JP2006120654A - Discharge lamp lighting device and projector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a discharge lamp lighting device in which occurrence of flicker and deterioration of an electrode are suppressed by keeping proper temperature of the electrode and an inside of a bulb by simple control. <P>SOLUTION: A DC-DC converter circuit 1 equipped with a switching element Q1 makes the power supply to a high-brightness discharge lamp La vary. Switching of the switching element Q1 of the converter circuit 1 is controlled by a control circuit 3. The control circuit 3 controls the switching of the switching element Q1 of the converter circuit 1 with a constant power mode in which the constant power is supplied to the discharge lamp La in lighting stably the discharge lamp La. Furthermore the control circuit 3 increases a lamp current and has an power increasing mode increasing a lamp current supplied from the converter circuit 1 in a period of at least one half cycle of a rectangular wave voltage in a unit period and also increasing the actual value of the supply power more than that of in the constant power mode during the lighting period of the discharge lamp La. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a discharge lamp lighting device used for lighting a high-intensity discharge lamp and a projector equipped with the discharge lamp lighting device.

  2. Description of the Related Art Conventionally, there is known a discharge lamp lighting device for lighting a discharge lamp by applying a rectangular wave alternating voltage. In particular, in a high-intensity discharge lamp (HID lamp) such as an ultra-high pressure mercury lamp used as a light source for a projector, a rectangular wave alternating with a relatively low frequency (several hundred Hz) is used to prevent the occurrence of an acoustic resonance phenomenon. A configuration for applying a voltage is widely employed (see, for example, Patent Document 1).

  In this type of application, it is required to make the arc length of the discharge lamp as small as possible in order to approach the point light source. However, when the arc length is reduced, the arc generation position on the electrode becomes unstable depending on the temperature of the electrode and the surface condition, and the phenomenon that the starting position of the arc jumps to another place tends to occur. When this type of phenomenon occurs, flicker occurs in the light output from the discharge lamp, and when used as a light source for a projector, the brightness on the projection surface (screen) decreases or the brightness varies. This causes problems such as difficulty in viewing images.

  By the way, when the lamp voltage of the discharge lamp is high, the lamp current is reduced, and the temperature in the electrode of the discharge lamp and the bulb is lowered, so that the activity in the bulb is lowered. For example, in the case of a metal halide lamp, the halogen cycle is not actively performed. Normally, a projection is formed on the surface of the electrode, and the projection becomes the starting point of the arc, so that the starting point of the arc is stabilized. However, as described above, a projection is formed on the surface of the electrode when the activity in the bulb is reduced. It is difficult to cause a phenomenon in which the starting point of the arc moves without being determined. Further, if the projections are not formed on the surface of the electrode and the starting point of the arc is not stable, the entire electrode is damaged by the arc, so that the deterioration of the electrode easily proceeds.

By the way, as a technique for reducing flicker of the discharge lamp La, a technique for changing the lamp current shape of the discharge lamp La according to detection of occurrence of flicker has been proposed (for example, see Patent Document 2). In addition, a technique has been proposed in which the instantaneous value of the power supplied to the discharge lamp is gradually increased over time in a half cycle of the lamp current of the discharge lamp (see, for example, Patent Document 3).
JP 2002-352882 A (paragraph 0009-0013, FIG. 1) Japanese translation of PCT publication No. 2002-532866 (paragraph 0013, FIG. 1) JP 2002-134287 A (paragraphs 0019-0020, FIG. 1-2)

  The techniques described in Patent Documents 1 and 2 described above are techniques for controlling electrode wear, and Patent Document 2 focuses particularly on reducing flicker, but in order to change the lamp current shape of the discharge lamp. There is a problem that it is necessary to superimpose a pulsed current, and relatively complicated control is required. Similarly, the technique described in Patent Document 3 also changes the instantaneous value of the power supplied to the discharge lamp and changes the waveform of the voltage or lamp current applied to the discharge lamp to a waveform other than a rectangular wave. Has the problem of requiring complicated control.

  The present invention has been made in view of the above-mentioned reasons, and its purpose is to enable the temperature of the discharge lamp electrode and bulb to be kept in an appropriate state by simple control, and thus to generate protrusions on the electrode. This provides a discharge lamp lighting device that stabilizes the position of the starting point of the arc and suppresses the generation of flicker and suppresses the deterioration of the electrode, thereby extending the life of the discharge lamp. The object is to provide a projector equipped with an electric lamp lighting device.

  According to a first aspect of the present invention, there is provided a power conversion circuit in which power supplied to a discharge lamp, which is a high-intensity discharge lamp, is variable by controlling on / off of a switching element, and constant power is supplied to the discharge lamp when the discharge lamp is stably lit. The control circuit for controlling on / off of the switching element of the power conversion circuit in the constant power mode is a unit period in which the polarity of the rectangular wave voltage applied to the discharge lamp is reversed a specified number of times, and the rectangular wave voltage is changed within the unit period. A high power mode that increases the lamp current supplied from the power conversion circuit in at least one half-cycle period than in other periods can be selected during the discharge lamp lighting period after the discharge lamp has shifted to stable lighting. A high power mode is provided with a power increase mode for increasing the effective value of power supplied to the discharge lamp as compared to the constant power mode. .

  According to this configuration, it is possible to keep the temperature of the electrode of the discharge lamp and the bulb in an appropriate state by simple control that only changes the lamp current supplied to the discharge lamp. It is possible to promote the generation and stabilize the position of the starting point of the arc, thereby suppressing the generation of flicker and further suppressing the deterioration of the electrode, thereby extending the life of the discharge lamp. In addition, in the high power mode, since a period for increasing the lamp current is provided for each unit period, the temperature of the electrode of the discharge lamp can be maintained, and the light output can be stabilized. Furthermore, since the high power mode includes a power increase mode that increases the effective value of power compared to the constant power mode, for example, the effect of suppressing the occurrence of flicker is enhanced.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control circuit is characterized in that a half cycle time during which the lamp current is increased as compared with other periods is different from the other half cycle time.

  According to this configuration, not only the lamp current is increased, but also the time for increasing the lamp current is adjusted, so that it is difficult to achieve both the conformity to the specifications of the discharge lamp and the maintenance of the electrode temperature with the lamp current alone. Even in this case, it can be handled by adjusting the time.

  According to a third aspect of the invention, in the first or second aspect of the invention, the control circuit changes the frequency of the rectangular wave voltage when a specific transition condition is satisfied in the high power mode. To do.

  According to this configuration, not only the lamp current is increased, but also the frequency of the rectangular wave voltage is adjusted. Therefore, it is difficult to achieve both the conformity to the specifications of the discharge lamp and the temperature of the electrode with the lamp current alone. Even in this case, it can be handled by adjusting the frequency.

  According to a fourth aspect of the invention, in the first or second aspect of the invention, the control circuit changes the frequency of increasing the lamp current when a specific transition condition is satisfied in the high power mode. And

  According to this configuration, not only the lamp current is increased, but also the frequency at which the lamp current is increased is adjusted. Therefore, it is difficult to achieve both compatibility with the specifications of the discharge lamp and keeping the electrode temperature with the lamp current alone. Even in this case, it can be dealt with by adjusting the frequency of increasing the lamp current.

  According to a fifth aspect of the invention, in the first or second aspect of the invention, the control circuit changes a peak value of a lamp current when a specific transition condition is satisfied in the high power mode. To do.

  According to this configuration, not only the lamp current is increased, but also the peak value of the lamp current is adjusted, so that it is difficult to achieve both the conformity to the specification of the discharge lamp and the temperature of the electrode only by the lamp current. Even in this case, it can be dealt with by adjusting the peak value of the lamp current.

  According to a sixth aspect of the invention, in the first or second aspect of the invention, the control circuit increases the frequency of the rectangular wave voltage and the lamp current when a specific transition condition is satisfied in the high power mode. And two or more elements of the lamp current peak value are changed.

  According to this configuration, since two or more kinds of the adjustment elements according to any one of claims 3 to 5 are combined, the adjustment range is further widened.

  According to a seventh aspect of the invention, in any one of the first to sixth aspects of the invention, the discharge lamp is used as a light source, and the projector is provided with a color filter in which a transmitted color of light from the light source changes with time in a specified cycle. In the discharge lamp lighting device, the control circuit synchronizes the timing of reversing the polarity of the rectangular wave voltage applied to the discharge lamp with the timing of changing the transmission color of the color filter.

  According to this configuration, when a discharge lamp is used as a light source of a projector that presents a color image by changing the transmission color of the color filter with a predetermined period of time, the light output from the light source at the timing of switching the polarity of the rectangular wave voltage The light from the light source is used efficiently as the transmitted light of each color region of the color filter without using the light during the period when the light is decreasing. .

  The invention of claim 8 is a projector, characterized in that the discharge lamp lighting device according to any one of claims 1 to 7 is mounted.

  According to the configuration of the present invention, simple control that only changes the lamp current supplied to the discharge lamp while allowing the high power mode to be selected during the stable lighting period in which constant power is supplied to the discharge lamp in the constant power mode. This makes it possible to keep the temperature of the discharge lamp electrode and bulb in an appropriate state, and consequently, it is possible to promote the formation of protrusions on the electrode and stabilize the position of the starting point of the arc, thereby suppressing the occurrence of flicker In addition, there is an advantage that the life of the discharge lamp can be extended by suppressing the deterioration of the electrode. In addition, in the high power mode, since a period for increasing the lamp current is provided for each unit period, there is an advantage that the temperature of the electrode of the discharge lamp can be maintained and the light output can be stabilized. Further, since the high power mode includes a power increase mode that increases the effective value of power compared to the constant power mode, there is an advantage that, for example, the effect of suppressing the occurrence of flicker is enhanced.

(Basic configuration 1)
In this example, as shown in FIG. 1, a DC-DC conversion circuit 1 using a DC power supply E as a power supply, and a DC voltage output from the DC-DC conversion circuit 1 is converted into a rectangular wave alternating voltage to generate a discharge lamp La. And a control circuit 3 that controls on / off of the switching elements Q1 to Q5 provided in the power conversion circuit. The switching elements Q1 to Q5 are selected from power transistors, MOSFETs, and IGBTs. Further, as the discharge lamp La, a high-intensity discharge lamp, for example, a 120 to 300 W ultrahigh pressure mercury discharge lamp is used. An igniter that generates a high voltage for starting the discharge lamp La is not shown.

  The DC-DC conversion circuit 1 is a step-down chopper circuit in the illustrated example, and a switching element Q1 and a diode D1 are connected in series between both ends of a DC power source E (or a DC power source obtained by rectifying an AC power source). A circuit is inserted, and a series circuit of a smoothing capacitor C1 and an inductor L1 connected between output terminals of the DC-DC conversion circuit 1 is connected in parallel to a diode D1. The cathode of the diode D1 is connected to the connection point between the switching element Q1 and the inductor L1, and the anode of the diode D1 is connected to the negative electrode of the smoothing capacitor C1. As is well known, this chopper circuit allows a charging current to flow from the DC power source E to the smoothing capacitor C1 through the inductor L1 during the ON period of the switching element Q1, and passes through the smoothing capacitor C1 and the diode D1 during the OFF period of the switching element Q1. The energy of the inductor L1 is discharged through the path. An input current detection resistor R1 is inserted between the negative electrode of the DC power supply E and the anode of the diode D1, and the series circuit of the smoothing capacitor C1 and the resistor R1 is a series circuit of two resistors R2 and R3. The voltage dividing circuit 4 is connected in parallel. Here, since it is assumed that the DC power source E has a higher voltage than the lighting voltage of the discharge lamp La, a step-down chopper circuit is used, but depending on the relationship between the DC power source E and the discharge lamp La. It is also possible to use DC-DC conversion circuits having other configurations.

  The polarity inversion circuit 2 is a full-bridge inverter circuit in which four switching elements Q2 to Q5 are bridge-connected, and a pair of arms each formed of a series circuit of a pair of switching elements Q2 to Q5 are connected in parallel. The arm is connected between both ends of the smoothing capacitor C1. Further, a series circuit of an inductor L2 and a capacitor C2 is inserted between connection points of each pair of switching elements Q2 to Q5 constituting each arm, and a discharge lamp La is connected between both ends of the capacitor C2. However, the polarity inversion circuit 2 is not essential, and any other configuration than the configuration illustrated may be used as long as it is a lighting circuit capable of stably lighting the discharge lamp La by the output of the DC-DC conversion circuit 1. It may be used. For example, instead of applying an alternating voltage to the discharge lamp La, a non-alternating DC voltage may be applied.

  The control circuit 3 monitors the supply current from the DC power supply E and the output voltage of the DC-DC conversion circuit 1 by monitoring the voltages at both ends of the resistors R1 and R3, and controls on / off of the switching elements Q1 to Q5. A control signal for outputting is output. On / off of the switching elements Q2 to Q5 provided in the polarity inverting circuit 2 is controlled by a two-phase control signal generated by the full bridge control unit 5 according to an instruction from the control circuit 3. The full bridge control unit 5 gives a control signal to the switching elements Q2 to Q5 via drive circuits (for example, using IR2111 manufactured by IR) 6a and 6b. The voltage across the resistor R3 is a voltage proportional to the output voltage of the DC-DC conversion circuit 1 (the voltage across the smoothing capacitor C1) and reflects the voltage across the discharge lamp La (hereinafter referred to as the lamp voltage). .

  The control circuit 3 includes a microcomputer (hereinafter referred to as a “microcomputer”. For example, an M37540 manufactured by Mitsubishi) is used. The microcomputer 10 converts the voltage across the resistor R3 into an A / D converter 13 (FIG. 7). As described above, since the voltage across the resistor R3 is proportional to the power supply voltage of the polarity inverting circuit 2, the voltage applied to the discharge lamp La (that is, the lamp voltage) is reflected.

  By the way, high-intensity discharge lamps used for projectors and automobile headlamps flow a relatively large constant current (a current larger than the rated current) in a predetermined period immediately after startup in order to shorten the rise time of light output. In general, the power control is performed to increase the mercury vapor pressure by controlling the current, and to supply constant power so that the light output is kept stable in the steady lighting state after the light output increases due to the mercury vapor pressure increase. Is. Such control is performed by the microcomputer 10 by monitoring the output of the A / D converter 13. The period for performing current control and the period for performing power control are determined by the microcomputer 10 by monitoring changes in the output voltage of the DC-DC conversion circuit 1. That is, immediately after the start of the discharge lamp La, the voltage across the discharge lamp La is low, so the voltage across the resistor R3 is lower than the specified voltage (voltage defined based on the voltage during stable lighting). The current control is performed with the period as the starting period, and the power control is performed assuming that the lighting is stable when the voltage exceeds the specified voltage.

  The target value of current in current control and the target value of power in power control (hereinafter referred to as constant power mode) are set in the microcomputer 10. A voltage corresponding to the lamp voltage output from the A / D converter 13 during the operation in the constant power mode is associated with the power control data in advance by a data table. By using the data table, the A / D converter 13 is used. Is converted into power control data. A correction amount of supplied power corresponding to the difference between the power control data and the above-described power target value is given to the PWM control circuit 7. In the PWM control circuit 7, the correction amount of the output voltage of the DC-DC conversion circuit 1 is obtained by using the supply current detected as the voltage across the resistor R 1 and the correction amount of the power given from the microcomputer 10 to correct the voltage. A control signal having a pulse width corresponding to the amount is generated to control on / off of the switching element Q1. Since the voltage across the resistor R1 corresponds to the supply current from the DC power supply E, it reflects the current consumption. Note that the PWM control circuit 7 generates a triangular wave or sawtooth wave having a predetermined frequency, and uses a level corresponding to the voltage correction amount obtained by dividing the power correction amount by the input current as a threshold value. A pulse-shaped control signal for turning on / off the switching element Q1 is generated by generating a pulse that turns on a section of the waveform wave equal to or greater than the threshold value.

  By the way, the present invention is characterized in that the control circuit 3 can select a high power mode in which the output power of the DC-DC conversion circuit 1 is larger than the constant power mode during the stable lighting period of the discharge lamp La. In the high power mode, the power target value is raised. The high power mode can be selected for both the rated lighting and the dimming lighting, and the high power mode may be configured to select not only one stage but also two or more stages of power in the high power mode. For example, in the example shown in FIG. 2, it is possible to select two levels of power P1 and P2 (P1 ′, P2 ′) in the high power mode as compared to the power P (P ′) in the constant power mode. Here, the value in parentheses represents the power at the time of dimming lighting. 2 is a voltage range of the starting period, and the voltage range D2 is a working voltage range set before and after the rated voltage V0 of the discharge lamp La (used during lighting except the starting period of the discharge lamp La). Voltage range). In the illustrated example, only one level of dimming lighting is shown, but dimming lighting may be set in a plurality of levels. When the dimming stage is a plurality of stages, it is desirable to set the high power mode stage for each dimming stage.

  By the way, the control circuit 3 selects the high power mode when a situation occurs in which the temperature of the electrode or the temperature in the valve decreases and flicker occurs. As described above, the high power mode is selected when the lamp voltage of the discharge lamp La becomes equal to or higher than the threshold voltage Vt1 higher than the rated voltage V0. That is, when the lamp voltage becomes higher than the threshold voltage Vt1 higher than the rated voltage V0, it is considered that the temperature in the electrode and the bulb is lowered due to the decrease in the lamp current. At this time, the electrode and bulb are selected by selecting the high power mode. The temperature drop inside is suppressed. In the illustrated example, the high power mode can be selected from two stages, and which of the two stages is selected may be determined by other conditions (for example, ambient temperature). In the illustrated example, the same threshold voltage Vt1 is used for rated lighting and dimming, but the threshold voltage Vt1 may be different for rated lighting and dimming.

  In the example shown in FIG. 3, since the high power mode is always selected during the period when the lamp voltage of the discharge lamp La is equal to or higher than the threshold voltage Vt1, the mode returns to the constant power mode until the lamp voltage becomes lower than the threshold voltage. There is no. On the other hand, the high power mode may be selected only during a predetermined period of the period where the lamp voltage is equal to or higher than the threshold voltage Vt1. That is, the timing for returning from the high power mode to the constant power mode is controlled by time. For example, as shown in FIG. 4, the high power mode is selected for a certain period Th from the time when the lamp voltage becomes equal to or higher than the threshold voltage Vt1 (time t1 in the figure). With such an operation, since the lamp voltage of the discharge lamp La is higher than the rated voltage and the lamp current decreases and the temperature in the electrodes and bulbs decreases, the supply power is increased only for a certain period Th. While suppressing, overheating of an electrode and a valve can be prevented. Note that a function built in the microcomputer 10 is used for the predetermined period Th.

  As a condition for selecting the high power mode, as shown in FIG. 5, it may be a predetermined period Tg from the point of time when constant power is supplied after the discharge lamp La is started. Under this condition, in a predetermined period (fixed period) Tg immediately after reaching a state in which constant power is supplied after starting the discharge lamp La, that is, a period required for the electrode temperature to stabilize after the arc discharge is started. By increasing the power supply, the temperature inside the electrode or valve can be quickly raised, and the temperature of the electrode or valve can be easily stabilized.

  As described above, the technique of selecting the high power mode in the predetermined periods Th and Tg after the specific condition is satisfied temporarily increases the temperature of the electrodes and valves, but when the ambient temperature is low, After returning from the high power mode to the constant power mode, the temperature of the electrodes and valves may drop again. Therefore, as shown in FIG. 6, the constant power mode and the high power mode are alternately selected at a predetermined period (constant period) Pd from the time when the constant power is supplied after the discharge lamp La is started. It may be. Such an operation makes it easy to maintain the temperature in the electrodes and bulbs even if there are various changes such as changes in the surrounding environment and fluctuations in the power supply voltage while the discharge lamp La is lit. Generation and electrode deterioration can be suppressed.

(Basic configuration 2)
In this example, as shown in FIG. 7, a flicker detection unit 11 as flicker detection means and a timer 12 for timed operation described later are added to the basic configuration 1 shown in FIG. Further, in order to detect the lamp current of the discharge lamp La, a resistor R4 is inserted between the negative electrode of the smoothing capacitor C1 and the switching element Q3, and a current detector 8 for detecting the voltage at both ends of the resistor R4 is provided. A light output detector 9 for detecting the light output of the lamp La is provided. As the light output detector 9, for example, a light receiving element such as a photodiode disposed in the vicinity of the discharge lamp La is used. The voltage across the resistor R3 corresponding to the lamp voltage, the output of the current detector 8 corresponding to the lamp current, and the output of the light output detector 9 reflecting the light output are respectively passed through the A / D converters 13-15. Input to the microcomputer 10. Here, since the voltage across the resistor R3 is a voltage smoothed by the smoothing capacitor C1 and may be considered constant within the sampling period of the A / D converter 13, it is directly input to the A / D converter 13. The voltage across the resistor R4 fluctuates due to the switching of the switching elements Q2 to Q5 in the polarity inverting circuit 2, and the resistor R4 is a small resistor and the voltage across the resistor is low. 8 to the A / D converter 14.

  The flicker detection unit 11 detects the occurrence of flicker in the discharge lamp La, and outputs a digital value corresponding to the lamp voltage output from the A / D converter 13 and the A / D converter 14. The occurrence of flicker is detected using at least one element of a digital value corresponding to the lamp current and a digital value corresponding to the light output of the discharge lamp La output from the A / D converter 15 as a detection element.

  In this example, the control circuit 3 selects the high power mode on the condition that the flicker detection unit 11 detects the occurrence of flicker in the discharge lamp La, and the period during which flicker is detected or flicker is detected. The high power mode is selected in a predetermined period (fixed period) from the time when the operation is performed. A timer 12 is built in the microcomputer 10 in order to time out a predetermined period from the time when flicker is detected.

  The reason why the high power mode is selected during the period when flicker is detected is that the cause of flicker is considered to be due to the temperature drop in the electrode or valve, and the temperature in the electrode or valve when flicker occurs. It is possible to suppress flicker by raising. Further, the configuration in which the high power mode is selected in a predetermined period from the time when the flicker is detected, so that even if flicker occurs and the supplied power is increased and the flicker stops immediately, it operates in the high power mode for the predetermined period. As a result, the temperature inside the electrode and the bulb can be sufficiently increased. On the other hand, even if flicker occurs and flicker does not stop even if the supply power is increased, the high power mode ends in a predetermined time, so by increasing the supply power unnecessarily for a long time. Wasteful power consumption can be suppressed.

  As a technique for detecting the occurrence of flicker in the flicker detection unit 11, at least one of the above-described detection elements of lamp voltage, lamp current, and light output is used, and the amount of change of the value of the detection element within a unit time is obtained. A technique for determining that flicker has occurred when the amount of change is greater than or equal to a specified value, or using at least one of the detection elements described above, and the amount of change within a unit time of the value of the detected element is greater than or equal to a specified value. A technique is used in which a certain number of times is obtained at regular intervals, and it is determined that flicker has occurred if the obtained number is equal to or greater than a prescribed threshold value.

  That is, as shown in FIG. 8, the value of the detection element in the unit time Δt is read (S1), and the amount of change in the value of the detection element in the unit time Δt is obtained (S2). The change amount is an absolute value of the difference between the maximum value and the minimum value in the unit time Δt, and by comparing the change amount with a specified value (S3), it can be determined whether or not flicker occurs. . That is, if the amount of change is equal to or greater than the specified value, it is determined that flicker has occurred (S4). The relationship between the change in the value of the detection element and the unit time Δt is shown in FIG.

  As described above, the amount of change in the value of the detection element within the unit time Δt is obtained as an absolute value of the difference between the maximum value and the minimum value within the unit time Δt. For example, a lamp voltage is used as the detection element. As shown in FIG. 9B, if the lamp voltage changes as Vla1, Vlamin (minimum value),... Vlamax (maximum value),..., Vla2 within the unit time Δt, Vlamax−Vlamin changes. Use for quantity. Further, as a change amount, an absolute value of a difference between two adjacent measurement values may be used for the measurement value sampled every unit time Δt. For example, if the example of FIG. 9B is used, | Vla2-Vla1 | may be used as the amount of change. If the amount of change is obtained in this way, the number of samplings is small and the processing is simple, but if it is necessary to obtain the amount of change with high accuracy, it is desirable to obtain the difference between the maximum value and the minimum value. Here, the lamp voltage is exemplified as the detection element, but either the lamp current or the light output may be used, or two or more of the three may be used in combination. When two or more types of detection elements are combined, if it is determined that flicker has occurred for two or more types of detection elements, it is determined that the flicker has occurred, or if any one type of detection element has flicker. What is necessary is just to judge it as flicker when it is judged.

  By the way, when a rectangular wave voltage is applied to the discharge lamp La to light it, immediately after the polarity of the applied voltage is reversed, the value of the detection element varies due to overshoot or the like as shown in FIG. The voltage waveform is disturbed). In this period, there is a possibility that it is misunderstood to determine whether or not flicker occurs from the detection element. Therefore, it is desirable to exclude the period immediately after the polarity inversion of the lamp voltage as the period for detecting the value of the detection element in order to determine the occurrence of flicker. For example, as shown in FIG. 10, a period Ts for detecting the value of the detection element after a predetermined time from polarity inversion is provided. In the illustrated example, the lamp current is the passing current of the discharge lamp La, and the lamp voltage is the voltage across the resistor R3.

  In addition, the value of the detection element is detected in the latter half of the period from the polarity reversal to the next polarity reversal for each polarity reversal, and the detection element value detected for each polarity reversal is used (that is, the unit time Δt is polarity reversal). The occurrence of flicker (corresponding to a half cycle of the above) may be determined. Alternatively, the detection element value may be detected for each cycle of polarity inversion, and an average value obtained by averaging the detected detection element values in a plurality of periods may be used to determine whether or not flicker occurs.

  As described above, in the flicker detection unit 11, as shown in FIG. 11, the number of times that the amount of change in the value of the detection element within the unit time Δt is equal to or greater than the specified value is obtained every fixed period, and the obtained number of times is specified. If it is equal to or greater than the threshold, it may be determined that flicker occurs. That is, the flicker detection unit 11 counts the number of times, and when it is determined whether or not flicker occurs, the count value is first reset (S1). Next, the value of the detection element in the unit time Δt is read (S2), and the amount of change in the value of the detection element in the unit time Δt is obtained (S3). Further, the amount of change is compared with a specified value (S4). If the amount of change is equal to or greater than the specified value, the count value is incremented (S5), and the count value is compared with a threshold value (S6). Here, when the count value is equal to or greater than the threshold value, it is determined that flicker has occurred (S7). On the other hand, when the change amount is less than the specified value or the count value is less than the threshold value, it is determined whether or not it is within the determination period Td that is a fixed period (S8), and if within the determination period Td, the process returns to step S2. Read next value of detection element. The determination period Td is a period that is an integral multiple of the unit time Δt, and if the condition of step S6 (the count value is equal to or greater than the threshold value) is not satisfied within the determination period Td, the process returns to step S1 and the count value is reset. . Note that the unit time Δt, the specified value, and the change amount may be specified in the same manner as the processing shown in FIG.

  FIG. 12 shows an example in which the presence / absence of occurrence of flicker is determined by the processing procedure shown in FIG. In the illustrated example, the case where the amount of change in the unit time Δt is greater than or equal to the prescribed value is represented by ◯, and the case where the amount of change is less than the prescribed value is represented by ×. The flicker detection unit 11 determines that flicker has occurred when the number of circles exceeds the threshold during the determination period Td. In general, when the frequency at which the light output changes is 3 to 15 Hz, the human eye feels flickering to cause discomfort. Therefore, it is desirable to set the determination period Td to 1 second and set the threshold in the range of 3 to 15 times. . Other configurations and operations are the same as those of the basic configuration 1.

  The discharge lamp La described in each of the above examples enables illumination with little flicker and no discomfort when used for illumination, while using a light source close to a point light source when used as a light source for a projector such as a liquid crystal projector. It is possible to obtain a stable light output with less flicker. Other configurations and operations are the same as those of the basic configuration 1.

(Embodiment 1)
As described in the above examples, in the high power mode, the output power of the DC-DC conversion circuit 1 (see FIG. 16) is made larger than that in the constant power mode. However, since the purpose of increasing the power in the high power mode is to increase the temperature of the electrode and the temperature in the valve, the effective value of the power does not necessarily have to be increased, and the output from the DC-DC conversion circuit 1 is not necessary. The object can be achieved even if the power is increased during a part of the period of the rectangular wave voltage. Since the value of power in the half-cycle period of the rectangular wave voltage is represented by a peak value in a sine wave, the output of the DC-DC conversion circuit 1 is a rectangular wave voltage, but will be referred to as a peak value below. In the high power mode, if the effective value of power is made larger than that in the constant power mode, the temperature of the electrode and the temperature in the bulb can be quickly increased. However, if the effective value of power is increased, the light output changes. Therefore, in order to suppress the change in the light output, it is desirable to make the effective value of power equal to that in the constant power mode and increase the peak value in the high power mode. In short, in the high power mode, it is only necessary to increase at least one of the effective value and peak value of power. In the following, it is assumed that the power supplied to the discharge lamp La is controlled by controlling the lamp current Ila.

  When both the effective value and the peak value of the lamp current Ila are increased in the high power mode, the DC-DC conversion circuit 1 is controlled by the control circuit 3 so that the lamp current Ila becomes as in each example shown in FIG. Control the output of. In FIG. 13, the solid line shows the lamp current Ila in the high power mode, and the broken line shows the lamp current Ila in the constant power mode. That is, in the high power mode, except for the period in which the lamp current Ila is increased compared to the constant power mode, the lamp current Ila is set to be the same as that in the constant power mode, and the effective value of the lamp current Ila is constant power. Increase than mode.

  FIG. 13A shows a half-cycle period (from polarity reversal to the next reversal) for each unit period in which the polarity of the rectangular wave voltage is reversed a predetermined number of times (5 times in the illustrated example) in the high power mode. The lamp current Ila is made larger than the other periods, and as a result, the peak value of the lamp current Ila is increased by one half cycle period every five polarity inversions of the lamp voltage. . In FIG. 13A, the number written below the rectangular wave indicates the number of times of polarity inversion of the lamp voltage within the unit period in which the peak value of the lamp current Ila is increased.

  FIG. 13B is an example in which, in the high power mode, the peak value of the lamp current Ila is increased twice each time the polarity is inverted a specified number of times (5 times in the illustrated example). In FIGS. 13A and 13B, the unit period for increasing the peak value of the lamp current Ila is set to a period in which the polarity of the lamp voltage is inverted an odd number of times, so that the two electrodes of the discharge lamp La are consumed. Becomes substantially equal. On the other hand, the unit period for increasing the peak value of the lamp current Ila can be set to a period in which the polarity of the lamp voltage is inverted an even number of times (six times in the illustrated example) as shown in FIG. is there. In this case, the temperature of one of the two electrodes of the discharge lamp La can be intensively increased. That is, when the temperature distribution of the two electrodes of the discharge lamp La is biased, unevenness of the temperature distribution can be eliminated by increasing the heating amount of the electrode having the lower temperature.

  In the example shown in FIG. 13, the effective value of the lamp current Ila is increased in the high power mode than in the constant power mode. However, if the effective value is increased as described above, the light output of the discharge lamp La changes, and this Such control is not preferable when the discharge lamp La is used for a light source such as a projector. Therefore, as in each example shown in FIG. 14, in the high power mode, the peak value of the lamp current Ila is set to the constant power mode except for the period in which the peak value of the lamp current Ila is increased in each half cycle of the rectangular wave voltage. And the peak value of the lamp current Ila is made smaller and the effective value of the lamp current Ila is controlled to be equal in the constant power mode and the high power mode. 14 (a) and 14 (b) correspond to FIGS. 13 (a) and 13 (b). FIG. 14 (a) increases the lamp current Ila only once every five times, and FIG. An example in which the lamp current Ila is increased twice at a time. FIG. 14C shows an example in which the lamp current Ila is increased twice every seven times, and is controlled such that the interval between each half cycle for increasing the lamp current Ila is at least one cycle apart. That is, if the interval of each half cycle for increasing the lamp current Ila is within half a cycle, there is a possibility that a deviation occurs between the large period and the small period of the lamp current Ila within the unit period, and flicker may occur. On the other hand, flicker can be prevented by dispersing the period during which the peak value of the lamp current Ila is increased as shown in FIG.

  In the operation example shown in FIG. 14, the period corresponding to the odd number of polarity inversions is a unit period. However, as described with reference to FIG. 13C, a temperature difference occurs between the two electrodes of the discharge lamp La. It is effective to use an even number of polarity inversion periods as a unit period. That is, control as in each example shown in FIG. 15 is possible. FIG. 15A shows that the peak value of the lamp current Ila is made larger than that in the constant power mode for one half cycle within the period of six polarity reversals, and the peak value of the lamp current Ila is determined for the remaining period. It is smaller than the power mode. Further, FIG. 15B increases the peak value of the lamp current Ila twice every six times, and FIG. 15C shows the lamp current Ila only once every six times as in FIG. 15A. Although it is control which enlarges a peak value, the example from which the polarity of an electric current differs from Fig.15 (a) is shown.

  A configuration for realizing the operation example shown in FIGS. 13 to 15 is shown in FIG. The configuration shown in FIG. 16 is basically the same as the basic configuration 1 shown in FIG. 1, and two resistors R4, R4 are provided between the microcomputer 10 constituting the control circuit 3 and the PWM control circuit 7. The difference is that an integration circuit using R5, capacitor C3 and diode D2 is inserted. The integration circuit has a function of converting a pulse signal output from the microcomputer 10 with a duty corresponding to the voltage across the resistor R3 into a DC voltage Vref by the resistor R4 and the capacitor C3, and further increases the power output from the microcomputer 10. By applying the pulse signal IlaUP to the capacitor C3 through the resistor R5 and the diode D2, the DC voltage Vref applied to the PWM control circuit 7 is increased in the voltage input to the PWM control circuit 7 during the generation period of the power increase pulse signal. It has a function.

  That is, two-phase signals FB1 and FB2 having opposite phases given from the microcomputer 10 to the full bridge controller 5 (signals similar to the control signals given from the full bridge controller 5 to the drive circuits 6a and 6b) are shown in FIG. (A) At the timing shown in (b), the microcomputer 10 counts the number of times of polarity inversion with the signals FB1 and FB2, and at the timing described with reference to FIGS. A power increasing pulse signal IlaUP as shown in FIG. Since the voltage across the capacitor C3 rises during the period when the power increase pulse signal IlaUP is generated, the voltage Vref input to the PWM control circuit 7 also rises during this period as shown in FIG. The voltage Vref input to the PWM control circuit 7 is a target value, and the DC-DC conversion circuit 1 is controlled to increase the lamp current detected by the resistor R1 as the voltage Vref is higher. The increase in lamp current due to the power increase pulse signal IlaUP is adjusted by the size of the resistor R5.

  The operation of this embodiment is summarized as shown in FIG. The conditions for shifting to the high power mode are that the lamp voltage is equal to or higher than the threshold voltage, that the lamp is switched to dimming lighting, flicker occurs, and the like, as shown in FIG. A mode in which the effective value of the lamp current Ila is increased (hereinafter referred to as “power increase mode”) or a mode in which the effective value of power as shown in FIGS. (Referred to as “the same value mode”) (S1). This selection can be set according to the condition for shifting to the high power mode. For example, the power increase mode is selected when shifting to the high power mode due to the occurrence of flicker, and the same effective value mode is selected when other conditions are met.

  In the power increase mode, the lamp current Ila is set to the constant power mode except for the period in which the peak value of the lamp current Ila is increased (S2). Further, in the same effective value mode, the lamp current Ila is set so that the effective value of the lamp current Ila as a whole is the same as the lamp current Ila in the constant power mode except for the period in which the peak value of the lamp current Ila is increased. (S3). In any case, the microcomputer 10 counts the number of polarity inversions (S4), increases the lamp current Ila during the prescribed number of half-cycle periods (S5), and increases the lamp current Ila during other periods. Release (S6).

  Note that if the half cycle period for increasing the lamp current Ila is short, the effect of increasing the lamp current Ila cannot be obtained, and if it is long, the electrode is adversely affected. Therefore, it is desirable to set it to about 0.5 to 50 ms. If the increase rate of the lamp current Ila is small, no effect is obtained, and if it is large, flickering of the light output is visually recognized. Therefore, the lamp current Ila in the half cycle of the period when the lamp current Ila is not increased is used as a reference value. It is desirable to set it to about 5 to 60% higher than the reference value. However, the effect of increasing the lamp current Ila in the high power mode is that the half-cycle period and the rate of increase of the lamp current Ila are related to each other, so an optimum value is determined according to the characteristics of the discharge lamp La. It is necessary to.

  Incidentally, when a discharge lamp La having a rated power of 150 W is used and the frequency of the rectangular wave voltage is 170 Hz, each power of 135 W, 140 W, and 145 W is supplied to the discharge lamp La, and the peak value of the lamp current Ila. And the peak value of the lamp current Ila during another half period within the unit period in which the polarity of the lamp voltage is inverted five times as in the high power mode operation example shown in FIG. When the discharge lamp La is turned on for one hour when the increase rate is set to 30% and the increase rate is set to 30%, the peak value of the lamp current Ila is kept constant over a relatively long period. An arc jump (a phenomenon in which the end position of the arc is not stable and moves from place to place, and the light output changes) occurs, whereas the lamp The arc jump did not occur in the case of increasing the flow Ila in the unit period by the time of the half cycle of the polarity inversion. Other configurations and operations are the same as those of the basic configuration 1.

(Embodiment 2)
In each of the above-described examples, a configuration in which the voltage applied to the discharge lamp La is alternated at a constant period is adopted. However, in the present embodiment, the lamp current Ila is increased as shown in FIGS. 19 (a) and 19 (b). The periods Tn and Tw are different from the other periods Tu. That is, in FIG. 19A, the period Tn for increasing the lamp current Ila is shorter than the other period Tu (Tn <Tu), and in FIG. 19B, the period Tw for increasing the lamp current Ila is set to the other period Tu. This is an example in which it is longer (Tw> Tu). As described in the first embodiment, the increase rate of the lamp current Ila and the half-cycle time are related to the apparatus, so that the periods Tn and Tw for increasing the lamp current Ila are increased or decreased with respect to the other periods Tu. The desired lamp current Ila can be applied to the discharge lamp La.

  For example, if the discharge lamp La has an adverse effect on the electrode if the period Tn for increasing the lamp current Ila is made equal to the other period Tu, the influence on the electrode can be reduced by shortening the period Tn. If the lamp current Ila of the discharge lamp La has an upper limit value and the period Tw is equal to the other period Tu, the required energy cannot be supplied to the discharge lamp La. It becomes possible. Other configurations and operations are the same as those of the basic configuration 1.

(Embodiment 3)
In each example described above, basically, as shown in FIG. 20, the peak value of the lamp current Ila is kept constant during the constant power mode period Pb1, and the peak of the lamp current Ila is maintained during the high power mode period Pb2. The value is changed.

  In the present embodiment, an example will be described in which the peak value of the lamp current Ila is changed not only in the high power mode but also in the constant power mode. In this case, in the constant power mode and the high power mode, at least one element of the frequency of the rectangular wave voltage, the peak value of the lamp current Ila, and the frequency of the period in which the lamp current Ila is increased is changed.

  Note that the transition conditions between the high power mode and the constant power mode are the same as those in the above-described examples. To summarize, the transition conditions from the constant power mode to the high power mode are such that the lamp voltage is within the specified range. If it is (above the threshold voltage and below the upper limit voltage possible for circuit operation), if the power supplied to the discharge lamp La is reduced, or if a predetermined time has elapsed after the discharge lamp La is turned on, the cumulative lighting of the discharge lamp La When the time reaches a predetermined time, there are five conditions when flicker or arc jump is detected. Although the cumulative lighting time is not particularly described in each of the above-described examples, the cumulative lighting time is measured by providing a timer for accumulating the lighting time of the discharge lamp La (the period from power-on to power-off). The flicker is detected by the flicker detection unit 11 described in the basic configuration 2. As for the arc jump, a photoelectric sensor is arranged in the vicinity of the discharge lamp La, and it is determined that the arc jump occurs when the brightness difference within a specified short time exceeds the threshold for a predetermined time. . Therefore, the flicker detection unit 11 is used for arc jump detection.

  On the other hand, the transition condition from the high power mode to the constant power mode (that is, the return condition) is that the power supplied to the discharge lamp La is increased when the lamp voltage is out of the specified range (below the above threshold voltage and 0 V or more). In this case, there are four conditions when a predetermined time has elapsed after shifting from the constant power mode to the high power mode, and when flicker and arc jump are no longer detected. Since the cumulative lighting time only increases, there is no condition for returning to the constant power mode corresponding to the cumulative lighting time. In addition, when a transition is made from the constant power mode to the high power mode due to the detection of flicker or arc jump, it is not a condition that flicker or arc jump is not detected, and that a predetermined time elapses after transition to the high power mode. As a condition, the high power mode may be returned to the constant power mode. If the return condition is defined by time in this way, the high power mode does not end indefinitely when flicker or arc jump occurs due to deterioration of the discharge lamp La or the like, and thus excessive stress is applied to the circuit elements. Can be prevented. The transition condition between the constant power mode and the high power mode can be set as appropriate in addition to the above example.

  Of the above-described conditions, Table 1 summarizes the relationship between the high power mode and the constant power mode, the lighting state of the discharge lamp La (rated lighting and dimming lighting), and the lamp voltage. Table 1 only shows the conditions for performing the operation in the high power mode and the constant power mode. Of course, the supplied power is less when the dimming is turned on than when the rated light is turned on. That is, in the operation shown in FIG. 20, the lamp current Ila to the discharge lamp La is increased in the high power mode. Therefore, this operation is based on the time, flicker or arc jump detection condition for the transition to the high power mode. It corresponds to the case of things. As described in the first embodiment, the effective value is kept constant when the lamp voltage increases to shift to the high power mode, and the effective value is reduced as compared with the constant power mode when the lamp shifts to the high power mode due to dimming lighting. The “rated range” in Table 1 means a range set before and after the rated voltage in consideration of variations in characteristics of the discharge lamp La. Therefore, the lower limit and the upper limit of the rating mean the lower limit and the upper limit of the rated range.

  First, a case where only the frequency of the rectangular wave voltage is changed will be described. That is, in the example shown in FIG. 21, in any of the two types of periods Pb1 and Pb2, a period in which the polarity of the rectangular wave voltage applied to the discharge lamp La is reversed a specified number of times is defined as a unit period, and a part of the unit period Only in the period, the operation of increasing the peak value of the lamp current Ila is performed compared to the other periods, and the frequency is higher in the period Pb2 than in the period Pb1. In the illustrated example, the lamp current Ila is increased only for a half cycle period with respect to five polarity inversions.

  By this operation, the number of times of increasing the peak value of the lamp current Ila per unit time increases, so that the electrode of the discharge lamp La becomes difficult to cool, and a stable light output with less flicker can be obtained.

  The frequency is not limited to two stages, and three or more stages can be used. Assuming that three stages of f1, f2, and f3 (f1 <f2 <f3) are used as frequencies, frequency f2 is selected in (rated lighting, rated upper limit) (dimming lighting, rated range) in Table 1 Then, the frequency f3 is selected for (dimming lighting, above the rated upper limit), and the frequency f1 is selected for other conditions. If it is necessary to keep the effective value of the lamp current Ila constant or increase the effective value while changing the frequency, the amplitude of the rectangular wave voltage may be changed.

  In the periods Pb1 and Pb2, the frequency of the period in which the lamp current Ila is increased may be changed. To change the frequency, there are a case where the number of times of switching the polarity of the rectangular wave voltage in the unit period is changed and a case where the number of times the lamp current Ila is increased within the unit period. The example shown in FIG. 22 is obtained by changing the number of times the polarity is switched as a unit period. In the period Pb1, the lamp current Ila is increased by one half cycle period while the polarity is inverted five times. In Pb2, the lamp current Ila is increased only for the period of one half cycle while the polarity is inverted three times (period of three half cycles). Similarly to the case of switching the frequency, it is also possible to switch to three or more stages. For example, in the condition that the power supplied to the discharge lamp La is the smallest in Table 1, that is, the condition (dimming lighting, above the rated upper limit) The period in which the polarity is inverted five times may be defined as a unit period, and two half cycles of polarity inversion in the unit period may increase the lamp current Ila in two periods more than the other periods in the unit period. . However, since the lighting is dimming, it is necessary to adjust the amplitude of the rectangular wave voltage so that the effective value of the lamp current Ila is lower than the rated lighting.

  In the constant power mode and the high power mode, the frequency of the period during which the lamp current Ila is increased may be changed. To change the frequency, there are a case where the number of times of switching the polarity of the rectangular wave voltage in the unit period is changed and a case where the number of times the lamp current Ila is increased within the unit period. The example shown in FIG. 22 is obtained by changing the number of times the polarity is switched as a unit period. In the period Pb1 in the constant power mode, the lamp current Ila is supplied only for one half cycle period while the polarity is inverted five times. In the high power mode period Pb2, the lamp current Ila is increased only for one half cycle period while the polarity is inverted three times (three half cycle periods). Similarly to the case of switching the frequency, it is also possible to switch to three or more stages. For example, in the condition that the power supplied to the discharge lamp La is the smallest in Table 1, that is, the condition (dimming lighting, above the rated upper limit) The period in which the polarity is inverted five times may be defined as a unit period, and two half cycles of polarity inversion in the unit period may increase the lamp current Ila in two periods more than the other periods in the unit period. . However, since the lighting is dimming, it is necessary to adjust the amplitude of the rectangular wave voltage so that the effective value of the lamp current Ila is lower than the rated lighting.

  When the peak value of the lamp current Ila is changed in the periods Pb1 and Pb2, the control may be performed as shown in FIG. The illustrated example shows a case where the effective value of the lamp current Ila is made equal in the periods Pb1 and Pb2. In the period Pb2, the peak value is made larger than the period Pb1 in the period in which the peak value of the lamp current Ila is increased. During this period, the peak value is made smaller than that of the period Pb1. Also in this case, like the other elements described above, three or more stages can be set. For example, in the period in which the peak value is increased, the peak value is further increased than the period Pb2 in FIG. By further reducing the peak value, the peak value of the lamp current Ila can be increased while keeping the effective value constant.

  In the example described above, an example in which any one of the frequency, the frequency, and the peak value is changed in the periods Pb1 and Pb2 is shown, but two or more elements may be changed in combination. For example, as in the example shown in FIG. 24, the frequency and the peak value can be changed. By combining multiple elements in this way, it is possible to set the target output so as not to deviate from the control range by combining multiple elements, even if the change of a single element alone deviates from the control range. become. Moreover, it becomes possible to expand the range of the target output, for example, it becomes possible to widen the light control range. Other configurations and operations are the same as those of the basic configuration 1.

(Embodiment 4)
The present embodiment is an example in which the lamp La that is lit by the above-described discharge lamp lighting device is used as a light source of a projector. Is illustrated. The lamp La and the discharge lamp lighting device are housed in a housing together with a DMD element and a fan. A projection lens protrudes from a part of the housing. This type of projector has a disc-shaped color filter 16 as shown in FIG. 25 in front of the light source, and is configured to reflect the light transmitted through the color filter 16 with a DMD element. The color filter 16 is divided into red (R), green (G), blue (B), and colorless (W) regions, and rotates in a direction of an arrow X in FIG. Therefore, as shown in FIG. 26A, the transmitted color of the color filter 16 changes as red (R), green (G), blue (B), and white (W) with time. .

  The timing of switching the polarity of the voltage applied to the discharge lamp La used as the light source is made to coincide with the boundary of each color region in the color filter 16, as shown in FIG. By setting the timing for switching the polarity of the voltage applied to the discharge lamp La as described above, the light passing through each color region of the color filter 16 does not become light in a state where the light output is reduced at the time of switching the polarity. The light emitted from the discharge lamp La can be used efficiently. However, the red region of the color filter 16 has a larger area than the other regions, and the period during which light from the discharge lamp La is transmitted through the red region is longer than the period during which light is transmitted through the other region. Since the length is longer, the polarity is switched during a period in which light is transmitted through the red region. Further, as shown in FIGS. 26B and 26C, in the illustrated example, the lamp current Ila is increased more than the other period in the period in which the light is transmitted to the red area, but the light is transmitted to the other area. The lamp current Ila may be increased more than other periods in the period to be generated, and the lamp current Ila may be increased more than other periods in the period corresponding to two or more regions. FIG. 26B shows a case where the effective value of the lamp current Ila is larger than that in the constant power mode (broken line) in the high power mode (solid line), and FIG. 26C shows the lamp current Ila in the high power mode (solid line). The effective value of is equal to the constant power mode (broken line). Moreover, as the color filter 16, you may use what does not contain a colorless (W) area | region. Other configurations and operations are the same as those of the basic configuration 1. The discharge lamp lighting device of each example is not limited to the configuration of the present embodiment, and can be used for various projectors.

1 is a circuit diagram of Embodiment 1. FIG. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. FIG. 6 is a circuit diagram of a second embodiment. It is operation | movement explanatory drawing which shows the operation example of the flicker detection part in the same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing same as the above. It is operation | movement explanatory drawing which shows the other operation example of the flicker detection part in the same as the above. It is operation | movement explanatory drawing same as the above. FIG. 10 is an operation explanatory diagram of the third embodiment. It is operation | movement explanatory drawing which shows other operation | movement same as the above. It is operation | movement explanatory drawing which shows other operation | movement same as the above. It is a circuit diagram same as the above. FIG. 17 is an operation explanatory diagram illustrating signals of respective units of the circuit illustrated in FIG. 16. It is operation | movement explanatory drawing same as the above. FIG. 10 is an operation explanatory diagram of the fourth embodiment. It is operation | movement explanatory drawing same as the above. FIG. 10 is an operation explanatory diagram of the fifth embodiment. It is operation | movement explanatory drawing which shows other operation | movement same as the above. It is operation | movement explanatory drawing which shows other operation | movement same as the above. It is operation | movement explanatory drawing which shows another operation | movement same as the above. FIG. 10 is a front view illustrating a configuration example of a color filter used in Embodiment 6. It is operation | movement explanatory drawing same as the above.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 DC-DC conversion circuit 2 Inverter circuit 3 Control circuit 16 Color filter La Discharge lamp Q1 Switching element Q2-Q5 Switching element

Claims (8)

  Power in a power converter circuit that makes the power supplied to the discharge lamp, which is a high-intensity discharge lamp, variable by controlling on / off of the switching element and power in a constant power mode in which constant power is supplied to the discharge lamp when the discharge lamp is stably lit A control circuit that controls on / off of the switching element of the conversion circuit, the power conversion circuit applies a rectangular wave voltage having an alternating polarity to the discharge lamp, and the control circuit defines the polarity of the rectangular wave voltage applied to the discharge lamp The discharge lamp has a high power mode in which the lamp current supplied from the power conversion circuit is increased more than in other periods in the unit period, and the lamp current supplied from the power conversion circuit in at least one half cycle period of the rectangular wave voltage within the unit period. It can be selected during the discharge lamp lighting period after shifting to stable lighting, and in the high power mode, the effective value of the power supplied to the discharge lamp is constant Discharge lamp apparatus comprising: a power increase mode for increasing than mode.   2. The discharge lamp lighting device according to claim 1, wherein the control circuit makes the time of a half cycle in which the lamp current is increased more than other periods differ from the time of another half cycle.   3. The discharge lamp lighting device according to claim 1, wherein the control circuit changes the frequency of the rectangular wave voltage when a specific transition condition is satisfied in the high power mode.   3. The discharge lamp lighting device according to claim 1, wherein the control circuit changes a frequency of increasing a lamp current when a specific transition condition is satisfied in the high power mode. 4.   3. The discharge lamp lighting device according to claim 1, wherein the control circuit changes a peak value of a lamp current when a specific transition condition is satisfied in the high power mode. 4.   The control circuit changes two or more elements of the frequency of the rectangular wave voltage, the frequency of increasing the lamp current, and the peak value of the lamp current when a specific transition condition is satisfied in the high power mode. The discharge lamp lighting device according to claim 1 or 2.   A discharge lamp lighting device for use in a projector including the discharge lamp as a light source and a color filter in which a transmission color of light from the light source changes with time in a predetermined cycle, wherein the control circuit is a rectangular wave voltage applied to the discharge lamp. 7. The discharge lamp lighting device according to claim 1, wherein the timing of reversing the polarity of the lamp is synchronized with the timing of changing the transmitted color of the color filter.   A projector comprising the discharge lamp lighting device according to any one of claims 1 to 7.

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