JP2004319193A5 - - Google Patents

Description

[Document name] statement
Patent application title: Method and device for lighting a high pressure discharge lampTheVideo equipment used
[Claim of claim]
    1. In a transient state in which the lamp is turned off, the lamp power supplied to the electrode is reduced to the extent that the arc discharge does not disappear so that the lamp temperature reaches the equilibrium temperature and the lamp temperature becomes the equilibrium temperature. A method of lighting a high pressure discharge lamp comprising interrupting a current supply to the electrode.
    2. A lighting method of a high pressure discharge lamp used as a light source of a video apparatus,
  In the transition from lighting to turning off, the image is switched off and the image is not displayed, and the power supplied to the high-pressure discharge lamp is reduced to the extent that the arc discharge does not disappear, and the lamp temperature becomes the equilibrium temperature. The method for operating a high pressure discharge lamp, comprising: maintaining the lamp until the lamp temperature becomes equal to, and interrupting the current supply to the electrodes when the lamp temperature reaches the equilibrium temperature.
    3. The method of lighting a high pressure discharge lamp according to claim 1, wherein the reduction amount of the lamp power is 1/2 to 1/20 of the rated output.
    4. The method of lighting a high pressure discharge lamp according to any one of claims 1 to 3, wherein the reduction time of the reduction lamp power is 60 seconds or more.
    [Claim 5]
(a) A lighting and starting circuit for starting and lighting up by applying a high voltage pulse or low voltage DC voltage to a high pressure discharge lamp;
(b) a stable lighting circuit connected to the lighting start circuit to stably light the high pressure discharge lamp;
(c) a power control unit that controls power supply from the stable lighting circuit to the high pressure discharge lamp;
(d) The power control unit controls the stable lighting circuit so that the stable supply of lighting power from the stable lighting circuit to the high pressure discharge lamp is performed during stable lighting, and the high pressure discharge lamp Control the stable lighting circuit so that the lamp power to the high pressure discharge lamp is limited to the lamp power to the extent that the arc discharge between the electrodes does not disappear in the transition state from stable lighting to extinguishing. A lighting device for a high pressure discharge lamp, comprising: a lamp power output reduction / optical engine control circuit that outputs an image off signal to an optical engine that sends an image to a screen so as not to be in the state of.
    6. The lighting device for a high pressure discharge lamp according to claim 5, wherein the high voltage pulse is 10 kV to 15 kV.
    7. A lighting device for a high pressure discharge lamp according to claim 5, wherein the low voltage DC voltage is 1 kV to 4 kV.
    [Claim 8]
(a) The screen which projects a picture,
(b) an optical engine that projects an image on the screen;
(c) a high pressure discharge lamp for supplying light to the optical engine;
(d) starting lighting circuit for applying starting lighting voltage to the high pressure discharge lamp, and stable lighting circuit for supplying stable lighting power to the high pressure discharge lamp at the time of stable lighting;
(e) Control the optical engine together with the switch-off of the video equipment to make the screen non-image state, and when the high-pressure discharge lamp reaches the equilibrium temperature by cooling after the switch-off, or the high-pressure discharge lamp An imaging apparatus comprising: a lamp power reduction / optical engine control circuit which turns off the high pressure discharge lamp after a considerable time which has been reached.
Detailed Description of the Invention
      [0001]
    Field of the Invention
  According to the present invention, in the transition state from the switch-off to the high pressure discharge lamp reaching the equilibrium temperature, the image can be reappeared momentarily on the screen when the switch is turned on again after the high pressure discharge lamp is turned off. The present invention relates to a lighting method of a high pressure discharge lamp for video equipment capable of reappearing an image on a screen in a short time of several seconds, a lighting device therefor, and a video equipment using the lighting device.
      [0002]
    [Prior Art]
  The high-pressure discharge lamp (1 ') with a short arc length is used as a light source for business or general purpose video equipment (B') (including general home appliances) such as projectors and rear projection televisions. The problem as a light source of B ') is that the high temperature relighting time (hot re-strike time = stable light then extinguished, relamped, lamp temperature (generally around 900 ° C) is predetermined for relighting The temperature needs to be lowered to the temperature (= restartable temperature [when applying high pulse starting voltage of 15 kV as starting lighting voltage, generally 400 ° C]), high pulse starting voltage of 15 kV as starting lighting voltage Wait time from off to on again even when applying(t1)For example, it has a long point of 30 seconds [Fig. 2 (b)]. A block circuit diagram in that case is shown in FIG.
      [0003]
  In video equipment (B ') that uses a high-pressure discharge lamp (1') as a light source, in the case of continuous use, standby time(t1)The length of time (ie, the time from turn-off to turn-on) is not a problem in practical use, but it is an image device (B ') that repeatedly switches on and off in a short time, such as a rear projection television. Wait time of about 30 seconds for common home appliances(t1)Length is a big problem. That is, in the case of the present normal television, an image appears on the screen simultaneously with the switch on, and the image disappears from the screen simultaneously with the switch off. Users already have these features as a preconception against television.
      [0004]
  This is, of course, a performance that is also required for a projection television, and when a picture does not appear on the screen almost simultaneously with the switch-on, the viewer feels uncomfortable with the projection television (e.g. Performance may be a problem for the quality of the projection television.
      [0005]
  However, as long as a high pressure discharge lamp (1 ') is used as a light source, the length of the above-mentioned waiting time (t1) is not good, and even if the high starting voltage of 10 kV-15 kV can be applied, a high voltage igniter Even if (20 ') is used, the high pressure discharge lamp (1') should be turned on again at the same time as the switch-on immediately after turning off (at least after a short time of several seconds after turning off) to make the image appear on the screen Was impossible. In particular, this is not possible when the starting voltage is a low DC voltage such as 1 kV to 4 kV (this merit will be described later).
      [0006]
  Another possible problem associated with the start of the high pressure discharge lamp (1 ') is the occurrence of a mercury bridge between the electrodes after extinguishing. In particular, an excessive amount of mercury with respect to the volume is enclosed in the light emitting tube portion 12 'of the recent high pressure discharge lamp 1'. In such a high pressure discharge lamp (1 ′), mercury adheres to the electrodes in the form of dew condensation in the cooling process of the high pressure discharge lamp (1 ′) after extinguishing, and if this occurs between the electrodes, shorts the both electrodes, It is also pointed out that it is a mercury bridge that inhibits relighting.
      [0007]
  As prior patent documents to the invention according to claim 1, the invention described in Japanese Patent Application Laid-Open No. 2002-289379 by the present inventors can be mentioned.
      [0008]
      [Patent Document] Japanese Patent Application Laid-Open No. 2002-289379
      [0009]
      [Problems to be solved by the invention]
  The present invention has been made in view of the problems of the prior art. First, although the high-pressure discharge lamp is used, the discharge state is instantly restored in the transient state immediately after the switch is turned off, and Second, there is a need to develop a lighting method for a high-pressure discharge lamp especially for video equipment, which can be performed in a short time not possible conventionally, such as re-lighting by switch re-closing after extinguishing. We are in the development of a lighting circuit that can implement the method, in particular, a lighting circuit that can be relighted in a short time without applying an excessive high-pressure starting current to the high-pressure discharge lamp. A video apparatus that uses a lighting circuit, instantly restores the discharge state in a transient state immediately after extinguishing, and can perform relighting due to switch reactivation after extinguishing in a short time unlike in the past, such as several seconds. Develop In the door.
      [0010]
      [Means for Solving the Problems]
  The "claim 1" relates to the lighting method of the high pressure discharge lamp (1) of the present invention.electrodeSupply lamp power toArc dischargeTo the point where the lamp temperature reaches the equilibrium temperature and the lamp temperature reaches the equilibrium temperature.electrodeShut off the current supply to the
      [0011]
  By doing this, when the switch is turned on immediately after extinguishing, and the high pressure discharge lamp (1) must be relighted during the transient state until the lamp temperature reaches the equilibrium temperature,electrodeA reduced current is supplied betweenArc dischargeIf you turn on the lighting current again,electrodeAmongArc dischargeThe momentary reviving returns to the stable lighting condition.
      [0012]
  On the other hand, in the transient stateArc dischargeAlthough the lamp temperature continues to decrease, the lamp temperature gradually decreases and reaches the equilibrium temperature after a predetermined time. And where the equilibrium temperature is reachedelectrodeThe current supply to the power supply is cut off, the lamp temperature decreases, and the lamp temperature reaches the relightable temperature. When the switch is turned on at this point, the normal means,electrodeApply the lighting start voltage betweenelectrodeIn the meantime, it is necessary to supply a lighting current to shift to stable lighting, but the standby time (t1) from turn off to turn on again is only about 5 seconds and the conventional Can be significantly shortened compared to seconds).
      [0013]
  When the target of use of such a high pressure discharge lamp (1) is a general household appliance such as a rear projection television (50) (of course, it is not limited thereto), the user switches the rear projection television (50)・ If the switch is turned on without any time in the transition period after off, the high pressure discharge lamp (1) can be instantly restored to the original brightness and the image can be projected on the screen (S). In the unlit state after the state elapses, even when the switch is turned on, it can be turned on again in a few seconds. In this point, it is not inferior to conventional televisions, and the user does not feel uncomfortable.
      [0014]
  Also, in the transitional state where the lighted state shifts to the lighted state,electrodeIn detailarcIf is formed,electrodeIt is kept above the evaporation temperature of mercury,electrodeIt does not condense even if mercury vapor contacts the surface of. On the other hand, since the sealed container (11) itself is cooled, the mercury vapor in contact with the inner surface of the light emitting tube (12) condenses on the inner surface of the light emitting tube (12) and gradually grows. The mercury vapor pressure in the arc tube portion (12) will be gradually reduced.
      [0015]
  And where the mercury vapor pressure in the luminous tube part (12) is sufficiently loweredelectrodeSince the supply current to the power supply is cut off, residual mercury vapor in the luminouselectrodeEven if it adheres to it, the amount is very small, so the formation of mercury bridge is eliminated 100% and it does not become an obstacle for relighting after extinguishing.
      [0016]
  "Claim 2" relates to the lighting method of the high pressure discharge lamp (1) used as the light source of the video equipment (A), "in the transition state where the lighting state is turned off, the screen is switched by switching off the video equipment (A) In addition to making (S) an image-free state, the power supplied to the high pressure discharge lamp (1) isArc dischargeReduce the lamp temperature to the equilibrium temperature and maintain the lamp temperature at the equilibrium temperature.electrodeShut off the current supply to the
      [0017]
  In the transient state after switching off the video equipment (A), the high pressure discharge lamp (1)arcIn the non-extinguished state, the high-pressure discharge lamp (1) glows with a certain amount of light, but the screen (S) of the video equipment (A) is not in an image state (for example, as described later ) (65G) (65B) does not transmit the white light from the high pressure discharge lamp (1)), so that the light from the high pressure discharge lamp (1) is not exposed from the screen (S) and it is・ It is possible to make it appear that it is off. When the switch is turned on again in this transient state, the high-pressure discharge lamp (1)Arc dischargeCan instantly return to a stable lighting state in a short time, and as described above, can make the image reappear on the screen (S) without being inferior to conventional televisions, and the user is not kept waiting. When the switch is turned on again in the light-off state after the transient state, as described above, the standby time (t1) can reappear an image on the screen (S) with about 5 seconds.
      [0018]
  The third aspect relates to the reduction amount of lamp power in the lighting method of the high pressure discharge lamp (1), characterized in that "the reduction amount of the lamp power is 1/2 to 1/20 of the rated output". . If the lamp power of this level is supplied, the high pressure discharge lamp (1) can be cooled by the normal fan (not shown).Arc dischargeAnd the lamp temperature is gradually decreased, and finally the relightable temperature (generally, in the case of a high pulse voltage of 10 kV to 15 kV for starting application voltage, about 400 ° C., 1 kV for starting application voltage In the case of a low DC voltage of 4 kV, the temperature can reach about 350 ° C. (see FIG. 1 (b)).
      [0019]
  [Claim 4] relates to a specific time of lamp power reduction performed in the lighting method of the high pressure discharge lamp (1) that "the reduction time (t2) of the reduced lamp power is 60 seconds or more"TheIt is a feature. The relighting possible temperature of the high pressure discharge lamp (1) depends on the start application voltage at the time of relighting, but is generally said to be about 400 ° C to about 330 ° C (in the case of high voltage of 10kV to 15kV) and (in the case of low voltage of 1kV to 4kV) ing. In addition, reduced lamp power by switching off according to the capacity of the high-pressure discharge lamp (1), the presence or absence of cooling, the starting lighting voltage to be applied, etc.Supply startFrom the equilibrium temperature (= generated by reduced lamp powerArc dischargeAlthough the reduction time (t2) to reach a certain level of equilibrium between the heat quantity supplied from the heat source and the heat quantity dissipated from the surface of the high-pressure discharge lamp (1) is not constant, The equilibrium temperature is reached above. In the case of low pressure, the equilibrium temperature is reached for about 60 seconds to 120 seconds (or, of course, may be 120 seconds or more). Therefore, by setting the time as a parameter, the high-pressure discharge lamp (1) can also determine the reduction time (t2) of the reduction lamp power by clocking with a timer such as a timer, or the high-pressure discharge lamp (1) The equilibrium temperature can also be analogized from a lamphouse (not shown) in which is housed and a thermometer (not shown) installed on the concave reflecting mirror (2).
      [0020]
  [Claim 5] is the lighting device (C) of the high pressure discharge lamp (1) for carrying out the above method [(a) high pressure pulse or low voltage direct current voltage is applied to the high pressure discharge lamp (1) A lighting start circuit (20), (b) a stable lighting circuit (21) connected to the lighting start circuit (20) to stably light the high pressure discharge lamp (1), (c) from the stable lighting circuit (21) Power control unit (22) for controlling power supply to the high pressure discharge lamp (1), and (d) a high pressure discharge lamp (1) from the stable lighting circuit (21) when the power control unit (22) is in stable lighting. In a transition state in which the stable lighting circuit (21) is controlled so that the stable supply of lighting power to the lamp is performed, and the high-pressure discharge lamp (1) transitions from stable lighting to extinguishing after switching off the video equipment (A), Lamp power to the high pressure discharge lamp (1)electrodeAmongArc dischargeAn optical engine that controls the stable lighting circuit (21) to focus on the lamp power to such an extent that the light does not disappear and sends an image to the screen (S) so as to make the screen (S) not an image simultaneously with the switch off. (E) is configured of a lamp power output reduction / optical engine control circuit (23) that outputs an image off signal.
      [0021]
  Optical engine (E)Figure 3In the lamp house (Ea), as shown in the example, the high-pressure discharge lamp (1) and an optical system including image elements (65R) (65G) (65B) such as a liquid crystal panel, The image elements (65R), (65G) and (65B) are controlled by the image element control unit (70). Note that the "state in which the screen (S) is not an image" refers to, for example, an off state in which the image elements (65R) (65G) (65B) are controlled to be light opaque and no image appears on the screen (S). .
      [0022]
  [Claim 6] [Claim 7] relates to the lighting start voltage in the lighting device (C) of the high pressure discharge lamp (1), and the former is characterized in that "the high voltage pulse to be applied is 10kV-15kV" The latter is characterized in that "the applied low voltage DC voltage is 1 kV to 4 kV". The former uses a conventional high pressure igniter (20 ')In the way, lighting start voltageSince it is high, it becomes easy to turn on again after turning off at high repeatable temperature. In other words, the reduction time (t2) can be shortened. On the other hand, the latter can continue by applying a low voltage DC voltageelectrodeEnergy required for dielectric breakdown between them can be supplied in a short time, and relighting after extinguishing can be relighted as well as when high-voltage pulses are applied.Can this kindIt can be said that it is the most preferable method as a lighting method. However, since the lighting start voltage is low, the relightable temperature becomes lower, and hence the reduction time (t2) becomes longer than the former.
      [0023]
  [Claim 8] relates to the video equipment (A) equipped with the lighting device (C), "(a) a screen (S) for projecting a video, (b) an optical engine for projecting a video on the screen (S) (E), (c) a high pressure discharge lamp (1) for supplying light to the optical engine (E), (d) a lighting start circuit (20) for applying a starting lighting voltage to the high pressure discharge lamp (1) The stable lighting circuit (21) which supplies the stable lighting power to the high pressure discharge lamp (1) at the time of stable lighting, and (e) until the high pressure discharge lamp (1) is cooled to the relighting possible temperature together with the switch off of the video equipment. Time (t2), the optical engine (E) is controlled to turn off the screen (S) and the high pressure discharge lamp (1) reaches the equilibrium temperature or the high pressure discharge lamp (1) reaches the equilibrium temperature A lamp power reduction / optical engine control circuit (23) for turning off the high pressure discharge lamp (1) after a considerable time (t2) which is supposed to be reached.
      [0024]
    BEST MODE FOR CARRYING OUT THE INVENTION
  Hereinafter, the present invention will be described in detail according to examples. FIG. 1 is a schematic cross-sectional view of a high pressure discharge lamp (1) to which the lighting method of the present invention is applied and a block diagram of an application lighting device (C). The high pressure discharge lamp (1) is mounted on a concave reflector (2) Used. The high pressure discharge lamp (1) is used for direct current lighting and for alternating current lighting.
      [0025]
  The circuit of the lighting device (C) includes a lighting start circuit (20), a stable lighting circuit (21), a power control unit (22), and a lamp power reduction / optical engine control circuit (23).
      [0026]
  The lighting start circuit (20) generates, for example, a low voltage DC voltage of about 1 kV to 4 kV and generates a low voltage circuit using this as a lighting starting voltage or generates a high voltage pulse of 10 kV to 15 kV and uses this as a lighting starting voltage and so on.
      [0027]
  The stable lighting circuit (21) is connected to the lighting start circuit (20), makes the high pressure discharge lamp (1) turn on stably when stable lighting, and turns to the high pressure discharge lamp (1) It is a circuit capable of throttling the supplied lamp power (see FIG. 1 (A)).
      [0028]
  The power control unit (22) controls so as to stabilize the supply of lighting power from the stable lighting circuit (21) to the high pressure discharge lamp (1) at the time of stable lighting, and in a transition period when stable lighting turns off This is a circuit that controls the stable lighting circuit (21) so as to throttle the lamp power supplied to the high pressure discharge lamp (1).
      [0029]
  The lamp power reduction and optical engine control circuit (23) controls the optical engine (E) to control the time until the high-pressure discharge lamp (1) reaches the equilibrium temperature (t2) by switching off the video equipment (A). The high-pressure discharge lamp (S) is turned into a non-image state, and when the high-pressure discharge lamp (1) reaches the equilibrium temperature or after an equivalent time (t2) when the high-pressure discharge lamp (1) reaches the equilibrium temperature 1) to turn off, the lamp power is restored to the stable lighting state when the switch of the video equipment (A) is turned on again, and the image is output from the optical engine (E) and the power control unit (22) and the optical engine (E) And a circuit for controlling the
      [0030]
  And the lamp control signal (including on / off) for performing on / off control of the high pressure discharge lamp (1) to the power control unit (22) and the high pressure discharge lamp in the transition from stable lighting to off. The output power supplied to (1) iselectrodeAmongArc dischargeAnd a lamp power reduction control signal for controlling the stable lighting circuit (21) so as to narrow the reduction lamp power to such an extent as not to disappear.
      [0031]
  The optical engine (E) is not limited to that shown in the present embodiment but various ones exist. The optical engine (E) shown in FIG. 3 will be described as a representative example. The optical engine (E) incorporates a high pressure discharge lamp (1) with a concave reflecting mirror (2), a color separation optical system, a projection lens (61) and the like in a lamp house (Ea). White light emitted from a high pressure discharge lamp (1) with a concave reflector (2) is separated into three colors of red (R), green (G) and blue (B) by dichroic mirrors (62) (63), Each color of red (R), green (G) and blue (B) is incident on an image element (65R) (65G) (65B) such as a liquid crystal panel through a condenser lens (64), and the image element control unit ( Red (R) and green (Y) incident on the image elements (65R) (65G) (65B) by changing the light transmittance of the image elements (65R) (65G) (65B) according to the respective image signals from 70). G) It is comprised so that each color of blue (B) may be interrupted | blocked and transmitted, and color light (H) may be radiate | emitted from a projection lens (61). Note that (67) and (68) are total reflection mirrors, and (69) and (66) are dichroic mirrors (semi-transmissive mirrors).
      [0032]
  FIG. 4 is a schematic cross section of a rear projection television (50) according to the present invention, provided on the front surface of a lighting device (C), an optical engine (E), a reflection mirror (M) housed inside a housing (50a). The color light emitted from the projection lens (61) of the optical engine (E) is reflected by the reflection mirror (M) and projected onto the screen (S). .
      [0033]
  Next, the operation of the lighting device (C) for low-pressure start lighting will be described according to the timing chart of FIG. When the switch (not shown) of the video equipment (A) in which the high pressure discharge lamp (1) is in the extinguished state is turned on, the video equipment (A) is activated and lamp start is performed. At this time point, the DC output outputted from the DC stable lighting circuit (21) starts the lighting start circuit (20) since the discharge lamp (1) is not lit, and a predetermined lighting start voltage (in the case of low voltage DC voltage) 1 kV to 4 kV or 10 kV to 15 kV in the case of a high voltage pulse voltage are generated and applied to the high pressure discharge lamp (1).
      [0034]
  As described above, after lamp start, go through glow dischargeArc dischargeTransition to is performed smoothly, and it shifts to stable lighting. Lamp voltage is from glow dischargeArc dischargeAfter having plunged in the early stage of transition to, the voltage gradually rises and reaches a predetermined voltage (for example, 80 V). Thereafter, the voltage is maintained and stable lighting is performed (in this case, rated power = 150 W, lamp surface temperature = 900 ° C.).
      [0035]
  As described above, the high-pressure discharge lamp (1) is turned on, but at the same time, the light quantity passing through each pixel constituting the image elements (65R), (65G) and (65B) is individually controlled by the image element control unit (70). The light is controlled and shut off, emitted from the projection lens (61), reflected by the reflection mirror (M), and projected onto the screen (S).
      [0036]
  Thereafter, when the video apparatus (A) is switched off, the lamp power reduction / optical engine control circuit (23) outputs a lamp power reduction control signal to the power control unit (22) at the same time as the image element control circuit ( 70), and the image elements (65R) (65G) (65B) are in the light blocking state. In this state, as described above, the high pressure discharge lamp (1)electrodeIn betweenArc dischargeThe image element (65R) (65G) (65B) is in a light blocking state, so the screen (S) is in a black screen off state. The user will think that the video equipment (A) has been switched off.
      [0037]
  In this transient state, the lamp control power (22) reduces the lamp power to a predetermined value,Arc dischargeIs kept small,Arc dischargeThe surface temperature of the high pressure discharge lamp (1) is gradually reduced by the cooling by the fan and finally reaches the equilibrium temperature. When the equilibrium temperature is reached, the lamp power supply is shut off and the high pressure discharge lamp (1) is turned off. Thereby, the high pressure discharge lamp (1) is rapidly cooled and reaches the relightable temperature in a few seconds. When the temperature of the relighting possible temperature is reached, when the switch of the video equipment (A) is turned on again, the high pressure discharge lamp (1) relights in a short time according to the above-mentioned procedure. In the present invention, the equilibrium temperature does not have to reach the equilibrium completely, but it also includes the state in which the cooling rate of the lamp surface is slow in practice.
      [0038]
  In the example of the figure, the reduction time (t2) of the supplied power is the case where the DC voltage of 2.4 KV is applied as the starting lighting voltage, the relightable temperature is 330 ° C., and the equilibrium temperature by the reduced lamp power The upper surface temperature of 12) is 350 ° C., and the reduction time (t2) to reach the equilibrium temperature is 2 minutes. Of course, the equilibrium temperature and the reduction time (t2) change depending on the capacity of the cooling state lamp and other conditions. When the reduction time (t2) passes, the high pressure discharge lamp (1) reaches the equilibrium temperature and the temperature does not decrease any further, so the off signal is input to the power control unit (22) and the lamp to the high pressure discharge lamp (1) After the power supply is cut off, the temperature drops rapidly and falls to the relightable temperature (330 ° C.) in about 5 seconds [standby time (t1)]. When the switch of the video equipment (A) is turned on in this state, the high pressure discharge lamp (1) is relighted in a short time as described above. In addition, during the reduction time (t2), stable lighting is restored in several seconds by the above-mentioned method at any time.
      [0039]
  Here, the equilibrium temperature is the upper surface temperature of the light emitting tube portion (12), but since this measurement is difficult in a practical machine, the reduction time (t2) is usually determined using the time parameter as described above However, when time is not used, the temperature of the concave reflecting mirror (2) is measured, and the upper surface temperature of the light emitting tube portion (12) is estimated therefrom.
      [0040]
  The change in the light emitting tube portion (12) in the case of relighting from extinguishing in the lighting method will be briefly described. The luminous tube portion (12) of the high-pressure discharge lamp (1) in the extinguished state is in a cooling state, and most of the mercury is accumulated in a spherical shape in the luminous tube portion (12),electrodeThere is almost no mercury adhering to the surface of. When start lighting is started,electrodeInsulation breakdown occurs betweenAn arc is generated between the electrodes.
      [0041]
  StableAfter the formation of the arc spot, the lamp voltage increases as the mercury evaporates, and after several minutes, the lamp turns on stably at the rated power. On the other hand, the optical engine (E) operates together with the lamp lighting, and projects and projects an image on the screen (S).
      [0042]
  When the use of the video device (A) is finished, the user turns off the video device (A), but the high pressure discharge lamp (1) is not turned off immediately, and the power control unit (22) is first switched off. A lamp power reduction control signal is input. When the lamp power reduction control signal is input, the power control unit (22) reduces the output power to a preset reduced lamp power and maintains the reduced lamp power for a reduction time (t2).electrodeBetweenArc dischargeMaintain the During this time, the high pressure discharge lamp (1) is subjected to forced air cooling, so it generates an arc part and an arc.electrodeIs maintained at a high temperature, but the arc tube portion (12) is cooled to such an extent that mercury condenses, and the vapor mercury existing outside the portion contacting with the arc portion and the electrode surface is cooled Set in contact with the inner surface of 12).
      [0043]
  At this time, the lower the reduced lamp power, the lower the lamp temperature, the faster the condensation of mercury can be made, and the time to turn off can be shortened.arcIt is necessary to maintain the lamp power so as not to go out.
      [0044]
  The standard is 1/2 to 1/20 of the rated power, and if the reduced lamp power in the transition period is 1/2 of the rated power, mercury vapor can be condensed if forced air cooling is available, and if 1/20. The arc may go out and at least a reduced lamp power of at least 1/20 is required. Normally, the reduced lamp power is supplied at about 1⁄5, and when the rated output of the high pressure discharge lamp (1) is 270 W, a reduced lamp power of about 50 W is supplied.
      [0045]
  In the transition period from stable lighting to extinguishing as in the present invention, the reduced lamp power is much smaller than the rated power as described above for a certain period.electrodeSupply toarcMaintain theelectrodeRemoval of the mercury bridge by reducing the adhesion of mercury to the surface of theelectrodeRealize short-term evaporation of mercury on the surface of thearcBreakthrough travel timeMake it shortThere is also an advantage that it is possible to minimize the probability of arc extinguishing at the start of lighting and to eliminate the risk of blackening.
      [0046]
    【Effect of the invention】
  According to the present invention, the arc discharge is maintained in the transition state from the lighting state to the extinguishing state. Therefore, when the switch is turned on immediately after the extinguishing, the arc discharge recovers immediately and returns to the stable lighting state. When it is used as a light source of such general household appliances, it is possible to project an image on the screen similar to a television assuming that it is switched on immediately after being switched off.
      [0047]
  In addition, since the screen is turned off by switching on the video equipment in the transitional state in which the lighting state is turned off, even if the high pressure discharge lamp emits weak light in the transitional state, it does not appear in the image, You can make it appear as if it were switched off. If the switch is turned on again in this transient state, as described above, it is possible to make the picture reappear on the screen in a short time as in the conventional television.
Brief Description of the Drawings
  [Fig. 1]
  A block circuit diagram of a lighting device to which the present invention is applied
  [Fig. 2]
  Block circuit diagram of a conventional lighting device
  [Fig. 3]
  Conceptual diagram of the optical engine used in the present invention
  [Fig. 4]
  Schematic sectional drawing of the rear projection television of this invention
  [Description of the code]
  (A) Video equipment
  (C) Lighting circuit
  (D) Optical engine
  (1) High pressure discharge lamp
  (2) Concave reflector
  (11) Sealed container
  (12) Luminescent tube

Images