JP2007115416A - High pressure discharge lamp lighting device and lights-out method of high pressure discharge lamp - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamp current control method at light-off of the lamp capable of improving a lamp re-starting property by relaxing adhesion of mercury deviated to one side electrode of the lamp even if the lamp and an air cooling structure at projector side are not optimized. <P>SOLUTION: The high pressure discharge lamp lighting device supplying alternating current power to the high pressure discharge lamp has a control means controlling the supply of the alternating current power and a receiving means receiving a light-off signal from outside the high pressure discharge lamp lighting device. It is constructed so that the control means makes an effective value of the current flowing from one side to the other side of the high pressure discharge lamp larger than that flowing from the other side to one side thereof. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light source device such as a projector using a high-pressure discharge lamp as a light source, and more particularly to improvement of lamp current control when the lamp is turned off.

  A light source device such as a projector that uses a high-pressure discharge lamp as a light source (hereinafter generally referred to as a projector) has a large lamp temperature rise when the lamp is lit, and the optical system device inside the projector, the control board, etc. Is used while air-cooling the lamp with a DC fan or the like. Further, even after the projector switch is turned off and the lamp is turned off, the air cooling fan continues to rotate for a certain time, and the lamp that has been turned off is cooled. This is because the lamp can be restarted by lowering the lamp temperature and lowering the pressure in the lamp bulb. However, it has been found that the air cooling after the lamp is turned off may have an adverse effect on the restart of the lamp in recent years, and the adverse effect will be described below.

  In general, in order to light a high-pressure discharge lamp, a high-voltage start pulse such as 15 kV or 20 kV is applied, and the lamp is started by causing dielectric breakdown in the lamp. However, in recent years, there has been a strong demand for miniaturization and cost reduction of light source devices, so that lamps and lighting devices have also been miniaturized, and the start pulse has been changed to a low specification. In addition, as lamps become smaller, cooling has been devised, and the internal structure of the projector that creates the flow of wind that hits the lamp has also varied depending on the model. In addition, the type of the lamp is an open front type as shown in FIG. 3, the front side as shown in FIG. 4 is sealed with a lens, There are various shapes of reflectors (mirrors), and the heat capacity of the lamp itself is different. If the combination of the air cooling structure in the projector and the type and shape of the lamp is not appropriate, a temperature gradient occurs due to a difference in the temperature drop speed during air cooling between the front end side and the rear base side of the lamp bulbs 31 and 41.

  In addition, the high-pressure discharge lamp mentioned here contains mercury or an additive mainly composed of mercury. This mercury evaporates while the lamp is on, but the lamp is extinguished and liquefies as the bulb temperature decreases. When a temperature gradient is generated on the front end side 35, 45 and the rear cap side 36, 46 of the lamp bulb, mercury has a property of being biased to the electrode whose temperature has been lowered quickly.

  For example, in the case of a structure in which a large amount of cooling air hits the entire lamp or the front side of the lamp in the open front type lamp as shown in FIG. Since the temperature of the electrode also decreases earlier on the tip side, mercury is unevenly attached to the electrode 33 on the lamp tip side. On the other hand, in the case of a front-sealed lamp as shown in FIG. 4, when a large amount of cooling air hits the rear cap 46 side, the temperature of the cap-side electrode 44 of the bulb 41 decreases quickly, resulting in mercury on the cap-side electrode 44. Will be attached unevenly.

When the uneven mercury adhesion to the one-side electrode is remarkable, the one-side electrode or the electrode core bar is wrapped in mercury. In such a state, the conventional high voltage pulse of 15 kV to 20 kV was sufficient to start the engine. However, in the low pulse of about 8 kV, which has become mainstream in recent years, the restartability of the lamp is significantly reduced. As a result, a so-called restart failure occurs in which the lamp does not light at the time of restart. This is an adverse effect on the previous lamp restart.
Further, other problems such as a short circuit between electrodes caused by the adhesion of mercury to the electrodes are described in the following Patent Document 1 and Patent Document 2, and improvement measures are disclosed respectively.
Although the method is particularly different with respect to Patent Document 1, it can be said that it has the same object as the present invention in that mercury is prevented from concentrating on the electrode when the lamp is turned off and the restartability of the lamp is improved. .

Specifically, in Patent Document 1, the lamp power is restricted within a range in which discharge of the lamp power can be maintained for a certain period before the lamp is turned off (for example, a lamp with a rated power of 270 W is turned on at 50 W), and mercury concentrates on the electrode and adheres. It is disclosed that it is prevented. Patent Document 2 discloses that the lamp is restarted after the lamp is extinguished to eliminate a problem caused by mercury adhering to the electrode.
JP 2002-289379 A JP 2003-17280 A

  There are a number of parameters regarding the air cooling conditions of the lamp. On the projector side, the flow of cooling air, strength, air cooling location, air cooling time, etc., and on the lamp side, the type of lamp (front open type or sealed type), shape, size, heat capacity of the base, etc. . It is very difficult to design with these parameters taken into consideration, to derive perfect air cooling conditions, to prevent uneven mercury adhesion to the electrodes, and to achieve a state in which mercury adheres almost uniformly within the bulb. is there.

  That is, when the air cooling structure of the projector is not optimized, mercury is unevenly attached to the electrode on one side of the lamp due to the air cooling after the lamp is turned off, which becomes a factor that hinders the restart of the lamp. An object of the present invention is to reduce lamp turn-off, which can improve the restartability of the lamp by alleviating the uneven deposition of mercury on the one-side electrode of the lamp, even if the air cooling structure on the lamp and projector side is not optimized. It is to provide a method for controlling the lamp current at the time.

A first aspect of the present invention is a high-pressure discharge lamp lighting device that supplies an alternating current to a high-pressure discharge lamp, and includes a control unit that controls the supply of alternating-current power, and a turn-off signal from the outside of the high-pressure discharge lamp lighting device. Receiving means for receiving, and for a predetermined period after the receiving means receives the extinguishing signal, the control means determines the effective value of the current flowing from one electrode of the high-pressure discharge lamp to the other electrode from the other electrode. It was set as the structure made larger than the effective value of the electric current which flows toward one electrode.
As one method, the alternating current supplied to the high-pressure discharge lamp is converted into a rectangular wave current that is inverted at a predetermined cycle, and the control means is connected to one of the high-pressure discharge lamps for a predetermined period after the receiving means receives the extinction signal. The period in which current flows from one electrode to the other electrode is made longer than the period in which current flows from the other electrode to one electrode, so that one electrode of the high-pressure discharge lamp is directed to the other electrode. The effective value of the flowing current may be made larger than the effective value of the current flowing from the other electrode toward the one electrode.
Further, as another configuration, the alternating current supplied to the high pressure discharge lamp is converted into a rectangular wave current that is inverted at a predetermined cycle, and the control means is operated for a predetermined period after the receiving means receives the extinguishing signal. The amplitude of the current flowing from one electrode to the other electrode is made larger than the amplitude of the current flowing from the other electrode to the one electrode, so that one electrode of the high-pressure discharge lamp is transferred from the other electrode to the other electrode. You may make it make the effective value of the electric current which flows toward larger than the effective value of the electric current which flows toward the one electrode from the other electrode.
Further, the high pressure discharge lamp is cooled after being extinguished, and the one having the larger cooling effect by cooling is designated as the one of the electrodes.

  According to a second aspect of the present invention, there is provided a light source device comprising the high pressure discharge lamp lighting device, the high pressure discharge lamp, the reflector, the cooling means for the high pressure discharge lamp, and a housing incorporating at least the high pressure discharge lamp lighting device according to the first aspect. It is.

  A third aspect of the present invention is a method for turning off a high pressure discharge lamp lighting device that supplies an alternating current to the high pressure discharge lamp. The step of receiving in the discharge lamp lighting device, the alternating current supplied to the high pressure discharge lamp for a predetermined period after receiving the extinguishing signal, the effective value of the current flowing from one electrode to the other electrode Is a method of extinguishing, comprising the steps of increasing the effective value of the current flowing from the high pressure discharge lamp lighting device to one of the electrodes and stopping the supply of power from the high pressure discharge lamp lighting device to the high pressure discharge lamp after a lapse of a predetermined period. .

  According to the present invention, in the light source device such as a projector, the combination of the air cooling structure in the light source device such as the projector and the type / shape of the lamp is not optimized by improving the lamp current control method before the lamp is turned off. However, it is possible to alleviate the phenomenon in which mercury is unevenly attached to one side electrode of the lamp, and the restartability of the lamp can be improved as compared with the conventional lamp extinction.

  In order to achieve the above object, in the present invention, when the lamp is turned off in the projector, the value of the current flowing in the one-side polarity direction of the lamp for a certain time t is larger than the value (effective value) of the current flowing in the reverse polarity direction. After the current control is performed, the lamp is turned off. This operation will be described below.

  While the lamp is on, the electrode of the lamp repeatedly becomes an anode or a cathode depending on the polarity of the lamp current. At this time, electrons collide with the electrode serving as the anode due to the lamp current, and the collision of the electrons raises the temperature of the electrode. At this time, in an alternating lamp current, the currents in both polar directions have the same value during normal lighting, so that both lamp electrodes have the same temperature.

  Here, when the value of the current flowing in the polarity direction on one side is made larger than the value of the current flowing in the reverse polarity direction, when the electrode on one side is the anode, the electrons colliding with the anode This means that the number of electrons that collide with this anode when the other electrode becomes the anode is larger, and as a result, the temperature of the electrode serving as the anode with the larger number of electrons colliding is higher. Become high.

  In general, in the process of the temperature of the lamp decreasing after the lamp is turned off, the temperature of the electrode on one side is decreased earlier depending on the structure of the lamp and the air cooling condition of the projector. Mercury that has evaporated in the bulb begins to liquefy as the temperature of the bulb decreases, but at this time, it adheres to the electrode on which the temperature has fallen earlier. In order to prevent this, when the lamp is turned off as described above, the value of the current flowing in the one-side polarity direction for a certain time t is set to be larger than the value of the current flowing in the reverse polarity direction. The polarity of the electrode whose temperature is rapidly lowered is the anode with the higher number of electrons colliding.

In this way, immediately after the lamp is extinguished, the temperature of the electrode that rapidly decreases in temperature is higher than that of the other electrode. The temperature of the electrodes is almost the same. By satisfying the condition that this time and the time when mercury evaporated in the bulb begins to liquefy due to the temperature drop of the bulb, it is possible to prevent the phenomenon that mercury is unevenly attached to the electrode on one side, As a result, the restartability of the lamp can be improved.
Here, the conditions are the magnitude of the difference between the value of the lamp current flowing in the polarity direction on one side and the value of the lamp current flowing in the reverse polarity direction, and the time t for performing the current control just before turning off. It is.

Example 1.
Next, examples will be described with reference to the drawings.
FIG. 2 is a schematic view of a lamp housing portion in the projector. In FIG. 2, reference numeral 22 denotes an ultrahigh pressure mercury lamp often used as a light source of a projector, and is housed in a lamp box 25. In this embodiment, the lamp 22 is of the front sealing type, and the lamp itself blocks ventilation on the front side of the lamp. Reference numeral 21 denotes an air-cooling fan that cools air by flowing air in a direction of sucking air from the lamp side to the outside of the projector. In this projector, the lamp is lit by a lamp current having a value of 2.5 A and a frequency of 100 Hz.

  Here, when the lamp is extinguished, if the flow of wind is better on the rear side than the front side of the lamp box 25 due to the structure of the projector, it is closer to the base side 46 than the front end side of the lamp corresponding to 45 in FIG. Is more cooled. Further, the temperature of the electrode 44 on the base side is lower than that of the electrode 43 on the tip side, and as a result, mercury is biased and attached to the electrode 44 on the lamp base side.

  In order to solve this problem, in the present invention, the current value flowing in the direction from the electrode 44 to the electrode 43 is made larger than the current value flowing in the direction from the electrode 43 to the electrode 44 for a certain time t immediately before the lamp is turned off. The lamp is turned off after the current is controlled. Here, as shown in FIG. 5, the fixed time t is set to 10 seconds. Further, the amplitude of the current flowing from the electrode 44 to the electrode 43 is set to 2.5 A, the time width is set to 6 msec, the amplitude of the current flowing from the electrode 43 having the reverse polarity to the electrode 44 is set to 2.5 A, and the time is set. The width was 4 msec.

  In this way, the lamp current is controlled so that the temperature of the electrode 44 is higher than the temperature of the electrode 43 immediately after the lamp is turned off. It can be substantially the same. The mercury vaporized in the lamp bulb begins to liquefy as the temperature of the bulb decreases, and the time at which both electrode temperatures become substantially the same is approached, thereby causing uneven mercury adhesion to the base electrode 44. Can be relaxed.

  Here, in order to confirm the effect of the present invention with respect to the restart failure due to the uneven adhesion of mercury to the one-side electrode described above, the restart failure is forcibly generated by the lamp turn-off method of this embodiment and the conventional lamp turn-off. The results of carrying out the experiment are shown below.

  In this experiment, a lighting device in which the specification of the lamp starting pulse is changed to a low pulse of 4 kV in order to forcibly cause a restart failure, and the lamp cooling mechanism inside the projector is further cooled on the lamp base side. It was. The ambient temperature was normally 25 ° C., and the lamp was turned on for 30 minutes and then the lamp was turned off for 60 minutes. When the projector was restarted, it was confirmed that a lamp restart failure did not occur. The reason why the lamp is turned on / off in this time distribution is that the lamp temperature rise after lighting can be sufficiently stabilized, and the lamp temperature after the lamp is turned off is reduced to such an extent that the result of this experiment hardly affects the lamp temperature. Because it can.

In addition, the projector should not be moved or shocked or vibrated while it is left unlit for 60 minutes. This is because mercury adhering to the electrode of the lamp falls into the bulb or the position of the mercury changes, thereby affecting the restartability.
The lamp used in the experiment was the front-sealed type represented in FIG. 4 described above, and five lamps were tested three times by each air cooling method, and a total of 15 experiments were performed.

  As a result of the experiment, 5 out of 15 restart failures occurred when the conventional lamp was turned off. In contrast, in the embodiment of the lamp extinguishing method of the present invention, the occurrence of the restart failure was 0 times out of 15. From this result, it has been confirmed that the present invention has a sufficient effect on lamp restart failure due to mercury adhesion to the electrode.

  As another embodiment, the current value flowing in the direction from the electrode 44 to the electrode 43 for a certain time t immediately before the lamp is turned off is made larger than the current value flowing in the direction from the electrode 43 to the electrode 44. Thus, the time width of the current flowing in the direction from the electrode 44 to the electrode 43 remains 3.0 m, and the amplitude is 3.0 A, and the time width of the current flowing in the direction from the electrode 43 having the opposite polarity to the electrode 44 remains 5 msec. 0.0A. The fixed time t was also set to 10 seconds as in the first embodiment, and a similar experiment was performed. However, similar to the first embodiment, a good result was obtained compared to the conventional lamp extinguishing.

  Further, even if the predetermined time t is shorter than that in the above embodiment, the difference between the current value flowing in the direction from the electrode 44 to the electrode 43 and the current value flowing in the direction from the electrode 43 to the electrode 44 is increased. As well as good results were obtained.

  FIG. 7 is a block diagram showing an example of a circuit configuration of a specific high-pressure discharge lamp lighting device. As shown in FIG. 7, the lighting device includes a step-down chopper circuit 51, a full bridge circuit 52 that converts the output from the step-down chopper circuit 51 into a rectangular wave current and applies it to the lamp 54, and an igniter circuit that generates a pulse for starting the lamp. 53, a control circuit 55 for controlling the step-down chopper circuit 51 and the full bridge circuit 52, and a receiving circuit 56 for receiving a turn-off signal from the outside of the lighting device. Note that a resonance circuit including an inductor connected in series to the lamp 54 and a capacitor connected in parallel to the lamp 54 is provided in the igniter circuit 53 as necessary.

  The control circuit 55 has a lamp current waveform as shown in FIG. 1 before the receiving circuit 56 receives the extinction signal, and a lamp current waveform as shown in FIG. 5 or FIG. 6 after the extinction signal is received. The step-down chopper circuit 51 and the full bridge circuit 52 are controlled. Specifically, in order to generate the current waveform shown in FIG. 5, the output of the step-down chopper circuit 51 may be kept constant and the output polarity of the full bridge circuit may be inverted every 6 msec and 4 msec. In order to generate the current waveform shown in FIG. 6, the output polarity inversion timing of the full bridge circuit may be kept equal, and the output of the step-down chopper circuit 51 may be increased or decreased at each inversion timing. Of course, it is possible to change both the period and the amplitude of the positive current and the negative current by combining the control of FIG. 5 and FIG.

  In the embodiment, a rectangular wave current with a full bridge circuit is used as the most preferable example, but other waveforms (sine wave, triangular wave, other combined wave) and others are within the range satisfying the lamp specifications. A lighting method with a frequency of may be used. Accordingly, other circuit methods (push-pull type, half-bridge type, etc.) can be adopted as long as the circuit can generate such a current waveform. Furthermore, in the present embodiment, a combination of 6 msec and 4 msec is used as a preferable example, but other combinations of period widths may be used, and the waveform may not be a constant cycle. In other words, it is sufficient that the difference between the effective values of the positive current and the negative current supplied to the lamp can be controlled appropriately regardless of which lighting method or circuit method is used. Further, the step-down chopper circuit may be another DC output circuit such as a step-up / step-down chopper as long as the DC voltage or current can be controlled appropriately.

  In addition, regarding the setting of each condition described above, the period t is determined by the specifications of the projector and the size of the difference between the value of the lamp current flowing in the polarity direction on one side or the value of the lamp current flowing in the reverse polarity direction is limited. Must be selected within a range that does not damage the electrode of the lamp.

Example 2
In the first embodiment, a high pressure discharge lamp lighting device capable of starting a reliable discharge is shown. In this embodiment, a light source device (projector) using the high pressure discharge lamp lighting device is shown.
FIG. 8 is a diagram showing a projector according to the second embodiment. In the figure, 60 is the high-pressure discharge lamp lighting device described above, 62 is a reflector to which the lamp bulb 61 is attached, and 63 is a housing that incorporates or supports the high-pressure discharge lamp lighting device 60, the lamp bulb 61, and the reflector 62. . In addition, the figure is a schematic illustration of the embodiment, and the dimensions, arrangement, and the like are not as illustrated. Further, a video system member or the like (not shown) is appropriately arranged in the housing 63.
Thereby, since the high-pressure discharge lamp lighting device capable of starting reliably is built in, a highly reliable projector can be obtained.

  The extinguishing signal is generated, for example, when the user presses the off switch for extinguishing. However, even if the user presses the off switch, time t (for example, 10 seconds) is required until the lamp is actually extinguished. . For this reason, it is assumed that a user who has a preconception that when the off switch is pressed, the light is turned off instantly has doubts about his own action and presses the off switch many times. Therefore, in order to ensure the reliability around the off switch and the user's sense of security, it may be displayed during the period t that the projector is preparing to be turned off. As the display method, for example, an LED lamp or the like attached to the main body may be turned on or blinked, the message may be displayed on a screen that is a projection target, or notification may be made by voice or the like. It may be.

  Furthermore, in the projector having the above-described configuration, the connection (two lines) between the lighting device and the lamp is determined on a one-to-one basis, so that the connection is not performed in any other correspondence at the time of assembly. The lamp current must be increased in any direction. Specifically, the wiring A from the base of the lamp electrode can be wired only in a predetermined combination such as the output terminal a of the lighting device and the wiring B from the tip side of the output terminal b. Is desirable. As one of the countermeasures, the shape of each wiring and / or each terminal may be a shape that can be connected only by the above combination. Further, the length of the wiring and the position of the output terminal may be devised so that the wiring A does not reach the output terminal b and / or the wiring B does not reach the output terminal a. Of course, the wirings may be visually identified by changing the color of the covering between the wirings A and B or marking some notation.

  As described above, according to the present invention, in the light source device such as a projector, the combination of the air cooling structure in the light source device such as the projector and the type and shape of the lamp is improved by improving the lamp current control method before the lamp is turned off. Even if it is not optimized, it is possible to alleviate the phenomenon that mercury is unevenly attached to one side electrode of the lamp, and the restartability of the lamp can be improved compared with the conventional lamp extinction.

  The utilization of the present invention is mainly used for light source devices such as projectors, projection TVs, and projectors.

The figure which shows the lamp current waveform at the time of steady lighting The schematic diagram of the lamp compartment in the projector Front view of high-pressure discharge lamp (front view of reflector only) External view of front-sealed high-pressure discharge lamp (cross-sectional view of reflector only) The figure which shows an example of the lamp current waveform of this invention Example The figure which shows the other example of the lamp current waveform of this invention Example The figure which shows the circuit structural example of this invention Example The figure which shows the projector of an Example of this invention

Explanation of symbols

21 ... Air-cooling fan 22 ... Lamp 23 ... Lamp base 24, 48 ... Front lens 25 ... Lamp box 26 ... Lamp cable 27 ... Ventilation openings 31, 41, 61 ... Lamp bulbs 32, 42, 62 ... Reflectors (mirrors)
33, 43 ... Lamp tip side electrodes 34, 44 ... Lamp cap side electrodes 35, 45 ... Lamp tip side sealing portions 36, 46 ... Lamp cap 47 ... Lamp lead wire 48 ... Front lens 51 ... Step-down chopper circuit 52 ... Full bridge Circuit 53 ... Igniter circuit 54 ... Lamp 55 ... Control circuit 56 ... Reception circuit 60 ... High-pressure discharge lamp lighting device 63 ... Housing

Claims (6)

A high pressure discharge lamp lighting device for supplying an alternating current to a high pressure discharge lamp,
Control means for controlling supply of the alternating current, and receiving means for receiving a turn-off signal from the outside of the high-pressure discharge lamp lighting device,
For a predetermined period after the receiving unit receives the extinguishing signal, the control unit calculates the effective value of the current flowing from one electrode of the high-pressure discharge lamp to the other electrode from the other electrode. A high pressure discharge lamp lighting device characterized in that it is larger than the effective value of the current flowing toward the electrode. The high pressure discharge lamp lighting device according to claim 1,
The alternating current supplied to the high-pressure discharge lamp is a rectangular wave current that is inverted at a predetermined cycle,
For a predetermined period after the receiving means receives the extinguishing signal, the control means has a period during which current flows from one electrode of the high-pressure discharge lamp to the other electrode. By making it longer than the period in which current flows toward the electrode, the effective value of the current flowing from one electrode of the high-pressure discharge lamp to the other electrode flows from the other electrode toward the one electrode. A high pressure discharge lamp lighting device characterized in that it is larger than the effective value of the current. The high pressure discharge lamp lighting device according to claim 1,
The alternating current supplied to the high-pressure discharge lamp is a rectangular wave current that is inverted at a predetermined cycle,
During a predetermined period after the receiving means receives the extinguishing signal, the control means determines the amplitude of the current flowing from one electrode of the high-pressure discharge lamp to the other electrode from the other electrode to the one of the other electrodes. By making it larger than the amplitude of the current flowing toward the electrode, the effective value of the current flowing from one electrode of the high-pressure discharge lamp toward the other electrode flows from the other electrode toward the one electrode. A high pressure discharge lamp lighting device characterized in that it is larger than the effective value of the current.   The high-pressure discharge lamp lighting device according to any one of claims 1 to 3, wherein when the high-pressure discharge lamp is cooled after being extinguished, the one having the larger cooling effect by the cooling is A high pressure discharge lamp lighting device characterized by being designated as an electrode.   5. A light source comprising the high pressure discharge lamp lighting device according to any one of claims 1 to 4, a high pressure discharge lamp, a reflector, a cooling means for the high pressure discharge lamp, and a housing containing at least the high pressure discharge lamp lighting device. apparatus. A turn-off method in a high-pressure discharge lamp lighting device for supplying an alternating current to a high-pressure discharge lamp,
Receiving a turn-off signal from the outside of the high-pressure discharge lamp lighting device at the high-pressure discharge lamp lighting device during lighting of the high-pressure discharge lamp;
For a predetermined period after receiving the turn-off signal, the effective value of the current flowing from one electrode to the other electrode and the effective current flowing from the other electrode to the one electrode are determined for the alternating current. And a step of stopping the supply of electric power from the high-pressure discharge lamp lighting device to the high-pressure discharge lamp after elapse of the predetermined period.

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