JP2008270058A - High pressure discharge lamp lighting device, projector and lighting method of high pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high pressure discharge lamp lighting device of which the lifetime is improved by suppressing flickering, and to provide a lighting method of the high pressure discharge lamp. <P>SOLUTION: A first aspect of the present invention is a lighting method of the high pressure discharge lamp in the high pressure discharge lamp lighting device composed of a power supply means in order to supply an AC current to the high pressure discharge lamp, and a control means for controlling operation of the power supply means. The control means consists of a step of applying a refreshing lighting mode which is a lighting mode in order to melt a projection grown more than required at the electrode tip of the high pressure discharge lamp or the projection precipitated except the projectionfor a predetermined period of time after lighting the lamp, and a step of applying a normal lighting mode which is the lighting mode in which the projection is easy to be grown or maintained at the electrode tip of the high pressure discharge lamp after passage of a predetermined time. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp lighting device, a projector and a high pressure discharge lamp lighting method for supplying an alternating lamp current to light a high pressure discharge lamp.

  A high pressure discharge lamp lighting device used for a liquid crystal projector or the like is configured to convert a current supplied from a direct current power source into an alternating current of about 1 kHz or less, and to turn on the high pressure discharge lamp while switching the lighting polarity. Here, the high-pressure discharge lamp is a high-pressure mercury lamp (hereinafter referred to as “lamp”), in which a halogen substance, a rare gas, and mercury are enclosed, and a pair of electrodes are disposed facing each other in the arc tube.

  By the way, it is known that when the lamp is continuously lit with the alternating current as described above, a so-called flicker is generated in which the starting point of the discharge arc jumps on the electrode tip. This is because as the lighting time progresses, the tip of the electrode becomes rough as shown in FIG. 10, and the starting point of the discharge arc moves along the plurality of protrusions at the tip of the electrode and cannot be fixed at one point.

In order to suppress this flicker, a countermeasure by supplying a current having a special waveform to the lamp has been reported so far. For example, in Patent Document 1, as an AC lamp current, one cycle of a high frequency current is inserted between half cycles of a low frequency rectangular wave current as a base, and the latter half cycle or one cycle of the high frequency portion is the low frequency portion. What makes it larger than an electric current is disclosed (refer FIG. 6 (a), (b), respectively). In FIG. 6, t _{a to} t _b are one whole cycle, and the period T _HF is one cycle of the high frequency current period. Then, by lighting with such a current waveform, one projection as shown in FIG. 3B, for example, grows at the tip of the lamp electrode, and the flicker is suppressed by setting the starting point of the arc at the projection. Is.

In addition to the waveforms shown in FIG. 6, various lamp current waveforms for forming various protrusions have been reported. For example, Patent Document 2 discloses a technique in which a pulse current is superimposed at the end of a half cycle based on a low-frequency rectangular wave current as shown in FIG.
Further, in Patent Document 3, as shown in FIG. 11B, a lamp current whose current gradually increases from the start to the end in the half cycle based on the low-frequency rectangular wave current. A waveform is disclosed.

  However, when the current having the waveform as described above is used, it has been confirmed that protrusions that can be the starting point of the discharge arc are grown on the electrode. However, when lighting is continued thereafter, FIG. Through this state, it has been found that other protrusions are also formed around the protrusions as shown in FIG. 3E, and the above-described flicker problem due to the plurality of protrusions may not be solved.

Further, Patent Document 4 discloses that an electrode surface repair period is provided to repair the occurrence of a plurality of protrusions due to rough electrode surfaces. According to this, there is shown a method of intermittently providing a period in which the lamp current is equal to or higher than the rated current or a period in which the lighting frequency is equal to or lower than 5 Hz at a predetermined time during lamp lighting (in the case of AC lighting) for 1 second or longer Yes. The effect of this repair period is to uniformly heat the electrode surface and eliminate a plurality of problematic protrusions. The document also suggests that the electrode surface repair period may be provided before the lamp reaches stable lighting.
JP 2006-202775 A Japanese National Patent Publication No. 10-501919 Japanese Patent Laid-Open No. 2003-243195 Patent No. 3840054

  The present invention is particularly directed to a high pressure discharge lamp lighting device for a projector. Therefore, it is important to consider the device control method. First, it is necessary not to give a sense of incongruity to the user's vision when the content is shown, that is, consideration must be given to the user's vision.

  Here, in Patent Document 4, the electrode surface repair period is intermittently provided during stable lighting, but in Patent Document 4, the lighting frequency during the repair period is 5 Hz or less, or a lamp current greater than the rated current is applied. Therefore, if the control is performed according to the repair period at the time of stable lighting (particularly during the screening of the content), there is a possibility that the user's vision may be uncomfortable. In particular, in the case of the AC lighting type, if the lighting frequency is lower than 50 Hz, the polarity inversion of the lamp current itself can be visually recognized as flickering, which is uncomfortable for the user. Therefore, the countermeasure according to this document cannot be said to be a suitable countermeasure from a visual viewpoint.

In addition, as shown in the same document, even when the electrode surface repair period is provided before stable lighting, lighting with a very low lighting frequency of 5 Hz or less is a match with the viewpoint of circuit design and the lamp. From the viewpoint of
Regarding problems in circuit design, a general-purpose full bridge driver IC is generally used as a bridge control circuit from the viewpoint of reducing the number of parts, reducing costs, standardizing parts, and the like. However, since the general-purpose driver IC is not designed assuming a low frequency of about 5 Hz, reliability cannot be ensured in such use. Further, if a driver circuit is configured with discrete parts without using a general-purpose driver IC, or if a dedicated driver IC is used, a significant increase in cost is inevitable.

  Also, when matching with the lamp, when lighting at a very low lighting frequency such as 5 Hz or less, since the time for one electrode as an anode per time is too long, the temperature of the entire electrode rises more than necessary. End up. As a result, the entire electrode is damaged and consumed beyond the original purpose of dissolving the protrusions. Furthermore, in the case of quasi-direct current lighting at an extremely low frequency of 1 Hz or less, it is difficult to exert an effect equally on both the pair of electrodes. Therefore, even if the countermeasure according to this document is effective for a specific lamp, it cannot be said that it is suitable for a general lamp.

  A first aspect of the present invention is a lighting method of a high pressure discharge lamp in a high pressure discharge lamp lighting device comprising power supply means for supplying an alternating current to the high pressure discharge lamp and control means for controlling the operation of the power supply means. In the control means, a refresh lighting mode, which is a lighting mode for dissolving projections grown more than necessary on the electrode tip of the high-pressure discharge lamp or projections other than the projections, is applied in a predetermined period after the lamp is lit. This is a lighting method comprising a step and a step of applying a normal lighting mode, which is a lighting mode in which protrusions easily grow or maintain at the electrode tip of the high-pressure discharge lamp after a predetermined time has elapsed.

  In the first aspect, the frequency of the alternating current is set to 10 Hz to 1 kHz, the frequency fr in the refresh lighting mode is set lower than the frequency fn in the normal lighting mode, and the frequency fr is set to fr <75 Hz.

  In the first aspect, when the current value in the refresh lighting mode is a voltage range in which the lamp voltage of the high-pressure discharge lamp is less than the lower limit value of the rated lamp voltage range, the lower limit value of the rated lamp voltage range of the high-pressure discharge lamp The value was larger than the current value at.

  In the first aspect, the power value in the refresh lighting mode is set to a value larger than the rated lamp power of the high pressure discharge lamp.

  Furthermore, in the first aspect, the current waveform in the refresh lighting mode is a substantially rectangular wave, and the current waveform in the normal lighting mode is a waveform in which protrusions are likely to grow at the electrode tip of the high pressure discharge lamp.

  A second aspect of the present invention is a high pressure discharge lamp lighting device comprising power supply means for supplying an alternating current of 10 Hz to 1 kHz to a high pressure discharge lamp, and control means for controlling the operation of the power supply means. The control means operates the power supply means with the lighting frequency fn when the high-pressure discharge lamp is stably lit, and the power is supplied with the lighting frequency fr lower than the lighting frequency fn during the period after the start of discharge of the high-pressure discharge lamp and before reaching the stable lighting. The high-pressure discharge lamp lighting device is configured to operate the supply means and has fr <75 Hz ≦ fn with respect to the lighting frequencies fn and fr.

  A third aspect of the present invention is a high pressure discharge lamp lighting device comprising power supply means for supplying an alternating current to a high pressure discharge lamp, and control means for controlling the operation of the power supply means. If the lamp voltage is less than the lower limit value of the rated lamp voltage range after the start of discharge and before stable lighting is reached, and the current value is lower than the lower limit value of the rated lamp voltage range of the high-pressure discharge lamp This is a high pressure discharge lamp lighting device in which the control means is configured so that the power supply means outputs the current value.

  A fourth aspect of the present invention is a high pressure discharge lamp lighting device comprising power supply means for supplying an alternating current to a high pressure discharge lamp, and control means for controlling the operation of the power supply means. If the lamp voltage is less than the lower limit of the rated lamp voltage range after the start of discharge and before stable lighting is reached, the power supply means will output power that is greater than the rated lamp power of the high-pressure discharge lamp. This is a high pressure discharge lamp lighting device in which the control means is configured.

  According to a fifth aspect of the present invention, there is provided a high pressure discharge lamp lighting device, a high pressure discharge lamp, a reflector to which the high pressure discharge lamp is attached, and a housing containing the high pressure discharge lamp lighting device and the reflector. It is a projector provided.

  According to the present invention, unnecessary protrusions grown on the electrode of the lamp can be dissolved by the refresh lighting mode, so that occurrence of lamp flicker can be suppressed.

  Further, since the refresh lighting mode is activated at the timing of starting the lamp (at the time of lamp rising) and the refresh lighting mode is performed during a period when the light output of the lamp is not sufficient, there is no visual discomfort to the user.

  Furthermore, in the normal lighting mode that occupies most of the lighting period, a lamp current waveform suitable for securing the lamp life can be used as the lamp current, so that the present invention also contributes to securing the lamp life. Furthermore, since the light is lit at a reasonable frequency even during the refresh lighting mode, there is no damage to the electrodes during this period.

  In addition, because it is possible to design a circuit within the performance range of a general-purpose driver IC, etc., using such a general-purpose IC makes it possible to make an inexpensive device with a small number of parts and lighting of other high-pressure discharge lamps such as different rated outputs. Equipment and parts can be shared (standardized), which is preferable for production management.

<Outline of the present invention>
FIG. 1 is a circuit configuration diagram of the present invention. 1 will be described below. The high pressure discharge lamp lighting device of the present invention includes a full-wave rectifier circuit 10, a step-down chopper circuit 20 that controls a DC voltage of the full-wave rectifier circuit 10 to a predetermined lamp power or lamp current by a PWM (pulse width modulation) control circuit, and a step-down chopper circuit 20 A full bridge circuit 40 for converting the DC output voltage of the chopper circuit 20 into an AC rectangular wave current and applying it to the lamp 60, an igniter circuit 50 for applying a high voltage pulse voltage to the lamp at the start of the lamp, and the step-down chopper circuit 20 And a control circuit 30 for controlling the full bridge circuit 40. In order to make the drawing easy to see, a full-wave rectification / capacitor input type circuit is shown as the rectifier circuit 10, but a booster circuit (power factor correction circuit) or the like is included as necessary.

  The step-down chopper circuit 20 includes a transistor 21, a diode 22, a choke coil 23, and a smoothing capacitor 24 that are PWM-controlled by a PWM control circuit 34. A DC voltage supplied from the full-wave rectifier circuit 10 is converted into predetermined lamp power or lamp. Controlled to convert to current. The full bridge circuit 40 is controlled by the bridge control circuit 45 so that the pair of transistors 41 and 44 and the pair of transistors 42 and 43 are alternately turned on / off at a predetermined frequency. As a result, an alternating current (basically a rectangular wave) is applied to the lamp 60. The lamp 60 is assumed to have a rated power of about 50 to 400 W. The value of the predetermined lamp power or lamp current and the predetermined frequency are determined by the central control unit 35 in the control circuit 30. In addition, the constant lamp control can use the detection lamp current by the resistor 33 and the constant power control can use the detection lamp voltage and the detection lamp current multiplied by the resistors 31 and 32 as needed in the central control unit 35. it can.

  The lighting mode of the present invention includes two modes, a normal lighting mode and a refresh lighting mode. The normal lighting mode is a lighting mode for forming a protrusion on the electrode tip of the lamp. The refresh lighting mode is a lighting mode for melting an unnecessary protrusion at the tip of the electrode to make the electrode surface in a preferable state when the lamp is started. Details of each mode will be described later.

FIG. 3 shows the state of the electrode surface at each step, and FIG. 4 is a timing chart.
When the power to the high pressure discharge lamp lighting device is turned on, the lighting device is started lamp 60 is started lighting operation (corresponding to t ₀ in FIG. 4). A general start control may be used for this start control, and since it is not the essence of the present invention, the description is omitted. Assuming that this point is the initial state of the lamp, a projection is usually formed at the electrode tip of the lamp as shown in FIG.

  It is possible to some extent to maintain and grow the projection at the tip of the electrode by lighting the high-pressure discharge lamp using the conventional techniques described so far. However, when the accumulated lighting time of the high-pressure discharge lamp becomes long and the middle stage of the lamp life is passed, recrystallization of the electrode starts, and the composition of the tungsten changes to make it difficult for the evaporated tungsten to return to the original protrusion. As a result, when the lighting in the normal lighting mode using the conventional technique is continued, protrusions gradually start to form in places other than the original protrusions, resulting in a state as shown in FIG.

  If the lamp is kept on in the normal lighting mode in the state of the electrode as shown in FIG. 3E, the newly formed protrusion will eventually grow, eventually reaching the state as shown in FIG. Jumps on the plurality of protrusions, that is, flicker occurs.

  In order to suppress the occurrence of flicker due to the growth of the plurality of protrusions, when the high-pressure discharge lamp lighting device starts operating, first, lighting is performed in the set start-up refresh lighting mode. That is, the control circuit 30 controls the step-down chopper circuit 20 and the full bridge circuit 40 with the output current and frequency for the refresh lighting mode, and continues the refresh lighting mode until a predetermined time elapses. That is, every time the lamp is lit by the high pressure discharge lamp lighting device, lighting is performed in the refresh lighting mode for a predetermined period to dissolve unnecessary protrusions at the electrode tip.

  In step S102 shown in FIG. 2, the protrusion at the electrode tip is dissolved, and there is almost no protrusion as shown in FIG. 3C, or the electrode tip is flat as shown in FIG. However, when the predetermined time has elapsed, the high pressure discharge lamp lighting device is switched to lighting in the normal lighting mode. That is, the control circuit 30 controls the step-down chopper circuit 20 and the full bridge circuit 40 to the output current and frequency for the normal lighting mode. By lighting in the normal lighting mode, a new protrusion is formed and grows at the tip of the electrode, and the lamp 60 is stably lit.

Hereinafter, “lighting mode” and “predetermined period” will be described.
<Lighting mode>
The normal lighting mode is determined as follows.
The purpose of the normal lighting mode is so-called stable lighting. That is, the lamp current conditions for the normal lighting mode are as follows: (1) the protrusion at the tip of the electrode tends to grow (flicker suppression), and (2) the polarity reversal of the AC lamp current is not visible (flicker). Avoidance), (3) no standing wave is generated in the bulb of the lamp (acoustic resonance phenomenon avoidance), (4) brightness, that is, lamp power or current is a rated value, and (5) lamp life. It is required to satisfy that the waveform is a proven waveform from the viewpoint of ensuring. Conditions (2) and (3) depend on the lighting frequency, the lighting frequency satisfying condition (2) is 50 Hz or more, and the lighting frequency satisfying condition (3) is 1 kHz or less. In order to satisfy the condition (5), it is desirable that the waveform is a rectangular wave having a track record in practical use. In consideration of future performance, it is possible to use waveforms as shown in FIG. 6 and FIG. 11 (a) or (b), but in the following description, we focus on standard rectangular waves. I will explain. Then, on the premise that the condition (4) is followed, the only element to be examined to satisfy the condition (1) is the lighting frequency.

  Here, the relationship between the lighting frequency and the growth and dissolution of the protrusions at the tip of the electrode is shown in FIG. According to the experiments by the inventors, it has been found that at the lighting frequency of 50 Hz to 1 kHz, the protrusion tends to grow on the high frequency side and melt on the low frequency side around 75 Hz. Assuming that the lighting frequency that becomes the boundary between the growth tendency and the dissolution tendency is fb, fb is around 75 Hz from the experiment results of the inventors. Accordingly, the lighting frequency fn in the normal lighting mode is determined as fb <fn ≦ 1 kHz. However, since the value of the frequency fb varies, in setting the actual frequency fn, it is desirable that fb is regarded as a wide frequency band and a frequency sufficiently separated from fb is used.

  In summary, the lamp current in the normal lighting mode is determined to be a rectangular wave rated current whose lighting frequency exceeds fb and is 1 kHz or less.

The refresh lighting mode is determined as follows.
The purpose of the refresh lighting mode is to dissolve the protrusions at the tip of the electrode. That is, as a condition of the lamp current for the refresh lighting mode, (1) it is an essential condition that the protrusion at the tip of the electrode is in a melting tendency. In addition, when the refresh lighting mode is considered to be applied during normal lighting, (2) polarity inversion of the AC lamp current is not visually recognized (flicker avoidance), and (3) standing waves are generated in the lamp bulb. It is necessary to satisfy the conditions that they do not occur (avoidance of acoustic resonance phenomenon) and (4) brightness, that is, lamp power or current is a rated value. However, the refresh lighting mode in the present invention is applied at the time of starting the lamp, which is a condition in which the polarity inversion of the AC lamp current is difficult to be visually recognized because the light output of the lamp is still insufficient. . In addition, arc fluctuations due to standing waves in the lamp bulb are also difficult to visually recognize. In other words, during this period, since the light output of the lamp is in an increasing process and is unstable, there is no problem even if there is a slight flicker of polarity reversal or a fluctuation of the arc. Further, as a matter of course, since the lamp is in the starting process, the lamp power or current does not reach the rated value. Therefore, it is not necessary to satisfy the conditions (2) to (4) in the refresh lighting mode according to the present invention. However, (5) it is required that the mode duration is appropriate.

  There are several methods for dissolving the protrusions for the condition (1), and according to the methods, there are several variations of the refresh lighting mode. Examples of the method include a method using switching of the lighting frequency, a method of setting a lamp current value at start, a method of setting a lamp power value at start, or a combination thereof.

  First, a method for performing the refresh lighting mode by frequency switching will be described. As shown in FIG. 5, since the protrusion tends to dissolve in a region where the lighting frequency is lower than fb, the frequency fr in the refresh lighting mode needs to be less than fb, and it is necessary to satisfy fr <fb. However, since the value of the frequency fb varies as described above, in setting the actual frequency fr, fb should be regarded as a wide frequency band and a frequency sufficiently separated from fb should be used. Is desirable. In order to maximize the effect of dissolving the protrusions and make the refresh lighting mode duration as short as possible, it is desirable to set fr to the lowest possible frequency. The lower limit value of fr is determined solely by circuit design constraints, and depending on the circuit design, a low frequency of 10 Hz or less is possible, but from the viewpoint of matching with the lamp (that is, one If the anode time of the electrode is too long, the electrode may be damaged), and preferably 10 Hz or more. Further, from the viewpoint of circuit design (that is, the performance of the driver IC used for the full bridge control circuit 45) Is more preferably 20 Hz or more.

  Next, a method for performing the refresh lighting mode by switching the current value at the time of starting the lamp will be described. In general, as the current flowing to the lamp at the time of starting the lamp is larger, the tendency of the protrusions to be melted by the thermal energy becomes stronger. In this method, the lamp current characteristic in the refresh lighting mode may be set to the rated current value or more. High-pressure discharge lamps have a rated lamp voltage range with a certain width. Generally, the lamp voltage is controlled at a constant lamp power within the rated lamp voltage range, and the lighting device does not exceed the lower limit of the rated lamp voltage range. Constant current control is performed to a current value at a lower limit value of the rated lamp voltage range. Therefore, in the lamp voltage range below the lower limit value of the rated lamp voltage, the refresh lighting mode can be realized if the lamp current in the refresh lighting mode is set to a value larger than the current value at the lower limit value of the rated lamp voltage range. Can do.

  Next, a method for performing the refresh lighting mode by switching the power value at the time of starting the lamp will be described. In this method, the lamp power characteristic in the refresh lighting mode may be set to be equal to or higher than the rated power value for the same reason as the method by switching the current value at the time of starting the lamp. As described above, the high-pressure discharge lamp has a rated lamp voltage range with a certain width. Generally, when the lamp voltage is below the lower limit value of the rated lamp voltage range, the lighting device has a current value at the lower limit value of the rated lamp voltage range. In the rated lamp voltage range, constant power control is performed to the rated lamp power. Therefore, if the lamp power in the refresh lighting mode is set to a value larger than the rated lamp power, the refresh lighting mode can be realized.

  In the case of the method that is performed by switching the power value at the time of starting the lamp, the power value input to the lamp is larger than the rated lamp power value when the transition to the normal lighting mode is made after a predetermined period of time. Will decrease to a value. For this reason, control may be performed so that the power value gradually decreases so that the user does not visually recognize a change in screen brightness. The same applies to the method by switching the current value.

  As a merit of the method of switching the current value or power value at the time of starting the lamp as described above, it is not necessary to switch the lighting frequency between the normal lighting mode and the refresh lighting mode, and the lighting can be performed at a single frequency, so full bridge control is possible. The circuit configuration of the circuit 45 can be relatively simplified. For example, this is particularly effective when the lighting frequency band suitable for use is narrow, such as when the boundary frequency fb is low. In other words, the refresh lighting mode can be determined without paying much attention to the value of the boundary frequency fb.

  Note that at least two of the frequency switching method, the current switching method, and the power switching method may be combined. Thereby, the protrusion dissolution effect in the refresh lighting mode can be enhanced.

  As can be seen from the above description, when this device is used for a projector, the refresh lighting mode is implemented at the time of starting the lamp, so the brightness of the projector output is not sufficient and viewing is not actively performed. Applied. Therefore, it does not hinder the user's vision.

<Determining the predetermined period>
The predetermined period is determined in advance by an experiment with an applicable lamp according to the method or combination of methods of the refresh lighting mode and the lighting parameters in the method. These methods, each parameter, and the state of the electrode protrusions in a predetermined period are observed, and the predetermined period is determined so that the electrode tip protrusions are in the state as shown in FIG. Specifically, it is desirable to determine the lighting frequency, lamp current, and lamp power during the refresh lighting mode so that the rise time of the lamp mounted on the projector is taken into consideration and set to about 3 minutes or less.

  Further, the predetermined period may be ended when the lamp voltage exceeds a certain threshold voltage. Normally, the lamp voltage immediately after the start of lighting is several tens of volts, and if it is a normal lamp, it reaches about 65V to 100V when reaching stable lighting. Therefore, for example, a threshold value may be set to about 60 V, and the predetermined period may be terminated when the lamp voltage exceeds the threshold value.

Further, as a method for determining whether or not stable lighting has been reached, the central control unit 35 calculates a differential value with respect to time of the lamp voltage, and determines that stable lighting has been reached if the differential value falls within a predetermined value. You may make it complete | finish a predetermined period.
In addition, a signal indicating that the above set time (for example, 3 minutes) has elapsed, a signal indicating that the lamp voltage has exceeded a threshold value (for example, 60 V), and the differential value of the lamp voltage are within a predetermined range. The end of the predetermined period may be determined by taking a logical sum or logical product with a signal indicating.

<Summary>
As described above, the “lighting mode” and “determining the predetermined period” have been described. However, since the dissolution control of the lamp electrode tip protrusion according to the present invention is limited only at the time of starting the lamp, the parameter relating to the lamp characteristics during the normal lighting of the lamp Therefore, no complicated control is performed to dissolve the electrode tip protrusion. In addition, the user can control the dissolution of the electrode tip protrusion without visually recognizing the brightness change or flicker of the projector.

  Furthermore, since it is possible to employ the lamp lighting frequency and waveform that emphasize the lamp life in the normal lighting mode that occupies most of the lighting time, it is easy to ensure the lamp life. The circuit configuration can be simplified using general-purpose parts.

<Design Example 1>
In consideration of the above, the inventors designed the following high pressure discharge lamp lighting device as the most preferred embodiment of the present invention. The rated power of the lamp used is 170W.
The lamp current in the normal lighting mode was a rectangular wave, and the lighting frequency fn was 150 Hz. The boundary frequency fb is around 75 Hz. A frequency switching method was adopted for the refresh lighting mode, the lamp current waveform was a rectangular wave, the lighting frequency fr was 30 Hz, and the predetermined period, which is the duration of the refresh lighting mode, was 3 minutes.

<Design example 2>
In the same lamp as in Design Example 1, the lamp current in the normal lighting mode was a rectangular wave, and the lighting frequency fn was 150 Hz. The refresh lighting mode employs a method that combines the current switching method and the power switching method. The refresh lighting mode has a lamp current value of 3.5 A and a lamp power value of 180 W. The refresh lighting mode continues for a predetermined period. Was 2 minutes.
That is, in the process of increasing the lamp voltage after the start of lighting, as shown by the solid line in FIG. 8, the lamp current becomes 3.5 A until the lamp voltage exceeds the lower limit value V ₀ of the lamp rated voltage range. The lamp power is controlled to be 180 W after the lower limit V ₀ is exceeded. And after lighting time exceeds 2 minutes, it transfers to normal lighting mode.
Incidentally, as shown by the broken line in FIG. 8, in the conventional lighting method in which the refresh lighting mode is not performed, the lamp current is controlled to be 3.3 A until the lamp voltage exceeds the lower limit value V ₀ , and the lower limit value is set. It is a premise that the lamp power is controlled to be 170 W after exceeding V ₀ . It should be noted that the lower limit value _{V 0} and 51V.
In addition, the above shows a typical preferred design example in order to clarify the outline of the design, and the present invention is not limited to the above numerical values.

<Application>
In the above embodiment, the high pressure discharge lamp lighting device that prevents flickering and improves the lamp life is shown. FIG. 9 shows a light source device as an application using the high pressure discharge lamp lighting device.
In FIG. 9, 71 is the high pressure discharge lamp lighting device of FIG. 1 described above, 72 is a reflector to which the lamp 60 is attached, and 73 is a housing incorporating the high pressure discharge lamp lighting device 71, the lamp 60 and the reflector 72. In addition, the figure is a schematic illustration of the embodiment, and the dimensions, arrangement, and the like are not as illustrated. Then, a projector is configured by appropriately arranging a video system member or the like (not shown) in the housing 73.

  As described above, the built-in high-pressure discharge lamp lighting device that prevents flickering and improves the lamp life allows the user to view the video comfortably, and can increase the cycle until the lamp is replaced. It is possible to obtain a projector that can be comfortably viewed again.

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) The “rectangular wave” as the low-frequency current in this embodiment includes a waveform that is not strictly a perfect rectangular wave (that is, a substantially rectangular wave). For example, a waveform in which a sine wave of one cycle or more is superimposed on a complete rectangular wave for the purpose other than flicker suppression, a current value at the start and end of a rectangular wave half cycle as shown in FIG. It is also assumed that the waveform includes a slightly different waveform and a waveform having a slight unevenness in the middle of the half cycle. Therefore, the lamp current in the normal lighting mode is intended to include such a waveform.
(2) In the embodiment, the AC power supply circuit is composed of a rectifier circuit, a step-down chopper circuit, and a full bridge circuit, but other configurations may be used as long as an AC rectangular wave can be supplied to the lamp. For example, if the input power source is a DC power source, the front stage of the full bridge circuit may be only a DC / DC converter. In addition, other types of circuits such as push-pull inverters may be used instead of the full bridge circuit as long as direct current can be converted into alternating current.
(3) Further, if the control circuit 30 can perform the inversion control of the transistors 41 to 44 of the full bridge circuit 40 and the PWM control of the transistor 21 of the step-down chopper circuit 20 (as a result, each waveform described above is output. If possible, the configuration within the control circuit is not limited to that shown.

  The present invention is mainly used in light source devices such as projectors, projection TVs, and projectors.

It is a figure which shows the high pressure discharge lamp lighting device of this invention. It is a flowchart which shows the lighting method of this invention. It is a figure explaining the state of the electrode of a lamp. It is a figure explaining operation | movement of this invention. It is a figure explaining the lighting frequency of each mode in the present invention. It is a figure explaining this invention. It is a figure explaining this invention. It is a figure explaining this invention. It is a figure which shows the light source device of this invention. It is a figure explaining a prior art. It is a figure explaining a prior art.

Explanation of symbols

1: AC power supply 10: Full wave rectifier circuit 11: Diode 12: Capacitor 20: Step-down chopper circuit 21: Transistor 22: Diode 23: Choke coil 24: Capacitor 30: Control circuits 31, 32, 33: Resistor 34: PWM control circuit 35: central control unit 40: full bridge circuits 41, 42, 43, 44: transistor 45: bridge control circuit 50: igniter circuit 51: igniter control circuit 60: high pressure discharge lamp 71. High pressure discharge lamp lighting device 72. Reflector 73. Enclosure

Claims (10)

A method for lighting a high-pressure discharge lamp in a high-pressure discharge lamp lighting device comprising power supply means for supplying an alternating current to a high-pressure discharge lamp, and control means for controlling the operation of the power supply means,
In the control means, applying a refresh lighting mode, which is a lighting mode for dissolving projections grown more than necessary on the electrode tip of the high-pressure discharge lamp or projections deposited other than the projections in a predetermined period after the lamp is lit. And a lighting method comprising a step of applying a normal lighting mode, which is a lighting mode in which protrusions are easily grown or maintained at the electrode tip of the high-pressure discharge lamp after the predetermined time has elapsed.   The lighting method according to claim 1, wherein the frequency of the alternating current is 10 Hz or more and 1 kHz or less, and the lighting frequency fr in the refresh lighting mode is lower than the lighting frequency fn in the normal lighting mode.   3. The lighting method according to claim 2, wherein the lighting frequency fr in the refresh lighting mode is fr <75 Hz.   2. The lighting method according to claim 1, wherein the current value in the refresh lighting mode is less than the lower limit value of the rated lamp voltage range, and the current value at the lower limit value of the rated lamp voltage range of the high-pressure discharge lamp. The lighting method is also a large value.   The lighting method according to claim 1, wherein a power value in the refresh lighting mode is a value larger than a rated lamp power of the high-pressure discharge lamp.   6. The lighting method according to claim 1, wherein the current waveform in the refresh mode is a substantially rectangular wave, and the current waveform in the normal lighting mode is a waveform in which a protrusion is easily grown or maintained at the tip of the electrode. There is a lighting method. A high-pressure discharge lamp lighting device comprising power supply means for supplying an alternating current of 10 Hz to 1 kHz to a high-pressure discharge lamp, and control means for controlling the operation of the power supply means,
The control means operates the power supply means at the lighting frequency fn when the high pressure discharge lamp is stably lit, and the lighting is lower than the lighting frequency fn during the period after the start of discharge of the high pressure discharge lamp and before reaching the stable lighting. Configured to operate the power supply means with a frequency fr;
A high pressure discharge lamp lighting device in which fr <75 Hz ≦ fn with respect to the lighting frequencies fn and fr. A high pressure discharge lamp lighting device comprising power supply means for supplying alternating current to a high pressure discharge lamp, and control means for controlling the operation of the power supply means,
When the lamp voltage is less than the lower limit value of the rated lamp voltage range after the start of discharge of the high pressure discharge lamp and before stable lighting is reached, the lower limit value of the rated lamp voltage range of the high pressure discharge lamp A high-pressure discharge lamp lighting device in which the control means is configured such that the power supply means outputs a current value larger than the current value at. A high pressure discharge lamp lighting device comprising power supply means for supplying alternating current to a high pressure discharge lamp, and control means for controlling the operation of the power supply means,
Power that is greater than the rated lamp power of the high-pressure discharge lamp when the lamp voltage is less than the lower limit value of the rated lamp voltage range after the start of discharge of the high-pressure discharge lamp and before reaching stable lighting. A high pressure discharge lamp lighting device in which the control means is configured so that the power supply means outputs.   A high-pressure discharge lamp lighting device according to any one of claims 7 to 9, a high-pressure discharge lamp, a reflector to which the high-pressure discharge lamp is attached, and a housing containing the high-pressure discharge lamp lighting device and the reflector. projector.

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