JP2008103091A - High pressure discharge lamp lighting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent occurrence of flickering by arc jump due to temperature difference between electrodes by eliminating temperature difference between lamp electrodes in a high pressure discharge lamp. <P>SOLUTION: In a high pressure discharge lamp lighting device, the AC lamp current waveform impressed on the high pressure discharge lamp is made to consist of a repetition of a waveform having as one unit a first period of a current value (+i1) and width (d1), a second period of the current value (-i2) and width (d2), a third period of the current value (+i3) and width (d3), a fourth period of the current value (-i4) and width (d4), a fifth period of the current value (+i5) and width (d5), and a sixth period of the current value (-i6) and width (d6), and (d1+d2)<d3, and (d4+d5)<d6 and at least i5, i2>i3, i6 are set, and in the fifth period, i5×d5≥i1×d1, and i5×d5>i2×d2≥i4×d4 applies. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp lighting device capable of obtaining a stable light output without shortening the life of the high pressure discharge lamp.

FIG. 1 is a circuit configuration diagram showing a conventional high-pressure discharge lamp lighting device of a general constant lamp power lighting system.
The high pressure discharge lamp lighting device includes a DC power supply unit 20 and a DC power supply unit 20 that controls a DC voltage of the DC power supply unit 10 to a predetermined lamp power by a PWM (pulse width modulation) control circuit, and the DC power supply unit 20. A full-bridge circuit 40 for converting the DC output voltage of the lamp into a low-frequency AC rectangular wave voltage and applying it to a high-pressure discharge lamp (hereinafter referred to as “lamp”) 60 and applying a high-voltage pulse voltage to the discharge lamp at the start of the discharge lamp An igniter circuit unit 50 that detects the lamp power and a control circuit unit 30 that performs constant lamp power control and constant lamp current control.

  The DC power supply unit 20 that operates by receiving the voltage of the DC power supply unit 10 includes a step-down chopper circuit that includes a switching element 21, a diode 22, a DC reactor 23, and a smoothing capacitor 24 that are driven by a PWM control circuit 36 described later. Predetermined lamp power or lamp current control is performed on the DC voltage supplied from the DC power supply circuit unit.

  Further, the control circuit unit 30 divides the voltage of the voltage dividing resistor 31c that detects the lamp voltage connected in parallel with the lamp 60 and the voltage of the resistor 32 that is connected in series with the lamp 60 and detects the lamp current. A multiplier 33 that calculates the lamp power by multiplication processing, an error amplifier 34 that compares the output terminal of the multiplier 33 and the voltage of the resistor 37 obtained by dividing the reference voltage 39, and the output of the error amplifier 34 are input. And a PWM control circuit 36 that outputs a drive pulse of the switching element 21 of the DC power supply circuit unit 20.

The PWM control circuit 36 generates a drive pulse with a duty ratio corresponding to the output of the error amplifier 34 to drive the switching element 21 of the DC power supply circuit unit 20, thereby controlling the lamp power to a predetermined value to discharge the discharge lamp. Is lit at constant lamp power or constant lamp current.
Further, when the resistor 38a that divides the reference voltage 39 of the control circuit 30 is short-circuited by the transistor 38b, the voltage of the resistance terminal 37 that becomes the reference voltage of the error amplifier 34 is increased, so that the PWM control circuit 36 has the duty of the transistor 21. The ratio is increased while the current supplied to the lamp increases. The control circuit 30 (at least the base terminal of the transistor 38b) and the bridge control circuit 45 are connected to a control means 300 such as a microcomputer.

As shown in FIGS. 8A and 8B, the transistor 38b is turned on in synchronization with the ON / OFF timings of the transistors 41 and 44 and the transistors 42 and 43, so that one cycle of the high-frequency current immediately before the low-frequency half cycle. Is applied to the lamp current waveform in which the current of one cycle or the latter half cycle is increased, and as shown in Patent Document 1, the effect of suppressing flicker due to arc spot movement of the electrode of the high-pressure discharge lamp is obtained. can get.
JP 2006-202775 A

  By the way, when the lamp 60 is lit with the lamp current waveform of FIG. 8A or FIG. 8B using the conventional high pressure discharge lamp lighting device shown in FIG. 1, the mechanism is not necessarily clear, but the lighting frequency or Depending on the lighting waveform, it is known that the electrode grows in a protruding shape as shown in FIG. 9A.

  This phenomenon is that tungsten, which is a heated electrode material, evaporates, and is combined with halogen or the like present in the arc tube to form a tungsten compound. This tungsten compound diffuses from the vicinity of the tube wall to the vicinity of the tip of the electrode by convection or the like, and is decomposed into tungsten atoms at a high temperature portion. Tungsten atoms become cations by ionizing in the arc. Both electrodes that are lit with alternating current repeat the anode and cathode at each lighting frequency, but when this cathode is operating, the cations in the arc are attracted to the cathode side by the electric field and deposited at the tips of both electrodes, It is thought that it forms a protrusion.

  However, in recent years, the size of the projector has been reduced in order to reduce the size of the projector. As shown in FIG. 2A, the air cooling means 72 outside the reflector 71 enhances the air cooling to the lamp 60 so that the lamp does not have a short life. As shown in FIG. 2B, a small reflector (secondary mirror) 73 is provided on the front side (right side in the figure) of the lamp 60 to improve the light utilization rate.

Here, when the air cooling of the lamp is increased, the front side is cooled, the temperature of the front side electrode becomes lower than that of the electrode on the neck side (left side in the figure), and there is a difference in operating temperature even though it is a pair of electrodes. End up.
In addition, when a secondary mirror is attached to the front side, the electrode is heated by the secondary mirror, and conversely the temperature of the front side electrode is higher than that of the neck side electrode. Will occur.

When the temperature of the pair of electrodes is substantially symmetric, the lamp is consumed from the tip side of the electrode while maintaining the protrusion as shown in FIG. The problem of flicker due to the arc movement of this does not occur.
However, when there is a temperature difference between the electrodes as described above, the halogen cycle of the electrode on the lower temperature side becomes insufficient, and a plurality of protrusions grow on the electrode on the lower temperature side as shown in FIG. 9C. There is a problem that the surface of the electrode is temporarily roughened and flicker due to arc jump is likely to occur.

  The present invention has been made to solve the above-described problems in the conventional discharge lamp lighting device, and when the temperature difference between a pair of electrodes becomes large when lighting with a symmetrical current waveform, the electrode temperature is lower. A discharge lamp lighting device in which the width of a high-frequency rectangular wave current having a value larger than the low-frequency rectangular wave current inserted immediately before the half-cycle of the low-frequency rectangular wave during anode operation is increased or the height is increased. The purpose is to provide.

A first aspect of the present invention includes a DC power supply unit that receives a DC voltage and outputs a DC current, a full bridge circuit that converts the DC current into an AC voltage and supplies an AC lamp current to a high-pressure discharge lamp, and a DC power supply unit And a control circuit for controlling the switching operation of the full bridge circuit, and the AC lamp current waveform has a current value (−i2) during a first period of current value (+ i1) and width (d1). The second period of width (d2), current value (+ i3), the third period of width (d3), the current value (−i4), the fourth period of width (d4), the current value (+ i5) A DC current value and a switching operation by the control circuit so as to consist of repetition of a waveform having a fifth period of width (d5) and a sixth period of current value (−i6) and width (d6) as one unit. Are controlled and at least (d1 + d2 <D3 and (d4 + d5) <d6, and in the high pressure discharge lamp lighting device set as i5, i2> i3, i6, the high pressure discharge lamp has first and second electrodes, When the current flowing from one electrode to the second electrode is equal to the current in the opposite direction and the temperature of the first electrode is lower than that of the second electrode, the AC lamp current (i1 to i6) ) Is defined as the direction from the first electrode to the second electrode, and for the fifth period, i5 × d5 ≧ i1 × d1 and i5 × d5> i2 × d2 ≧ i4 This is a high pressure discharge lamp lighting device configured to be xd4.
Furthermore, regarding the fifth period, d5 ≧ d1 and d5> d2 ≧ d4 may be satisfied, or i5 ≧ i1 and i5> i2 ≧ i4 may be satisfied.

According to a second aspect of the present invention, there is provided a high pressure discharge lamp lighting device according to the first aspect, a high pressure discharge lamp having first and second electrodes to which an AC lamp current is supplied from the high pressure discharge lamp lighting device, and a high pressure discharge. It is a light source device provided with the reflector to which an electric lamp is attached.
Here, cooling means for cooling the high pressure discharge lamp is further provided, and the first electrode is installed on the front side of the reflector, and the second electrode is installed on the neck side of the reflector.
Further, the apparatus further comprises a secondary mirror attached to the high-pressure discharge lamp, the first electrode is installed on the neck side of the reflector, the second electrode is installed on the front side of the reflector, and the secondary mirror is the second mirror. It was set as the structure attached to the electrode vicinity.

  According to the present invention, in the conventional lamp current waveform that is supposed to have an effect of preventing flicker, the current waveform flowing through the lamp is asymmetrical as necessary to eliminate the temperature difference between the electrodes of the lamp. The occurrence of flicker due to an arc jump due to a temperature difference between the lamp electrodes that has not been noticed can also be effectively prevented.

Example 1.
An embodiment of the present invention will be described in comparison with a conventional example.
In this embodiment, the circuit configuration diagram is the same as that of FIG. 3A and 3B are lamp current waveforms and transistor operation diagrams showing an embodiment of a high pressure discharge lamp lighting device according to the present invention. In this specification, the current value means an average value in so-called low frequency periods T3 and T6 and a peak value in high frequency periods T1, T2, T4 and T5.

  More specifically, one unit of the lamp current waveform in the present invention is composed of six periods T1 to T6 as shown in FIG. Note that the period T1 is a current value (+ i1) / width (d1), the period T2 is a current value (−i2) / width (d2), the period T3 is a current value (+ i3) / width (d3), and the period T4 is a current value. (−i4) · width (d4), period T5 is current value (+ i5) · width (d5), and period T6 is current value (−i6) · width (d6). If one unit from the period T1 to T6 is one cycle, the frequency is about 60 Hz to 1 KHz. The width (d1 + d2 + d4 + d5) :( d3 + d6) is about 1:20 to 1: 4.

  The currents in the periods T3 and T6 are dominant to the effective lamp current when the rated steady lighting of the lamp is performed. Therefore, (d1 + d2) << d3 and (d4 + d5) << d6, and d3≈d6 and i3≈i6 in order to make the lamp power substantially constant. The absolute values of i3 and i6 are determined according to the required lamp power. The periods T2 and T5 are the most dominant currents for flicker suppression as shown in the prior art. Similarly, the periods T3 and T6 are dominant currents after the periods T2 and T5 for flicker suppression. Therefore, as in Patent Document 1, at least i2, i5> i3, i6.

  Here, in this embodiment, the electrode on the low temperature side such as the front electrode shown in FIG. 2A or the neck electrode shown in FIG. As shown in the graph, the current toward the side electrode is defined as the positive side of the graph), at least the width d5 of the period T5 or the widths d5 and d1 of the periods T5 and T1 are increased, and the low temperature side electrode to the high temperature side electrode Increase the energy of the current that goes. That is, in FIG. 2A, the width of the current from the front side electrode to the neck side electrode (current in the left direction in the figure) is made larger than the width of the current flowing in the opposite direction, while in FIG. The width of the current (current to the right in the figure) from the first to the secondary mirror side electrode is made larger than the width of the current flowing in the opposite direction.

Thus, by widening the current width from the electrode on the low temperature side, the electrode temperature rises, the temperature difference between the two electrodes disappears, both become the optimal halogen cycle, and the electrode is consumed while maintaining the protrusion as shown in FIG. 9B. Therefore, flicker due to arc jump can be prevented.
The period T5 has an effective action for preventing flicker by eliminating the temperature difference between the electrodes, but also for preventing flicker when the temperature difference disappears, so the current value (current height) of each period is relative. On the premise that the relationship is constant, the increase in the current width in the period T5 is most effective for bringing out both effects.
Therefore, if the magnitude relation of the current width is specified, d5 = d1> d2 = d4 in FIG. 3A and d5> d1 = d2> d4 in FIG. 3B, but d5 is the largest and d4 is the smallest. , D1 is d2 or more, d1, d2, d4, and d5 can be appropriately selected.

Example 2
In the first embodiment, the energy of each period is adjusted by changing the current width. However, in this embodiment, the energy of each period is adjusted by changing the current value.
FIG. 5 is a circuit configuration diagram showing another embodiment of the present invention. The same or corresponding members as those in the first embodiment shown in FIG. The high pressure discharge lamp lighting device according to the present invention is different from the first embodiment in that a resistor 38C and a transistor 38d are newly connected between the reference voltage 39 of the control circuit 30 and the error amplifier 34, and the base terminal of the transistor 38d. Is also connected to the control means 300. When the transistor 38d is turned on at the same time as the transistor 38b, the voltage at the end of the resistor 37, which is the reference voltage of the error amplifier 34, further increases, so that the current values i1 and i5 in the periods T1 and T5 in FIG. 6A and the period in FIG. The current value i5 of T5 can be further increased.

  6A or 6B (from the low temperature side electrode to the high temperature side) when the anode is operating, such as the front side electrode shown in FIG. 2A or the neck side electrode shown in FIG. Current flowing toward the electrode is set to the positive side of the graph), at least the current value i5 in the period T5 or the current values i5 and i1 in the periods T5 and T1 are increased, and the current flowing from the low temperature side electrode to the high temperature side electrode Increase the value. That is, in FIG. 2A, the current value of the current from the front side electrode to the neck side electrode (current in the left direction in the figure) is made larger than the current value flowing in the opposite direction, while in FIG. The current value of the current (rightward current in the figure) from the first to the secondary mirror side electrode is made larger than the current value flowing in the opposite direction.

In this way, by increasing the current value from the electrode on the low temperature side, the electrode temperature rises, the temperature difference between the two electrodes disappears, both become the optimal halogen cycle, and the electrode maintains the protrusion as shown in FIG. 9B. Since it is consumed, flicker due to arc jump can be prevented.
Similarly to the first embodiment, the period T5 has an effective action for preventing flicker by eliminating the temperature difference between the electrodes and for preventing flicker when the temperature difference disappears. The increase in the current value in the period T5 is most effective for bringing out both effects under the assumption that the general relationship is constant.
Therefore, if the magnitude relationship between the current values is specified, i5 = i1> i2 = i4 in FIG. 6A and i5> i1 = i2> i4 in FIG. 6B, but i5 is the largest and i4 is the smallest. , I1 is equal to or greater than i2, i1, i2, i4 and i5 can be appropriately selected.

In the first embodiment, the current width in a specific period is increased, and in the second embodiment, the current value is increased. As can be seen from the above, the period T5 has an effective action for preventing flicker by eliminating the temperature difference between the electrodes and for preventing flicker when there is no temperature difference. It turns out that it is the most effective for extracting the effect.
Therefore, if the current energy is defined as current value × energization time, the conventional waveform in FIG. 8A may be changed so that i5 × d5 = i1 × d1> i2 × d2 = i4 × d4. The waveform of FIG. 8B may be changed so that i5 × d5> i1 × d1 = i2 × d2> i4 × d4. In summary, if i5 × d5 is the largest, i4 × d4 is the smallest, and i1 × d1 is greater than or equal to i2 × d2, i1 × d1, i2 × d2, i4 × d4, and i5 × d5, Thus, it is possible to bring out both the effects of eliminating the temperature difference between the electrodes related to each other and suppressing the flicker. In addition, FIG. 4 used for description of each period (T1-T6) is an example which changed both the electric current value i and the electric current width d.

  In the control according to the present invention, constant lamp current control or constant lamp power control is performed. Therefore, even if the width and height of the high-frequency current portion are increased, the effective value current or the effective lamp power value is almost the rated value. Since this control does not apply more stress than necessary to the lamp electrodes, this control does not shorten the lamp life.

  In the first and second embodiments, the control circuit 30 is mainly composed of an analog circuit for clarity of explanation, but a part or all of the control circuit 30 and the control means 300 may be composed of a microcomputer. . Specifically, at least a lamp voltage value (voltage of the resistor 31c) and a lamp current value (voltage of the resistor 32) are input to the microcomputer, and a control signal to the bridge control circuit 45 and a control signal to the PWM control circuit 36 are received. Any configuration may be used as long as it is output.

Example 3
In the first and second embodiments, the high pressure discharge lamp lighting device capable of obtaining a stable light output without shortening the lifetime while suitably preventing flicker is shown. However, a light source device as an application using the high pressure discharge lamp is shown. As shown in FIG.
In FIG. 7, 74 is the high pressure discharge lamp lighting device described above, and 75 is a housing containing the high pressure discharge lamp lighting device 74, the lamp 60 and the reflector 71 as required. In addition, the figure is a schematic illustration of the embodiment, and the dimensions, arrangement, and the like are not as illustrated. 2A, an air cooling means 72 may be provided outside the reflector 71, or a secondary mirror 73 may be attached to the lamp 60 as shown in FIG. 2B. Although the air cooling means 72 is shown as an optimal example of the cooling means of the lamp (or reflector), other cooling means such as a heat radiating means such as a heat sink may be used. Furthermore, a projector can be configured by appropriately arranging a video system member or the like (not shown) in the housing 75.

  As described above, since the high-pressure discharge lamp lighting device capable of obtaining a stable light output without shortening the lifetime while preventing flicker is built in, a light source device with improved optical characteristics and lifetime characteristics can be obtained.

In addition, although the said Example was shown as the most suitable example of this invention, the following is noted in connection with it.
(1) In the above embodiment, the lamp current in the low frequency periods T3 and T6 has been described as a rectangular wave. However, the rectangular wave in the periods T3 and T6 referred to in the present invention is a waveform that is not strictly rectangular, for example, a waveform in which another current waveform is superimposed on the rectangular wave, or a part of the rectangular wave is depressed. A waveform or a waveform having different current values at the start and end of one period T3 or T6 is also included.
(2) In the above embodiment, the lamp current in the high frequency periods T1, T2, T4, and T5 has been described as a rectangular wave. However, the rectangular wave in the periods T1, T2, T4 and T5 referred to in the present invention is a waveform that is not strictly rectangular, for example, a rectangular wave is an impedance of a circuit (in particular, an inductance component of a pulse transformer used in an igniter circuit). Waveform that is distorted due to switching or a waveform in which the vicinity of the peak is broken due to the influence of the switching operation is also included.

The circuit block diagram which shows the 1st Example of this invention. The figure explaining the 1st and 2nd Example of this invention. The figure explaining the 1st and 2nd Example of this invention. The figure which shows each part waveform of the 1st Example of this invention. The figure which shows each part waveform of the 1st Example of this invention. The figure explaining the 1st and 2nd Example of this invention. The circuit block diagram which shows the 2nd Example of this invention. The figure which shows each part waveform of the 2nd Example of this invention. The figure which shows each part waveform of the 2nd Example of this invention. The figure which shows the light source device of the 3rd Example of this invention. The figure which shows each part waveform of a prior art example. The figure which shows each part waveform of a prior art example. The figure which shows the electrode of the lamp | ramp with which the processus | protrusion grew. The figure which shows the electrode in the lifetime of the lamp | ramp whose electrode temperature is object. The figure which shows the electrode in the life of the lamp | ramp whose electrode temperature is not object.

Explanation of symbols

10. DC power supply unit 20. DC power supply circuit unit 21. Transistor 22. Diode 23. DC reactor 24. Capacitor 30. Control circuit unit 31a. Zener diodes 31b, 31c, 32. Resistor 33. Multiplier 34. Error amplifier 35. Integration circuit 36. PWM control circuits 37, 38, 38a, 38c. Resistors 38b, 38d. Transistor 39. Reference voltage 40. Full bridge circuits 41-44. Transistor 45. Bridge control circuit 50. Igniter circuit section 60. High pressure discharge lamp
71. Reflector 72. Air cooling means 73. Secondary mirror 74. High pressure discharge lamp lighting device 75. Housing 300. Control means

Claims (6)

A DC power supply unit that receives a DC voltage and outputs a DC current; a full bridge circuit that converts the DC current into an AC voltage to supply an AC lamp current to a high-pressure discharge lamp; and a DC current value output by the DC power supply unit; A control circuit for controlling the switching operation of the full bridge circuit;
The AC lamp current waveform includes a first period of current value (+ i1) and width (d1), a second period of current value (−i2) and width (d2), and a current value (+ i3) and width (d3). The third period, the fourth period of the current value (−i4) · width (d4), the fifth period of the current value (+ i5) · width (d5), and the current value (−i6) · width (d6). ), The direct current value and the switching operation are controlled by the control circuit so as to consist of repetition of a waveform having the sixth period as one unit,
(D1 + d2) <d3 and (d4 + d5) <d6,
In the high pressure discharge lamp lighting device set as i5, i2> i3, i6,
When the high-pressure discharge lamp has first and second electrodes, and the current flowing from the first electrode toward the second electrode is equal to the current in the opposite direction, the first electrode When the temperature is lower than that of the second electrode, the (+) direction of the alternating lamp current (i1 to i6) is defined as the direction from the first electrode to the second electrode,
For the fifth period,
i5 × d5 ≧ i1 × d1 and i5 × d5> i2 × d2 ≧ i4 × d4
A high pressure discharge lamp lighting device characterized by In the high pressure discharge lamp lighting device according to claim 1, further about the fifth period,
d5 ≧ d1 and d5> d2 ≧ d4
High pressure discharge lamp lighting device. In the high pressure discharge lamp lighting device according to claim 1, further about the fifth period,
i5 ≧ i1 and i5> i2 ≧ i4
High pressure discharge lamp lighting device.   The high pressure discharge lamp lighting device according to any one of claims 1 to 3, a high pressure discharge lamp having first and second electrodes to which an AC lamp current is supplied from the high pressure discharge lamp lighting device, and the high pressure A light source device including a reflector to which a discharge lamp is attached. The light source device according to claim 4, further comprising cooling means for cooling the high-pressure discharge lamp,
A light source device in which the first electrode is installed on the front side of the reflector and the second electrode is installed on the neck side of the reflector. The light source device according to claim 4, further comprising a sub mirror attached to the high pressure discharge lamp,
A light source device in which the first electrode is installed on the neck side of the reflector, the second electrode is installed on the front side of the reflector, and the secondary mirror is attached in the vicinity of the second electrode.

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