ of the discharge lamp power supply device, the surface area of the cathode is Sc (mm). ² )if,
(1) Pseudo glow discharge current Iag ′ ≧ 0.14 × Sc (A) in a steady state,
(2) Output voltage Vag ′ ≧ 180 (V) in a steady state,
(3) Time τ ≦ 170 (μs) required for the output voltage Vag ′ to reach 90% of the voltage in the steady state;
It has the characteristic which becomes.
[0021]
The fourth means is any one of the first means to the third means.
The discharge lamp power supply device includes an output variable DC power source that inputs a DC voltage and applies a variable-controlled output voltage to the high-pressure mercury vapor lamp via a smoothing capacitor, and the smoothing capacitor The capacity of the smoothing capacitor is increased at the time of arc discharge transition.
[0022]
BEST MODE FOR CARRYING OUT THE INVENTION
First, a first embodiment of the present invention will be described with reference to FIGS.
[0023]
FIG. 1 is a diagram showing a temporal change in discharge current at the time of transition from arc discharge to glow discharge at the time of starting a high-pressure mercury vapor lamp and further from glow discharge to arc discharge.
[0024]
First, the principle of preventing the lamp from turning off will be described with reference to FIG.
[0025]
In a high-pressure mercury vapor lamp with a relatively large amount of mercury enclosed, when discharge starts with liquid mercury adhering to the cathode, arc discharge first appears, and the mercury on the cathode quickly evaporates. At time tg in the figure, when mercury is completely depleted from the cathode, arc discharge at a low interelectrode voltage is completed, and shift to glow discharge occurs. However, since the impedance between the electrodes rapidly increases at the time tg, the lamp current Ia tends to decrease rapidly, and the lamp goes out at this time.
[0026]
The inventors have been able to create a power supply device that does not disappear by adding various improvements to the power supply device.
[0027]
As a result of testing with a test circuit described below, it has been found that it is necessary to satisfy a predetermined condition in order to prevent the power supply apparatus from disappearing.
[0028]
First, the test circuit will be described. Figure 2 shows the volume of discharge space of a high-pressure mercury vapor lamp ³ It is a figure which shows the test circuit for finding the electric power feeder for discharge lamps used for the high-pressure mercury vapor lamp with much mercury enclosure amount in which 0.15 mg or more of mercury was enclosed per one.
[0029]
The case where the high-pressure mercury vapor lamp used in the present embodiment has an arc discharge resistance of 5Ω during arc discharge and a glow discharge resistance of 300Ω during glow discharge will be described.
[0030]
In the figure, reference numeral 2 is a discharge lamp power supply device to be evaluated for evaluating whether or not lamp extinction can be effectively prevented, and 59 and 60 are connected in series to the output terminal of the discharge lamp power supply device 2. Reference numerals 5Ω and 38Ω, 57 an FET for short-circuiting and opening the resistor 60, and 58 a gate drive circuit for switching the FET 57, respectively.
[0031]
Here, the resistor 59 has an arc discharge resistance of 5Ω during the arc discharge so that a current substantially equal to the current flowing through the resistor 59 when liquid mercury is present on the cathode of the actual high-pressure mercury vapor lamp flows through the resistor 59. The resistance 59 + the resistance 60 is set to a value equal to about 1/7 of the glow discharge resistance 300Ω during glow discharge of the high-pressure mercury vapor lamp. Here, the reason why the resistance 59 + the resistance 60 is set to a value equal to approximately 1/7 of the glow discharge resistance is to clearly determine whether or not the discharge lamp power supply device to be evaluated satisfies a predetermined condition. It is.
[0032]
In the operation of this test circuit, the FET 57 is first turned on, and only the resistor 59 is connected to simulate arc discharge when liquid mercury is present on the cathode of the high-pressure mercury vapor lamp, and then the gate By operating the drive circuit 58 to sharply turn off the FET 57 and make a transition to a state in which the resistor 59 and the resistor 60 are connected in series, the mercury is completely depleted from the cathode and the state is shifted to a glow discharge. Is to simulate. By observing the responses of these two states, it can be determined whether or not the performance of the actually manufactured discharge lamp power supply apparatus satisfies the conditions recommended by the present invention.
[0033]
Next, conditions that should be satisfied when a power feeding device that does not disappear is tested with this test circuit will be described.
[0034]
The condition will be described with reference to FIG. 1. The period Td in which the pseudo glow lamp current when the impedance of the high-pressure mercury vapor lamp suddenly increases is 30% or less of the pseudo lamp current Iao ′ immediately before the rapid increase does not exist or exists. Even if it is 10 μs or less continuously, the time Tr until the pseudo glow lamp current at the time when the impedance of the high pressure mercury vapor lamp suddenly increases is restored to at least 70% of the pseudo lamp current Iao ′ immediately before the rapid increase. Has been experimentally found that the lamp can be prevented from extinguishing when the power supply apparatus satisfies this condition. In addition, when starting lighting under such conditions, it has become clear that the lamp can be prevented from extinguishing even in the worst case where the lamp is vertically installed with the cathode down and the anode up.
[0035]
This is because when the lamp current is cut or decreased, the discharge plasma decreases and eventually disappears. However, if the lamp current is restored to a predetermined level before the discharge plasma disappears, the discharge plasma can be avoided. Therefore, in order to prevent the lamp from going out at the time of transition to glow discharge, the pseudo glow lamp current when the impedance of the high pressure mercury vapor lamp suddenly increases is 30% or less of the pseudo lamp current Iao ′ immediately before the rapid increase. The period Td is not present at all, or even if it exists, it is required to be continuously 10 μs or less.
[0036]
Even if there are a plurality of periods Td in which the pseudo glow lamp current when the impedance of the high-pressure mercury vapor lamp suddenly increases is 30% or less of the pseudo lamp current Iao ′ immediately before the sudden increase in impedance, the individual periods should be 10 μs or less. For example, it does not matter if the sum of periods exceeds that. Naturally, it is ideal that the period Td that is 30% or less does not exist. However, if the period Td is 8 μs or less, the above-described problem can be achieved with a margin, and further, 5 μs or less. More desirable.
[0037]
Further, by controlling the time Tr until the pseudo glow lamp current when the impedance of the high-pressure mercury vapor lamp suddenly increases to recover at least 70% of the pseudo lamp current Iao ′ immediately before the rapid increase is 100 μs or less, After the transition to the glow discharge, thermionic emission for quickly transitioning to the arc discharge can be activated quickly.
[0038]
Moreover, the shorter the time Tr until the pseudo glow lamp current when the impedance of the high-pressure mercury vapor lamp suddenly increases is restored to at least 70% of the pseudo-lamp current Iao ′ immediately before the rapid increase of the impedance of the high-pressure mercury vapor lamp is preferable. If the time is 80 μs or less, the above-mentioned problem can be achieved with a margin, but if it is 60 μs or less, it is more desirable. In terms of the degree of recovery of the lamp current, if the pseudo lamp current Iao ′ immediately before the sudden increase in impedance of the high-pressure mercury vapor lamp is restored to at least 85%, the problem can be achieved with a margin.
[0039]
Here, to specify the discharge lamp power supply device of the present invention using the test circuit, in order to prevent the high-pressure mercury vapor lamp from extinguishing, various elements of the discharge lamp power supply device are adjusted, This is because it is important to determine whether or not the finally changed discharge lamp power supply apparatus satisfies the predetermined condition.
[0040]
FIG. 3 is a diagram showing the pseudo lamp current Ia ′ and the pseudo lamp voltage Va ′ in the discharge lamp power supply apparatus that does not cause extinction in the test circuit shown in FIG. Here, FIG. 3A and FIG. 3B show the same phenomenon, but the time scale is different.
[0041]
FIG. 4 is a diagram showing the relationship between the pseudo lamp current Ia ′ and the pseudo lamp voltage Va ′ in the discharge lamp power supply apparatus in which the test circuit shown in FIG. is there. Here, FIG. 4A and FIG. 4B also show the same phenomenon, but the time scale is different.
[0042]
3 and 4 are subjected to an oscilloscope smoothing process for easy comparison with FIGS. 8 and 10 described later.
[0043]
As described above, by testing the discharge lamp power supply device to be evaluated using the test circuit as shown in FIG. 2, various improved discharges based on the test results as shown in FIGS. It is possible to find a discharge lamp power supply device that does not cause the lamp to disappear from the power supply device for the lamp.
[0044]
As described above, according to the present embodiment, Ra is the arc discharge resistance at the time of arc discharge of the actual high-pressure mercury vapor lamp, and Rb is the glow discharge resistance at the time of glow discharge. When a connection is made from a state in which a resistor 59 substantially equal to the arc discharge resistance Ra is connected at the end to a resistance (59 + 60) which is approximately 1/7 of the glow discharge resistance Rb, the resistor 59 is connected to the discharge lamp power supply device to be evaluated. Then, the continuous period in which the pseudo glow lamp current in the transient state where the pseudo lamp current Iao ′ is flowing to the resistance (59 + 60) is 30% or less of the pseudo lamp current Iao ′ is 10 μs or less, and The discharge lamp power supply apparatus satisfying such a condition that the time until the pseudo lamp current Iao ′ recovers to at least 70% is 100 μs or less. By using it as a power supply device for a discharge lamp of a high-pressure mercury vapor lamp, it is possible to effectively prevent the lamp from going out.
[0045]
Next, the power supply apparatus for a discharge lamp according to the present embodiment will be described with reference to FIGS.
[0046]
FIG. 5 is a diagram illustrating an example of a configuration of a discharge lamp power supply apparatus. In the figure, there are 17 DC power supplies, and the voltage from the DC power supply 17 is supplied to the step-down chopper 16. The step-down chopper 16 is mainly composed of a switch element 11, a gate drive circuit 12, a diode 13, an inductor 14, and a smoothing capacitor 15. Although the DC power source 17 is not illustrated, a commercial AC power source can be converted to a direct current using a rectifier diode, a diode bridge and a smoothing capacitor, a power module having a harmonic current suppressing function, a battery, or the like can be used. .
[0047]
Reference numeral 1 denotes a high-pressure mercury vapor discharge lamp, in which a relatively large amount of mercury is sealed in a discharge space 6 of the lamp envelope 3, and a cathode 4 and an anode 5 are arranged facing each other. 18 is a voltage detector for detecting the applied voltage Va applied to the high-pressure mercury vapor lamp 1 by using a voltage dividing resistor or the like, and 19 is a high-pressure mercury vapor lamp 1 which is constituted by a shunt resistor, CT, or the like. This is a current detector for detecting the current Ia flowing through the. 7 is an igniter that is inserted between the step-down chopper 16 and the high-pressure mercury vapor lamp 1 to cause a discharge breakdown of the sealed gas between the cathode 4 and the anode 5 when the high-pressure mercury vapor lamp 1 is turned on. Is basically constituted by a transformer 8 having a large primary to secondary winding ratio, and generates a high voltage pulse train of several kilovolts to several tens of kilovolts. A coil 9 is inserted between the step-down chopper 16 and the discharge lamp 1. A power supply control circuit 24 supplies the gate drive signal 23 to the gate drive circuit 10 of the igniter 7, and the lamp voltage signal 20 detected by the voltage detector 18 and the lamp current signal detected by the current detector 19. 21 is input, and the gate drive signal 22 is supplied to the gate drive circuit 12 of the switch element 11 based on the lamp voltage signal 20 and the lamp current signal 21 to control the opening and closing of the switch element 11.
[0048]
In the figure, an example in which the gate drive signal 23 is supplied from the power supply control circuit 24 to the gate drive circuit 10 is shown, but the igniter control signal 23 may not be necessary depending on the type of the igniter 7.
[0049]
FIG. 6 is a diagram illustrating an example of the configuration of the power feeding device control circuit 24 illustrated in FIG.
[0050]
In the figure, the detected lamp current signal 21 and the detected lamp voltage signal 20 are input to the power supply device control circuit 24 through the buffer 25 and the buffer 38 as necessary, assuming that their polarities are positive. .
[0051]
The lamp current signal 21 is input to an error integrator 31 including an operational amplifier 27 and a capacitor 30 via a resistor 26. On the other hand, the output from the limit current value signal generator 29 assumed to have a negative polarity is input to the operational amplifier 27 via the resistor 28, and the lamp current signal 21 and the limit current value signal generator 29 are output from the error integrator 31. Is integrated by the capacitor 30 and output. The output of the error integrator 31 is output as an overcurrent signal 36 via an inverter 85 including a resistor 32, a resistor 33, and an operational amplifier 34.
[0052]
On the other hand, the lamp current signal 21 is multiplied by the lamp voltage signal 20 by the multiplier 39 to generate a power signal 40, which is input via a resistor 41 to an error integrator 46 including an operational amplifier 42 and a capacitor 45. The The output from the rated power value signal generator 44 assumed to have a negative polarity is input to the operational amplifier 42 via the resistor 43, and the power signal 40 and the rated power value signal generator 44 are output from the error integrator 46. The specified power value difference is integrated by the capacitor 45 and output.
[0053]
The output of the error integrator 46 is output as an overpower signal 51 through an inverter 50 including a resistor 47, a resistor 48, and an operational amplifier 49.
[0054]
Since the current excess signal 36 and the power excess signal 51 are pulled down by the resistor 53 via the diode 37 and the diode 52, respectively, the higher one of the current excess signal 36 and the power excess signal 51 is stepped down. A chopper control signal 54 is output to the resistor 53.
[0055]
The overcurrent signal 36 is a signal that becomes high when the lamp current signal 21 is larger than the current value defined by the limit current value signal generator 29, and the overpower signal 51 is the power signal 40 when the rated power bond is It is a signal that increases when it is greater than the power value defined by the signal generator 44. Accordingly, a larger signal of the excess current signal 36 and the excess power signal appears in the resistor 53 preferentially. The step-down chopper control signal 54 is compared with the output signal of the sawtooth wave generator 55 by the comparator 56. When the step-down chopper control signal 54 is smaller than the output signal of the sawtooth wave generator 55, the high level, step-down chopper control signal When 54 is larger than the output signal of the sawtooth wave generator 55, a low level signal is output as the gate drive signal 22 to the gate drive circuit 12 of the switch element 11.
[0056]
Here, the higher the step-down chopper control signal 54, the shorter the period during which the gate drive signal 22 is at a high level. Therefore, when the gate drive signal 22 is at a high level, the gate drive circuit is turned on. If the logic of 12 is designed, the higher of the overcurrent signal 36 and the overpower signal 51, whichever is higher, which is the overcurrent signal 36, the lamp current signal 21 is the current defined by the limit current value signal generator 29. Conversely, if it is an overpower signal 51, it will be feed pack controlled so that the power signal 40 matches the power value defined by the rated power value signal generator 44. .
[0057]
As a result, the lamp current Ia is controlled so that the lamp power Pa becomes the predetermined rated power value Pas, and the lamp current Ia is controlled so that the lamp current Ia does not substantially exceed the predetermined limit current value Ias. And a function of controlling the lamp current Ia so as not to exceed the limit current value Ias over the function of controlling the lamp current Ia so as to be the rated power value Pas. The power supply device 2 can be realized.
[0058]
Specifically, in order to realize the invention according to the present embodiment, for example, the resistance 26 is set to a small resistance value and / or the capacitor 30 is set to a small capacitance value to control the limit current value Ias. The response of the error integrator 31 may be designed so as to be fast. If sufficient results are not obtained only by this, the secondary inductance of the transformer 8 of the igniter 7 may be increased, the coil 9 may be added, or both of them may be performed. Naturally, the operating frequency of the step-down chopper 16, that is, the oscillation frequency of the sawtooth wave generator 55, needs to be high enough to support the necessary high-speed control of the limit current value Ias. Further, it is advantageous to reduce the capacitance of the smoothing capacitor 15 within a range where the ripple of the step-down chopper 16 does not become excessive.
[0059]
5 and 6 are described for the purpose of explaining the basic configuration of the power supply device for a discharge lamp according to the present invention, but in order to actually realize it, if necessary, For stable operation and safe operation of the circuit, it is necessary to add an additional part such as a protection circuit and a noise filter and an additional circuit, or conversely, to simplify the circuit. In particular, the inverters 35 and 50 are intentionally added to simplify the description, and can be omitted.
[0060]
Next, a second embodiment of the present invention will be described with reference to FIGS.
[0061]
The present embodiment relates to a discharge lamp power supply apparatus to which a function for more reliably preventing the discharge lamp power supply apparatus obtained in the first embodiment from disappearing.
[0062]
In general, as shown in FIG. 7, in a mercury vapor lamp power supply device, the lamp power Pa becomes a predetermined rated power value Pas even if the lamp voltage Va fluctuates due to a change in impedance between the electrodes. Thus, the lamp current Ia is controlled. At that time, when the lamp voltage Va is very low, in order to achieve the rated power value Pas, it is necessary to flow a very large lamp current Ia. In practice, however, destruction of circuit elements provided in the power feeding device is prevented. Therefore, the lamp current Ia is controlled so that the lamp current Ia does not exceed a predetermined limit current value Ias. This control is performed with priority over the control of the lamp current Ia so that the rated power value Pas is obtained. Further, as shown in the figure, a maximum voltage value Vas is defined, but this is a limit for preventing the maximum voltage necessary for safety from being exceeded when no load is released. Therefore, the voltage-current characteristic of a general discharge lamp power supply device based on the above results is based on a hyperbola H as shown in FIG.
[0063]
8 (a), (b), and (c) are diagrams showing the time course of the lamp current Ia, the lamp voltage Va, and the lamp power Pa during this period.
[0064]
When lighting a high-pressure mercury vapor lamp with a relatively large amount of mercury enclosed in a general discharge lamp power supply device related to the present invention, the state of arc discharge when liquid mercury is present on the cathode immediately after lighting is as follows: Since the impedance between the electrodes is sufficiently low, it is considered to be at point A in FIG. This is a state in which the lamp current Ia is controlled so as not to exceed a predetermined limit current value Ias, and the rated power value is not achieved in this state. Next, when mercury completely evaporates from the cathode and shifts to glow discharge, the impedance between the electrodes increases, and the lamp voltage Va rises rapidly. Therefore, a point along the voltage-current characteristic curve H in FIG. As shown in FIG. 8A, the lamp current Ia is greatly reduced from the lamp current Iao immediately before the rapid increase in the impedance of the high-pressure mercury vapor lamp occurs. There is a possibility of disappearing.
[0065]
Therefore, in order to avoid such a state, it does not follow the voltage-current characteristic curve H of FIG. 7, but passes through a region above the voltage-current characteristic curve H, that is, an overpower region. Here, as to the conditions regarding the way of passing through the overpower region, the test circuit of FIG. 2, that is, the resistance value substantially equal to the lamp impedance at the time of arc discharge and the lamp impedance at the time of glow discharge of about 1 as in the above. It can be defined using a test circuit that switches between resistance values equal to / 7.
[0066]
FIG. 9 is a diagram showing voltage-current characteristics intended by the invention according to this embodiment.
[0067]
As shown in the voltage-current characteristic of the figure, when moving from the point A to the point B, instead of following the voltage-current characteristic curve H, the predetermined current is set in a region U of at least 70% of the pseudo lamp current Iao ′ at the point A. After staying for a time, the point B is shifted.
[0068]
FIGS. 10A, 10B, and 10C are diagrams showing time courses of the pseudo lamp current Ia ′, the pseudo lamp voltage Va ′, and the pseudo lamp power Pa ′ during this period.
[0069]
In the power supply device for a discharge lamp according to the present embodiment, the function of making the time for staying in the region U at least 70% of the pseudo lamp current Iao ′ at the point A to be 50 ms or more is added. It can be realized reliably.
[0070]
Here, in order to maintain the discharge, thermionic emission must be activated quickly. For this purpose, at least 70% of the pseudo lamp current Iao ′ immediately before the impedance of the high-pressure mercury vapor lamp rapidly increases is recovered. The longer the control period Tu is, the more advantageous in that the lamp can be prevented from extinguishing. However, if it is 70 ms or longer, the object of the present invention can be achieved with a margin, and more preferably 100 ms or longer.
[0071]
Further, since the region U of at least 70% of the pseudo lamp current Iao ′ at the point A is an overpower operation, in order to realize this, the power supply device has a predetermined rated power value Pas originally possessed. The function of controlling the pseudo lamp current Ia ′ may be added only for the time during which the pseudo lamp current Iao ′ at the point A stays in the region U at least 70% of the pseudo lamp current Iao ′. Note that this overpower operation is inherently inconvenient for the safe operation of the lamp and the power supply device, and therefore should not be continued for a longer time than necessary. In practice, 300 ms is sufficient.
[0072]
Specifically, in order to realize the invention according to this embodiment, the pseudo lamp current Ia ′ is controlled so as not to exceed the limit current value Ias by using the discharge lamp power supply device shown in FIGS. When the impedance of the high-pressure mercury vapor lamp 1 suddenly increases in the operating state, control is performed so that the pseudo lamp current Iao ′ immediately before the rapid increase of the impedance of the high-pressure mercury vapor lamp 1 recovers to at least 70%. For example, an error for controlling the rated power value Pas by setting the resistor 41 to a large resistance value and / or the capacitor 45 to a large capacitance value so that the current period Tu is 50 ms or more. This is done by designing the integrator 46 to have a slow response.
[0073]
Next, a third embodiment of the present invention will be described with reference to FIGS.
[0074]
FIG. 11 shows a discharge space of a high-pressure mercury vapor lamp with a volume of 1 mm. ³ More than 0.15mg mercury and 1mm per ³ 1 × 10 per ^-7 It is a figure which shows the test circuit for finding the electric power feeding apparatus for discharge lamps which are used for the high pressure mercury vapor lamp with a comparatively much mercury enclosure amount in which mol halogen was enclosed, and a lamp does not extinguish.
[0075]
The inventors of the present invention have found that when the discharge lamp power supply device satisfies the conditions described later by this test circuit, the discharge lamp power supply device can effectively prevent the lamp from extinguishing.
Note that the high-pressure mercury vapor lamp used in this embodiment also has an arc discharge resistance Ra during arc discharge of approximately 5Ω and a glow discharge resistance Rb during glow discharge of approximately 300Ω, as in the first embodiment. The description will be made on the premise that what is presented is used.
[0076]
In the figure, reference numerals 70 and 71 denote resistors having resistance values of 5Ω and 300Ω, respectively, connected in series to the output terminal of the discharge lamp power supply device 2, and the other configurations are the same as the configurations of the same symbols shown in FIG. Therefore, explanation is omitted.
[0077]
Here, the resistance 70 is the arc discharge resistance Ra at the time of arc discharge so that a current substantially equal to the current value flowing at the time of arc discharge when liquid mercury is present on the cathode of an actual high-pressure mercury vapor lamp flows through the resistor 70. The resistance 70 + resistance 71 are set to a value equal to the glow discharge resistance Rb so that a current that is substantially the same as the current that flows during glow discharge of the high-pressure mercury vapor lamp flows through the resistances 70 and 71.
[0078]
FIG. 12 is a diagram showing temporal changes in the pseudo lamp current Ia ′ and the pseudo lamp voltage Va ′ when the connection is switched from the state of only the resistor 70 to the series resistance of the resistor 70 and the resistor 71.
[0079]
In the present embodiment, the surface area of the cathode is Sc (mm ² ), When only the resistor 70 is connected to the output end of the discharge lamp power supply device 2 to be evaluated,
(1) Pseudo glow discharge current Iag ′ ≧ 0.14 × Sc (A) in a steady state after switching from the resistor 70 to the resistor 70 + the resistor 71,
(2) Output voltage Vag ′ ≧ 180 (V) of the discharge lamp power supply device in a steady state after switching from the resistor 70 to the resistor 70 + the resistor 71;
(3) Time τ ≦ 170 (μs) required for the output voltage Vga ′ in the steady state after switching from the resistor 70 to the resistor 70 + the resistor 71 to reach 90% of the voltage in the steady state.
It has been found that when the above conditions are satisfied, the discharge lamp power supply device 2 prevents the occurrence of extinction even when the above-described high-pressure mercury vapor lamp is used.
[0080]
Here, the surface area of the cathode is the surface area of the entire electrode having a cathode action exposed in the discharge space.
The reason why the supply capacity of the pseudo glow discharge current Iag ′ in the steady state should be increased in proportion to the surface area Sc of the cathode is different from that in the arc discharge. In the glow discharge, the discharge occurs over the entire cathode surface. This is because the electrode surface cannot be heated so that it can shift to arc discharge by thermionic emission unless it has the ability to supply a current corresponding to the cathode surface area. The supply capacity of the pseudo glow discharge current is more preferably Iag ′ ≧ 0.016 × Sc.
[0081]
At this time, the reason why the supply capacity of 180 V or more is necessary as the pseudo glow voltage Vag ′ in the steady state is that the amount of enclosed halogen in the case of a discharge lamp in which a rare gas such as mercury or argon and a halogen such as bromine are enclosed. 1mm ³ 1 × 10 per ^-7 This is because if it is at least mol, the glow discharge requires a voltage of 180 V or more regardless of the distance between the cathode and the anode, the gas pressure, and the like.
[0082]
The supply capability of the output voltage Vag ′ is more desirable if Vag ′ ≧ 200V.
[0083]
The reason why the time τ required for the output voltage Vag ′ to reach 90% of the voltage in the steady state should be 170 μs or less is that if this takes a long time, the glow discharge cannot be maintained and the discharge is stopped. After that, when the voltage is sufficiently increased, the probability that the electrode has already cooled down and eventually disappeared increases. It is more desirable that τ ≦ 100 μs.
[0084]
In the experiments by the inventors, about 25 mm under the conditions of Vag′≈200 V and τ≈100 μs. ² In the case of a lamp using a cathode having a surface area of 2 mm, the extinction rate was completely 0% by setting Iag′≈0.4 A.
[0085]
Even if the performance was reduced to Vag′≈180 V, τ≈170 μs, and Iag′≈0.35 A, the extinction rate was 1% or less, which was sufficiently practical.
[0086]
Next, a fourth embodiment of the present invention will be described with reference to FIGS.
[0087]
FIG. 13 is a diagram illustrating a configuration of a discharge lamp power supply apparatus according to the present embodiment.
[0088]
In the figure, 72 is a smoothing capacitor provided so as to be connectable in parallel with the smoothing capacitor 15, 73 is an FET for switching insertion / extraction of the smoothing capacitor 72, and 74 is a gate drive circuit for switching the FET 73. The other configurations are the same as those shown in FIG.
[0089]
FIG. 14 is a diagram showing the time course of the lamp voltage when the high-pressure mercury vapor lamp is started and lit using the discharge lamp power supply apparatus according to the present embodiment.
[0090]
In the present embodiment, as shown in FIG. 13, after the period when the impedance during the glow discharge of the lamp is large, the FET 73 is turned on in parallel with the smoothing capacitor 15 and the smoothing capacitor 72 is inserted. It increases the capacity.
[0091]
In the description of the discharge lamp power supply device shown in FIG. 5 above, it has been explained that it is advantageous to reduce the capacitance of the smoothing capacitor 15 within a range where the ripple of the step-down chopper 15 is not excessive. Keeping the capacity of the smoothing capacitor small until the transition to thermal arc discharge prevents the lamp from being damaged by suppressing the amount of charge released from the smoothing capacitor to the lamp during an instantaneous arc discharge transition, such as during glow discharge. Can do. On the other hand, if the smoothing capacitor is small, ripples are likely to occur, which causes an acoustic resonance phenomenon, and the lamp flickers or falls off.
[0092]
In view of the above problem, in the invention of the present embodiment, as shown in FIG. 14, the FET 73 is turned on after the transition to the thermal arc discharge after a period of high impedance during glow discharge, and in parallel with the smoothing capacitor 15. A smoothing capacitor 16 is connected to increase the capacity of the smoothing capacitor to prevent the lamp from flickering or extinguishing due to the acoustic resonance phenomenon.
[0093]
【The invention's effect】
According to the first aspect of the present invention, when a high-pressure mercury vapor lamp having a relatively large amount of mercury is used, the lamp is prevented from extinguishing when mercury is completely evaporated from the cathode at the beginning of lighting. be able to.
[0094]
According to the invention described in claim 2 of the present application, in addition to the effect of the invention described in claim 1, it is possible to more reliably prevent the lamp from extinguishing.
[0095]
According to the third aspect of the present invention, when a high-pressure mercury vapor lamp having a relatively large amount of mercury is used, the lamp is prevented from extinguishing when mercury is completely evaporated from the cathode at the initial stage of lighting. be able to.
[0096]
According to the invention described in claim 4 of the present application, in addition to the effects of the inventions described in claims 1 to 3, the acoustic resonance phenomenon after the transition to the thermal arc discharge after the lapse of the period when the lamp impedance is high. The lamp can be prevented from flickering or disappearing.
[Brief description of the drawings]
FIG. 1 is a diagram showing a temporal change in discharge current at the time of transition from arc discharge to glow discharge at the time of starting a high-pressure mercury vapor lamp and from glow discharge to arc discharge.
FIG. 2 is a diagram showing a test circuit for finding a discharge lamp power supply device used in the high-pressure mercury vapor lamp according to the first embodiment.
FIG. 3 is a diagram showing a pseudo lamp current I ′ and a pseudo lamp voltage V ′ in a discharge lamp power supply apparatus that satisfies predetermined conditions and does not disappear in the test circuit shown in FIG. 2;
4 is a diagram showing a pseudo lamp current I ′ and a pseudo lamp voltage V ′ in a power supply device for a discharge lamp that does not satisfy a predetermined condition and is extinguished in the test circuit shown in FIG. 2;
FIG. 5 is a diagram illustrating an example of a configuration of a discharge lamp power supply apparatus according to first and second embodiments.
6 is a diagram illustrating an example of a configuration of a power feeding device control circuit 24 illustrated in FIG. 5. FIG.
FIG. 7 is a diagram showing characteristics of a lamp current Ia and a lamp voltage Va of a high-pressure mercury vapor lamp.
FIG. 8 is a diagram showing the time course of lamp current Ia, lamp voltage Va, and lamp power Pa of a high-pressure mercury vapor lamp.
FIG. 9 is a diagram showing characteristics of a pseudo lamp current Ia ′ and a pseudo lamp voltage Va ′ of the high-pressure mercury vapor lamp according to the second embodiment.
FIG. 10 is a diagram showing a time course of pseudo lamp current Ia ′, lamp voltage Va ′, and lamp power Pa ′ of the high-pressure mercury vapor lamp according to the second embodiment.
FIG. 11 is a diagram showing a test circuit for finding a discharge lamp power supply device used in a high-pressure mercury vapor lamp according to a third embodiment.
12 is a diagram showing the characteristics of the pseudo lamp current Ia ′ and the pseudo lamp voltage Va ′ in the power supply apparatus for a discharge lamp that satisfies a predetermined condition and does not disappear in the test circuit shown in FIG.
FIG. 13 is a diagram showing a configuration of a discharge lamp power supply apparatus according to a fourth embodiment.
FIG. 14 is a diagram showing the time history of the lamp voltage Va of the high-pressure mercury vapor lamp according to the fourth embodiment.
[Explanation of symbols]
1 High-pressure mercury vapor lamp
2 Power supply device for discharge lamp
3 Envelope
4 Cathode
4a Cathode root
5 Anode
6 Discharge space
7 Igniter
8 transformer
9 Coils
10 Igniter drive circuit
11 Switch element
12 Gate drive circuit
13 Diode
14 Inductor
15 Smoothing capacitor
16 Step-down chopper
17 DC power supply
18 Voltage detector
19 Current detector
20 Lamp voltage signal
21 Lamp current signal
22 Gate drive signal
23 Igniter control signal
24 Power feeding device control circuit
25 buffers
26 Resistance
27 Operational amplifier
28 Resistance
29 Current limiting signal generator
30 capacitors
31 Error integrator
32 resistance
33 Resistance
34 Operational amplifier
35 Inverter
36 Overcurrent signal
37 diodes
38 buffers
39 Multiplier
40 Power signal
41 Resistance
42 operational amplifier
43 Resistance
44 Rated power value signal generator
45 capacitors
46 Error integrator
47 Resistance
48 resistance
49 Operational Amplifier
50 Inverter
51 Excessive power signal
52 Diode
53 Resistance
54 Step-down chopper control signal
55 Sawtooth generator
56 comparator
57 FET
58 Gate drive circuit
59 Resistance
60 resistance

Claims (4)

Is provided a cathode and an anode in a discharge space surrounded by the sealing member, in the discharge space, and a rare gas, 1 mm ³ per 0.15mg of mercury in the discharge space is sealed, at startup, the arc discharge state In a discharge lamp power supply device for lighting a high-pressure mercury vapor lamp having a glow discharge state ,
The discharge lamp power supply device includes a pseudo arc discharge resistance substantially equal to an arc discharge resistance during arc discharge of the high pressure mercury vapor lamp and a pseudo 1/7 of a glow discharge resistance during glow discharge of the high pressure mercury vapor lamp. Connect a test circuit with glow discharge resistance,
When switching from the state in which current flows through the pseudo arc discharge resistance to the state in which current flows through the pseudo glow discharge resistance,
A characteristic in which a continuous period in which the pseudo glow discharge current is 30% or less of the pseudo arc discharge current is 10 μs or less, and a time until recovery to at least 70% of the pseudo arc discharge current is 100 μs or less. A power supply device for a discharge lamp, comprising:   2. The discharge lamp power supply device according to claim 1, wherein the discharge lamp power supply device controls the lamp current so that the lamp power becomes a predetermined rated power value, and the lamp current so that the lamp current does not exceed a predetermined limit current value. And a function in which the function of controlling the lamp current so as not to exceed the limit current value is prioritized over the function of controlling the lamp current so as to achieve the rated power value. When switching to the pseudo glow discharge resistance, there is a period of 50 ms or more that is controlled to recover to at least 70% of the pseudo arc discharge current, and this period is allowed to exceed the rated power value. A discharge lamp power supply device having a function controlled by the above. A cathode and an anode are installed in a discharge space surrounded by an envelope, and in the discharge space, noble gas, 0.15 mg or more of mercury per 1 mm ^{3 of the} discharge space, and 1 × 10 ⁻⁷ mol per 1 mm ³ In a discharge lamp power supply device for lighting a high-pressure mercury vapor lamp enclosing halogen, a pseudo arc substantially equal to an arc discharge resistance at the time of arc discharge of the high-pressure mercury vapor lamp is provided at the output end of the discharge lamp power supply device. From the state where the discharge resistance is connected, the high pressure mercury vapor lamp can be switched to a pseudo glow discharge resistance substantially equal to the glow discharge resistance during glow discharge of the high pressure mercury vapor lamp, and the pseudo arc discharge resistance is connected to the discharge lamp power supply device. The pseudo glow discharge current Iag ′ and the output of the discharge lamp power supply device when the pseudo arc discharge current is switched to the pseudo glow discharge resistance. Pressure Vag 'when the, if the surface area of the cathode and ^{Sc (mm 2), (1} ) a pseudo steady-state glow discharge current Iag' ≧ 0.14 × Sc (A ), (2) the output voltage at steady state A discharge lamp characterized by: Vag ′ ≧ 180 (V), (3) Time τ ≦ 170 (μs) required for the output voltage Vag ′ to reach 90% of the voltage in the steady state. Power supply device.   4. The discharge lamp power supply device according to claim 1, wherein the discharge lamp power supply device inputs a DC voltage and applies a variably controlled output voltage to the high-pressure mercury vapor lamp via a smoothing capacitor. 5. A power supply device for a discharge lamp, comprising: a variable DC power supply, wherein the smoothing capacitor increases a capacity of the smoothing capacitor at the time of arc discharge transition after the end of glow discharge.

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