JP2007059281A - High-pressure discharge lamp lighting device and image display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the damage of an arc tube and the failure of a lamp lighting device by improving an abnormality detecting function of a high-pressure discharge lamp lighting device used for turning on a short-arc high-pressure discharge lamp. <P>SOLUTION: This high-pressure discharge lamp lighting device comprises a lamp lighting circuit 2 for supplying a predetermined power to a discharge lamp 3 by using switching elements; a starting circuit 4 for lighting a discharge lamp 3; a detection circuit 5 for detecting a lamp voltage; a judgment means for determining the discharge lamp 3 to be an abnormality if a detected lamp voltage is lower than a predetermined voltage; an abnormality processing means for controlling the high-pressure discharge lamp 3 when determining that an abnormality occurs; and a time detection circuit 7 for detecting a time period elapsing after turning off of the discharge lamp 3. A starting time is turned off at which determining that an abnormality occurs is changed depending on an elapsed time from when the discharge lamp 3 is turned off. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a high pressure discharge lamp lighting device for lighting a high pressure discharge lamp, and an image display device using the same.

  In a projector using a liquid crystal or the like, a projection television receiver, and the like, a small high-pressure discharge lamp having a distance between electrodes of 5 mm or less is used. This type of discharge lamp is desired to be a point light source from the viewpoint of optical design, and is shortened to about 1 mm.

A discharge lamp lighting device for lighting these lamps is known to detect an abnormality and reduce or cut off lamp power when a slow leak occurs, as described in, for example, Japanese Patent Laid-Open No. 10-275692. It has been.
Japanese Patent Laid-Open No. 10-275692

  However, in the above-described conventional configuration, when the lamp voltage of the high pressure discharge lamp rises above the first reference voltage and then falls below the second reference voltage, the high pressure discharge lamp is determined to be abnormal, and the high pressure discharge lamp Reduce or cut off the power supplied to the. Therefore, if the lamp voltage of the high-pressure discharge lamp does not rise to the first reference voltage, this protection function will not operate.

  In a high pressure discharge lamp with a short arc length used in an image display device, the discharge lamp is usually air-cooled by a fan (see FIG. 12). However, if this temperature control is not properly performed, the arc tube portion expands. As a result, the lamp voltage decreases. If lighting is continued in such a lamp abnormal state, the arc tube may be damaged. There is a need to take measures to prevent the lamp from being damaged in any case including a restart (hot restart) in which the arc tube is turned on in a warm state.

  Furthermore, since the arc length is as short as about 1 mm, the electrodes may be short-circuited when mercury in the arc tube liquefies after the lamp is extinguished. When the high pressure discharge lamp is turned on in this state, a current flows between the short-circuited electrodes. Therefore, the protection function does not operate, and a current that greatly exceeds the lamp current at the time of rated lighting continues to flow. As a result, if such an abnormal current continues, the high pressure discharge lamp lighting device may break down.

  In order to solve the above problem, the invention of claim 1 starts the discharge lamp 3 and the lighting circuit 2 for supplying predetermined power to the discharge lamp 3 using a switching element as shown in FIGS. A starting circuit 4 for detecting the lamp voltage, a detecting circuit 5 for detecting the lamp voltage, and means for determining that the discharge lamp 3 is abnormal when the detected lamp voltage is equal to or lower than the reference voltage (processing step # 8 of the control circuit 6). , A high pressure discharge lamp lighting device comprising an abnormality processing means (control step # 9 of the control circuit 6) for performing control when it is determined to be abnormal, and a detection circuit 7 for detecting an elapsed time after the discharge lamp 3 is turned off. , The abnormality determination start time t0 is changed according to the elapsed time after the discharge lamp 3 is turned off.

  As shown in FIG. 1, the invention of claim 2 is a lighting circuit 2 for supplying predetermined power to the discharge lamp 3 using a switching element, a starting circuit 4 for starting the discharge lamp 3, and a lamp voltage detection. A high-pressure discharge lamp lighting device comprising: a detection circuit 5 that performs detection; a unit that determines that the discharge lamp 3 is abnormal when the detected lamp voltage is equal to or lower than a reference voltage; and an abnormality processing unit that performs control when it is determined to be abnormal. As shown in FIG. 5, the reference voltage for determining that the discharge lamp 3 is abnormal varies depending on the time after the discharge lamp 3 is turned on.

The invention of claim 3 is characterized in that, in claims 1 and 2, there are provided a plurality of means (# 8 ′, # 8 ″ in FIG. 8) for judging abnormality of the discharge lamp.
The invention of claim 4 is characterized in that, in claim 3, at least one of the abnormality judging means (# 8 'in FIG. 8) immediately judges that an abnormality is present when the detected lamp voltage is lower than the reference voltage. And
According to a fifth aspect of the present invention, in the third aspect, at least one of the abnormality determination means (# 8 ″ in FIG. 8) indicates that an abnormality is detected when the detected lamp voltage is below the reference voltage for a predetermined time. Judgment is made (# 10 to # 12 in FIG. 8).

According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the high pressure discharge lamp is a short arc high pressure discharge lamp.
Invention of Claim 7 is the discharge lamp lighting device in any one of Claims 1-6, the high pressure discharge lamp provided with the reflector, The image display means which displays an image using the light of a discharge lamp, An optical system for condensing the light that has passed through the image display means and projecting it on a screen, and a case for housing these components are provided.

According to the first aspect of the present invention, since abnormality detection can be performed earlier, including during hot restarts, it is possible to prevent damage to the arc tube and failure of the discharge lamp lighting device.
According to the second aspect of the present invention, since the reference voltage for determining that the discharge lamp is abnormal changes according to the lighting time of the discharge lamp, it is effective when the lamp voltage rises slowly.

According to the invention of claim 3, since the optimum processing at the time of abnormality suitable for different abnormality modes such as a short circuit and a slow leak is performed, it can be reliably detected.
In the invention of claim 4, since abnormality is immediately determined, the high pressure discharge lamp lighting device can be quickly stopped to prevent the lighting circuit from being destroyed.
In the invention of claim 5, malfunction of abnormality detection due to noise can be prevented.

In the invention of claim 6, a desired high pressure discharge lamp lighting device can be provided.
The invention of claim 7 can provide an image display device having the effects of the inventions of the above claims.

(Embodiment 1)
FIG. 1 is a block diagram showing a basic configuration of a high pressure discharge lamp lighting device according to Embodiment 1 of the present invention. A lighting circuit 2 connected to the DC power source 1, a starting circuit 4 for lighting the lamp 3, a detection circuit 5 for detecting the lamp voltage, a control circuit 6 for controlling the power of the lamp 3, and a lamp unlit elapsed time It consists of a detection circuit 7.

  When the power is turned on, a high voltage is generated by the starting circuit 4 and the lamp 3 is turned on. When the lamp 3 is turned on, the lamp voltage and the lamp current are detected, and control is performed so that predetermined power is supplied to the lamp 3. When the power is turned on, the capacitor C0 for detecting the lamp turn-off elapsed time is charged, and when the power is turned off, the charge accumulated in the capacitor C0 is discharged. When the power is turned on again, if the electric charge remains in the capacitor C0, the voltage can be detected to know the time when the lamp 3 is turned off. If the voltage of the capacitor C0 is 0, it can be seen that a sufficient time has elapsed since the lamp 3 was turned off.

  The connected DC power supply 1 is not limited to a battery, but may be a substantially constant DC power supply generated by a converter circuit connected to an AC power supply. The lighting circuit 2 and the starting circuit 4 may be a combination of known circuits. The lamp turn-off elapsed time detection circuit 7 is not limited to the illustrated circuit, and a large-capacity power supply circuit may be connected to the control circuit 6 and the time may be counted using a timer of a microcontroller. In this case, when the power of the discharge lamp lighting device is turned on, if the output voltage of the power supply circuit connected to the control circuit 6 is equal to or lower than the operating voltage of the microcontroller, a sufficient time elapses after the lamp 3 is turned off. You can see that

  FIG. 2 shows a flowchart for explaining the operation of the microcontroller of the control circuit 6. When the power is turned on and the lamp is lit, the lamp lighting time t starts to be counted (# 1). The voltage of the lamp extinction time detection capacitor C0 is read (# 2). Since the lamp turn-off elapsed time is known according to the read voltage, the start time t0 of the low lamp voltage stop function is set based on this (# 3).

  FIG. 3 shows an example of the relationship between the voltage of the capacitor C0 and the start time t0 of the low ramp voltage stop function. The relationship shown in FIG. 3 is stored as a memory table in the microcontroller of the control circuit 6, and the start time t0 of the low ramp voltage stop function is set according to the voltage of the capacitor C0 subjected to A / D conversion. If the voltage of the capacitor C0 is V4 or less, when the power is turned on, a sufficient time has passed since the lamp is extinguished.

  A power command value to be supplied to the lamp is set, and the lamp voltage Vla is read (# 4, # 5). If t <t0, lamp lighting control is performed (# 6, # 7), and if not, it is determined whether Vla exceeds VL (# 8). If it exceeds, lighting control (# 7) is performed, and if it does not exceed, the operation is stopped (# 9).

  FIG. 4 shows the relationship between the lamp voltage Vla and the lamp lighting time. Here, the high lamp voltage detection voltage VH is a reference voltage for stopping the operation when the lamp voltage rises significantly exceeding the rating at the end of the lamp life.

  In so-called hot restart, in which the lamp is lit in a warm state, the lamp voltage rises faster than in cold start. Therefore, the lamp abnormality can be detected in a short time by advancing the start time t0 of the low lamp voltage stop function at the time of hot restart.

  In this flowchart, lighting control is stopped when the low lamp voltage stop function is operated, but lighting may be maintained at a power lower than the rated power of the lamp without stopping. In this case, since the lamp voltage further decreases when the lamp is lit with power lower than the rated value, it is necessary to stop the low lamp voltage stop function or lower the low lamp voltage detection voltage VL.

(Embodiment 2)
FIG. 5 shows the operating range of the low lamp voltage and high lamp voltage stop function of the second embodiment. The circuit configuration is the same as in the first embodiment. The detection voltage of the low lamp voltage stop function sets VL1 to a low value for short circuit protection between the electrodes immediately after the lamp is turned on. If the lamp is normal, the lamp voltage gradually increases after lighting. Therefore, if the lamp voltage is set to exceed VL2 at t2 after the lamp is lit, lamp abnormality due to slow leak or arc tube bulge can be detected quickly, and the high voltage The discharge lamp lighting device can be safely stopped.

(Embodiment 3)
FIG. 6 shows the operating range of the low lamp voltage and high lamp voltage stop function of the third embodiment. The circuit configuration is the same as in the first embodiment. From the lamp lighting time t1 to t2, in order to protect the lamp between the electrodes, the lighting device is immediately stopped once it falls below the low lamp voltage detection voltage VL (period A). On the other hand, after t2, the lighting device is stopped when the lamp is abnormal due to slow leak or arc tube bulging. Therefore, the lighting control is stopped for the first time when the state of being lower than VL continues for a predetermined time. If VL is exceeded again in time, the abnormality processing routine is canceled (period B). Due to the control during this abnormal processing, the internal material of the high-pressure discharge lamp with a short arc length grows on the electrodes by the halogen cycle, the distance between the electrodes is shortened, and the lamp voltage is temporarily reduced. It is possible to prevent the lamp from being turned off.

  Thus, in the case where there are a plurality of means for determining the abnormality of the discharge lamp, if the plurality of abnormality determination means are switched according to the lamp lighting time, the abnormality determination means according to the change of the lamp voltage according to the lighting time. By switching, abnormality detection can be reliably performed with few malfunctions.

(Embodiment 4)
FIG. 7 shows the operating range of the low lamp voltage and high lamp voltage stop function of the fourth embodiment. The circuit configuration is the same as in the first embodiment. FIG. 8 shows a flowchart for explaining the operation of the fourth embodiment of the present invention. When the power is turned on and the lamp is lit, the lamp lighting time t starts to be counted (# 1). The voltage of the lamp extinction time detection capacitor C0 is read (# 2). The lamp turn-off elapsed time is set according to the read voltage (# 2 ′), and the slow leak stop function start time t2 is set based on the lamp turn-off elapsed time (# 3).

  A power command value to be supplied to the lamp is set (# 4), and if t <t1 (# 6 '), lighting control (# 7) is performed. If t ≧ t1, the lamp voltage Vla is read (# 5). If t <t2 (# 6 ″), it is determined whether Vla exceeds VL1 (# 8 ′). If t ≧ t2, it is determined whether Vla exceeds VL2 (# 8 ″). . If Vla ≦ VL2, start the abnormal count (# 11), if the abnormal count is within the abnormal detection set time (# 12), continue the lighting control (# 7), otherwise stop the operation (# 9). If Vla> VL2 in the middle of the abnormality count, the abnormality count is canceled (# 10) and the lighting control (# 7) is continued.

  The low lamp voltage detection voltage VL1 is set to an extremely low value for short-circuit protection between the electrodes of the lamp, and this function start time t1 is also set to operate immediately after lighting. In the case of a short circuit, since the current significantly exceeds the rated current of the lamp flows, the loss of the switching element of the lighting circuit becomes large and may be destroyed even in a short time, so the lighting device is immediately stopped if it falls below VL1 after t1. To do.

  On the other hand, VL2 is set to a relatively high voltage in order to stop the lighting device when the lamp is abnormal due to slow leak or arc tube bulge, and the operation start time is also set to several minutes after the lamp is lit. Control at the time of an abnormality below VL2 after t2 after the lamp is lit stops the lighting control for the first time when the state of being below VL2 continues for a predetermined time, and even if it falls below VL2, VL2 can be exceeded again within the predetermined time. If the error processing routine is cancelled, the abnormal processing routine is canceled. Due to the control during this abnormal processing, the internal material of the high-pressure discharge lamp with a short arc length grows on the electrodes by the halogen cycle, the distance between the electrodes is shortened, and the lamp voltage is temporarily reduced. It is possible to prevent the lamp from being turned off.

  As described above, in the case where there are a plurality of means for judging abnormality of the discharge lamp, if the plurality of abnormality judgment means are switched according to the lamp lighting time, the abnormality judgment is made according to the change of the lamp voltage according to the lighting time. By switching the means, it is possible to reliably detect an abnormality with few malfunctions. Further, if there are a plurality of reference voltages that are determined to be abnormal by the discharge lamp in accordance with a plurality of abnormality determination means, a reference voltage at which the discharge lamp is determined to be abnormal can be set in accordance with the behavior of the lamp voltage. It is possible to reliably detect an abnormality. Furthermore, the abnormality can be reliably detected by setting the switching of the reference voltage at which the discharge lamp is determined to be abnormal at different times. Note that t1 and t2 may be set at the same time.

(Embodiment 5)
FIG. 9 shows the operating range of the low lamp voltage and high lamp voltage stop function of the fifth embodiment. FIG. 10 shows a configuration for detecting an elapsed time after the discharge lamp is turned off as an example different from FIG. In the present embodiment, a detection circuit 7 that detects an elapsed time after the discharge lamp 3 is turned off is provided, and the abnormality determination start time t0 is changed according to the elapsed time after the lamp is turned off. Abnormality can be detected reliably even at the start.

  In this embodiment, a large-capacitance capacitor C1 is connected to the control circuit 6, and when the power is turned on, the capacitor C1 is charged, and the microcontroller of the control circuit 6 operates for a long time after the power is turned off. Meanwhile, the extinguishing time of the discharge lamp 3 is counted by a timer of the microcontroller. If the power is turned on again, the low lamp voltage stop function start time t0 is set according to the counted turn-off time. If the voltage of the capacitor C1 is lower than the operating voltage of the microcontroller, it can be determined that a sufficiently long time has elapsed since the lamp 3 was turned off. The start time tcold of the stop function is set.

  In the above embodiment, the image display apparatus may change the power when the lamp is stably lit in order to adjust the amount of light projected onto the screen according to the usage environment. At this time, since the temperature of the arc tube of the discharge lamp is different, the way of increasing the lamp voltage at the time of hot restart is different. Therefore, the abnormality determination start time t0 is changed according to the elapsed time since the discharge lamp is extinguished according to the power supplied to the discharge lamp. When the lamp power is small, the temperature rise of the arc tube is small. Therefore, when the hot restart is performed at the same elapsed time as when the power is large, the abnormality determination start time is advanced.

(Embodiment 6)
The discharge lamp lighting device of each of the above-described embodiments is used for lighting a discharge lamp serving as a light source of an image display device such as a projector or a rear projection TV. Here, the case where it mounts in a projector is illustrated. FIG. 11 is a perspective view showing the external appearance of the image display device 30, and FIG. 12 is a schematic configuration diagram showing the internal configuration of the image display device 30. In the figure, 31 is a projection window, 32 is a power supply unit, 33a, 33b and 33c are cooling fans, 34 is an external signal input unit, 35 is an optical system, 36 is a main control board, 40 is a discharge lamp lighting device, 3 Is a discharge lamp. A main control board 36 is mounted in a frame indicated by a broken line. As described above, the discharge lamp 3 is mounted inside the image display device 30. However, by adopting the discharge lamp lighting device 40 of the present invention, the abnormality detection can be performed earlier than in the prior art. Failure of the discharge lamp lighting device can be prevented.

It is a block diagram which shows the basic composition of the high pressure discharge lamp lighting device of Embodiment 1. 3 is a flowchart showing the operation of the first embodiment. It is a figure which shows the relationship between the capacitor voltage for lamp extinction elapsed time detection of Embodiment 1, and the low lamp voltage stop function start time. It is a figure which shows the relationship between the lamp lighting time of Embodiment 1, and a lamp voltage. It is a figure which shows the relationship between the lamp lighting time of Embodiment 2, and a lamp voltage. It is a figure which shows the relationship between the lamp lighting time of Embodiment 3, and a lamp voltage. It is a figure which shows the relationship between the lamp lighting time of Embodiment 4, and a lamp voltage. 10 is a flowchart showing the operation of the fourth embodiment. It is a figure which shows the relationship between the lamp lighting time of Embodiment 5, and a lamp voltage. FIG. 10 is a block diagram illustrating a basic configuration of a lighting device according to a fifth embodiment. FIG. 10 is a perspective view illustrating an appearance of an image display device according to a sixth embodiment. FIG. 10 is a schematic configuration diagram showing an internal configuration of an image display device according to a sixth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC power supply 2 Lighting circuit 3 High pressure discharge lamp 4 Starting circuit 5 Lamp voltage detection circuit 6 Control circuit 7 Lamp extinction time detection circuit

Claims (7)

When a lighting circuit that supplies a predetermined power to the discharge lamp using a switching element, a starting circuit for starting the discharge lamp, a detection circuit that detects the lamp voltage, and when the detected lamp voltage is below the reference voltage In a high pressure discharge lamp lighting device comprising a means for determining that a discharge lamp is abnormal, an abnormality processing means for performing control when it is determined to be abnormal, and a detection circuit for detecting an elapsed time after the discharge lamp is extinguished. A high pressure discharge lamp lighting device characterized in that the start time of abnormality determination is changed according to the elapsed time after the lamp is turned off. When a lighting circuit that supplies a predetermined power to the discharge lamp using a switching element, a starting circuit for starting the discharge lamp, a detection circuit that detects the lamp voltage, and when the detected lamp voltage is below the reference voltage In the high-pressure discharge lamp lighting device having means for determining that the discharge lamp is abnormal and abnormality processing means for performing control when it is determined to be abnormal, the reference voltage for determining that the discharge lamp is abnormal depends on the lighting time of the discharge lamp. A high pressure discharge lamp lighting device characterized by changing. 3. The high pressure discharge lamp lighting device according to claim 1, comprising a plurality of means for judging abnormality of the discharge lamp. 4. The high pressure discharge lamp lighting device according to claim 3, wherein at least one of the abnormality determining means immediately determines that the abnormality is present when the detected lamp voltage is equal to or lower than the reference voltage. 4. The high pressure discharge lamp lighting device according to claim 3, wherein at least one of the abnormality determining means determines that an abnormality occurs when a state in which the detected lamp voltage is equal to or lower than a reference voltage continues for a predetermined time. 6. The high pressure discharge lamp lighting device according to claim 1, wherein the high pressure discharge lamp is a short arc high pressure discharge lamp. The high pressure discharge lamp lighting device according to any one of claims 1 to 6, a high pressure discharge lamp including a reflector, an image display unit that displays an image using light of the discharge lamp, and an image display unit An image display device comprising: an optical system for condensing light and projecting it on a screen; and a case for housing these components.

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