JP2009086516A - Air cooling method of high-voltage discharge lamp, and light source device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce flicker by discharge origin movement by dissolving unnecessary sub-projections grown on an electrode of a high-voltage discharge lamp. <P>SOLUTION: The light source device comprises a high-discharge lamp including a light emitting tube having a pair of electrodes oppositely arranged in the inside and at least halogen, mercury and rare gas encapsulated therein; a lighting device for lighting the high-voltage discharge lamp; an air cooling fan for cooling the high-voltage discharge lamp; and a control means for controlling operation of the air cooling fan based on the operation of the lighting device. The rotating speed of the air cooling fan is set to f0 until a predetermined period passes from the lighting start of the high-voltage discharge lamp, and set to f1 higher than f0 after the lapse of the predetermined period. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a light source device such as a projector, a projection TV, or a projector using a high pressure discharge lamp as a light source, and more particularly to improvement of air cooling control for a high pressure discharge lamp.

  In a light source device such as a liquid crystal projector, a high pressure discharge lamp such as a high pressure mercury lamp as shown in FIG. 7 (hereinafter referred to as “lamp” or “high pressure discharge lamp”) is used. Such a lamp is filled with a halogen substance, a rare gas, and mercury, and a pair of electrodes are arranged opposite to each other in the arc tube. Such a lamp is usually lit by a rectangular wave current having a fixed frequency of 50 Hz to 400 Hz.

  As shown in FIG. 7, the lamp is provided with an arc tube 1 made of quartz glass or the like, and a light emitting portion (expanded portion) 2 having a sealed space is provided near the center of the arc tube. Mercury, argon as a starting auxiliary gas, and bromine as a trace amount of halogen for preventing blackening are enclosed in the sealed space of the light emitting unit 2, and a pair of electrodes 3 a and 3 b made of tungsten are opposed to each other. Yes. Each electrode 3a, 3b is connected to a lead rod via molybdenum foils 5a, 5b embedded in sealing portions 4a, 4b for hermetically sealing both ends of the light-emitting portion 2, and further a power supply lead wire (see FIG. (Not shown), lamp power is supplied from the high pressure discharge lamp lighting device described above through the lead wire.

By the way, when the lamp is lit with an alternating current as described above, the starting point of the discharge arc is determined in the initial stage of use, and a protrusion is formed and grows at the tip of the electrode. Here, a protrusion is formed at the tip of the electrode, and the principle of growth of the protrusion is not necessarily clear, but is assumed as follows.
The heated tungsten evaporates and combines with halogen and the like present in the arc tube to form a tungsten compound. This tungsten compound is diffused from the vicinity of the tube wall to the vicinity of the electrode tip 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 protrusions (hereinafter referred to as “halogen cycle”).

  Thus, at the beginning of lighting, the electrode grows in a protruding shape as shown in FIG. This protrusion (hereinafter referred to as “main protrusion”) is a starting point of the arc and is a protrusion necessary for stabilizing the discharge. If the lamp is turned on in the absence of the main projection, the discharge start point moves and the arc is not stable, so that flickering that can be seen by human eyes occurs.

  By the way, when about 100 hours elapse, the main protrusion repeats growth and wear with the lighting time. However, after 2000 hours, the balance of the halogen cycle is lost and the main protrusion gradually wears out as shown in FIG. 8B, and another protrusion around the main protrusion as shown in FIG. 8C. (Hereinafter referred to as “sub-projections”) occurs. Only one sub-projection may be generated, or two or more sub-projections may be generated, causing flickering due to the discharge starting point moving between the sub-projections.

Patent Document 1 discloses that an electrode surface repair period is provided to repair such a problem that the electrode surface becomes rough and sub-projections are generated. 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 the problematic sub-projections.
Japanese Patent No. 3840054

  The present invention is particularly directed to a light source device such as 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.

  In Patent Document 1, since the lighting frequency during the repair period is 5 Hz or less, or a lamp current greater than the rated current is applied, control is performed according to the repair period during stable lighting (particularly during the content screening). 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, even if the countermeasure according to this document has an effect on a specific lamp, it cannot be said that it is a suitable countermeasure from the viewpoint of vision.

  According to a first aspect of the present invention, there is provided a high-pressure discharge lamp having an arc tube in which at least a halogen, mercury and a rare gas are sealed, and a lighting device for lighting the high-pressure discharge lamp. In a light source device having an air cooling fan for cooling the high pressure discharge lamp and a control means for controlling the operation of the air cooling fan based on the operation of the lighting device, the control means has passed a predetermined period from the start of lighting of the high pressure discharge lamp. Until then, the rotation speed of the air cooling fan is set to f0, and after the elapse of a predetermined period, the rotation speed of the air cooling fan is set to f1 higher than f0.

  According to a second aspect of the present invention, there is provided a projector including the light source device according to the first aspect, a reflector attached to the high pressure discharge lamp, and a casing that houses the light source device and the reflector.

  According to a third aspect of the present invention, there is provided a high-pressure discharge lamp having an arc tube in which at least a halogen, mercury and a rare gas are sealed, and a lighting device for lighting the high-pressure discharge lamp. An air cooling method for a high pressure discharge lamp in a light source device comprising an air cooling fan for cooling a high pressure discharge lamp and a control means for controlling the operation of the air cooling fan based on the operation of a lighting device, comprising: (A) a high pressure discharge lamp From the start of lighting until the elapse of a predetermined period, and (B) after the elapse of the predetermined period, the step of operating the air cooling fan at a speed f1 higher than f0. It is an electric air cooling method.

In the first and third aspects, the predetermined period includes: (i) the lamp voltage of the high pressure discharge lamp is equal to or less than a predetermined value; and (ii) the elapsed time from the start of lighting of the high pressure discharge lamp is equal to or less than the predetermined value. It was defined as a period satisfying at least one of the following.
Specifically, the predetermined value of the lamp voltage is preferably a voltage selected from 65V to 75V.
The predetermined value of the elapsed time is preferably set to a time selected from 8 minutes to 12 minutes.

  According to the present invention, the temperature of the lamp electrode rises by rotating the rotational speed of the air cooling fan at f0 which is less than f1 during normal operation for a predetermined period, and unnecessary sub-projections grown on the electrode of the lamp can be dissolved. Thus, flickering due to movement of the discharge starting point can be suppressed.

  In addition, since it is possible to take measures against secondary protrusions simply by reducing the rotation speed of the air cooling fan for a predetermined period, there is no visual discomfort due to fluctuations in the light output, and new problems such as noise caused by lamp current modulation There is no cause.

FIG. 1 shows a block diagram of a light source device 100 of the present invention. The light source device 100 controls the air cooling fan 104 based on the operation of the high pressure discharge lamp 101, the lighting device 102 for lighting the high pressure discharge lamp 101, the air cooling fan 104 for cooling the high pressure discharge lamp 101, and the lighting device 102. Control means 103 is included. It is assumed that the lighting device 102, the control means 103, and the air cooling fan 104 are appropriately powered.
When the high-pressure discharge lamp 101 is turned on by the lighting device 102 through a starting operation, a signal indicating the start of lighting is sent from the lighting device 102 to the control means 103. As will be described later, the control means 103 changes the rotational speed of the air cooling fan 104 at the time when a predetermined period t1 has elapsed since the start of lighting.

  FIG. 2 shows the relationship between the elapsed time from the start of lighting and the rotational speed of the air cooling fan 104. Normally, the rotation speed f1 is applied during lighting, but a rotation speed f0 lower than the normal rotation speed f1 is applied until a predetermined period t1 elapses from the start of lighting. The rotation speed f0 only needs to be f0 <f1, and is a concept including f0 = 0, that is, a stopped state.

  With respect to the predetermined period t1, (i) the lamp voltage data of the high-pressure discharge lamp 101 acquired in the lighting device 102 is output to the control means 103, and the period during which the lamp voltage is equal to or less than the predetermined value is defined as the predetermined period t1. (Ii) The lighting device 102 or the control means 103 measures the elapsed time from the start of lighting, and defines the period during which the elapsed time from the lighting start is equal to or less than a predetermined value as the predetermined period t1. May be. It should be noted that the condition (i) or (ii) may be applied alone to determine the predetermined period t1, or the predetermined period may be obtained by taking the logical product or logical sum of the judgment results based on the conditions (i) and (ii). t1 may be determined.

  Specifically, the predetermined value of the lamp voltage in the condition (i) may be 65V to 75V, more preferably about 70V. In a high pressure discharge lamp, discharge with a rare gas is performed immediately after the start of lighting, and the lamp voltage during that period is as low as several tens of volts. Thereafter, when mercury or the like evaporates to reach stable lighting, the lamp voltage becomes 65V to 75V (if the new lamp has no projection or is small). Therefore, after detecting the start of lighting, it can be determined that stable lighting has been reached by detecting that the lamp voltage has reached about 70V.

  The start of lighting may be detected by detecting that the lamp voltage has changed from infinity (detection upper limit value) to several tens of volts (for example, 10 V). The detection of the lighting start may be configured such that the control unit 103 acquires and detects the lamp voltage data, or the lighting unit 102 detects the lighting start and outputs a signal indicating the lighting start to the control unit 103. It is good also as a structure.

Further, the predetermined value of the elapsed time in the condition (ii) may be 8 minutes to 12 minutes, more preferably about 10 minutes. This is due to the fact that the lamp has reached stable lighting and needs to be cooled to a normal level in the vicinity of about 10 minutes after the start of lighting.
Further, it is desirable to apply f1 instead of f0 as the rotation speed before starting the lamp lighting even after the lighting device is started. This is because in the case of performing hot restart (starting in a state where the lamp is warm), starting performance is improved by cooling the lamp by increasing the number of revolutions. Therefore, if the elapsed time is counted after starting the lighting device, it is desirable to set the rotation speed to f0 in a period of about 5 seconds or more and 10 minutes before starting.

  Supplementally, if the control means 103 can obtain information related to the lighting start with the configuration described in the condition (i), the f0 application period may be within about 10 minutes from the lighting start, and the control means 103 starts the lighting start. In the case of a configuration in which information regarding the information cannot be obtained, the f0 application period may be set to be 5 seconds or more and about 10 minutes or more after the start-up of the lighting device 102 (for example, power-on). In any case, the rotation speed f0 may be applied for about 10 minutes immediately after the start of lighting.

As a result, the temperature of the lamp electrode rises within a predetermined period t1 at the beginning of lighting, and unnecessary sub-projections grown on the electrode of the lamp can be dissolved.
In addition, since the present invention is configured to change only the number of rotations of the air cooling fan using a lighting device and an air cooling fan as used in a conventional light source device, it provides a highly versatile counter projection countermeasure. Can do.

  FIG. 5 is a diagram showing a configuration of the projector 110 as the light source device of the present invention. A reflector 111 is attached to the high-pressure discharge lamp 101, and the high-pressure discharge lamp 101, the reflector 111, the lighting device 102, the control means 103, and the air cooling fan 104 are built in the housing 112. In addition, the figure is illustrated schematically, and the dimensions and arrangement are not as illustrated. Then, a projector is configured by appropriately arranging a video system member or the like (not shown) in the housing 112.

  FIG. 4 is a schematic view of a lamp storage unit in the projector. The lamp 404 is a front-sealed type whose front surface is covered with a front glass 406, and the lamp itself blocks ventilation on the front side of the lamp. In addition, the air cooling fan 400 (air is sucked in from the ventilation opening 403) is air cooled by flowing air in the direction of sucking air from the lamp side to the outside of the projector. This figure is an example, and an open front type or an air cooling method in which an air cooling fan is applied to the lamp may be used. Reference numerals 401, 402, and 405 denote a lamp base, a lamp cable, and a lamp box, respectively.

FIG. 5 is a flowchart of the lamp air cooling method of the present invention.
When the power is turned on, a starting operation is performed in step S500, and lighting is started.
In step S501, the air cooling fan 4 is driven at the rotation speed f0.
In step S502, it is determined whether or not the predetermined period t1 has elapsed. If not, the process returns to step S501 to maintain the rotational speed f0, and if it has elapsed, the process proceeds to step S503 and the rotational speed is increased to f1.
Note that the determination of whether or not the predetermined period t1 has elapsed in step S502 may be made based on the lamp voltage or the elapsed time as described above.

  FIG. 6 shows an example of a circuit configuration of the lighting device 102. The 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. A full bridge circuit 40 for converting the DC output voltage of the current 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, the step-down chopper circuit 20 and the full bridge The control circuit 30 is configured to control the 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 37. The 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 450 W.

  In the control circuit 30, resistors 31 and 32 are lamp voltage detection circuits for detecting the lamp voltage, and resistor 33 is for detecting the lamp current. The detected lamp voltage and lamp current are multiplied by a multiplier 34 to detect lamp power. The error amplifier 35 compares the output of the multiplier 34 with the voltage of the DC power supply 38, the output of the error amplifier 35 is input to the PWM control circuit 37, and the ON width of the transistor 21 of the step-down chopper circuit 20 is controlled. Thereby, constant lamp power control is performed.

  In the central control circuit 300, a lamp voltage is detected using a microcomputer (not shown) or the like, or a predetermined time is counted. When a predetermined period elapses, the control means 103 (projector) is used using a UART (serial communication system) or the like. Sent to the microcomputer on the main unit side to adjust the rotation speed of the air cooling fan. As described above, the predetermined time may be counted by the control means 103 (microcomputer on the projector main body side).

As described above, since the lighting device with improved visibility and reliability is incorporated, the user can comfortably view the video and can obtain a highly reliable projector.
In addition, the present invention can be used not only for projectors but also for other light source devices as long as the high pressure discharge lamp is turned on while being cooled by a fan.

It is a block diagram which shows the light source device of this invention. It is a figure explaining the air cooling method of this invention. It is a figure which shows the projector of this invention. It is the schematic of the lamp | ramp storage part in a projector. It is a flowchart of the air cooling method of this invention. It is a figure which shows the high pressure discharge lamp lighting device of this invention. It is a figure explaining the structure of a lamp | ramp. It is a figure explaining the state of the electrode of a lamp.

Explanation of symbols

1: AC power supply 10: Full-wave rectifier circuit 20: Step-down chopper circuit 30: Control circuit 40: Full bridge circuit 50: Igniter circuit 60: High pressure discharge lamp 100: Light source device 101: High pressure discharge lamp 102: Lighting device 103: Control means 104: Air cooling fan 110: Projector 111: Reflector 112: Housing 300: Central control circuit 400: Air cooling fan 401: Lamp cap 402: Lamp cable 403: Opening for ventilation 404: Lamp 405: Lamp box 406: Front glass

Claims (9)

A high pressure discharge lamp having an arc tube in which at least a halogen, mercury, and a rare gas are sealed, a lighting device for lighting the high pressure discharge lamp, and a cooling device for cooling the high pressure discharge lamp. And a light source device comprising a control means for controlling the operation of the air cooling fan based on the operation of the lighting device,
The control means sets the rotational speed of the air-cooling fan to f0 until a predetermined period has elapsed from the start of lighting of the high-pressure discharge lamp, and after the predetermined period has elapsed, the rotational speed of the air-cooling fan is higher than f0. A light source device configured as described above.   2. The light source device according to claim 1, wherein the predetermined period is (i) a lamp voltage of the high-pressure discharge lamp is a predetermined value or less, and (ii) an elapsed time from the start of lighting of the high-pressure discharge lamp is a predetermined value or less. A light source device defined as a period satisfying at least one of the following.   3. The light source device according to claim 2, wherein the predetermined value of the lamp voltage in (i) is a voltage selected from 65V to 75V.   The light source device according to claim 2, wherein the predetermined value of the elapsed time in (ii) is a time selected from 8 minutes to 12 minutes.   A projector comprising the light source device according to any one of claims 1 to 5, a reflector attached to the high-pressure discharge lamp, and a housing that houses the light source device and the reflector. A high pressure discharge lamp having an arc tube in which at least a halogen, mercury, and a rare gas are sealed, a lighting device for lighting the high pressure discharge lamp, and a cooling device for cooling the high pressure discharge lamp. An air-cooling fan, and a method for air-cooling a high-pressure discharge lamp in a light source device comprising control means for controlling the operation of the air-cooling fan based on the operation of the lighting device
(A) operating the air-cooling fan at a rotation speed f0 until a predetermined period elapses from the start of lighting of the high-pressure discharge lamp; and (B) after a lapse of the predetermined period, at a rotation speed f1 higher than the f0. A high pressure discharge lamp air cooling method comprising the step of operating the air cooling fan.   The high-pressure discharge lamp air cooling method according to claim 6, wherein the predetermined period is (i) a lamp voltage of the high-pressure discharge lamp is equal to or lower than a predetermined value, and (ii) an elapsed time from the start of lighting of the high-pressure discharge lamp. A high-pressure discharge lamp air cooling method defined as a period satisfying at least one of a predetermined value and less.   The high-pressure discharge lamp air cooling method according to claim 7, wherein the predetermined value of the lamp voltage in (i) is a voltage selected from 65V to 75V.   The high-pressure discharge lamp air cooling method according to claim 7, wherein the predetermined value of the elapsed time in (ii) is a time selected from 8 minutes to 12 minutes.

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